JP3319741B2 - Semiconductor device package and sealing material for mounting the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of mounting a semiconductor device on a substrate by a flip chip mounting method via a conductive adhesive, and mechanically connecting the substrate and the semiconductor device via a resin sealing layer. The present invention relates to a semiconductor device mounted body and a mounting method thereof.

[0002]

2. Description of the Related Art Conventionally, soldering has been generally used for connecting connection terminals of electronic components such as semiconductor devices and terminal electrodes of a circuit pattern on a substrate. However, recently, in addition to the miniaturization of semiconductor packages and the like, the number of connection terminals has been increased, and the space between the connection terminals has been narrowed. For this reason, it has become impossible to cope with the conventional soldering in which the area of the bonding portion is large.

In recent years, attempts have been made to increase the efficiency of the mounting area by directly attaching (flip chip mounting) the terminal elements on the substrate with the active element surface of the chip facing downward. Numerous proposals have been made and implemented for this flip-chip mounting method, and representative examples are described below. (1) Low melting point metal bonding such as solder As shown in FIG. 8, a solder bump electrode 8 is provided on an electrode pad 2 of a semiconductor device 1, and a terminal electrode 5 on a substrate 6 is provided.
After the alignment, the solder is melted and the semiconductor device 1
And the substrate 6 are electrically connected. As a method similar to this, as shown in FIG. 9, a gold bump electrode 3 is formed, and a low melting point metal plating layer, for example, an indium plating layer 9 is provided between the bump electrode 3 and the terminal electrode 5 on the substrate 6. A method is also proposed in which the semiconductor device 1 and the substrate 6 are mechanically joined via a sealing layer 10 after the low melting point metal of the indium plating layer 9 is melted and electrically connected. . (2) Bonding by Hardening Shrinkage Stress of Sealing Resin As shown in FIG.
After filling the gap between the semiconductor device 1 and the substrate 6 with a sealing material while the bump electrode 3 on the semiconductor device 1 is aligned with the terminal electrode 5 on the substrate 6, The sealing material is cured to form the sealing layer 12, and the bump electrode 3 and the terminal electrode 5 are formed by the curing shrinkage force of the sealing layer 12.
A compressive stress is generated between the semiconductor device 1 and the semiconductor device 1, and the semiconductor device 1 and the substrate 6 are mechanically joined. In order to improve connection reliability, a gold plating layer 11 may be formed on the terminal electrode 5 as shown in FIG. (3) Joining with an anisotropic conductive adhesive As shown in FIG.
Is provided with a bump electrode 3 made of gold, and a gap between the semiconductor device 1 and the substrate 6 is filled with an anisotropic conductive adhesive in which conductive particles are dispersed in a binder, and heated under pressure. The anisotropic conductive adhesive is cured to cure the anisotropic conductive adhesive layer 1
By forming 3, the semiconductor device 1 and the substrate 6 are mechanically joined while the bump electrodes 3 are electrically connected to the terminal electrodes 5 on the substrate 6. (4) Bonding with conductive adhesive As shown in FIG.
Is provided with a bump electrode 3 made of gold, a conductive adhesive is transferred to the bump electrode 3, the bump electrode 3 is aligned with the terminal electrode 5 on the substrate 6, and then the conductive adhesive is cured. Then, the bump electrode 3 and the terminal electrode 5 are electrically connected via the conductive adhesive layer 4. Thereafter, the gap between the semiconductor device 1 and the substrate 6 is filled with a sealing material, and the sealing material is cured to form a sealing layer 7, whereby the semiconductor device 1 and the substrate 6 are mechanically joined. As the sealing material, a composition mainly containing a resin binder containing a cresol novolak type epoxy resin and a novolak type phenol resin (curing agent) and a filler made of insulating particles is generally used.

[0004]

However, each of the above mounting methods has the following problems.

[0005] The mounting methods (1) and (2) have a structure in which it is difficult to relieve the thermal stress generated due to the difference in expansion coefficient between the semiconductor device and the substrate, so that the connection stability over a wide temperature range. There is a limit to the applications where is required.

In the mounting method (3), the use of a highly flexible resin material for the resin binder in the anisotropic conductive adhesive makes it possible to reduce the thermal stress. Therefore, connection stability in a high humidity environment becomes a problem. The thermal stress can also be reduced by adjusting the coefficient of thermal expansion of the binder to the semiconductor device or the substrate, but in this case, the initial connection reliability is deteriorated because a large amount of filler having a low coefficient of expansion is contained. There is a fear.

In the mounting method (4), thermal stress can be reduced by making the conductive adhesive flexible and adjusting the thermal expansion coefficient of the sealing material to the semiconductor device and the substrate. Therefore, it can be said that this mounting method (4) is a promising method among the methods in the flip chip mounting method.

However, even in the mounting method (4), the sealing material made of the composition obtained by mixing the cresol novolak type epoxy resin and the novolak type phenol resin as described above has a high viscosity and a low thermal expansion coefficient. In order to match the device and the substrate, the ratio of the amount of the filler in the sealing material must be increased, and as a result, the sealing material has a high viscosity. For this reason, when filling a sealing material between a semiconductor device and a board | substrate, it was necessary to heat a sealing material to 70-80 degreeC or more, and to reduce a viscosity. As a result, productivity is poor,
In addition, there is a problem that the conductive connection portion is damaged at the time of encapsulating the sealing material due to thermal stress caused by a difference in thermal expansion coefficient when the temperature rises, and connection reliability is reduced.

