JP4693685B2 - Photosensitive polyamic acid ester composition - Google Patents

Description

  The present invention relates to a photosensitive material useful for the production of electrical / electronic materials such as semiconductor devices and multilayer wiring boards. More specifically, the present invention relates to a polyamic acid ester composition that has a wide film thickness region capable of i-line exposure and can provide a high resolution polyimide pattern.

Polyimide resin is attracting attention as a material related to microelectronics because of its high thermal and chemical stability, low dielectric constant, and excellent planarization ability, and is used as a semiconductor surface protective film or interlayer insulating film, or Widely used as a material for multi-chip modules.
In the case of manufacturing a semiconductor device using a polyimide resin, a polyimide resin film is usually formed on a substrate and a desired pattern is formed using a lithography technique. Specifically, an indirect pattern forming method is used in which a photoresist pattern is formed on a polyimide resin film using a photoresist and a photomask, and then polyimide resin is patterned by etching. . However, in this method, first, a photoresist pattern to be a mask is formed on the polyimide resin film, then the polyimide resin is etched, and finally the unnecessary photoresist pattern is peeled off. Therefore, the process is complicated, and the resolution is low because of indirect pattern formation. Moreover, since it is necessary to use a toxic substance such as hydrazine as a solvent for etching, there is also a safety problem.

  In order to overcome the above problems, a method of introducing a photopolymerizable photosensitive group into a polyimide precursor and directly forming a pattern on the polyimide precursor film has been put into practical use. For example, a film made of a polyimide precursor formed by bonding a compound having a double bond to a polyamic acid derivative via an ester bond, an amide bond, or an ionic bond, and a photosensitive polyimide precursor composition containing a photoinitiator or the like. Forming a pattern using means for insolubilizing the polyimide precursor of the exposed portion of the coating film by exposing it through a photomask having a pattern, and subjecting it to a development treatment. A method of converting a polyimide precursor into a polyimide having thermal stability by removing the photosensitive group component by heating has been proposed (see Non-Patent Document 1). This technology is generally called photosensitive polyimide technology. This technique overcomes the problems associated with processes using the conventional non-photosensitive polyimide precursor described above. Therefore, the polyimide pattern is often formed by the above-described photosensitive polyimide technology.

In recent years, there has been a demand for improvement in resolution when forming a pattern of a polyimide film used in a semiconductor device or the like. In the process using the non-photosensitive polyimide before the development of the above-mentioned photosensitive polyimide technology, high resolution could not be obtained. Therefore, the semiconductor device and the manufacturing process were designed on the assumption that the semiconductor device was manufactured. The integration rate and accuracy were limited. On the other hand, when the photosensitive polyimide technology is used, a high resolution can be obtained at the time of pattern formation, so that a semiconductor device with a high integration rate and high accuracy can be manufactured. This will be described below.
For example, when manufacturing a memory element or the like, in order to increase the yield of a product, an operation is performed in which a spare circuit is made in advance and unnecessary circuits are cut after the product is inspected. In the process using conventional non-photosensitive polyimide, unnecessary circuit cutting was performed before the formation of the polyimide pattern, whereas in the process using photosensitive polyimide, the resolution at the time of polyimide pattern formation is high, A hole for cutting an unnecessary circuit in the pattern is provided, and the preliminary circuit can be cut after the polyimide pattern is formed. Therefore, it becomes possible to cut the spare circuit at a stage closer to the completion time of the final product, and a higher product yield is achieved.

  When a hole for cutting unnecessary circuits is provided in the polyimide pattern, it is desired to make the hole smaller in order to achieve high integration of the semiconductor device. There is a need for photosensitive polyimide precursors that can be patterned with resolution. In addition, when a photosensitive polyimide precursor that enables high-resolution pattern formation is used in the semiconductor device manufacturing process, a wide process margin necessary for high integration and high accuracy of the semiconductor device can be achieved. Here, the “wide process margin” means that usable conditions for exposure and development (for example, conditions such as time and temperature) for pattern formation in the process are wide. Therefore, the higher the resolution when forming the polyimide pattern, the better. The above also applies when the polyimide pattern is used for other semiconductor devices (multichip module or the like). For this reason, there is an increasing demand for a photosensitive polyimide precursor composition having a high resolution that enables formation of a highly accurate pattern.

