JPS63128020A - Epoxy resin composition and resin-sealed type semiconductor device - Google Patents

Abstract

PURPOSE:To obtain an epoxy resin composition, having excellent molding operability as well as a low thermal expansion coefficient and useful for sealing semiconductors, by blending an epoxy resin with specific spherical fused quartz powder. CONSTITUTION:A composition obtained by blending (A) an epoxy resin with (B) spherical fused quartz powder containing >=90wt% particles having <=100mu particle size and particle size distribution exhibiting 0.6-1.5 gradient (n) when indicating the particle size distribution by an RRS particle size chart as a filler in an amount of >=80wt% based on the total composition.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an epoxy resin composition for encapsulating semiconductors that has excellent molding workability and a small coefficient of thermal expansion, and a resin-encapsulated semiconductor device using the composition. . .

[Conventional technology]

There are two types of exterior packaging for semiconductor devices such as transistors, IOs, and LSIs: a hermetic sealing type that uses metal, glass, ceramics, etc., and a resin sealing type that uses epoxy resin as the mainstream. The former has excellent airtightness but is very expensive. On the other hand, the latter can be manufactured extremely cheaply through mass production.

In recent years, the reliability of sealing resins has improved significantly, and now more than 80 of all semiconductor products are of the thermosetting resin type using thermosetting resins, mainly epoxy resins.

However, the degree of integration of semiconductor devices is increasing year by year, and as a result, chip sizes are becoming larger, wiring becomes finer, and the number of layers becomes larger. On the other hand, regarding the exterior (package), package sizes are becoming smaller and thinner due to higher density and automation of packaging, and the shape of the package is also changing from the conventional DILP (Dual in Lin
ePackage) to PPP (Flat P
lastic Packaqs), B OP (
SmallOutlinOPackage), P
L CO (Plastic Loaded 0bip C
arrier), etc., has shifted from the bottle insertion type to the surface mounting type. With the increase in the degree of integration, changes in package size or shape, mounting methods, etc., elements are becoming more delicate and the sealing resin 1- of the package is becoming increasingly thinner.

Therefore, when thermal stress is applied to the encapsulated product, thermal stress is generated due to the difference in thermal expansion coefficient of the encapsulating resin, frame, chip, etc. that make up the semiconductor device, which may cause cracks to occur in the encapsulating resin. On the other hand, cracks may occur in the chip or the passivation film formed on the chip surface, making it more likely that wiring on the chip surface will be cut, short circuits, etc. will occur, resulting in changes in device characteristics and reduced reliability. There is. This problem has been exacerbated by the shift in package mounting methods from pin-insertion type to surface-mount type, and the temperature conditions to which packages are exposed during mounting have become more severe than in the past.

Thermal stress that occurs in resin-sealed semiconductors is caused by the differences in the thermal expansion coefficients of each constituent material, as described above, so it is possible to reduce the thermal expansion coefficient of each constituent material, especially the sealing resin, which has a large coefficient of thermal expansion. if you can.

It becomes possible to significantly reduce thermal stress. Generally, in order to reduce the coefficient of thermal expansion, sealing resins are mixed with an inorganic optical filler whose coefficient of thermal expansion is smaller than that of the resin. It would be better to increase it even more than before. However, conventionally, if the filler blend t' is increased too much, the viscosity of the resin composition increases significantly and the fluidity decreases, making the sealing work difficult. That lick, Patent No. 8
Specifications of No. 02445, No. 855789 and Japanese Patent Publication No. 1986
As described in Publication No. 0-10533, a method has been proposed that uses an inorganic photonic agent having a specific particle size distribution to increase the amount of filler without significantly increasing the viscosity or decreasing the fluidity of the resin composition. has been done. However, even if such a method is used, the phenol-curing epoxy resin composition, which is currently the mainstream for resin-encapsulated semiconductors, has a high viscosity of the base resin itself, so it is difficult to dramatically increase the filling amount. The limit has been reached in achieving a significant reduction in the coefficient of thermal expansion.

The reason for this is that angular fillers made by mechanically crushing large rough stones have traditionally been used for such applications, and the bulk of the fillers increases the viscosity and reduces fluidity of the resin composition. It is presumed that it was easy. Therefore.

