JPS59107522A - Method for formation of polyimide layer having excellent adhesive property on surface of element consisting of silicon containing material - Google Patents

Abstract

PURPOSE:To enable to form a polyimide layer of excellent close-contacting and dampproof properties by a method wherein a specific ratio of diaminosiloxane and non-silicon containing diamine are simultaneously polymerization-reacted with aromatic tetracarboxylic acid dianhydride. CONSTITUTION:The diaminosiloxane as indicated in general formula I and the diamine containing no silicon atom in a molecule are simultaneously polymerization-reacted with aromatic tetracarboxylic acid dianhydride. When performing said polymerization reaction, the mixing ratio of diaminosiloxane is brought within the range of 1-4mol% of the total quantity of diamino compound, and the silicon content contained in final reactant is to be made at 0.5wt% or below, and a siloxane denatured polyimide precursor is obtained. This polyimide precursor is applied to the surface of a semiconductor element. Then, a polyimide layer is formed by performing a high temperature heat treatment. As a result, a polyimide layer of excellent close-contacting and dampproof properties on the surface of element consisting of silicon-containing material can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for forming a polyimide layer with good adhesion on the surface of a substrate made of a silicon-containing material.

Conventionally, polyimide, which has many advantages such as heat resistance, electrical insulation, and mechanical strength, has been used for semiconductor devices.
The use of heat-resistant polymers such as polyamideimide and polyhydantoin has been considered. However, these layers made of heat-resistant polymers have a problem of poor adhesion to substrate surfaces such as silicon wafers and glass.

For this reason, various proposals have been made to improve the adhesion of the heat-resistant polymer layer, one of which is
Regarding imides, there is a method in which diaminosiloxane is used as the diamino compound when synthesizing a polyimide precursor through a polymerization reaction between an aromatic tetracarboxylic dianhydride and a diamino compound. This method uses 3i-0-3i containing RM from diaminosiloxane in the molecular skeleton.
By introducing a bond, the silicon wafer,
The aim is to improve adhesion by having a chemical bond between the silicon atoms of a silicon-containing material such as glass and using this as an active site for adhesion to the silicon-containing material.

However, in the above proposed method, diaminosiloxane is used in a considerable proportion of the diamino compound or as all of the diamino compound, so even if it is possible to improve the adhesion, the moisture resistance of the polyimide layer will be greatly affected. There was a drawback. Furthermore, excessive use of diaminosiloxane was not necessarily desirable in terms of inherent heat resistance, electrical insulation, mechanical strength, etc. Similarly, in the proposed method, there are polyimide precursors synthesized using an excessive amount of diaminosiloxane, and polyimide precursors synthesized using diamines that do not use diaminosiloxane (that is, they do not contain silicon atoms in the molecule). There is also a method of making a mixture with a precursor, but even in this case, the same problem as mentioned above occurs because the silicon content in the mixture is large, and since it is a mixture, it has poor adhesion, moisture resistance, and Other general characteristics tend to vary among KonoFs, and stable performance could not be obtained.From the above point of view, this invention has problems with adhesion to silicon-containing materials or substrate surfaces made of silicon-containing materials. In order to obtain a siloxane-modified polyimide precursor that can form a polyimide layer with good moisture resistance properties, and which can also provide inherent heat resistance, electrical insulation, mechanical strength, etc., extensive research has been carried out.
This was discovered by repeating 1.

That is, this invention provides the following general formula ([, is a divalent organic group, R' is a monovalent organic group, n
is an integer from 1 to 1,000) and cyamine, which does not contain a silicon atom in its molecule, are simultaneously polymerized with an aromatic tetracarboxylic dianhydride. The percentage
In the range of 1 to 4 mol% of the total amount of diamino compounds and Iυ
The method is characterized in that a siloxane-modified polyimide precursor obtained in such a way that the silicon content contained in the Hiiragi reaction product is 0.5% by weight or less is applied, and then subjected to high temperature heat treatment to form a polyimide layer. The present invention relates to a method for forming a polyimide layer with good adhesion on the surface of a substrate made of a silicon-containing material.