On the other hand, it is conceivable to use a resin binder having a very low viscosity at room temperature, which is mainly composed of a polyepoxide and an acid anhydride, as a sealing material. However, when a large amount of filler is added to the resin binder to reduce the coefficient of thermal expansion, the viscosity of the sealing material is low but the thixotropic index is high. As a result, sealing cannot be performed between the semiconductor device and the substrate, or even if the sealing can be performed, a large amount of air bubbles are embraced, and the thermal expansion of the sealing material cured by the air bubbles becomes uneven depending on the location, thereby improving connection reliability. There was a problem that the sealing material was lowered, so that a sealing material using a resin comprising a polyepoxide and an acid anhydride as a binder was not practical.

[0010] It is an object of the present invention to determine the limits of viscosity and thixotropy necessary for obtaining good sealing properties of a sealing material, and to establish a connection by using a sealing material satisfying such viscosity and thixotropy. An object of the present invention is to provide a semiconductor device having high reliability and high productivity and a mounting method thereof.

[0011]

The inventor of the present invention has found that the reason that the conventional materials are difficult to use as a sealing material is that not only the viscosity but also the thixotropic index of the sealing material is high. For example, it has been found that in a resin binder containing a polyepoxide and an acid anhydride, the flowability is inhibited by the interaction between a free acid in the acid anhydride and a polar group on the filler surface. In view of this fact, the following measures are taken in order to achieve the above object.

Means taken by the present invention is to provide a sealing material having a viscosity of 100 Pa · s in a flip chip mounting method.
In the following, a composition having a thixotropy index of 1.1 or less is used, and a semiconductor device and a substrate are mechanically connected by a sealing layer obtained by curing the composition.

A semiconductor device package according to the present invention comprises a semiconductor device having an electrode pad, a substrate having a terminal electrode, a bump electrode provided on the electrode pad of the semiconductor device, an organic adhesive and a conductive material. A conductive adhesive layer comprising a flexible conductive adhesive containing a conductive material and electrically connecting the bump electrode to a terminal electrode on a substrate; and the semiconductor device comprising a cured composition. And a sealing layer that fills the gap between the substrate and mechanically joins the two, and the composition comprises a resin binder containing at least a polyepoxide, a carboxylic anhydride, a rheology modifier, and a latent curing catalyst. And a filler composed of an insulating substance as a main component, and the rheology modifier has a function of inhibiting an interaction between a free acid in the carboxylic anhydride and a polar group on the surface of the filler. That.

According to this structure, in the semiconductor device mounting body in which the semiconductor device is mounted on the substrate, the sealing layer for mechanically joining the semiconductor device and the substrate has a low viscosity and a low viscosity in a liquid mounting process. Since it has a thixotropic index,
When the sealing material is injected in the mounting step, the sealing material quickly penetrates into the small gap without generating bubbles, and the injection temperature can be lowered. These properties improve the electrical connection reliability such as the adhesion between the semiconductor device and the substrate and the thermal shock resistance, and also improve the productivity. In particular, the use of a rheology modifier that has the function of inhibiting the interaction between the free acid in the acid anhydride and the polar group on the surface of the filler achieves low viscosity and a low thixotropy index. Will do.

In the package of the semiconductor device, the rheology modifier is preferably composed of a Lewis base compound.

In the above semiconductor device package, the rheology modifier may be a tertiary amine compound, a tertiary phosphine compound, a quaternary ammonium salt, a quaternary phosphonium salt, and a heterocyclic compound containing a nitrogen atom in a ring. More preferably, it is constituted by at least one of them.

Thus, since the sealing material is mainly composed of an acid anhydride-curable epoxy resin and an insulating material having a small coefficient of thermal expansion, the thermal stress acting on the sealing layer is reduced. I do.

In the semiconductor device package, it is preferable that the carboxylic acid anhydride in the resin binder contains at least a cyclic aliphatic acid anhydride.

In this case, the cyclic aliphatic acid anhydride may contain at least a trialkyltetrahydrophthalic anhydride.

Thus, it is possible to ensure good moisture resistance of the resin binder by utilizing the properties of the cyclic aliphatic acid anhydride having low water absorption. Also, since the viscosity of the liquid resin binder is low in the mounting process of the semiconductor device,
By closing the sealing material in a short time, the cost of the semiconductor device can be reduced.

In the above-mentioned semiconductor device mounted body, it is preferable that the bump electrode of the semiconductor device is formed of a stud bump electrode having a two-step projection shape.

Thus, the number of bump electrodes of the semiconductor device can be increased. Then, when the semiconductor device is mounted on the substrate, when the sealing material is injected into the gap between the bump electrodes provided at a high density and the terminal electrodes on the substrate after electrically connecting the bump electrodes, a low viscosity is obtained. By using a sealing material having a low thixotropy index, it is possible to sufficiently spread the sealing material even in a small gap. Therefore,
Even in a semiconductor device formed by high-density mounting, the reliability of electrical connection and mechanical bonding between the semiconductor device and the substrate is improved.

A sealing material for mounting a semiconductor device according to the present invention is a sealing material for filling a gap between a semiconductor device and a substrate and connecting the semiconductor device and the substrate, and includes a polyepoxide, a carboxylic anhydride, and a rheological modification. 80 to 25% by weight of a resin binder containing at least an agent and a latent curing catalyst, and a filler of 20 to 75% by weight of an insulating material. The rheology modifier has a function of inhibiting an interaction between a free acid in the carboxylic anhydride and a polar group on the surface of the filler.

