JPH0675380A - Polyimide pattern forming method - Google Patents

Abstract

PURPOSE:To facilitate the pattern forming without requiring the photolithographic technique by applying a polymer solution comprising a polymer and a compound contg. an unsaturated bond and an amino group or a quaternized salt on a substrate. CONSTITUTION:The polymer solution comprising the polymer having the structural unit represented by the formula and the compound contg. an unsaturated bond and an amino group or a quaternized salt is applied on the substrate. This substrate is pre-baked, then coated on its prescribed part with an electron donor and developed by using a solvent. Thereafter the substrate is heat-treated to convert the pattern material into polyimide. In the formula, R<1> is a trivalent or quadrivalent organic group having at least 2 carbon atoms; R<2> is a divalent organic group having at least 2 carbon atoms; R<3> is hydrogen, an alkali metal ion or an ammonium ion; (n) is 1 or 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a polyimide pattern, and more particularly to a method for forming a polyimide pattern without using a photolithography technique.

[0002]

2. Description of the Related Art Since polyimide has excellent electrical characteristics and heat resistance, it is widely used in the electrical industry as a surface protective film and an interlayer insulating film for semiconductor elements and substrates on which they are mounted. When used for such purposes, the polyimide is usually patterned to provide the required electrical wiring.

As a method for forming a pattern of polyimide for this purpose, a method of etching polyimide with a strong organic alkali such as hydrazine using a negative resist as a mask (for example, JP-A-53-49701) and a positive resist as a mask are used. A method of etching a film that is not completely polyimide with a weak organic alkali at the same time as developing a positive resist (eg, RADine-Hart, et al.
Br.Polym.J.3,222 (1971)), a method of imparting photosensitivity to polyimide and irradiating the polyimide itself with light to obtain a pattern (for example, Japanese Patent Publication No. 59-52822).

However, the conventional pattern forming method requires an expensive photolithography apparatus. Therefore, when fine pattern processing is not required, it is uneconomical, so that the range of application of polyimide is limited, which hinders the promotion of use of polyimide.

[0005]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a polyimide pattern forming method which can easily perform pattern processing without the above-mentioned drawback, that is, the method by photolithography. is there.

[0006]

The object of the present invention is as follows.
(1) A polymer (A) having a structural unit represented by the general formula [1],

[Chemical 2] (However, R ¹ is a trivalent or tetravalent organic group having at least 2 or more carbon atoms, R ² is a divalent organic group having at least 2 or more carbon atoms, R ³ is hydrogen or an alkaline metal ion. Or represents an ammonium ion, n is 1
Or 2. ) A step of applying a polymer solution containing an unsaturated bond and a compound (B) containing an amino group or a quaternized salt thereof on a substrate, (2) a step of prebaking the substrate, (3) a predetermined on the substrate A step of applying an electron donor to the portion of (4)
And a step (5) of subjecting the substrate to heat treatment to imidize the substrate, and a step of developing with a solvent.

The polymer (A) having the structural unit represented by the general formula [1] in the present invention has the structure represented by the general formula [1], and has an imide ring or the like by heating or an appropriate catalyst. Other examples include polymers that can be a polymer having a ring structure (hereinafter referred to as a polyimide-based polymer).

In the above general formula [1], R ¹ is at least 2
It is a trivalent or tetravalent organic group having one or more carbon atoms. From the heat resistance of the polyimide-based polymer, R ¹ preferably has a structure in which the bond with the carbonyl group of the polymer main chain is directly formed from the aromatic heterocycle. Therefore, R ¹ is preferably a trivalent or tetravalent group containing an aromatic ring or an aromatic heterocycle and having 6 to 30 carbon atoms.

Specific preferred examples of R ¹ include pyromellitic acid residue, 3,3 ', 4,4'-benzophenone tetracarboxylic acid residue, 3,3', 4,4'-biphenyltetracarboxylic acid residue. Acid residue, 2,2-bis (3,4-dicarboxylphenyl) hexafluoropropane residue,
Examples thereof include, but are not limited to, 3,3 ′, 4,4′-diphenyl ether tetracarboxylic acid residue and the like.

In the polymer (A), R ¹ is ^one of these
It may be composed of one kind or a copolymer composed of two or more kinds.

In the above general formula [1], R ² is at least 2
It is a divalent organic group having one or more carbon atoms. Similar to R ¹ , in view of the heat resistance of the polyimide-based polymer, R ² preferably has a structure in which the bond with the carbonyl group of the polymer main chain is directly formed from the aromatic ring. Therefore, R ² is preferably a divalent group containing an aromatic ring or an aromatic heterocycle and having 6 to 30 carbon atoms.

