JPS62151447A - Epoxy resin composition for sealing semiconductor - Google Patents

Abstract

PURPOSE:An epoxy resin composition having improved water-vapor resistance and improved molding workability, containing synthetic, low alpha-ray spherical silica and low alpha-ray square silica having specific maximum particle diameters and comprising coarse particles of the silica in a specific ratio. CONSTITUTION:(A) Synthetic low alpha-ray spherical silica having 149mum maximum particle diameter, preferably obtained by melting AKOROZURU R as a raw material and processing it into spheres and (B) low alpha-ray square silica having 74mum maximum particle diameter obtained by mechanically grinding synthetic silica or natural silica are both used in such a way that coarse particles having >=44mum are >=6wt% based on the total amounts of the component A+B and content of the component B is 10-70wt% and th silicas are blended with an epoxy resin (preferably O-cresol novolak type epoxy resin having 180-205 epoxy equivalent), a curing agent (novolak type phenolic resin, etc.), a curing promotor (2-methylimidazole, etc.), etc., in a molten state.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an epoxy resin composition for encapsulating semiconductors (hereinafter abbreviated as encapsulating material) having excellent reliability and moldability.

[Conventional technology]

Resin encapsulation of semiconductor devices (TR3, IC, LSI, etc.) by transfer molding using a encapsulating material is the mainstream encapsulation method due to its high productivity. Furthermore, as the reliability of encapsulants has improved, their range of application has expanded to include VLSI devices such as memories and microcomputers. Particularly in recent years, the degree of integration has been significantly improved, and correspondingly, taking dynamic memory as an example, the aluminum wiring width has increased to about 5 μm for 16 bits, about 3 μm for 64 bits, and about 2 μm for 256 bits. There is a trend towards miniaturization. Furthermore, the element size has also increased to about 20 mm for 16 bits and about 30 mm for 64 bits, and about 40 mm for 64 bits. As a result, sealing materials are required to have even higher reliability. Conventionally, improvements in moisture resistance have been achieved by increasing the purity of the material. In addition, in order to reduce the thermal stress caused by the difference in expansion coefficient between the encapsulant and the element as the element size increases, formulations that reduce the expansion coefficient or elastic modulus of the encapsulant are required. has been used. However, with the rapid increase in the degree of integration of devices,
These measures alone have reached their limits.

[Problem that the invention seeks to solve]

An object of the present invention is to provide an industrially useful sealing material that has excellent moisture resistance and good molding workability when sealing highly integrated and finely interconnected elements.

[Means for solving problems]

The epoxy resin composition for semiconductor encapsulation of the present invention is characterized by containing (synthetic paper α-ray spherical silica with an al maximum particle size of 149 μm and fb) low α-ray prismatic silica with a maximum particle size of 74 μm.

256 as a representative example of a resin-sealed semiconductor device.
As a result of examining the failure mode in a 120°C pre-shark test for bit memory, we found the following. Corrosion occurs most often in the aluminum band parts around the fil element, but it takes a long time to develop defects. (2) Corrosion defects also occur near the center of the element. Although the number of defects is small, the problem is that the time required for defects to occur is short, and defects occur in a short period of time.

Conventional techniques for improving the purity of materials and reducing stress have been effective in improving corrosion defects that occur in the periphery of the element, but have little effect on improving corrosion defects that occur in the center of the element. Ta. As a result of investigating the cause, it was found that the failure in the central part of the element was due to a defect in the passivation film. Therefore, we further investigated the relationship between defects in the passivation film and the encapsulant, and found that by reducing the amount of coarse filler, defects in the passivation film become less likely to occur, and as a result, corrosion defects are significantly reduced. Ta.

Generally, the maximum particle size of the sealant is 149μm, and the average particle size is 10~
50-70vol with 20μm square silica as filler
Contains %. In the present invention, since defects in the passivation film are thought to be caused by scratches on coarse prismatic particles, synthetic paper α-ray spherical silica with a maximum particle size of 149 μm is used together with prismatic silica with a maximum particle size exceeding 74 μm. By removing this, the passivation film was not damaged and corrosion defects at the center of the element were prevented.

In addition, synthetic α-ray spherical silica has a low content of U, which is an α-ray generating source, and is therefore suitable for use in highly integrated memories. The maximum particle size of synthetic paper α-ray spherical silica is 149
If it exceeds μm, it will not flow through the narrow channel in the mold, which is undesirable.

As mentioned above, when the low α-ray prismatic silica having a roughness of 74 μm or more is excluded, the sealing material flows out from the gap of 40 μm or more in the mold, causing flaking, and the workability is not sufficient. Therefore, it is preferable that the coarse particles of 44 μm or more in the total amount of fa) + fbl be 5 wt % or more, and the content of (bl be 10 to 70 wt %), since this will prevent the generation of flakes and improve workability.

That is, if the amount of black particles is less than 5 wt%, paris will occur, which is not preferable. Furthermore, when spherical silica is used alone, the sealing material tends to flow out (splash generation) over the entire area from the thin gap of the mold to the thick gap of 40 μm or more, which significantly impairs workability. This problem can be solved by using prismatic silica. If the content is less than 1Qwt%, there is no effect (70w
If it exceeds t%, thin paris will no longer occur, but 4
Thick paris of 0 μm or more are likely to occur.

As the synthetic paper α-ray spherical silica, for example, one obtained by melting and spheroidizing Aerosil ■ (manufactured by Mitsubishi Metals) is suitable. Further, as the low α-ray prismatic silica, mechanically pulverized synthetic silica or natural silica can be used.