With this configuration, the sealing material has a low viscosity (100
Pa.s or less) and a low thixotropy index (1.1 or less), so that when the sealing material is injected in the mounting process, it quickly penetrates into the gaps quickly and without bubbles, and sufficiently penetrates into the small gaps. It is also possible to lower it. In addition, the latent curing catalyst ensures the stability of the sealing material in the storage state and a practical curing acceleration function. Therefore, the electrical connection reliability including the adhesion between the semiconductor device and the substrate in the mounted body and the thermal shock resistance are improved, and the productivity is also improved.

In the above sealing material for mounting a semiconductor device,
The rheology modifier is preferably composed of a Lewis base compound.

In the above-mentioned sealing material for mounting a semiconductor device,
The rheology modifier may be at least one of a tertiary amine compound, a tertiary phosphine compound, a quaternary ammonium salt, a quaternary phosphonium salt, and a heterocyclic compound containing a nitrogen atom in the ring.

As a result, a material having a small coefficient of thermal expansion between an acid anhydride-curable epoxy resin and an insulating material is mainly used as a sealing material, so that it acts on a sealing layer in a mounted body to be formed. Thermal stress is reduced. In addition, low viscosity and low thixotropy index are achieved by using a rheology modifier that has the function of inhibiting the interaction between the free acid in the acid anhydride and the polar group on the surface of the filler. Will do.

In the sealing material for mounting the semiconductor device,
The carboxylic acid anhydride in the resin binder may contain at least a cyclic aliphatic acid anhydride.

In this case, the cyclic aliphatic acid anhydride may contain at least a trialkyltetrahydrophthalic anhydride.

Thus, it is possible to ensure good moisture resistance of the resin binder by utilizing the properties of the cyclic aliphatic acid anhydride having low water absorption. Also, since the viscosity of the liquid resin binder is low in the mounting process of the semiconductor device,
By completing the encapsulation of the sealing material in a short time, the mounting cost can be reduced.

In the sealing material for mounting the semiconductor device,
When the equivalent ratio of the carboxylic anhydride to the polyepoxide is 0.8 to 1.1, and the weight ratio of the curing catalyst to the entire resin binder is 0.3 to 3,
%, The composition preferably has a composition in which the weight ratio of the rheology modifier to the entire resin binder is 0.02 to 0.3%.

[0032]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a cross-sectional view showing a mounted body of the semiconductor device according to the embodiment, and FIG. 2 is a partial cross-sectional view showing the vicinity of the connection portion in an enlarged detail. Are formed by the above-described flip chip mounting method. 1 and 2, reference numeral 1 denotes an LSI.
Reference numeral 2 denotes a semiconductor device such as a chip, and reference numeral 2 denotes an electrode pad provided on a part of the semiconductor device 1. Reference numeral 3 denotes a bump electrode made of gold, and reference numeral 4 denotes a conductive adhesive layer composed of a composition (conductive adhesive) mainly containing a special epoxy resin and a conductive powder such as a silver palladium (AgPd) alloy. Is shown. Reference numeral 6 denotes a substrate such as a ceramic substrate for mounting the semiconductor device 1, and reference numeral 5 denotes a terminal electrode on the substrate 6. Reference numeral 7 denotes a sealing layer composed of a sealing material containing an acid anhydride-curable epoxy resin as a main component. The sealing material 7 has a thixotropy index of 1.1 or less and a viscosity of 100 Pa · s in a fluidized state before curing, and the sealing material is formed between the semiconductor device 1 and the substrate 6 by using a capillary phenomenon. After injection, it is cured. Here, the thixotropy index is an index represented by Δη / Δε when a shear rate is ε and a viscosity is η.
The values when the shear rate is 2 (1 / sec) to 20 (1 / sec) are shown.

FIG. 3 is a cross-sectional view showing a semiconductor device mounting body formed by a flip chip mounting method using so-called stud bump electrodes. The package of the semiconductor device shown in FIG. 3 is basically the same as the package of the semiconductor device shown in FIG. 1, but the package of the semiconductor device shown in FIG. The only difference is that a stud bump electrode 14 having a two-step projection is used in place of the above. By adopting the flip-chip mounting body using the stud bump electrodes 14 as described above, there is an advantage that it can be applied to a semiconductor device in which a larger number of electrode pads are provided at a high density, as described later in detail.

Next, the stud bump electrode 14 shown in FIG.
FIG. 4 (a) shows a flip chip mounting process using
This will be described with reference to FIGS. FIG. 4 (a)
5A to 5E are cross-sectional views illustrating a change in the mounting body of the semiconductor device in the flip-chip mounting process, and FIG. 5 is a flowchart illustrating a flow of the flip-chip mounting process.
Hereinafter, the mounting process will be described along the steps shown in FIG.

First, in step ST1, a stud bump electrode 14 is formed on each electrode pad 2 of the semiconductor device 1 (LSI chip) using an Au wire.
Then, a leveling step of pressing a flat surface with each stud bump electrode 14 is performed to align the positions of the tip surfaces of the stud bump electrodes 14.

Next, in step ST3, FIG.
As shown in (c), the semiconductor device 1 is positioned above the substrate 20 coated with the conductive adhesive 4a with the stud bump electrode 14 facing downward, and lowered from that state. After the stud bump electrodes 14 are immersed in the conductive adhesive 4a, the semiconductor device is pulled up, and the conductive adhesive 4a is collectively transferred to each stud bump electrode 14.

