JP2000058535A - Manufacture of semiconductor element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor element comprising an insulating film or protective film which, excellent in etching-resistance in a nitric-acid fluoride solution, has less metal ion such as sodium ion that affects on a device. SOLUTION: On a substrate, a film wherein a polyimide precursor composition whose main components are (1) polyamide acid, (2) a compound comprising tertiary amino group, and (3) a colloidal silica is heated is so formed that the surface of substrate is selectively exposed, and the exposed part is etched with nitrohydrofluoric acid, with the heated film used as an insulating film or protective film. Here, the content of sodium ion of the heat-treatment film before etching is 10 ppm or less.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a semiconductor device.

[0002]

2. Description of the Related Art Colloidal silica-containing polyimide is known as a passivation film for a semiconductor device having a high withstand voltage and a large current, for example, a power diode and a thyristor. In such a device, the back surface or a part of the front surface of the semiconductor substrate is subjected to an etching process with hydrofluoric nitric acid or the like in a further post-processing after exposing the substrate surface. Inclusion of colloidal silica improves the resistance to hydrofluoric nitric acid and improves the resistance to peeling of the film from the substrate, but on the contrary, the characteristics of the device deteriorate due to sodium ions contained in the colloidal silica. was there.

[0003]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned drawbacks and does not adversely affect the device after the hydrofluoric / nitric acid treatment step of the substrate, and is preferably used as an element, an insulating film for electrodes and a protective film. Is to provide.

[0004]

According to the present invention, a polyimide precursor composition mainly comprising (1) a polyamic acid, (2) a compound containing a tertiary amino group, and (3) colloidal silica is provided on a substrate. A heat-treated film is formed so that the substrate surface is selectively exposed, the exposed portion is etched with hydrofluoric nitric acid, and a heat treatment before the etching is performed in a semiconductor element using the heat-treated film as an insulating film or a protective film. A method for manufacturing a semiconductor device, characterized in that the film has a sodium ion content of 10 ppm or less.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.

The polyamic acid in the present invention is produced by a condensation reaction between a tetracarboxylic dianhydride and a diamine. A general synthesis method is a method in which a diamine is dissolved in an aprotic polar solvent such as N-methyl-2-pyrrolidone, and then tetracarboxylic dianhydride is added to obtain a viscous solution.

Polyhydroxyamide can be used instead of polyamic acid as a heat-resistant polymer precursor similar to polyamic acid. Such a polyhydroxyamide can be produced by a condensation reaction between a bisaminophenol compound and a dicarboxylic acid. Specifically, dicyclohexylcarbodiimide (D
A method of reacting a dehydrating condensing agent such as CC) with an acid and adding a bisaminophenol compound thereto, or a method of dropping a solution of dicarboxylic acid dichloride into a solution of a bisaminophenol compound to which a tertiary amine such as pyridine is added. is there.

When a polyhydroxyamide is used, a photosensitive agent such as naphthoquinonediazidosulfonic acid ester is added to a solution of the polyhydroxyamide, so that a portion exposed to ultraviolet rays can be removed with an alkaline aqueous solution. A resin precursor composition can be obtained.

The polyamic acid ester in the present invention can be synthesized by various methods. The following is a general synthesis method. First, a tetracarboxylic dianhydride is esterified with an alcohol to synthesize a dicarboxylic diester. Next, the carboxyl group of the dicarboxylic acid diester is converted to an acid chloride with thionyl chloride or the like to synthesize a dicarboxylic acid chloride diester. The polycarboxylic acid ester is synthesized by reacting the dicarboxylic acid chloride diester with the diamine. Instead of acid-chlorinating the carboxyl group of the dicarboxylic acid diester with thionyl chloride or the like, a method of reacting the dicarboxylic acid diester with a condensing agent such as DCC (dicyclohexylcarbodiimide) and then reacting with a diamine to synthesize a polyamic acid ester Is also known.

The alcohol used in the synthesis of the polyamic acid ester may be photoreactive and may or may not have an ethylenically unsaturated bond. Examples of the photoreactive alcohol having no ethylenically unsaturated bond include, but are not limited to, methyl alcohol, ethyl alcohol, propyl alcohol, and butyl alcohol. On the other hand, alcohols having photoreactivity and also having an ethylenically unsaturated bond include hydroxyethyl methacrylate, hydroxyethyl acrylate, hydroxypropyl methacrylate, hydroxypropyl acrylate, hydroxymethyl methacrylate, hydroxymethyl acrylate, hydroxybutyl methacrylate, hydroxybutyl acrylate, Hydroxypentyl methacrylate, hydroxypentyl acrylate,
Examples include, but are not limited to, hydroxyisopropyl methacrylate, hydroxyisopropyl acrylate, hydroxyisobutyl methacrylate, hydroxyisobutyl acrylate, and the like.

Hereinafter, the polyimide precursor composition means polyamic acid, polyamic acid ester, or polyhydroxyamide.

The tetracarboxylic dianhydride in the present invention is:
It is represented by the general formula (1).

[0013]

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R ¹ in the formula represents a tetravalent organic group having 2 to 22 carbon atoms. In the present invention, as the tetracarboxylic dianhydride, for example, an aliphatic or alicyclic type can be used, and specific examples thereof include butanetetracarboxylic dianhydride and pentanetetracarboxylic dianhydride. Hexanetetracarboxylic dianhydride, cyclopropanetetracarboxylic dianhydride, cyclobutanetetracarboxylic dianhydride, cyclopentanetetracarboxylic dianhydride,
Examples include cyclohexanetetracarboxylic dianhydride, bicyclohexenetetracarboxylic dianhydride, and methylcyclohexenetetracarboxylic dianhydride. Also,
When an aromatic compound is used, a polyimide precursor composition that can be converted into a polyimide having good heat resistance can be obtained, and specific examples thereof include 3,3 ′, 4,4′-benzophenonetetracarboxylic acid. Acid dianhydride, pyromellitic dianhydride, 3,4,9,10-perylenetetracarboxylic dianhydride, 4,4′-sulfonyldiphthalic dianhydride, 3,3 ′, 4,4 ′ -Biphenyltetracarboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 1,4,5,8-naphthalene Examples thereof include tetracarboxylic dianhydride and 2,3,5,6-pyridinetetracarboxylic dianhydride, but are not particularly limited thereto. In the present invention, one or more of these tetracarboxylic dianhydrides are used.

