JP2551370B2 - Semiconductor chip mounting method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor chip mounting method.

[0002]

2. Description of the Related Art The wider the distance between the connection electrode pad of a semiconductor chip and the metal pattern for connection of a substrate after the connection process is finished, the greater the cleaning of flux, the pouring of sealing resin, the thermal cycle life of the connection portion, etc. Desirable in terms of aspect. The warp amount of the glass ceramic substrate is, for example, 31.6 μm / 10.
Since it reaches about a square mm, the height of the bumps (hereinafter referred to as S bumps) formed on the connection electrode pads of the semiconductor chip and the connection metal patterns (hereinafter referred to as P bumps) of the substrate are increased, and the influence of the warp amount I want to make room to absorb (connection failure).

However, when the S bump is formed by the plating method, the plating thickness H and the lateral protrusion W are substantially equal to each other. Therefore, if the height of the S bump is increased, the lateral protrusion is also increased. I can't get a fine S bump bump.

It has been reported that when the material of the S bump is made of soft gold and the height is about several tens to 100 μm, the cushioning property is increased and the connection with the external connection terminal is facilitated.

A conventional semiconductor chip mounting method will be described in detail with reference to the drawings.

FIGS. 2A and 2B are side views for explaining the first conventional example. The semiconductor chip mounting method shown in FIGS. 2A and 2B is a semiconductor chip mounting method in which a semiconductor chip having connection electrode pads is directly mounted on the surface of a heat-resistant insulating substrate by face-down.
7, a step of printing the resin paste 103 on the surface of the metal pattern 122 for connection with the semiconductor chip 107 provided on the surface of the heat-resistant insulating substrate 101 on which (7) is uncured A step of attaching metal balls 104 (made of gold) as they are to the resin paste 103, (C) a step of curing the resin paste 103, (D)
The interval 151 is 50 ± 5μ due to the parallel adjustment tool 108
a step of pressurizing the surface of the metal sphere 104 so as to obtain m (E)
The step of facing the surface of the connection electrode pad 121 of the semiconductor chip 107 to the surface of the heat-resistant insulating substrate 101; (F) the step of aligning the position of the metal ball 104 with the position of the connection electrode pad 121 of the semiconductor chip 107. , (G) pressurize the connecting electrode pad 121 and the metal ball 104 (100 to 100).
300 g / one place) and the step of connecting to each other by heating (350 to 400 ° C.).

In this technique, the height corresponding to the plating thickness H can be secured without increasing the lateral protrusion W in the step (B), and the warp amount of the substrate (resin (Including the effect of paste) can be corrected. (See, for example, JP-A-2-28340)
The diameter of 04 is 60 to 70 μm, and the metal sphere 104 is crushed by the steps (D) and (G). As a result, the lateral protrusion W described above occurs to some extent, and the semiconductor chip 10
It is estimated that the distance between No. 7 and the heat resistant insulating substrate 101 is smaller than 50 ± 5 μm.

FIGS. 3A to 3C are side views for explaining the second conventional example. The purpose of this technique is to form a gold bump having a height, which is softer than a gold bump formed by a plating method, in a simple working process.

The semiconductor chip mounting method shown in FIGS. 3A to 3C is (A) a step of heating the sail nozzle 211 and the connecting electrode pad 202 of the semiconductor chip 201 to about 300 ° C., (B) A diameter of 100 μm is provided on the upper portion of the sailboat nozzle 211.
3 (a)] (C) A compressed nitrogen gas 215 is blown from the upper part of the shellet nozzle 211 to attach the gold ball 212 to the connection electrode pad 202 of the semiconductor chip. Temporary bump 217
(FIG. 3 (b)) (D) The shellet nozzle 211 is lowered, the temporary bumps 217 are pressed against the connection electrode pads 202 of the semiconductor chip and thermocompression bonded to form S bumps 217b. Step (FIG. 3C) (E) The step of connecting the S bump to the connecting metal pattern of the substrate directly by pressure bonding or soldering. (See, for example, Japanese Patent Laid-Open No. 59-72737) Since the tip of the S bump 217b is thin, this portion is compressed in the step (E) and it is possible to contribute to the absorption of the warp of the substrate or the like. It can be easily inferred that P bumps may be formed on the heat resistant insulating substrate side instead of forming bumps.

In the step shown in FIG. 3B, the gold balls 212
The pressure applied to the temporary bumps 21 may be lower than the pressure generated by the wire bonder or the like, and in the step shown in FIG.
The pressure applied to 7 should be increased to the pressure generated by a wire bonder or the like.