Next, in steps ST4 and ST5, FIG.
As shown in (d), the semiconductor device 1 is mounted on a ceramic substrate 6 on which a large number of terminal electrodes 5 are provided. At this time, each stud bump electrode 14 of the semiconductor device 1
And the respective terminal electrodes 5 on the substrate 6 are aligned with each other,
The conductive adhesive is cured by heating to form the conductive adhesive layer 4.
To form Thus, the stud bump electrodes 14 of the semiconductor device 1 and the terminal electrodes 5 of the substrate 6 are electrically connected.

Next, in step ST6, the connection state is inspected. If the electrical connection state is not good (NG), the chip (semiconductor device) is replaced in step ST7, and then the operation proceeds to step ST4. On the other hand, if the electrical connection state is good (OK), the process proceeds to step ST8.

Next, in step ST8, a low viscosity (100
(Pa · s or less) and a sealing material made of a composition having a low thixotropy index (1.1 or less) is injected into the gap between the semiconductor device 1 and the substrate 6 at room temperature to perform resin sealing of the connection portion. Then, in step ST9, the resin binder in the sealing material is cured by heating. At this time, FIG.
As shown in FIG. 5, a sealing layer 7 is formed, and the semiconductor device 1 and the substrate 6 are mechanically joined by the sealing layer 7.

Thereafter, in step ST10, a final inspection is performed, and the flip chip mounting process is completed.

The sealing material used in the flip chip mounting process has a low viscosity and a low thixotropy index.
Even at a low temperature of about room temperature, the injection of the sealing material is performed quickly, and the sealing material spreads sufficiently even in a small gap. Therefore, the time required for sealing can be shortened, and the connection reliability of the joint connected via the conductive adhesive 4 can be maintained. Furthermore, since the encapsulant is a composition mainly composed of an acid anhydride-curable epoxy resin having improved fluidity and a filler such as fused silica, the thermal expansion coefficient after curing is low. Having. As described above, since the coefficient of thermal expansion of the sealing layer 7 is low, it is possible to suppress the thermal stress generated from the difference in coefficient of thermal expansion between the silicon substrate forming the semiconductor device 1 and, for example, the alumina substrate forming the substrate 6.
In addition, since the sealing material made of such an epoxy resin has high heat resistance and high adhesive strength, stable connection reliability can be achieved even in a high temperature and high humidity environment.

Since the conductive adhesive 4 has high flexibility, thermal stress can be reduced, and connection stability is improved.

As described above, according to the above-described flip-chip mounting process, it is possible to connect the semiconductor device 1 and the substrate 6 with extremely high reliability and stably.

In the embodiment, the bump electrode 3 is made of gold. However, the material is not limited to gold.
For example, it may be formed of another metal such as copper. In addition, the shape of the bump electrode is not particularly limited to the above-described stud bump electrode, and any bump electrode that is generally used for flip-chip mounting can be applied. However, by using the stud bump electrodes as shown in FIGS. 3 and 4A to 4E, the spread of the conductive adhesive layer 4 in the lateral direction can be suppressed, so that the mounting density is greatly improved. Can be achieved.

The material of the conductive adhesive 4 is not limited to the epoxy type, and any material may be used as long as it has flexibility. For example, rubbers such as SBR, NBR, IR, BR, CR, etc., acrylics, polyesters, polyamides, polyethers, polyurethanes, polyimides, and silicones can be used. As the material of the conductive powder contained in the conductive adhesive, any material may be used as long as it is generally used, for example, noble metal powder such as silver, gold, and palladium, base metal powder such as nickel and copper, solder, silver palladium and the like. Alloy powders, composite powders such as silver-plated copper powders, and conductive non-metallic powders such as carbon. These conductive powders can be used alone or in combination of two or more. The particle size and shape of these conductive powders are not particularly limited.

On the other hand, the sealing material is mainly composed of a resin binder and a filler. The resin binder contains polyepoxide, an acid anhydride and a rheology modifier as essential components. The polyepoxide in the resin binder used here is not particularly limited as a component, and those commonly called epoxy compounds and epoxy resins are used. For example, a bisphenol type epoxy resin represented by a general structural formula shown in FIG. 6, a novolak type epoxy resin, a glycidyl ether type epoxy resin, a glycidyl ester type epoxy resin, a glycidylamine type epoxy resin, an alicyclic type epoxy resin , Biphenyl type epoxy resin,
Examples include a naphthalene type epoxy resin, styrene oxide, alkyl glycidyl ether, and alkyl glycidyl ester. These can be used alone or in a mixture of two or more.

As the acid anhydride used here, those usually used as a curing agent for epoxy compounds and epoxy resins can be used. The most preferred example is a trialkyltetrahydrophthalic anhydride having a structure represented by the general structural formula shown in FIG. Also,
Other preferred examples include methyltetrahydrophthalic anhydride and methylhexahydrophthalic anhydride, cycloaliphatic compounds such as methylhymic anhydride and those which are liquid at 25 ° C. However, the present invention is not limited to this. These can be used alone or in a mixture of two or more. In particular, by using the above as a main component of the resin binder, a sealing material having very low viscosity, high heat resistance, high moisture resistance, and high adhesion can be obtained.

As the resin binder of the sealing material, in addition to the above essential components, heat resistance, moisture resistance, adhesion strength,
A third binder component may be added as needed for the purpose of adjusting the coefficient of thermal expansion, adjusting the rheology, adjusting the reactivity, and the like.