Epoxy resins that can be used in the present invention include, for example, glycidyl ethers of phenols such as bisphenol A, bisphenol F lu-sorcinol, and phenol novolak, glycidyl ethers of alcohols such as butanediol, polyethylene glycol, and polypropylene glycol, and phthalic acid. , glycidyl esters of carboxylic acids such as isophthalic acid, terephthalic acid, and tetrahydrophthalic acid, glycidyl-type epoxy resins such as those in which the active hydrogen bonded to the nitrogen atom is replaced with a glycidyl group such as aniline and isocyanuric acid, and olefins in the molecule. Examples include so-called alicyclic epoxides obtained by epoxidizing a bond with a peracid or the like. Among them, 0-cresol novolac type epoxy resins having an epoxy equivalent of 180 to 205 are the most suitable because they have excellent heat resistance such as strength<iH interface and glass transition temperature.

There are no particular restrictions on the curing agent, but phenolic resins such as novolak-type phenolic resins and novolac-type cresol resins, acid anhydrides such as tetrahydrophthalic anhydride and pyromeronotic anhydride, amines such as diaminodiphenylsulfone, and adipic acid Dibasic acid dihydrazides such as dihydrazide and isophthalic acid dihydrazide can be used. These are preferably used in an equivalent ratio of 0.5 to 1.5 with respect to the epoxy group, and two or more types may be used in combination.

Examples of the curing accelerator include imidazoles such as 2-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, and 2-heptadecyl imidazole, benzyldimethylamine, and ■,8-diazabicyclo[5゜4 .0] Undecene-7 (abbreviated as DBU), phenol salts of DBU, novolak resin salts of DBU, DBU derivatives such as Kalibol salt of DBU, tributylphosphine, methyldiphenylphosphine, diphenylphosphine, triphenylphosphine , organic phosphines such as phenylphosphine,
Examples include tetraphenylboron salts such as tetraphenol phosphonium tetraphenylborate and 2-ethyl-4methylimidazole tetraphenylborate.

In addition, if necessary, rubbers such as polybutadiene and acrylonitrile-butadiene copolymer, modified rubbers having terminal carboxy, hydroxy, internal epoxy, etc., silicone oil, silicone rubber, silicone gel, various types can be used as flexibilizers. Organopolysiloxanes such as silicone compounds having functional groups or organic groups, fluorine compounds such as Teflon, fluorine rubber, etc. can be used. In addition, phthalic acid diesters, aliphatic dibasic acid esters, glycol esters, and the like can be used as known plasticizers.

In addition, a coloring agent, a mold release agent, a flame retardant, a coloring agent, a camping agent, etc. can be used as necessary.

As a method for producing the epoxy resin composition of the present invention, a melt mixing method using a mixing roll or an extruder is suitable, and a composition with desired fluidity can be produced by these methods.

〔Example〕

The present invention will be explained below with reference to Examples, but the scope of the present invention is not limited to these Examples.

Table 1 shows the particle size of the silica used.

Below is a margin Table 1 Silica particle size book Measured values using a JIS Z 8801 standard sieve Example 1 80 parts by weight of 0-cresol novolac type epoxy resin (41i195 per epoxy), Br bisphenol A epoxy resin (epoxy equivalent 400, Br conversion rate: 48%)2
0 parts by weight, 50 parts by weight of novolac type phenolic resin,
1 part by weight of 2-methylimidazole, antimony trioxide
10 parts by weight, 3 parts by weight of T-glycidoxypropyltrimethoxysilane, 2 parts by weight of Karunahawa 7x, 2 parts by weight of carbon black, and spherical A as a filler.
Using 320 parts by weight of B and 80 parts by weight of square B, the blended composition was melted in a mixing roll at 80°C for 5 minutes according to a conventional method, taken out in a sheet form, cooled and crushed to form a sealing material. Created.

Example 2 200 parts by weight of spherical A and 20 parts by weight of square B as fillers
A sealing material was produced in the same manner as in Example 1 except that 0 parts by weight was used.

Example 3 120 parts by weight of spherical A and 28 parts by weight of square B as fillers
A sealing material was produced in the same manner as in Example 1 except that 0 parts by weight was used.

Comparative Example 1 A sealing material was produced in the same manner as in Example 1, except that 400 parts by weight of spherical A was used alone as a filler.

Comparative Example 2 A sealing material was produced in the same manner as in Example 1, except that 400 parts by weight of square B was used alone as a filler.

Table 2 shows the results of Examples and Comparative Examples.

Margin Table 2 below *Evaluation was performed using a 16-pin DIP using a device with a wiring width of 1.5 μm and a size of 42 mm2. Humidification is 120℃, 10
Testing was carried out for 1000 hours at 0% RHM, and the number of moisture resistance failures due to corrosion was counted.

** Using a mold with slits of a predetermined thickness such as 50 μm or 10 μm, the mold temperature is 180°C and the molding pressure is 70 kg /
The outflow length was determined under the conditions of ``swa''. The level shown in Comparative Example 2 is the standard.

〔Effect of the invention〕

According to the present invention, an industrially useful sealing material with excellent moisture resistance was obtained.

Agent: Patent attorney Kunihiko Wakabayashi, PA) Masano+-, 7'

Claims (1)

[Claims] 1. An epoxy resin for semiconductor encapsulation characterized by containing (a) synthetic low α-ray spherical silica with a maximum particle size of 149 μm and (b) low α-ray prismatic silica with a maximum particle size of 74 μm Composition. 2. Out of the total amount of (a) + (b), 6 wt% or more of coarse particles of 44 μm or more are contained, and the content of (b) is 10 to 70 wt%, Claim 1 The epoxy resin composition for semiconductor encapsulation described above.