By the way, a semiconductor device (hereinafter also referred to as “element”) is mounted on a printed circuit board by various methods in accordance with purposes. A common element is a wire bonding method in which a thin wire is connected from an external terminal (pad) of the element to a lead frame. However, as the speed of the element has increased and the operating frequency has reached GHz, in today's packaging, The difference in the wiring length between the terminals has led to the influence of the device operation. For this reason, when mounting elements for high-end applications, it is necessary to accurately control the length of the mounting wiring, and wire bonding makes it impossible to meet the requirements.
Accordingly, flip chip mounting has been proposed in which a rewiring layer is formed on the surface of a semiconductor chip, bumps (electrodes) are formed thereon, the chip is flipped over, and mounted directly on a printed circuit board. Flip chip mounting is used for high-end devices that handle high-speed signals because the wiring distance can be accurately controlled, and because of the small mounting size, the demand is rapidly expanding. Therefore, in addition to the excellent pattern formability of the photosensitive polyimide precursor as described above, the pattern formability with a thick film that can cover multiple wiring layers is increasingly regarded as important for rewiring layer materials. It became so. Further, there is an increasing demand for using i-line as an exposure source when forming a pattern.

However, in the conventionally known photosensitive polyimide precursor obtained by condensing an aromatic tetracarboxylic acid and an aromatic diamine, since the absorption of i-line is large, even if a pattern can be formed in a thin film, In most cases, light did not pass to the bottom of the pattern and the desired polyimide pattern could not be obtained. As a technique for solving this problem, a technique has been proposed in which a polyamic acid ester using a specific tetracarboxylic dianhydride and a specific diamine is used to improve the transparency of a polymer to i-line (Patent Literature). 1). In addition to a polyamic acid ester using a specific tetracarboxylic dianhydride and a specific diamine, it has been proposed to use a specific photoinitiator (see Patent Document 2).
However, a photosensitive polyimide precursor composition having a higher i-line exposure film thickness than the compositions disclosed in these techniques is desired. That is, even if it is a thick coating film having a thickness of 40 to 50 μm after coating and drying of the photosensitive polyimide precursor composition, it is possible to form a pattern by i-line, and a thick film that becomes a polyimide film having a thickness of 20 to 30 μm after curing. There is a need for a photosensitive polyimide precursor composition having both i-ray curability and high resolution capable of forming a pattern having an aspect ratio (thickness / resolution after coating and drying) of 1 or more.

Yamaoka, Otomo, "Polyfile", 1990, 27, No. 2, pp. 14-18 Japanese Patent No. 2693168 Japanese Patent No. 3424085

  The present invention relates to a photosensitive polyamic acid ester composition having a wide film thickness region capable of i-line exposure and capable of giving a high resolution polyimide pattern, a method for forming a polyimide pattern using the photosensitive composition, and the polyimide pattern It is an object to provide a semiconductor device having the following.

  The present inventors are able to form a pattern with i-line even with a thick coating of 40 to 50 μm after coating and drying, and can be a polyimide film having a thickness of 20 to 30 μm after curing. And a high-resolution photosensitive polyimide precursor composition capable of forming a pattern having an aspect ratio (thickness / resolution after coating / drying) of 1 or more. As a result, the polyamic acid ester composed of a specific repeating unit, a photoinitiator, and a photosensitive polyamic acid ester composition composed of a solvent give a polyimide pattern with a wide film thickness area capable of i-line exposure and a high resolution. Found out to get. The present invention has been made based on this finding.

（式中、Ｘは２個のベンゼン環をオキシ基で結合した４価の芳香族基であり、Ｒ及びＲ’はそれぞれ独立してオレフィン性二重結合を有する１価の基であり、Ｒ" は炭素数１〜４４の直鎖あるいは分岐のアルキル基あるいはアルコキシ基である。）
一般式（１）におけるＲ" 基は、メチル基であることが好ましい。 That is, one aspect of the present invention is (A) 100 parts by mass of a polyamic acid ester composed of a repeating unit represented by the following general formula (1), (B) 1 to 15 parts by mass of a photoinitiator, and (C) a solvent. It is a photosensitive polyamic-acid ester composition characterized by including 30-600 mass parts.

(In the formula, X is a tetravalent aromatic group in which two benzene rings are bonded by an oxy group, R and R ′ are each independently a monovalent group having an olefinic double bond; "Is a linear or branched alkyl group or alkoxy group having 1 to 44 carbon atoms.)
The R ″ group in the general formula (1) is preferably a methyl group.

