JP2000323624A - Semiconductor device and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a semiconductor device in which an underfill resin can be prevented from peeling off by reducing warping of an insulating substrate when the underfill resin between a semiconductor chip and the insulating substrate is cured, and a manufacturing method thereof. SOLUTION: In a semiconductor device in which a semiconductor chip 12 is flip-chip mounted on a resin substrate 11 through a underfill resin 19, the length of a fillet 20 formed on the side edge face of the semiconductor chip 12 by implanting the underfill resin 19 is made longer than the distance between the surface of the resin substrate 11 and the rear side of the semiconductor chip 12. By doing this, when the underfill resin 9 between the semiconductor chip 12 and an insulating substrate is cured, warping of the insulating substrate can be reduced. Thus, the underfill resin 19 can be prevented from peeling off, and further, the resin substrate 11 can be protected against cracking.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a semiconductor device and a method of manufacturing the same, and more particularly, to a semiconductor device in which a semiconductor chip is flip-chip mounted on a printed wiring board and a method of manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, printed wiring boards (printed
A semiconductor device in which a semiconductor chip is flip-chip mounted on a d wiring board (PWB) is known.

FIG. 7 is a sectional view of a conventional semiconductor device. As shown in FIG. 7, the semiconductor device 1 is a flip chip having solder bumps 3 on an insulating substrate (PWB) 2 made of a resin such as polyimide, to which a reinforcing material made of copper (Cu) is attached. 4 is mounted face down. The flip chip 4 and the insulating substrate 2 are electrically connected by melting and connecting the solder bumps 3 and the preliminary solder of the insulating substrate 2.

Here, the flip chip 4 and the insulating substrate 2
Is 120μm and the pitch between bumps is 240μ
m, number of bumps is 3000, chip size is 13mm
□, the chip thickness is 0.68 mm.

In manufacturing the semiconductor device 1, an epoxy resin is injected into the solder connection between the insulating substrate 2 and the flip chip 4 in an appropriate amount as an underfill resin 5. , Proper temperature,
For example, it is cured at 150 ° C. By the curing, a fillet 5a, which is a protruding portion of the underfill resin 5, is formed from the side of the flip chip 4 onto the insulating substrate 2.

After the underfill resin 5 is injected, a silver (Ag) paste having a conductive property is applied to the back surface of the flip chip 4 as an adhesive resin 6a. At this time, the adhesive resin 6b is also applied to the upper portions of the reinforcing plates 7 arranged on both sides of the insulating substrate 2. Thereafter, a lid 8 made of Cu is arranged on the back surface of the flip chip 4 and on the reinforcing plate 7, and the lids 8 are fixed by curing the adhesive resins 6a and 6b.

After the lid 8 is attached, the flip-chip type BGA is mounted by mounting solder balls 9 on the back surface of the insulating substrate 2 on which the flip chip 4 is not mounted.
(Ball grid array) The semiconductor device 1 composed of a package is obtained.

[0008]

However, when a reliability test such as a temperature cycle test is performed on the semiconductor device 1, the warpage of the insulating substrate 2 serving as an interposer causes a problem between the flip chip 4 and the insulating substrate 2. Of the underfill resin 5 is stressed, and the underfill resin 5 is easily peeled off.

The stress applied to the underfill resin 5 easily causes a crack c (see FIG. 7) from the fillet 5a toward the inside of the insulating substrate 2.

[0010] If there is such peeling or crack c, an abnormality such as disconnection due to an open defect occurs. The peeling rate is about 10% after 300 cycles of the temperature cycle test.
(5/53).

The peeling of the underfill resin 5 occurs when the fillet 5a of the underfill resin 5 formed on the side surface of the chip is shorter than the chip thickness and the fillet 5a is located immediately below the chip. is there. In this case, when the underfill resin 5 is cured, a large stress is applied to the flip chip 4 and the insulating substrate 2 due to a difference in thermal expansion coefficient, and the flip chip 4 and the insulating substrate 2 are greatly warped.

In particular, at present, high-density wiring using a resin substrate having flexibility has become mainstream in semiconductor chips, and a conventional glass substrate lacking in flexibility cannot cope with high-density wiring. Therefore, it is inevitable to deal with the stress caused by thermal expansion.

An object of the present invention is to provide a semiconductor device capable of preventing the insulating substrate from warping when the underfill resin between the semiconductor chip and the insulating substrate is cured, and preventing the underfill resin from peeling off. It is an object of the present invention to provide a manufacturing method thereof.

