JPS6199357A - Semiconductor device - Google Patents

Abstract

PURPOSE:To obtain a semiconductor device characterized by less internal stress, excellent moisture resistance and thermal shock resistance, and high reliability, by using a sealing resin provided with the stabilized reduction ability of thermal stress. CONSTITUTION:A monomer, which can yield a (metha) acrylic acid ester resin, whose glass transition temperature is less than a room temperature, and a monomer, which has two or more polymerizing vinyl groups is one molecule, are polymerized in an epoxy resin. A hardening agent, a filler and the like are added in said reacted product and kneaded. By using the resin composition, a required part to be sealed is sealed by transfer molding and the like. The fine particles of the (metha) acrylic acid ester resin, which is formed by the polymerization, form a bridging structure at an initial period by the monomer component having a the polymerizing vinyl group, when the epoxy resin is hardened in sealing. The particles are hooked by the bringing mesh structure accompanied by the hardening of the epoxy resin and fixed. Therefore, the thermal stress is absorbed and alleviated by the fine particles. Clouding due to the poor dispersion can be prevented. Thus the semiconductor device characterized by less internal stress and excellent moisture resistance and thermal shock resistance is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a semiconductor device with low internal stress and excellent moisture resistance and thermal shock resistance.

(Prior art) In general, sealing means for semiconductor devices are broadly classified into metal or ceramic sealing and resin sealing using thermosetting resin such as epoxy resin. Resin sealing has become mainstream, and resin sealing is now being used even in VLSI (very high density integrated circuits) such as memories and microcomputers.

However, due to technological innovation in the field of resistive conductors, the density of silica has increased, the device size has become larger, and wiring has become finer.As a result, packages have also become smaller and thinner. There is a demand for improved reliability, and in particular, the thermal stress generated between the element and the sealing material has a large effect on moisture resistance and thermal shock resistance, so reducing this thermal stress has become an issue.

Therefore, various attempts have been made to reduce the thermal stress of epoxy resins used as sealing materials, and at present, the mainstream method is to add rubber.

In other words, this method takes advantage of the fact that rubbers and epoxy resins are generally incompatible and disperses rubber particles in a continuous phase of epoxy resin, thereby maintaining the high heat resistance inherent to epoxy resins. The aim is to absorb and alleviate thermal stress using rubber particles.

However, as it is well known, general-purpose rubbers such as polybutadiene and isoprene undergo deterioration such as main chain scission when heated, so semiconductor devices sealed with epoxy resins containing particles of these rubbers require various heat treatments. There has been a problem in that the ability of the particles to absorb and relax thermal stress gradually decreases during the manufacturing process of semiconductor devices.

(Problems to be Solved by the Invention) The present invention aims to solve the above-mentioned conventional problem in which rubber particles added to an epoxy resin, which is a sealing resin, deteriorate and reduce its performance. By using a sealing resin with a stable ability to reduce thermal stress instead of adding rubber, we aim to provide highly reliable semiconductor devices with low internal stress and excellent moisture resistance and thermal shock resistance. The purpose is

(Means for Solving the Problems) 1 As a result of intensive studies for the above purpose, the inventors conducted a polymerization reaction of specific monomer components in an epoxy resin to produce (meth)acrylic acid ester. In a resin composition containing a reaction product that produces a epoxy resin, a (meth)acrylate ester resin that is incompatible with the epoxy resin is dispersed in the form of fine particles. When this resin composition is used as a sealing resin, thermal stress is absorbed and alleviated by the (meth)acrylic acid ester resin while retaining the high heat resistance inherent to epoxy resin. This invention was achieved by discovering that the performance does not deteriorate due to the addition of rubbers.

That is, in this invention, the glass transition temperature is below room temperature (
a monomer capable of producing a meth)acrylic acid ester resin;
The gist is a semiconductor device sealed with a resin composition whose main component is a reaction product obtained by polymerizing a monomer having 2 (V1 or more) polymerizable vinyl groups in one molecule in an epoxy resin. There is.