The diamine used in the present invention is represented by the general formula (2).

[0016]

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Here, R ² in the formula is the above-mentioned one having 1 to 2 carbon atoms.
2 represents a divalent organic group. As a specific example,
4'-diaminodiphenyl ether, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylsulfone, 4,4'-diaminodiphenylsulfide,
m-phenylenediamine, p-phenylenediamine,
2,4-diaminotoluene, 2,5-diaminotoluene, 2,6-diaminotoluene, benzidine, 3,3 ′
-Dimethylbenzidine, 3,3'-dimethoxybenzidine, o-tolidine, 4,4 "-diaminoterphenyl,
1,5-diaminonaphthalene, 2,5-diaminopyridine, 3,3′-dimethyl-4,4′-diaminodiphenylmethane, 4,4′-bis (p-aminophenoxy) biphenyl, 2,2-bis [4 -(P-aminophenoxy) phenyl] propane, hexahydro-4,7-methanoindanylene dimethylene diamine, and the like, but are not particularly limited thereto.

In order to improve the adhesion to the inorganic substrate, siloxane diamine may be used. The siloxane diamine preferably used is represented by the general formula (3).

[0019]

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Where R in the formula^ThreeIs divalent having 1 to 10 carbon atoms
An organic group of R^Four, R^Five, R⁶, And R ⁷Has 1 to 10 carbon atoms
Which are the same but different
You may. M represents an integer of 1 to 10. Shiroki
Sun diamine is usually 1 to 20 mol% of the total diamine.
Used. Adhesiveness if the amount of siloxane diamine is too small
The improvement effect is not exhibited, and if too much, the heat resistance decreases.
As a specific example of the siloxane diamine, bis-3- (A
Minopropyl) tetramethylsiloxane and the like
You. In the present invention, one or more of these diamines are used.
Used above.

The compound having a tertiary amino group according to the present invention is represented by the general formula (4).

[0022]

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Here, R ⁸ , R ⁹ and R ¹⁰ in the formula have 1 to 1 carbon atoms.
Ten monovalent organic groups, which may be the same or different. Specific examples include triethylamine, trimethylamine, trinormalpropylamine, trinormalbutylamine, methyldiethylamine, dimethylnormalpropylamine, N, N-dibutyl-2-ethylethylhexylamine, N-methyldiallylamine,
3-dimethylaminopropanol, N-isobutyldiethanolamine, dimethyl-3-dimethoxypropylamine, N, N, N, N-tetramethyl-1,2-diaminomethane, N, N, N, N-tetramethyldiaminopropane, N, N , N, N-tetraallyl-1,4-diaminobutane, N, N, N, N-pentamethyldiethylenetriamine, N, N, N, N-dimethylbenzylamine,
Dimethylaminoacetaldehyde diethyl acetal,
Examples include, but are not limited to, compounds having no photoreactive ethylenically unsaturated bond, such as 2-dimethylaminoethyl acetate and dicyclohexylmethylamine.

The compound having a tertiary amino group is used in an amount of 0.05 to 2 molar equivalents, more preferably 0.1 to 1 molar equivalent, relative to the carboxyl group or ester group in the polyamic acid or polyamic acid ester molecule. It is desirable to mix equivalent amounts. If the mixing amount is too small, the photosensitive characteristics will be poor, and if the mixing amount is too large, the amount of decrease in the film thickness will be too large when the polyimide precursor film is heat-treated to form the polyimide film.

The compound having a photoreactive ethylenically unsaturated bond and an amino group in the present invention is represented by the general formula (5).

[0026]

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In the formula, R ¹¹ is a monovalent organic group having 1 to 10 carbon atoms having an ethylenic unsaturated bond, and R ¹² and R ¹³ are monovalent organic groups having 1 to 10 carbon atoms. May be the same or different.

Specific examples of the photoreactive compound containing an ethylenically unsaturated bond and an amino group include N, N-dimethylaminoethyl acrylate, N, N-diethylaminoethyl acrylate, and N, N-dimethylaminopropyl. Acrylate, N, N-diethylaminopropyl acrylate, N, N-dimethylaminobutyl acrylate, N, N-diethylaminobutyl acrylate and N, N-dimethylaminoethyl methacrylate, N, N
-Diethylaminoethyl methacrylate, N, N-dimethylaminopropyl methacrylate, N, N-diethylaminopropyl methacrylate, N, N-dimethylaminobutyl methacrylate, N, N-diethylaminobutyl methacrylate, N, N-dimethylaminoethyl acrylamide, N, N N-diethylaminopropyl acrylamide, N, N-dimethylaminoethyl methacrylamide, N, N-dimethylaminopropyl methacrylamide, N, N-diethylaminoethyl methacrylamide,
N, N-diethylaminopropyl methacrylamide, 2
-Vinylpyridine, 4-vinylpyridine, allylamine, 2-methylallylamine, diallylamine, and the like, but are not particularly limited thereto. However, from the viewpoint of photoreactivity, an amino compound having an acryl group or a methacryl group as an unsaturated group is desirable.

The compound containing an ethylenically unsaturated bond and an amino group is used in an amount of 0.05 to 2 times, preferably 0.1 to 1 times, the molar equivalent of the carboxyl group or ester group of the polyimide precursor composition. It is desirable to mix molar equivalents. If the mixing amount is too small, the photosensitive characteristics will be poor, and if the mixing amount is too large, the amount of decrease in the film thickness will be too large when the polyimide precursor film is heat-treated to form the polyimide film.