As a countermeasure, Special Publication No. 60-26505 and No. 60-
As disclosed in each publication No. 40188, a method using a spherical filler has been proposed, but a resin composition for sealing that can sufficiently cope with the above-mentioned high integration of elements and miniaturization and thinning of packages has been proposed. I haven't gotten anything yet.

On the other hand, thermal stress applied to a resin-sealed semiconductor element can also be reduced by lowering the elastic modulus or glass transition temperature of the sealing resin. However, lowering the glass transition temperature of the resin composition generally lowers high-temperature electrical properties, moisture resistance, etc., which is not preferable for semiconductor devices. Therefore, recently, a method of blending a rubber component such as silicone rubber or polybutadiene rubber into the paste resin to make the matrix epoxy resin have a seabird structure and reduce the elastic modulus of the cured product has been studied. However, although this method can reduce the thermal stress applied to the chip to some extent, it has little effect on reducing the difference in thermal expansion coefficient between the materials that make up the semiconductor device, and is not an essential measure to reduce thermal stress. .

[Problem that the invention seeks to solve]

Therefore, there has been a strong desire for an epoxy resin composition for semiconductor encapsulation that generates less thermal stress and a semiconductor device using the same.

The present invention has been made in view of the above-mentioned circumstances.The purpose of the present invention is to provide an epoxy resin composition that has good molding workability and a low coefficient of thermal expansion, and a mobile device using the resin composition. An object of the present invention is to provide a resin-sealed semiconductor device with excellent reliability.

[Means for solving problems]

To summarize the present invention, the first aspect of the present invention relates to an epoxy resin composition. 100μ for heavy weight and above
m or less, and its particle size distribution '1RR8
It has a particle size distribution that exhibits linearity with a slope n in the range of 16 to 1.5 when displayed on a particle size diagram, and the filler is blended in an amount of 80% by weight or more based on the entire composition. Features.

A second invention of the present invention relates to a resin-sealed semiconductor device, which is encapsulated with the epoxy resin composition of the first invention, and the sealing resin has a coefficient of thermal expansion of 1.3.
It is characterized by being less than or equal to X 10-'/C.

The above problems can be solved if a large amount of filler can be added without increasing the viscosity or impairing the fluidity of the resin. Therefore, the present inventors investigated in detail the relationship between the shape, particle size, particle size distribution, and filling slippage of the filler, the properties of the resin composition, and the reliability of semiconductor devices sealed with these resin compositions. .

As a result, 90 weight tons of it was used as a filler in epoxy resin.
% or more are within the particle size range of 100 μm or less, and the particle size distribution is shown in the particle size diagram as RR8.
It has been found that 800X'1 or more of spherical fused quartz powder exhibiting linearity in the range of α6 to 1.5 may be blended into the entire resin composition.

Here, the RRB particle size diagram is the Rosin-Ramular (
This is a particle size diagram showing particle size distribution according to the Rosin-Rammler formula.

R(Dp)""1006X'9 (-b-Dpl゛
(However, in the formula, R(Dp) is the cumulative t% from the maximum particle size to the particle size Dp, Dp is the particle size, and b and n are constants.) R(Dp)Vi integrated residual weight t in the formula Also called %.

In addition, the slope in the RR8 grain size diagram is represented by a straight line connecting two points where the cumulative weight range from the maximum grain size to the grain size Dp in the RR8 grain size diagram is at least within the range of 25 weight plate 75 weight plate. It refers to the n value of the Rosin-Ramler equation. Generally, when the filler raw stone is finely pulverized, its particle size distribution conforms to the Rosin-Rammler equation, and it is said that the RR8 particle size diagram, which is a way to express the particle size distribution based on this equation, shows almost linearity. The present inventors measured the particle size distribution of various fillers and found that unless special sieving is performed, all fillers are 90 times heavier! It has been confirmed that 4 or more shows almost linearity in the above RRB grain size diagram and fits well with the above formula. Spherical fused quartz powder having such a particle size distribution can be obtained by mixing angular fused silica powder, which has been crushed in advance to a predetermined particle size distribution, with propane, butane, and hydrogen, as shown in, for example, Japanese Patent Application Laid-Open No. 59-59737. It is obtained by supplying a fixed amount of fuel into a high-temperature flame generated from a thermal spraying device using fuel such as fuel, melting it, and cooling it.

