JPH01251744A - Resin-sealed semiconductor device - Google Patents

Abstract

PURPOSE:To obtain a polyimide resin protective film whose close adhesion property with reference to a semiconductor substrate and a sealing resin is excellent which can improve the moisture-proofness remarkably by specifying that 50mol% or higher of a unit of tetracarboxylic acid constituting a polyimide resin is a unit of 3,3',4,4'-benzophenone tetracarboxylic acid. CONSTITUTION:Fifty mol% or higher of a unit of tetracarboxylic acid constituting a polyimide resin is specified as a unit of 3,3',4,4'-benzophenone tetracarboxylic acid. After a polyimide film to be used as a protective film has been formed on a semiconductor substrate in this manner, a sealing resin to be used for the manufacture of a plastic packaged semiconductor device is not specified especially. When, however, the polyimide resin whose close adhesion property especially with reference to an epoxy-based or phenol-based sealing resin is extremely good is used as the protective film, it is possible to restrain the moisture from intruding from an interface and to effectively prevent a metal such as aluminum constituting a circuit of an LSI from being corroded; the reliability of the LSI can be enhanced sharply.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Field of Application) The present invention relates to a resin-sealed semiconductor device, and more specifically to a moisture-resistant material for a semiconductor element protective film for passivation, α-ray shielding, etc. The present invention relates to a resin-sealed semiconductor device using a polyimide resin that has excellent adhesion, workability, etc.

(Prior Art) Elements formed on semiconductor substrates are easily affected by the external environment, so a protective film is provided to maintain reliability. Conventionally, inorganic materials such as silicon dioxide, silicon nitride, and alumina have been used as such protective films. On the other hand, among organic materials, polyimide resins have been widely used in place of inorganic materials in recent years because they have a simple process for forming a protective film and can be stabilized at relatively low temperatures.

For example, JP-A-50-8489 discloses a technique in which a semiconductor substrate is pretreated with a 7-minosilane coupling agent to improve the adhesion of polyimide resin. However, although this method improves the adhesion of polyimide resin at room temperature, if it is exposed to high temperature and high humidity for a long time, the adhesion deteriorates and moisture can enter from the outside world, causing defects in semiconductor devices. There was a problem.

Furthermore, conventional resin-sealed semiconductor devices have a structure in which a protective film made of an inorganic material such as silicon dioxide, silicon nitride, or alumina is formed on a semiconductor substrate, and the device is further sealed with an epoxy resin composition or the like. There is. However, sealing resins such as epoxy resins have the property of transmitting moisture, and as the element pellet becomes larger, cracks occur in the protective film due to the difference in thermal expansion coefficient between the sealing VI4 resin and the semiconductor substrate. Therefore, corrosion of wiring patterns made of aluminum or the like has been observed due to the intrusion of moisture. As a countermeasure, a polyimide protective film is further formed on the above-mentioned protective film.

This polyimide resin protective film is required to have good adhesion to both the semiconductor substrate (protective material made of inorganic material) and the sealing resin, moisture resistance, and low stress properties. however.

Conventional polyimide resins have not been able to meet these performance requirements and have been unable to ensure the reliability of semiconductor devices.

(Problems to be Solved by the Invention) The present invention has been made to solve the above problems, and has excellent adhesion to a semiconductor substrate and a sealing resin, significantly improved moisture resistance, and furthermore, a large pellet. An object of the present invention is to provide a resin-sealed semiconductor device using a polyimide resin as a protective film, which can prevent cracks from occurring in the sealing resin.

[Structure of the Invention (Means and Effects for Solving Problems)] The resin-sealed semiconductor device of the present invention has a structure in which tetracarboxylic acid units and diamine units are formed as a protective film on the surface of a semiconductor substrate on which an element is formed. In a resin-sealed semiconductor device coated with a polyimide resin made of a condensation polymer and further sealed with a molding material resin, 5 of the tetracarboxylic acid units constituting the polyimide resin are used.
It is characterized in that it contains 0 mol% or more of Ka33',4,4°-benzophenonetetracarboxylic acid units.

The present invention will be explained in more detail below.

In the present invention, examples of the tetracarboxylic acid units constituting the polyimide resin include pyromellitic dianhydride, 2,3. 3',4'-benzophenonetetracarboxylic dianhydride, 2,3,3',4'-benzophenonetetracarboxylic dianhydride, 3'3'
, 4.4'-biphenyltetracarboxylic dianhydride.