As described above, in this invention, the diaminosiloxane used to improve the adhesion of the polyimide layer is necessary and sufficient within the above specified range, and when used in such a proportion, the amount of moist heat in the polyimide precursor increases. Since the number of siloxane bonding parts that are easily broken by decomposition or acid or alkali is extremely small, the moisture resistance of the polyimide layer is not reduced, and the heat resistance, electrical insulation, and mechanical strength inherent to polyimide are improved. I discovered that there is no need to worry about becoming a member.

In the diaminosiloxane represented by the general formula +11 in this invention, the two R1s and each R' in the formula may be the same or different, and a wide variety of conventionally known diaminosiloxanes are included. Typical examples are as follows.

The diamine that does not contain a silicon atom in its molecule (hereinafter simply referred to as silicon-free diamine) used in the invention of father/'/shi6t15 rishi113 shib jis has the following general formula (2); % formula %(2) (R2 is a divalent organic group not containing a silicon atom) It may be the same as or different from R in +1+. Particularly preferred are aromatic diamines, representative examples of which include metaphenylenediamine, paraphenylenediamine, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenyl ether, 2,2
'-Bis(4-aminophenyl)propane, 3,3'-
Diaminodiphenylsulfone, 44'-diaminodiphenylsulfone, 4,4'-diaminodiphenylsulfide, henzidine, henzidine-3,3'-dicarboxylic acid, henzidine-3,3'-disulfonic acid, benzidine-
3-monocarboxylic acid, benzicine-3-monosulfonic acid, 3,3゛-nomethoxyhendicine, para-bis(4
-aminophenoquine) Hensen, Mecoubis(4-aminophenoxy) Hensen, metaxylylenediamine, paraquinlylenediamine, and the like.

In this invention, the aromatic tetracarboxylic dianhydride to be polymerized with a diamino compound consisting of two parts of soaminosiloxane and a silicon-free diamine is represented by the following general formula (3).
It is represented by the formula % (Ar is a tetravalent organic group), and representative examples thereof are as follows. Zunawara, Piromeri.

l dianhydride, 3,3',4,4'-henzofuenonte I
・Lacarboxylic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 2,3,3',4'-
Biphenyltetracarboxylic dianhydride, 2, 3, 6, 7
-Naphthalenetetracarboxylic dianhydride, l.2.5.
6-naphthalenetetracarboxylic dianhydride, 1, 4, 5
・8-Naphthalenetetracarboxylic dianhydride, 2.2'
-bis(3,4-dicarboquinophenyl)propane dianhydride, bis(3,4-dicarboquinophenyl)sulfone dianhydride, 3,4,9,lO-perylenetetracarboxylic dianhydride, bis( 34-Dicarboquinophenyl)ether dianhydride 11)>, 2,2′-bis(2,3-dicarpoquinophenyl)propane dianhydride, l・1′-bis(2,3-nocarpoquinophenyl) Ekunni try<
hydrate, Hensen-1,2,3,4-tel-lacarphone dianhydride, 2,3,6,7-anthracenetetracarboxylic dianhydride, l,2,7,8-phenanthrenetetracarboxylic acid There are dianhydrides, etc.

A particularly suitable aromatic tetracarboxylic dianhydride for this invention is 3,3',4,4'-biphenyltetracarboxylic dianhydride. When this dianhydride is used, the pressure test (hereinafter simply abbreviated as pc'r) can be carried out under a high temperature and high humidity atmosphere, for example at 121°C and 12 atm.
This results in a polyimide layer with even more deformed electrical properties, that is, extremely good moisture resistance. Of course, the moisture resistance can be improved even when other dianhydrides are used.

In this invention, it is necessary to simultaneously polymerize the diaminosiloxane and the silicon-free diamine with the aromatic tetracarboxylic dianhydride. For example, it is not possible to polymerize both diamino compounds separately and then mix them together. ,
This causes variations in adhesion and 11.1 moisture properties, making it impossible to stabilize the quality.In addition, as already mentioned, the diaminosiloxane used at this time is preferably 1 to 4 mol% of the total amount of the diamino compound. must be 3 to 3.5 mol%, and the silicon atom content contained in the polyimide precursor, which is the final reactant, must be 0.5% by weight or less. If none of these quantitative relationships are satisfied, it becomes difficult to achieve both adhesion and moisture resistance. The ratio of the diamino compound consisting of the diaminosiloxane and the silicon-free diamine to the aromatic tetracarboxylic dianhydride is usually equimolar, but if necessary, one may be slightly increased.