In the photosensitive polyimide of the present invention, a compound containing a photoreactive ethylenically unsaturated bond but containing no amino group can be used. Specific examples thereof include allyl acrylate, benzyl acrylate and benzyl acrylate. Butoxyethyl acrylate, butoxytriethylene glycol acrylate, cyclohexyl acrylate, dicyclopentanyl acrylate, dicyclopentenyl acrylate, 2-ethylhexyl acrylate, glycerol acrylate, glycidyl acrylate, heptadecafluorodecyl acrylate, 2-hydroxyethyl acrylate, isobonyl acrylate ,
2-hydroxypropyl acrylate, isodecyl acrylate, isooctyl acrylate, lauryl acrylate, 2-methoxyethyl acrylate, methoxyethylene glycol acrylate, methoxydiethylene glycol acrylate, methoxytriethylene glyco-
Acrylate, methoxydipropylene glycol acrylate, octafluoropentyl acrylate, phenoxyethyl acrylate, stearyl acrylate, trifluoroethyl acrylate, allylated cyclohexyl diacrylate, bisphenol A diacrylate,
1,4-butanediol diacrylate, 1,3-butylene glycol diacrylate, ethylene glycol diacrylate, diethylene glycol diacrylate,
Triethylene glycol diacrylate, polyethylene glycol diacrylate, dipentaerythritol hexaacrylate, dipentaerythritol monohydroxypentaacrylate, ditrimethylolpropane tetraacrylate, glycerol diacrylate, methoxylated cyclohexyl diacrylate, neopentyl glycol diacrylate, pentaerythritol Triacrylate, pentaerythritol tetraacrylate, propylene glycol diacrylate, polypropylene glycol diacrylate, triglycerol diacrylate, trimethylolpropane triacrylate, and allyl methacrylate, benzyl methacrylate, butoxyethyl methacrylate, butoxytriethylene glycol meth Acrylate, cyclohexyl methacrylate, dicyclopentanyl methacrylate, dicyclopentenyl methacrylate, 2-ethylhexyl methacrylate, glycerol methacrylate, glycidyl methacrylate, heptadecafluorodecyl methacrylate, 2-hydroxyethyl methacrylate, isobonyl methacrylate, 2-hydroxypropyl methacrylate, iso Decyl methacrylate, isooctyl methacrylate, lauryl methacrylate, 2-methoxyethyl methacrylate, methoxyethylene glycol methacrylate, methoxydiethylene glycol methacrylate, methoxytriethylene glycol methacrylate,
Methoxydipropylene glycol methacrylate, octafluoropentyl methacrylate, phenoxyethyl methacrylate, stearyl methacrylate, trifluoroethyl methacrylate, allylated cyclohexyl dimethacrylate, bisphenol A dimethacrylate, 1,
4-butanediol dimethacrylate, 1,3-butylene glycol dimethacrylate, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, dipentaerythritol hexamethacrylate, dipentaerythritol monohydroxypentamethacrylate , Ditrimethylolpropane tetramethacrylate, glycerol dimethacrylate, methoxylated cyclohexyl dimethacrylate, neopentyl glycol dimethacrylate, pentaerythritol trimethacrylate, pentaerythritol tetramethacrylate, propylene glycol dimethacrylate, polypropylene glycol dimethacrylate, triglyceride Over dimethacrylate, trimethylolpropane trimethacrylate, .gamma.-methacryloxypropyl the like trimethoxysilane include, but are not particularly limited thereto. Further, the aforementioned N-methylacrylamide, N-methylmethacrylamide, N-ethylmethacrylamide, N, N-dimethylacrylamide,
An amide compound containing an ethylenically unsaturated bond, such as N, N-diethylacrylamide, N-acryloylmorpholine, N-vinylpyrrolidone, is used as a compound containing an ethylenically unsaturated bond and containing no amino group. You can also. In the present invention, one or two of these are used.
More than one species can be used.

The compound containing an ethylenically unsaturated bond and containing no amino group is a compound of the polyimide precursor 1
It is desirable to use -100% by weight, preferably 5-50% by weight, more preferably 10-25% by weight. If the amount of the compound containing an ethylenically unsaturated bond and containing no amino group is too large, phase separation may occur between the polyimide precursor film and the polyimide precursor film during the formation of the polyimide precursor film, or the polyimide precursor film may be heat-treated. When a polyimide film is formed, problems such as an excessive decrease in film thickness occur. If the amount is too small, the photosensitive properties of the photosensitive composition will be poor.

Specific examples of the photopolymerization initiator used in the present invention include benzophenone, methyl o-benzoylbenzoate, 4,4'-bis (dimethylamino) benzophenone, and 4,4'-bis (diethylamino) benzophenone. 4,4'-dichlorobenzophenone, 4-benzoyl-4'-methyldiphenylketone, dibenzylketone, fluorenone, 2,2'-diethoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2-hydroxy- 2-methylpropiophenone, p
-T-butyldichloroacetophenone, thioxanthone, 2-methylthioxanthone, 2-chlorothioxanthone, 2-isopropylthioxanthone, diethylthioxanthone, benzyl, benzyldimethylketal, benzyl-β-methoxyethylacetal, benzoin,
Benzoin methyl ether, benzoin butyl ether, anthraquinone, 2-t-butylanthraquinone,
2-amylanthraquinone, β-chloroanthraquinone, anthrone, benzanthrone, dibenzosuberone, methyleneanthrone, 4-azidobenzalacetophenone, 2,6-bis (p-azidobenzylidene) cyclohexanone, 2,6-bis (p- Azidobenzylidene) -4-methylcyclohexanone, 1-phenyl-
1,2-butanedione-2- (o-methoxycarbonyl) oxime, 1-phenyl-propanedione-2-
(O-ethoxycarbonyl) oxime, 1-phenyl-
Propanedione-2- (o-benzoyl) oxime,
1,3-diphenyl-propanetrione-2- (o-ethoxycarbonyl) oxime, 1-phenyl-3-ethoxy-propanetrione-2- (o-benzoyl) oxime, Michler's ketone, N-phenylglycine, 3-phenyl- 5-isoxazolone, 1-hydroxycyclohexylphenyl ketone, 2-methyl- [4- (methylthio) phenyl] -2-morpholino-1-propanone, naphthalenesulfonyl chloride, quinoline sulfonyl chloride, N-phenylthioacridone,
4,4′-azobisisobutyronitrile, diphenyl disulfide, benzothiazole disulfide, triphenylphosphine, camphorquinone, carbon tetrabromide, tribromophenylsulfone, naphthoquinonediazidesulfonic acid ester, and the like, and particularly, Not limited. In the present invention, one or more of these can be used.

