JPH11340385A - Resin-sealed semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the matching of the adhesion and thermal expansion coefficient with a resin by making a metal member contacted or near to a semiconductor element, of Al containing specified vol. of hard inorganic grains. SOLUTION: In a resin seal type semiconductor device having a package structure sealed with a semiconductor element sealed with a resin, the main component of a metal member contacted or near to the semiconductor element is Al containing hard inorganic grains 10-30 vol.%, the hard inorganic grain is of one or more of SiC, Al2 O3 , AlN, BN, WC and SiN, and an alumite film is preferably formed on at least a part of the metal member surface whereby the thermal expansion coefficient difference between the metal member and general seal resin can be suppressed to about 3-4 ppm and the mechanical strength and Young's modulus can be improved, compared with an Al-made metal member.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device such as an IC or an LSI, and more particularly to a semiconductor device employing a resin-sealing type as a packaging structure.

[0002]

2. Description of the Related Art Normally, most of semiconductor devices made of Si, Ge, GaAs, etc. are used as one of package forms for mounting on a printed circuit board or the like, for example, wire bonding while being mounted on a lead frame. And then sealed with resin. This resin-encapsulated type has been increasingly used in semiconductor package structures because it is cheaper and superior to mass production as compared with the earlier metal-sealed and ceramic-sealed types.

For example, as a package in which a semiconductor element is mounted on a lead frame made of a Cu alloy or a NiFe alloy and sealed with an epoxy resin or the like, DIP (dual in-line package) and SOP (small outline package) are used.
Package), QFP (quad flat package) and the like.

In addition, a BGA (ball grid array) using a rigid resin circuit board, a flexible tape circuit board, a LOC (lead-on-chip) type lead frame, or the like, which is required to make the package smaller and higher in density. )
As such, OMPAC (overmold pad grid carrier), tape BGA, μBGA and the like are also used. MCM (multi-chip module) with multiple elements mounted on a substrate and sealed in one package
Are also prevalent in some areas.

[0005] On the other hand, as the integration and size of semiconductor elements increase, the required power of the semiconductor elements tends to increase, and the amount of heat generated tends to increase. In particular, in a resin-sealed type, the problem of heat radiation that suppresses a rise in temperature has attracted attention. Further, in recent years, there has been an increasing tendency to shift from a conventional ceramic package to a resin-encapsulated type in order to reduce costs.

Therefore, it is widely practiced to dispose a metal member made of Cu or Al having high thermal conductivity close to the semiconductor element as a heat radiating plate for a heat spreader, a heat sink or the like.

[0007]

In a conventional heat sink, a semiconductor element is often directly fixed on a metal plate with an adhesive or the like, and accordingly, the mechanical strength of the semiconductor package is reduced to the heat sink. There are many examples that depend on it. Therefore, there are increasing cases where a metal plate as a heat sink is expected to function as a substrate.

However, Cu metal members have poor adhesion to resin and are liable to be corroded and discolored. Therefore, the ends are stepped to obtain blackening treatment, Ni plating treatment, and mechanical fitting. Extra steps such as processing into a special shape such as are required.

Such a material made of Cu is excellent in thermal conductivity, but has a high specific gravity, and is not necessarily an optimum material. On the other hand, when alloying to increase mechanical strength, there is a problem that thermal conductivity is reduced.

[0010] On the other hand, Al is lightweight, and at the same time, can be easily subjected to an alumite treatment or a black coloring treatment, so that it is excellent in electrical insulation and adhesion to a resin.
However, since the coefficient of thermal expansion is as large as 22 to 25 ppm, and the mechanical strength and Young's modulus are small, there is a disadvantage that the occurrence of thermal distortion increases particularly as the size of the member increases, and that it is weak against mechanical stress.

As an improved example of Al, a semiconductor device using a composite material in which Al is impregnated in a SiC sintered body is disclosed in Japanese Patent Application Laid-Open No. 5-149663. It is a porous continuum in which SiC accounts for 50 to 75%, the coefficient of thermal expansion is excessively reduced to 5 to 8 ppm, and the difference from the coefficient of thermal expansion of a general sealing resin is large. Japanese Unexamined Patent Publication (Kokai) No. 61-7637 discloses a semiconductor device in which a composite material of SiC fiber and Al is used for the mounting portion of the semiconductor element. Is the coefficient of thermal expansion. In any case, the composite materials of these improved examples are manufactured by complicated processes, so that high costs cannot be avoided and are not suitable for practical use.