[0014]

To achieve the above object, a semiconductor device according to the present invention is a semiconductor device in which a semiconductor chip is flip-chip mounted on a substrate via an underfill resin. The length of the fillet formed on the side end surface of the semiconductor chip by the implantation of the semiconductor chip is longer than the distance from the front surface of the substrate to the back surface of the semiconductor chip.

[0015] With the above configuration, on the substrate,
In a semiconductor device in which a semiconductor chip is flip-chip mounted via an underfill resin, a fillet formed on a side end surface of the semiconductor chip by injecting the underfill resin has a length from the surface of the substrate to the length of the semiconductor chip. It is longer than the distance to the back. This allows
When the underfill resin between the semiconductor chip and the insulating substrate is cured, the insulating substrate can be prevented from warping, and peeling of the underfill resin can be prevented.

Further, the semiconductor device can be manufactured by the method of manufacturing a semiconductor device according to the present invention.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. (First Embodiment) FIG. 1 is a sectional view showing a configuration of a semiconductor device according to a first embodiment of the present invention. FIG.
As shown in FIG. 1, the semiconductor device 10 has a layered structure in which an insulating resin substrate (PWB) 11 made of, for example, polyimide, a semiconductor chip 12 made of a flip-chip method, and a lid 13 made of Cu are stacked from the bottom in the stated order. At the periphery of the resin substrate 11, a metal reinforcing frame 14 sandwiched between the lid 13 is provided so as to surround the semiconductor chip 12 at the center.

The resin substrate 11 and the reinforcing frame 14 are made of an adhesive resin 15.
Thereby, the semiconductor chip 12 and the lid 13 are bonded to the adhesive resin 16.
Thus, the lid 13 and the reinforcing frame 14 are bonded to each other by the adhesive resin 17. These adhesive resins 15, 1
For 6, 17, for example, an Ag paste made of a silicone-based, epoxy-based, or thermoplastic resin is used.

A reinforcing plate made of Cu is attached to the resin substrate 11, and a semiconductor chip 12 having solder bumps 18 is mounted face down on the resin substrate 11. By mounting, the solder bumps 18 of the semiconductor chip 12 and the preliminary solder of the resin substrate 11 are melt-connected, and the semiconductor chip 12 and the resin substrate 11 are electrically connected.

Between the semiconductor chip 12 and the resin substrate 11,
An appropriate amount of epoxy resin is injected as an underfill resin 19 into the solder connection portion with the solder bump 18 interposed therebetween. By injecting the underfill resin 19, a fillet 20 which is a protruding portion of the underfill resin 19 is formed on the side surface of the semiconductor chip 12. The fillet 20 has an upper corner portion 20 a having a vertical cross section at which the upper surface and the side end surface of the semiconductor chip 12 intersect, and a lower corner portion 20 b which is a tip portion moving away from the semiconductor chip 12 along the resin substrate 11.
And has a substantially right-angled triangular shape with the line connecting to the oblique sides (see FIG. 1).

The amount of the underfill resin 19 to be injected is determined from the side end surface of the semiconductor chip 12 to the lower corner 20 of the fillet 20.
The fillet length L, which is the distance to b, is adjusted so as to be longer than the chip height H1, which is the distance from the front surface of the resin substrate 11 to the back surface of the semiconductor chip 12.

Here, the chip height H1 is the thickness of the semiconductor chip 12 plus the thickness of the solder bump 18, that is, the gap between the semiconductor chip 12 and the resin substrate 11. Further, instead of the chip height H1, a chip height H2 which is a distance from the surface of the resin substrate 11 before deformation due to warpage or the like to the back surface of the semiconductor chip 12 after deformation may be used. In this case, the fillet length L is equal to the tip height H2.
The adjustment is made to be longer than that, and the adjustment according to the degree of deformation of the resin substrate 11 becomes possible.

The thermal expansion coefficient α (ppm / ppm) of the resin substrate 11, the semiconductor chip 12, and the underfill resin 19
C) is as follows as an example. The resin substrate 11 is α
= 18, α = 3 for the semiconductor chip 12 and α = 20 to 32 for the underfill resin 19. The viscosity of the underfill resin 19 is 13 to 40 (Pa · s).

On the lower surface of the resin substrate 11 where the semiconductor chip 12 is not mounted, a plurality of solder balls 21 are provided over the entire lower surface.

In this semiconductor device 10, for example, the gap between the semiconductor chip 12 and the resin substrate 11 is 120 μm, the pitch between bumps is 240 μm, the number of bumps is 3000, the chip size is 13 mm □, and the chip thickness is 0.68 mm. Each is formed.