The monopolymerization reaction may be carried out by a conventionally known method (IS) in the presence of a general organic solvent in a nitrogen gas stream, usually at a temperature of 60°C or less, particularly preferably at a temperature of 30°C or less, taking into account the polymerization heat generated.
The reaction may be allowed to proceed until a high degree of polymerization is obtained while limiting the temperature to below °C. This degree of polymerization can be conveniently detected by examining the intrinsic viscosity [η] of the reactant.

Examples of organic solvents include methyl-2-pyrrolidone, N-N'-dimethylacetamide, N-N'-dimethylpolamide, N-N'-dimethylsulfoxide, hexamethylphosporamide, etc. Highly polar salt 'A l
i solvent is used. All of these 8 solvents are highly hygroscopic, and absorbed water causes a decrease in molecular weight during polymerization and storage stability, so it is recommended to thoroughly dehydrate with a dehydrating agent before use. good. In addition to these C carriers, toluene, quinolene, henzonitrile, henzene,
A general-purpose solvent such as phenol can also be used in combination. However, the amount used should be within a range that does not reduce the solubility of the polyimide precursor produced.

As shown in the following general formula (4), the polyimide precursor thus obtained by the present invention has a structure in which silicon-free diamine diaminosiloxane and aromatic tetracarboxylic dianhydride are bonded via an amide bond. It is a polymer structure in which the bond positions added to are random, and the polyimide 1
The special advantage is that the precursor molecule 4j'f has a structure in which a very small amount of so I coxane bond is incorporated into NJ'.

p (R1, RZ, R', n and Δr]); As described in 1, rn/n + m = 0.0 t~o, o 4)
! (R1, RZ, R', A r By heat treatment, dehydration, and cyclization, the above-mentioned general i' exhibits poor adhesion to glass.
It is possible to form a layer consisting of a polyimide as shown by s and f51. This polyimide layer has excellent moisture resistance properties, as well as its inherent good heat resistance, chemical resistance, mechanical properties, and excellent electrical properties. It has the advantage that it can be effectively applied to various known uses.

Note that in applications such as forming a polyimide layer on a semiconductor element, contamination with ionic impurities must be avoided when forming polyimide F+AT4. Na
“, K”, Ca2゛, cationic impurity, CE
Care must be taken to avoid lη staining from anionic impurities such as -, especially Na' ions.
should also have an adverse effect on the electrical properties of the conductor. Therefore, during polymerization, both the raw material monomer and the solvent should be sufficiently purified by well-known methods before use. for example,
It is desirable that Na' is 5 PPM or less, preferably IP)) M or less.

Examples of this invention will be described below. In the following, the degree of polymerization (molecule ■1) of the polyimide + III precursor is not shown, but the intrinsic viscosity (η) is used as a parameter.
i, 1lll constant temperature 30±0. It is calculated according to the following formula at o1°C (constant temperature bath).

[η]-βn(t/Lo)/c L: Falling time tO of the polymer solution measured by Uherode viscosity a1; Falling time tO of the solvent measured as above ζ; Polyimide precursor (polymer) concentration (o , 5% by weight) Example 1 500mj with external stirring device, cooling pipe, temperature 91 and nitrogen purging device! Fix the flask on a water bath? . After drying over phosphorus pentoxide for a day and night, and then performing vacuum distillation, 280.90 g of purified N-methyl-2-pyrrolidone was added to the flask, and nitrogen was flushed into the flask.

Next, 0.87 g (0,0035 mol) of bis(3-aminopropyl)tetramethyldisoloxane shown in 2 above was added using a 1 mp microsyringe, and then 4.4'
-diaminodiphenyl ether 19.3g (0,09
65 mol) and stirred until dissolved. 29.4 g (0.1 mol) of 3.3'.4.4'-hyphenylte-1-lacarboxylic acid dianhydride was then gradually added to the mixture under cooling power for 11 hours. The reaction system was stirred while maintaining the temperature at 30'C or less until a transparent and viscous solution was obtained.

