JPH0583113B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to an epoxy resin composition for semiconductor encapsulation that provides a cured product with excellent moisture resistance, and a semiconductor device encapsulated with the cured product of the composition. BACKGROUND ART Conventionally, epoxy resin compositions containing an epoxy resin, a curing agent, and an inorganic filler have often been used as sealing materials for semiconductor devices. However, when epoxy resin compositions are used to encapsulate semiconductor devices, there are problems with moisture resistance.
Although it has been proposed to add a trapping agent for ionic impurities to the composition, it is virtually impossible to completely and reliably remove or trap ionic impurities, and therefore it is difficult to improve moisture resistance by such a method. has certain limits. Additionally, as another means of improving the moisture resistance of epoxy resin compositions for semiconductor encapsulation, it has been proposed to add silane coupling agents, particularly 3-glycidoxypropyltrimethoxysilane, 2-(3,
Epoxy-based alkoxysilanes such as 4-epoxycyclohexyl)ethyltrimethoxysilane, 3-
Mercapto alkoxysilane such as mercaptopropyltrimethoxysilane, γ-aminopropyltrimethoxysilane, N-(2-aminoethyl)-
It is known to add amine alkoxysilanes such as 3-aminopropylmethyldimethoxysilane, unsaturated hydrocarbon alkoxysilanes such as vinyltriethoxysilane, and 3-methacryloxypropyltrimethoxysilane. However, the use of the above-mentioned epoxy-based alkoxysilanes has the problem of generating burrs during molding and decreasing electrical properties as the amount added increases. Furthermore, epoxy resin compositions containing these epoxy-based alkoxysilanes The adhesion to silicon chips is insufficient, and semiconductor devices encapsulated using this have the disadvantage that they are likely to fail in moisture resistance tests under especially severe conditions. Further, the use of mercapto-based alkoxysilanes has the problem of bad odor, and the use of amine-based alkoxysilanes has the problem of worsening the storage stability of the composition. Furthermore, since unsaturated hydrocarbon alkoxysilanes do not have a functional group that reacts with phenol-curable epoxy resins, they have the disadvantage that they do not function adequately as coupling agents. In particular, silica, alumina, etc. can be used as an inorganic filler in an epoxy resin composition for semiconductor encapsulation, but when alumina is used as a filler, an alkoxysilane having the above-mentioned functional group may be added. However, compared to the case where silica is used as a filler, it cannot provide sufficient moisture resistance, and there is a problem that the moisture resistance is inferior. The present invention was made in view of the above circumstances, and provides an epoxy resin composition for semiconductor encapsulation that can solve the problems when using the above-mentioned functional alkoxysilane and provides a cured product having excellent moisture resistance, and the composition. An object of the present invention is to provide a semiconductor device sealed with a cured product. Means and Effects for Solving the Problems The present inventors have carried out extensive studies in order to obtain an epoxy resin composition for semiconductor encapsulation that provides a cured product with excellent moisture resistance, and have found that the following general formula (1)