FIG. 4 is a side view for explaining the third conventional example. The semiconductor chip mounting method shown in FIG.
(A) S bump 30 on electrode 304a of semiconductor element 301
3A forming step, (B) electrode 304 of wiring board 302
Step of forming P bump 303b on b, (C) Resin 30
5, the step of connecting the S bump 303a and the P bump 303b is included. (For example, JP-A-2-
This reference discloses that there is a method of forming both S bumps and P bumps and connecting them when the height is insufficient with only S bumps or P bumps. . In addition, if there is a problem in connection using resin, solder may be used, and at this time, it is suggested that the material of the S bump and P bump should be selected to have a melting point higher than that of the solder. There is. (If the flip chip in which the S bump is already formed by nail head bonding of a copper wire is used, only the P bump needs to be formed in the step (A).) Note that a gold ball or a piece of gold is used. A technique for forming a columnar S bump on a semiconductor element is disclosed in JP-A-63-
There is a technique disclosed in Japanese Patent No. 152152. According to the documents cited above, the gold bumps formed by the plating method tend to contain impurities and have high hardness.
It is not suitable because it requires high pressure.

5 (a) and 5 (b) are schematic side views for explaining a fourth conventional example. The semiconductor chip mounting method shown in FIGS. 5A and 5B is (A) the semiconductor chip 40.
(B) Land 4 of the substrate 402, which is a step of forming a bump 404 made of an Sn-based alloy and having a pointed substantially conical shape and a length of 100 μm on the Al pad 403 of No. 1;
05, a step of forming a base metal layer 406 having a melting point lower than that of the bumps 404, (C) the substrate 402 is heated to form the base metal layer 4
The bumps 404 are pressed against each other in a state that 06 is melted,
04a is inserted into the base metal layer 406 and welded. (For example, JP-A-5-14487
In the range of the width W of the semiconductor chip 401, the substrate 402
The warpage H is 70 μm. In FIG. 6B, which is the state in which the step (C) is completed, the protrusion 404a is completely melted and disappears, but the lateral width of the bump 404 expands until it contacts an adjacent bump (not shown). Does not reach. A portion of the protrusion 404b, which is 30 μm from the tip, is melted in the base metal layer 406b and barely makes an electrical contact.

The bump 404 is formed by heating the tip of the Sn alloy wire to form a ball.
3 is formed by cutting the wire by pulling the wire in a state of being crimped onto the wire. The length of the protrusion 404a can be set to a desired length by adjusting the heating temperature at the time of ball formation described above.

FIGS. 6A and 6B are sectional views for explaining the fifth conventional technique. The semiconductor chip mounting method shown in FIGS. 6A and 6B is (A) semiconductor chip 541.
(Or 551) a step of forming a bump electrode 542 (or 552) by providing a needle-like deposited metal on the electrode part, (B) pressing the bump electrode 542 (or 552) to the substrate electrode 544 (or 556) And (C) the bump electrode 542 (or 552) and the substrate electrode 544 (or 556) with the adhesive 545 (or the conductive adhesive 55).
7) The step of fixing (or connecting) using. (See, for example, Japanese Patent Laid-Open No. 4-144137) The needle-deposited metal is easily deformed by stress, and variations in height of the bump electrode (the substrate 543 (or 55)
5) (including warp) can be buffered.

FIG. 6 (a) shows the case where the needle-shaped deposits are soft, and FIG. 6 (b) shows that the needle-shaped deposits are hardened. It shows the case of applying 0.5 μm.

FIGS. 7A to 7E are shown in FIGS.
It is sectional drawing which shows the method of forming the acicular deposit metal shown to (b) in process order. The length of the acicular deposits is about 10 μm in 30 minutes of plating, but can be increased by increasing the energization time.

FIGS. 8A to 8C are a sectional view and a perspective view for explaining the sixth conventional technique. The semiconductor chip mounting method shown in FIG. 8A is (A) semiconductor element 601.
The process includes the steps of forming a protruding electrode 605 having a plurality of cavities 606 thereon, and (B) connecting the protruding electrode 605 so as to face the wiring pattern 606 of the substrate 607. (For example, see Japanese Patent Laid-Open No. 4-137630) When about 200 bumps are formed on a semiconductor element having a flat area of 9 mm × 6 mm and a thickness of 0.5 mm, the height of the semiconductor element from the active surface varies. Is 20 to 30 μm. When the protruding electrode 605 is pressure-connected to the substrate 607,
The protruding electrode 605 is easily plastically deformed, and a good connection can be obtained.

FIG. 8B shows a case where the polyimide resin 615 is present in the protruding electrode 605. Since the resin 615 is deformed and held when the protruding electrode 605 is pressed and deformed, stress acts on the resin 615 and a force for restoring the protruding electrode 605 works. As a result, a stress that constantly presses the wiring pattern 608 is generated on the bump electrode 605, and the connection can be completed.

In FIG. 8C, a large number of minute protrusions 614 are formed at the portions in contact with the leads so that the protrusion electrodes 605 can be connected to the leads of the flexible substrate.
Since the minute protrusions 614 bite into the leads, the bonding strength is 2
Increase by about 0%.

[0020]

The above-mentioned conventional technique has a drawback in that a special process is required to form a bump with a protrusion on a semiconductor chip.