Preferred specific examples of R ² are 4,
4'-diaminodiphenyl ether residue, 4,4'-diaminodiphenylmethane residue, 4,4'-diaminodiphenyl sulfide residue, 4,4'-diaminodiphenyl sulfone residue, paraphenylenediamine residue, metaphenylenediamine residue Groups, benzidine residues and the like, but are not limited thereto.

The polymer (A) has R ² of 1 of these.
It may be composed of one kind or a copolymer composed of two or more kinds.

Further, in order to improve the adhesiveness of the polyimide polymer, it is possible to copolymerize an aliphatic group having a siloxane bond as R ² within a range that does not lower the heat resistance. Preferred specific examples include 1,3-
A bis (3-aminopropyl) tetramethyldisiloxane residue may be mentioned.

In the above general formula [1], R ³ is hydrogen, an alkali metal ion or an ammonium ion, and n is 1
Or 2.

The polymer (A) may be composed of only the structural unit represented by the general formula [1], or may be a copolymer or blend with another structural unit.
In that case, 90 mol% of the structural unit represented by the general formula [1]
It is preferable to contain the above. The kind and amount of the structural unit used for the copolymerization are preferably selected within a range that does not significantly impair the heat resistance of the polyimide-based polymer obtained by the final heat treatment.

Specific examples of the polymer (A) include pyromellitic dianhydride and 4,4'-diaminodiphenyl ether, 3,3 ', 4,4'-benzophenone tetracarboxylic dianhydride and 4,4'. ′ -Diaminodiphenyl ether, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride and 4,4′-diaminodiphenyl ether, pyromellitic dianhydride and 3,3′- (or 4,4 ′)
Diaminodiphenyl sulfone, pyromellitic dianhydride and 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride and 3,3 ′-(or 4,4 ′) diaminodiphenyl sulfone, 3,3 ′, 4,4'-benzophenone tetracarboxylic acid dianhydride and 3,3 '-(or 4,4') diaminodiphenyl sulfone, 3,3 ',
4,4'-biphenyltetracarboxylic acid dianhydride and 3,
3 ′-(or 4,4 ′) diaminodiphenyl sulfone, pyromellitic dianhydride and 4,4′-diaminodiphenyl sulfide, 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride and 4, 4'-diaminodiphenyl sulfide, 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride and 4,4'-diaminodiphenyl sulfide, 3,3', 4,4'-benzophenonetetracarboxylic dianhydride Thing and paraphenylenediamine,
3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride and paraphenylenediamine, pyromellitic dianhydride and 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride and paraphenylenediamine , Pyromellitic dianhydride and 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride and paraphenylenediamine,
3,3 ', 4,4'-diphenyl ether tetracarboxylic acid dianhydride and 4,4'-diaminodiphenyl ether, 3,3', 4,4'-diphenyl ether tetracarboxylic acid dianhydride and paraphenylenediamine, pyromerit Polyamic acid synthesized from acid dianhydride, 4,4′-diaminodiphenyl ether, bis (3-aminopropyl) tetramethyldisiloxane, etc. is preferably used.

As the compound (B) containing an unsaturated bond and an amino group or a quaternized salt thereof, a compound containing a carbon-carbon double bond and an amino group or a quaternized amino group in one molecule is used. . Alternatively, these quaternized salts and the like are preferably used.

Preferred specific examples include dimethylaminoethyl methacrylate, dimethylaminoethyl acrylate, diethylaminoethyl methacrylate, diethylaminoethyl acrylate, vinyl pyridine, dimethylaminopropyl methacrylamide, N-methylol acrylamide and dimethylallylamine. It is not limited to these.

From the viewpoint of performance, an amino compound having an acrylic group or a methacrylic group as an unsaturated group is particularly desirable.

In the compound (B), when the amino group is not quaternized, R ^{3 in the} general formula [1] is preferably combined with the hydrogen polymer (A). When the amino group is quaternized, it is preferable to combine R ³ of the general formula [1] with a polymer (A) of an alkali metal ion or an ammonium ion.

The compound (B) is preferably mixed with the polymer (A) in an amount of 0.05 times the equivalent of all the carboxyl groups (or salts thereof) of the polymer (A), more preferably 0.3. ~ 2 equivalents. If the amount of the compound (B) is too small, the pattern holding property tends to deteriorate, and if it is too large, the allowable range of development conditions such as development time and temperature may be narrowed.