In the second aspect of the present invention, (a) a step of applying the photosensitive polyamic acid ester composition of the present invention to a substrate and drying, (b) a coating film by ultraviolet rays through a photomask or reticle having a pattern. A step of dissolving and removing unexposed portions with a solvent after exposure to obtain a polyamic acid ester pattern; and (c) a step of obtaining a polyimide pattern by heat curing the polyamic acid ester pattern. This is a method for forming a polyimide pattern.
A third aspect of the present invention is a semiconductor device having a polyimide pattern formed by the method for forming a polyimide pattern according to the second aspect of the present invention.

  INDUSTRIAL APPLICABILITY According to the present invention, a photosensitive polyamic acid ester composition capable of providing a polyimide pattern with a wide film thickness area capable of i-line exposure and high resolution, a method for forming a polyimide pattern using the photosensitive composition, and the polyimide pattern Can be provided.

（式中、Ｘは２個のベンゼン環をオキシ基で結合した４価の芳香族基であり、Ｒ及びＲ’はそれぞれ独立してオレフィン性二重結合を有する１価の基であり、Ｒ" は炭素数１〜４４の直鎖あるいは分岐のアルキル基あるいはアルコキシ基である。）
上記ポリアミド酸エステルにおいて、その繰り返し単位中のＸ基は、テトラカルボン酸ジエステルの原料として用いるテトラカルボン酸誘導体に由来する基である。
好ましいテトラカルボン酸誘導体の例としては、４，４’−オキシジフタル酸二無水物が挙げられる。 Hereinafter, the present invention will be described in more detail.
<Photosensitive polyamic acid ester composition>
(A) Polyamic acid ester The polyamic acid ester which is a component of the composition of the present invention is a polyamic acid ester comprising a repeating unit obtained by condensing a tetracarboxylic acid diester represented by the following general formula (1) and a diamine. .

(In the formula, X is a tetravalent aromatic group in which two benzene rings are bonded by an oxy group, R and R ′ are each independently a monovalent group having an olefinic double bond; "Is a linear or branched alkyl group or alkoxy group having 1 to 44 carbon atoms.)
In the polyamic acid ester, the X group in the repeating unit is a group derived from a tetracarboxylic acid derivative used as a raw material for the tetracarboxylic acid diester.
Examples of preferred tetracarboxylic acid derivatives include 4,4′-oxydiphthalic dianhydride.

  Examples of preferred diamines include 4,4'-diamino-3,3'-dimethyldiphenylmethane, 4,4'-diamino-3,3'-diethyldiphenylmethane, 4,4'-diamino-3,3'-di -N-propyldiphenylmethane, 4,4'-diamino-3,3'-di-isopropyldiphenylmethane, 4,4'-diamino-3,3'-di-n-butyldiphenylmethane, 4,4'-diamino-3 , 3′-di-isobutyldiphenylmethane, 4,4′-diamino-3,3′-di-tert-butyldiphenylmethane, 4,4′-diamino-3,3′-dimethoxydiphenylmethane, 4,4′-diamino- 3,3′-diethoxydiphenylmethane, 4,4′-diamino-3,3′-di-n-propoxydiphenylmethane, 4,4′-diamino-3 3'-diisopropoxydiphenylmethane, 4,4'-diamino-3,3'-di-n-butoxydiphenylmethane, 4,4'-diamino-3,3'-diisobutoxydiphenylmethane, 4,4'-diamino- 3,3′-di-tert-butoxydiphenylmethane and the like can be mentioned. Among these, 4,4'-diamino-3,3'-dimethyldiphenylmethane is particularly preferable.

In the synthesis of the polyamic acid ester, usually, a method in which a tetracarboxylic acid diester obtained by carrying out an esterification reaction of a tetracarboxylic dianhydride is directly subjected to a condensation reaction with a diamine can be preferably used.
Alcohols used in the diesterification reaction of the tetracarboxylic dianhydride are alcohols having an olefinic double bond. Specifically, 2-methacryloyloxyethyl alcohol, 2-acryloyloxyethyl alcohol, 1-acryloyloxy-2-propyl alcohol, 2-methacrylamide ethyl alcohol, 2-acrylamidoethyl alcohol, methylol vinyl ketone, 2-hydroxyethyl Examples include vinyl ketone, allyl alcohol, and 2-hydroxyethyl methacrylate. These alcohols can be used alone or in combination of two or more.
Further, as described in JP-A-06-080776, 1 to 30 moles of methyl alcohol, ethyl alcohol, n-propyl alcohol, and isopropyl alcohol are mixed with 100 moles of the alcohol having the olefinic double bond. It can also be used.