[0021]

A method of mounting a semiconductor chip according to the present invention comprises: (A) a step of forming a bumped ball bump on an electrode pad provided on the semiconductor chip using a wire bonder; A step of attaching the conductive paste to the upper surface of the bump ball bump by a transfer method, (C) a step of attaching the conductive paste to a mounting pad provided on the substrate by a screen printing method, (D) the (C) ) Step of mounting a metal ball on the conductive paste, (E)
Aligning the ball bumps with protrusions with the metal balls, and mounting the semiconductor chip on the substrate;
(F) The step of joining the ball bumps with protrusions 4, the metal balls, and the mounting pads.

[0022]

The present invention will be described in detail with reference to the drawings. 1 (a) and 1 (b) are side views for explaining one embodiment of the present invention.

The semiconductor chip mounting method shown in FIGS. 1 (a) and 1 (b) uses (A) a wire bonder to form 100 μm square aluminum electrode pads 3 provided on the semiconductor chip 1.
A step of forming a bump ball bump 4 having a diameter of 100 μm, a ball portion height of about 20 μm, and a protrusion height of about 10 μm made of copper. And (C) attaching the solder paste 5 to the mounting pads 7 provided on the substrate 2 by screen printing, (D) the (C)
A step of mounting a metal ball 6 having a diameter of 70 μm and made of gold on the solder paste 5 of (1), (E) aligning the bumped bump bump 4 and the metal ball 6, and placing the semiconductor chip 1 on the substrate 2 And (F) heating and melting the solder paste 5 to connect the bumped bumps 4, the metal balls 6 and the mounting pads 7 to each other.

The height of the bump is 100 μm, and the substrate 2
When the gap between the substrate 2 and the semiconductor chip 1 is large with respect to the warp between the semiconductor chip 1 and the semiconductor chip 1, as shown in FIG.
When the gap is small, the metal balls 6 are crushed as shown in FIG. 1B, the amount of the solder paste 5 protruding is small, and the connection with the adjacent bumps can be performed in a stable state without a bridge. Can be prevented. Further, since the height of the bump is high, the stress applied to the bump portion can be alleviated by being dispersed due to the difference in thermal expansion coefficient between the substrate 2 and the semiconductor chip 1, so that the thermal cycle life is extended. Further, since the gap between the substrate 2 and the semiconductor chip 1 is large, the sealing resin can be easily applied and the flux can be easily washed.

The material of the bumped bumps is copper,
Gold, solder, palladium, etc. can be used. As the material of the metal balls 6, gold, copper, gold-tin alloy, solder, plastic balls plated with nickel gold, or the like can be used. Instead of the solder paste 5, silver paste, silver palladium paste, gold paste or the like can be used.

[0026]

The semiconductor chip mounting method of the present invention has the effect that no special process is required to form bumps with protrusions on the semiconductor chip.

[Brief description of drawings]

1A and 1B are cross-sectional views for explaining one embodiment of the present invention.

2A and 2B are cross-sectional views showing a first conventional example.

3A to 3C are cross-sectional views showing a second conventional example.

FIG. 4 is a sectional view showing a third conventional example.

5A and 5B are cross-sectional views showing a fourth conventional example.

6A and 6B are cross-sectional views showing a fifth conventional example.

7 (a) to 7 (e) are cross-sectional views showing a method of forming the needle-like bent metal shown in FIGS. 6 (a) and 6 (b) in the order of steps.

8A to 8C are a cross-sectional view and a perspective view showing a sixth conventional example.

[Explanation of symbols]

 1 semiconductor chip 2 substrate 3 electrode pad 4 ball bump with protrusion 5 solder paste 6 metal ball 7 mounting pad

Claims (3)

(57) [Claims] 1. (A) A step of forming a bumped ball bump on an electrode pad provided on a semiconductor chip using a wire bonder, (B) a conductive paste on the upper surface of the bumped ball bump by a transfer method. And (C) attaching the conductive paste to the mounting pad provided on the substrate by screen printing, (D) mounting a metal ball on the conductive paste in (C). Process, (E)
Aligning the ball bumps with protrusions with the metal balls, and mounting the semiconductor chip on the substrate;
(F) A method of mounting a semiconductor chip, including the step of bonding the bumped ball bumps 4, the metal balls, and the mounting pads. 2. A semiconductor chip connection characterized in that a ball bump is formed on an electrode pad of a semiconductor chip, a conductive ball is sandwiched between a mounting pad of a substrate and the ball bump, and the conductive ball is bonded with a conductive paste. Construction. 3. The material of the bump ball bump is copper, gold, solder or palladium, and the material of the metal ball is gold, copper, gold-tin alloy, solder or plastic. 2. The method of mounting a semiconductor chip according to claim 1, wherein one of balls plated with nickel and gold is used, and as the conductive paste, one of silver paste, silver palladium paste, and gold paste is used.