[Formula, R ¹ is an organic group having an epoxy group, R ² ,
R ³ and R ⁴ each represent a hydrogen atom, an alkenyl group, an aryl group, or an aralkyl group, and these may be the same or different. n,m
are respectively 0, 1, 2, or 3, 1≦n+m≦3
It is. ), the cured product exhibits extremely excellent moisture resistance, and even if a semiconductor device sealed using this composition is left at high temperature and high humidity for a long time, aluminum will remain intact. It has been found that corrosion of the wiring can be effectively prevented and the above object can be effectively achieved. Furthermore, it was discovered that the use of the propenoxy group-containing organosilicon compound provides excellent moisture resistance even when alumina is used as an inorganic filler, leading to the present invention. It is known that a propenoxy group-containing organosilicon compound is used in combination with an epoxy resin and a curing agent (Japanese Patent Publication No. 52-52892). However, this is a general-purpose epoxy resin that aims to improve its curing characteristics, storage stability, and adhesive properties.
It relates to a liquid type room temperature curable composition, and the above
Blending the propenoxy group-containing organosilicon compound of formula (1) into an epoxy resin composition for semiconductor encapsulation;
It is a new finding of the present inventors that this provides a semiconductor encapsulated product with excellent moisture resistance, and in particular, provides outstanding moisture resistance to a composition containing alumina as a filler. Therefore, the present invention provides an epoxy resin composition for semiconductor encapsulation containing (a) an epoxy resin, (b) a curing agent, (c) an inorganic filler, and (d) an organosilicon compound of formula (1). and a semiconductor device sealed with a cured product of the composition. The present invention will be explained in more detail below. The epoxy resin used in the epoxy resin composition for semiconductor encapsulation of the present invention is not particularly limited as long as it has one or more epoxy groups in one molecule.
For example, bisphenol type epoxy resins, alicyclic epoxy resins, cresol novolak type epoxy resins, etc. are preferably used, and it is particularly desirable to use cresol novolak type epoxy resins. In addition, from the viewpoint of moisture resistance of the composition, the above epoxy resin should have a hydrolyzable chlorine content of 500 ppm or less,
It is preferable to use one having free Na and Cl ions of 2 ppm or less each and an organic acid content of 10 ppm or less. In addition, the curing agent used is appropriate for the epoxy resin, such as anhydrides such as trimellitic anhydride and tetrahydrophthalic anhydride, and phenol novolak resin, among which it is most suitable to use phenol novolak resin. be. In addition,
The phenol novolak resin used as a curing agent contains 2 ppm or less of free Na and Cl ions each, 1% or less of phenol as a monomer, and contains formic acid, etc., which is generated by the cannizaro reaction of trace amounts of formaldehyde remaining during manufacturing. The organic acid of
It is preferably 100ppm or less, free Na,
If the content of Cl ions or organic acids is higher than the above values, the moisture resistance of semiconductor devices sealed with the composition may deteriorate, and if the amount of phenol in the monomer is higher than 1%, molded products made with the composition may deteriorate. Defects such as voids, unfilling, and sink marks may occur in the Furthermore,
The softening point of phenol novolac resin is 50-120℃
If the temperature is less than 50°C, the glass transition point of the composition may become low and the heat resistance may deteriorate; if it exceeds 120°C, the melt viscosity of the composition may become high and the workability may be poor. arise. Here, the blending amount of the curing agent is not particularly limited, but the molar ratio of the epoxy group of the epoxy resin to the phenolic hydroxyl group or acid anhydride group of the curing agent is in the range of 0.8 to 2, particularly 1 to 1.5. It is preferable that If the molar ratio of both groups is less than 0.8, the curing characteristics of the composition and the glass transition temperature (Tg) of the molded product will decrease.
If it is greater than 2, the glass transition temperature and electrical properties of the molded product may deteriorate. Furthermore, it is preferable to add a curing accelerator to the composition of the present invention in order to promote the reaction between the epoxy resin and the curing agent. As the curing accelerator, compounds normally used for curing epoxy compounds, such as imidazole compounds, undecene compounds such as 1,8-diazabicyclo(5.4.0) undecene-7 (DBU), and phosphine compounds such as triphenylphosphine, etc. are used. However, from the viewpoint of moisture resistance of the composition, it is preferable to use triphenylphosphine. Note that the amount of the curing accelerator used is not particularly limited, and may be a normal amount. Further, the inorganic filler is not particularly limited and any known filler may be used, but quartz powder and alumina are most suitable. The use of quartz powder is suitable in terms of the moldability of the composition and the ability to lower the linear expansion coefficient of the cured product, but the quartz powder may be either amorphous or crystalline. In this case, the use of crystalline quartz powder is particularly effective for improving thermal conductivity, and the use of amorphous quartz powder is effective for lowering the coefficient of linear expansion. In addition, in order to increase the fluidity of the composition,
The use of spherical amorphous quartz is more effective.
The purity of these quartz powders is 98.0% or higher, especially
It is preferable to set it to 99.0% or more. The average particle diameter of the above quartz powder is 5 to 50 μm, especially