The amount of the photopolymerization initiator contained in the present invention is:
0.1 to 30% by weight of the polyimide precursor is preferred,
0.1-15% by weight is more preferred. If the amount of the photopolymerization initiator is too small, the photosensitivity of the composition becomes poor, and if the amount of the photopolymerization initiator is too large, the film thickness decreases when the polyimide precursor film is heat-treated to form a polyimide film. The amount is too large.

A sensitizer capable of improving photosensitivity may be added to the polyimide precursor composition of the present invention. Specific examples of the sensitizer include 2,5-bis (4′-diethylaminobenzal) cyclopentanone and 2,6-bis (4 ′
-Dimethylaminobenzal) cyclohexanone, 2,6
-Bis (4'-dimethylaminobenzal) -4-methylcyclohexanone, 2,6-bis (4'-diethylaminobenzal) -4-methylcyclohexanone, Michler's ketone, 4,4'-bis (diethylamino) -benzophenone, 4,4'-bis (dimethylamino) chalcone,
4,4′-bis (diethylamino) chalcone, p-dimethylaminocinnamylidene indanone, p-dimethylaminobenzylidene indanone, 2- (p-dimethylaminophenylvinylene) benzothiazole, 2- (p-dimethylaminophenyl Vinylene) -isonaphthothiazole, 1,3-bis (4′-dimethylaminobenzal) acetone, 1,3-bis (4′-diethylaminobenzal) acetone, 3,3′-carbonyl-bis (7-diethylamino) Coumarin), N-phenyl-N'-ethylethanolamine, N-phenyldiethanolamine, N
-Tolyldiethanolamine, N-phenylethanolamine, isoamyl dimethylaminobenzoate, isoamyl diethylaminobenzoate, 3-phenyl-5-isoxazolone, 1-phenyl-5-benzoylthiotetrazole, 1-phenyl-5-ethoxycarbonylthiotetrazole And the like, but not particularly limited thereto. In the present invention, one or more of these sensitizers can be used. Some of the sensitizers also act as photopolymerization initiators.

When a sensitizer is added in the present invention, the addition amount is preferably 0.1 to 30% by weight of the polyimide precursor, more preferably 0.5 to 15% by weight. If the addition amount is too large, the amount of decrease in the film thickness when the polyimide precursor film is heat-treated to form a polyimide film becomes too large.
On the other hand, if the amount is too small, the effect of improving the photosensitivity is not exhibited.

In order to improve the thermal stability during storage of the photosensitive polyimide precursor composition of the present invention, a thermal polymerization inhibitor may be added. Specific examples of the thermal polymerization inhibitor include hydroquinone, N-nitrosodiphenylamine, phenothiazine, pt-butylcatechol, N-
Phenylnaphthylamine, 2,6-di-t-butyl-p
-Methylphenol, chloranil, pyrogallol and the like, but are not particularly limited thereto.

When a thermal polymerization inhibitor is added, the amount thereof is preferably 0.1 to 20% by weight of the polyimide precursor, more preferably 0.5 to 10% by weight. If the addition amount is too large, in the polyimide pattern processing process, the film surface becomes rough or peeled off, the rate of reduction in film thickness after development becomes large, and the exposure effect decreases. On the other hand, if the amount is too small, the effect of improving the thermal stability during storage is not exhibited.

The colloidal silica in the present invention is a colloidal solution of high molecular weight silicic anhydride. An example of this is commercially available as a silica sol. The dispersion medium is usually water, but a dispersion in an organic solvent (organo silica sol) is also commercially available. The silica sol dispersed in the organic solvent is adjusted by replacing water, which is a dispersion medium of the aqueous silica sol, with an organic solvent. The replacement of the dispersion medium can be carried out by adding an organic solvent to the aqueous silica sol and distilling off water by means such as distillation. From the viewpoint of compatibility with the polyimide precursor, an organosilica sol dispersed in an organic solvent is desirable. In particular, an organosilica sol dispersed in an aprotic polar solvent such as dimethylformamide, dimethylacetamide, or N-methyl-2-pyrrolidone which is a solvent for polyamic acid is preferable.

Other colloidal silicas usable in the present invention include colloidal silicas synthesized from alkyl silicates.

Alkyl silicate is represented by the general formula Si (O
R ¹⁴ ) 4 (wherein R ¹⁴ is a hydrocarbon having 1 to 15 carbon atoms). Colloidal silica synthesized from the alkyl silicate used in the present invention is produced by hydrolytic condensation of the alkyl silicate,
For example, it is obtained by adding tetraethyl silicate to a mixed solution of methanol and aqueous ammonia, performing hydrolytic condensation, and then adding an appropriate dispersion medium to distill off methanol and ammonia. As the dispersion medium, it is preferable to use an organic solvent from the viewpoint of compatibility with the polyimide precursor. In particular, dimethylacetamide, dimethylformamide, N
Aprotic polar solvents such as -methyl-2-pyrrolidone are preferred. In this method, the raw material has a low sodium ion content, so that it can be suitably used.

The amount of colloidal silica to be added is preferably 1 to 50% by weight, more preferably 5 to 30% by weight, based on the solid content of the polyimide precursor. However, it is necessary that the concentration of sodium ions in the heat-treated film be within a range of 10 ppm or less.

The amount of sodium ion in the colloidal silica is determined by weighing the solution in a platinum dish, evaporating the solvent with an infrared lamp, and incineration with a burner and an electric muffle furnace. After incineration, it is dissolved with hydrofluoric acid and sulfuric acid, evaporated to dryness, dissolved in dilute hydrochloric acid, and this solution is quantified as a measurement solution. The quantification is performed by an atomic absorption method.

The hydrofluoric / nitric acid used in the present invention is a mixture of hydrofluoric acid and nitric acid, containing 100% of hydrofluoric acid, hydrofluoric acid (47% by weight) and nitric acid (specific gravity of 1.3).
The ratio of 8) means a solution having a weight ratio of 1: 0 to 1:10.