FIG. 2 is a process chart showing a method of manufacturing the semiconductor device of FIG. As shown in FIG. 2, first, a rectangular resin substrate 11 is prepared (see (a)).

On the resin substrate 11, a plurality of pads 22 are previously arranged on one surface, and external electrodes 23 are arranged on the other surface. The pad 22 and the external electrode 23 are
Those corresponding to each other are electrically connected to each other via an inner wiring layer (not shown).

Around the edge of the resin substrate 11, a reinforcing frame 14 for fixing the lid 13 later is provided with an adhesive resin 15.
Are pre-bonded. The reinforcing frame 14 also has a function of securing a space for installing the semiconductor chip 12 between the resin substrate 11 and the lid 13.

Next, the positions of the solder bumps 18 and the corresponding pads 22 are adjusted, and then the semiconductor chip 12 is mounted face down on the resin substrate 11 (see (b)). After mounting, the semiconductor chip 12 is mounted on the resin substrate 11 by melting the solder bumps 18 and connecting to the external electrodes 22 by reflow, so-called flip-chip mounting is performed (see (c)). Thereafter, flux cleaning is performed.

Next, in order to prevent the solder bumps 18 from peeling, a fluid underfill resin 19 is injected into the solder connection portion in the gap between the semiconductor chip 12 and the resin substrate 11 and applied onto the substrate 11 (( d)). Since the space between the semiconductor chip 12 and the resin substrate 11 is very small, the injected underfill resin 19 spreads over the entire surface of the semiconductor chip 12 by a capillary phenomenon.

At this time, the fillet length L of the fillet 20 is set to, for example, 1 to 1.5 mm so as to be longer than the chip height H1 which is the distance from the front surface of the resin substrate 11 to the back surface of the semiconductor chip 12. , Underfill resin 1
The injection amount of 9 is adjusted. In this case, the tip height H1
(120 μm + 0.68 mm = 0.8 mm), the fillet length L is adjusted to about 1 mm.

Thereafter, the underfill resin 19 is cured (heat-treated) at an appropriate temperature, for example, 150 ° C. and cured.

The chip connecting surface portion of the resin substrate 11 located immediately below the semiconductor chip 12 is in a state of being deformed into a mountain shape having a maximum warpage of about 60 μm.

Next, the lower surface of the semiconductor chip 12 mounted on the resin substrate 11 (the surface opposite to the surface on which the active element is formed) and the upper surface of the reinforcing frame 14 are bonded with a silicone-based low-elasticity Ag paste. Resins 16 and 17 are applied respectively,
The lid 1 covers the semiconductor chip 12 and the reinforcing frame 14.
After placing 3, cure the entire package ((e)
reference). The curing of the adhesive resins 16 and 17 causes the lid 13
Is fixed in the mounted state.

Thereafter, solder balls 21 are mounted on the back surface of the resin substrate 11 on which the semiconductor chip 12 is not mounted,
The semiconductor device 10 including the flip chip type BGA package is obtained.

That is, by making the fillet length L of the underfill resin 19 formed on the side surface of the semiconductor chip 12 longer than the chip height H1 (or the chip height H2), the semiconductor chip 12 and the resin substrate 11 are formed. It is possible to prevent the underfill resin 19 injected between them from peeling off. Also, by preventing peeling, the fillet 2
The crack c entering the resin substrate 11 from the lower corner portion 20b, which is the front end portion of the zero, can be prevented.

The peeling rate of the semiconductor chip 12 after 300 cycles in the temperature cycle test is as follows:
It was 0% (0/97). This is because the fillet length L is made longer than the chip height H1 so that the underfill resin 1 applied to the semiconductor chip 12 and the resin substrate 11 is removed.
This is because the stress of No. 9 can be reduced (dispersed).

After the injection of the underfill resin 19,
Adhesive resins 16 and 17 are applied to the back surface of the semiconductor chip 12 and the upper surface of the reinforcing frame 14, respectively.
9, the underfill resin 19 and the adhesive resins 15, 16,
17 may be cured simultaneously.

As a result, although a stress is generated when the resin applied to each part is cured, the stress is simultaneously generated by curing the resin at the same time, thereby canceling the stress, and the resin substrate 11 and the semiconductor chip 12 are locally localized. No stress is applied. (Second Embodiment) FIG. 3 is a sectional view showing a schematic configuration of a semiconductor device according to a second embodiment of the present invention.
As shown in FIG. 3, the semiconductor device 25 includes a semiconductor chip 1
The underfill resin 19 injected into the solder connection portion in the gap between the resin substrate 11 and the resin substrate 11 is cured using a mold (not shown) so that the fillet 26 has a rectangular vertical section instead of a substantially right triangle. Formed. Other configurations and operations are the same as those of the semiconductor device 10 (see FIG. 1).