The thickness is preferably 10 to 40 μm. If the average particle size is too small, the viscosity of the composition may increase too much and gold wire flow may occur, while if the average particle size is too large, it may cause problems, especially when molding small objects using a mold with a small gate. Occasionally, the mold gate opening may become clogged with quartz powder. Note that it is preferable that the amount of coarse particles in the quartz powder be as small as possible, and it is particularly preferable that the amount of particles of 200 μm or more is 0.2% or less. If the amount of coarse particles is too large, the rate of unfilling during transfer molding may increase. The amount of quartz powder to be used is not limited and can be selected as appropriate, but from the viewpoint of linear expansion coefficient, crack resistance, or composition viscosity, it should be 100 to 600 parts by weight based on the total amount of the epoxy resin and curing agent 100 parts by weight. parts by weight, especially 150
The amount is preferably 300 parts by weight. On the other hand, the use of alumina is suitable in terms of increasing the thermal conductivity of the epoxy resin composition. In this case, in terms of moisture resistance, the purity of alumina is 99.5%.
The content of Na ₂ O is 0.03% or less, and
Na ion content when extracted with water at 100℃
It is recommended to use α-alumina having a Cl ion content of 5 ppm or less, a Cl ion content of 1 ppm or less, an average particle size of 5 μm to 60 μm, and a content of particles with a particle size of 250 μm or more of 1% or less. That is, when such α-alumina is used, a thermal conductivity that is approximately twice or more than that of a composition using crystalline silica in the same amount can be obtained, and the composition also has good fluidity and moisture resistance. , an epoxy resin composition having high thermal conductivity, moldability, and moisture resistance can be obtained. To explain this α-alumina in more detail, it is α-crystalline particles of alumina, and the aluminum oxide (Al ₂ O ₃ ) content, that is, the purity is 99.5% or more, preferably 99.8% or more. used for. If you use something with a purity of less than 99.5%,
The moisture resistance properties of the composition may be poor. Such α-alumina is generally produced by using bauxite containing alumina hydrate as a raw material, crushing it, putting it in a sodium hydroxide solution, and melting it with steam heating at 150 to 250°C to form sodium aluminate. After production, the resulting aluminum hydroxide is hydrolyzed and then fired at a temperature of 1000°C or higher.
In this case, Na ₂ O tends to remain as an impurity in α-alumina. Therefore, as α-alumina,
By removing this Na ₂ O, the total Na ₂ O content is reduced to 0.03g.
Hereinafter, the content of Na ions should be preferably 0.01% or less, and the content of Na ions should be 5ppm or less, preferably 2ppm or less, when 20g of this α-alumina was added to 100g of ion-exchanged water and extracted at 100℃ for 2 hours. It is desirable to use a material with a content of 1 ppm or less, preferably 0.5 ppm or less. If the Na ₂ O content and the Na ion and Cl ion contents of α-alumina are higher than the above values, the moisture resistance of the composition may deteriorate. Note that the method for producing α-alumina is as follows:
In addition to the above method, for example, (a) high-purity Al pellets are placed in a reaction tank filled with pure water, an electrode is inserted into the tank and a high-frequency spark discharge is generated, and the Al pellets are reacted with water to produce aluminum hydroxide. (b) Hydrolyzing distilled and purified alkyl aluminum or aluminum alcoholate to form aluminum hydroxide, and calcining this to obtain α-alumina. can be mentioned. Furthermore, the α-alumina used has an average particle size of 5 to 60 μm, preferably 10 to 50 μm, and the proportion of particles having a particle size of 250 μm or more is 1% or less, preferably 0.5% or less of the total. It is preferable that The average particle size of α-alumina is
If the particle size is smaller than 5 μm, the fluidity of the composition may deteriorate, and if the average particle size is larger than 60 μm or if the particle size is 250 μm or more and is present in an amount greater than 1%, gold may be lost when molding the composition. There is a risk that the mold will become severely worn, or the gate portion of the mold will become clogged with alumina particles, resulting in unfilling and deterioration of moldability. Furthermore, since α-alumina is usually produced by firing aluminum hydroxide, α-crystal particles tend to gather during the process to form secondary particles. These secondary particles cannot be loosened during the manufacturing process of the epoxy resin composition, and are made into a composition as is, and when a semiconductor device is made from a composition containing these secondary particles, the inside of the molded body becomes porous; In some cases, water may enter the semiconductor device and the moisture resistance characteristics of the semiconductor device may become extremely poor. Therefore, the content of secondary particles in α-alumina is preferably 10% or less, more preferably 1% or less of the total α-alumina. In addition, α-alumina preferably has an axial ratio between the major axis and the minor axis of α particles of 1 to 2, particularly 1.2 to 1.7, when α particles are observed in a scanning electron micrograph. If α-alumina is used, the fluidity of the composition may deteriorate. The blending amount of α-alumina is not particularly limited and may be selected as appropriate. In this case, a composition with higher thermal conductivity can be obtained by increasing the blending amount of α-alumina, but preferably 60 to 95% (wt%, the same applies hereinafter) of the entire composition, especially 75 to 90%. It is. If the amount of α-alumina blended is less than 60%, the thermal conductivity of the composition may be low, and if it is more than 95%, the composition may have poor fluidity. In addition, in the present invention, one type of the above-mentioned fillers may be used alone or two or more types may be used in combination as the filler. In addition to the above-mentioned components, the composition of the present invention contains the following general formula (1):