The organic solvent used in the above method is preferably one in which a composition other than colloidal silica can be dissolved, and N-methyl-2-pyrrolidone, N, N-dimethylacetamide, N, N-dimethyl Formamide,
Polar solvents such as dimethylsulfoxide, tetramethylurea, hexamethylphosphoric triamide, and γ-butyrolactone are usually used. In addition, ketones, esters, ethers, halogenated hydrocarbons, hydrocarbons, etc. which are common organic solvents other than these polar solvents, such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, methyl acetate, Ethyl acetate,
Butyl acetate, diethyl oxalate, diethyl malonate, diethyl ether, ethylene glycol dimethyl ether, tetrahydrofuran, dichloromethane, 1,2-dichloroethane, 1,4-dichlorobutane, trichloroethane, chlorobenzene, o-dichlorobenzene, hexane, Heptane, octane, benzene, toluene, xylene and the like can also be used. Furthermore, amide compounds containing an ethylenically unsaturated bond, for example, N-methylacrylamide, N-methylmethacrylamide, N-ethylmethacrylamide, N, N-dimethylacrylamide,
N-diethylacrylamide, N-acryloylmorpholine, N-vinylpyrrolidone and the like can also be used.

As a method of applying the varnish on the substrate, a method of applying the substrate to the substrate by a spin coater, a bar coater, a blade coater, a screen printing method, or the like, a method of dipping the substrate in the varnish, and a method of spraying the varnish on the substrate. Various methods can be used.

As the substrate in the present invention, semiconductors such as silicon and gallium-arsenic, alumina ceramics,
Inorganic insulators such as glass ceramics and sapphire, and metals such as aluminum and copper can be selected.

The varnish having photosensitivity and the varnish having no photosensitivity are each subjected to pattern processing by the following method.

For a varnish having no photosensitivity, a polyimide precursor film is formed by coating the varnish on a substrate, and then drying it by air drying, heating drying, or vacuum drying. Thereafter, pattern processing using a resist can be performed. A hydrazine process using a negative resist and a process of etching a resist and a polyimide at a time using a positive resist are known. To explain an example of the latter, after forming a polyimide precursor film as described above, a positive resist is applied and dried by pre-baking.

The film obtained by pre-baking a positive resist on the polyimide precursor thus obtained is exposed using a usual photomask. The actinic rays used at this time include, for example, ultraviolet rays, electron beams, X-rays, etc. Among them, ultraviolet rays are preferable, and as the light source, for example, a low-pressure mercury lamp, a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, a halogen Lamps, germicidal lamps and the like. Among these light sources, an ultra-high pressure mercury lamp is preferred. Exposure is preferably performed in a nitrogen atmosphere or in a vacuum.

After the exposure, if necessary, a heat treatment is performed, and then development is performed using a developer to remove the exposed portions. In this case, an immersion method or a spray method can be used. As the developer, an aqueous alkali solution is usually used, and specifically, sodium hydroxide, tetramethylammonium hydroxide, tetraethylammonium hydroxide, choline and the like are used. Immediately after the development, rinsing with an organic solvent such as ethyl alcohol, isopropyl alcohol, isobutyl alcohol, hexane or pentane or water is desirable. After pattern processing, the positive resist is peeled off. Specific examples of the stripping solution include butyl acetate, methyl isobutyl ketone, ethyl cellosolve acetate, propylene glycol monomethyl ether acetate, and the like.

For the photosensitive varnish, after applying the varnish on the substrate, a photosensitive polyimide precursor film is formed by air drying, heat drying, vacuum drying, or the like. The film thus obtained is exposed using a normal photomask. As the actinic rays used at this time, the same rays as those used in the exposure of the resist are used.

After the exposure, if necessary, a heat treatment is carried out, and then development is carried out using a developer to remove unexposed portions or exposed portions. In this case, an immersion method or a spray method can be used.

As the developing solution, those similar to the organic solvents which can dissolve the polyimide precursor are usually used. In addition, water can be added to such an organic solvent in order to improve the developability. When water is added, the amount is usually 1 to 100% by weight, preferably 5 to 50% by weight, based on the organic solvent. If the amount is too large,
There is a possibility that phase separation may occur with an organic solvent, and if the addition amount is too small, the effect of improving developability is not exhibited. In the case of an alkaline aqueous solution, sodium hydroxide, tetramethylammonium hydroxide, tetraethylammonium hydroxide, choline and the like are used. Immediately after development, ethyl alcohol,
It is desirable to perform rinsing with water or an organic solvent such as isopropyl alcohol, isobutyl alcohol, hexane, or pentane.

The pattern of the polyimide precursor obtained after the development or after the removal of the resist is converted into a polyimide pattern by heating. The heat treatment is usually performed in a nitrogen atmosphere or in a vacuum at 150 to 4 times.
It is carried out continuously or stepwise at a temperature of 50 ° C. for 0.5 to 5 hours.

The etching with hydrofluoric acid in the present invention includes, for example, the following cases. That is, a semiconductor element having a high withstand voltage and a large current, such as a power diode
In a device such as a thyristor, after a polyimide cured film is formed, the back surface or a part of the front surface of the semiconductor substrate is further etched by a post-processing with a mixed solution of hydrofluoric acid and nitric acid.

By the etching treatment, sodium ions existing on the surface and inside of the heat-treated film of polyimide, particularly colloidal silica, may be dissolved to deteriorate the characteristics of the device. The effect of sodium ions on the device varies depending on the type of device and the etching time, but when the concentration of sodium ions in the heat-treated film becomes 10 ppm or more, device failure starts to be recognized. , 10p
pm or less, more preferably 3 ppm
The following is preferred.

The amount of sodium in the heat-treated film was determined by weighing it on a platinum dish and evaporating the solvent with an infrared lamp.
Ash in a burner and an electric muffle furnace. After incineration, it is dissolved with hydrofluoric acid and sulfuric acid, evaporated to dryness, then dissolved in dilute hydrochloric acid, evaporated to dryness, dissolved in dilute hydrochloric acid, and the solution is quantified as a measurement solution. The quantification is performed by an atomic absorption method.

[0058]

EXAMPLES The present invention will now be described specifically with reference to examples, but the present invention is not limited to these examples.