The polyimide precursor thus obtained had an intrinsic viscosity of 1.67 and a silicon content of 0.397%. The solution containing the N;
A polyimide layer was formed by heating at 0° C. for 1 hour and at 250° C. for 6 hours. The infrared absorption spectrum of the polyimide layer thus formed is 1780 cm-' and 172 cm-'.
Absorption of <>C=O was observed based on the formation of a 0 cm-'niimi7 do group. The formed Boliimi F layer was strong and had good adhesion to the silicon wafer under normal conditions. It was also found that the adhesiveness was highly improved without peeling even after PCT treatment.

Example 2 Purified N·N'-dimethylace1-amide was used as an N8 medium at 2F! The polyimide precursor 15 A wt% solution was made.

The intrinsic viscosity of the polyimide precursor at this time was 1.81, and the silicon content was 0.396% by weight.

-1. When a polyimide layer was formed on a silicon wafer under the same conditions as in Example 1 using the polyimide precursor solution described above, the toughness and adhesion of the layer were the same as in Example 1. .

Example 3 +a "JJ The amount of N-methyl-2-pyrrolidone used was 237.83 g, and pyromellitic dianhydride was 21.8 g (0°1
A 15% by weight solution of the polyimide precursor was prepared in the same manner as in Example 1, except that mol) was used.

The polyimide precursor thus obtained had an intrinsic viscosity of 1.65 and a silicon content of 0.469% by weight. Contains this precursor? '8 solution was spin-coded in the same manner as in Example 1 and dried at 200°C for 1 hour at 150"C in a hot air dryer.
A polyimide layer was formed by heating at 300° C. for 1 hour and at 300° C. for 1 hour. The formed polyimide layer was strong, had good adhesion both under normal conditions and with PCI, and no peeling from the silicon wafer was observed.

Example 4 The amount of purified N-methyl-2-pyrrolidone used was 295,6
7 g, and 3 as aromatic tetracarboxylic dianhydride.
・3', 4, 4'-henzophenone tetracarboxylic dianhydride (32.2 g < 0.1 mol) and 4, 4'-diaminodiphenylmethane 19.
A 1.5 MM% solution of a polyimide precursor having a culm viscosity of 1.38 and a silicon content of 0.377% by weight was prepared in the same manner as in Example 1, except that 107 g (0,0965 mol) was used. Ta.

When a polyimide F' layer was formed on a silicon wafer'2 using the above polyimide precursor solution under the same conditions as in Example 1, the adhesion of the layer was the same as in Example 1, but after 6 months. It was observed that the tensile strength after time had decreased to 40% of the initial value. Although it was found that the toughness of the film deteriorated over time, it was still strong enough to be used.

Example 5 The amount of purified N-methyl-2-pyrrolidine used was 259,3
6 g, 14.7 g (0.05 mol) of 3,3',4,4'-hyphenyltetracarboxylic dianhydride and pyromellitic dianhydride as aromatic tetracarboxylic dianhydride. 10.9 g (0.05 mol) of the polyimide precursor was used in the same manner as in Example 1 except that 15
A wt% solution was made.

The obtained polyimide precursor had an intrinsic viscosity of 1.52 and a silicon content of 0.430% by weight.

When a polyimide layer was formed on a silicon wafer using the above polyimide precursor solution in the same manner as in Example 3, the toughness and adhesion of the layer were the same as in Example 1.

Comparative Example 1 Use of purified N-methyl-2-pyrrolidone 1iwo280.
07 g, the amount of 4,4'-diaminodiphenyl ether used was 19.9 g (0,0995 mol), bis(3-
Except that the amount of (aminopropyl)tetramethyldisiloxane used was 0.1243g (0,0005 mol).
15% by weight of a polyimide precursor having an intrinsic viscosity of 2.37 and a silicon content of 0.057% by weight in the same manner as in Example 1
I made a solution.

When a polyimide layer was formed on a silicon wafer using this solution under the same conditions as in Example 1, it did not peel off from the silicon wafer under normal conditions, but it peeled off easily with PC'r.

Comparative Example 2 The amount of purified N-methyl-2-pyrrolidone used was 281.8
6 g, the amount of 4,4'-diaminodiphenyl ether used is 18.6 g (0,093 mol), the amount of bis(3-aminopropyl)tetramethyldisiloxane used],
A 15% by weight solution of Boliimi 1-precursor a was prepared in the same manner as in Example 1, except that the amount was 7395 g (0,007 mol).