(Structure of the invention) Used for tRM of the resin composition used in this invention.
・The glass transition temperature is below room temperature, i.e. 25°
Generally used acrylic esters and methacrylic esters can be used as monomers that can form C or lower (meth)acrylic ester resins, and specific examples of these acrylic esters include those in which the alkyl group is a methyl group. , an ethyl group, an n-propyl group, a linear and branched butyl group, a 2-ethylhexyl group, and the like.

Furthermore, specific examples of methacrylic esters include straight and branched alkyl groups having 4 to 1.2 carbon atoms, such as butyl, isobutyl, hexyl, isohexyl, octyl, and dodecyl.

In addition to methacrylic acid alkyl esters having linear and branched side chains, methacrylic acid alkyl esters having linear and branched side chains, and 2-ethylhexyl methacrylate 1
, hydroxyethyl methacrylate and the like are preferred.

In addition, if necessary, two or more of the above monomers may be used in combination.

The glass transition temperature of the (meth)acrylic acid ester resin specified here is measured using a differential calorimeter, etc.
Refers to the known value for acrylic ester resin.

However, although these glass transition temperature values are normally measured for (meth)acrylic ester resins having an average degree of polymerization of at least 100, in the present invention, (meth)acrylic ester resins having an average degree of polymerization of 100 or less are used. It is also possible to use resin.

In this invention, when only methyl methacrylate, ethyl methacrylate, and propyl methacrylate are used, the glass transition temperature of the methacrylate ester resin produced is higher than room temperature. This is not preferred in the present invention because it does not reduce the thermal stress of the entire device.

However, as mentioned above, ethyl methacrylate and propyl methacrylate can also be used as long as the (meth)acrylic ester resin has an average degree of polymerization of 100 or less.

In addition, a monomer having two or more polymerizable vinyl groups in one molecule can form the above-mentioned (meth)acrylic acid ester resin when used alone. In comparison, it further enhances the effect of reducing thermal stress, significantly improves the moisture resistance and thermal shock resistance of semiconductor devices, and also has the function of preventing slight clouding of the resin after sealing when used alone. .

Although it is not clear why such a function is expressed, the (meta) produced by polymerization in epoxy resin
When the epoxy resin is cured when encapsulating a semiconductor device with the resin composition, the fine particles of the acrylic ester resin are initially cured by the monomer component having two or more polymerizable vinyl groups in one molecule. The crosslinked structure is entangled with the crosslinked network structure that accompanies the curing of the epoxy resin, allowing the fine particles to maintain a good dispersion without migrating to the surface, concentrating and unevenly distributing the particles, or fusion of particles with each other. It is assumed that the fine particles are immobilized in the epoxy resin, thereby maximizing the thermal stress absorption and relaxation effect of the fine particles, and also preventing the formation of hills due to poor dispersion.

Such monomers having two or more polymerizable vinyl groups in one molecule include divinylbenzene, monoethylene glycol dimethacrylate, diethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, and neopentyl glycol dimethacrylate. , trimethylolpropane trimethacrylate, 1.6 hexanediol dimethacrylate, bisphenol A dimethacrylate, diethylene glycol acrylate, tetraethylene glycol diacrylate, neopentyl glycol diacrylate, 1.5 bentanediol diacrylate, 1 diacrylate .6 hexanediol, trimethylolpropane triacrylate, and the like.

Such a heavy substance having two or more polymerizable vinyl groups in one molecule accounts for 0.5 to 100% of the total monomer components including monomers capable of forming the above-mentioned (meth)acrylic acid ester resin. 3
It is best to use it at a ratio of 2% by weight; if this amount is less than 0.5% by weight, the fine particles of the (meth)acrylic acid ester resin produced will be difficult to immobilize on the epoxy resin (and vice versa). If the amount exceeds 3% by weight, the entire resin composition becomes highly viscous, resulting in poor moldability.

In addition, the amount of the above two types of monomers used in the epoxy resin is 3 to 40 parts by weight of the (meth)acrylic acid ester resin formed by polymerization per 100 parts by weight of the epoxy resin.
Parts by weight, particularly preferably from 5 to 25 parts by weight.

The reason for this is that if the two types of monomers are less than 3 parts by weight of the (meth)acrylic acid ester resin formed by their polymerization relative to the epoxy resin that is the continuous phase, the effect of reducing thermal stress in semiconductor devices is insufficient. On the other hand, if the amount exceeds 40 parts by weight, the inherent heat resistance of the epoxy resin decreases, which is not preferable in the present invention.