Bis(3,4-dicarboxyphenyl)methanihydride, 2,2-bis(3",4'-dicarboxyphenyl)
Propani anhydride, 2,2-bis(3',4'-dicarboxyphenyl)hexafluoropropani anhydride, bis(3,4-dicarboxyphenyl)sulfone dianhydride,
Bis(3,4-dicarboxyphenyl)dimethylsilane dianhydride, bis(3,4-dicarboxyphenyl)tetramethyldisiloxane dianhydride, 1,4,5°8-naphthalenetetracarboxylic dianhydride, 2,3,6゜7-
Examples include naphthalene tetracarboxylic dianhydride and butane tetracarboxylic dianhydride.

As tetracarboxylic dianhydride, 3.3', 4゜4
'-benzophenone tetracarboxylic dianhydride and 1
One or more types selected from the above group are used.

In the present invention, examples of diamine units constituting the polyimide resin include lin-phenylene diamine, p-phenylene diamine, 2,4-tolylene diamine, 3,3
'-Diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 3,4-diaminodiphenyl ether, 3,3°-diaminodiphenyl sulfone, 4,4
°-Diamino diphenyl sulfone, 3゜4゜-diaminodiphenylsulfone, 3,3-diaminodiphenylmethane, 4,4-diaminodiphenylmethane, 3.4゛-diaminodiphenylmethane, 4,4゜-diaminodiphenyl sulfide, 3,3゜-diaminodiphenylketone,
4,4°-diaminodiphenylketone, 3.4°-diaminodiphenylketone, 2,2′-bis(p-aminophenyl)propane, 2,2°-bis(p-aminophenyl)hexafluoropropane, x , 3-his (m-aminophenoxybenzene), 1.3-bis (p-aminophenoxybenzene), 1.4-his (p-aminophenoxybenzene), 4-methyl-2゜4-his (p
-aminophenyl)-1-pentene, 4-methyl-2,
4-bis(p-7minophenyl)-2-pentene, 1.
4-bis(α,α-dimethyl-p-aminobenzyl)benzene, imino-di-p-phenylenediamine, 1.
5-diaminonaphthalene, 2,6-diaminonaphthalene, 4-methyl-2,4-bis(p-aminophenylpentane), 5(or 8)-amino-1-(p-7minophenyl)-1,3, 3-trimethylindane, bis(p
-7minophenyl)phosphine oxyto, 4,4'-diaminoazobenzene, 4,4°-diaminodiphenylurea, 4,4°-bis(p-aminophenoxy)biphenyl, 2,2-bis(p-(p' -7minophenoxy)phenyl]propane, 2,2-bis(p-(or-7minophenoxy)phenyl]benzophenone, 4.4'-
Bis(p-aminophenoxy)diphenylsulfone, 4
,4°-bis[p-(α,α-dimethyl-p′-aminobenzyl)phenoxifbenzophenone, 4.4′-
Bis[p-(α,α-dimethyl-p-aminobenzyl)
Phenoxyfudiphenyl sulfone, bis(4-7minophenyl)dimethylsilane, bis(4-aminophenyl)
Aromatic diamines such as tetramethyldisiloxane and bis(p-aminophenyl)tetramethyldisiloxane can be mentioned. In addition, the hydrogen atom of the aromatic nucleus of these aromatic diamines is a chlorine atom, a fluorine atom, a bromine atom,
The compound may be substituted with at least one substituent selected from the group such as methyl group, methoxy group, cyano group, and phenyl group.

In addition to the above-mentioned aromatic diamines, examples of diamines include 3,3°-dihydroxy-4°4-diaminobiphenyl, 3,3°-diamino-4,4-dihydroxybiphenyl, and 2,2-dihydroxy-4,4-diaminobiphenyl. bis(3-hydroxy-
4-aminophenyl)hexafluoropropane, 2.2-
Bis(4-hydroxy-3-7minophenyl)hexafluoropropane, 2-(3-hydroxy-4-aminophenyl)-2-(4-hydroxy-3-7minophenyl)hexa20propane, bis(γ-amino propyl)
Tetramethyldisiloxane, 1,4-bis(γ-aminopropyldimethylsilyl)benzene, bis(4-7minobutyl)tetramethyldisiloxane, bis(γ-7minopropyl)tetraphenyldisiloxane, (wherein is a positive number from 2 to 12).

As the diamine, one or two selected from the above group
More than just species are used.