Example 1 100 equipped with a thermometer, a dry nitrogen inlet and a stirrer
In a 0 ml four-necked flask, 56.45 g of 4,4′-diaminodiphenyl ether and 4.47 g of bis (3-aminopropyl) tetramethyldisiloxane were dissolved in 680 g of N-methyl-2-pyrrolidone, and room temperature (about 20
While stirring at 4 ° C.), 48.3 g of benzophenonetetracarboxylic dianhydride and 32.7 g of pyromellitic dianhydride.
g of powder and stirred at room temperature for 1 hour.
The stirring was continued for 2 hours to obtain a polymer solution (A) of 50 poise at 25 ° C. A colloidal silica solution (a) in which colloidal silica having 45 g of N, N'-dimethylaminoisobutyl and a sodium ion concentration of 10 ppm was dispersed in N-methyl-2-pyrrolidone was added to this polymer solution (A) (concentration 3
After stirring and mixing 40 g of a (0 wt% solution), the mixture was filtered with a filter to obtain a polyimide precursor composition solution.

This solution was spin-coated on a silicon substrate on which electrodes and elements were formed, and dried by heating at 80 ° C. for 30 minutes to form a film having a thickness of 8 μm. A positive resist “OFPR-800” (100 cps product,
Tokyo Oka Co., Ltd.) and apply 105
The resist film was dried by pre-baking at 2 ° C. for 2 minutes to form a resist film having a thickness of about 3 μm. A g-line stepper (NSR-1505 manufactured by Nikon Corporation) is applied to this film surface via a pattern mask.
G6E) at an exposure dose of 250 mJ / cm ² . Development is performed by NMD-3 manufactured by Tokyo Ohka Co., Ltd.
It was immersed at a temperature of 22 ° C. for 160 seconds to dissolve the exposed part.
Rinse with water and air dry. The positive resist was peeled off by dipping it in normal butyl acetate for 2 minutes and air-dried. This was heat-treated in a nitrogen atmosphere in steps of 200 ° C. for 30 minutes, 300 ° C. for 30 minutes, and 400 ° C. for 30 minutes to obtain a thickness of 5 ° C.
A μm polyimide pattern was obtained. Next, the resultant was immersed in an etching solution of an aqueous solution of nitric acid 1 having a specific gravity of 1.38 (weight ratio) with respect to an aqueous solution of hydrofluoric acid 1 having a concentration of 47% at a room temperature of 25 ° C. for 30 seconds. The polyimide does not peel off from the substrate,
The polyimide covering the electrode showed sufficient properties as an insulating film and a protective film. When the characteristics of the device were examined, it was confirmed that the device operated well. Also, when the sodium ion concentration of the polyimide cured film was measured,
0.7 ppm.

Comparative Example 1 In Example 1, the colloidal silica was replaced with “OSCAL”.
-NP45 "(manufactured by Catalysis Chemical Industry Co., Ltd.) was replaced with colloidal silica, and the same operation was performed. As a result, poor device characteristics were observed. The sodium concentration of the polyimide cured film was 338 ppm. The sodium ion concentration in the colloidal silica of "OSCAL-NP45" was determined to be 4333 ppm by the method described in the text.

Comparative Example 2 The same operation as in Example 1 was carried out using a varnish containing no colloidal silica, and peeling of the polyimide film was observed by the treatment with the etching solution.

Example 2 100 equipped with a thermometer, a dry air inlet and a stirrer
In a 0 ml four-necked flask, 147.11 g of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride (0.17 g) was added.
5 mol), 2-hydroxyethyl methacrylate
07 g (0.5 mol) and 300 g of N-methyl-2-pyrrolidone were added, and the mixture was stirred at 70 ° C. for 4 hours under a flow of dry air. Thereafter, the mixture was cooled to room temperature, and 75.09 g (0.375 mol) of 4,4′-diaminodiphenyl ether was added.
-10.81 g (0.1 mol) of phenylenediamine, 6.21 g (0.025 mol) of bis-3- (aminopropyl) tetramethylsiloxane and N-methyl-2
-193.11 g of pyrrolidone are added and under dry air inflow,
The mixture was stirred at 60 ° C. for 3 hours to obtain a viscous polyimide precursor solution (B). 160 g of N, N'-dimethylaminoisobutyl and 0.3 g of a 1% N-methyl-2-pyrrolidone solution of a pluronic surfactant ("Pronon" 204, manufactured by NOF CORPORATION) were added to the polymer solution (B). After stirring and mixing 80 g of the colloidal silica solution (a) of Example 1, the mixture was filtered with a filter to obtain a polyimide precursor composition solution.

This solution was spin-coated on a silicon substrate on which electrodes and elements had been formed, and prebaked on a hot plate at 80 ° C. for 2 minutes, and then prebaked on a hot plate at 130 ° C. for 2 minutes. A film was prepared.

Next, a polyimide pattern having a thickness of 5 μm was obtained in the same manner as in Example 1. When the polyimide was further etched, the polyimide was not peeled off from the substrate. The film exhibited sufficient properties. When the characteristics of the device were examined, it was confirmed that the device operated well. When the sodium ion concentration of the polyimide cured film was measured, it was 1 ppm.

Comparative Example 3 In Example 2, the colloidal silica was changed to “OSCAL-
When the same operation was performed with the change to NP45 ″ colloidal silica, poor device characteristics were observed. The sodium concentration of the polyimide cured film was measured to be 40%.
It was 5 ppm.

Comparative Example 4 The same operation as in Example 2 was carried out using a varnish containing no colloidal silica, and peeling of the polyimide film was observed by the treatment with the etching solution.

Example 3 1 g of Michler's ketone, 1 g of 4-azidobenzalacetophenone and 3-phenyl-5-isoxazolone 5 were added to the polymer solution (A) obtained in Example 1 at room temperature under light shielding.
g, 3,3′-carbonyl-bis (7-diethylaminocoumarin) 0.25 g, ethylene glycol dimethacrylate 5 g, N, N′-dimethylaminoethyl methacrylate 45 g, colloidal silica solution of Example 1 (a)
After stirring and mixing 40 g, the mixture was filtered through a filter to obtain a photosensitive polyimide precursor composition solution.