As described above, a metal member used as a heat sink or a substrate in a resin-sealed package of a semiconductor element is inexpensive and economical, but has a close bonding property with resin and a matching coefficient of thermal expansion. Although mechanical strength, proper Young's modulus, lightness, and the like are desired, a material that sufficiently satisfies all of them has not yet been obtained.

In view of the above problems, the present invention provides an inexpensive metal member which functions as a radiator plate or a substrate, and has an excellent bonding strength with resin, matching of thermal expansion coefficient, mechanical strength and proper Young's modulus. Another object of the present invention is to provide a high-quality resin-encapsulated semiconductor device that is lightweight and has no thermal distortion by providing a device having excellent characteristics of lightness.

[0014]

According to a first aspect of the present invention, there is provided a resin-sealed semiconductor device having a package structure in which a semiconductor element is sealed with a resin. In the apparatus, a metal member is provided in contact with or close to the semiconductor element, and the metal member is mainly composed of Al containing hard inorganic particles in a range of 10% by volume or more and 30% by volume or less. .

According to a second aspect of the present invention, in the resin-encapsulated semiconductor device according to the first aspect, the hard inorganic particles are made of SiC, Al ₂ O _3.
One or more of O ₃ , AlN, BN, WC, and SiN.

According to a third aspect of the present invention, there is provided the resin-sealed semiconductor device according to the first aspect, wherein at least a part of the surface of the metal member is provided with an alumite-treated coating. It has been formed.

According to a fourth aspect of the present invention, there is provided a resin-sealed semiconductor device according to the first aspect, wherein the metal member releases heat from a semiconductor element. It is arranged as.

According to the present invention, as a result of various studies by the present inventors,
A metal member made of Al containing hard inorganic particles with a content in a specific range has a coefficient of thermal expansion within a range where a difference from a coefficient of thermal expansion of a general sealing resin is about 3 to 4 ppm. The present invention has been found not only to be able to suppress, but also to be able to greatly improve the mechanical strength and the Young's modulus as compared with a mere Al-made metal member, leading to the present invention.

That is, by setting the hard inorganic particles contained in Al constituting the metal member to be in the range of 10% by volume or more and 30% by volume or less, first, the coefficient of thermal expansion of the member is set within the range of 14 to 20 ppm. Can be controlled. Within this range of the coefficient of thermal expansion, the difference from the coefficient of thermal expansion of a general sealing resin such as epoxy resin is 3 to 4 ppm.
It can be suppressed to a small difference. Therefore, thermal distortion generated in the resin sealing body is suppressed to be very small, and it is possible to cope with an increase in the size of the device.

Further, the metal member made of Al containing hard inorganic particles within the above specific range has a thermal conductivity of 1
100 to 200 W / mK, Young's modulus is 800 to 1
200 kg / mm ² and a mere Young's modulus of Al metal body of 68
The value is almost twice the value of 00 to 7000 Kg / mm ² , and the deformation can be suppressed to a small value with respect to mechanical and thermal stress.

The content of the hard inorganic particles is 30% by volume.
If it exceeds, the coefficient of thermal expansion tends to be excessively low, and conversely, the difference with the coefficient of thermal expansion of the sealing resin is not only widened, but also the properties of inorganic ceramics are excessively expressed, and machining and plastic processing are performed. It becomes difficult to perform alumite treatment, plating treatment, and the like, which will be described later, and furthermore, the electrical and thermal conductivity is reduced, which is not practically suitable. On the other hand, if it is less than 10% by volume, the effect of dispersing particles cannot be sufficiently obtained, and the above-mentioned characteristics are not improved.

Further, the metal member according to the present invention is economical because it is obtained by a manufacturing process similar to a normal metal manufacturing process, unlike the above-described composite which is a conventional Al-improved product. For example, it can be obtained by a simple process of extruding and rolling an ingot after solidifying hard inorganic particles in an Al melt while stirring and dispersing within the above content range.

