JPS6199358A - 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 stabilized reduction ability of thermal stress. CONSTITUTION:A monomer, which can form a (metha) acrylic acid ester resin, whose glass transition temperature is less than a room temperature, and a monomer having an epoxy group 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. Then the epoxy group is included in the fine particles of the (metha) acrylic acid ester resin, which is formed by the polymerization. Therefore, the epoxy group of the fine particles are reacted at the same time the epoxy resin is hardened and fixed when the sealing of a semiconductor device is performed by the resin composition. Then the thermal stress is absorbed and alleviated by the fine particles, and the clouding due to poor dispersion can be prevented. Thus the semiconductor device characterized by less internal stress and excellent moisture resistance and thermal shock resistance can be 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,
Technological innovations in the semiconductor field have led to increased integration, larger device sizes, and finer wiring, and packages are also becoming smaller and thinner. Improvements are desired, especially since thermal stress generated between the element and the sealing material has a large impact on moisture resistance and thermal shock resistance.

The challenge is to reduce thermal stress.

Therefore, various attempts have been made to reduce the thermal stress of epoxy resins used in sealing materials, and at present, the mainstream method is the addition of 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) As a result of intensive studies for the above purpose, the inventors have developed a (meth)acrylic acid ester resin by polymerizing a specific monomer component in an epoxy resin. 1. In the resin composition containing the generated reaction product, the (meth)acrylic acid ester resin which is incompatible with the epoxy resin is dispersed in the form of fine particles, and is immobilized in the epoxy resin. When this resin composition is used as a sealing resin, thermal stress is absorbed and alleviated by the above (meth)acrylic acid ester resin while retaining the high heat resistance inherent to epoxy resin, and it is also comparable to conventional rubbers. The present invention was completed based on the discovery that there is no decrease in performance due to deterioration as occurs when adding .

In other words, this invention combines a monomer capable of forming a (meth)acrylic acid ester resin with a glass transition temperature below room temperature and a monomer having an epoxy group into an epoxy resin with 11
The gist of the present invention is a semiconductor device sealed with a resin composition containing a reaction product obtained by a single reaction.

(Structure of the Invention) Monomers that form the (meth)acrylic acid ester resin with a glass transition temperature of room temperature or lower, that is, 25°C or lower, used in the preparation of the resin composition used in the present invention are generally used for general purposes. Acrylic acid esters and methacrylic esters are used.

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

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

Preferred examples of this acrylic ester include acrylic alkyl esters in which the alkyl group is a methyl group, an ethyl group, an n-propyl group, a linear or branched butyl group, a 2-ethylhexyl group, etc. It is mentioned as. Specific examples of methacrylic acid esters include straight and branched alkyl groups having 4 to 12 carbon atoms, such as butyl, isobutyl, hexyl, isohexyl, octyl, dodecyl, octadecyl, etc. In addition to certain methacrylic acid alkyl esters,
Preferred examples include octadecyl methacrylate, 2-ethylhexyl methacrylate, and hydroxyethyl methacrylate, which have linear or branched side chains.

If necessary, two or more of these monomers may be used in combination.

, However, as mentioned above, if the average degree of polymerization is 100 or less (
As for meth)acrylic acid ester resins, ethyl methacrylate and propyl methacrylate can also be used.

Note that methyl methacrylate, ethyl methacrylate, and propyl methacrylate are not preferred because the glass transition temperature of the methacrylate resin produced will be higher than room temperature if only these are used. Acid ester resins are not preferred in this invention because they do not reduce the thermal stress of the entire semiconductor device.

In addition, the monomer having an epoxy group includes diglycidyl methacrylate, glycidyl acrylate, etc., and by using this, the monomer that can form the above-mentioned (meth)acrylic acid ester resin can be used alone. It further enhances the effect of reducing thermal stress compared to the case where it is used, significantly improves the moisture resistance and thermal shock resistance of semiconductor devices, and also prevents the slight clouding that occurs in the resin after sealing when used alone. It has the following.

The reason why such a function is expressed is not clear, but it is produced by polymerization in epoxy resin.

Since the fine particles of the (meth)acrylic acid ester resin thus formed contain epoxy groups, when a semiconductor device is encapsulated with a resin composition whose main component is a modified epoxy resin containing these fine particles, the epoxy resin At the same time as curing, the epoxy groups of the fine particles also react, and as a result, the fine particles are fixed in the epoxy resin in a well-dispersed state without migrating to the surface or becoming concentrated and unevenly distributed. It is presumed that stress absorption and relaxation effects are maximized, and clouding due to poor dispersion is prevented.

The monomer having such an epoxy group is used in an amount of 0.5 to 30% by weight of the total JLL polymer component including the monomer capable of forming the above-mentioned (meth)acrylic acid ester resin. If the amount used is less than 0.5% by weight, the fine particles of the (meth)acrylate resin produced will be difficult to immobilize on the epoxy resin;
If the weight exceeds 0 weight 2, there will be too many crosslinking points between epoxy groups inside the fine particles, and thermal stress will not be absorbed sufficiently.

