JP2720428B2 - Method for manufacturing semiconductor device - Google Patents

Abstract

PURPOSE:To prevent a coated wire from being electrified at the time of a wire bonding and to prevent each mechanism of a device, which is made contact with the wire, from being electrified by a method wherein an application of ultrasonic vibrations is intermittingly performed to a bonding tool between the time ranging from a time when the metal wire at one end of the wire is exposed and is bonded to an electrode on one side to a time when the other end of the wire is bonded to the other electrode. CONSTITUTION:A coated wire 5 is made a conductive connection with a first bonding side, that is, the side of the connection of an external terminal 2C of a semiconductor chip 2 with one end of the wire 5 by a ball bonding due to the formation of a metal ball 5A1, while a second bonding side, that is, the side of the connection of an inner lead 3B of a lead 3 with the other end of the wire 5 is made a conductive connection with the wire 5 by a thermocompression bonding and ultrasonic vibrations as a bonding part 5A2 without removing previously a coated film 5B. When the wire 5 passes through a bonding tool, the outer periphery part of the wire 5 is brought into contact with the surface of a conductive substance 16C, whereby static electricity being electrified in the film 5B of the wire 5 is removed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention is effective when applied to the assembly of a semiconductor device having a highly integrated and highly functional type semiconductor chip, particularly to a wire bonding step for connecting electrodes. About technology.

[Conventional technology]

Examples of this type of technology are described in, for example, the Industrial Research Council, published on November 18, 1987, "Electronic Materials Separate Volume, Ultra LSI Manufacturing and Testing Equipment Guidebook", P123-P129
There is.

In the above-mentioned documents, technical trends relating to wire bonding in recent years and in the future, including classification of bonding methods, are described.

That is, in a semiconductor device assembling process, a conductive metal wire (wire) is provided as a technique for electrically connecting external terminals (electrode pads) of a semiconductor chip (pellet) to inner leads of a lead frame. That is, a so-called wire bonding technique is generally used.

As described in the above-mentioned literature, the space between external terminals on a semiconductor chip is promoted by promoting high integration and a multi-functionality in a microcomputer / logic product in response to a demand for an increase in storage capacity of a memory element. , And the pitch interval between the tips of the inner leads also tends to be narrowed.
Correspondingly, the wire pitch to be bonded tends to be further narrowed. When wire bonding is performed in such a situation, a bonding failure such as a short between wires (wire short), a short between a wire and a semiconductor chip or a tab (chip short, tab short) or the like has been likely to occur.

Also, with the thinning of the wires corresponding to the above,
In the bonded wire, the strength to maintain the loop shape by itself is not obtained, causing the wire to sag, etc.
This was a factor causing each of the above short circuits.

From such a viewpoint, gold (Au), aluminum (Al)
Alternatively, a so-called covered wire in which an insulating resin is applied around a conductive metal wire made of copper (Cu) or the like has been proposed.

The wire bonding method using the above-mentioned covered wire is briefly described as follows.

That is, first, the coated wire drawn out from the tip of the bonding tool is melted and removed by the high-pressure discharge action near the tip, and then the tip of the exposed metal wire is melted into a spherical shape. The first bonding is performed by pressing the spherical portion against the external terminals of the semiconductor chip while applying ultrasonic vibration.

Subsequently, while the covering wire is drawn out from the tip of the bonding tool, the other end side is landed on a predetermined portion of the inner lead so that the covering wire draws a loop shape, and ultrasonic vibration is again applied to the bonding tool. By applying the ultrasonic energy, the coating film in the portion in contact with the surface of the inner lead is destroyed / removed to expose and bond the metal wire at the same time.

[Problems to be solved by the invention]

The wire bonding technology using the coated wire is
The present inventors have clarified that the following problems to be solved remain, making it difficult to realize.

First, in the wire bonding technology using a coated wire, static electricity is generated in a portion of the coating film around the wire from the wire spool to the bonding tool,
Due to this, the covered wire is attracted to each mechanism of the wire bonding apparatus such as an airbag tensioner, a sprocket, a clamper, etc., and an extra resistance force is applied to the bonding tool during the downward movement of the bonding tool. As a result, when the wire is pulled out from the tip of the bonding tool and stretched in a loop shape, the wire breakage or an abnormal loop shape is caused. In addition, since the wire is inserted into the bonding tool while being deformed into a curl shape by the suction, there is a high possibility that the loop shape of the stretched wire may be abnormal and the wire bonding state may be defective. . Further, there is a risk that the semiconductor chip may be electrostatically damaged due to the contact of the charged wire with the pad of the semiconductor chip.

Second, due to the charging of the coated wire, a small piece of the coating film or foreign matter such as dust is adsorbed around the wire, and in this state, the wire is inserted into the bonding tool, thereby causing clogging of the bonding tool. It was clarified that the wire was poorly led or the wire was broken.

Third, even when the wire is uncharged,
It has been found that the same phenomenon as the first problem occurs when the clamper surface for clamping the wire is charged. That is, since the wire is attracted to the charged clamper surface, an extra resistance force is applied to the bonding tool when the bonding tool is lowered, and the wire is drawn out from the tip of the bonding tool. This was a cause of wire breakage or loop abnormality when the cable was stretched.
In addition, since the wire is inserted into the bonding tool while being deformed into a curl shape by the suction, there is a high possibility that the loop shape of the stretched wire may be abnormal and the wire bonding state may be defective. It is.

Because of the above-mentioned problems, it is practically difficult to connect with a coated wire, and this has caused a difficulty in realizing a highly integrated semiconductor device or a highly functional semiconductor device.

Note that the first and second problems are specific to the coated wire, but the third problem is not limited to the coated wire, and the same applies to the case where a normal bare metal wire (wire) is used. It has been confirmed by the present inventors that this is a problem that arises.

However, in the technology using the coated wire,
The present inventors have clarified that the following problems to be solved remain.

That is, when using the above-mentioned covered wire, how to remove the covering film is important in determining the quality of bonding. That is, according to the above-described conventional technology, the removal of the coating film at the time of the second bonding is performed almost simultaneously with the bonding with the internal metal wire by applying the ultrasonic vibration to the bonding tool. In many cases, the destruction and removal of the coating film is incomplete, and the remaining coating film pieces reduce the bonding strength between the metal wire and the inner lead surface, increasing the contact resistance. There is a possibility that a product defect such as wire breakage may occur.

Further, in the above-described conventional technology, it is necessary to maintain the application of ultrasonic vibration to the bonding tool for a long time on the inner lead surface in order to more completely remove the coating film. The result was a decline.

Furthermore, according to the research of the present inventors, it has been clarified that ultrasonic energy mainly intended for bonding does not necessarily contribute to improvement in the efficiency of removing the coating film.

The present invention has been made in view of the above problems,
The first object is to prevent charging of the coated wire during wire bonding using the coated wire, prevent charging of each mechanism in contact with the second wire, and assemble a highly reliable semiconductor device. It is to realize.

Third, the object is to improve the bonding reliability of the coated wire.

Fourth, to improve wire bonding efficiency.

Fifth, the object is to realize a highly integrated and highly functional semiconductor device by establishing a wire bonding technique using a covered wire.

A further object of the present invention is to provide a technique capable of improving the bonding reliability of the second bonding in wire bonding using a covered wire.

A further object of the present invention is to provide a highly reliable resin-sealed IC.

It is a further object of the present invention to provide a wire bonding technique using a covered wire without pinholes or scratches due to undesired discharge.

Another object of the present invention is to improve the accuracy of wire bonding using a lead frame having a very large number of leads.

Another object of the present invention is to improve the efficiency of applying ultrasonic waves during bonding.

It is a further object of the present invention to facilitate control of the wire loop shape.

[Means for solving the problem]

The outline of a representative invention among the inventions disclosed in the present application will be briefly described as follows.

In other words, the method of manufacturing a semiconductor device according to the present invention provides a method of manufacturing a semiconductor device, comprising: Connecting the corresponding one end to the electrode of the semiconductor chip and connecting the other portion of the metal wire selectively exposed at the other portion of the covering wire, that is, the portion corresponding to the second bonding portion to the lead. The ultrasonic vibration is continuously applied to the bonding tool between the first bonding step and the second bonding step. In each bonding process,
The energy of the ultrasonic vibration by the high energy is applied to the bonding tool, and the ultrasonic vibration by the low energy lower than the energy of the ultrasonic vibration by the high energy is continuously applied to the bonding tool other than at the time of bonding.

Then, by applying ultrasonic vibration at an intermediate energy between the low energy and the high energy to the coating film at the portion corresponding to the second bonding, the coating film at the portion is removed.

Further, a contact surface having a rough surface is formed on a bonding stage on which the lead frame is arranged, and the lead frame is fixed to the bonding stage by a pressing member. After connecting the first portion on the semiconductor chip with the coated wire having the insulator attached to the periphery of the metal wire and then connecting the second portion on the inner lead to the lead frame, the inner lead has a rough surface. It is held at the contact surface. The rough contact surface is formed by applying diamond grains to the bonding stage.

[Action]

In the present invention, the ultrasonic vibration with low energy is continuously applied to the bonding tool even during the period from the end of the first bonding to the start of the second bonding. The removal can be performed by vibration, and clogging of the bonding tool can be effectively prevented. Further, by continuously applying the ultrasonic vibration to the bonding tool, the deflection of the wire in the through hole of the bonding tool can be prevented, and the occurrence of the curling state of the wire in the through hole can be prevented.

Further, since the inner leads of the lead frame are fixed between the rough contact surface of the bonding stage and the pressing member, resonance of the inner leads when ultrasonic vibration is applied can be prevented. Further, since the surface of the inner lead is fixed so as to maintain a state parallel to the surface of the bonding stage, bonding failure due to the inclination of the inner lead and the like is also prevented.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below as appropriate, but each embodiment is not independent, and each corresponds to a part thereof or a modification of part thereof.

Therefore, in each of the following embodiments, each step or component is replaced with another embodiment.

For example, the bonding of leads by the diamond electrodeposition pressing member of Embodiment 5 can be applied to all other embodiments. Each table is attached at the end of the detailed description.

(1) Embodiment 1 FIGS. 1 (a) and 1 (b) show I of Embodiment 1 of the present invention.
Cross-sectional view showing a wire bonding procedure according to
FIG. 3 is a schematic configuration diagram of a wire bonding apparatus as an assembling apparatus used in the present embodiment, FIG. 3 is a half sectional view of a resin-sealed semiconductor device obtained by the present embodiment, and FIG. FIG. 5 is a partial cross-sectional view showing a specific structure of the main part, FIG. 6 is a plan view of the main part viewed from the direction of arrow VI in FIG. 5, and FIG. V
8 is a cross-sectional view taken along a cutting line, FIG. 8 is a copy configuration diagram showing the principle of forming a metal ball, FIG. 9 is an exploded perspective view of a main part of a wire spool of the wire bonding apparatus, and FIG. Main part enlarged perspective view, FIG. 11 is a schematic plan view of a local heating unit for wire bonding, FIG. 12 is a plan view showing an example of wire bonding, and FIG. 13 is a partial cross section showing a chip touch state of a coated wire. FIG. 14, FIG. 14 is an enlarged partial cross-sectional view showing a chip short state, FIG. 15 is a partial cross-sectional view showing a tab touch state of the coated wire, FIG. 16 is an enlarged partial cross-sectional view showing a tab short state, FIG. FIG. 18 is a graph showing the short-circuit rate between the semiconductor chip and the coated wire with respect to the temperature cycle according to the present invention; FIG. 18 is a graph showing the short-circuit rate between the tab and the coated wire with respect to the temperature cycle according to the present invention; Is a model diagram showing the experimental conditions used for evaluating the coating film of the coated wire used in the present embodiment. FIGS. 20 and 21 show the results of a comparative experiment of the wear strength of the coating film in the first embodiment. FIG. 22 is an explanatory diagram showing the results, FIG. 22 is an explanatory diagram showing the experimental results on the relationship between the temperature change and the deterioration rate of the coated wire in the description of the present embodiment, and FIG. FIG. 24 is an explanatory view showing the experimental results on the relationship between the degradation rate, that is, the degradation rate (vertical axis on the left side) and the peel strength of the second bonding of the coated wire (vertical axis on the right side). FIG. 25 is an explanatory diagram showing experimental results on temperature cycle amplitude and temperature cycle life, and FIG. 25 is an explanatory diagram showing the influence on the deterioration rate (deterioration rate) depending on whether or not a coloring agent is added to the coating film of the coating wire. FIGS. 26 to 31 show variations in the present embodiment. It is a fragmentary sectional view for explaining the wire bonding state showing a form example.

The resin-sealed semiconductor device 1 assembled through this embodiment is as shown in FIG. 3, and the semiconductor chip 2 is configured as a semiconductor integrated circuit element such as a memory, a gate array, a microprocessor and a MOS logic (logic). Have been.

This semiconductor chip 2 includes a substrate 2A made of, for example, silicon (Si) and a passivation film 2B on the top thereof.
And an external terminal 2C (bonding pad) exposed from the opening of the passivation film 2B. The semiconductor chip 2 is joined to the tab 3A of the lead 3 by a joining material 4 such as a silver (Ag) paste.

On the other hand, the external terminals 2C of the semiconductor chip 2 are electrically connected to the inner leads 3B of the leads 3 by conductive wires. In this embodiment, the covering wires 5 are used as the conductive wires. This coated wire 5 is a metal wire 5A
And a structure in which an insulating coating film 5B is applied to the surface of the substrate.

As a material of the metal wire 5A of the covered wire 5, for example, gold (Au), copper (Cu), or aluminum (Al) can be used.

The coating film 5B of the coating wire 5 is formed by reacting a polyol component with an isocyanate, and is made of a heat-resistant polyurethane having a molecular skeleton containing a structural unit derived from terephthalic acid.

With respect to such a constituent material of the coating film 5B, a result of an experiment performed by the present inventors on a resin-sealed semiconductor device after sealing will be described as Example 1. The parts in the examples are parts by weight.

Experimental Example 1 First, raw materials as shown in Table 1 below were blended in a ratio as shown in the table, and this was put into a 500 cc flask.
A thermometer and a steam condenser were attached and reacted to obtain three types of terephthalic acid-based polyols P-1, P-2 and P-3. Table 1 also shows the ratio of terephthalic acid and ethylene glycol and the reaction time at this time. The end point of the above synthesis reaction was determined based on theoretical reaction water and an acid value of 5 or less. In this case, a reduced pressure reaction was performed as needed.

Using the three types of terephthalic acid-based polyols P-1, P-2, P-3 obtained as described above and commercially available polyols, these polyol components and isocyanate components are shown in Table 2 below. A coating composition was prepared by blending at such a ratio. Then, the coating composition thus obtained is diluted to a concentration of 10% using a solvent, and applied to the outer peripheral surface of the wire body at least twice, and then heated at 175 ° C. for 21 minutes,
After-curing at 2 ° C. for 2 hours to form an insulating film made of heat-resistant polyurethane, and the wire was formed. Composition wiring in this case;
The coating properties are shown in Table 2 below.

Next, using the heat-resistant polyurethane-coated wire obtained as described above, the wire-bonded semiconductor chip 2 is molded with a resin material 6, and as shown in FIG. 13 (chip touch state) and FIG. 15 (tab touch state). A semiconductor device corresponding to the touch state shown was manufactured, a temperature cycle test of MIL-883B was performed, and a short-circuit rate comparison with a semiconductor device using a commercially available polyurethane-coated wire was performed. The improvement of the wire was evaluated.

The results of this comparative experiment were as shown in FIG. 17 and FIG. That is, FIG. 17 shows the short-circuit rate between the semiconductor chip and the coated wire in the chip touch state as shown in FIG. 13, and as apparent from FIG. 17, the heat-resistant polyurethane-coated wire of this example was used. In semiconductor devices,
As compared with a semiconductor device using a commercially available polyurethane-coated wire, a remarkable short-circuit rate, that is, an effect of preventing chip short-circuit was confirmed.

FIG. 18 shows the short-circuit rate between the tab and the coated wire in the tab chip state as shown in FIG. 15, but also in this case, in the semiconductor device using the heat-resistant polyurethane-coated wire of the present embodiment, it is remarkable. It was confirmed that a short-circuit rate, that is, an effect of preventing tab short-circuiting was obtained.

Next, the present inventors conducted a comparative experiment of the above-mentioned heat-resistant polyurethane-coated wire and a commercially available polyurethane-coated wire in a wire state before resin sealing under the test conditions described below to determine the wear strength and the deterioration rate of the coating film. evaluated. The results of these experiments and the results of various other experiments will be described below with reference to FIGS. 19 to 25 as Examples 2 to 5.

Experimental Example 2 Experimental conditions were represented by a model diagram shown in FIG. That is, a constant load (1 g) is hung on the lower end of the insulated wire 5 whose outer surface is coated with an insulating coating film (heat-resistant polyurethane of this embodiment or commercially available polyurethane) 5B to be in a vertically suspended state. , Lead frame tab 3A
At its edge at a contact angle α = 45 degrees with respect to the coated wire 5, and applies a pressing force to the coated wire 5 with a load W1 (0.65 g) in the horizontal direction from the opposite side to the tab edge contact portion,
Then, the tab 3A was vibrated up and down by 20 μm to evaluate the wear of the coating film 5B and the like.

Here, the amplitude (vibration) frequency Nf until the coating film 5B wears and breaks is defined as a wear strength and evaluated.

In addition, the heat resistance of the coating film 5B is high temperature storage (150-200 ° C,
(0 to 1000 hours).

As a result, it has been found that, in the case of polyurethane, thermal degradation can be greatly suppressed by imidizing the polyurethane, and the temperature cycle life T∞ can be significantly improved.

 Hereinafter, these experimental results will be specifically described.

First, FIGS. 20 and 21 show the thermal deterioration of the wear strength of the coating film 5B at 150 ° C. and 175 ° C., respectively (reduction of the number of coating film breakage after 100 hours). As is apparent from these figures, in the case of the coating film using the heat-resistant polyurethane of the present invention, the wear strength Nf even after the high-temperature leaving time has elapsed.
Was found to be small, and the deterioration of the coating film was very small. In particular, the fact that the rate of deterioration in reducing the number of times the coating film was destroyed after 100 hours at 150 ° C. to 175 ° C. was within 20% proved to be a very advantageous characteristic for the coated wire.

Experimental Example 3 Next, FIG. 22 shows the experimental results of the relationship between the temperature (horizontal axis) and the deterioration rate, that is, the deterioration rate [ΔNf / 100Hrs] (= NO−N100 / 100Hrs) (vertical axis). Also in this figure,
It is understood that the degradation rate of the heat-resistant polyurethane-coated wire of the present invention is much smaller than that of the commercially available polyurethane.

Experimental Example 4 Next, FIG. 23 shows the imidization rate (horizontal axis) of the coating film, the degradation rate, that is, the deterioration rate (vertical axis on the left), and the peel strength of the second bonding of the coated wire (vertical axis on the right). It is an experimental result showing a relationship.