In the present invention, 50 mol% or more of the tetracarboxylic acid units constituting the polyimide resin are 33', 4,4°-benzophenone tetracarboxylic acid units because 33", 4.4 of the tetracarboxylic acid units are A polyimide resin containing less than 50 mol% of '-benzophenone tetracarboxylic acid units has poor adhesion to the insulating film and sealing resin, low moisture resistance, and is difficult to improve the reliability of resin-encapsulated semiconductor devices. This is because it cannot be done.

In order to further improve the reliability of the resin-sealed semiconductor device of the present invention, it is desirable that 2 to 15 mol% of the diamine units constituting the polyimide resin be silicone-containing diamine units.

Polyamic acid, which is a precursor of the polyimide resin according to the present invention, can be synthesized by subjecting a tetracarboxylic dianhydride and a diamine to a polycondensation reaction in an organic solvent. At this time, the organic solvent used is, for example,
N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, N-methyl-(-caprolactam, γ-butyrolactone, sulfolane, N,N,N',N'-tetramethylurea, Examples include hexamethylphosphoramide.

In this reaction, the reaction conditions are as follows: The ratio of tetracarboxylic dianhydride and diamine is such that the equivalent ratio is approximately 1:1.
The reaction temperature is in the range of -10 to 50°C, and the reaction time is in the range of 10 minutes to 20 hours.

The polyamic acid produced under the above conditions is easy to work with in the process of applying it to the substrate, can form a film that maintains sufficient physical strength when applied to the substrate, and can be coated with an alkali such as hydrazine. It is desirable to have a molecular weight that facilitates pattern processing of a polyamic acid film or a polyimide film. From this point of view 0.5g
Polyamic m/N-methyl-2- of yaIB degree
Logarithmic viscosity of pyrrolidone solution at 30°C is 0.4 to 1
．． It is desirable that it be 0 dl/g, particularly preferably in the range of 0.5 to 0.9 dl/g. This is because if the logarithmic viscosity of the polyamic acid solution is less than 0.4 dl/g, a film with sufficient physical strength cannot be formed;
．． This is because if it exceeds 0 dl/g, it becomes difficult to handle the polyamic acid solution in the coating process, resulting in poor workability, and the patterning properties of the polyamic acid film or polyimide film tend to be poor.

In order to produce a polyamic acid in which the logarithmic viscosity of the polyamic acid solution falls within the above range, monofunctional amino compounds such as aniline and p-aminophenol, or dicarboxylic acid anhydrides such as phthalic anhydride and maleic anhydride have a molecular weight of It can be used as a regulator.

After applying the polyamic acid solution synthesized as above to the substrate, the solvent is removed by heating and drying, and the obtained polyamic acid film is heated to 100 to 400°C to cause a cyclization reaction. A polyimide resin according to the present invention is manufactured.

Furthermore, after forming a polyimide film as a protective film on a semiconductor substrate as described above, the sealing resin used when manufacturing a resin-sealed semiconductor device is not particularly limited, and any known epoxy resin may be used. A resin composition can be used. In addition, in order to reduce the stress of the epoxy sealing resin cured with phenol novolac resin, we have developed a silogysan modified phenol novolac epoxy resin lIM (Japanese Unexamined Patent Publication No. 58-214
No. 17), alkylphenol modified phenol noporac epoxy resin (Japanese Unexamined Patent Publication No. 1982-30820)
Modified epoxy resin compositions such as the following may also be used.

The most common method for this sealing is low-pressure transfer molding, but injection molding, compression molding,
Sealing by casting or the like is also possible. Note that during these moldings, it is desirable that the curing temperature of the epoxy resin is 150°C or higher.

The resin-sealed semiconductor device of the present invention includes SiO□, PSG
(phosphosilicate glass), SiNx, and other passivation films, and especially epoxy or phenolic sealing resins, is used as the protective film, so moisture from the interface It is possible to effectively prevent the corrosion of metals such as aluminum that form the LSI circuit by preventing the intrusion of the metal, resulting in a significant improvement in the reliability of the LSI.

(Example) Hereinafter, the present invention will be specifically explained based on Examples.