As described above, in the metal member made of Al containing hard inorganic particles within the above-mentioned specific range according to the present invention, in addition to the excellent characteristics inherent in Al, such as light weight and thermal conductivity, Since the thermal expansion coefficient matching and the Young's modulus and strength are greatly improved, a lightweight resin-encapsulated semiconductor device having excellent heat dissipation and mechanical strength can be obtained at low cost by providing this metal member.

The hard inorganic particles in the present invention are:
For example, as described in claim 2, SiC, Al
One or a plurality are selected from ₂ O ₃ , AlN, BN, WC, and SiN. In particular, when SiC or Al ₂ O ₃ is used as the dispersed particles, the characteristic of suppressing the deformation due to the mechanical and thermal stresses can be more advantageously realized. Further, as the Al matrix, from the viewpoint of thermal conductivity and mechanical strength, 600
It is preferable to use a 0-series or 1000-series alloy.

Further, since the metal member is mainly composed of Al, the alumite treatment can be easily performed. Therefore, at least a part of the surface of the metal member is subjected to the alumite treatment. By forming an oxide film by the above, electrical insulation and better resin adhesion can be obtained.

The metal member according to the present invention not only has an effect of imparting mechanical strength to a semiconductor device package, but also has
If at least a part thereof is disposed in contact with or close to the semiconductor element in the sealing resin, the function as an excellent heat sink, that is, a heat spreader can be exhibited.

[0027]

DETAILED DESCRIPTION OF THE INVENTION (Embodiment 1) Hereinafter, a first embodiment of the present invention, a metal member made of Al alloy containing Al ₂ 0 ₃ and the hard inorganic particles in SiC, the heat radiating plate ( FIG. 1 is a schematic sectional view showing a resin-sealed QFP provided as a heat spreader) and a die pad.

First, a 28 mm × 28 mm, 0.55 mm thick Al alloy plate containing 12% Al ₂ O ₃ and 10% SiC in the 6061 alloy is subjected to black alumite treatment to make the surface thick. The heat spreader 1 on which the alumite oxide film 2 of about 15 μm is formed is obtained.

The heat spreader 1 is adhered to the back surface of a 208-pin copper alloy (0.150 mm thick: EFTEC64T) lead frame 3 via a polyimide thermoplastic adhesive tape 4. Further, the semiconductor element 5 is mounted on the surface of the heat spreader 1 exposed to the device hole of the lead frame 3 by die bonding via a paste material 6 instead of a die pad, and the wire 7 is bonded and wired.・
In the molding step, sealing was performed with an epoxy mold resin 9 to obtain a resin-sealed semiconductor device (QFP).

With respect to the resin-encapsulated semiconductor device obtained in the above steps, deformation due to a heating experiment was observed. At this time, as a comparative example having the same configuration as the conventional one, a 6061 alloy containing no hard inorganic particles was subjected to the same black alumite treatment as the heat spreader 1 of the present embodiment (Comparative Example 1).
−a) as a heat spreader, the same semiconductor element mounting and molding resin sealing as in the above embodiment, and a 5 μm thick Ni on a tough pitch Cu plate in place of Al
Observations were also made on the semiconductor device mounted and molded resin-sealed in the same manner as in the above-described embodiment using the film-formed one (Comparative Example 1-b).

That is, the semiconductor device according to the present embodiment (hereinafter referred to as Embodiment 1) and the resin-encapsulated semiconductor devices of Comparative Examples 1-a and 1-b were each heated under a heating condition of a reflow soldering furnace. After heating to ° C., the warpage of each semiconductor device surface was observed. In the semiconductor device according to the first embodiment, the warpage could not be observed below the observation limit value (0.01 mm). In addition, each of the thermal resistances when a rated current (7.5 W) was applied was 4 ° C./W, and there was no difference.