Theoretically, the amount of alcohols used for the diesterification of tetracarboxylic dianhydride is 1.0 equivalent per 1.0 equivalent of tetracarboxylic dianhydride (2. In the present invention, when a tetracarboxylic acid diester is synthesized using an alcohol such that 1.01 to 1.10 equivalents per 1.0 equivalent of tetracarboxylic dianhydride, Since the storage stability of the resulting photosensitive polyamic acid ester composition is improved, it is preferable.
In the composition of the present invention, the polyamic acid ester obtained by condensing the specific tetracarboxylic acid diester and the specific diamine described above balances thick film i-line curability and high resolution with other performances. Can take.
The molar ratio of the tetracarboxylic acid diester and the diamine used for the synthesis of the polyamic acid ester is preferably around 1.0, but in the range of 0.7 to 1.3 depending on the molecular weight of the target polyamic acid ester. Can be used.
As a specific method for synthesizing the polyamic acid ester used in the present invention, a conventionally known method can be employed. For this, for example, as shown in WO 00/43439, a tetracarboxylic acid diester is once converted into a tetracarboxylic acid diester diacid chloride, and the tetracarboxylic acid diester diacid chloride and diamine are made basic. Examples include a method of synthesizing a polyamic acid ester by subjecting it to a condensation reaction in the presence of a compound, and a method of synthesizing a polyamic acid ester by a method of subjecting a tetracarboxylic acid diester and a diamine to a condensation reaction in the presence of an organic dehydrating agent. .
Examples of organic dehydrators include dicyclohexylcarbodiimide (DCC), diethylcarbodiimide, diisopropylcarbodiimide, ethylcyclohexylcarbodiimide, diphenylcarbodiimide, 1-ethyl-3- (3-dimethylaminopropyl) carbodiimide, 1-cyclohexyl-3- (3 -Dimethylaminopropyl) carbodiimide hydrochloride, carbodiimide and the like.
The weight average molecular weight of the polyamic acid ester used in the present invention is preferably 8000 to 150,000, and more preferably 9000 to 50000.

(B) Photoinitiator Examples of the photoinitiator that is a component of the photosensitive polyamic acid ester composition of the present invention include benzophenone, methyl o-benzoylbenzoate, 4-benzoyl-4′-methyldiphenylketone, and dibenzyl. Ketones, benzophenone derivatives such as fluorenone, 2,2′-diethoxyacetophenone, and acetophenone derivatives such as 2-hydroxy-2-methylpropiophenone, 1-hydroxycyclohexyl phenyl ketone, thioxanthone, 2-methylthioxanthone, 2- Thioxanthone derivatives such as isopropylthioxanthone and diethylthioxanthone, benzyl derivatives such as benzyl, benzyldimethyl ketal and benzyl-β-methoxyethyl acetal, benzoin derivatives such as benzoin methyl ether, 2 Azides such as 6-di (4′-diazidobenzal) -4-methylcyclohexanone and 2,6′-di (4′-diazidobenzal) cyclohexanone, 1-phenyl-1,2-butanedione-2- (O-methoxy) Carbonyl) oxime, 1-phenylpropanedione-2- (O-methoxycarbonyl) oxime, 1-phenylpropanedione-2- (O-ethoxycarbonyl) oxime, 1-phenylpropanedione-2- (O-benzoyl) oxime Oximes such as 1,3-diphenylpropanetrione-2- (O-ethoxycarbonyl) oxime and 1-phenyl-3-ethoxypropanetrione-2- (O-benzoyl) oxime, N such as N-phenylglycine -Peroxides such as arylglycines, benzoyl peroxide, and Aromatic biimidazoles, and the like titanocene. Among these, the above oximes are preferable in terms of thick film i-line curability and photosensitivity.
As for the addition amount of these photoinitiators, 1-15 mass parts is preferable with respect to 100 mass parts of (A) polyamic-acid ester. By adding 1 part by mass or more of the initiator to 100 parts by mass of the polyamic acid ester, it is possible to obtain a composition having excellent photosensitivity and by adding 15 parts by mass or less of the initiator, it is possible to obtain a composition having excellent thick film i-line curability.