[Formula, R ¹ is an organic group having an epoxy group, R ² ,
R ³ and R ⁴ each represent a hydrogen atom, an alkenyl group, an aryl group, or an aralkyl group, and these may be the same or different. n, m
are respectively 0, 1, 2, or 3, 1≦n+m≦3
It is. ) is added. In this case, R ¹ is specifically

【formula】

【formula】

Examples include [Formula]. Here, R ⁵ is −CH ₂ CH ₂ −

【formula】

[Formula] Represents a divalent hydrocarbon group having 2 to 5 carbon atoms such as -CH ₂ CH ₂ CH ₂ -. In addition, lower alkyl groups of R ² , R ³ , and R ⁴ include methyl, ethyl, propyl, etc., alkenyl groups include vinyl, allyl, etc., and aryl groups include phenyl, tolyl, etc. , benzyl group, etc. are exemplified as the aralkyl group. Specific examples of such organosilicon compounds include the following.

[ka]

[ka]

[ka]

[ka]

[Formula] The above organosilicon compound contains an epoxy group, but as in the case of using the above-mentioned epoxy-based alkoxysilane, it may cause burrs during molding, decrease in electrical properties, and adhesion to silicon chips. Problems such as a decrease in the amount of water are unlikely to occur. The organosilicon compounds of formula (1) above may be used alone or in combination of two or more, but these organosilicon compounds include Na, Cl, and It is preferable to use 300 ppm or less, especially 5 ppm or less of each. The amount of this organosilicon compound is the inorganic filler.
0.05 to 10 parts by weight, especially 0.2 to 1 part by weight per 100 parts by weight
Preferably, it is expressed in parts by weight. If the amount is less than 0.05 parts by weight, the moisture resistance may not be sufficiently improved by addition, and if it exceeds 10 parts by weight, burrs will increase during molding, and the moisture resistance of the cured product may deteriorate. There is no particular restriction on the method of adding the organosilicon compound of formula (1), and a normal mixing method can be adopted, but a method in which it is well mixed with an inorganic filler is particularly preferred. For example, an integral blend or an organosilicon compound is added. Preferred methods include diluting with a solvent such as acetone, methanol, water, etc., mixing this with the inorganic filler, drying to scatter the solvent, and attaching the organosilicon compound to the surface of the inorganic filler. Can be adopted. Various additives may be added to the composition of the present invention if necessary, such as waxes such as carnauba wax, mold release agents such as fatty acids such as stearic acid, and metal salts thereof (among others, adhesive properties, Carnauba wax is preferably used in terms of mold releasability),
One or two types of organic rubber-based or silicone-based flexibility imparting agents, pigments such as carbon black, cobalt blue, red iron, flame retardants such as antimony oxide and halogen compounds, anti-aging agents, and other additives. The above can be blended. Further, in this case, a known alkoxysilane may be added to the extent that the effects of the present invention are not impaired. The epoxy resin composition of the present invention is manufactured by uniformly stirring a predetermined amount of the above-mentioned components,
A kneader that has been mixed and preheated to 70-95℃,
Knead with rolls, extruders, etc., cool,
It can be obtained by methods such as crushing. Here, there is no particular restriction on the order of blending the components. As mentioned above, the epoxy resin composition of the present invention is used for sealing semiconductor devices such as ICs, LSIs, transistors, thyristors, and diodes, and can also be effectively used for manufacturing printed circuit boards. Here, when sealing the semiconductor device, conventionally used molding methods such as transfer molding, in-die molding, and casting can be used. In this case, the molding temperature of the epoxy resin composition is 150 to 180℃, and the post cure is
It is preferable to carry out the reaction at 150 to 180°C for 2 to 16 hours. Effects of the Invention As explained above, the epoxy resin composition for encapsulating semiconductor devices of the present invention provides a cured product with excellent moisture resistance by blending the organosilicon compound of formula (1). A semiconductor device sealed using this method has high reliability. EXAMPLES The present invention will be specifically described below with reference to Examples and Comparative Examples, but the present invention is not limited to the Examples below. In addition, in the following examples, all parts indicate parts by weight. Examples 1 to 5, Comparative Examples 1 and 2 Cresol novolak epoxy resin (softening point 60
°C, hydrolyzable Cl 300ppm, Na, Cl each 1ppm, organic acid content 50ppm, epoxy equivalent 200) 62 parts,
Brominated novolac epoxy resin (Br content 35%,
Epoxy equivalent 286) 7 parts, novolac phenol resin (softening point 80℃, free phenol amount 0.1%,
Organic acid 20ppm, Na, Cl each 1ppm) 31 parts, Sb ₂ O ₃ 10
1.5 parts, carnauba wax, carbon black
2.0 parts, 2-phenylimidazole 0.75 parts, α-
Alumina (purity ( _{Al2O3 amount} ) 99.9%, _Na2O content
0.03% Na ion when extracted with water at 100℃
3ppm, Cl ion 0.5ppm, average particle size 20μm,
Particle content with a particle size of 250μm or more is 0.01
%, particle axis ratio of major axis to minor axis is 1.4) 600 parts and 2.0 parts by weight of the following additives were mixed and kneaded for 8 minutes with heated rolls at 100°C, cooled, and then crushed to form epoxy resin. I got the material. Additive