Accordingly, the fillet 26 is integrally formed in a wall shape surrounding the semiconductor chip 12, and has a chip height H 1 from the front surface of the resin substrate 11 to the back surface of the semiconductor chip 12.
(Or fillet length L longer than tip height H2)
(About 1 mm). (Third Embodiment) FIG. 4 is a sectional view showing a configuration of a semiconductor device according to a third embodiment of the present invention. FIG.
Indicates a fillet formed in the semiconductor device of FIG. 4,
(A) is a plan view of a first example, and (b) is a plan view of a second example.

As shown in FIG. 4, in the semiconductor device 30, the chip connecting surface portion of the resin substrate 11 located directly below the semiconductor chip 12 is made hollow (see FIG. 4), or the underfill having a low thermal expansion coefficient is formed. The resin is injected and has a fillet 31 made of a high-viscosity resin. Other configurations and operations are the same as those of the semiconductor device 10 (see FIG. 1).

In this case, as shown in FIG. 5, the fillet 31 is formed only at the four corners except for the four sides of the semiconductor chip 12 (see FIG. 5A).
It is formed only on four sides except for the four corners 2 (see (b)). The fillet length L may be arbitrarily set, but it is more effective if the fillet length L is longer than the tip height H1 (or the tip height H2).

That is, there is no underfill resin which generates stress upon curing in the chip connecting surface portion of the resin substrate 11 located immediately below the semiconductor chip 12 or
Even if it is an underfill resin having a low coefficient of thermal expansion, no stress is generated between the resin substrate 11 and the semiconductor chip 12, and even if it is slight, warpage or the like due to the stress is hardly generated. No effect.

The thermal expansion coefficient α (ppm / ° C.) of the fillet 31 and the underfill resin when injected is as follows, for example. The high-viscosity resin of the fillet 31 has α = 10, the viscosity = 100 (Pa · s), and the underfill resin has α = 7 to 10.

FIG. 6 is a cross-sectional view showing a fillet formation state of the semiconductor device of FIG. As shown in FIG. 6, the resin supply nozzle 32 is located above the side end surface of the semiconductor chip 12 so as to be vertically movable along the side end surface of the semiconductor chip 12.
Then, a high-viscosity resin is dropped at four corners or four sides on the side of the solder connection portion to form a fillet 31.

When an underfill resin having a low coefficient of thermal expansion is injected into the solder connection between the resin substrate 11 and the semiconductor chip 12, a fillet 31 made of a high-viscosity resin is used.
May be performed from the air vent hole.

As described above, according to the present invention, in the flip-chip type BGA semiconductor device 10, the resin substrate 1
In order to prevent chip peeling or the like from occurring due to the warpage of 1, the underfill resin 19 as a reinforcing resin injected into the solder connection portion between the resin substrate 11 and the semiconductor chip 12 protrudes from the side surface of the semiconductor chip 12. The fillet, which is a part, was adjusted to a tip height or higher.

As a result, stress acting between a plurality of resins having different thermal expansion coefficients can be dispersed, and the semiconductor chip 1
When the underfill resin 19 between the substrate 2 and the resin substrate 11 is cured, the resin substrate 11 is prevented from warping, thereby preventing the underfill resin 19 from peeling and preventing the resin substrate 11 from being cracked. Can be.

Therefore, there is no occurrence of peeling or distortion as shown in the conventional example, and the productivity and reliability of the semiconductor device having the solder bump structure can be improved.

This is particularly effective in a semiconductor chip 12 of high-density wiring using a resin substrate 11 having flexibility, which is now mainstream. That is, in the semiconductor chip 12 of high-density wiring using the resin substrate 11, the number of terminals is about 3,000 pins to 5,000 pins, but in the case of a liquid crystal driver made of a glass substrate, it is about 40 to 50 pins. In addition, the chip size is about 13 to 17 mm square in the case of the semiconductor chip 12, but is about 9 mm square in the case of the liquid crystal driver, and the stress is proportional to the area ratio. is there.