The filler in the sealing material has an average particle size of 1
A powder having a size of about 50 μm may be used, but preferred examples include oxide compounds such as silica and alumina, nitride compounds such as aluminum nitride, carbide compounds such as silicon carbide, and silicide compounds.
It is desirable that the material be thermally stable and have a low coefficient of thermal expansion. These filler components can be used in any combination of two or more. The amount of the filler is not particularly limited, but is preferably 20 to 80% by weight based on the total amount of the sealing material. By using these filler components, it is possible to realize a sealing material that is excellent in insulating properties and generates little thermal stress.

As the rheology modifier for improving the fluidity of the sealing material, the interaction between the free acid in the acid anhydride and the polar group on the surface of the filler is cut off to obtain a thixotropic index of the sealing material. There is no particular limitation on the method as long as it has the effect of lowering.

Preferred examples are: (1) Aging by mixing a part of the acid anhydride and the filler in advance (or aging by heating to 100 ° C. or less)
After that, a method of obtaining a sealing material by adding a polyepoxy compound and the remaining filler and other additives (2) A substance which selectively adsorbs free acids in an acid anhydride is added to the sealing material. Method (3) A method in which a substance that interacts with the free acid stronger than the polar group on the filler surface (such as a Lewis base compound containing no NH 2 group or OH group) is added to the sealing material. .

However, the Lewis base compound mentioned here includes a tertiary amine compound, a tertiary phosphine compound, a quaternary ammonium salt such as tetrabutylammonium bromide, and a quaternary phosphonium such as tetrabutylphosphonium benzotriazolate. Heterocyclic compounds containing a nitrogen atom in the ring, such as salts and melanin imidazole compounds. However, these are merely examples, and there are a very large number of Lewis base compounds, and such Lewis base compounds can be used alone or as a mixture of two or more.

As constituents of the sealing material, a rheology adjuster such as a solvent, a dispersant, and a leveling agent, an adhesion improver such as a coupling agent, and a reaction adjuster such as a curing catalyst may be used as necessary. it can.

The rheology modifier composed of a Lewis base compound such as an amine compound used in the present invention is usually used also as a curing catalyst for curing a polyepoxide with a carboxylic anhydride.

However, when the rheology modifier is used as a curing catalyst for a sealing material, the reaction proceeds even during storage at a low temperature to cause gelation. I have no choice. On the other hand, it is indispensable to use a one-pack type sealing material for LSI because the filler must be uniformly dispersed in a large amount.

That is, the rheology modifier referred to in the present invention is used as a curing catalyst for a two-component sealing material, but is not used for a one-component sealing material.

On the other hand, if the addition amount is reduced to such an extent that it does not gel during storage, it cannot be applied as a curing catalyst for a one-part sealing material, but in that case, the curing acceleration function is too low. However, under practical curing conditions, high sealing material curing characteristics cannot be obtained.

A feature of the present invention is that a latent curing catalyst is used as a curing catalyst for providing a storage stability as a one-part solution and a practical curing acceleration function, and a conventional curing catalyst such as amine is used.
The point is that a substance used as a curing catalyst for a liquid sealing material is used as a rheology modifier. Such a rheology modifier is added in such a small amount that it does not exhibit a curing function, but is added in such an amount that it has a function of improving interface characteristics.

However, a latent curing catalyst refers to a catalyst whose catalytic activity rapidly increases when energy such as heat is applied thereto, and is usually melted (liquefied) or dissociated by the application of energy. The activity increases.

From the above viewpoints, the composition of the sealing material and the resin binder in the sealing material preferably have the following composition ratio.

Resin binder 80 to 25% by weight Filler component 20 to 75% by weight However, polyepoxide, carboxylic anhydride, curing catalyst and rheology modifier which are components in the resin binder may have the following component ratio. preferable.

Carboxylic anhydride / polyepoxide 0.8 to 1.1 equivalent ratio Curing catalyst / resin binder 0.3 to 3% by weight Rheology modifier / resin binder 0.02 to 0.3% by weight As for the substrate, a substrate made of a material such as a resin substrate such as a metal glaze substrate, a glass substrate, or a glass epoxy, a polymer film substrate, or the like can be applied in addition to a ceramic substrate such as alumina.

The material of the terminal electrode 5 is not particularly limited.

[0065]

Next, a description will be given of a specific embodiment performed for examining characteristics of a semiconductor device obtained by the above-described flip chip mounting process.

Example 1 A semiconductor device having the structure shown in FIG. 1 is formed by the steps shown in FIGS. At this time, the bump electrodes 3 are formed by gold plating. The conductive adhesive 4a is composed of a composition containing silver palladium powder and a flexible epoxy resin as main components, and is cured by heating to 120 ° C. Further, using a sealing material having a composition a shown in Table 1 below, the sealing material is cured at 150 ° C.

Embodiment 2 The stud bump electrodes 14 shown in FIG. 3 are formed on the electrode pads 2 of the semiconductor device 1 by a wire bonder using gold. Subsequent steps are performed under the same steps and conditions as in the first embodiment.

Example 3 The semiconductor device 1 is mounted on the substrate 6 under the same conditions as in Example 1 except that the sealing material is injected under reduced pressure.

Example 4 The semiconductor device 1 was mounted on the substrate 6 under the same conditions as in Example 2 except that the composition of the sealing material was changed to the composition b shown in Table 1.

(Example 5) The semiconductor device 1 is mounted on the substrate 6 under the same conditions as in Example 2 except that the substrate 6 is a glass epoxy substrate and the composition of the sealing material is the composition c in Table 1.