[ka]

[ka]

[ka]

[ka]

[Chemical] γ-glycidoxypropyltrimethoxysilane (grade name KBM403, manufactured by Shin-Etsu Chemical Co., Ltd.)

[Formula] The properties of the obtained epoxy resin molding material were measured by the following method. The results are shown in Table 1. (a) Spiral flow value: 175℃, using a mold that complies with EMMI standards.
Measured under the condition of 70Kg/cm ² . (b) Method for measuring corrosion rate of aluminum wiring A 14-pin IC designed to examine corrosion of aluminum metal electrodes was molded with an epoxy resin composition by transfer molding, and post-cured at 180°C for 4 hours. A pressure vacuum test was carried out in which this was left in water vapor at 2 atmospheres and 120°C, and the incidence (%) of wire breakage caused by aluminum corrosion after 1000 hours was measured. (c) Moisture resistance in terms of dielectric constant and dielectric loss tangent A disk-shaped molded product with a diameter of 70 mm and a length of 2 mm was produced by transfer molding, and post-cured at 180° C. for 4 hours. After measuring the initial permittivity and dielectric loss tangent of this sample at 1KHz, we conducted a pressure-jerker test in which it was left in water vapor at 2 atm and 120℃, and measured the dielectric constant and dielectric loss tangent after 500 hours. . The results are shown in Table 1.

[Table] Example 6, Comparative Example 3 Crystalline quartz powder (average particle size
32μm, particle amount over 200μm 0.1%, SiO ₂ purity 99.8
An epoxy resin composition was produced in the same manner as in Example 1 and Comparative Example 1 except that %) was used, and its spiral flow and moisture resistance were evaluated. The results are shown in Table 2.

【table】

[Table] From the results in Tables 1 and 2, it is recognized that the moisture resistance of the cured product is significantly improved by blending the organosilicon compound of formula (1).

Claims (1)

[Claims] 1. In an epoxy resin composition containing an epoxy resin, a curing agent, and an inorganic filler, the following general formula
(1) [Formula, R ¹ is an organic group having an epoxy group, R ² ,
R ³ and R ⁴ each represent a hydrogen atom, an alkenyl group, an aryl group, or an aralkyl group, and these may be the same or different. n, m
are respectively 0, 1, 2, or 3, 1≦n+m≦3
It is. ) An epoxy resin composition for semiconductor encapsulation, characterized in that it contains an organosilicon compound represented by: 2. A semiconductor device sealed with a cured product of the composition according to claim 1.