(C) Solvent As the solvent that is a component of the polyamic acid ester composition of the present invention, a polar organic solvent is preferably used from the viewpoint of solubility in the components (A) and (B). Specifically, N, N-dimethylformamide, N-methylpyrrolidone, N-ethyl-2-pyrrolidone, N, N-dimethylacetamide, diethylene glycol dimethyl ether, cyclopentanone, γ-butyrolactone, α-acetyl-γ-butyrolactone , Tetramethylurea, 1,3-dimethyl-2-imidazolinone, N-cyclohexyl-2-pyrrolidone and the like, and these can be used alone or in combination of two or more.
These solvents can be used in the range of 30 to 600 parts by mass with respect to 100 parts by mass of the (A) polyamic acid ester, depending on the coating film thickness and viscosity.
Furthermore, in order to improve the storage stability of the polyamic acid ester composition of the present invention, it is preferable to contain alcohols in the organic solvent used as the solvent.

The alcohol that can be used is not particularly limited as long as it has an alcoholic hydroxyl group in the molecule. Specific examples thereof include methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, and n-butyl. Lactic acid esters such as alcohol, isobutyl alcohol, tert-butyl alcohol, ethyl lactate, propylene glycol-1-methyl ether, propylene glycol-2-methyl ether, propylene glycol-1-ethyl ether, propylene glycol-2-ethyl ether, Propylene glycol monoalkyl ethers such as propylene glycol-1- (n-propyl) ether and propylene glycol-2- (n-propyl) ether, ethylene glycol methyl ether, ethylene glycol Le ethyl ether, mono-alcohols such as ethylene glycol -n- propyl ether, 2-hydroxyisobutyric acid esters, ethylene glycol, di alcohols such as propylene glycol, and the like. Among these, lactic acid esters, propylene glycol monoalkyl ethers, 2-hydroxyisobutyric acid esters, and ethyl alcohol are preferable. Particularly, ethyl lactate, propylene glycol-1-methyl ether, propylene glycol-1-ethyl ether, propylene Glycol-1- (n-propyl) ether is more preferred.
The alcohol content in the total solvent is preferably 5 to 50% by weight, more preferably 10 to 30% by weight. When the alcohol content is 5% by weight or more, the storage stability of the polyamic acid ester composition is good, and when it is 50% by weight or less, the solubility of the polyamic acid ester as component (A) is good. .

(D) Other components A compound having a photopolymerizable unsaturated double bond can be added to the photosensitive resin composition of the present invention as necessary.
As such a compound, a (meth) acrylic compound that can be polymerized by a photopolymerization initiator is preferable. For example, polyethylene glycol diacrylate (numbers 2 to 20 of each ethylene glycol unit), polyethylene glycol dimethacrylate (of each ethylene glycol unit). 2-20), poly (1,2-propylene glycol) diacrylate, poly (1,2-propylene glycol) dimethacrylate, pentaerythritol diacrylate, pentaerythritol dimethacrylate, glycerol diacrylate, glycerol dimethacrylate, dipenta Erythritol hexaacrylate, methylenebisacrylamide, N-methylolacrylamide, ethylene glycol diglycidyl ether-methacrylic acid adduct, glycero And bisphenol A diglycidyl ether-acrylic acid adduct, bisphenol A diglycidyl ether-methacrylic acid adduct, and N, N′-bis (2-methacryloyloxyethyl) urea. Moreover, in using these, you may use individually or in mixture of 2 or more types as needed. The addition amount is preferably 1 to 50 parts by mass with respect to 100 parts by mass of (A) polyamic acid ester.

