JPS6086018A - Silicone resin - Google Patents

Abstract

PURPOSE:To produce an SiO2 film free from strain and pinholes, by the thermal decomposition of a silicone resin soluble in a specific solvent and composed of a silanol-terminated polydihydrogen siloxane or a silyl-terminated polydihydrogen siloxane having a specific composition. CONSTITUTION:An SiO2 film having excellent adhesivity and high electrical resistance, and free from the strain or pinholes caused by the organic groups eliminated by the thermal decomposition of the base resin, is produced by the thermal decomposition of a silicone resin applied to a semiconductor substrate, soluble in a ketone, ether, aromatic hydrocarbon or lower aliphatic alcohol at 20-25 deg.C at a weight ratio of 1:1, and composed of a silanol-terminated polydihydrogen siloxane of the general formula( I ) and having a weight-average molecular weight of 10,000-300,000 or a silyl-terminated polydihydrogen siloxane of the general formula (II) and having a weight-average molecular weight of 10,000-300,000.

Description

TECHNICAL FIELD The present invention relates to silicone resins that form silicon oxide films by thermal decomposition.

Background of the Technology When silicone resin is used as an insulating film in a semiconductor device, it is necessary that the silicon oxide film formed by coating the silicone resin on a substrate and heat-treating the substrate be dense and free from distortion and pinholes.

Prior Art and Problems Conventionally, polydialkoxysiloxane and Tatoeba® have been used as silicone resins to form such silicon oxide films. Lydiethoxysiloxane or polydimethoxysiloxane was used. These silicone resins contain a large amount of organic groups, which are thermally decomposed and scattered, so the resulting silicon oxide insulating film contains pinholes, and the film thickness decreases after thermal decomposition, resulting in distortion. . For example, if the coating film thickness is 03 to 05 μm and thermally decomposed, the film thickness will be 3
It decreases by 0 to 50 inches, and when it is heated in air to 500°C, cracks occur.

OBJECTS OF THE INVENTION An object of the present invention is to provide a silicone resin that is substantially free of organic groups that scatter during heating.

Structure of the Invention The above object of the present invention is to provide a compound having a weight average molecular weight of io, ooo to 300.00 expressed by the general formula HOOI2sIo9H.
Ketones, ethers, aromatic hydrocarbons, etc. consisting of silanol-terminated polydihydrodiene siloxane with
is achieved by silicone resins that are soluble in lower aliphatic alcohols at a temperature of 20-25° C. to a weight ratio of at least 1:1. Examples of solvents include benzene, toluene, methyl isobutyl ketone, methyl ethyl ketone, T.
Typical examples are HF (tetrahydrofuran), ethyl alcohol or methyl alcohol.

Note that this silicone resin can be made into a resin with good stability by silylating the silanol terminal. The terminal silyl group (R,, R2, R3-) Sl- is R4゜R2'
R5 is a hydrogen atom or a lower alkyl group such as methyl or ethyl. The silyl-terminated polyhydrodiene siloxane is soluble in ketones, ethers or aromatic hydrocarbons at temperatures of 20 DEG to 25 DEG C. to a weight ratio of at least 1:1.

Typical bath agents include benzene, toluene, methyl isobutyl ketone, methyl ethyl ketone, and THF.

Production method and properties A dialkoxysilane represented by the general formula H2st(oR)2 (where R represents a monovalent aliphatic hydrocarbon) is used as a starting material and is hydrolyzed to produce dihydroxysilane as shown in the following formula. and subsequent condensation polymerization to produce silanol-terminated dihydrodiene siloxane (hereinafter referred to as PDH8).

H281(OR)2+2H20→H2S1(OH)2+
2ROH, H At this time, 6 points! By setting I〈7, GPC
The weight average molecular weight measured in terms of polystyrene is t
o, ooo to 300,000, and the ketone, ether, aromatic hydrocarbon or lower aliphatic alcohol has a weight ratio of at least 1 at a temperature of 20 to 25°C.
:Dissolve up to 1. If the voice is <6, the 5L-H bond will be decomposed, three-dimensional crosslinking will occur, and the polycondensation reaction will not proceed at pH = 7, and if pi (>7), the 5L-H bond will decompose, resulting in three-dimensional crosslinking and gluing. Glues and becomes insoluble in solvents.

The starting materials are dimethoxysilane (b, p, 38°C) or jetoxysilane (b, p, so~81°C), and a solvent having a higher boiling point than these monomers, such as methyl isobutyl ketone ( b, p.