This solution was spin-coated on a silicon substrate on which electrodes and elements had been formed, and dried by heating at 80 ° C. for 30 minutes to form a film having a thickness of 15 μm. This film surface was subjected to pattern masking, and exposure was performed for 5 minutes in a nitrogen atmosphere using an ultra-high pressure mercury lamp having an output of 7 mW / cm ² ,
N-methyl-2-pyrrolidone, xylene, water 7: 2:
1 (weight ratio) and developed until the unexposed portion was dissolved and removed. At this time, the time required for development was 120 seconds. After development, rinsing with isobutyl alcohol gave a 13.5 μm-thick polyimide precursor pattern. The film thickness retention at this time was as good as 90%. This was placed in a nitrogen atmosphere at 200 ° C. for 30 minutes
Heat treatment was performed in steps of 0 ° C. for 30 minutes and 400 ° C. for 30 minutes to obtain a polyimide pattern having a thickness of 8 μm.

When etching was performed in the same manner as in Example 1,
The polyimide did not peel off from the substrate, and the polyimide covering the element portion and the electrode showed sufficient properties as an insulating film and a protective film. When the characteristics of the device were examined, it was confirmed that the device operated well. When the sodium ion concentration of the polyimide cured film was measured, it was 0.7 ppm.

Comparative Example 5 In Example 3, the colloidal silica was changed to “OSCAL-
When the same operation was performed with the change to NP45 ″ colloidal silica, poor device characteristics were observed. The sodium concentration of the polyimide cured film was measured to be 33.
It was 8 ppm.

Comparative Example 6 The same operation as in Example 3 was carried out using a varnish containing no colloidal silica, and peeling of the polyimide film was observed by the treatment with the etching solution.

Example 4 To a polymer solution (B) obtained in Example 2 was added 2.39 g of 4-azidobenzalacetophenone at room temperature under light shielding.
14.35 g of N-phenylglycine, 11.96 g of ethylene glycol dimethacrylate, 157.21 g (1 mol) of N, N-dimethylaminoethyl methacrylate,
Pluronic type surfactant (Nippon Yushi Co., Ltd. "Pronon" 204) 1% N-methyl-2-pyrrolidone solution 0.
3 g, and the colloidal silica solution (a) 8 of Example 1 was added.
After stirring and mixing 0 g, the mixture was filtered through a filter to obtain a photosensitive polyimide precursor composition solution.

This solution was spin-coated on a silicon substrate on which electrodes and elements had been formed, and prebaked on a hot plate at 80 ° C. for 3 minutes, and then on a hot plate at 100 ° C. for 3 minutes. A film was prepared. This film surface was subjected to a pattern mask, and a 1 mW / cm ² output ultra-high pressure mercury lamp was used in a nitrogen atmosphere.
Exposure for 5 seconds, 60 ° C on hot plate just before development
After processing for 2 minutes, the film was developed with a developer DV-605 (manufactured by Toray Industries, Ltd.) until unexposed portions were dissolved and removed. At this time, the time required for development was 60 seconds. After the development, rinsing was performed with isopropyl alcohol, and the solution was spun at high speed to shake off the solution. As a result, a polyimide precursor pattern having a thickness of 14 μm was obtained. The film thickness retention at this time was 9
It was as good as 0% or more. In a nitrogen atmosphere,
Heat treatment was performed at steps of 30 ° C. for 30 minutes, 300 ° C. for 30 minutes, and 400 ° C. for 30 minutes to obtain a polyimide pattern having a thickness of 8 μm.

When etching was performed in the same manner as in Example 1,
The polyimide did not peel off from the substrate, and the polyimide covering the element portion and the electrode showed sufficient properties as an insulating film and a protective film. When the characteristics of the device were examined, it was confirmed that the device operated well. When the sodium ion concentration of the polyimide cured film was measured, it was 1 ppm.

Comparative Example 7 In Example 4, the colloidal silica was changed to “OSCAL-
When the same operation was performed after changing to NP45 ″, poor device characteristics were observed. The sodium concentration of the polyimide cured film was 405 ppm.

Comparative Example 8 The same operation as in Example 4 was performed using a varnish containing no colloidal silica, and peeling of the polyimide film was observed by the treatment with the etching solution.

Example 5 65.5 g of pyromellitic dianhydride and 3,3 ′, 4
4'-benzophenonetetracarboxylic acid and anhydride 22
5.5 g of 2-hydroxyethyl methacrylate 26
Esterification was performed with 0.28 g to obtain a polyamic acid ester of 4,4′-diaminodiphenyl ether 200.23 using dicyclohexylcarbodiimide as a condensing agent. After dicyclohexylurea was filtered off, the precipitate was reprecipitated with methanol and the solid substance was dried in vacuum. At room temperature under light protection, 4.9 g of 4-azidobenzalacetophenone, N-
14.35 g of phenylglycine, 11.96 g of ethylene glycol dimethacrylate, and 170 g of the colloidal silica solution (a) of Example 1 were mixed with stirring, followed by filtration with a filter to obtain a photosensitive polyimide precursor composition solution.

Next, a film having a thickness of 15 μm after prebaking was produced in the same manner as in Example 4. This film surface was subjected to pattern masking, exposure was performed for 20 seconds using an ultrahigh pressure mercury lamp with an output of 7 mW / cm ² in a nitrogen atmosphere, developed with cyclopentanone, and developed until the unexposed portion was dissolved and removed. After the development, rinsing was performed with isopropyl alcohol, and the solution was spun at high speed to shake off the solution. As a result, a polyimide precursor pattern having a thickness of 14 μm was obtained. The film thickness retention at this time was as good as 90% or more. In a nitrogen atmosphere,
Heat treatment was performed in steps of 0 ° C. for 30 minutes, 300 ° C. for 30 minutes, and 400 ° C. for 30 minutes to obtain an 8 μm thick polyimide pattern.

When etching was performed in the same manner as in Example 1,
The polyimide did not peel off from the substrate, and the polyimide covering the element portion and the electrode showed sufficient properties as an insulating film and a protective film. When the characteristics of the device were examined, it was confirmed that the device operated well. When the sodium ion concentration of the polyimide cured film was measured, it was 1 ppm.