A sensitizer can also be added to the photosensitive polyamic acid ester composition of the present invention in order to further improve the photosensitivity.
Examples of the sensitizer include Michler's ketone, 4,4′-bis (diethylamino) benzophenone, 2,5-bis (4′-diethylaminobenzal) cyclopentane, and 2,6-bis (4′-diethylaminobenzal). Cyclohexanone, 2,6-bis (4′-diethylaminobenzal) -4-methylcyclohexanone, 4,4′-bis (dimethylamino) chalcone, 4,4′-bis (diethylamino) chalcone, p-dimethylaminocinnamyl Denindanone, p-dimethylaminobenzylideneindanone, 2- (p-dimethylaminophenylbiphenylene) -benzothiazole, 2- (p-dimethylaminophenylvinylene) benzothiazole, 2- (p-dimethylaminophenylvinylene) iso Naphthothiazole, 1,3-bis (4′-dimethyla Minobenzal) acetone, 1,3-bis (4′-diethylaminobenzal) acetone, 3,3′-carbonyl-bis (7-diethylaminocoumarin), 3-acetyl-7-dimethylaminocoumarin, 3-ethoxycarbonyl-7 -Dimethylaminocoumarin, 3-benzyloxycarbonyl-7-dimethylaminocoumarin, 3-methoxycarbonyl-7-diethylaminocoumarin, 3-ethoxycarbonyl-7-diethylaminocoumarin, N-phenyl-N'-ethylethanolamine, N- Phenyldiethanolamine, Np-tolyldiethanolamine, N-phenylethanolamine, 4-morpholinobenzophenone, isoamyl dimethylaminobenzoate, isoamyl diethylaminobenzoate, 2-mercaptobenzimidazole, 1-fur Nyl-5-mercaptotetrazole, 2-mercaptobenzothiazole, 2- (p-dimethylaminostyryl) benzoxazole, 2- (p-dimethylaminostyryl) benzthiazole, 2- (p-dimethylaminostyryl) naphtho (1, 2-d) thiazole, 2- (p-dimethylaminobenzoyl) styrene, benzotriazole, 5-methylbenzotriazole, 5-phenyltetrazole and the like. These may be used alone or in combination of 2 to 5 types.

In these, it is preferable to use combining the sensitizer which has a mercapto group, and the sensitizer which has a dialkylaminophenyl group from the point of photosensitivity. Moreover, when using a copper substrate as a base material, it is preferable to use combining the sensitizer which has a triazole ring, and the sensitizer which has a dialkylaminophenyl group. It is preferable that 0.1-10 mass parts is used for a sensitizer with respect to 100 mass parts of (A) polyamic-acid ester.
In addition, an adhesion aid can be added to the photosensitive composition of the present invention in order to improve the adhesion to the substrate. Adhesion aids include γ-aminopropyldimethoxysilane, N- (β-aminoethyl) -γ-aminopropylmethyldimethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, γ-mercaptopropylmethyldimethoxysilane, 3- Methacryloxypropyldimethoxymethylsilane, 3-methacryloxypropyltrimethoxysilane, dimethoxymethyl-3-piperidinopropylsilane, diethoxy-3-glycidoxypropylmethylsilane, N- (3-diethoxymethylsilylpropyl) succinimide N- [3- (triethoxysilyl) propyl] phthalamic acid, benzophenone-3,3′-bis (N- [3-triethoxysilyl] propylamide) -4,4′-dicarboxylic acid, benzene-1, 4-bis (N- [3-triet Sisilyl] propylamide) -2,5-dicarboxylic acid, 3- (triethoxysilyl) propyl succinic anhydride, silane coupling agents such as N-phenylaminopropyltrimethoxysilane, and aluminum tris (ethylacetoacetate), Examples thereof include aluminum adhesion assistants such as aluminum tris (acetylacetonate) and ethyl acetoacetate aluminum diisopropylate.
In these, it is more preferable to use a silane coupling agent from the point of adhesive force. The addition amount of the adhesion assistant is preferably in the range of 0.5 to 10 parts by mass with respect to (A) 100 parts by mass of the polyamic acid ester.

In addition, a thermal polymerization inhibitor can be added to the photosensitive polyamic acid ester composition of the present invention in order to improve the viscosity of the composition solution during storage and the stability of photosensitivity.
Examples of thermal polymerization inhibitors include hydroquinone, N-nitrosodiphenylamine, p-tert-butylcatechol, phenothiazine, N-phenylnaphthylamine, ethylenediaminetetraacetic acid, 1,2-cyclohexanediaminetetraacetic acid, glycol etherdiaminetetraacetic acid, 2,6 -Di-tert-butyl-p-methylphenol, 5-nitroso-8-hydroxyquinoline, 1-nitroso-2-naphthol, 2-nitroso-1-naphthol, 2-nitroso-5- (N-ethyl-N- Sulfopropylamino) phenol, N-nitroso-N-phenylhydroxylamine ammonium salt, N-nitroso-N (1-naphthyl) hydroxylamine ammonium salt and the like are used.
As a quantity of the thermal-polymerization inhibitor added to a photosensitive polyamic-acid ester composition, the range of 0.005-5 mass parts is preferable with respect to 100 mass parts of (A) polyamic-acid ester.
In the polyamic acid ester composition of the present invention, an organic titanium compound can be added as a component for improving heat resistance and chemical resistance. The usable organic titanium compound is not particularly limited as long as the organic chemical substance is bonded to the titanium atom through a covalent bond or an ionic bond.