(117°C) and reacted with a monomer rotation of 3 to 7% by weight. If the amount is much lower than 3, the reaction will be slow and the yield will be low, and if it is higher than 7% by weight, it will be three-dimensionally crosslinked and glued, becoming insoluble in the solvent. Furthermore, the reaction temperatures for hydrolysis and polycondensation are controlled to be no higher than 50°C. 50℃
If you are tall, you will easily become a group and live a long life.

PDH8 of the present invention is considered to have a simple polymer structure, and is a viscous liquid or solid.
It dissolves to a weight ratio of at least 1.1.

If dichlorosilane is used as a starting material, it will hydrolyze to produce polyhydrochloric acid and become strongly acidic, making it difficult to control P1, and the resulting condensation polymer will have a low average degree of polymerization n≦6. However, it cannot be used to form a silicon oxide film because it is insoluble in benzene and cannot be used as a coating solution.

As the silylating agent for PDH8, chlorosilane having an organic group with a small molecular weight is used. For example, when dimethylchlorosilane is used as the silylating agent, dimethylsilyl-terminated PDH8 shown in the following formula is produced.

This silyl-terminated PDH8 can be reacted with a ketone or aromatic hydrocarbon such as benzene, toluene, methyl isobutyl ketone or methyl ethyl ketone, THF at a temperature of 20-25°C.
℃ to a weight ratio of at least 1:1.

It is thought that the PDH8 and silyl-terminated PDH8 of the present invention have small holes for organic groups during thermal decomposition, and have very few distortions and pinholes caused by thermal decomposition.

The weight average molecular weight and solubility of PDH8 prepared using the dialkoxysilane of the present invention as a starting material, and the infrared absorption spectrum, weight average molecular weight, and thermogravimetric analysis of silyl-terminated PDH8 obtained by silylating it are as follows. .

FIG. 1 is an infrared absorption spectrum of dimethylsilyl-terminated PDH8. 5t- for wave number 2100~2250cm-'
) T, 29ffOcm to C-H3,12601 Eng to 8l-CH3,100 (1 to 1150cm to 8
The properties based on 1-0 have been confirmed, and the main skeleton is a siloxane bond, two hydrogen atoms are bonded to a silicon atom,
It was found to have the following structure having a 5i-cu bond at the end.

The weight average molecular weight of CH3HCH3 PDH8 was in the range of 10,000 to 300,000 in terms of polystyrene by GPC method.

If the average molecular weight -i' is less than 10,000, low molecular weight substances will volatilize during heat treatment, resulting in a large weight loss, and the film will become strained, making it unsuitable. ,3
If it is thicker than 00,000, it is unsuitable because it causes three-dimensional crosslinking, tends to cause calcification, and becomes insoluble in solvents.

The molecule i of silyl-terminated PDH8 is believed to be substantially the same as the molecular weight of PDH8.

When this PDH8 is dissolved in benzene, toluene, methyl alcohol, and ethyl alcohol at a temperature of 20 to 25°C, the triethylsilyl-terminated PDH8 is dissolved in benzene, toluene, methyl alcohol, and ethyl alcohol at a weight ratio of at least 1:1. The solubility of methyl isobutyl ketone and methyl ethyl ketone at a temperature of 20 to 25°C was such that both were dissolved at a weight ratio of at least 1:1.

For thermal analysis, the weight of uncured dimethylsilyl-terminated PDH8 was taken as 100, and the heating rate was 5°C/min.
It was heated in a trench at 900°C. The weight change started at 250°C and reached about 110% at 450°C. This is St
This is thought to be due to the decomposition of -H and the addition of oxygen, and it was found that the oxidation was completed at 450°C for about t'8, and thereafter there was no change until the temperature exceeded 800°C (Figure 2).

Use for insulating film A methyl isobutyl ketone solution containing 820% by weight of dimethylsilyl-terminated PDH was placed on silicone Ueno 1 at a temperature of 300%.
Orpm, applied under the conditions of 30 ir and heated at 100°C.
After heating for 30 minutes at
Heated at ℃ for 1 hour. When the coating film thickness was set to 0.6 to 0.7 μm, the change in film thickness was only about 10 cm. Note that no cracks were generated even when heated to 500°C, and it was stable even at 750°C.

Example: Add 100 g of pure water to commercially available jetoxysilane 10I,
Shake well. The fractionated aqueous layer had a - of 5.8, so 10g of the fraction with a boiling point of 80.0 to 80.5°C obtained by precision distillation was washed again with pure water of 100.9. Ha-
=6.6.