Comparative Example 9 In Example 5, the colloidal silica was changed to “OSCAL-
When the same operation was performed by changing to NP45 ″, poor device characteristics were observed. The sodium concentration of the cured polyimide film was 408 ppm.

Comparative Example 10 The same operation as in Example 5 was carried out using a varnish containing no colloidal silica, and peeling of the polyimide film was observed by the treatment with the etching solution.

Example 6 100 equipped with a thermometer, a dry nitrogen inlet and a stirrer
In a 0 ml four-necked flask, 36.6 g of bis (3-amino-4-hydroxyphenyl) hexafluoropropane was added.
Is dissolved in 240 g of N, N-dimethylacetamide,
The mixture was cooled to -10 ° C, and 139.2 g of propylene oxide was added. To this solution is added isophthalic acid dichloride 10.2
g, 4,4′-diphenyl ether dicarboxylic acid chloride (14.8 g) dissolved in acetone (50 g).
The solution was dropped over a period of minutes so that the internal temperature did not exceed 10 ° C. Thereafter, the mixture was stirred at -10 ° C for 2 hours, and further stirred at room temperature for 2 hours. After completion of the reaction, this solution was poured into 5 l of water, and the resulting polymer precipitate was collected by filtration. The precipitate was further washed with 3 l of methanol and further with 2 l of water.
This precipitate is collected and dried in a vacuum dryer at 80 ° C. for 2 days,
A polyhydroxyamide powder was obtained.

20 g of this polyhydroxyamide powder,
3 g of dicyclohexylmethylamine as a tertiary amino compound and 4 g of 4NT300 (manufactured by Toyo Gosei) as a naphthoquinonediazidesulfonic acid ester are N-methyl-2-
It was dissolved in 40 g of pyrrolidone to obtain a photosensitive polymer solution. Here, a colloidal silica solution (a) (concentration: 30 wt% solution) in which colloidal silica having a sodium ion concentration of 10 ppm is dispersed in N-methyl-2-pyrrolidone
g was stirred and mixed, and then filtered through a filter to obtain a polyimide precursor composition solution.

This solution was spin-coated on a silicon substrate on which electrodes and elements had been formed, and dried by heating on a hot plate at 120 ° C. for 4 minutes to form a 7 μm thick film. The film surface was exposed through a pattern mask using a g-line stepper (NSR-1505G6E manufactured by Nikon Corporation) at an exposure amount of 600 mJ / cm ² . The development was performed using NMD-3 manufactured by Tokyo Ohka Co., Ltd.
It was immersed for 120 seconds to dissolve the exposed part. Rinse with water and air dry. This is placed in a nitrogen atmosphere at 200 ° C. for 30 minutes.
3. heat treatment at 320 ° C. for 60 minutes;
A 5 μm pattern of polybenzoxazole was obtained. Next, the specific gravity of the aqueous hydrofluoric acid solution 1 having a concentration of 47% was 1.
The wafer was immersed in an etching solution of 38 aqueous nitric acid solution 1 (weight ratio) at room temperature 25 ° C. for 30 seconds. The polybenzoxazole did not peel off from the substrate, and the polyimide covering the element portion and the electrode showed sufficient properties as an insulating film and a protective film. When the characteristics of the device were examined, it was confirmed that the device operated well. The sodium ion concentration of the cured polybenzoxazole film was 0.7 ppm.

Comparative Example 11 In Example 6, the colloidal silica was replaced with “OSCAL”.
-NP45 "(manufactured by Catalysis Chemical Industry Co., Ltd.) was replaced with colloidal silica, and the same operation was performed. As a result, poor device characteristics were observed. The sodium concentration of the polyimide cured film was 338 ppm. The sodium ion concentration in the colloidal silica of "OSCAL-NP45" was determined to be 4333 ppm by the method described in the text.

Comparative Example 12 The same operation as in Example 6 was carried out using a varnish containing no colloidal silica, and peeling of the polybenzoxazole film was observed by the treatment with the etching solution.

[0088]

According to the present invention, since the semiconductor device is constructed as described above, according to the semiconductor element, a polyimide film having no exfoliation of the polyimide film from the substrate after the fluorinated nitric acid treatment and excellent device characteristics can be obtained. A method for manufacturing a semiconductor device having the same can be provided.

Claims (5)

[Claims] A film obtained by heat-treating a polyimide precursor composition mainly comprising (1) a polyamic acid, (2) a compound containing a tertiary amino group, and (3) colloidal silica, is provided on a substrate surface. In a semiconductor element using the heat-treated film as an insulating film or a protective film, the exposed portion is etched with hydrofluoric nitric acid so that the heat-treated film before etching has a sodium ion content of 1%.
A method for manufacturing a semiconductor device, wherein the content is 0 ppm or less. 2. A polyimide precursor composition mainly comprising (1) a polyamic acid, (2) a compound having an ethylenically unsaturated bond having photoreactivity and an amino group, and (3) colloidal silica on a substrate. A processed film is formed so that the substrate surface is selectively exposed, and the exposed portion is etched with hydrofluoric nitric acid. A method for producing a semiconductor device, characterized in that the sodium ion content of the semiconductor element is 10 ppm or less. 3. A method comprising the steps of: (1) forming a polyamic acid ester on a substrate;
(2) A film obtained by heat-treating a polyimide precursor composition mainly composed of colloidal silica is formed so that the substrate surface is selectively exposed, and the exposed portion is etched with hydrofluoric nitric acid. Alternatively, in a semiconductor element used as a protective film, the heat treatment film before etching has a sodium ion content of 10 ppm or less. 4. A method comprising: (1) a polyamic acid ester having an ethylenically unsaturated bond having photoreactivity;
Photopolymerization initiator, (3) a film obtained by heat-treating a photosensitive polyimide precursor composition mainly composed of colloidal silica,
The substrate is formed so that the substrate surface is selectively exposed, the exposed portion is etched with a mixed solution of hydrofluoric acid and nitric acid. A method for manufacturing a semiconductor device, wherein the heat treatment film has a sodium ion content of 10 ppm or less. 5. The method for manufacturing a semiconductor device according to claim 1, wherein the heat treatment film before etching has a sodium ion content of 3 ppm or less.