Specific examples of organotitanium compounds that can be used in the present invention are first titanocenes. Preferable titanocenes include, for example, pentamethylcyclopentadienyl titanium trimethoxide. In this case, if titanocenes that function as a photoinitiator such as bis (2,6-difluoro-3- (1-hydropyrrol-1-yl) phenyl) titanocene are used, there are others that may be used in the present invention. In some cases, it is difficult to obtain a good pattern due to interference with the photoinitiator, and titanocenes that do not function as a photoinitiator are more preferable.
Another specific example of the organic titanium compound that can be used in the present invention is a titanium chelate. In the present invention, among titanium chelates, a compound having two or more alkoxy groups is more preferable because the stability of the composition and a good pattern can be obtained. Preferred titanium chelates include, for example, titanium bis (triethanolamine) diisopropoxide, titanium di (n-butoxide) (bis-2,4-pentandionate), titanium diisopropoxide (bis-2, 4-pentanedionate), titanium diisopropoxide bis (tetramethylheptanedionate), titanium diisopropoxide bis (ethyl acetoacetate).

Other specific examples of the organic titanium compounds that can be used in the present invention include titanium tetra (n-butoxide), titanium tetraethoxide, titanium tetra (2-ethylhexoxide), and titanium tetraisobutene. Toxide, Titanium tetraisopropoxide, Titanium tetramethoxide, Titanium tetramethoxypropoxide, Titanium tetramethylphenoxide, Titanium tetra (n-nonyloxide), Titanium tetra (n-propoxide), Titanium tetrastearyloxide, Titanium Tetraalkoxides such as tetrakis (bis-2,2- (allyloxymethyl) butoxide), titanium tris (dioctyl phosphate) isopropoxide, titanium tris (dodecyl) Nene sulfonate) monoalkoxides such as isopropoxide, titanium oxide bis (pentanedionate), titanium oxide bis (tetramethylheptanedionate), titanium oxides such as phthalocyanine titanium oxide, titanium tetraacetylacetonate And the like, and titanate coupling agents such as isopropyltridodecylbenzenesulfonyl titanate.
The addition amount of these organic titanium compounds is preferably 0.3 to 10 parts by mass, more preferably 0.5 to 2 parts by mass with respect to 100 parts by mass of the (A) polyamic acid ester. When the addition amount is 0.3 parts by mass or more, desired heat resistance and chemical resistance are exhibited, and when it is 10 parts by mass or less, the storage stability is excellent.

<Polyimide pattern forming method and semiconductor device>
In another aspect of the present invention, a method for forming a polyimide pattern on a substrate including the following steps is provided.
(A) A step of applying the photosensitive polyamic acid ester composition to a substrate and drying it;
(B) A step of obtaining a polyamic acid ester pattern by exposing the coating film to ultraviolet rays through a photomask or reticle having a pattern and then dissolving and removing the unexposed portion with a solvent;
(C) A step of obtaining a polyimide pattern by heat curing the polyamic acid ester pattern.
Examples of the base material that can be used in the present invention include a silicon wafer, a metal such as copper, glass, a semiconductor, a metal oxide insulating film, and silicon nitride. Preferably, a silicon wafer or a copper substrate is used.

In the present invention, as a method of applying the photosensitive polyamic acid ester composition on the substrate, methods conventionally used for applying the photosensitive resin composition, for example, spin coater, bar coater, blade coater, curtain For example, a coating method using a coater or a screen printer, a spray coating method using a spray coater, or the like can be used.
As a method for drying the coating film, methods such as air drying, heat drying with an oven or hot plate, and vacuum drying are used. Moreover, it is desirable that the coating film be dried under conditions such that imidation of the polyamic acid ester in the photosensitive polyamic acid ester composition does not occur. Specifically, when performing air drying or heat drying, it can be performed at 20 ° C. to 140 ° C. for 1 minute to 1 hour. As for the thickness of the coating film after drying, 5-50 micrometers is preferable.