(Example 6) The same procedure as in Example 2 was carried out except that the substrate 6 was a glass epoxy substrate, the conductive powder in the conductive adhesive 4 was silver powder, and the composition of the encapsulant was as shown in Table 1. The semiconductor device 1 is mounted on the substrate 6 under the same conditions.

(Example 7) The sealing material was changed to a composition e shown in Table 1 with the substrate 6 being a glass substrate, the conductive adhesive 4 being mainly composed of silver powder and urethane resin, and the composition of the sealing material being as shown in Table 1. The semiconductor device 1 is mounted on the substrate 6 under the same conditions as in Example 2 except that the implantation of GaAs is performed under reduced pressure.

(Embodiment 8) The bump electrode 3 shown in FIG.
It is formed on the electrode pad 2 of the semiconductor device 1 by gold plating. In the subsequent steps, the semiconductor device 1 is mounted on the substrate 6 under the same steps and conditions as in the seventh embodiment.

(Comparative Example 1) The composition of the sealing material was changed to the composition f shown in Table 1.
Semiconductor device 1 under the same conditions as in Example 2 except that
Is mounted on the substrate 6.

(Comparative Example 2) The composition of the encapsulant was adjusted according to the formulation g in Table 1.
Semiconductor device 1 under the same conditions as in Example 2 except that
Is mounted on the substrate 6.

Table 1 below shows the contents of the above formulations a to g.

[0077]

[Table 1]

(Comparative Example 3) The semiconductor device 1 is mounted on the substrate 6 by the conventional method shown in FIG. At this time, an alumina substrate was used as the substrate 6, and the bump electrodes 3 were formed of gold.
The terminal electrode 5 is plated with indium. Bump electrode 3
After positioning the semiconductor device 1 with the jig, the semiconductor device 1 is heated to 170 ° C. while pressing the bump electrode 3 with the jig.
And the terminal electrode 5 are connected. Further, the semiconductor device 1
A silicone sealing material (no stress type) is injected into the gap between the substrate and the substrate 6 and cured to form a sealing layer 10.

(Comparative Example 4) The semiconductor device 1 is mounted on the substrate 6 by the conventional method shown in FIG. At this time, the bump electrode 3 is formed of gold, and the gold plating layer 11 is formed on the terminal electrode 5.
Is formed, and an acrylic sealing material is coated thereon. After the bump electrodes 3 and the terminal electrodes 5 are aligned, the sealing material is cured by ultraviolet irradiation or heating while pressing the semiconductor device 1 with a jig to form the sealing layer 12.

(Comparative Example 5) The semiconductor device 1 is mounted on the substrate 6 by the conventional method shown in FIG. At this time, the bump electrode 3 is formed of gold, and the substrate 6 is formed of alumina. The substrate 6 is coated with an anisotropic conductive adhesive in which gold particles are dispersed in an epoxy binder. After the bump electrodes 3 and the terminal electrodes 5 are aligned, the anisotropic conductive adhesive is cured by irradiating ultraviolet light or heating while pressing the semiconductor device 1 with a jig to form the anisotropic conductive adhesive layer 13. Then, the bump electrodes 3 and the terminal electrodes 5 are electrically and mechanically connected.

Table 2 below shows the viscosities and thixotropy indices of the encapsulants used for the semiconductor devices shown in Examples 1 to 8 and Comparative Examples 1 to 5 and the time required for injecting the encapsulant.

[0082]

[Table 2]

In Examples 1 to 8, the injection time was as short as several minutes or less, and it can be seen that the injection time is suitable for practical use. For it,
In Comparative Examples 1 and 2, the injection time was as long as several tens of minutes,
Not suitable for practical use. And it is shown that there is a correlation between such an injection time and the viscosity and the thixotropic index. That is, in Examples 1 to 8, all have low viscosity (100 Pa · s or less) and low thixotropy index (1.1 or less), so that the time for encapsulating the sealing material is short. On the other hand, the viscosity was 100 Pa ·
When the value exceeds s or the thixotropic index exceeds 1.1 as in Comparative Example 1, the injection time becomes extremely long. Therefore, the viscosity of the sealing material is 100 Pa · s
It can be seen that when the thixotropy index is 1.1 or less, the fluidity of the sealing material is improved to a level that can withstand practical use.

In order to evaluate the connection stability of the semiconductor devices shown in Examples 1 to 8 and Comparative Examples 1 to 5, the results of an environmental resistance test, and the methods and conditions of the environmental test are shown in Table 3 below. , And Table 4 respectively.

[0085]

[Table 3]

[0086]

[Table 4]

The results of the evaluations shown in the above tables will be described below.

In any of the first to eighth embodiments, there is no problem in connection stability even after the reliability tests. In addition, any of the sealing materials used therein has a low viscosity (100 Pa).
S or less) and a low thixotropy index (1.1 or less), and the encapsulation time of the sealing material is short. That is, regardless of the structure of the bump electrode, the type of the substrate, various additives, the type of the conductive adhesive, etc., the sealing having a low viscosity (100 Pa · s or less) and a low thixotropy index (1.1 or less). This shows that the use of the stopper material can provide a semiconductor device package having excellent environmental resistance such as thermal shock resistance and high productivity.

Also, in Examples 1 to 8, the rheology modifier was a Lewis base having a function of allowing the polar group on the filler surface to interact with the free acid more strongly than that of the free acid. Although compounds are used, they not only modify the rheology but also act as a catalyst for the reaction between polyepoxide and acid anhydride, so that the encapsulant has improved environmental resistance such as heat resistance.