The polymer solution in the present invention contains the above-mentioned polymer (A) and compound (B). The solvent used for the polymer solution is preferably a polar solvent from the viewpoint of polymer solubility, and particularly preferably an aprotic polar solvent. As the aprotic polar solvent, N-methyl-2
-Pyrrolidone, N, N-dimethylformamide, N, N
-Dimethylacetamide, dimethylsulfoxide, hexamethylphosphorotriamide, γ-butyrolactone, dimethylaminoacrylamide and the like are preferably used.

Since the solution of the photosensitive polyimide precursor is prepared by mixing the polymer (A) and the compound (B) of the present invention, the work of the present invention is performed in a dark place or under a yellow light or a red light. It is preferable to carry out.

In the present invention, first, the polymer solution is applied onto a substrate. As the substrate, a semiconductor substrate such as a silicon wafer, a ceramics substrate such as alumina, a metal substrate such as aluminum, iron and chromium, a glass substrate,
A plastic substrate or the like is used.

As a coating method, spin coating using a spinner, spray coating using a spray coater, dipping, printing, roll coating and the like can be used. The coating film thickness can be adjusted by the coating means, the solid content concentration of the solution, the viscosity, etc., but usually the film thickness after drying is 1
It is applied so as to be in the range of ˜100 μm.

The substrate coated with the polymer solution is prebaked to dry the solvent. This prebaking can be performed by a known method using a circulating oven, a hot plate, or the like. As the temperature range of this step, 50 to 120 ° C. is preferable, in the case of a circulation oven, a range of 50 to 100 ° C. for 10 minutes to 3 hours, and in the case of a hot plate, a range of 60 to 120 ° C. and 1 to 30 minutes. Is more preferable. If the amount is out of this range, there is a possibility that all may be dissolved or all may not be dissolved during development processing.

Next, a solution of the electron donor is applied to a predetermined portion on the substrate after the above drying. The predetermined portion is a portion that should be finally left as polyimide,
For example, it is a portion where it is necessary to insulate and protect electronic components such as a substrate and a semiconductor element. It is preferable that the resolution of the predetermined portion is configured by a pattern such as a straight line, a curved line, a triangle, a quadrangle, a circle having a line width larger than 10 μm, or a combination thereof. If the line width is narrower than this, problems such as inability to resolve each line occur, which is not preferable. In the present invention, the minimum line width is preferably 10 μm, more preferably 50 μm, and further preferably 100 μm or more.

As the electron donor, known ones can be used as long as they act as an electron donor. For example,
Bis (ethylenedithio) tetrathiafulvalene, tetrakis (dimethylamino) ethylene, tetrakis (methylthio) tetrathiafulvalene and tetrathiafulvalene are preferably used. In the present invention, it is preferable that the electron donor is dissolved in an ether solvent such as tetrahydrofuran or dioxane, an alcohol solvent such as methanol or ethanol, a halogen-containing hydrocarbon solvent such as chloroform or methylene chloride, and used. . Examples of the method of applying the solution of the electron donating agent include a method of printing on a predetermined portion, coating with a brush or the like, or a method of exposing a necessary portion with a mask and spraying.

After the treatment with the electron donating agent, if necessary, a heat treatment may be performed to further enhance the effect of the electron donating agent. The temperature range at this time is 50 to 1
20 ° C. is preferred.

After that, development is carried out with a solvent to wash away unnecessary portions. As the solvent, a solvent such as N-methyl-2-pyrrolidone, N, N-dimethylacetamide, N, N-dimethylformamide, which is a good solvent for polymers, alone or in methanol, ethanol, isopropanol, butyl acetate, ethyl acetate, A mixture of solvents such as benzene, toluene, xylene and acetonitrile can be preferably used. As such a solvent, those commercially available as a photosensitive polyimide developer can be used. Specific examples thereof include DV-145, DV-505, DV-605 manufactured by Toray Industries, Inc. and A-145 manufactured by Asahi Kasei Corporation.

The developing step for washing away unnecessary portions can be carried out by a method such as immersing in the above solution, immersing while applying ultrasonic waves, or spraying. As described above, the required pattern of the polyimide precursor can be obtained.

After that, the substrate is heat-treated to convert the polyimide precursor into a perfect polyimide to obtain a polyimide pattern. This step is usually performed in an oven, a hot plate, a furnace, or the like. The temperature range is from 200 to
500 ° C. is preferred.