The peel strength of the 2nd bonding was determined by the inventors of the present invention using a heat-resistant polyurethane-coated wire having a diameter of φ = 25 μm and bonding the coating film 5B to the inner lead 3B without previously peeling off the coating film 5B as shown in FIG. This is the result of performing.

As is clear from FIG. 23, the imidization ratio of the coating film is about
About 1/3 is preferable for both the deterioration rate (deterioration rate) and the peeling strength.

In particular, in the case of the heat-resistant polyurethane-coated wire of the present invention,
Since the peel strength of the 2nd bonding part was large, the reliability of bonding was high and an extremely advantageous result was obtained.

Experimental Example 5 FIG. 24 shows the experimental results on the temperature cycle amplitude (−55 to 150 ° C.) and the temperature cycle life of the coated wire. As is clear from the figure, the service life T の of the coating film made of a commercially available polyurethane is about 400, while that of the heat-resistant polyurethane of the present invention is greatly improved to 4000 or more.

Experimental Example 6 FIG. 25 is a diagram showing the results of an experiment on the effect of the presence or absence of a coloring agent on the coating film of a coated wire on the deterioration rate (deterioration rate).

According to the knowledge of the present inventors, when performing bonding using the covered wire 5, for example, when forming a metal ball, the thickness of the covering film 5 </ b> B is very small, and therefore, the presence or absence of melting or peeling thereof is determined. Is very difficult to verify,
At least it's impossible with the naked eye. Thus, the present inventors have found that if a coloring agent such as oil scarlet is added to the coating film 5B, the melt-up or peeling thereof can be visually confirmed (for example, by using an electron microscope), and it is extremely useful. It is.

However, if the amount of the coloring agent added is too large, the deterioration rate (deterioration rate) of the coating film increases, and the present inventors conducted various experiments on the appropriate amount, and as a result, Is shown in FIG.

As is clear from the experimental results in FIG. 25, when the amount of the colorant added is too large, the deterioration rate (deterioration rate) of the coating film increases, while when the amount of the colorant is too small, the above-mentioned results are obtained. The advantage of such a colorant addition is lost. In view of these two conflicting requirements, the present inventors have studied and found that the addition amount of the coloring agent (oil scarlet in Example 1) was 20% by weight or less, particularly 0.5% by weight to 2.0% by weight. Was found to be optimal.
By adding a coloring agent to the coating film in this range, it is possible to visually confirm melting and peeling of the coating film 5B from the coating wire 5 while preventing the characteristics of the coating film from being impaired. Is obtained.

The present inventors have obtained the following findings through Experimental Example 1 described above, Experimental Examples 2 to 6, and various other experiments, studies, studies, and confirmations.

That is, as described above, the use of the heat-resistant polyurethane having the above composition of the present invention as the coating film 5B of the coating wire 5 is extremely useful for improving the thermal degradation of the coating film, the bonding property, and the bonding peeling strength. is there.

In addition to this, as is apparent from, for example, Experimental Example 2, a temperature cycle test of the coating film 5B and a wear test under the experimental conditions shown in FIG.
The degradation rate in reducing the number of coating film breakage after 20 hours
It is extremely important to use a material that can be formed within a range of 0.1% as a constituent material of the coating film 5B.

In addition, as a characteristic to be provided as a coating film, it is also very important that the coated wire does not cause a problem in bonding property when the coated wire is put to practical use in a wire bonding operation. The present inventors have studied this point, the coating film, for example, when forming a metal ball in ball bonding, or at the time of heat removal of the coating film,
It has been found that it is important to configure the material with non-carbonizing properties.

The reason is as follows. In other words, the coating film melts immediately above the metal ball when forming the metal ball or removing the coating film by heating, but if the coating film is carbonized, the coating film is decomposed by the heating temperature at that time, for example, a high temperature of 1060 ° C. Instead, it is carbonized. As a result, the carbonized coating film 5B
Is attached to the metal ball 5A1 so as to wrap the metal wire 5A immediately above the metal ball 5A1. Therefore, when bonding is performed with the bonding tool 16, the adhered carbonized coating film is supplied by the coated wire 5 passing through the bonding tool 16. Foreign matter 5D that hinders the movement. Such an adsorbed foreign matter 5D is shown in FIG.
Although it can be removed from the surface of the coated wire 5 by the ultrasonic vibration described in the above section, such a carbonized coating film is not generated.

Considering such facts comprehensively, as the coating film of the coated wire, the deterioration rate under the above-mentioned predetermined conditions, that is, in the reduction of the number of times of coating film destruction after 100 hours at 150 ° C. to 175 ° C. It is extremely important that the deterioration rate is within 20% and that these two requirements are non-carbonized at the time of forming the metal ball or removing the coating film by heating. Gave very satisfactory results as a coated wire.

According to the study results of the present inventors, the heat-resistant polyurethane having the above composition satisfies these two conditions.

As described above, the heat-resistant polyurethane constituting the coating film 5B is obtained by reacting a polyol component with an isocyanate, and has a molecular skeleton containing a structural unit derived from terephthalic acid.

Since the coating film 5B made of the heat-resistant polyurethane suppresses the occurrence of film destruction due to thermal deterioration, it is suitable for preventing an electrical short failure such as a tab short, a chip short, or a short between wires of the coated wire 5. ing.

Further, the above heat-resistant polyurethane as the coating film 5B can be bonded by decomposing the urethane bond even at the bonding temperature during normal wire bonding or the ultrasonic vibration energy by the bonding tool 16, so that the heat generated by normal heating can be obtained. Reliable bonding can be obtained by using both pressure bonding and ultrasonic vibration or by ultrasonic vibration. In this case, as described with reference to FIG. 1A, more reliable wire bonding can be performed by using local heating of the bonding site using a heating source such as the heater 26.

Further, as the coating film 5B of the coating wire 5, 150 ° C. to 175
Degradation rate in reduction of the number of times of coating film destruction after 100 hours at ℃ is within 20%, and non-carbonized material is used when forming metal balls 5A1 or destructing / removing coating film 5B. Since thermal deterioration of the film 5B can be prevented, it is possible to prevent electrical short-circuit failure due to film destruction.

Next, the heat-resistant polyurethane used for the coating film 5B of the coated wire 5 in the present invention will be described in more detail. The heat-resistant polyurethane is obtained by reacting a polyol component with an isocyanate, and its molecular skeleton is derived from terephthalic acid. This heat-resistant polyurethane is obtained by using a polymer component having a terephthalic acid-based polyol containing active hydrogen as a main component, and isocyanate. Here, “consists of a main component” is intended to include a case where the whole is composed only of a main component.

Terephthalic acid-based polyol containing the active hydrogen, terephthalic acid and polyhydric alcohol, using OH / COO
It can be obtained by a conventional esterification reaction with H = 1.2-30 and a reaction temperature of 70-250 ° C. In general, those having an average molecular weight of 30 to 10,000 and having about 100 to 500 hydroxyl groups and having hydroxyl groups at both ends of the molecular difference are used.

Raw materials constituting such a terephthalic acid-based polyol include ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol,
Hexane glycol, butane glycol, glycerin,
Aliphatic glycols such as trimethylolpropane, hexanetriol and pentaerythritol;
In addition, polyhydric alcohols such as 1,4-dimethylolbenzene can be mentioned. In particular, it is preferable to use ethylene glycol, propylene glycol, and glycerin.

Terephthalic acid is used as the dicarboxylic acid. If necessary, amic acid and imidic acid can be used in combination.

 The structural formula of the imidic acid is as follows.

Further, dibasic acids such as isophthalic acid, orthophthalic acid, succinic acid, adivisic acid and sebacic acid, 1,2,3,4-butanetetracarboxylic acid, cyclopentanetetracarboxylic acid, ethylene Polybasic acids such as tetracarboxylic acid, pyromellitic acid and trimellitic acid may be used in combination.

As the isocyanate to be reacted with the terephthalic acid-based polyol, the isocyanate group of a polyvalent isocyanate having at least two isocyanate groups in one molecule such as toluylene diisocyanate and xylylene diisocyanate is converted into a compound having active hydrogen, for example, phenol. , Caprolactam and those blocked with methyl ethyl ketone oxime.
Such isocyanates are stabilized. Further, a compound obtained by reacting the above polyvalent isocyanate compound with a polyhydric alcohol such as trimethylolpropane, hexanetriol or butanediol and blocking with a compound having active hydrogen may also be used.

Examples of the isocyanate compound, manufactured by Nippon Polyurethane Co., Millionate MS-50, Coronate 2501,250
3,2505, Coronate AP-St, Death Module CT-St and the like. It is preferable to use a polyisocyanate having a molecular weight of about 300 to 10,000.

The present invention is to prepare a coating composition using the above-described raw materials, apply the coating composition to the metal wire 5A of the wire body, and form a coating film 5B having a thickness of several μm, thereby forming the metal wire of the wire body.
This is to obtain a coated wire 5 insulated around 5A.

As the coating composition, the hydroxyl group 1 of the polyol component is used.
Per equivalent, isocyanate groups of the stabilized isocyanate
0.4 to 4.0 equivalents, preferably 0.9 to 2.0 equivalents and a required amount of a curing accelerator are added, and an appropriate amount of an organic solvent (phenols, glycol ethers, naphtha, etc.) is further added. % By weight. At this time, if necessary, an appropriate amount of an additive such as an appearance improving agent and a dye can be blended.

In the present invention, the isocyanate group of the stabilized isocyanate is 0.4 to 0.4 per hydroxyl equivalent of the polyol component.
The reason for adding 4.0 equivalents is that if it is less than 0.4 equivalents, the crazing characteristics of the resulting insulated wire will decrease, while the wear resistance of the coating film exceeding 4.0 equivalents will be inferior. The curing acceleration catalyst added at the time of preparing the coating composition is preferably 0.1 to 10 parts by weight per 100 parts by weight of the polyol component. When this is less than 0.1 part by weight, the tendency to deteriorate the film-forming ability as well as the curing promoting effect is reduced,
Conversely, if the amount exceeds 10 parts by weight, the heat-resistant urethane bonding wire obtained will have reduced thermal degradation characteristics.

Examples of the curing acceleration catalyst include metal carboxylic acids, amino acids, and phenols.Specifically, naphthenic acid, octenoic acid, zinc salts such as persatic acid, iron salts, copper salts, manganese salts, cobalt salts, A tin salt, 1,8 diazabicyclo (5,4,0) undecene-7,2,4,6 tris (dimethylaminomethyl) phenol is used.

It can be obtained by applying the above-mentioned coating composition on the surface of the metal wire 5A of the wire main body and baking it with a conventional baking coating apparatus.

The coating and baking conditions vary depending on the amounts of the polyol component, the stabilized isocyanate, the polymerization initiator and the curing accelerator, but are usually about 200 to 300 ° C. for about 4 to 100 seconds. In short, the coating is baked at a temperature and for a time sufficient to substantially complete the curing reaction of the coating composition, and the coated wire 5 of this embodiment is obtained.

According to the study results of the present inventors, in addition to the heat-resistant polyurethane having the above-described composition, a commercially available polyurethane and formal satisfy the non-carbonizing requirement, but the coating after 1 hour at 150 ° C. to 175 ° C. Since the rate of deterioration under the above conditions in reducing the number of times of film destruction exceeds 20%, it is not suitable as a coating film.

On the other hand, polyimide, polyamide, nylon, polyester, polyamide imide, polyester imide and the like exhibit carbonization when forming metal balls or when the coating film is removed by heating, so that they are unsuitable for use as a coating film for a coated wire. It turned out that there was.

The coated wire 5 obtained through the above process has its first (1st = 1) bonding side, that is, the connection side between the external terminal 2C of the semiconductor chip 2 and one end of the coated wire 5 formed by ball bonding by forming metal balls 5A1. On the other hand, the second (2 = 2nd) bonding side, that is, the connection between the inner lead 3B of the lead 3 and the other end of the covering wire 5 is formed by so-called thermosonic bonding using thermocompression bonding and ultrasonic vibration. It is conductively connected as the second bonding portion 5A2 without removing the coating film 5B in advance.

Thus, the wire-bonded semiconductor chip 2, the tab 3A of the lead 3, and the inner lead 3B
And the covering wire 5 are sealed with a resin material 6 such as an epoxy resin, for example, and only the outer leads 3C of the leads 3 protrude outside the resin material 6.

Next, the configuration and operation of the wire bonding apparatus for bonding the covered wire 5 in the present embodiment will be described in the second.
The description will be made mainly with reference to FIG. 4 and FIGS.

This wire bonding apparatus is configured as a so-called ball bonding apparatus. As shown in FIG.
The coating wire 5 wound around is supplied to the bonding portion 12.

That is, the supply of the covering wire 5 from the wire spool 11 to the bonding portion 12 is performed by the tensioner 13 and the sprocket 1.
4, Clamper 15 and bonding tool (capillary)
This is done through 16. In this embodiment, the bonding tool 16 is obtained by cutting ruby into the shape shown in FIG. 1 (b), and has a through hole 16B penetrating in the axial direction. As shown in FIG. 1 (b), a conductive material 16C is applied to the inner peripheral surface of the through hole 16B. The conductive substance 16C
Is, for example, aluminum (Al) or chromium (Cr)
Are applied by means such as plating or vapor deposition. When the covered wire 5 passes through the bonding tool, the outer peripheral portion of the covered wire 5 is brought into contact with the surface of the conductive material 16C, The structure is such that static electricity charged on the coating film 5B of the coating wire 5 can be removed. The bonding tool 16 is preferably the ruby in view of durability, but it is needless to say that the bonding tool 16 may be made of a conventional ceramic.

The resin-sealed semiconductor device 1 before resin-sealing is disposed in the bonding portion 12 located below the bonding tool 16 in a positional relationship shown in FIGS. 2 and 4. The resin-sealed semiconductor device 1 before resin sealing is
As shown in FIG. 2, the lower surface (the surface on which the semiconductor chip 2 is not mounted) is supported by a bonding stage 17 of a bonding apparatus.

An external terminal 2C of the semiconductor chip 2 has a coating wire 5
Metal wire 5A that is exposed by removing the coating film 5B on one end side of
The metal ball 5A1 formed by melting the tip of is joined. The metal ball 5A1 has a diameter that is, for example, about two to three times larger than the diameter of the metal wire 5A. On the other hand, the inner lead 3B of the lead 3
The metal wire 5A in a state where the coating film 5B on the other end side of the coating wire 5 at the connection portion is broken and exposed is joined. That is, the other end side of the coating wire 5 is configured such that substantially only the coating film 5B at the connection portion with the lead 3 is removed, and the other coating film 5B remains. The coating film 5B at the other end of the coating wire 5 can be destroyed by ultrasonic vibration, appropriate pressurization, and appropriate heating (energy) provided by the bonding tool 16, as described later.

As described above, in the resin-sealed semiconductor device 1 of the present embodiment using the covering wire 5, the external terminals 2C of the semiconductor chip 2 are provided.
Is connected to a metal ball 5A1 formed by a metal wire 5A on one end side of the covering wire 5, and to an inner lead 3B of the lead 3,
The metal wire 5A on the other end side of the coated wire 5 in which the coating film 5B of the contact portion is broken is connected. Here, since the shape of the metal ball 5A1 is large, the contact area between the external terminal 2C of the semiconductor chip 2 and the metal wire 5A of the covering wire 5 is increased, and the bondability between the two is improved. In addition, the covering wire 5 other than the portion connected to the inner lead portion 3B of the lead 3
Is covered with a coating film 5B, and a short circuit between the other end of the coated wire 5 and the other end of the adjacent coated wire 5 can be reduced. In addition, it is possible to increase the number of terminals (so-called, more pins) of the resin-encapsulated semiconductor device 1.

As shown in FIGS. 2 and 4, a tip portion of the bonding tool 16 and the covering wire 5 in the supply direction (a portion where the metal ball 5A1 is formed) is covered by the covering member 18A when the metal ball 5A1 is formed. Is configured. The covering member 18A is configured to rotate in the direction of arrow A shown in FIG. That is, the covering member 18A
When the metal ball 5A1 is formed, the bonding tool 16 is inserted from the tool insertion opening 18B by a rotating operation in the direction of arrow A, and covers the metal ball 5A1.

This covering member 18A is shown in FIG. 5 (partial sectional view showing a specific configuration, corresponding to a section taken along the line VV in FIG. 6), and FIG. 6 (viewed from the direction of arrow VI in FIG. 5). FIG. 7 (a plan view) and FIG. 7 (a cross-sectional view taken along line VII-VII in FIG. 6).
It is configured as shown in FIG. As will be described later, the coating member 18A is configured such that a part of the coating film 5B does not scatter to the bonding portion 12 due to the blowing of the melting coating film 5B when the metal ball 5A1 is formed. When the metal wire 5A of the coating wire 5 is formed of a material that is easily oxidized such as Cu or Al, the coating member 18A is configured to easily maintain an oxidation-preventing gas atmosphere (shield gas atmosphere). . Such a covering member 18A is formed of, for example, stainless steel. Further, the covering member 18A may be formed of a transparent glass material so that an operator can confirm the formation state and the like of the metal ball 5A1 of the covering wire 5.

As shown in FIGS. 2, 4 and 5, an electric torch (arc electrode) 18D is provided on the bottom of the coating material 18A.
Is provided. The electric torch 18D is, as shown in FIG. 8 (a schematic configuration diagram illustrating the principle of forming a metal ball),
Close to the metal wire 5A on the tip side on the supply side of the coated wire 5,
An arc Ac is generated between the two to form a metal ball 5A1. The electric torch 18D is formed of, for example, tungsten (W) that can withstand high temperatures.

Electric torch 18D is a suction device 1 made of conductive material
It is connected to the arc generator 20 via a suction pipe 18E to the pipe 9. The suction tube 18E is made of, for example, stainless steel, and fixes the electric torch 18D with an adhesive metal layer such as an Ag-Cu brazing material interposed therebetween. The suction tube 18E is fixed to the covering member 18A with the holding member 18F interposed therebetween.
That is, the electric torch 18D, the suction tube 18E and the covering member 18A
And are integrally formed.

The electric torch 18D is close to the tip of the supply side of the covering wire 5 when forming the metal ball 5A1 as described above,
In order to be able to be separated from the supply path of the covering wire 5 during the bonding process, it is configured to be movable in the direction of arrow A shown in FIG. The moving device for moving the electric torch 18D mainly includes the suction pipe 18E and the insulating member 1
Support member 18G that supports electric torch 18D with 8H interposed,
Crankshaft 1 for rotating this support member 18G in the direction of arrow A
8I, and a drive source 18K for rotating the crankshaft 18I. The rotation of the crankshaft 18I
The driving is performed by the movement of the shaft 18J of the drive source 18K in the direction of the arrow B. Drive source 18K is formed of, for example, an electromagnetic solenoid. Although not shown, the crankshaft 18I is rotatably supported by the bonding apparatus main body. The movement of the electric torch 18D and the covering member 18A
Since both are configured integrally, they are performed in synchronization.