As the polymerization initiator used in the polymerization of the above-mentioned monomers, various types conventionally used in the polymerization of (meth)acrylic acid ester resins can be used.

Specific examples include azo compounds such as azobisbutyronitrile, polymerization initiators that generate radicals upon heating such as peroxides such as lauroyl peroxide, ketones such as benzoin and dibenzyl ketone, and azobisbutyronitrile. Examples include polymerization initiators that generate radicals upon irradiation with ultraviolet rays, such as azo compounds such as cyanovaleric acid.

On the other hand, the epoxy resin contained as a continuous phase in the resin composition used in the present invention is not particularly limited, and conventional sealing resins for semiconductor devices such as cresol novolac type, phenol novolac type, and bisphenol A type are used. Various epoxy resins used as epoxy resins can be used.

However, in the present invention, it is preferable to use epoxy resins that have an internal point above room temperature and exhibit a solid state or a highly viscous state at room temperature among various epoxy resins that are commonly used as sealing resins for semiconductor devices.

Novolak type epoxy resin is usually epoxy 1
60-250. Those having a softening point of 50 to 130°C are used.

Further, the Talesol novolac type epoxy resin preferably has an epoxy equivalent of 180 to 210. Those having a softening point of 60 to 11°C are used.

As the curing agent for such an epoxy resin used in this invention, any of various known epoxy resin curing agents including acid anhydrides, phenols, and polyamides can be used, but preferably those having a hydroxyl equivalent of 70 to 70 are used. 150
Novolac resins (phenol novolac, talesol novolac, etc.) are used.

In addition, various curing accelerators known for use in epoxy resins can be used together with the curing agent, and particularly preferred examples include 2,4,6-dolydimethylaminomethylphenol and 2-methylimidazole.

Further, fillers such as quartz glass powder, silica stone powder, and talc, and other various additives may be added to the resin composition according to the present invention, if necessary.

To prepare the resin composition used in this invention 1
First, the epoxy resin, the monomer components, and a polymerization initiator are mixed, and the mixture is heated and stirred to polymerize the monomer components.

During this polymerization, the initially transparent system becomes cloudy as the reaction progresses, but this is due to the formation of fine particles of the (meth)acrylate resin in a dispersed state.

Next, a curing agent, filler, etc. are added to the obtained modified epoxy resin and kneaded to obtain a resin composition for encapsulating a semiconductor device.

By sealing the required sealing portions by transfer molding or the like using the thus obtained resin composition, various semiconductor devices of the present invention with extremely low internal stress and excellent moisture resistance and thermal shock resistance can be obtained. can get. - The sealing part of these semiconductor devices has no clouding in the resin (and has a good appearance).

(Examples) Hereinafter, examples of the present invention will be specifically described along with their effects, but the present invention is not limited to these examples.

Examples 1 to 7 Each component with the composition shown in Table 1 below was put into a 500 m j2 round bottom flask and stirred at 150°C for 6 hours to form fine particles of (meth)acrylic acid ester resin. A modified epoxy resin dispersed in an epoxy resin was obtained. Next, using this resin, each component was kneaded using a mixing roll machine at 100° C. for 10 minutes to obtain a sealing resin composition having the composition shown in Table 3 below.

A semiconductor device was encapsulated by transfer molding using this resin composition.

Comparative Examples 1 to 4 Modified epoxy resins were prepared in the same manner as in Examples 1 to 7 with the compositions shown in Table 2 below, and semiconductor devices were sealed in the same manner as in Examples 1 to 7.

Conventional Examples 1 and 2 The components shown in Table 4 below were kneaded for 10 minutes using a mixing roll machine, and the resulting resin composition was used to seal semiconductor devices in the same manner as in Examples 1 to 7. went.

In addition, as the epoxy resin shown in Table 1.2.4, a resin with an epoxy equivalent of 190 and a softening point of 80°C was used, and as a phenol resin, a resin with a phenol equivalent of 130 and a softening point of 80°C was used, and further as shown in Table 4. As the terminal carboxylic acid butadiene-acrylonitrile copolymer, a resin having a carboxyl molecular weight of 11,400 and a butadiene:acrylonitrile copolymerization ratio of 7:3 was used, respectively.