The semiconductor device 30 includes the semiconductor chip 1
The chip connecting surface portion of the resin substrate 11 located directly below the resin substrate 2 is made hollow (see FIG. 4), or an underfill resin having a low coefficient of thermal expansion is injected, and a fillet 31 made of a high-viscosity resin is provided. Thereby, the resin substrate 1
The chip connection surface portion 1 does not have an underfill resin that generates stress upon curing, or even has a low thermal expansion coefficient. Has no effect.

In each of the above embodiments, the BGA
The structure is not limited to a CSP (chip size).
The same can be applied to a semiconductor device having a (package) structure.

[0053]

As described above, according to the present invention, in a semiconductor device in which a semiconductor chip is flip-chip mounted on a substrate via an underfill resin, the semiconductor chip is injected by the underfill resin. The length of the fillet formed on the side end surface is longer than the distance from the front surface of the substrate to the back surface of the semiconductor chip, so that when the underfill resin between the semiconductor chip and the insulating substrate is hardened, the insulating property is increased. It is possible to reduce the warpage of the substrate, prevent the underfill resin from peeling off, and prevent the resin substrate from cracking. Therefore, the productivity and reliability of the semiconductor device having the solder bump structure can be improved.

The above-described semiconductor device can be manufactured by the method for manufacturing a semiconductor device according to the present invention.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a configuration of a semiconductor device according to a first embodiment of the present invention.

FIG. 2 is a process chart showing a method for manufacturing the semiconductor device of FIG. 1;

FIG. 3 is a sectional view illustrating a schematic configuration of a semiconductor device according to a second embodiment of the present invention;

FIG. 4 is a sectional view showing a configuration of a semiconductor device according to a third embodiment of the present invention.

5A and 5B show a fillet formed in the semiconductor device of FIG. 4, wherein FIG. 5A is a plan view of a first example and FIG. 5B is a plan view of a second example.

FIG. 6 is a cross-sectional view showing a fillet formation state of the semiconductor device of FIG. 4;

FIG. 7 is a sectional view of a conventional semiconductor device.

[Explanation of symbols]

 10, 25, 30 Semiconductor device 11 Resin substrate 12 Semiconductor chip 13 Lid 14 Reinforcement frame 15, 16, 17 Adhesive resin 18 Solder bump 19 Underfill resin 20, 26, 31 Fillet 20a Upper corner 20b Lower corner 21 Solder ball 22 Pad 23 External electrode 32 Resin supply nozzle H1, H2 Tip height L Fillet length

Claims (9)

[Claims] 1. A semiconductor device in which a semiconductor chip is flip-chip mounted on a substrate via an underfill resin, wherein a length of a fillet formed on a side end surface of the semiconductor chip by injection of the underfill resin is: A semiconductor device, wherein the distance is longer than a distance from a front surface of the substrate to a back surface of the semiconductor chip. 2. The semiconductor device according to claim 1, wherein said substrate is a resin substrate. 3. The semiconductor device according to claim 1, wherein the substrate and the semiconductor chip are connected via solder bumps, and a back surface of the semiconductor chip has a lid bonded with an upper surface of a reinforcing frame surrounding the semiconductor chip with an adhesive resin. The semiconductor device according to claim 2, wherein: 4. The semiconductor device according to claim 2, wherein the underfill resin is cured by using a mold and integrally molded into a wall shape surrounding the semiconductor chip. 5. The thermal expansion coefficient of the underfill resin,
5. The semiconductor device according to claim 2, wherein the thermal expansion coefficient is set to an intermediate value between the thermal expansion coefficient of the substrate and the thermal expansion coefficient of the semiconductor chip. 6. The semiconductor device according to claim 2, wherein the underfill resin is removed from a portion of the substrate connected to the semiconductor chip, and the fillet is formed only around the semiconductor chip. 13. The semiconductor device according to claim 1. 7. The semiconductor device according to claim 6, wherein an underfill resin having a low coefficient of thermal expansion is injected into a portion where said underfill resin is removed. 8. A step of flip-chip mounting a semiconductor chip on a substrate; a step of performing reflow to connect the substrate and the semiconductor chip by bumps; By adjusting the amount of resin so that the length of the fillet formed on the side surface of the semiconductor chip by applying the fill resin is longer than the distance from the front surface of the substrate to the back surface of the semiconductor chip, the underfill resin is removed. A method for manufacturing a semiconductor device, comprising: a step of applying; and a step of curing the applied underfill resin. 9. The method according to claim 8, wherein, in the step of applying the underfill resin, the fillet is formed only on the periphery of the semiconductor chip except for a portion of the substrate connected to the semiconductor chip. The manufacturing method of the semiconductor device described in the above.