As shown in FIG. 4, the arc generator 20 mainly includes a capacitor C1, a capacitor C2 for storage, a thyristor D for arc generation operated by a trier, and a resistor R. The DC power supply DC is configured to supply a negative polarity voltage of, for example, about -1000 to -3000 [V]. The DC power supply DC is connected to an electric torch 1 via a thyristor D, a resistor R, etc.
Connected to 8D. The reference potential CND is, for example, a ground potential (= 0 [V]). In the figures, V is a voltmeter, and A is an ammeter.

As will be described later in detail, the end of the metal wire 5A of the covering wire 5 wound around the wire spool 11 is connected to the reference potential GND. As a result, when the metal ball 5A1 is formed at the tip of the covered wire 5 by the electric torch 18D, as shown in FIGS. 2, 4 and 8, the electric torch 18D is set to the negative potential (-) The metal wire 5A at the tip in the supply direction of 5 can be set to a positive potential (+).

Thus, the arc Ac is generated between the metal wire 5A at the tip of the covered wire 5 and the arc electrode 18D, and the covered wire 5
In the bonding apparatus in which the metal ball 5A1 is formed at the tip of the wire, the metal wire 5A of the coating wire 5 is connected to a positive potential (+), and the electric torch 18D is connected to the negative potential (-). The generation position of the arc Ac generated between the metal wire 5A and the electric torch 18D can be stabilized as compared with the case of the opposite polarity, so that the arc Ac becomes the rear end of the metal wire 5A of the coated wire 5. Crawling up to the side can be reduced. The reduction in the crawling of the arc Ac has a remarkable effect as the reduction in the melting of the coating film 5B of the coating wire 5, and the occurrence of the resin pool due to the melting of the coating material can be prevented.

Note that the present invention connects the metal wire 5A of the coated wire 5 to a voltage higher or lower than the reference potential GND so that the metal wire 5A of the coated wire 5 has a positive potential with respect to the electric torch 18D. You may.

The wire spool 11 around which the covering wire 5 is wound.
Is configured as shown in FIG. 4 and FIG. 9 (exploded perspective view of a main part). The wire spool 11 is formed by, for example, performing alumite treatment on the surface of a cylindrical aluminum metal. The alumite treatment is performed to improve mechanical strength and prevent scratches. This wire spool 11
Has an insulating property because it is anodized as described above.

The wire spool 11 may be plated with chromium (Cr) to have conductivity.

Further, the wire spool 11 can be made of stainless steel.

The wire spool 11 is attached to a spool holder 21 and attached to the bonding apparatus main body 10 by a rotation shaft 21A of the spool holder 21.

The spool holder 21 is made of, for example, a grounded stainless steel so that at least a part thereof has conductivity. Therefore, in the coated wire 5 wound around the spool holder 21, the static electricity charged in the coating film 5B is discharged through the stainless steel.

The wire spool 11 is provided with a connection terminal 11A, as shown in FIGS. 9 and 11 (an enlarged perspective view of a main part). The connection terminal 11A is provided in a point shape on a side surface portion (a flange portion) of the wire spool 11 that comes into contact with a conductive portion of the spool holder 21.

As shown in FIG. 10, the connection terminal 11A is configured such that a conductor 11Ab is provided on an insulator 11Aa, and a connection metal part 11Ac is provided on the conductor 11Ab. The insulator 11Aa is reliably electrically separated from the conductor 11Ab and the wire spool 11,
In addition, it is formed of, for example, a polyimide resin so as to have appropriate elasticity so that the connection metal portion 11Ac can surely contact the spool holder 21. The conductor 11Ab is formed of, for example, Cu foil so that the connection metal portion 11Ac connecting the metal wire 5A of the covering wire 5 and the connection metal portion 11Ac contacting the spool holder 21 can be reliably connected. The connection metal part 11Ac is formed of a conductive paste, solder, or the like.

The connection terminal 11A passes through a notch formed in the side surface (flange) of the wire spool 11 to pass through the metal wire 5 at the end of the covered wire 5 opposite to the side supplied to the bonding portion 12.
A, that is, the metal wire 5A at the winding start end of the covering wire 5 is connected. The metal wire 5A is connected to the connection terminal 11A by the connection metal part 11Ac. The coating film 5B on the surface of the metal wire 5A at the beginning of the winding of the coating wire 5 is heated or chemically removed. The connection terminal 11A, that is, the metal wire 5A of the covering wire 5 is supplied to the reference potential G through the spool holder 21, its rotating shaft 21A and the bonding apparatus main body 10.
Connected to ND. The reference potential GND is the same potential as the reference potential GND of the arc generator 20.

Thus, the connection terminal 11A for connecting to the reference potential GND is provided on the wire spool 11 and the metal wire 5A at the start end of the covering wire 5 is connected to this connection terminal, so that the connection can be made through the spool holder 21 or the like. Since the metal wire 5A of the covered wire 5 can be reliably connected to the reference potential GND because it can be connected to the reference potential GND.

Further, since the metal wire 5A of the covered wire 5 is connected to the reference potential GND, a potential difference between the electric torch 18D and the metal wire 5A of the covered wire 5 on the supply side can be sufficiently reduced when the metal ball 5A1 is formed. As a result, it is possible to improve the generation of the arc Ac, so that the metal ball 5A1 can be reliably formed.

As shown in FIGS. 2 and 4, the bonding tool 16 is supported by a bonding head (digital bonding head) 22 with a bonding arm 16A interposed therebetween. In the bonding arm 16A, an ultrasonic oscillation mechanism 22H with a predetermined frequency is built in at one end on the side of the bonding head 22. The oscillation by the ultrasonic oscillation mechanism 22H causes the bonding tool 16 to ultrasonically oscillate through the bonding arm 16A. It is configured to be.

The bonding head 22 is supported by a base 24 with an XY table 23 interposed. The bonding head 22 is provided with a moving device that can move the bonding arm 16A in the vertical direction (the direction of arrow C in FIG. 2) so that the bonding tool 16 can be moved toward and away from the bonding section 12. The moving device mainly includes a guide member 22A, a vertically moving block 22B, a female screw member 22C, a male screw member 22D, and a motor 22.
Consists of E. The guide member 22A is configured to move the vertical movement block 22B in the direction of arrow C.
The motor 22E is a servomotor, rotates the male screw member 22D by a predetermined amount by applying a predetermined current, and moves the female screw member 22C fitted to the male screw member 22D in the axial direction in accordance with the rotation amount, The vertical movement block 22B interlocked with this movement is configured to move in the direction of arrow C in the figure.

Bonding arm 1 supported by vertical movement block 22B
6A is configured to rotate around a rotation shaft 22F. The rotation of the bonding arm 16A about the rotation axis 22F is controlled by the elastic member 22G. This elastic member 22G
The rotation control is configured to prevent the bonding unit 12 from being pressed more than necessary when the bonding tool 16 comes into contact with the bonding unit 12, and to prevent damage or destruction of the bonding unit 12. I have.

Although not shown in the figure, the rotation of the bonding arm 16A may be performed by swinging of a voice coil motor disposed in the vertical movement block 22B.

The clamper 15 has a structure capable of holding the covering wire 5 from both side surfaces thereof, and is configured to control the supply of the covering wire 5. The clamper 15 is provided on the bonding arm 16A with the clamper arm 15A interposed.

The sprocket 14 is for accurately positioning the coated wire 5 supplied from the wire spool 11 with respect to the bonding tool 16, and is fixed to the clamper arm 15A. In the present embodiment, the clamper 15 and the sprocket 14 are both made of a conductive metal such as stainless steel and are grounded.
Coating film 5B due to abrasion with coated wire 5 when passing through 14
Is prevented from being charged. In addition, when the coating film 5B is charged, a clamper made of the conductive metal is used.
When the outer peripheral surface of the coated wire 5 is brought into contact with the sprocket 15 and the sprocket 14, the static electricity in the charged state is eliminated through the clamper 15 and the proket 14.

As shown in FIGS. 2 and 8, in the vicinity of the leading end of the covering wire 5 in the supply direction and in the vicinity of the supply path of the covering wire 5 between the bonding tool 16 and the bonding portion 12, as shown in FIGS. Cooling fluid spray nozzle of cooling fluid spray device 25
18C is provided. The cooling fluid spray nozzle 18C is connected to the metal ball 5A with the metal wire 5A at the tip of the coating wire 5 in the supply direction.
At the time of forming 1, the cooling fluid (Gs) from the cooling fluid spraying device 25 is sprayed on the formation portion (the metal wire 5A and the coating film 5B). Cooling fluid spray nozzle 18
As shown in FIG. 8, the cooling fluid Gs blown out of C is supplied to the metal ball 5A1 by the metal wire 5A at the tip of the covering wire 5.
Is formed, the coating film 5B that is melted up by the heat generated by the arc Ac is blown off (5Ba), and a resin pool is generated around the coating wire 5 protruding from the tip of the bonding tool 16. And the melting is controlled at a fixed position.

The cooling fluid Gs only needs to spray the cooling fluid Gs in the direction in which the tip of the bonding tool 16 extends, that is, the tip of the coating wire 5. In the present embodiment, the cooling fluid spray nozzle 18 </ b> C Is provided. As shown in FIG. 4 to FIG. 7, the cooling fluid spray nozzle 18C is positioned diagonally above in the figure to reduce the melting of the coating film 5B. The cooling fluid Gs is sprayed from the rear end toward the front end. The cooling fluid spray nozzle 18C
Is preferably not attached to the bonding tool 16. That is, when the cooling fluid spray nozzle 18C is attached to the bonding tool 16, the weight of the bonding tool 16 increases, and the load of the ultrasonic vibration increases, so that the bondability of the connection portion decreases. .

As the cooling fluid Gs, a gas such as N ₂ , H ₂ , He, Ar, or air is used. As shown in FIG. 8, a cooling fluid spraying device (fluid source) 25 sends a cooling device 25A and a flow meter 25B. , Fluid transfer pipe 25
C is supplied to the cooling fluid spray nozzle 18C via C.

At this time, the corona discharge means 25E may be provided in the cooling fluid spraying device 25, and the ion gas (current removing member) in a state where ions are separated may be used as the cooling fluid Gs. In this case, since it is possible to remove the charge of the covering wire 5 immediately before the wire bonding, the semiconductor chip 2 caused by the charging of the covering film 5B at the time of the wire bonding is formed.
Can be effectively prevented from being electrostatically damaged.

Note that according to the study by the present inventors, in addition to the ion gas, also covering layer 5B by blowing the gas by the mere N ₂
Has been confirmed to have a static elimination effect.

The cooling device 25A is configured to actively cool the cooling fluid Gs below normal temperature. The cooling device 25A is configured by, for example, an electronic cooling device using the Peltier effect. Although the fluid transport pipe 25C is shown in a simplified form in FIG. 8, at least the cooling device 25A and the cooling fluid spray nozzle 1
It is configured to cover the space between the supply port of 8C and the heat insulating material 25D. That is, the heat insulating material 25D is configured not to change the temperature of the cooling fluid Gs cooled by the cooling device 25A during movement of the fluid transport pipe 25C (to increase the cooling efficiency).

The suction device 19 is located in the vicinity of the leading end of the covering wire 5 in the supply direction and at a position opposed to the cooling fluid spray nozzle 18C around the melted portion of the covering film 5B of the covering wire 5. Is provided with a suction pipe 18E connected to the suction pipe 18E. The suction tube 18E is connected to the electric torch 1 as described above.
Although it is also used as a conductor for connecting the 8D and the arc generator 20, it is mainly configured to suck the melted coating film 5Ba of the coating wire 5 blown off by the cooling fluid spray nozzle 18C. ing. The coating film 5Ba sucked by the suction pipe 18E is discharged to the outside after being sucked by the suction device 19.

Further, in this embodiment, only the inner lead 3B of the lead 3 is higher than the other parts in order to bond the other end of the covered wire 5 to the inner lead 3B of the lead 3 more reliably (2nd bonding). The heater 26 made of ceramic for locally heating to a temperature is shown in FIG.
It is provided in a square ring shape as shown in the figure. Reference numeral 26A denotes a power supply line to the rectangular ring-shaped heater 26 for local heating.

Next, the wire bonding method of this embodiment will be briefly described.

First, as shown in FIG. 2, FIG. 4, FIG. 5, and FIG. 8, the bonding tool 16 and the leading end portion of the coating wire 5 protruding toward the pressing surface side in the supply direction are coated with a coating member 18.
Cover with A. Such an operation is performed by moving the covering member 18A in the direction of arrow A in FIG. 4 by the moving device operated by the driving source 18K. In addition, this covering member
By using 18A, each of the electric torch 18D and the cooling fluid spray nozzle 18C can be arranged in the vicinity of the tip of the covering wire 5.

Next, as shown in FIG. 8, an arc A is provided between the metal wire 5A at the end of the coating wire 5 in the supply direction and the electric torch 18D.
c is generated, and a metal ball 5A1 is formed by the metal wire 5A. The heat of the arc AC forming the metal ball 5A1 causes the insulating coating film 5B at the tip end in the supply direction of the coating wire 5 to be formed.
Melts up. That is, the coating film 5B at the tip in the supply direction of the coating wire 5 is removed, and the metal wire 5A is exposed.

The formation of the metal ball 5A1 is performed in as short a time as possible.
When the metal ball 5A1 is formed in a short time and with high energy (area where current and voltage are high), the coated wire 5A1
Of the coating film 5B is reduced. in this way,
Performing the formation of the metal ball 5A1 in a short time and with high energy stabilizes the generation of the arc Ac as described above, that is, the electric torch D is set to the negative potential (-) by the metal wire of the covering wire 5.
This can be achieved by setting 5A to a positive potential (+).

When the metal ball 5A1 is formed, the cooling fluid Gs is sprayed from the cooling fluid spraying device 25 onto the coating film 5B, which melts the coating wire 5, by the cooling fluid spraying nozzle 18C whose position is set together with the coating member 18A. As shown in FIG. 8, the coating film 5B is blown off. This blown coating film 5Ba
Is sucked into the suction device 19 through the suction pipe 18E, and is removed out of the system.

The cooling fluid Gs from the cooling fluid spray nozzle 18C is supplied to the cooling device 25A shown in FIG.
It has been cooled to about [° C]. Cooling fluid spray nozzle 18C
The lower the temperature of the cooling fluid Gs is, the smaller the amount of the coating film 5B of the coating wire 5 that has melted is. That is, the cooling fluid Gs cooled by the cooling device 25A can actively cool the metal wire 5A, the coating film 5B, the bonding tool 16 and the like of the coating wire 5, so that only the arc Ac generating portion is coated. The film 5B is melted, and the other part of the coating film 5B is not melted. As a result, the amount of the coating film 5B that has melted can be reduced.

Next, the covering member 18A and the electric torch 1
8D, each of the cooling fluid spray nozzles 18C is moved in the direction of arrow A (the direction opposite to the above).

Next, a metal ball 5A1 formed on the tip of the bonding tool 16 in the supply direction of the covering wire 5 is placed on the pressing surface.
Attraction.

Next, in this state, the bonding tool 16 is moved closer to the bonding portion 12, and the bonding tool 16 is placed on the surface of the external terminal 2C via the metal ball 5A1, as shown by a broken line in FIG. Landed. In this state, the ultrasonic oscillation mechanism 22H in the bonding head 22 is operated to apply ultrasonic vibration of a predetermined frequency to the bonding tool 16 via the bonding arm 16A. The external terminal 2C and the metal ball 5A1 are joined to each other by a synergistic effect of ultrasonic vibration in a heating environment (1st bonding).

Next, while the application of the ultrasonic vibration is continued,
The bonding tool 16 is moved by the drive control of the XY table 23 and the motor 22E along the path shown by the two-dot chain line in FIG.
The covering wire 5 is stretched in a loop between the semiconductor chip 2 and the inner lead 3B by being positioned immediately above 3B and further lowered. At this time, the abdomen of the covered wire 5 led out from the tip of the bonding tool 16 is rubbed against the surface of the inner lead 3B. Here, due to the ultrasonic vibration continuously applied to the bonding tool 16, the coating film 5B of the coating wire 5 in contact with the surface of the inner lead 3B was broken and peeled, and the metal wire 5A was exposed. State. By continuing the ultrasonic vibration, the exposed metal wire 5A is ultrasonically bonded to the surface of the inner lead 3B (2nd bonding).

As described above, in this embodiment, the bonding tool 16 from the first bonding to the second bonding is used.
Is in a state where the application of the ultrasonic vibration is continued during the movement of. Therefore, as shown in FIG. 1B, above the moving bonding tool 16, the covering wire 5 is moved by the ultrasonic vibration of the bonding tool 16.
The wire itself is also in a vibrating state.
Adsorbed foreign matter 5D due to static electricity attached to the periphery of the wire 5 is separated from the surface of the covered wire 5 by the vibration.

As described above, most of the adsorbed foreign matter 5D on the surface of the covered wire 5 is separated and removed before being inserted into the through hole 16B of the bonding tool 16, so that the adsorbed foreign matter 5D
Clogging of the bonding tool 16 due to the above is reliably prevented.

Further, by applying the above ultrasonic vibration, the coated wire 5
In the inside of the through hole 16B inside the bonding tool 16, since it receives ultrasonic vibrations from its surroundings on average,
The displacement of the covering wire 5 in the through hole 16B, that is, the contact with a specific inner wall portion of the through hole 16B is prevented. For this reason, it is possible to prevent the covering wire 5 from being bent (curled) or the like due to long-term contact, and the covering wire 5 can be held in the bonding tool 16 in a straight state. Therefore, at this stage, the bonding failure caused by the curling of the covering wire 5 is also effectively prevented. Further, in this embodiment, as shown in FIG. 1B, the conductive material 16C is formed on the inner wall surface of the through hole 16B of the bonding tool 16.
Is applied, it is also possible to obtain an effect of preventing static electricity of the coated wire 5 and a static elimination effect of the coated wire 5.

Incidentally, the ultrasonic vibration is set at a vibration frequency in a range necessary for removing the coating film 5B in the second bonding and ultrasonic bonding between the exposed metal wire 5A and the inner lead 3B. The oscillation frequency during the movement of the tool 16 and the oscillation frequency during the second bonding may be variably controlled. Also, coating film
The thickness of the 5B wire surface varies slightly depending on the energy of the ultrasonic vibration of the bonding tool 16 and the thermocompression force, but is preferably, for example, about 0.2 to 3 [μm]. When the thickness of the coating film 5B of the coating wire 5 is too small, the withstand voltage as the insulating coating film is small. If the thickness of the coating film 5B of the coating wire 5 is too large, the coating film 5B is less likely to be broken by the ultrasonic vibration of the bonding tool 16, and the coating film 5B has a predetermined value. If it exceeds, the coating film 5B will not be destroyed, resulting in poor connection between the metal wire 5A of the coating wire 5 and the inner lead 3B of the lead 3.