On the other hand, when the thixotropic index is high even when a low-viscosity encapsulant is used as in Comparative Example 1, it takes time to inject the encapsulant. In the heat resistance test and the thermal shock test, there is also a connection part that is disconnected. This is presumably because air bubbles are entrapped in the sealing material layer during the injection of the sealing material, and the thermal stress applied to the sealing layer during the test becomes non-uniform, causing damage to the conductive connection portion.

Even when a highly flexible conductive adhesive is used, in Comparative Example 2 in which a high-viscosity resin such as a phenol-curable epoxy resin is used as the sealing material, Has to be heated and implanted, and a connection portion having a high connection resistance value at the time of implantation appears. Further, when each reliability test is performed thereafter, a portion where the connection portion is unstable in the thermal shock test may be disconnected. This is considered to be because the viscosity of the sealing material is high and the joint of the conductive adhesive is damaged by stress at the time of injection of the sealing material.

In Comparative Examples 3 and 4, the connection is broken in a relatively short time in the thermal shock test. In Comparative Example 4, the change in the connection resistance was large in both the high humidity test and the solder heat resistance test. It is considered that the reason is that the disconnection occurs in Comparative Example 3 because the joint cannot reduce the thermal stress. In Comparative Example 4, it is considered that the thermal stress generated from the sealing material was large and the water absorption of the sealing material was high.

In Comparative Example 5, the connection resistance increased significantly in the high-temperature storage test, the high-humidity storage test, and the soldering heat resistance test. This is considered to be because the moisture resistance of the binder of the anisotropic conductive adhesive is low and the adhesion at high temperature is low.
When an anisotropic conductive adhesive composed of a binder having high moisture resistance is used, disconnection of a connection portion occurs in a thermal shock test.

As can be seen from these evaluation results, the semiconductor device package according to the present invention has high reliability in any environment. However, conventionally, a resin containing a polyepoxide and an acid anhydride (curing agent) as a resin binder has not been generally used as a sealing material in a flip chip mounting process using a conductive adhesive. The reason is that when a resin binder composed of a polyepoxide and an acid anhydride (curing agent) is used as a sealing material in the mounting of a semiconductor device, the thixotropy index of the sealing material increases, so that a part of the gap between the semiconductor device and the substrate is used. It is thought that there is a problem that the injection can be performed only to the injection.

In the present invention, it has been found that the problem of high thixotropy index is due to the interaction between the free acid contained in the acid anhydride and the polar groups on the surface of the insulating filler. It has been found that this problem can be solved by taking measures to inhibit the interaction.

Another reason why a resin binder containing a polyepoxide and an acid anhydride (curing agent) has not been conventionally used as a sealing material is that polyepoxide and an acid anhydride (curing agent) are used. It is generally known that resin binders undergo hydrolysis in a high-humidity atmosphere. Therefore, if these resin binders are used as a sealing material, problems will occur in the moisture resistance and reliability of the connection using a conductive adhesive. Probably because it was thought.

Therefore, in the present invention, as shown in each of the above embodiments, a resin binder using an acid anhydride (particularly, one containing trialkyltetraethylene hydrophthalic anhydride as a main component) as a hardener is used. Even when used as a sealing material in a flip chip mounting process of the device, it was confirmed that the formed sealing layer had sufficient moisture resistance to withstand practical use. In addition, since the sealing material containing a resin binder having such a composition as a main component has a low viscosity and a low thixotropy index, it has a good property that it can penetrate quickly and into small gaps even when injected at a low temperature of about room temperature. Was found to have. From these properties, excellent properties such as high thermal shock resistance can be exhibited.

On the other hand, in the conventional semiconductor device package using the resin binder having the composition f shown in Table 1 in the flip chip mounting process, since the sealing material has a high thixotropy index, bubbles are generated in the sealing layer. It is considered that the conductive connection is damaged during the soldering heat resistance test and the thermal shock test. In addition, a conventional semiconductor device mounting body using a resin binder having the composition g in Table 1 in the flip chip mounting process has a high viscosity,
Since the resin binder needs to be injected while being heated to about 0 ° C., it is considered that the conductive connection portion is damaged and the impact resistance is deteriorated.

[0099]

According to the semiconductor device package of the present invention,
A composition mainly comprising a resin binder containing at least a polyepoxide, a carboxylic anhydride, a rheology modifier and a latent curing catalyst, and a filler made of an insulating material, wherein the rheology modifier is a carboxylic anhydride. Use a material that has the function of inhibiting the interaction between the free acid in the product and the polar group on the surface of the filler, and mechanically connect the semiconductor device and the substrate with a sealing layer obtained by curing this. With this configuration, it is possible to eliminate bubbles in the sealing layer and to reduce the thermal stress.
It is possible to improve the reliability of electrical connection such as adhesion between substrates and thermal shock resistance, and to improve productivity.

According to the sealing material for mounting a semiconductor device of the present invention, a resin binder containing a polyepoxide, a carboxylic anhydride, a rheology modifier and a latent curing catalyst, and a filler made of an insulating material are prescribed. And the rheology modifier has a function to inhibit the interaction between the free acid in the carboxylic acid anhydride and the polar group on the filler surface, so that a low thixotropic index with low viscosity is obtained. A sealing material having the above-mentioned excellent characteristics can be used as a sealing material having the storage stability by the latent curing catalyst and the practical curing promoting function. Can be provided.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a structure of a semiconductor device according to an embodiment.

FIG. 2 is a partial cross-sectional view illustrating a connection portion of the semiconductor device shown in FIG. 1 in an enlarged manner in detail.