On the other hand, it was observed that the surface of the semiconductor device of Comparative Example 1-a was clearly curved toward the resin side (the side opposite to the heat spreader with respect to the lead frame). Also, in the semiconductor device of Comparative Example 1-b, no warpage of the surface was observed as in the present embodiment, but the weight was as heavy as 4.6 g, which was twice that of the semiconductor device according to the first embodiment. .

The difference in the results of the heating experiments of these semiconductor devices is considered to be due to the difference in the material properties of each heat spreader as shown in Table 1 below. That is, the thermal expansion coefficient of the heat spreader of Comparative Example 1-a is large, because the difference between the thermal expansion coefficient of the epoxy-based mold resin 9 and the thermal expansion coefficient of the lead frame 3 is large. The thermal strain that occurs during the process also increases.

[0034]

[Table 1]

However, the heat spreader 1 according to the first embodiment is lightweight, has a coefficient of thermal expansion very close to the coefficient of thermal expansion of the lead frame 3 and the molding resin 9, has the same thermal conductivity, and is inexpensive. And excellent properties such as good adhesion to resin. Therefore, by providing such a heat spreader 1, it is possible to provide a resin-encapsulated semiconductor device with higher quality than before.

(Embodiment 2) Next, as a second embodiment of the present invention, a resin member provided with a metal member made of an Al alloy containing hard inorganic particles of SiC as a heat sink (heat spreader) and a die pad is used. The stop QFP is shown in the schematic sectional view of FIG.

First, a 32 mm × 32 mm, 0.4 mm thick Al alloy plate containing 12% SiC in the 6063 alloy is subjected to black alumite treatment in the same manner as in the first embodiment, so that the thickness of the surface is increased. The heat spreader 11 on which the alumite oxide film 12 having a thickness of about 15 μm is obtained.

The heat spreader 11 is bonded to the back surface of the same copper alloy lead frame 13 as used in the first embodiment via a polyimide thermoplastic adhesive tape 14. Further, the heat spreader 11 exposed in the device hole of the lead frame 13 is used as a die pad, a semiconductor element 15 is bonded and mounted on the surface of the heat spreader 11 by die bonding via a polyimide adhesive 16, and a wire 17 is bonded and wired. Resin sealing was performed with resin 19 to obtain a resin-sealed semiconductor device.

Here, the heat spreader 11 has a function as a substrate for mounting the semiconductor element 15 and also functions as a liquid leakage preventing plate for the mold resin 19. Therefore,
The semiconductor element 15 side is easily sealed in a resin sealing step without using a mold by the liquid leakage preventing action of the heat spreader 11 and the dam polymer 18 disposed on the circumference corresponding to the outer circumference of the heat spreader 11 on the lead frame 13. can do.

The heat spreader 11 according to the second embodiment
Has a thermal expansion coefficient of 19.8 ppm and a thermal conductivity of 167 W / (m ·
K) and the coefficient of thermal expansion of the mold resin 19 is 16.8 ppm
As a result of conducting a heating experiment similar to that of the first embodiment, no warpage was observed in the semiconductor device, and the heat generated when a rated current (7.5 W) was passed. The resistance was as low as 3 ° C./W, and good heat dissipation was observed.

Embodiment 3 Next, as a third embodiment of the present invention, a resin member provided with a metal member made of an Al alloy containing hard inorganic particles of SiC as a heat sink (heat spreader) and a die pad is used. The stop QFP is shown in the schematic sectional view of FIG.

First, an Al having a size of 28 mm × 28 mm and a thickness of 0.45 mm made of a 6061 alloy containing 25% SiC was used.
By subjecting the alloy plate to a black alumite treatment, a heat spreader 21 having an alumite oxide film 22 having a thickness of about 5 μm on the surface is obtained.

This heat spreader 21 is bonded and fixed to the tip of the inner lead of the lead frame 23 similar to that used in the first embodiment from the back side via a polyimide-based thermoplastic adhesive tape 24. Further, the semiconductor element 25 is mounted on the surface of the heat spreader 21 exposed to the device hole of the lead frame 23 as a die pad by die bonding via an adhesive 26, and a wire 27 is bonded and wired. In the molding step, sealing was performed with an epoxy-based mold resin 29 to obtain a resin-sealed semiconductor device.