In the present embodiment, when the other end of the covered wire 5 is bonded (2nd bonding), only the inner lead 3B of the lead 3 is locally heated by the heater 26 to a temperature which is particularly higher than that of the other portions. Since the heating / decomposition of the cover film 5B is further promoted, the bondability of the second bonding can be improved, and strong wire bonding can be performed.

After the completion of the second bonding, the bonding tool 16 is raised and separated from the inner lead 3B. At this time, the covering wire 5 is in the middle (bonding tool).
(Above 16) is clamped by the clamper 15, so that it is cut from the rear end of the second bonding, and the wire bonding process of one cycle of the covered wire 5 as shown in FIG. 1 (a) is completed. I do.

Thus, the metal ball 5A1
In the bonding technique for forming the cooling wire, a cooling fluid spraying nozzle 18C (a part of the cooling fluid spraying device 25) for spraying the cooling fluid Gs to the tip of the covering wire 5 is provided near the tip of the covering wire 5. Thereby, the coating film 5B that melts the coating wire 5 can be scattered, so that it is possible to prevent the resin pool from being formed on the coating wire 5 due to the coating film 5B.

As a result, the covering wire 5 is prevented from being caught on the bonding tool 16 due to the resin pool of the insulating covering film 5B, and the covering wire 5 can be drawn more toward the pressing surface of the bonding tool 16. Therefore, good ball bonding can be performed.

Further, the bonding technique for forming the metal ball 5A1 at the tip of the covering wire 5 is provided by providing the cooling fluid spray nozzle 18C (part of the cooling fluid spraying device 25), and in the vicinity of the tip of the covering wire 5, By providing a suction pipe 18E (suction device 19) for sucking the coating film 5B of the coating wire 5 blown off by spraying the cooling fluid Gs from the cooling fluid spray nozzle 18C, the coating film of the coating wire 5 that melts is provided.
5B is blown off to prevent the spheres of the coating film 5B from being formed on the coating wire 5 and to prevent the bonding failure as described above.
Is not scattered to the bonding portion 12, so that a bonding failure caused by the scattered coating film 5Ba can be prevented. The bonding failure caused by the scattered coating film 5Ba is, for example, the external terminal 2C of the semiconductor chip 2 or the inner lead 3B of the lead 3 and the metal wire of the coating wire 5.
This is the case where the coating film 5Ba scatters between the two and 5A, resulting in poor connection between the two.

Further, this is a bonding technique for forming a metal ball 5A1 at the tip end of the covering wire 5, in which the cooling fluid spray nozzle 18C (cooling fluid spray device 25) is provided to cool the cooling fluid Gs of the cooling fluid spray nozzle 18C. By providing the cooling device 25A, the melting of the insulating coating film 5B of the coated wire 5 is significantly reduced.
Since 5B can be blown off, it is possible to prevent the sphere of the coating film 5B from being formed on the coating wire 5 and prevent the bonding failure as described above.

In addition, ion gas (current eliminator) as cooling fluid Gs
By using, the charge can be removed from the coating film 5B of the coating wire 5 and thus, electrostatic breakdown of the semiconductor chip 2 due to the charging of the coating film 5B during wire bonding can be effectively prevented.

In the bonding technique using the covered wire 5, a metal ball 5A
1, the metal ball 5A1 is connected to the external terminal 2C of the semiconductor chip 2, the rear end of the coating wire 5 in the supply direction is brought into contact with the inner lead 3B of the lead 3, and the contact portion is covered. The coating film is removed by breaking the film 5B and connecting the metal wire 5A on the other end of the coating wire 5 to the inner lead 3B of the lead 3 to remove the coating film 5B on the rear end side of the coating wire 5. Since the coating film 5B can be removed without using a torch, it is possible to reduce the coating film removing torch, its moving device, control device, and the like. As a result, the device structure of the wire bonding apparatus can be simplified, and cost reduction in the semiconductor device manufacturing process can be realized.

In addition, since wire bonding using the covering wire 5 can be substantially realized, an external terminal 2C as shown in FIG. As described above, those having at least external terminals requiring a complicated bonding wiring or high-function / high-integration microprocessors or logic elements having a large number of external terminals and requiring complicated bonding wiring such as cross bonding are required. Realization becomes easy.

Further, in the resin-encapsulated semiconductor device 1 of the present embodiment, as the insulating coating film 5B of the coating wire 5, a polyol component and an isocyanate are allowed to react with each other, and a heat-resistant component containing a structural unit derived from terephthalic acid in a molecular skeleton. By using polyurethane, tab shorts, chip shorts, or shorts between wires due to film destruction caused by thermal differentiation of the coating film 5 can be reliably prevented.

That is, after bonding the covering wire 5 as described above, a resin molding operation is performed with the resin material 6 to manufacture the resin-encapsulated semiconductor device 1. For example, as shown in FIG. When the distance between the external terminal 2C of the chip 2 and the bonding portion of the inner lead 3B of the lead 3 is long, as shown in FIG. 13, the so-called chip where the covering wire 5 and the silicon region of the semiconductor chip 2 come into contact with each other. A touch state, a so-called tab touch state in which the covered wire 5 contacts the tab 3A as shown in FIG. 15, and a so-called inter-wire touch state in which the covered wires 5 contact each other may occur. Such a wire touch phenomenon tends to occur particularly when the wire length becomes 2.5 mm or more, or when the size of the tab 3A is larger than the size of the semiconductor chip 2.

When such a wire touch phenomenon occurs, for example, as shown in FIG. 14, the coating film 5B of the coating wire 5 is broken by thermal deterioration caused by heat generation from the semiconductor chip 2, and the metal wire 5A is 2 is in direct contact with the semiconductor chip 2
Or a chip short between them, as shown in Fig. 16,
A tab short failure may occur between the wire and the tab 3A, and a short between wires may occur between wires.

However, in the resin-encapsulated semiconductor device 1 of the present embodiment, as described above, since the coating film 5B of the coating wire 5 is made of a special heat-resistant polyurethane, it is assumed that the chip touch, Even if a tab touch or a wire-to-wire touch occurs, it is possible to reliably prevent a short circuit from occurring.

Next, another modification of the wire bonding method according to the present embodiment will be further described with reference to FIGS.

FIG. 26 shows a ball bonding method using a metal ball 5A1 on the first bonding side of the covered wire 5 as in the first embodiment, but the second bonding side is previously covered before the second bonding as shown in the figure as a second bonding portion 5A22. The cover film 5B is removed, and 2nd bonding is performed by thermocompression bonding and / or ultrasonic vibration.

FIG. 27 shows that the second bonding portion 5A2 is bonded without removing the coating film 5B in the same manner as described with reference to FIG. 1, and the 1st bonding side is not ball-bonded with a metal ball. Without removing the coating film 5B in advance for 1 s by thermocompression bonding and / or ultrasonic vibration.
The first bonding portion 5A11 is formed by t bonding. Therefore, in the same figure, the same bonding method can be used for both the 1st and 2nd bonding.

In FIG. 28, the first bonding portion 5A11 is the same as that in FIG. 27, but the second bonding portion 5a22 is
The same method as in FIG. 6, that is, bonding is performed by removing the coating film 5B in advance.

In FIG. 29, as the first bonding portion 5A12, the coating film 5
B is removed in advance, and the second bonding portion 5A2 is covered with the coating film 5 as in FIGS. 1 (a) and 27.
Bonded without removing B.

FIG. 30 is an example in which the metal wire 5A is bonded by a non-ball forming method in a state where the coating film 5B has been removed in advance in both the first bonding portion 5A12 and the second bonding portion 5A22.

FIG. 31 shows a case where the coating film of the coating wire 5 has a composite coating film structure. That is, the outer surface of the coated wire 5 is coated with the coating film 5B made of the above-described heat-resistant polyurethane, and the outer surface of the coating film 5B is further coated with a second coating film 5C made of another insulating material. This is an example of coating with. This second
As a material of the coating film 5C, a polyamide resin, a special polyester resin, a special epoxy resin, or the like can be used as described above. Further, in order to improve the slip of the coated wire 5 in the bonding tool 16, the second coating film 5C is used.
Can also be applied. For such a purpose, nylon or the like can be used as the second protective film 5C.

In addition, the thickness of the second coating film 5C can be set to twice or less, preferably 0.5 times or less, the thickness of the coating film 5B.

As described above, the invention made by the inventor has been specifically described based on the first embodiment. However, the present invention can be variously modified without departing from the gist thereof.

For example, the bonding tool 16 has been described with reference to a drawing using a capillary, but the present invention is not limited to this, and a knife-shaped wedge may be used. Also in this case, as described in the first embodiment, the application of the ultrasonic vibration is continued during the wire feeding between the first bonding and the second bonding, whereby the clogging of the wire, the removal of the adsorbed foreign matter 5D, or the wire Curling can be prevented, and the same effect as described above can be obtained.

Further, a material for forming the coating film 5B or 5C, for example, a polyol component, isocyanate, terephthalic acid,
Further, the types and compositions of the compounds and the additives, and the additives are not limited to the examples described above.

FIG. 32 is an explanatory view showing a route of a covering wire from a wire spool to a bonding tool in a wire bonding apparatus as an assembling apparatus used in Embodiment 1 of the present invention II, and FIG. 33 is a structure of an airbag tensioner. 34 is a partially cutaway perspective view, FIG. 34 is a side view showing the inner peripheral surface shape of the airbag tensioner, FIG. 35 is a schematic sectional view showing a clamper, and FIG. 36 shows the vicinity of the clamper. 37 is an enlarged perspective view, FIG. 37 is a schematic plan view showing a driving mechanism of the clamper, FIG. 38 is a schematic sectional view of a conventional clamper for comparison with FIG. 35, and FIG. 39 is wire bonding in the present embodiment. FIG. 40 is an explanatory plan view of a lead frame showing a wire bonding state according to the present embodiment, and FIG. 41 is a resin-encapsulated semiconductor obtained by the present embodiment. It is an overall cross sectional view of the location 33.

In the present embodiment, the structure of the wire bonding apparatus itself is almost the same as that shown in FIG. 2 in I of Embodiment 1 described above.
The feature is that the static elimination means provided between 11 and the bonding tool 16 is different.

That is, the covering wire 5 supplied from the wire spool 11 is inserted into the bonding tool 16 via the airbag tensioner 31, the sprocket 14, and the clamper 32.

The airbag tensioner 31 has a pair of guide plates 31A as shown in FIG. This guide plate 3
1A may be an aluminum alloy surface that has been subjected to alumite treatment. However, by forming at least the contact surface with the coated wire 5 with a conductive metal, a structure that can prevent charging of the coated wire 5 at the time of contact. ing. Further, not only the contact surface but also the entire guide plate 31A may be made of stainless steel or the like.

As shown in FIG. 34, a plurality of projections 31B are formed on the surface of the guide plate 31A of the present embodiment on the wire passage space 31G side, as shown in FIG. Such a protrusion 31B
As a technique for obtaining the structure of the above, by using a processing technique such as pressing, the inner peripheral surface of the guide plate 31A may be processed into a protruding shape, or may be joined to the inner peripheral surface of the guide plate 31A formed flat. The rod-shaped member may be fixed using a means such as bonding.

As described above, in the present embodiment, by providing the protrusion 31B extending in the direction substantially perpendicular to the direction in which the covering wire 5 passes on the inner peripheral surface of the guide plate 31A, the covering when passing through the airbag tensioner 31 is provided. The contact between the outer peripheral surface of the wire 5 and the inner peripheral surface of the guide plate 31A is substantially in a point contact state, and by reducing the contact area, friction can be suppressed and the outer peripheral surface of the covered wire 5 can be prevented from being charged.

A metal adapter 31D connected to a fluid supply pipe 31C is mounted on one longitudinal end of both guide plates 31A, and a fluid outlet 31E is opened on an end surface of the adapter 31D. A flat spacer 3 is provided around the fluid outlet 31E.
1F is formed so as to protrude, and the width of the wire passage space 31G is determined by the thickness of the spacer 31F. The width of such a wire passage space 31G varies depending on the diameter of the covering wire 5 used or the height of the projection 31B from the inner surface of the guide plate 31A, but is about 1 mm in the present embodiment.

The fluid supply pipe 31C connected to the adapter 31D is connected to a fluid supply source 31H. The fluid supply source 31H has, for example, a built-in corona discharge means 31H1, whereby ion-separated ion gas is supplied to the wire passage space 31G from the outlet 31E of the adapter 31D as a current eliminator Gs2. ing.

Therefore, according to the present embodiment, the supply of the current eliminator Gs2 to the wire passage space 31G causes the airbag tensioner 3
It is possible to apply the back tensioner of the covered wire 5 which is the original purpose, and at the same time, it is possible to remove the electrostatic charge of the covered wire 5. Further, as described above, the contact between the covering wire 5 and the airbag tensioner 31 is substantially point contact due to the structure of the projection 31B on the inner peripheral surface of the guide plate 31A. Of the outer peripheral surface is also suppressed.

The clamper 32 located below the airbag tensioner 31 has a pair of clamper arms 32A as shown in FIGS. 36 and 37, and the clamper arm 32A passes through a shaft support 32B. The front end side can be opened and closed by the operation of the cow mechanism 32C engaged at the rear end side (FIG. 37). The pair of clamper arms 32A1, 3A
2A2 is normally urged by a spring 32D or the like in a direction in which the tip is closed, and the cam mechanism 32C is actuated from this state to cause the clamper arm 32A to operate.
The distal ends of 1, 32A2 are configured to move away from each other to open the clamper 32.

A first clamper chip 32E1, which is made of a hard metal such as stainless steel and whose surface is mirror-finished by chrome plating or the like, is fixed inside the tip of one clamper arm 32A1 (fixed side). In the chip surface of the first clamper chip 32E1, an outlet 32F of the current eliminator Gs2 as shown in FIGS. 35 and 36 is opened substantially at the center thereof.
32F is communicated with the fluid supply tube 31C connected to a fluid supply source 31H, for example, ion gas or the spraying of neutralizing fluid Gs2 such as N ₂ gas, it is possible. The fluid supply source 31H incorporates the corona discharge means 31H1 as described in the description of the airbag tensioner 31 described above.

A leaf spring-like sub-arm 32G having a predetermined elasticity is attached to the tip of the other clamper arm 32A2 (movable side) with its base fixed with screws 32H or the like. A second clamper chip 32E2 made of ruby or the like is fixed. The second clamper arm 32E2 is detachable from the clamper arm 32A2 in units of sub-arms 32G, and can be replaced in units of sub-arms 32G when wear occurs due to a predetermined number of clamping operations. I have. With such a structure of the leaf spring-like sub-arm 32G, the load force on the side surface of the covered wire 5 at the time of clamping the covered wire 5 is controlled, so that the covered wire 5 is prevented from being damaged.

Note that a chip-shaped stopper 32J is fixed on the back side of the second clamper chip 32E2, that is, inside the movable clamper arm 32A2.

The positional relationship between the clamper 32 and the covering wire 5 is as follows.
As shown in FIG. 36 and FIG. 36, the covering wire 5 from the sprocket 14 to the bonding tool 16
The second clamper chips 32E1 and 32E2 are arranged so as to pass through substantially the center between the opposing chip surfaces. Here, as shown in FIG. 35, a current eliminator Gs2 is constantly blown out from an outlet 32F opened on the chip surface of the first clamper chip 32E1, and this current eliminator Gs2, for example, The ion gas passes through the coating wire 5 and the chip surface of the second clamper tip 32E2, so that the coating wire 5 and the second clamper tip 32
Static electricity charged on the chip surface of E2 is removed. According to experiments performed by the present inventors, it has been confirmed that a static elimination effect can be obtained by spraying an N ₂ gas or the like in addition to the ion gas as the current eliminator Gs2.

Note that the outlet 32F need not always be arranged at the center of the clamper chip surface of the first clamper chip 32E1 if static elimination is performed only on the chip surface of the clamper chip 32E2. It is possible to blow the current eliminator Gs2 also to the side surface of the wire 5. As a result, it is possible to remove the static electricity from the coated wire 5 and to scatter and remove the adsorbed foreign matter 5D such as a small piece attached to the side surface of the coated wire 5, and to clean the coated wire 5. For this reason, in the present embodiment, it is possible to effectively prevent clogging and the like in the bonding tool 16 caused by the adsorbed foreign matter 5D adsorbed on the coated wire 5, and as a result of extending the maintenance cycle of the bonding tool 16, the efficiency is improved. It is also possible to realize the production of the resin-encapsulated semiconductor device 33. In the second embodiment, as described above,
Since the electrostatic charging of the ruby clamper chip 32E2 attached to the tip of the 32G is effectively prevented, the covering wire 5 is inserted before the insertion into the bonding tool 16.
Can be prevented from being curled by being adsorbed by the clamper chip 32E2. That is, in the prior art, as shown in FIG. 38, the covering wire 5 is attracted to the clamper chip 32E2 due to the electrostatic charging of the clamper chip 32E2, and even when the clamper 32 is opened. The covered wire 5 remained curled. . When this is inserted into the bonding tool 16 and wire bonding is performed, the curl shape also affects the loop shape of the wire bonding, and the external terminal 2C (bonding pad) or the inner lead 33B and the coated wire 5
This results in a decrease in bonding strength with the wire and a wire flow at the time of resin molding due to a loop abnormality. Further, since the covered wire 5 is attracted to the charged clamper chip 32E2, the covered wire 5 is not smoothly fed out from the bonding tool 16 during wire bonding, and the bonding wire 5 is connected to the bonding tool 16 as described at the beginning of this specification. When the tool 16 is lowered, the bonding tool 16
As a result, an extra resistance force is added to the wire, and when the covered wire 5 is stretched while drawing the covered wire 5 from the tip of the bonding tool 16, there is a possibility that the covered wire 5 may be disconnected or a loop abnormality may occur. there were. In this regard, according to II of the first embodiment, since the static elimination of the clamper chip 32E2 is reliably performed, the attraction of the coated wire 5 to the clamper chip surface is prevented. As shown in FIG. 36 and FIG. 36, it is inserted into the bonding tool 16 in a straight state and smoothly.

For this reason, a bonding failure due to a loop abnormality due to disconnection or curling of the covered wire 5 is effectively prevented. According to the study of the present inventors, the adsorption of the covered wire 5 due to the electrification of the clamper chip 32E2 (No.
FIG. 38) is a phenomenon that occurs remarkably in the covered wire 5 having the same structure as that described in the example 1 I.
Not only the coated wire 5 but also gold (A
u), aluminum (Al) or copper (Cu) has been found to be highly likely to occur even when used as a wire.

Next, the structure of the resin-sealed semiconductor device 33 assembled in II of the first embodiment will be briefly described.