FIG. 3 is a cross-sectional view illustrating a structure of a semiconductor device formed by a stud bump method according to the embodiment.

FIG. 4 is a cross-sectional view illustrating a change in the structure of the semiconductor device according to the embodiment in a flip-chip mounting process.

FIG. 5 is a flowchart illustrating a procedure of a flip-chip mounting process of the semiconductor device according to the embodiment;

FIG. 6 is a view showing a general structural formula of a bisphenol-type epoxy resin in a resin binder used in the embodiment.

FIG. 7 is a view showing a general structural formula of a trialkyltetrahydrophthalic acid in a resin binder used in the embodiment.

FIG. 8 is a cross-sectional view showing a structure of a conventional semiconductor device connected by solder bump electrodes.

FIG. 9 is a cross-sectional view showing a structure of a conventional semiconductor device connected by a low melting point metal layer.

FIG. 10 is a cross-sectional view showing a structure of a conventional semiconductor device connected by a curing shrinkage stress of a sealing resin.

FIG. 11 is a cross-sectional view showing a structure of a conventional semiconductor device connected by an anisotropic conductive adhesive.

FIG. 12 is a cross-sectional view showing a structure of a conventional semiconductor device connected by a conductive adhesive.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Semiconductor device 2 Electrode pad 3 Bump electrode 4 Conductive adhesive layer 5 Terminal electrode 6 Substrate 7 Sealing layer 8 Solder bump electrode 9 Plating layer 10 Sealing layer 11 Gold plating layer 12 Sealing layer 13 Anisotropic conductive adhesive layer

──────────────────────────────────────────────────の Continued on the front page (72) Inventor Mitsuru Harada 1006 Kazuma Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. (56) References JP-A-64-26625 (JP, A) JP-A-2-199847 (JP, A) JP-A-5-21520 (JP, A) JP-A-6-61303 (JP, A) JP-A-6-333985 (JP, A) JP-A-8-250548 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01L 21/60 H01L 21/56 C08G 59/42 C09J 163/00

Claims (12)

(57) [Claims] A semiconductor device having an electrode pad; a substrate having a terminal electrode; a bump electrode provided on the electrode pad of the semiconductor device; an organic adhesive and a conductive material; A conductive adhesive layer that is formed of a conductive adhesive having an electrical connection between the bump electrode and the terminal electrode on the substrate; and a composition that is formed by curing the composition to fill a gap between the semiconductor device and the substrate. A sealing layer for mechanically joining the two, wherein the composition comprises a resin binder containing at least a polyepoxide, a carboxylic anhydride, a rheology modifier and a latent curing catalyst, and a filler made of an insulating material. Wherein the rheology modifier has a function of inhibiting an interaction between a free acid in the carboxylic anhydride and a polar group on the surface of the filler. Implementation of. 2. The semiconductor device package according to claim 1, wherein the rheology modifier includes a substance that selectively adsorbs a free acid in a carboxylic acid anhydride. body. 3. The semiconductor device package according to claim 1, wherein the rheology modifier is a tertiary amine compound, a tertiary phosphine compound, a quaternary ammonium salt, a quaternary phosphonium salt, and a nitrogen atom. A package of a semiconductor device, which is at least one of heterocyclic compounds contained in the semiconductor device. 4. The semiconductor device package according to claim 1, wherein the carboxylic acid anhydride in the resin binder contains at least a cyclic aliphatic acid anhydride. 5. The semiconductor device package according to claim 4, wherein the cyclic aliphatic acid anhydride contains at least a trialkyltetrahydrophthalic anhydride. 6. The semiconductor device package according to claim 1, wherein the bump electrode of the semiconductor device is a two-stage projecting stud bump electrode. 7. A sealing material for filling a gap between a semiconductor device and a substrate and connecting the semiconductor device and the substrate, wherein a weight ratio of at least 80 including at least a polyepoxide, a carboxylic anhydride, a rheology modifier, and a latent curing catalyst. ~ 25
% Of a resin binder, and a filler composed of an insulating material at a weight ratio of 20 to 75%, wherein the rheology modifier is characterized by a free acid in the carboxylic anhydride and a polar group on the surface of the filler. A sealing material for mounting a semiconductor device, the sealing material having a function of inhibiting the interaction of the semiconductor device. 8. The encapsulant for mounting a semiconductor device according to claim 7, wherein the rheology modifier is a Lewis base compound. 9. The sealing material for mounting a semiconductor device according to claim 7, wherein the rheology modifier is a tertiary amine compound, a tertiary phosphine compound, a quaternary ammonium salt, a quaternary phosphonium salt, and nitrogen. A sealing material for mounting a semiconductor device, which is at least one of heterocyclic compounds containing atoms in a ring. 10. The mounting material for a semiconductor device according to claim 7, wherein the carboxylic acid anhydride in the resin binder contains at least a cyclic aliphatic acid anhydride. Sealing material. 11. The mounting material for a semiconductor device according to claim 10, wherein the cyclic aliphatic acid anhydride contains at least a trialkyltetrahydrophthalic anhydride. Sealing material. 12. The sealing material for mounting a semiconductor device according to claim 7, wherein the resin binder has an equivalent ratio of the carboxylic anhydride to the polyepoxide of 0.8 to 1.1, and the curing catalyst Wherein the weight ratio of the rheology modifier to the entire resin binder is 0.02 to 0.3%, and the weight ratio of the rheology modifier to the entire resin binder is 0.02 to 0.3%. Sealing material for mounting.