In addition, the amount of the above two types of monomers used in the epoxy resin is 3 to 4 O per 100 parts by weight of the (meth)acrylic acid ester resin formed by polymerization.
The amount of N is preferably in the range of 5 to 25 parts by weight. That is, if the amount is less than 3 parts by weight, the effect of reducing thermal stress will be insufficient, and if it exceeds 40 parts by weight, the inherent heat resistance of the epoxy resin will decrease.

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, peroxides such as lauroyl peroxide that generate radicals when heated, ketones such as benzoin and dibenzyl ketone, and azobiscyanovaleric acid. Examples include compounds that generate radicals when irradiated with ultraviolet rays, such as azo compounds.

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 epoxy resins such as Talesol novolac type, phenol novolac type, and bisphenol A type are used for sealing semiconductor devices. Various epoxy resins used as stopper resins can be used, but those having a melting point above room temperature and exhibiting a solid or highly viscous state at room temperature are desirable.

As a novolac type epoxy resin, the epoxy equivalent is usually 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 curing agents for such epoxy resins, acid anhydrides,
Any of various known epoxy resin curing agents including phenol resin and polyamides can be used, but preferably novolac resins having a hydroxyl group of 1E70 to 150 (phenol novolak, Talesol novolank, 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, the resin composition of the present invention may contain fillers such as quartz glass powder, silica stone powder, Kuruk, etc., and other various additives, if necessary.

To #WA'A the resin composition used in this invention,
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.

The polymerization initiator used in producing the (meth)acrylic acid ester resin is preferably one that is soluble in both the monomer that is the starting material for producing the resin and the epoxy resin.

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)acrylic acid ester resin in a dispersed state.

Next, a curing agent, a 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. However, the sealing parts of these semiconductor devices have a good appearance with no clouding in the resin.

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

Examples 1 to 6 Each component with the composition shown in Table 1 below was put into a 500 ra 11 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 4th edition fat, each component was kneaded with a mixing roll machine at 100°C for 10 minutes with the composition shown in Table 3 below.
A sealing resin composition was obtained.

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 6 with the compositions shown in Table 2 below, and semiconductor devices were sealed in the same manner as in Examples 1 to 6.

Conventional Examples 1 and 2 Each component with the composition shown in Table 4 below was kneaded for 10 minutes using a mixing roll machine, and the resulting resin composition was used to seal a semiconductor device in the same manner as in Examples 1 to 6. went.

In addition, EVO is the epoxy resin shown in Table 1.2.4.
(A resin with a phenolic equivalent i of 190 and a softening point of 80°C was used as a phenol resin, a resin with a phenol equivalent of 130 and a softening point of 80°C was used, and a butadiene terminal carboxylic acid-acrylonitrile copolymer shown in Table 4 had a carboxyl equivalent of 1400. Resins with a copolymerization ratio of butadiene:acrylonitrile of 723 were 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 1000-hour reliability test using a pressure cooker (abbreviated as PCT), -50. ℃730min~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.

It should be noted that the (meth)acrylic acid ester monomer used in Examples 1 to 6 forms a resin with a glass transition temperature of room temperature or lower, and that the methacrylate monomer formed with the methyl methacrylate monomer in Comparative Example 4 It is well known that the glass transition temperature of acid methyl resin is higher than room temperature.

Margin below 1 Table 1 Number 1 1 1 21 31 41
．． 51 611 Epoxy resin 1 100
11001100110011001 10011 Butyl acrylate monomer 1 21101251- 1
- 1 -11 Acrylic acid engineered monomer 1 -1
-1- 1101 -1 -11 Lauryl methacrylate monomer 1 -1 -1- 1-1 101 101
1 Glycidyl methacrylate I O,0510,1
10,510,510,110,511 Benzoyl peroxide I O,0210,0510,1110
, 0510, 0510, 051 (unit: weight audience 2 Table 1 □ body 111213141 1 epoxy resin 1 1001100 1
100 110011 Butyl acrylate monomer +
51 -1 -1 -11 Acrynoethyl monomer! -1251-1-11 Lauryl methacrylate monomer 1 -1 -1 101 -11 Methyl methacrylate monomer 1 -1 -1- 1101 F: Benzoyl peroxide I O,0210,1
110,0510,051 (Unit: parts by weight p Table 1 Component 1 Parts by weight 1-1
Weird raw epoxy resin! 11011 Fukunono January 1 50 112-
Methylimidazole 10.511 Stearic acid
10.511 Fused silica powder 150
01 From the results in Table 5 above, the semiconductor devices obtained in each example according to the present invention have very low internal stress and are
The defective rate in the T test was almost 0, and no cracks occurred in the TCT test (it is clear that the product has excellent moisture resistance and thermal shock resistance and high reliability.

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) The main component is a reaction product obtained by polymerizing a monomer capable of forming a (meth)acrylic acid ester resin with a glass transition temperature below room temperature and a monomer having an epoxy group in an epoxy resin. A semiconductor device sealed with a resin composition.