Next, the semiconductor devices obtained in the above-mentioned Examples, Comparative Examples, and Conventional Examples were tested for internal stress due to piezoresistance, flexural modulus, and reliability tests for 1000 hours using a pressure cooker (abbreviated as PCT), - 50℃ 730 minutes ~ 150℃
2000 temperature cycle tests up to 730 minutes) (T
CT (abbreviated as CT) was measured and evaluated.

The results and the glass transition points of the resin compositions used are shown in Table 5 below.

In addition, the (meth)acrylic acid ester ffi-mer used in Examples 1 to 7 has a glass transition temperature of room temperature or lower (meth)
being able to form an acrylic ester resin;
Furthermore, the glass transition temperature of the ethyl methacrylate resin formed from the methyl methacrylate monomer in Comparative Example 4 is higher than room temperature.

(Left below) 1st Table 1 Nu fat bait row 1 1
1 21 31 41 51 61 71
1 epoxy resin 1 100110011
00110011001 100110011 Butyl acrylate monomer 1 101251101- 1-
1 -1 -1j acrylate ethyl monomer 1
-1 -1- 1 51101 -1 -11 Meccrylic acid dodecyl/L4i form 1 -1 -1- 1- 1
-1 251 1011 Monoethylene methacrylate I
O, 0510, 4+-10, 11-10, 21-1
1 glycolytic monomer 1 1111111
1 11111i111 Tetraethylene methacrylate l -1-10,21-
1-1-10,21 [Glycol monomer 11
1i11111 divinylbenzene monomer 1 -1
-1 -1 -10.11 -1 -11 Benzoyl peroxide l 0.0510.111O,0510,03
10,0510,1110,051 sauce 〒・ (2) place: Weight (g) 2nd table I H-shaped nail row + 1
1 21 31 411 epoxy resin
1 1001100110011001,
1 1 Butyl acrylate monomer 1 51 -1 -1
-1 layer 1 methyl acrylate monomer 1 -1 251 -
1-11 Dodecyl methacrylate monomer 1-1-
1 101 -11 Methyl methacrylate single chapter 1
-1 -1- 11011 Old oxidation to 7 sole
I O,02i o,n l 0.0510.051
(R position 2M parts) 3rd Table 1 Component 1 parts by weight I1 modified epoxy resin +11011 phenolic resin
1 50 112 Methylimidazole 10.51 - 1 Stearic acid 10.511 Fused silica powder + 5001 4th Table 1 (sub) J I 1121 1 Epoxy resin + 1001 '10
011 terminal carboxylic acid butadiene-111 1 acrylonitrile copolymer 1 -1 1011 phenolic resin + 501 50112-methylimidazole 10.5 10.5 1 to 1 stearic acid 10.5 10.5 1
r-111-------------Masu 11→-111 Fused silica powder +500 1500 1 (Unit double weight system From the results in Table 5 above, the amount obtained in each Example according to this invention The semiconductor devices produced by the test have extremely low internal stress (the defective rate in the PCT test is almost 0, there is no cracking in the TCT test, and they have excellent moisture resistance and thermal shock resistance, and are highly reliable. it is obvious.

In addition, in Comparative Examples 1 to 3, clouding occurred in the sealing part, but
In each example, no clouding occurred and a good appearance was exhibited.

(Effects of the Invention) The semiconductor device according to the present invention uses a resin composition whose main component is a reaction product obtained by polymerizing monomer components in an epoxy resin to produce a (meth)acrylic acid ester resin. Since the sealed part has the high heat resistance of the epoxy resin, thermal stress is absorbed and alleviated by the fine particles of (meth)acrylic acid ester resin fixed in the epoxy resin. Therefore, it exhibits excellent moisture resistance and thermal shock resistance, and is highly reliable.

Claims (1)

[Claims] (1) A monomer that can form a (meth)acrylic acid ester resin whose glass transition temperature is below room temperature, and 2 monomers in one molecule.
1. A semiconductor device sealed with a resin composition whose main component is a reaction product obtained by polymerizing a monomer having one or more polymerizable vinyl groups in an epoxy resin.