The polyimide 1' precursor thus obtained had an intrinsic viscosity of 0.80, and had a lower molecular weight than the polyimide precursor obtained in Example 1. Moreover, the silicon content of this precursor was 0.791% by weight.

When a polyimide layer was formed on a silicon wafer using the polyimide precursor thus obtained under the same conditions as in Example 1, the toughness and adhesion of the layer were the same as in Example 1. .

Comparative Example 3 Bis(3-aminopropyl)tetramethyldisiloxane and 4,4'-diaminodiphenyl ether were prepared in Example 3.
After carrying out a polymerization reaction with pyromellitic dianhydride separately in the same proportion as the above, both were mixed to obtain a 15% solution of the polyimide precursor mixture. The intrinsic viscosity of the polyimide precursor obtained from diaminosoloxane is 0.63, the intrinsic viscosity of the polyimide precursor obtained from silicon-free diamine &t, 2. O
It was O. The silicon content in the polyimide precursor mixture was 0.469% by weight.

When a polyimide layer was formed on a silicon wafer using this solution under the same conditions as in Example 3, the adhesion to the silicon wafer was inferior to that in Example 3, and the characteristics did not vary. In some cases, it peeled off easily.

Comparative Example 4 The amount of purified N-methyl-2-pyrrolidone used was 187.5
2 g, 21.8 g (0°1 mole) of pyromellitic dianhydride as the aromatic tetracarboxylic dianhydride, and 10 g of para-phenylenediamine as the silicon-free diamine.
．． 15 of the polyimide precursor was prepared in the same manner as in Example 1, except that 0.87 g (0.0035 mol) of bis(3-aminopropyl)tetramethyldisiloxane was used as diaminosoloxane. A wt% solution was made.

The intrinsic viscosity of this polyimide precursor was 1.58, and its silicon content was 0.594% by weight. The polyimide prepared in this way was prepared as follows: When a layer was formed using the G1 solution in the same manner as in Example 1, the adhesion of the layer was the same as in Example 1.

Next, the polyimide layers obtained in Examples 1 to 5 and Comparative Examples 1 to 4 were tested for adhesion and electrical insulation under the same environmental conditions. The results were as shown in the following table.

The thickness of each polyimide layer is 3 to 50±5μ.
ffJ PI.

As is clear from the above table, Examples 1 to 5 of this invention
It can be seen that the polyimide layer has poor electrical properties and poor adhesion at high temperatures. In addition, especially as aromatic tetracarboxylic dianhydride, 3, 3', 4,
Examples 1 and 2 using 4'-biphenyltetracarphonic dianhydride are similar to Examples 3 to 5 using other dianhydrides.
It can also be seen that both of the above properties, especially the electrical properties at high temperatures, are significantly different from those of the above.

On the other hand, the polyimide layer formed in Comparative Example 1 had no inferior electrical properties, but poor adhesion to the silicon wafer. In addition, although the polyimide layer formed from Comparative Example 2.4 has no problems with adhesion, it has inferior electrical properties under high temperature and high humidity. The measurement result was about 1/100 of the towing rate (volume). Comparative Example 3 is a single layer of polyimide formed from a mixed solution of a silicon-free polyimide precursor and a silicon-containing polyimide precursor, but in this case, even if the total silicon content is within the range of the present invention. It can be seen that good results were not obtained in terms of adhesion and electrical properties under high temperature and high humidity.

Claims (1)

[Claims] The following general formula (R
, is a divalent organic group, R' is a monovalent organic group, and n is 1
In simultaneously polymerizing diaminosiloxane (which is an integer of 1,000 to 1,000) and a diamine that does not contain a silicon atom in the molecule with aromatic tetracarphonic dianhydride, the proportion of the diaminosiloxane used is as follows: Coating a siloxane-modified polyimide precursor obtained in a range of 1 to 4 mol% of the total amount of the diamino compound and such that the silicon content contained in the final reaction product is 0.5% by weight or less, A method for forming a polyimide layer with good adhesion on the surface of a substrate made of a silicon-containing material, the method comprising then performing a high-temperature heat treatment to form a polyimide layer.