Example 1 29.18 g (0,089 mol) of 3,3',4,4°-benzophenonetetracarboxylic dianhydride and pyromellitic acid were placed in a reaction flask equipped with a stirring cup, thermometer, and dropping funnel. 8.54 g (0.03 mol) of dianhydride, 0.3 Ei g (0.0024 mol) of phthalic anhydride, and 150 g of N-methyl-2-pyrrolidone were charged, thoroughly stirred, and cooled to 0°C. The suspension was maintained at 0°C and 4.4'-diaminodiphenyl ether22. Hg
(0,113 mol) and bis(γ-7 minoprovir)
Tetramethyldisiloxane 1.84 g (0,007
A solution of 100 g of N-methyl-2-pyrrolidone dissolved in 100 g of N-methyl-2-pyrrolidone was gradually added dropwise from the dropping funnel. After completion of the addition, stirring was continued at 0 to 15° C. for 6 hours to synthesize polyamic acid. 0.5g/dl from this polyamic acid solution
Polyamic Ugly/N-methyl-2-pyrrolidone solution with a concentration of ) Polyamic acid was synthesized using the raw material composition shown in Table 1 in the same manner as in Example 1, and its logarithmic viscosity was measured.

In Examples 2 to 9 and Comparative Example 1.2, the reaction solvent N,N-dimethylacetamide was used in such a range that the concentration of the resulting polyamic acid was 16 to 18 weight.

Further, the abbreviations used in Table 1 will be explained below.

PMDA: Pyromellitic dianhydride BTDA: 3,3', 4,4-benzophenonetetracarboxylic dianhydride BPOA: 3,3', 4,4-biphenyltetracarboxylic dianhydride ODA: 4,4 °-Diaminodiphenyl ether D
PE: 3,4'-diaminodiphenyl ether D
DS: 4,4'-diaminodiphenylsulfone TP
E-Q: 1,4-bis(4-aminophenoxy)benzene BAPP: 2,2-bis[4-(4-aminophenoxy)phenyl]propane TSL: Bis(γ-aminopropyl)tetramethyldisiloxane or higher Polyimide films were created using the polyamic acid solutions synthesized in Examples 1 to 9 and Comparative Example 1.2, and the following evaluations were performed.

■Adhesion with PSG (phosphosilicate glass) film On the silicon wafer on which the PSG film has been formed, a polyamic acid solution is applied using a spin code method, and a 2 mm + square P
Prepare a silicon chip with SG film, dry at 90°C for 30 minutes, dry at 150°C for 30 minutes, and dry at 250°C for 1 hour.
Samples immediately after fabrication (Ohr) in which a polyimide film with a thickness of about 5 μm was formed by heat treatment at 0°C for 30 minutes, and after being left in water vapor at 120°C and 2.2 atm in a pressure cooker for 100 hours. The shear fracture strength of a 2 mm square chip was measured for the sample.

■Adhesion with epoxy resin for semiconductor encapsulation A polyamic acid solution was applied by a spin code method onto a silicon wafer on which a PSG film was formed, and dried at 90°C for 30 minutes.
30 minutes at 0°C, 1 hour at 250°C and 30 minutes at 350°C.
Next, this silicon wafer with a polyimide film was heat-treated for 10 minutes and then molded into a size of 10 m + 30 mm, and molded using a low-pressure transfer molding machine using epoxy resin for semiconductor encapsulation (KE-3007S, trade name manufactured by Toshiba Chemical Co., Ltd.). A 3+sm square sealing resin was formed on the silicon wafer under molding conditions of 175° C. and 80 kg/ca for 2.3 minutes. Similarly to ■, the sample immediately after preparation (Ohr),
The shear fracture strength of the sealing resin was measured for the sample after being left in water vapor at 120° C. and 2.2 atm in a pressure cooker for 100 hours.

These results are also listed in Table 1.

[Effects of the Invention] As detailed above, the resin-sealed semiconductor device of the present invention has the following effects:
Since it uses polyimide resin that has significantly improved adhesion to insulating films such as PSG films and sealing resins, it has high moisture resistance 1, which is required for surface mounting as devices become more highly integrated and substrates become larger. High reliability can be achieved by
Its industrial value is extremely large.

Applicant's agent: Patent attorney Takehiko Suzue

Claims (1)

[Claims] In a resin-sealed semiconductor device in which the surface of a semiconductor substrate on which an element is formed is coated with a polyimide resin made of a condensation polymer of tetracarboxylic acid units and diamine units as a protective film, and further sealed with a molding material resin, the above-mentioned 50 mol% or more of the tetracarboxylic acid units constituting the polyimide resin are 3
1. A resin-sealed semiconductor device comprising a 3', 4, 4'-benzophenone tetracarboxylic acid unit.