The heat spreader 21 according to the third embodiment
Has a thermal expansion coefficient of 16.7 ppm and a thermal conductivity of 196 W / (m ·
K), the Young's modulus is 118 KN / mm ² ,
Has a coefficient of thermal expansion close to 16.6 ppm, and as a result of conducting a heating experiment similar to that of the first embodiment, no warpage is observed in the semiconductor device, and the rated current (7.5
The heat resistance when flowing W) was as low as 3 ° C./W, and good heat dissipation was observed.

Here, as a comparative example, a semiconductor device was mounted using a QFP lead frame having the same size as that of the third embodiment having a die pad for mounting a semiconductor device without using a heat spreader. The thermal resistance was also measured for the one subjected to the same mold sealing as in Embodiment 3. As a result, the comparative example has a high value exceeding 8 ° C./W, and it is clear that according to the present embodiment including the heat spreader 21, the heat dissipation of the semiconductor device has been greatly improved.

Next (Embodiment 4), as a fourth embodiment of the present invention, Al containing _Al 2 _{0 3} hard inorganic particles
Heat dissipating plate (heat spreader)
FIG. 4 is a schematic cross-sectional view showing a plastic BGA using a two-layer circuit glass resin substrate provided as an example.

First, a 22 mm × 22 mm, 0.65 mm thick Al alloy plate containing 22% Al ₂ O ₃ in the 6061 alloy was subjected to black alumite treatment to form an alumite having a thickness of about 25 μm on the surface. The heat spreader 31 on which the oxide film 32 is formed is obtained.

The heat spreader 31 is adhered and fixed to a glass resin substrate 33 having the same size and having copper foil circuits 36 on both sides via an insulating adhesive 34. Further, substrate 3
A semiconductor element 35 is bonded and mounted on the surface of the heat spreader 31 exposed in the device hole 3 through an insulating adhesive 34, and after bonding and wiring of a wire 37, sealing is performed with a mold resin 39 using a dam polymer 38. went. Thereafter, the solder balls 30 as external terminals were mounted on the circuit 36.

The heat spreader 31 according to the fourth embodiment
Has a thermal expansion coefficient of 17.1 ppm and a thermal conductivity of 166 W / (m ·
K) and the Young's modulus were 112 KN / mm ² . As a result of the same heating experiment as in the first embodiment, no warpage was observed.

Here, as a comparative example, instead of an Al alloy plate, a Cu alloy plate (22 mm × 22 mm, thickness 0.45 mm) containing 0.3% Sn and 0.0025% P was subjected to the same black oxidation treatment. Embodiment 4 using a comparative heat spreader having an oxide film having a thickness of about 1 μm
Plastic BGA with two-layer circuit glass resin substrate as in
I got

The plastic BGA according to the comparative example
Shows that the heat spreader for comparison has the same thermal expansion coefficient, thermal conductivity, and Young's modulus as those of the heat spreader 31 according to the fourth embodiment, and no warpage was observed in the above heating experiment. The weight of the semiconductor device is 3.3 g.
The GA semiconductor device weighed 1.5 g and was 1.5 g or more.

From the above results, according to the fourth embodiment,
By using the heat spreader 31, which has the characteristics of lightweight of Al while having excellent coefficient of thermal expansion matching and mechanical properties, a high-quality and light-weight resin-encapsulated semiconductor device can be obtained. It is effective for use in products where properties are required.

Embodiment 5 Next, as a fifth embodiment of the present invention, a copper foil provided with a metal member made of an Al alloy containing hard inorganic particles of SiC and AiN as a heat spreader (heat spreader). FIG. 5 is a schematic cross-sectional view showing a tape BGA using a circuit-stretched polyimide film.

First, an 18 mm × 18 mm, 0.50 mm thick Al alloy plate containing 15% SiC and 5% AlN in the 6061 alloy was subjected to black alumite treatment to obtain a surface having a thickness of about 10 μm. The heat spreader 41 on which the alumite oxide film 42 is formed is obtained.
However, in the heat spreader 41, a portion corresponding to a device hole region of the substrate 43 to be bonded later is formed in a concave shape in advance.