When used as a filler in an epoxy resin, its particle size is within the range of 100 μm or less with a particle diameter of 90 μm or more, and its slope n is 1.
By blending spherical fused quartz powder with linearity in the range of 16 to 1.5 at least 80% by weight based on the entire resin composition, the resin composition has a relatively high viscosity despite the large amount of filler blended. is low and has excellent fluidity, and the cured product has a thermal expansion coefficient of 1.
．． It is small, less than 3 X IQ-8/℃. Therefore, even if a semiconductor element bonded with Au wire is sealed, deformation or disconnection of the Au wire may occur.Also, since the sealed product generates less thermal stress, it has good temperature cycle resistance, heat resistance, Good moisture resistance etc.

The epoxy resin composition in the present invention is an epoxy resin composition that is currently commonly used as a molding material for semiconductor encapsulation, and includes a Vsol novolac type epoxy resin,
Phenol novolac type epoxy resin, bisphenol A type epoxy resin, etc. are blended with phenol novolac resin as a curing agent, curing accelerator, filler, softening agent, coupling agent, colorant, flame retardant, mold release agent, etc. The composition is The reason why spherical fused silica powder is used as a filler is that, as mentioned above, by making it spherical, the bulk of the filler is reduced, making it easier to achieve a high filling rate. It also has the effect of preventing the elements from touching the surface of the element and damaging the element or adversely affecting the characteristics of the element. Fused quartz is easy to obtain, has a relatively small coefficient of thermal expansion and is therefore effective in reducing the thermal expansion of resin compositions, and has an extremely low content of ionic impurities. The reason why the filler is limited to a particle size of 90 weight Jt% or more/> 1θ0 μm or less is that if there are too many coarse particles of more than 100 μm, the Au wire may be deformed or cut during sealing, or This is because coarse particles cause clogging in the mold when sealing the package, resulting in resin filling failure.The slope n shown in the RR8 particle size diagram is
The reason why n is set to 1.5 is because if n exceeds 1.5, that is, if the particle size distribution is extremely narrow, the bulk of the filler increases significantly, causing an increase in the viscosity and a decrease in fluidity of the resin composition. Ru. On the other hand, reducing the gradient height f means increasing the amount of fine particles in the filler, but if the amount of fine particles increases too much, the resin composition exhibits chicken-tropic properties, resulting in a significant increase in viscosity and poor fluidity. happens.

In order to prevent this, n is preferably α6 or more.

Although the epoxy resin composition of the present invention contains a large amount of filler, it can be produced in exactly the same manner as conventional molding materials for semiconductor encapsulation, and furthermore, the epoxy resin composition of the present invention can be produced in exactly the same way as the conventional molding material for semiconductor encapsulation. You can do it.

That is, each material is kneaded with a twin-screw roll or extruder heated to 70 to 100 tons, and then kneaded with a transfer press at a mold temperature of 160 to 190°C and a molding pressure of 30 to 100 kll/
'5'', can be molded in 1 to 3 minutes curing time.

〔Example〕

Hereinafter, the present invention will be explained in more detail with reference to Examples.
The invention is not limited to these examples.

Examples 1-5. and Comparative Examples 1 to 4 Using each lightning agent shown in FIG. 1, an epoxy resin composition having the formulation shown in Table 1 was kneaded for about 10 minutes with a twin-screw roll heated to about 80°C. Obtained 1. 18 About each composition
Gelation time at 0°C (G.

? , ) by JXB-K 5909 hot plate method, 1
The minimum melt viscosity (ηmin) at 80C was measured using a high-performance flow tester, and spiral 0-(&,?,) ftNMMX was measured as a measure of the fluidity of the composition.
- According to 1-66, mold temperature 180C1 molding pressure cuff 0
kli/ex”.

The measurement was performed with a molding time of 1.5 minutes. The results are summarized in Table 1.

In addition, FIG. 1 shows the relationship between the grain size Dp (μm, horizontal axis) of fused silica of various shapes and gradients n and the cumulative weight % from the maximum grain size to the grain size Dp (R (DI)). It is a graph.