Thus AI'i'H jetoxysilane 50.9
Add purified methyl isobutyl ketone 95011 to
While cooling on ice, add 75.9 drops of distilled water at a rate of 1 drop every 5 seconds to perform hydrolytic dealcoholization, continue water cooling for about 30 minutes, and then gradually raise the temperature. The temperature was raised to 35° C., and stirring was continued at this temperature for 2 hours to effect hydrolysis and condensation polymerization. During this time, the reaction was promoted by removing the generated alcohol and water by reducing the pressure in the 50-degree direction. The residual liquid is 550 g of dimethyl isobutyl ketone solution containing approximately 3% PDH8.
Met.

To this PDH8 solution, 39 g of dimethylchlorosilane, which is equivalent to jetoxylan, was added with stirring, and the mixture was heated to 30°C.
Stirring was continued for 0 minutes to complete the silylation. Distilled water 2! was added dropwise at a rate of one drop per second to decompose excess dimethylchlorosilane, which was further washed with water and concentrated under reduced pressure. Five times the volume of acetonitrile was added to the obtained organic layer to precipitate the silyl-terminated PDH8, and the gradient washing with acetonitrile was repeated three times to obtain the dimethylsilyl-terminated PDII as a white powder.
S18N was obtained.

The weight average molecular weight of this silyl-terminated PDH8 was measured as follows.

0.1 g of dimethylsilyl-terminated PDH8 was dissolved in 1011 volumes of tetrahydrofuran to obtain a 1 wt % tetrahydrofuran solution. Using this solution, the molecular weight was measured using the GPC method (glupermeator chromatography) KJ:υ. As a result, weight average molecular weight Mw = 158,000, number average molecular weight MN = 30.200 - dispersity MW/MN
= 5.27.

The average molecular weight of PDH8 itself is considered to be the same as that of silylated PDH8. Each PDH8 was dissolved in benzene, toluene, methyl isobutyl ketone, methyl ethyl ketone, tetrahydrofuran, methyl alcohol, and ethyl alcohol to a weight ratio of at least 1:1 at room temperature (25° C.). In addition, dimethylsilyl non-#PDH8 is at room temperature (2
5° C.) in benzene, toluene, methyl isobutyl ketone, methyl ethyl ketone, and tetrahydrofuran to a weight ratio of at least 1:1.

Next, a 20% by weight bath solution containing purified dimethylsilyl-terminated PDH85, S' in toluene 20.9 was coated on a silicon wafer with a K 3000 ryen to form a coated arm, and this was heated at 100 °C for 30 minutes. , then 450℃
The film was heat-treated for 1 hour to form a silicon oxide film.

The change in film thickness before and after this heat treatment is 0.75μ before curing.
m was only 0.70 μm after curing, and the film was left to stand at 500° C. for 2 hours in air, but no abnormality was observed in the film. As described above, the silicon oxide film had no cracks, no visible minute pinholes, and had an electrical resistance of 5 x 10"Q-cm, and had good insulation properties.

In addition, this cured film has good adhesion to the underlying substrate,
It showed excellent adhesion to a variety of substrates, including silicon, silicon oxide, ordinary glass, phosphosilicate glass, alumina, and aluminum.

Effects of the Invention Applying the silicone resin solution of the present invention to various substrates,
The silicon oxide insulating film formed by heat treatment has the advantage of good adhesion to the substrate, high electrical resistance, and no cracking even when heated to high temperatures.

[Brief explanation of drawings]

FIG. 1 shows a dimethylsilyl-terminated P which is an embodiment of the present invention.
FIG. 2 is an infrared absorption spectrum curve of DH8, and FIG. 2 is a thermogravimetric analysis curve of dimethylsilyl-terminated PDH8, which is an embodiment of the present invention.

Claims (1)

[Claims] 1. Weight average molecular weight Mw expressed by the general formula % is 10,000 to 30
0.000 silanol-terminated polydihydrodiene siloxane, which is soluble in ketones, ethers, aromatic hydrocarbons or lower aliphatic alcohols at a temperature of 20-25°C to a weight ratio of at least 1:1. 2. The weight average molecular weight represented by the general formula (wherein R1, R2+ R3 are hydrogen atoms or lower alkyl groups) is 10,000 to
300,000 to a ketone, ether or aromatic hydrocarbon in a weight ratio of at least 1 at a temperature of 20-25°C.
: Silicone resin that can be dissolved up to 1.