The heat spreader 41 is set to a thickness of 18 μm.
A 25 μm-thick polyimide tape substrate 43 having an m-copper circuit 46 is bonded and fixed via an insulating adhesive 44. Further, the semiconductor element 45 is bonded and mounted on the surface of the heat spreader 41 on the concave portion exposed in the device hole of the substrate 43 via the insulating adhesive 44, and the wire 47 is bonded and wired. went. At this time, the concave portion of the heat spreader 41 exerts the function of the dam polymer, and liquid leakage can be easily prevented without disposing the dam polymer. After this resin sealing, solder balls 40 as external terminals were mounted on the circuit 46.

The heat spreader 41 according to the fifth embodiment.
Has a thermal expansion coefficient of 17.0 ppm and a thermal conductivity of 189 W / (m ·
K) and the Young's modulus were 108 KN / mm ² . The heat spreader 41 has a function of dissipating heat generated by the semiconductor element 45 and also reinforces the flexible tape substrate 43,
It also has a function of a stiffener for providing rigidity to the resin-sealed semiconductor device.

Conventionally, a SUS plate is generally used for the stiffener. However, the thermal conductivity of this SUS plate is very small, about 1/15 of the thermal conductivity of the heat spreader 41 according to the fifth embodiment. Heat dissipation was insufficient.
Therefore, a two-layer stiffener combining Cu and SUS has been used particularly in a high-density high-speed semiconductor element requiring heat radiation.

On the other hand, according to the fifth embodiment, the excellent heat dissipation and the substrate reinforcing function can be easily realized by a simple configuration in which the semiconductor element 45 is mounted on the lighter heat spreader 41. can do.

[0059]

As described above, according to the present invention,
Inexpensive metal parts that exhibit excellent functions as heat sinks and substrates, as well as excellent adhesion properties with resin, thermal expansion coefficient matching, mechanical strength, proper Young's modulus, and lightweight properties Since the semiconductor device is provided, there is an effect that it is possible to provide a resin-sealed semiconductor device which is lighter in quality but higher in quality than the conventional one.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a resin-encapsulated semiconductor device (QFP) according to a first embodiment of the present invention.

FIG. 2 is a schematic sectional view of a resin-encapsulated semiconductor device (QFP) according to a second embodiment of the present invention.

FIG. 3 is a schematic sectional view of a resin-encapsulated semiconductor device (QFP) according to a third embodiment of the present invention.

FIG. 4 is a schematic sectional view of a resin-encapsulated semiconductor device (BGA) according to a fourth embodiment of the present invention.

FIG. 5 is a schematic sectional view of a resin-sealed semiconductor device (BGA) according to a fifth embodiment of the present invention.

[Explanation of symbols]

 1, 11, 21, 31, 41: heat spreader 2, 12, 22, 32, 42: alumite oxide film 3, 13, 23: lead frame 33: glass resin substrate 43: polyimide tape substrate 36, 46: copper foil circuit 4 , 14, 24: Polyimide thermoplastic adhesive tape 34, 44: Insulating adhesive 5, 15, 25, 35, 45: Semiconductor element 6: Paste material 16, 26: Polyimide adhesive 7, 17, 27, 37, 47: Wire 18, 38: Dam polymer 9, 19, 29, 39, 49: Epoxy mold resin 30, 40: Solder ball

Claims (4)

[Claims] 1. A resin-encapsulated semiconductor device having a package structure in which a semiconductor element is sealed with a resin, comprising: a metal member that is in contact with or close to the semiconductor element, wherein the metal member is 10% by volume or more and 30% by volume. A resin-encapsulated semiconductor device comprising, as a main component, Al containing hard inorganic particles within the following range. 2. The hard inorganic particles are made of SiC, Al ₂ O
_3. The resin-encapsulated semiconductor device according to claim 1, wherein the semiconductor device is at least one of AlN, BN, WC, and SiN. 3. The resin-encapsulated semiconductor device according to claim 1, wherein an alumite-treated film is formed on at least a part of the surface of the metal member. 4. The resin-encapsulated semiconductor device according to claim 1, wherein the metal member is disposed as a heat spreader for releasing heat from the semiconductor element.