In II of the first embodiment, the resin-encapsulated semiconductor device 33 is provided in a state before assembly, that is, in a state of the lead frame 33A. FIG. 40 shows a state in which wire bonding has already been completed. For convenience, the structure of the inner lead 33B of the lead frame 33A will be described with reference to FIG. As shown in the figure, the lead frame 33A is provided with inner leads extending in four directions in a plane 4 in a non-contact manner with the tab 33D centered on a tab 33D supported substantially at the center by a tab suspension lead 33C. 33B. The respective inner leads 33B are in a state of being connected to each other by a frame (not shown) at a further outer peripheral portion shown in FIG. Such a lead frame
33A is obtained by processing a plate-like member having a thickness of about 0.15 mm, such as Kovar, 42 alloy or nickel alloy, into a shape shown in FIG. 40 through pressing or etching.

On the tab 33D, as shown in FIG. 39, a thickness of 30 μm
The semiconductor chip 2 is fixed via a bonding material 4 such as a silver paste, a silicon paste or a gold foil, which is applied to a certain extent. Although not shown in detail, a microprocessor, a logic circuit, or the like is formed in an upper layer of the semiconductor chip 2 through an oxidation / diffusion process using a photoresist technique. Briefly describing the schematic configuration of each layer inside the semiconductor chip 2, a silicon oxide film 2A2 of about 0.45 μm is formed on an upper layer of a chip substrate 2A1 made of silicon (Si) having a thickness of about 400 μm.
In addition, the PSG film 2A3 as an interlayer insulating film is
It is formed with a thickness of about μm. On the uppermost layer, a passivation film 2B as a protective film is deposited with a thickness of about 1.2 μm, a part of which is opened and has a thickness of 0.8 μm made of aluminum (Al) partially provided in the lower layer.
About m external terminals 2C expose the upper surface to the outside.

Next, a wire bonding procedure according to the present embodiment will be described. In the following description, it is assumed that the structure of the wire bonding apparatus other than that shown in FIG. 32 is the same as that of FIG.

First, when the lead frame 33A is fixed at a predetermined position on the stage surface of the bonding stage 17, the heat of the heater 26 built in the bonding stage 17 is transmitted to the lead frame 33A, and the lead frame 33A and the semiconductor chip 2 Is increased to a predetermined bonding condition temperature.

Subsequently, the XY table 23 is operated to activate the bonding head.
The bonding tool 16 is stopped at a position immediately above the semiconductor chip 2 on the lead frame 33A by moving the bonding tool 22 by a predetermined amount.

At this time, the clamper 32 holds the covering wire 5 from the side, and the position of the covering wire 5 is fixed by this.

Subsequently, the electric torch 18D as shown in FIG.
As shown in FIG. 8 (a schematic configuration diagram illustrating the principle of formation of the metal ball 5A1), the metal wire 5A is brought close to the metal wire 5A on the tip side on the supply side of the coated wire 5, and an arc Ac is generated between the two. 5A1 is formed. Then, bonding tool 1
Ultrasonic vibration is applied to 6 and the bonding tool 1
6 is pressed against the external terminal 2C of the semiconductor chip 2 so that the metal ball 5A1 is bonded onto the external terminal 2C by a synergistic effect of the heating of the heater 26 and the ultrasonic vibration (1st bonding). .

Next, when the cam mechanism 32C of the clamper 32 is operated, the respective clamper arms 32A1 and 32A2 are opened, and the covered wire 5 is released from the clamper 32.

At this time, in this embodiment, the static electricity charged in the other clamper chip 32E2 is reliably removed by blowing the current eliminator Gs2 from the outlet 32F of the one clamper chip 32E1, so The curling wire 5 is not substantially curled as shown in FIG.
It is possible to be inserted.

In this state, the vertically moving block in the bonding head 22
When the XY table 23 and the XY table 23 are moved by a predetermined amount in the respective directions, the bonding tool 16 moves the coating wire 5 so as to draw a loop while feeding the coating wire 5 from the tip thereof, and a predetermined inner lead is formed. Stops just above 33B (see Figure 39). At this time, the coated wire 5 sent out from the tip of the bonding tool 16 is supplied from the wire spool 11 and is supplied to the airbag tensioner 31.
In addition, it reaches the bonding tool 16 via the clamper 32. During this time, as shown in FIGS. 33 and 35, the current eliminator Gs is blown (blown) in the airbag tensioner 31 and the clamper 32. During this time, in the second embodiment, the continuous application of the ultrasonic vibration to the bonding tool 16 as described in the first embodiment may be performed, or the application of the ultrasonic vibration may be stopped except during the bonding. .

Next, when the vertical movement block 22B is moved downward again, the tip of the bonding tool 16 lands on the surface of the inner lead 33B while the covered wire 5 is drawn out from the tip.

Subsequently, when the vertical movement block 22B is moved downward again, the tip of the bonding tool 16 lands on the surface of the inner lead 33B with the covering wire 5 pulled out from the tip. Here, when the ultrasonic oscillation mechanism 22H is operated and ultrasonic vibration is applied to the tip of the bonding tool 16 again, the coating applied to the abdomen of the coating wire 5 derived from the bonding tool 16 is applied. The portion of the film 5B is rubbed against the surface of the inner lead 33B, and a part of the coating film 5B is broken / removed by the ultrasonic energy, and the inner metal wire 5A comes into contact with the surface of the inner lead 33B. By continuing the application of ultrasonic vibration in this state, the metal wire 5A and the inner lead 33B are joined as shown in FIG. 39 (2nd bonding).

Next, the clamper 32 is closed and the bonding tool 16 is closed.
When the covering wire 5 is clamped above and the vertical movement block 22B is further moved upward, the covering wire 5 is cut between the bonding portion of the covering wire 5 and the bonding tool 16 to complete one cycle. The wire bonding operation is completed.

The wire bonding process of the present embodiment is completed by repeating the above-described wire bonding operation for a predetermined cycle between all the internal terminals 2C (bonding pads) on the semiconductor chip 2 and the corresponding inner leads 33B.

As described above, in the second embodiment, the airbag tensioner
Since the coated wire 5 is neutralized by the current eliminator Gs2 from the base 31 and the clamper chip 32E2 is neutralized to remove the adsorbed foreign matter 5D and the like, the coated wire 5 is disconnected during wire bonding. , Loop abnormalities and clogging of the bonding tool are reliably prevented.

As described above, according to II of the first embodiment, since wire bonding using the covered wire 5 can be substantially realized, cross-bonding and the like at a portion indicated by a in FIG. -A highly integrated microprocessor or logic element can be realized.

In FIG. 40, since the covered wire 5 is wire-bonded while straddling the tab suspending lead 33C at the location indicated by b in FIG. 40, there is a possibility that the covering wire 5 and the tab suspending lead 33C may come into contact with each other. high. However, even in the case where the coated wire 5 comes into contact with the tab suspension lead 33C, in the second embodiment, the coating film 5B is connected to the tab suspension lead 33C.
Electrical short circuit is prevented only by contact with As described above, according to II of the first embodiment, wire bonding that was difficult with the conventional bare metal wire can be realized.

After the completion of the wire bonding process as described above, the lead frame 33A is placed in a mold (not shown),
The package body 33 of the resin-encapsulated semiconductor device 33 is injected by injecting a high-pressure molten synthetic resin into the mold.
E (see FIG. 41) is formed. At this time, if there is an abnormality such as curl in the loop shape of the bonded coated wire 5, contact (wire short) between the coated wires 5 and contact between the coated wire 5 and the tab 33 D due to the injection pressure of the synthetic resin. The possibility of causing defects such as (tab short) increases. However, according to the present embodiment, in the wire bonding step, as described above, static elimination of the covered wire 5 by the airbag tensioner 31 and static elimination of the clamper chip 32E2 are performed.
And the like, and the adhesion of the covered wire 5 and the attachment of foreign matter during the passage of each part are effectively prevented. Therefore, the bonding failure such as disconnection and the abnormal shape of the wire loop due to these are prevented, and the reliable wire bonding is achieved. Has been realized.

After the injected synthetic resin is cooled and hardened as described above, the lead frame 33A on which the package body 33E is formed is taken out of the mold.

Next, the outer lead 3 protruding from the package body 33E
3G is electrically separated and processed into an independent state, and by further bending the outer lead 33G at a predetermined angle,
A resin-sealed semiconductor device 33 shown in FIG. 41 is obtained.

Although the invention made by the inventor has been specifically described based on the second embodiment, the present invention is not limited to the above-described embodiment, and it can be said that various modifications can be made without departing from the gist of the invention. Not even.

For example, the blow of the current eliminator Gs2 from the outlet 32F
As described in the case of always performing during wire bonding,
The blowing cycle may be controlled by a predetermined time. When the covering wire 5 is reinserted into the bonding tool 16 during maintenance of the apparatus, it goes without saying that the blowing of the current eliminator Gs2 from the outlet 32F is stopped.

In each embodiment, an ion gas subjected to ion separation by corona discharge is used as the current eliminator Gs2 for blowing,
Alternatively, the method using N ₂ gas has been described, but not limited to these, examples of those having a static elimination effect include irradiation with α-rays or β-rays, irradiation with ultraviolet rays, and the like. It is known that electrification can be removed by spraying, and a static elimination means using these may be used.

In the above description, the case where the invention made by the present inventor is mainly applied to a wire bonding apparatus of a combined use type of so-called thermocompression bonding and ultrasonic bonding, which is a field of application, has been described, but is not limited thereto. For example, the present invention can be applied to an ultrasonic bonding type wire bonding apparatus.

The effects obtained by the representative ones of the inventions disclosed in the above embodiments will be briefly described as follows.

That is, during the wire bonding between the electrodes in the semiconductor device assembling process, by continuously applying the ultrasonic vibration of the bonding tool, it is possible to remove the foreign matter in the bonding tool by the vibration. Clogging can be effectively prevented.

By enabling the static elimination of the coated wire, disconnection of the coated wire, loop abnormality, and clogging of the bonding tool during wire bonding can be prevented.

Since a complicated connection shape such as cross-bonding with a covering wire becomes possible, a highly integrated and high-performance semiconductor device as a microprocessor element or a logic element can be realized.

By using the current eliminator as the supply fluid in the airbag tensioner, the application of the wire backtensioner and the elimination of electricity on the surface of the wire can be performed at the same time, and the electrification of the wire can be prevented without complicating the device structure.

The static elimination on the clamper chip surface prevents wire sticking due to charging on the assembly device side, regardless of whether the wire is a covered wire or a bare wire.
Clogging of the bonding tool can be effectively prevented.

As described above, the bonding efficiency in the process of assembling the resin-encapsulated semiconductor device can be improved, and a highly reliable, highly integrated and highly functional semiconductor device can be provided.

(2) Embodiment 2 FIG. 42 is an explanatory view showing a state of application of ultrasonic energy to a bonding tool in an assembling process of a semiconductor device according to Embodiment 2 of the present invention, and FIG. 43 is an entire wire bonding apparatus. Schematic diagram, FIG. 44 is a plan view showing a lead frame used in this embodiment, FIG. 45 is an enlarged partial perspective view showing a surface state of an inner lead in this embodiment,
46 is a cross-sectional explanatory view showing a structure of a semiconductor chip, FIG. 47 is a perspective view showing a wire supply system, FIG. 48 is an enlarged perspective view showing a main part of an airbag tensioner in this embodiment, FIG.
FIG. 49 is a front view of the airbag tensioner, FIG. 50 is an explanatory view showing the arrangement of each mechanism near the bonding tool, FIG. 51 is a cross-sectional perspective view showing the structure of the covering wire, and FIG.
The figure is an explanatory view of the abrasion test, and FIG. 53 is a sectional view showing the entire configuration of the semiconductor device.

The wire bonding apparatus 201 according to the present embodiment is configured such that, when assembling a resin-sealed semiconductor device 202 having a resin-sealed package structure as shown in FIG. 52, for example, the external terminals 204 of the semiconductor chip 203 and the inner leads 206 of the lead frame 205 are assembled.
(Inner electrode) for electrical connection.

The schematic configuration of the wire bonding apparatus 201 is as shown in FIG. 43, and an XY stage 208 on which a bonding head 207 as a driving mechanism is mounted, a bonding stage 210 on which a lead frame 205 is mounted, and And a control unit 211 for controlling the operation.

The control unit 211 performs overall control of the wire bonding apparatus 201, and is configured by, for example, a microcomputer system including a microprocessor and a memory, and is a system capable of performing a bonding operation according to operating conditions set by an operator. .

The bonding stage 210 includes a heat block 212 that can move up and down.

The heat block 212 is made of a heat conductive material such as a stainless alloy, and is detachably attached to the bonding stage 210 main body.

Also, a heating source (not shown) such as a cartridge heater is provided inside the heat block 212, and a stage is provided.
It has a function of raising the temperature of the lead frame 205 on the upper surface of the 210 to a predetermined temperature.

In the present embodiment, the bonding stage
As shown in FIG. 44, the lead frame 205 supplied on the 210 is extended around a tab 216 supported at the approximate center thereof by a tab suspension lead 215, and in a non-contact manner with the tab 216 in four directions in a plane. An inner lead 206 is provided as an inner end electrode to be provided. Each inner lead 206 is connected to each other by a frame at a further outer peripheral portion in FIG.

Note that FIG. 44 shows the lead frame 205 in a state where wire bonding has already been completed, but in a state where the semiconductor chip 203 is mounted on the tab 216 in a state where the semiconductor chip 203 is supplied on the upper surface of the stage 210. It is.

Such a lead frame 205 is obtained by processing a plate-like member having a thickness of about 0.15 mm such as Kovar, 42 alloy or nickel alloy into a shape shown in FIG.

As shown in FIG. 45, a part of the front end surface of the inner lead 206 (the inner end electrode) is formed of an uneven surface 206A. Such an uneven surface 206A is formed by first processing the lead frame 205 into the shape shown in FIG.
It can be formed by pressing the tip surface of 06 with an uneven punch. Also, FIG. 7 shows a case where a cut is formed in a part of the tip surface of the inner lead 206 in a pattern. By increasing the density of such irregularities, the distal end surface of the inner lead 206 may be made rough. By the function of the uneven surface 206A, the coating film 217A of the coating wire 217 to be described later
The removal is surely performed, but the details will be described later.

Next, the semiconductor chip 203 mounted on the tab 216 of the lead frame 205 will be described.

The semiconductor chip 203 is connected to the tab 216 as shown in FIG.
It is fixed via a bonding material 218 such as a silver paste, a silicon paste, or a gold foil, which has a thickness of about 30 μm.

Such a semiconductor chip 203 is obtained by slicing an ingot made of silicon (Si) obtained by a technique such as a single crystal pulling method in a crystal direction into a wafer state, and oxidizing the surface of the wafer using a photoresist technique. After being formed through a diffusion process to form a microprocessor or a logic circuit or the like, it can be obtained by dicing into a square shape.

A brief description of the schematic configuration of each layer inside such a semiconductor chip 203 is as follows. A silicon oxide film 221 of about 0.45 μm is formed on an upper layer of a chip substrate 220 made of silicon (Si) having a thickness of about 40 μm. In addition, a PSG film 222 as an interlayer insulating film is further
It is formed with a thickness of about m. A passivation film 223 as a protective film is deposited on the uppermost layer with a thickness of about 1.2 μm, a part of which is opened and has a thickness made of aluminum (Al) partially provided thereunder.
External terminals 4 (bonding pads) of about 0.8 μm have upper surfaces exposed to the upper outside.

On the other hand, as shown in FIG. 43, inside the bonding head 207 on the XY stage 208,
It is arranged to be able to move up and down by a guide shaft 225 provided in a vertical manner with respect to the stage 208, and
A ball screw mechanism 227 that converts the rotation of the servo motor 226 fixed to the bonding head 207 into a vertical linear motion is provided on the side surface of the bonding head 207. Therefore, the vertical movement block 224 can be moved up and down by a predetermined amount with the rotation of the servomotor 226.

The vertical movement block 224 has a bonding arm 230 rotatable in a vertical plane about a rotation shaft 228. One end of the bonding arm 230 has an elasticity such as a spring fixed to the vertical movement block 224. 43 is urged upward by means 232, and is configured so that a counterclockwise urging force acts on the bonding arm 230 with the operation of the vertical movement block 224. When the bonding tool 233 contacts the external terminals 204 of the semiconductor chip 203, the elastic means 232
It is configured to prevent the 204 from being pressurized more than necessary, and to prevent the occurrence of such damage and destruction.

An ultrasonic oscillator 234 is provided at the inner end of the bonding arm 230 on the side of the vertical movement block 224, so that predetermined ultrasonic energy can be supplied to the bonding arm 230. In this embodiment, the ultrasonic oscillator 234
Has a structure in which the output energy is variably controlled based on a control signal of the control unit 211, and the control unit 211 uses an ultrasonic oscillator based on a program stored in the storage unit.
234 is instructed to control the output of the super sweet wave energy.

At the tip of the bonding arm 230 to which the ultrasonic energy is transmitted, a bonding tool 233 (capillary) is provided. The covering wire 217 supplied from the wire spool 235 is inserted into the bonding tool 233 with its tip slightly protruding.

Next, an example of the configuration of the covered wire 217 used in this embodiment will be described.

As shown in FIG. 51, the covering wire 217 used in this embodiment has a cross-sectional structure in which a covering film 217A is attached around a metal wire 217B.

To explain the components of the covered wire 217,
Gold (Au), copper (Cu), or aluminum (Al) is used as the metal wire 217B.

As the coating film 217A, a heat-resistant polyurethane resin is used, which is formed by reacting a polyol component with an isocyanate, and has a molecular skeleton containing a structural unit derived from terephthalate acid. The use of a heat-resistant polyurethane resin having such a composition as the coating film 217A is extremely useful for improving the thermal degradation and bonding property of the coating film 217A, and further improving the peeling strength of bonding.

The specific characteristics of the coating film 217A include, for example, a temperature cycle test or a wear test under the experimental conditions shown in FIG. 52, and the number of times the coating film 217A was destroyed after 100 hours in an environment of 150 to 175 ° C. It is important to select a material that satisfies the condition that the deterioration rate in reduction is within 20% as a constituent material of the coating film 217A.

Furthermore, when the actual wire bonding operation is performed with the covered wire 217, it is necessary that a defect does not occur in the bonding property. According to the research results of the inventor of the present invention, it is desirable that the coating film 217A be made of a material that is non-carbonizable when the coating film 217A is removed by heating when forming the metal balls 217C described later.

The reason is as follows. That is, in the heating and removal of the coating film 217A during the formation of the metal ball 217C described below, the coating film 217A melts above the metal ball 217C, but at this time, the coating film 217A is carbonizable. In
Under the heating temperature, for example, a high temperature condition of about 1060 ° C., the coating film 217A is carbonized without being decomposed. As a result, the carbonized coating film 217A adheres to and remains on the surface of the metal wire 217B so as to wrap the metal wire 217B immediately above the metal ball 217C. It causes clogging and, in the worst case, causes wire curl and even breakage.

Considering such facts comprehensively, it is necessary for the coating film 217A of the coating wire 217 to satisfy at least the following two conditions.