The method for forming a pattern of polyimide of the present invention is a known application using polyimide such as a semiconductor element, a mounting substrate, a liquid crystal display element, a surface protective film for a line sensor, an insulating film, a protective structure for an aircraft or an automobile. Can be used for

[0035]

EXAMPLES The present invention will be specifically described below with reference to examples.

Examples 1 to 6 and Comparative Examples 1 and 2 <Polymerization of polymer>4,4'-diaminodiphenyl ether 2 was placed in a four-necked flask equipped with a thermometer and a nitrogen inlet tube.
Add 0.0g, N-methyl-2-pyrrolidone 150g
Dissolve in. 21.0 g of pyromellitic dianhydride was added thereto together with 30 g of N-methyl-2-pyrrolidone at once, and the mixture was vigorously stirred for 1 hour in an ice bath. Then, the temperature of the bath was raised to 50 ° C. and the reaction was carried out for 3 hours to obtain a solution of the polyimide precursor (a).

4,4'-diaminodiphenyl sulfide 2 was placed in a 4-necked flask equipped with a thermometer and a nitrogen inlet tube.
Put 1.6g, 180g N-methyl-2-pyrrolidone
Dissolve in. 32.0 g of benzophenone tetracarboxylic acid dianhydride was added to N-methyl-2-pyrrolidone 50
g at once and stirred vigorously in an ice bath for 1 hour. Then, the temperature of the bath was raised to 50 ° C. and the reaction was carried out for 3 hours to obtain a solution of the polyimide precursor (b).

<Preparation of Pattern Processing Solution> To 100 g of the polyimide precursor (a) or (b) solution, an amino compound having an unsaturated bond equivalent to the carboxyl group of the polyimide precursor was added to obtain a pattern processing solution. It was The amino compounds used are shown in Table 1.

<Pattern Processing> The above pattern processing solution was spin-coated on a 4-inch silicon wafer by using SCW-636 type manufactured by Dainippon Screen Mfg. Co., Ltd. This was placed in an oven at 80 ° C. for 1 hour and dried.
The film thickness at this time was 10 μm.

A line width of 100 μm made of aluminum foil
Was applied, and a 3% isopropanol solution of an electron donor was spray-treated using a sprayer. The electron donor used is shown in Table 2. After this, 80 ℃
Was processed in the oven for 10 minutes.

After the completion of the treatment, the untreated portion was dissolved using a developer for photosensitive polyimide DV-605 manufactured by Toray Industries, Inc. After this, the film thickness of the treated portion was measured and divided by the initial film thickness to calculate the residual film rate. The higher the residual film rate, the better the performance. At the same time, the line width of the pattern was measured. The closer this value is to 100 μm, the better.

Next, treatment was carried out at 200 ° C. and 400 ° C. for 1 hour each to obtain a polyimide pattern. The results are shown in Table 3.

[0043]

[Table 1]

[Table 2]

[Table 3] Example 7 To 100 g of the polyimide precursor solution (a), 15 g of dimethylaminoethyl methacrylate was added and well stirred to obtain a pattern processing solution.

SCW-6 manufactured by Dainippon Screen Mfg. Co., Ltd. was applied with the above pattern processing solution on a 4-inch silicon wafer.
Spin coating was performed using a 36 type. This was placed in an oven at 80 ° C. for 1 hour and dried. The film thickness at this time is 10
was μm.

Subsequently, a 3% isopropanol solution of tetrathiafulvalene was applied in a straight line with a line width of 1 mm using a brush.

After coating, the untreated portion was dissolved using a developer for photosensitive polyimide DV-605 manufactured by Toray Industries, Inc.
After that, the film thickness of the treated portion was measured and divided by the initial film thickness to calculate the residual film ratio, which was 80%. Also,
The line width was 1 mm.

Next, treatment was carried out at 200 ° C. and 400 ° C. for 1 hour each to obtain a polyimide pattern.

Claims (1)

[Claims] 1. A polymer (A) having a structural unit represented by the general formula [1]: (However, R ¹ is a trivalent or tetravalent organic group having at least 2 or more carbon atoms, R ² is a divalent organic group having at least 2 or more carbon atoms, R ³ is hydrogen or an alkaline metal ion. Or represents an ammonium ion, n is 1
Or 2. ) A step of applying a polymer solution containing an unsaturated bond and a compound (B) containing an amino group or a quaternized salt thereof on a substrate, (2) a step of prebaking the substrate, (3) a predetermined on the substrate A step of applying an electron donor to the portion of (4)
A method of forming a pattern of polyimide, comprising: a step of developing with a solvent; and (5) a step of subjecting the substrate to a heat treatment to imidize.