As is clear from Table 1, the composition of the present invention has RRS
The slope n of the grain size diagram is less than 16 or 1.5
Compared to the composition using larger spherical fused quartz and the composition using prismatic fused quartz, the gelation time is almost the same and there is no difference in hardenability, but the melt viscosity is extremely low and the fluidity is poor. I know it's big.

Example 4.5% and Comparative Examples 5 to 7 Spherical fused silica (sphere-2) shown in FIG. 1 as a filler
and square fused quartz (square-2), the filler compounding amount was 70.75.80 and 85Ii in the same manner as in the above example.
A quantitative resin composition was prepared. Using this composition, φ1
0XIDO- round bar was transfer molded and heated to 180'C.
A8TM-0696-4 after secondary curing for /A hours
The thermal expansion coefficient was measured according to 4K, and the glass transition temperature was determined from the inflection point.

Also, gold 1 as shown in Figure 2! Thermal stress applied to the metal cylinder when the inner cylinder made of (SUB) was molded was measured using a L/in gauge attached to the inside of the metal cylinder.

That is, FIG. 2 is a schematic cross-sectional view of an apparatus for measuring thermal stress of a resin composition according to the present invention. In Fig. 2, numeral 1 is resin, 2 is a strain gauge, 3Fi thermocouple, and 4 is @(e
u s ) means a manufactured inner cylinder, and the unit of each numerical value of diameter and height is -.

Furthermore, a semiconductor element having aluminum zigzag wiring was sealed on the surface of a silicon wafer, and this sealed product was subjected to a thermal cycle test (-55°C/30 minutes #150°C/30 minutes).
) to check the crack resistance of the sealing layer and +? - Connection reliability between wire, gold wire and aluminum wire (resistance value is 50%)
(If the change was more than 100%, it was determined to be defective). The results of Kotoriki et al. are summarized in Table 2.

From Table 2, it is clear that the compositions of the Examples containing 80% by weight or more of filler have extremely small coefficients of thermal expansion of the cured products, and the thermal stress applied to the inserts is significantly reduced.

Further, it can be seen that the semiconductor device sealed with such a resin composition has extremely excellent crack resistance of the sealing resin layer and wiring connection reliability when subjected to thermal shock in a thermal cycle test.

〔Effect of the invention〕

As explained above in detail, the resin composition of the present invention has a small curing shrinkage rate, and therefore has the effect of improving the dimensional accuracy of the molded product.

Moreover, the resin composition of the present invention t? When used for resin encapsulation of semiconductors, it is possible to prevent wiring misalignment due to its excellent molding workability, the excellent crack resistance of the cured resin, and its low curing shrinkage rate. By preventing damage to the surface interlayer insulating film of the element, a remarkable effect is achieved in that the reliability of the obtained semiconductor device is improved.

[Brief explanation of the drawing]

FIG. 1 is a graph showing the relationship between the grain size of fused silica of various shapes and gradients n and the cumulative stacking plate from the maximum grain size to the grain size DX)t. This is a schematic cross-sectional view of the apparatus for measuring thermal stress of compositions. 1: Resin, 2 Ni strain gauge, 3: Thermocouple. 4: Steel (8U8) inner cylinder

Claims (1)

[Scope of Claims] 1. In an epoxy resin composition in which spherical fused silica powder is blended as a filler into an epoxy resin, 90% by weight or more of the filler has a particle size of 100 μm or less, and It has a particle size distribution that exhibits linearity with a slope n in the range of 0.6 to 1.5 when the distribution is expressed in an RRS particle size diagram, and the filler is blended in an amount of 80% by weight or more based on the entire composition. An epoxy resin composition characterized by: 2. 90% by weight or more of the filler made of spherical fused silica powder has a particle size of 100 μm or less, and when the particle size distribution is expressed in an RRS particle size diagram, the slope n is 0.6 to
It is sealed with an epoxy resin composition containing 80% by weight or more of the filler having linearity in the range of 1.5, based on the total composition, and the sealing resin has a coefficient of thermal expansion of 1.3 x 10^- ^
A resin-sealed semiconductor device characterized in that the temperature is 5/℃ or less.