That is, first, through a temperature cycle test or a wear test under the experimental conditions shown in FIG.
The deterioration rate in reducing the number of times of destruction of the coating film 217A after 100 hours under a temperature condition of 75 ° C. should be 20% or less.

Second, the coating film 217A during the formation of the metal balls 217C
It should be composed of a material that is non-carbonizable when it is removed by heating.

The heat-resistant polyurethane as a constituent material of the coating film 217A satisfying the above conditions will be described more specifically.
This heat-resistant polyurethane is obtained by using a polymer component mainly containing a terephthalate acid-based polyol containing active hydrogen and isocyanate. It should be noted that “being a main component” here means that the case where the whole consists only of the main component is included.

Terephthalic acid-based polyol containing the active hydrogen, terephthalic acid and polyhydric alcohol, using OH / COO
In the range of H = 1.2-30, set the reaction temperature to 70 ° C-250 ° C,
It can be obtained by a conventional ester chemical reaction. Generally, the average molecular weight is in the range of 30 to 10,000 and the hydroxyl group is 100 to 500.
The one having a hydroxyl group at both ends of the molecular difference is used.

Raw materials constituting such a terephthalic acid-based polyol include ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol,
Hexane glycol, butane glycol, glycerin,
Aliphatic glycols such as trimethylolpropane, hexanetriol and pentaerythritol;
In addition to the above, polyhydric alcohols such as 1,4-dimethylolbenzene can be used. Among the above, it is particularly preferable to use ethylene glycol, propylene glycol, and glycerin.

Terephthalic acid is used as the dicarboxylic acid. If necessary, amic acid and imidic acid can be used in combination.

Further, to the extent that the heat resistance is not reduced, diphthalic acid, orthophthalic acid, succinic acid, adivisic acid, dibasic acids such as sebacic acid, or 1,2,3,4-butanetetracarboxylic acid, cyclopentanetetracarboxylic acid, Polybasic acids such as ethylenetetracarboxylic acid, pyromellitic acid and trimellitic acid may be used in combination.

As the isocyanate to be reacted with the terephthalic acid-based polyol, the isocyanate group of a polyvalent isocyanate having at least two isocyanate groups in one molecule such as toluylene diisocyanate and xylylene diisocyanate is converted into a compound having active hydrogen, for example, phenol. , Caprolactam and those blocked with methyl ethyl ketone oxime.
Such isocyanates are stabilized. Further, a compound obtained by reacting the above polyvalent isocyanate compound with a polyhydric alcohol such as trimethylolpropane, hexanetriol or butanediol and blocking with a compound having active hydrogen may also be used.

Examples of the isocyanate compound, manufactured by Nippon Polyurethane Co., Millionate MS-50, Coronate 2501,250
3,2505, Coronate AP-St, Death Module CT-St and the like. It is preferable to use a polyisocyanate having a molecular weight of about 300 to 10,000.

In the present invention, a coating composition is prepared by using the above-described raw materials, and the coating composition is applied to the metal wire 217B of the wire main body, and several μm
By forming a coating film with a thickness of
This is to obtain a covered wire 217 insulated around 217B.

As the coating composition, the hydroxyl group 1 of the polyol component is used.
Per equivalent, isocyanate groups of the stabilized isocyanate
0.4 to 4.0 equivalents, preferably 0.9 to 2.0 equivalents and a required amount of a curing accelerator are added, and an appropriate amount of an organic solvent (phenols, glycol ethers, naphtha, etc.) is further added. % By weight. At this time, if necessary, an appropriate amount of an additive such as an appearance improving agent and a dye can be blended.

In the present invention, the isocyanate group of the stabilized isocyanate is 0.4 to 0.4 per hydroxyl equivalent of the polyol component.
The reason for adding 4.0 equivalents is that if it is less than 0.4 equivalent, the crazing characteristics of the resulting insulated wire will decrease, while the wear resistance of the coating film exceeding 4.0 equivalents will deteriorate. The curing acceleration catalyst added at the time of preparing the coating composition is preferably 0.1 to 10 parts by weight per 100 parts by weight of the polyol component. Also, if this is less than 0.1 part by weight, the tendency of curing accelerated curing to be reduced and the ability to form a coating film tends to be poor, and if it exceeds 10 parts by weight, the heat-resistant urethane bonding wire obtained has a heat-deteriorating property. This is because a decrease is observed.

Examples of the curing acceleration catalyst include metal carboxylic acids, amino acids, and phenols.Specifically, naphthenic acid, octenoic acid, zinc salts such as persatic acid, iron salts, copper salts, manganese salts, cobalt salts, A tin salt, 1,8 diazabicyclo (5,4,0) undecene-7,2,4,6, tris (dimethylaminomethyl) phenol is used.

It can be obtained by applying the coating composition as described above on the surface of the metal wire 217B of the wire main body and baking it with a conventional baking coating apparatus.

The coating and baking conditions vary depending on the amounts of the polyol component, the stabilized isocyanate, the polymerization initiator and the curing accelerator, but are usually about 200 to 300 ° C. for about 4 to 100 seconds. In short, the coating composition is baked at a temperature and for a time sufficient to substantially complete the curing reaction, and the coated wire 217 of this embodiment is obtained.

The thickness of the coating film 217A varies slightly depending on the ultrasonic energy and the thermocompression force of the bonding tool 233, but is preferably, for example, about 0.2 to 3 μm. In other words, if the film thickness is small,
This is because the insulation reliability of the 217A is lacking, and if it is large, it is difficult to remove the coating film 217A during bonding.

According to the study results of the present inventors, as a constituent material of the coating film 217A, in addition to the heat-resistant polyurethane having the above-described composition, a commercially available polyurethane, and formal also satisfy the non-carbonizing requirement, Coating film 217 after 100 hours at 175 ° C
Since the rate of deterioration under the above conditions in reducing the number of times of A destruction exceeds 20%, the properties of the coating film 217A are insufficient.

On the other hand, polyimide, polyamide, nylon, polyester, polyamide imide, polyester imide, etc. exhibit carbonization when forming the metal balls 217C or when removing the coating film 217A by heating, so that it is used as the coating film 217A of the coating wire 217. Was found to be insufficient in characteristics.

As shown in FIG. 47, in the wire bonding apparatus 201 of the present embodiment, as shown in FIG. 47, the coated wire 217, the wire spool 235 around which the coated wire 217 is wound, the airbag tensioner 236, 237
Then, it is supplied to the bonding tool 233 via the clamper 238.

The wire spool 235 is formed by, for example, performing alumite treatment on the surface of a cylindrical aluminum metal. This alumite treatment is performed to improve mechanical strength and prevent generation of scratches. However, in order to prevent the covering wire 217 wound therearound from being charged, chrome (Cr) plating or the like may be applied to perform a surface treatment to provide conductivity. Further, the wire spool 235 itself may be made of a stainless alloy.

The wire spool 235 is supported by a spool holder 35A, and a rotation shaft 235B of the spool holder 235A.
Is fixed to the bonding apparatus main body 201A. The spool holder 235A is made of, for example, a grounded stainless alloy so that at least a part thereof has conductivity. Therefore, the spool holder 23
In the covering wire 217 wound around 5A, the covering film 217
The static electricity charged to A is discharged through the stainless alloy part. Although not shown in detail, one end of the winding start portion of the wound covered wire 217 has the coating film 217A removed to expose the metal wire 217B, and the exposed portion of the metal wire 217B is exposed. Wire spool
Joined to 235. Therefore, as shown in FIG. 47, the metal wire 217B of the covered wire 217 in the wound state is connected to the reference potential GND through the wire spool 235, the spool holder 235A, the rotating shaft 235B, and the bonding device main body 201A.
It is connected to the. This reference potential GND has the same value as the reference potential GND of the arc generator 240 in this embodiment. In this manner, by connecting the metal wire 217B of the covering wire 217 to the reference potential GND, a metal ball
At the time of forming C, the potential difference between the electric torch 241 and the metal wire 217B of the covering wire 217 is secured to a specified value, and stable generation of the arc Ac can be realized, so that the metal ball 217C can be reliably formed.

As shown in FIGS. 48 and 49, the airbag tensioner 236 has a pair of guide plates 236A through which the covering wire 217 can pass. This guide plate 236A is made by subjecting the surface of an aluminum alloy to an alumite treatment and further plating the surface with chromium (Cr).
It may be made of a stainless alloy or the like. At least at the time of contact with the insulated wire 217
Any structure can be used as long as it can prevent the charging of 17. The above guide plate
As shown in FIG. 49, a plurality of protrusions 236B are provided on the surface of the wire 236A on the wire passage space α side. This projection 23
6B is provided in order to minimize the contact portion between the covering wire 217 passing through the wire passage space α and the guide plate 236A, and by the action of the projection 236B, the covering wire passing through the wire passage space α. 217 is the above guide plate 2
The contact point is almost in a point contact state with 36A, thereby preventing the coating film 217A from being charged due to contact friction. Therefore, the surface of the protrusion 236B also needs to have conductivity,
The surface is plated with chromium (Cr) or projections 236B
It is itself composed of a stainless alloy or the like. As a technique for obtaining such a structure of the projection 236B, the inner peripheral surface of the guide plate 236A may be projected using a processing technique such as pressing, or the inner peripheral surface of the guide plate 236A formed flat. The rod-shaped member constituting the projection 236B may be fixed by means such as joining or bonding.

A fluid supply pipe is provided at one longitudinal end of both guide plates 236A.
A metal adapter 243 connected to 242 is bonded, and a fluid outlet 244 is opened at an end surface of the adapter 243. A flat spacer 2 from around the fluid outlet 244
45 project in the longitudinal direction, and the spacer 245
Determines the width of the wire passage space α. The width of the wire passage space α determined in this manner varies depending on the diameter of the covering wire 217 used, the height of the protrusion 236B, and the like, but is set to about 1 mm as an example.

The fluid supply pipe 242 connected to the adapter 243 is connected to a fluid supply source. The fluid supply source has, for example, a built-in corona discharge means, whereby ion gas separated by ion is supplied to the wire passage space α from the fluid outlet 244 of the adapter 243 as a current removing member Gs. ing.

Therefore, according to the present embodiment, the airbag tensioner
It is possible to apply the back tension to the covering wire 217, which is the original purpose of the 236, and to remove the static electricity from the covering wire 217 by using the current eliminator Gs. Further, as described above, the contact between the covering wire 217 and the guide plate 236A (the airbag tensioner 236) is substantially in a point contact state by the action of the projection 236B on the inner peripheral surface of the guide plate 236A. Accordingly, the charging of the covering wire 217 is also prevented.

The coated wire 217 supplied from the wire spool 235 and passing through the airbag tensioner 236 is
And, it is inserted into the bonding tool 233 via the clamper 238. The sprocket 237 is for accurately positioning the covering wire 217 with respect to the bonding tool 233, and is fixed to the bonding apparatus main body 201A. The clamper 238 is for holding / opening the covering wire 217 inserted into the bonding tool 233, and has a structure in which the covering wire 217 is clamped from the side by opening and closing movement of the pair of clamper chips 238A.

In the present embodiment, the sprocket 237 and the clamper 238 that are in contact with the coating wire 217 are made of a conductive metal, so that the coating film 217 of the coating wire 217 is formed.
A charging of A and removal of static electricity of the coating film 217A are performed. When a conductive metal cannot be used for reasons such as abrasion resistance as in the case of the clamper 238, an outlet for the current eliminator Gs similar to that described in the airbag tensioner 236 is provided to provide the covering wire 217. In addition, by performing the static elimination blow of the member, it is also possible to realize the prevention of static electricity and the static elimination of the coated wire 217.

When forming the metal ball 217C, the bonding tool 233 located below the clamper 238
As shown in the figure, the structure is covered with a cover 247. The cover 247 is rotatable in the direction of arrow A in the figure, and is configured to insert the bonding tool 233 from the tool insertion port 248 by this rotation and cover it. The reason for providing such a cover 247 is, first, to prevent the semiconductor chip 203 or the inner leads 206 from being contaminated by the scattering of the coating film 217A that melts when the metal balls 217C are formed. Second, the metal wire 217B of the insulated wire 217
This is to make it easier to maintain an antioxidant gas atmosphere (shield gas atmosphere) when using an oxidizing material such as Cu or Al. Such a cover 247 can be made of, for example, a heat-resistant stainless steel alloy. Further, the cover 247 may be formed of a heat-resistant glass material having transparency so that an operator can confirm the formation state of the metal balls 217C inside.

An electric torch 241 (arc electrode) is arranged at the bottom of the cover 247 as shown in FIG. The electric torch 241 is disposed at a position close to the tip of the metal wire 217B of the covering wire 217 led out from the tip of the bonding tool 233 (see FIG. 50), and generates an arc Ac between the two to form a metal ball 217C. It is configured to form. Such an electric torch 241 can be formed of tungsten (W) or the like that can withstand high temperatures.

The electric torch 241 has a hollow interior,
A suction pipe 251 connected to a suction device 250 as shown in FIG.
, And is configured to suck and remove the coating film pieces and the like scattered by the cooling fluid CGs ejected from the fluid spray nozzle 252 described later. The coating film piece sucked through the electric torch 241 and the suction tube 251 is sucked by the external suction device 250 and then discharged to the outside.

The electric torch 241 is electrically connected to the arc generator 240 via the suction tube 251. The suction tube 251 is
For example, the electric torch 241 is made of a conductive metal such as a stainless alloy, and is fixed to the electric torch 241 with an adhesive metal layer such as an Ag-Cu brazing material interposed therebetween. The suction tube 251 further fixes the cover 247 with a sandwiching member 253 interposed therebetween. Therefore, the electric torch 241 and the cover 247 are
It is configured to be able to move together through 1.

As means for moving the suction tube 251, a support member 254 for fixedly supporting the suction tube 251, a crankshaft 255 for rotating the support member 254 in the direction of arrow A in FIG. 47, and rotating the crankshaft 255 A drive source 256 such as an electromagnetic solenoid is used. The rotation of the crankshaft 255 is realized by the movement of a shaft 257 connected to the crankshaft 255 and movable in the direction of arrow B in FIG. The crankshaft 255 is rotatably supported by the bonding apparatus main body 201A.

A fluid spray nozzle 252 is attached to the inside of the cover 247 from the outside of the cover 247 to the inside of the cover 247 of the rotating structure. FIG. 50 shows the cooling fluid C of the fluid spray nozzle 252.
The drawing shows a supply mechanism of Gs. The cover 247 is arranged so that the covering wire 217 protruding from the bonding tool 233 in the cover 247 can supply the cooling fluid CGs to the protruding root portion.

Cooling fluid CGs ejected from the fluid spray nozzle 252
As shown in the figure, the coating film 217A melted by the arc Ac between the electric torch 241 at the time of forming the metal ball 217C at the tip of the coating wire 217 is scattered and removed from the peripheral surface of the coating wire 217. The melted coating film 217A has a function of cooling and hardening the coating film 217A in a fixed amount to suppress the generation of a resin pool, thereby preventing clogging in the bonding tool 233. From such a viewpoint, the fluid spray nozzle 252 is disposed at a position facing the covering wire 217 from an obliquely upper side in the drawing to suppress the melting of the covering film 217A, and the rear end side ( The cooling fluid CGs is sprayed from the upper part) to the tip part (the lower part).

It is desirable that such a fluid spray nozzle 252 be fixed to the cover 247 and not to the bonding tool 233 as in the present embodiment. That is, when such a fluid spray nozzle 252 is fixed to the bonding tool 233, the weight of the bonding tool 233 increases, so that the load of ultrasonic vibration increases and bondability decreases. .

As the cooling fluid CGs, N ₂ , H ₂ , He, Ar, clean air or the like can be used. As shown in FIG. 50, a cooling device 260 is provided by a fluid spraying device 258 (fluid source). ,
The fluid spray nozzle through the flow meter 261 and the fluid transfer pipe 262
252. At this time, the fluid spraying device 2
In 58, a corona discharge means may be provided, and the ion gas (current eliminator Gs) subjected to ion separation may be used as the cooling fluid CGs. In this case, since the charge of the covering wire 217 can be removed immediately before the wire bonding operation, electrostatic breakdown of the semiconductor chip 203 due to the charging of the covering film 217A can be prevented. According to the study of the present inventors, it has been confirmed that the spraying of a gas with a simple N ₂ gas in addition to the above-mentioned ion gas also has an effect of eliminating the charge of the coating film 217A.

The cooling device 260 is configured to actively cool the cooling fluid CGs below normal temperature. The cooling device 260 can be constituted by, for example, an electronic cooling device utilizing the Peltier effect. Although the illustration is simplified in FIG. 50, the periphery of the fluid transfer pipe 262 between the cooling device 260 and the fluid spray nozzle 252 is covered with a heat insulating material 26.
3, so that the temperature rise of the cooling fluid CGs in the fluid transfer pipe 262 is suppressed. Further, the fluid transfer pipe 262 itself may have a double pipe structure of an outer pipe and an inner pipe so that cooling is actively performed even during the transfer of the fluid.

In FIG. 47, an arc generating device 240 indicated by a range surrounded by a two-dot chain line includes a capacitor C1, a storage capacitor C2, an arc generating thyristor D activated by a trigger, and a resistor R. The DC power supply DC supplied to the arc generator 240 has, for example, a negative polarity of about -1000 to -3000 [V].

The DC power supply DC is connected to the electric torch 241 via the thyristor D and the resistor R, and the reference potential GND side is set to, for example, 0 [V]. In the figure, V and A indicate a voltmeter and an ammeter, respectively.

Next, a wire bonding method according to the present embodiment will be described.

When the XY stage 208 is operated while the lead frame 205 is mounted on the bonding stage 210, the bonding head 207 is moved by a predetermined amount, and the bonding tool 233 is positioned directly above the semiconductor chip 203 on the tab 216. State.

In this state, the drive source 256 shown in FIG.
51 moves in the direction of arrow A in FIG.
Is covered by the cover 247.

Next, as shown in FIG.
A high voltage of about 000 to -3000 [V] is applied, and an arc Ac is generated between the electric torch 241 connected thereto and the tip of the metal wire 217B of the covering wire 217 protruding from the bonding tool 233. . By the action of the arc Ac, the tip of the metal wire 217B is melted to form a spherical metal ball 217C. At this time, the coating film 217A of the coating wire 217 melts from the wire tip direction due to the heat of the arc Ac, the coating film 217A in this portion is removed, and the surface of the metal wire 217B is exposed.

It is desirable that the formation of the metal ball 217C be performed in as short a time as possible. At this time, by forming the metal balls 217C with high energy (high current and high voltage), the amount of the coating film 217A of the coating wire 217 that has melted can also be reduced. Performing the formation of the metal ball 217C in a short time and with high energy in this way means stabilizing the state of the generation of the arc Ac.
In the present embodiment, as described above, the electric torch 241 is
Since the metal wire 217B of one of the covering wires 217 is fixed and held at the reference potential GND (= 0 [V]) at a negative potential of about -3000 [V], the arc Ac is also stable. As a result, an increase and variation in the melt-up amount are suppressed.

Further, at the time of forming the metal ball 217C, the cooling fluid CGs is sprayed on the melted portion of the coating film 217A of the coating wire 217 through the fluid spray nozzle 252 to the bonding space surrounded by the cover 247. I have. The sprayed cooling fluid CGs causes the melted coating film 217A to be scattered, sucked by the suction device 250 through the electric torch 241 and the suction pipe 251 and removed to the outside of the system.

The cooling fluid CGs from the fluid spray nozzle 252 is cooled to, for example, about −10 to 0 ° C. by the cooling device 260 shown in FIG. 50, and the cooling fluid CGs from the fluid spray nozzle 252 at this time is at a low temperature. To a certain extent, the amount of the covered wire 217 melted becomes smaller. That is, the cooling fluid CGs cooled by the cooling device 260 can actively cool the metal wire 217B, the coating film 217A and the bonding tool 233 of the coating wire 217, and thus affect the other coating film 217A. The coating film 217A only in the portion where the arc Ac is generated can be melted without giving the effect, and the amount of melting of the coating film 217A can be controlled.

After the metal ball 217C is formed as described above, the drive source 256 is operated again, the suction pipe 251 is rotated, the cover 247 is detached from around the bonding tool 233, and the bonding tool 233 is opened. Becomes

In this state, the servo motor 226 of the bonding head 207
When the ball screw mechanism 227 is moved downward by a predetermined amount, the bonding tool 233
It lands on the upper predetermined external terminal 204.

When the ultrasonic oscillator 234 is operated under the control of the control unit 211 while maintaining the landing state (application of the first ultrasonic vibration), predetermined ultrasonic vibration is applied to the bonding arm 23.
It is transmitted to the bonding tool 233 from 0.

At this time, due to the synergistic effect of the urging force by the operation of the vertical movement block 224, the ultrasonic vibration, and the heating by the heat block 212, the metal ball 217C
(First bonding).

Next, the ultrasonic energy of the ultrasonic oscillator 234 is returned to the initial value by the control of the control unit 211 (see FIG. 42), and when the servo motor 226 is driven, the bonding tool 233 is moved above the semiconductor chip 203. To rise. XY stage 2
When 08 is activated, the bonding tool 233
The path indicated by the two-dot chain line in FIG.
And moves to a position just above a predetermined portion of the inner lead 206. Here, the “predetermined portion” refers to the aforementioned uneven surface 206 on the surface of the inner lead 206.
The part where A is formed is shown.

Note that, when the bonding tool 233 is moved, the ultrasonic energy from the ultrasonic oscillator 234 may be continued.

By continuing the application of the ultrasonic energy, the attraction of the insulated wire 217 in the bonding tool 233 is prevented, and the wire feed from the tip of the bonding tool 233 becomes smooth. Deformation such as bending of the covered wire 217 due to is prevented,
Loop abnormalities are also suppressed.

In this state, when the servo motor 226 operates, the bonding tool 233 removes the uneven surface 20 of the inner lead 206.
Land on 6A. Next, when the ultrasonic oscillator 234 is operated under the control of the control unit 211 (application of the second ultrasonic vibration), the abdomen of the covered wire 217 led out from the tip of the bonding tool 233 is in contact with the above-mentioned uneven surface 206A. The coating film 217A in this portion is slid and mechanically broken and removed, and the metal wire 21
7B is exposed.

When the XY stage 208 is operated and the bonding tool 233 is moved outward (rightward in FIG. 46) on the inner lead 206 while the second ultrasonic vibration is continued,
Under the control of the controller 211, the application state of the ultrasonic energy of the ultrasonic oscillator 234 is switched (third ultrasonic vibration),
This ultrasonic vibration and the inner lead 206 of the XY stage 208
The exposed portion of the metal wire 217B is joined to the surface of the inner lead 206 by a synergistic effect with the heating from the heater 264 provided inside corresponding to the above.

The first (S1), second (S2) and third
FIGS. 42 (a) and 42 (b) show the transition of the ultrasonic energy due to the ultrasonic vibration in (S3). In the figure, the first and third ultrasonic vibrations (S1, S3) are necessary for joining the metal wire 217b to the external terminal 204 or the inner lead 206, and the second ultrasonic vibration (S2) Are necessary for breaking the coating film 217A. According to the study of the present inventors, the ultrasonic energy necessary for the destruction and removal of the coating film 217A is not always at the level of the ultrasonic energy required for the bonding, and the ultrasonic frequency and the like at the time of bonding are not necessarily the same. Low frequency ones have been found to be more effective.

Therefore, in the present embodiment, as shown in the figure, by controlling the ultrasonic oscillator 234 so as to obtain the optimum ultrasonic energy output for the purpose of applying the ultrasonic vibration, the removal of the coating film 217A can be efficiently performed. In addition, the metal wire 217B can be joined to the external terminal 204 and the inner lead 206.
In the figure, the first and third ultrasonic vibrations (S
Although the levels of the ultrasonic energy in (1, S3) are set to be equal, the level of the ultrasonic energy may be changed to a different level according to the temperature condition due to heating or the like.

As described above, in this embodiment, by controlling the ultrasonic energy of the ultrasonic oscillator 234 variably by the control unit 211, it is possible to efficiently remove the coating film 217A and improve the bonding reliability. Has become.

Further, in the present embodiment, furthermore, on the inner lead 206, the portion where the coating film 217A is removed and the portion where the bonding is performed are different portions, so that the bonding portion is kept clean and the coating film 217A Bonding failure due to contamination such as is prevented.

Further, when the coating film 217A is removed, since the surface of the inner lead 206 is formed of the uneven surface 206A, the remaining of the coating film 217A can be reliably prevented, and the metal wire 21
The joining strength between 7B and inner lead 206 can be increased.

After the completion of the wire bonding process as described above, the lead frame 205 is placed in a mold, and a molten resin such as an epoxy resin is injected into the mold at a high pressure, so that the resin sealing shown in FIG. 52 is performed. The package body 265 of the semiconductor device 2 is formed. At this time, particularly in the second bonding, the bonding between the metal wire 217B and the inner lead 206 is performed in a state where the coating film 217A is incompletely peeled and the coating film 217A remains on the surface of the inner lead 206. In this case, there is a possibility that the flow of the wire or the breaking of the covering wire 217 may be caused by the injection pressure of the molten resin. In this regard, in this embodiment, the control of the application of the ultrasonic vibration and the uneven surface 206 on the surface of the inner lead 206 are performed as described above.
Since the coating film 217A is almost completely peeled off by destruction and removal of the coating film 217A by sliding contact with A, the bonding between the exposed metal wire 217B and the inner lead 206 is reliably performed, The wire flow and the breakage of the covering wire 217 are effectively prevented.

After the molten resin injected in this way is cured,
The lead frame 205 on which the package body 265 is formed is taken out of the mold.

Next, the resin-encapsulated semiconductor device 202 shown in FIG. 52 is obtained by processing and molding the leads 266 (outer leads) protruding from the side surface of the package body 265. In this semiconductor device 202, the package body 2
A thin package structure with a thickness of about 1 mm has been realized.

As described above, in the present embodiment, in particular, since the coating film 217A can be reliably broken and removed in the second bonding, the bonding strength is increased, and the electrode connection in the semiconductor device 202 by the coating wire 217 is increased. Reliability can be improved.

For this reason, for example, in FIG. 44, so-called cross bonding as shown by a, or complicated wiring that straddles the tab suspension lead 215 as shown by b becomes possible, and the integration and height of the semiconductor device 202 are increased. It is easy to respond to functionalization.

Although the invention made by the inventor has been specifically described based on the embodiments, the present invention is not limited to the above-described embodiments, and various changes can be made without departing from the gist of the invention. Nor.

For example, although a case is shown in which a capillary is used as the bonding tool 233, the present invention is not limited to this, and a knife-shaped wedge may be used.

Further, in the embodiment, the case where the ultrasonic vibration applied to the bonding tool 233 is performed intermittently has been described. However, the application of the ultrasonic vibration may be performed continuously from the first bonding to the second bonding. . In this case, the action of the ultrasonic vibration can remove the adsorbed foreign matter around the covering wire 217 in the bonding tool 233 and prevent the curling of the covering wire 217, thereby further improving the bonding reliability in wire bonding. it can.

The following is a brief description of an effect obtained by the representative one of the inventions disclosed in the present embodiment.

That is, by variably controlling the ultrasonic vibration,
In removal and destruction of the coating film and bonding with the electrode surface,
The optimum ultrasonic energy or ultrasonic vibration application conditions such as ultrasonic frequency can be selected, and the coating film can be reliably removed, so that the bonding strength between the metal wire and the electrode surface is improved, Bonding reliability can be improved.

Also, by forming an uneven surface in the vicinity of the electrode, the efficiency of destruction / removal of the coating film by application of ultrasonic vibration can be increased, thereby improving bonding workability and removing the coating film. Is more reliable, and the bonding reliability can be improved.

Further, by forming a part of the electrode surface of the inner end electrode with an uneven surface, the coating film can be surely removed, so that the bonding strength is increased and the semiconductor device structure using the coating wire is substantially reduced. And a highly reliable, highly integrated and highly functional semiconductor device can be provided.

(3) Embodiment 3 This embodiment describes the details of some of the steps of each of the above-described embodiments or a bonding process that is a modification thereof.

FIG. 54 is a schematic partial sectional view showing a main part of the coated wire bonding apparatus of the present invention. In the figure, 301 is a ball having a diameter of about 70 to 90 μm formed by a separated arc discharge, 302 is a coating removal portion (20 to 200 μm) in which the resin coating has melted by heat during ball formation, and 303 is a ball forming atmosphere. A supply gas nozzle, 304 is a discharge electrode integrated therewith, 305a is a core material of a bonding wire, that is, a metal core portion, 305b is a coating layer thereof, and 306 is a thermosonic ball bonding (ball Wedge
Type) capillary (bonding tool)
In addition to applying pressure in the vertical direction, ultrasonic vibration can be applied in the horizontal direction (the extending direction of the bonding arm). 307a and 307b are melt-up preventing gas nozzles, 308 is a multiple lead frame, and 309a to f are die pads on the die pad on the lead frame, respectively.
Bonded integrated circuit chip (309a has wire bonding completed), 310 is a heat block for heating the leads and the chip, 311 is a double-sided open tube through which the lead frame is passed, 312
Is an opening for wire bonding provided on the upper side thereof, 321 is a gas flow for preventing melt-up, 322 is a ball forming atmosphere gas for shielding the ball portion at the time of ball formation and subsequent annealing, and 323a to d are lead frames. 324 is a lead gas atmosphere flow for preventing oxidation, etc., and 324 is a lead frame transfer direction.

Tables 3 and 4 show various conditions at the time of bonding in FIG.

The specific process of wire bonding is as follows.
Explanation will be made based on the figures, Table 3 and Table 4.

First, with the end of the wire on the spool side grounded, a pulse voltage is applied so that the wire side becomes a positive electrode while the distance between the tip of the wire and the discharge electrode 304 is kept constant. An arc discharge is generated between the electrode and the electrode 304, and the heat forms the ball 301 and melts the coating at the tip. At this time, a ball atmosphere gas 322 is blown from the side of the wire before and after formation of the ball to prevent oxidation of the ball. On the other hand, at the same time, in order to prevent excessive melting of the coating, a cooling gas 321 is supplied from above to the wire neck portion immediately above the ball during ball formation and until the melting of the coating stops.

The ball, which has been cooled to about 300 to 200 ° C. in the ball forming gas 322 from the ball temperature (1000 ° C. or higher) at the time of discharge, is subjected to wire bonding. When ball formation is completed, the electrode
304 retracts, the capillary 306 descends, enters the tube 311 through the opening 312 of the tube 311 and performs the first bonding (on the chip 309b by thermosonic bonding).
Then, the capillary 306 moves while sending out the wire 305 to the second bonding point of the corresponding lead. At that point, wedge bonding is performed while breaking the coating. During this time, the inside of the tube is filled with a lead atmosphere gas. The above-described bonding cycle of one wire is performed for about 0.1 to 0.3 seconds.
By repeating the above cycle, bonding of all the wires is performed.

(4) Fourth Embodiment This embodiment shows details or modifications of a part of the structure or steps of the preceding embodiment.

FIG. 55 is a partial sectional view of the surface mount resin package of the present invention. In the figure, 402a is a Si substrate (200 to 400μ).
m), 402b is a final passivation film (1 μm thick) made of SiO ₂ , 402c is an Al bonding pad (1 μm thick; 100 μm × 100 μm square), 402d and e are interlayer insulating films made of PSG or the like (0.5 to 1.5) μm thickness), 402f is LOCOS
Field SiO ₂ film (0.3-1 μm thick) by oxidation (selective oxidation by SiN), 403a-c are lead frames patterned from one metal sheet, 403a is a die pad part, 403b is an inner lead Part, 40
3c is an outer lead part. 404 is an adhesive for die bonding such as Ag paste, 405a is a bonding wire core material, 405b is its coating, 406 is the low stress resin material shown in the previous embodiment, 407 is a spot plating portion at the inner end of the lead, Four
08 is a chamfer at the tip end.

Table 5 is a list showing materials of respective parts of specific examples of these resin-sealed devices, and the examples correspond to Tables 3 and 4.

(5) Embodiment 5 FIG. 56 (a) is an explanatory view showing the arrangement of the heat block, the holding plate, the lead frame, etc. in the wire bonding step which is Embodiment 5 of the present invention, and FIG. 56 (b). ) Is an enlarged explanatory view showing the surface state of the diamond electrodeposition layer, FIG.
The figure is an explanatory view comparing the effect of the present embodiment with the prior art, and FIG.
FIG. 1 is a cross-sectional view illustrating a semiconductor device obtained according to this embodiment.
Fig. 59 is a sectional view showing the state of wire bonding,
FIG. 6 is an explanatory view showing a comparison of the results of a thermal cycle test of a semiconductor device obtained by the conventional method and the method of the present embodiment.

The characteristics of the bonding stage 501 in the wire bonding apparatus of this embodiment are as shown in FIG. 56 (a), and the upper surface of the bonding stage 501 is constituted by a heat block 502. A bank portion 503 and a position fixing groove 504 are formed. The bank portion 503 is provided to fix the position of the tab 505 and to position the wire loop at a fixed height.

The position fixing groove 504 is formed slightly outside the tip of the inner lead 506, and the edge 5 of the position fixing groove 504 is formed.
Inner lead 50 by 04a and holding plate 507 from above
By sandwiching 6, the parallelism between the inner lead surface 506a and the bonding stage surface 501a is ensured.

On the surfaces of the heat block 502 and the holding plate 507, a diamond electrodeposition layer 508 is formed. The surface condition of such a diamond electrodeposition layer 508 is as shown in FIG. 56 (b). The diamond electrodeposition layer 508 is formed by first preparing a diamond fine particle 510 (preferably as sharp as possible) having a diameter of 15 to 20 μm coated with nickel (Ni). 510 is adsorbed on the surface of a stainless steel substrate to be a bonding stage 501 (heat block 502) by electrophoresis.

Next, the stainless steel substrate is heated with the diamond fine particles 510 attached thereto to melt the Ni and fix the diamond fine particles 510 to the surface of the stainless steel substrate.

Note that the diameter of the diamond fine particles 510 may be outside the above range, but if the diameter is too large, the inner lead 506 in a fixed state may be inclined due to variation in the diameter. There is a possibility that the coefficient may decrease and the inner lead 506 may not be securely fixed.

In addition to forming the electrodeposited diamond layer 508, the surface of the bonding stage 501 (heat block 502) may be roughened by directly flawing it. A sufficient fixing effect was not obtained.

The lead frame 511 supplied to the bonding stage surface 501a has a tab 505 at the center, and an inner lead 506 extending from the frame around the tab 505 extends in a non-contact state with the tab 505. Have been.

Such a lead frame 511 has a thickness of, for example, Kovar, 42 alloy or nickel alloy.
It is obtained by subjecting a plate member of about 0.15 mm to press working or etching.

On the tab 505, as shown in FIG. 59, a thickness of 30 μm
The semiconductor chip 513 is fixed via a bonding material 512 such as a silver paste, a silicon paste, or a gold foil, which is applied to a certain degree.

The upper layer of this semiconductor chip 513 is a microprocessor, through an oxidation and diffusion process using photoresist technology,
Alternatively, a logic circuit, a storage circuit, and the like are formed. Briefly describing the schematic configuration of each layer inside the semiconductor chip 513, a silicon oxide film 515 of about 0.45 μm is formed on an upper layer of a chip substrate 514 made of silicon (Si) having a thickness of about 400 μm. On the upper layer, a PSG film 516 as an interlayer insulating film is formed with a thickness of about 0.3 μm. On the uppermost layer, a passivation film 517 as a protective film is deposited with a thickness of about 1.2 μm, a part of which is opened and has a thickness of 0.8 μm made of aluminum (Al) partially provided in the lower layer. Extent of bonding pad 518 is exposed.

Next, a wire bonding step on the bonding stage 501 will be described.

First, when the lead frame 511 on which the semiconductor chip 513 is mounted is supplied onto the stage surface 501a of the bonding stage 501, the bonding tool 520 is positioned directly above a predetermined bonding pad 518.

Next, an arc discharge is generated between the tip of the coated wire 521 (metal wire 522) projected from the bonding tool 520 by the discharge torch, and the tip of the metal wire 522 is heated and melted to form a spherical bonding ball 523. Is done. With the heating, the coating film 5 near the tip of the coating wire 521
The resin 24 gradually melts above the covering wire 521, and the metal wire 522 around the bonding ball 523 is exposed.

Next, the bonding tool 520 is
When descending with respect to 18, the bonding ball 523 protruding from the bonding tool 520 lands on the surface of a predetermined bonding pad 518.

Subsequently, a predetermined load is applied to the tip of the bonding tool 520, and ultrasonic vibration of a predetermined frequency is applied to the tip of the bonding tool 520.

By the synergistic effect of the ultrasonic oscillation power, the heating and the load, the bonding ball 523 is bonded to the surface of the bonding pad 518, and the first bonding is completed.

Subsequently, by moving the bonding tool 520 upward and in the horizontal direction, the middle part of the covered wire 521 is stretched so as to draw a loop while being led out from the tip of the bonding tool 520, and is moved directly above a predetermined inner lead 506. I do.

Next, the tip of the bonding tool 520 is
Is landed at a predetermined position of the inner lead 506 in a state in which. Here, again the bonding tool 52
When ultrasonic vibration is applied to the inner lead 506, the abdomen of the covering wire 521 led out from the tip of the bonding tool 520 is rubbed against the surface of the inner lead 506, thereby covering the contact portion with the inner lead 506. Wire 521
Is peeled off.

After the coating film 524 is peeled off, the application of the ultrasonic vibration is continued, so that the exposed axis (metal wire 522) is bonded to the surface of the inner lead 506. At this time, a heating source such as a heater may be built in the bonding stage 501 together with the application of the ultrasonic vibration to heat the second bonding portion. Further, the ultrasonic vibration may be continuously performed after the completion of the first bonding until the bonding tool 520 moves to the position of the second bonding. By continuing the application of the ultrasonic vibration during the movement of the bonding tool 520 in this way, the bending of the covering wire 521 in the bonding tool 520 can be prevented, so that the clogging can be prevented.

In the present embodiment, when the ultrasonic vibration is applied in the second bonding, as described above, the inner lead 506 is attached to the diamond electrodeposition layer 508 formed on the surface of the holding plate 507 and the holding piece, respectively. It is securely fixed by. Therefore, resonance of the inner leads 506 can be prevented, and the coating film 524 can be reliably peeled.

In this embodiment, the edge 504 of the position fixing groove 504 is further provided.
Since the surface of the inner lead 506 is fixed so as to be kept parallel to the surface of the bonding stage 501 by the a and the holding plate 507, bonding failure due to the inclination of the inner lead 506 and the like is also prevented.

After the bonding of the covering wire 521 is completed as described above, the covering wire 5 is positioned above the bonding tool 520.
When the bonding tool 520 is lifted in the Z direction by a predetermined amount,
Unnecessary portions of the covering wire 521 are cut off from the above-mentioned bonding portions, and the second bonding is completed.

The electrical connection between the semiconductor chip 513 and the inner leads 506 is realized by repeating the bonding cycle described above a predetermined number of times for all the bonding pads 518 and the inner leads 506.

After the above wire bonding step, the lead frame 51
1 is installed in a mold, and a synthetic resin in a molten state is injected at a high pressure into the mold to form a package body 526 of the semiconductor device 525.

Next, specific effects obtained by the present embodiment will be described based on experimental results of the inventor.

FIG. 57 (a) shows a comparison between this embodiment and the prior art. The inventor of the present invention has performed the second bonding using three types of bonding stages: a bonding stage having a conventional structure, a bonding stage having a position fixing groove 504, and a bonding stage 501 having a position fixing groove 504 and a diamond electrodeposition layer 508. The relationship between the peeling and cutting rates of the coated wire 521 on the side and the ultrasonic oscillation power was inspected.

FIG. 57 (b) shows the relationship between the crushing width of the wire on the second bonding side and the ultrasonic oscillation power, and FIG. 57 (c) shows the relationship between the tensile strength of the wire and the ultrasonic oscillation power. is there.

As is clear from FIG. 57 (b), when the ultrasonic oscillation power is increased, the crushed width of the wire on the second bonding side is increased and the thickness of the wire is reduced. ), The tensile strength decreases.
In addition, the cutting of the second bonding portion at the time of wire bonding is also likely to occur.

Therefore, it is desirable to set the ultrasonic oscillation power as small as possible to reduce the crush width of the wire on the second bonding side. However, when the ultrasonic oscillation power is extremely reduced, it is shown in FIG. 56 (a). As coating film 52
On the contrary, since the destructive force of No. 4 decreases and the peeling rate after bonding increases, it is necessary to set the ultrasonic oscillation power to a limit value at which peeling does not occur or a slightly higher value.

In this regard, in the bonding stage structure () of the prior art, the ultrasonic oscillation power does not effectively work for removing the coating film 524 due to the resonance of the inner lead 506. Could not be prevented. For this reason, the bonding workable area is as narrow as 90 bits to 120 bits, which is the value immediately before cutting occurs, and in this area, the tensile strength is also low as shown in FIG.

On the other hand, the position fixing groove 50
In the structure (4) provided with (4), the fixed state of the inner lead 506 is relatively stable, as shown by the characteristic curve shown in FIG.
It has become possible to reduce it to 80 bits.

Furthermore, in the structure () of the bonding stage 501 provided with the diamond electrodeposition layer 508 together with the position fixing groove 504, the fixing of the inner lead 506 is further stabilized, and the ultrasonic oscillation power can be reduced to 60 bits. Was.

As described above, in this embodiment, the fixing of the inner lead 506 can be stabilized by first providing the structure () in which the position fixing groove 504 is provided, and the fixing is further performed by providing the diamond electrodeposition layer 508. Be stabilized. As a result, the working area for wire bonding is 60 to
Since it is expanded to 120 bits, stable wire bonding is realized and a semiconductor device with high bonding reliability can be supplied.

FIG. 58 shows a semiconductor device 525 obtained through this embodiment.
FIG. 4 is a sectional view showing a completed state of FIG. In the figure, the semiconductor chip 513 and the lead frame 511 connected in the above wire bonding step are sealed with epoxy resin by a resin molding method. In the resin molding process, a high-pressure injection of the epoxy resin in a molten state into the mold may cause a flow or disconnection of the covering wire 521, but according to the present embodiment, the bonding strength is high as described above. Since the wire bonding is performed, such a wire flow, a disconnection, and the like do not occur.

Further, since wire bonding using the covering wire 521 is realized, even if contact between the wires occurs, the covering film 524 covering the metal wire 522 comes into contact with each other, so that an electrical short circuit is prevented.

FIG. 59 shows the semiconductor device 525 obtained as described above.
FIG. 4 is an explanatory diagram showing the results of a heat cycle test, and the test conditions are as shown in FIG.

According to the figure, when wire bonding is performed by a conventional bonding stage structure without using the diamond electrodeposition layer 508, a disconnection phenomenon occurs on the second bonding side after 500 cycles or more. This is because, in the prior art, the crushing width in the second bonding is too large, so that the bonding strength gradually decreases due to the repetition of the thermal cycle, and eventually the wire breaks due to thermal stress.

On the other hand, according to the structure of the bonding stage 501 of the present embodiment provided with the diamond electrodeposition layer 508, no disconnection occurred even after completing 1000 cycles.

Although the invention made by the inventor has been specifically described based on the embodiments, the present invention is not limited to the above-described embodiments, and various changes can be made without departing from the gist of the invention. Nor. For example, as a method of forming a rough surface, a case has been described where diamond fine particles are adhered to a contact surface by electrophoresis. However, not only diamond fine particles but also hard granular materials may be used.

Regarding the method for applying diamond fine particles, in addition to the electrophoresis described in the embodiment, for example, an adhesive tape in which diamond fine particles are adsorbed may be attached to the stage surface.

In the above description, the case where the invention made by the present inventor is applied to a wire bonding technique using a so-called covered wire, which is a field of application, has been mainly described. However, the present invention is not limited to this. The present invention is also applicable to a wire bonding technique using a metal wire. In the case of a bare wire, although there is no request to peel off the coating film at the time of the second bonding, the necessity of preventing resonance of the inner lead and increasing the bonding strength is high, and the application of the present invention is extremely effective. .

The following is a brief description of an effect obtained by the representative one of the inventions disclosed in the present embodiment.

According to the present invention, since the inner lead is fixed by the roughened contact surface (for example, the bonding stage surface), resonance of the inner lead due to application of ultrasonic vibration from the bonding tool is prevented. 2 The removal of the coating film of the coating wire in the bonding is reliably performed.

Therefore, bonding reliability in wire bonding using the covered wire can be significantly improved.

According to the present invention, when performing ball wedge bonding using a thin wire bonding wire having a coating of a thin film insulating layer in advance, the ball bonding is performed at the first bonding point, and then the capillary is sent out to the second bonding point. As they move,
By applying the ultrasonic vibration to the capillary, the wire can be smoothly drawn out.

[Brief description of the drawings]

1 (a) and 1 (b) are explanatory sectional views showing a wire bonding procedure according to I of Embodiment 1 of the present invention, FIG. 2 is a schematic configuration diagram of a wire bonding apparatus used in the above embodiment, FIG. FIG. 5 is a half sectional view of a resin-encapsulated semiconductor device obtained by the above embodiment, FIG. 4 is a perspective view of a main part of a wire bonding apparatus used in the above embodiment, and FIG. FIG. 6 is a plan view seen from the direction of arrow VI in FIG. 5, FIG. 7 is a cross-sectional view taken along the line VII-VII in FIG. 6, and FIG. FIG. 9 is a schematic configuration view showing the principle of forming a metal ball in I. FIG. 9 is an exploded perspective view of a main part of a wire spool of the wire bonding apparatus in I in Embodiment 1; FIG. Fig. 11, Fig. 11 shows the wire of I of Embodiment 1 FIG. 12 is a schematic plan view of a local heating unit for bonding, FIG. 12 is a plan view showing an example of the wire bonding of I of Embodiment 1 and FIG. 13 is a chip touch state of the coated wire of I of Embodiment 1; FIG. 14 is an enlarged partial cross-sectional view showing the chip short state, FIG. 15 is a partial cross-sectional view showing the tab touch state of the coated wire, FIG. 16 is an enlarged partial cross-sectional view showing the tab short state, FIG. 17 is a graph showing the short-circuit rate between the semiconductor chip and the coated wire with respect to the temperature cycle in Example 1, I. FIG. 18 is also the short-circuit rate between the tub and the coated wire with respect to the temperature cycle in Example 1, I. FIG. 19 is a model diagram showing experimental conditions used for evaluating the coating film of the coated wire used in I of Example 1 of the present invention, and FIGS. 20 and 21 are diagrams of Example 1 of the present invention. Coating film in I FIG. 22 is an explanatory diagram showing the results of a comparative experiment of wear strength. FIG. 22 is an explanatory diagram showing the experimental results on the relationship between the temperature change and the deterioration rate of the coated wire in the description of I of Example 1. FIG. In Example 1, I, the relationship between the imidization rate of the coating film (horizontal axis), the degradation rate, that is, the degradation rate (vertical axis on the left), and the peel strength of the coated wire for the second bonding (vertical axis on the right) Explanatory drawing showing the experimental results, Fig. 24 is an explanatory drawing showing the experimental results on the temperature cycle amplitude and temperature cycle life of the coated wire, and Fig. 25 is degradation due to the presence or absence of the coloring agent in the coating film of the coated wire. FIGS. 26 to 31 are partial cross-sectional views for explaining a wire bonding state showing a modification of the first embodiment I, and FIG. 32 is an embodiment.・ For 1 II wire bonding equipment FIG. 33 is an explanatory view showing a path of a covering wire from a wire spool to a bonding tool. FIG. 33 is a perspective view showing a structure of an airbag tensioner in II of Embodiment 1 with a part cut away. Is a side view showing the inner peripheral shape of the II airbag tensioner of the embodiment 1; FIG. 35 is a schematic sectional view showing the clamper of the II of the embodiment 1; and FIG. 36 is an enlarged perspective view showing the vicinity of the clamper. FIG. 37 is a schematic plan view showing a driving mechanism of the clamper in the same manner. FIG. 38 is a schematic sectional view of a conventional clamper for comparison with FIG. 35, and FIG. FIG. 40 is an explanatory sectional view showing a wire bonding state, FIG. 40 is a plan explanatory view showing a lead frame showing a wire bonding state according to Example 1 II, and FIG. 41 is a resin sealing type obtained by Example 1 II Semiconduct It is an overall cross sectional view of the apparatus. FIG. 42 is an explanatory view showing an applied state of ultrasonic energy to a bonding tool in an assembling process of a semiconductor device which is Embodiment 2 of the present invention. FIG. 43 is an overall schematic view of a wire bonding apparatus. FIG. 45 is a plan view showing a lead frame used in Embodiment 2 of the present invention. FIG. 45 is an enlarged partial perspective view showing a surface state of an inner lead in Embodiment 2 of the present invention. FIG. 46 is an explanatory sectional view showing a structure of a semiconductor chip. 47 is a perspective view showing a wire supply system, FIG. 48 is an enlarged perspective view showing a main part of the airbag tensioner in the second embodiment, FIG. 49 is a front view of the airbag tensioner, FIG. Is an explanatory view showing an arrangement state of each mechanism in the vicinity of the bonding tool. FIG. 51 is a cross-sectional perspective view showing a structure of the covering wire. FIG. 52 is an explanatory view of a wear test. FIG. 53 shows an entire configuration of the semiconductor device. Interruption It is a diagram. FIG. 54 is a schematic sectional view of a bonding apparatus according to Example 3 of the present invention. FIG. 55 is a sectional view of a resin-sealed semiconductor integrated circuit device according to Embodiment 4 of the present invention. FIG. 56 (a) is an explanatory view showing an arrangement state of a heat block, a holding plate, a lead frame and the like in a wire bonding step which is Embodiment 5 of the present invention, and FIG. 56 (b) is a view showing a diamond electrodeposition layer. FIGS. 57 (a) to 57 (c) are explanatory diagrams comparing the effect of the present embodiment with the conventional technology, FIG. 58 is a cross-sectional view showing a semiconductor device obtained by the present embodiment, FIG. 59 is a cross-sectional view showing a state of wire bonding. DESCRIPTION OF SYMBOLS 1: Resin-sealed semiconductor device, 2: Semiconductor chip, 2A: Substrate, 2A1: Chip substrate, silicon oxide film 2A2, 2A3 ... PSG
Model, 2B: passivation model, 2C: external terminal (bonding pad), 3: lead, 3A: tab, 3B: inner lead, 4: bonding material, 5: coated wire, 5A: metal wire, 5A1
… Metal ball, 5A11, 5A12… 1st bonding part, 5A2, 5A
22: 2nd bonding part, 5B, 5Ba: coating film, 5C: second coating film, 5D: adsorbed foreign matter, 6: resin material, 10: bonding apparatus body, 11: wire spool, 11A: connection terminal, 11Aa
... Insulator, 11Ab ... Conductor, 11Ac ... Connection metal part, 12 ... Bonding part, 13 ... Tensioner, 14 ... Sprocket, 15
... clamper, 16 ... bonding tool (capillary),
16A: bonding arm, 16B: through hole, 16C: conductive material, 17: bonding stage, 18A: covering member, 18B
... Tool insertion port, 18C ... Cooling fluid spray nozzle, 18D ... Electric torch (arc electrode), 18E ... Suction tube, 18F ... Nipping member,
18G: Supporting member, 18H: Insulating member, 18I: Crankshaft, 18J
... Shaft, 18K ... Drive source, 19 ... Suction device, 20 ... Arc generator, 21 ... Spool holder, 21A ... Rotating shaft, 22 ... Bonding head (digital bonding head), 22
A: Guide member, 22B: Vertical movement block, 22C: Female screw member, 22D: Male screw member, 22E: Motor, 22F: Rotating shaft, 22G
… Elastic member, 22H… ultrasonic oscillation mechanism, 23… XY table, 2
4… Base, 25… Cooling fluid spraying device (fluid source), 25A… Cooling device, 25B… Flow meter, 25C… Fluid conveying pipe, 25D… Insulation material, 2
5E: Corona discharge means, 26: heater, 26A: power supply line, 31 ...
Airbag tensioner, 31A: Guide plate, 31B: Projection, 31
C: Fluid supply pipe, 31D: Adapter, 31E: Fluid outlet, 31F
... spacer, 31G ... wire passage space, 31H ... fluid supply source,
31H1: Corona discharge means, 32: clamper, 32A1, 32A2: clamper arm, 32B: shaft support, 32C: cam mechanism, 32D: spring, 32E1: first clamper chip, 32E2: second clamper chip, 32F: blowing Outlet, 32G… Sub arm, 32H… Screw, 32J… Stopper, 33… Resin-sealed semiconductor device, 33A…
Lead frame, 33B… Inner lead, 33C… Tab hanging lead, 33D… Tab, 33E… Package body, 33G… Outer lead, C1… Capacitor, C2… Storage capacitor,
D: thyristor for arc generation, R: resistance, DC: DC power supply, GND: reference potential, Gs: cooling fluid, Gs2: current eliminator, V
... voltmeter, A ... ammeter.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification number Agency reference number FI Technical indication location H01L 21/607 H01L 21/607 B (72) Inventor Susumu Okikawa 5 Josuihonmachi, Kodaira-shi, Tokyo No. 20-1 in the Musashi Factory of Hitachi, Ltd. (72) Inventor Hiroshi Mikino 5-2-1, Kamisumi Honcho, Kodaira-shi, Tokyo In the Musashi Factory of Hitachi, Ltd. (72) Inventor Hiroshi Watanabe Kodaira, Tokyo 5-2-1, Josuizu-cho, Ichizu-shi Musashi Plant, Hitachi, Ltd. (72) Inventor Toshihiro Sato 3-3-2, Fujibashi, Ome-shi, Tokyo Inside Hitachi Tokyo Electronics Co., Ltd. (72) Michio Tanimoto Kodaira, Tokyo Hitachi, Ltd. Musashi Plant, 5-2-1, Josui-Honcho, City (72) Inventor Atsushi Onodera 3-3-2, Fujibashi, Ome-shi, Tokyo Hitachi East Electronics Co., Ltd. (56) References JP-A-63-78544 (JP, A) JP-A-1-321645 (JP, A) JP-A-57-162438 (JP, A) JP-A-61-101043 (JP) JP-A-62-140428 (JP, A) JP-A-2-112249 (JP, A) JP-A-1-295431 (JP, A) JP-A-2-277251 (JP, A)

Claims (4)

(57) [Claims] 1. A method according to claim 1, wherein one portion of said metal wire exposed from one end of a coating wire having an insulating resin coating film applied around a conductive metal wire is connected to an electrode of a semiconductor chip. A method of manufacturing a semiconductor device, comprising a step of connecting another portion of the metal wire, which is selectively exposed at another portion of the wire, to a lead, wherein one of the metal wires exposed from one end of the covering wire is provided. A step of applying ultrasonic vibration with low energy to the bonding tool when moving a portion toward the electrode; and applying ultrasonic vibration with high energy larger than the low energy to the bonding tool to form the metal. A first bonding step of connecting one part of a wire to the electrode; and the bonding tool while the ultrasonic vibration of the low energy is continued in the bonding tool. Sending out the coated wire from the tip of a bonding tool and forming the coated wire in a loop shape; and applying the ultrasonic vibration by the high energy to the bonding tool and exposing another portion of the metal wire to the lead. A method of manufacturing a semiconductor device, comprising: a second bonding step of connecting. 2. The method for manufacturing a semiconductor device according to claim 1, wherein ultrasonic vibrations at an intermediate energy between said low energy and said high energy are applied to said coating film at said other portion of said coating wire. A method of manufacturing a semiconductor device, wherein a portion of the coating film is removed by applying ultrasonic waves by applying ultrasonic waves. 3. A semiconductor device in which a first portion formed on a semiconductor chip and a second portion on an inner lead of a lead frame are connected by a covering wire having an insulator attached around a metal wire. A step of disposing the lead frame on a bonding stage having a rough contact surface; and a step of fixing the inner lead between a pressing member and the bonding stage. A method of manufacturing a semiconductor device, comprising: when joining the covered wire to the second portion, holding the inner lead on the rough contact surface. 4. The method of manufacturing a semiconductor device according to claim 3, wherein said rough contact surface is formed by applying diamond particles to said bonding stage. Method.