The coating film thus obtained is exposed with an ultraviolet light source or the like through a photomask or reticle having a pattern, using an exposure apparatus such as a contact aligner, mirror projection, or stepper, and then developed.
The developer used for development is preferably a good solvent for the polyamic acid ester composition or a combination of a good solvent and a poor solvent. As the good solvent, N-methylpyrrolidone, N-cyclohexyl-2-pyrrolidone, N, N-dimethylacetamide, cyclopentanone, cyclohexanone, γ-butyrolactone, α-acetyl-γ-butyrolactone, and the like are preferable. Toluene, xylene, methanol, ethanol, isopropyl alcohol, ethyl lactate, propylene glycol methyl ether acetate and water are used. When a good solvent and a poor solvent are mixed and used, the ratio of the poor solvent to the good solvent is adjusted depending on the solubility of the polymer. Moreover, several types of solvents can be used in combination.

As a method used for development, an arbitrary method can be selected from conventionally known photoresist development methods such as a rotary spray method, a paddle method, and an immersion method involving ultrasonic treatment.
The polyamic acid ester pattern obtained as described above is heated to dilute the photosensitive component, and is converted into a polyimide pattern by polyimidation. Various methods such as a method using a hot plate, a method using an oven, and a method using a temperature rising oven capable of setting a temperature program can be selected as the method for heat curing. Heating can be performed at 280 ° C. to 450 ° C. for 30 minutes to 5 hours. Air may be used as the atmospheric gas for heat curing, and an inert gas such as nitrogen or argon may be used.

Thus, a polyimide pattern having a thickness after curing of 4 to 30 μm and an aspect ratio (thickness / resolution after coating / drying) of 1 or more can be obtained. In particular, as shown in the examples below, a polyimide pattern having a thickness after curing of 20 to 30 μm and an aspect ratio of 1 or more, which was difficult to obtain with a conventional i-line curable polyimide precursor composition, was formed. can do.
In still another aspect of the present invention, a semiconductor device having a polyimide pattern formed by the above-described method is provided. In particular, it is possible to obtain a semiconductor device having a polyimide pattern with a thickness of 20 to 30 μm and an aspect ratio of 1 or more on a silicon wafer, which is difficult to obtain with a conventional i-line curable polyimide precursor composition. In addition, a semiconductor device having a polyimide pattern with a thickness of 15 to 25 μm and an aspect ratio of 1 or more on a copper substrate can be obtained. The semiconductor device can be obtained by combining the above-described polyimide pattern forming method with a known method for manufacturing a semiconductor device.

The present invention will be specifically described below with reference to examples and comparative examples.
In Examples, Comparative Examples and Reference Examples, the physical properties of the photosensitive polyamic acid ester composition were measured and evaluated according to the following methods.
(1) Weight average molecular weight The weight average molecular weight (Mw) of each polyamic acid ester was measured by the gel permeation chromatography method (standard polystyrene conversion).
(2) Resolution and accuracy of polyimide pattern The photosensitive polyamic acid ester composition was spin-coated on a 5-inch silicon wafer or a copper substrate and dried to form a 10 μm thick coating film. This coating film was irradiated with energy of 300 mJ / cm ² using an i-line stepper NSR1755i7B (Nikon Corporation, Japan) using a reticle with a test pattern. Subsequently, the coating film formed on the wafer is spray-developed with a developing machine (D-SPIN636 type, manufactured by Dainippon Screen Mfg. Co., Ltd.) using cyclopentanone, rinsed with propylene glycol methyl ether acetate, and polyamide An acid ester pattern was obtained.
The wafer on which the pattern is formed is heat-treated in a nitrogen atmosphere at 200 ° C. for 1 hour and then at 350 ° C. for 2 hours using a temperature-programmed cure furnace (VF-2000 type, manufactured by Koyo Lindberg, Japan). Thus, a polyimide pattern having a thickness of 5 μm was obtained on the silicon wafer.

About each obtained pattern, the width | variety of the pattern shape and the pattern part was observed under the optical microscope, and the resolution was calculated | required. Regarding the resolution, a pattern having a plurality of openings with different areas is formed by the above method by exposing through a reticle with a test pattern, and the area of the obtained pattern opening is equal to the corresponding pattern mask opening area. If it is 1/2 or more, it is considered that it has been resolved, and the length of the opening side of the mask corresponding to the resolved opening having the smallest area is taken as the resolution. The resolution is good if it is 10 μm or less, that is, if the aspect ratio (film thickness after coating / drying) is 1 or more. Similarly, evaluation of the coating film having a film thickness of 50 μm or 40 μm after coating and drying was also carried out. Moreover, the precision of the polyimide pattern was evaluated based on the following criteria.
“Good”: the pattern cross section is not slid, undercut, swelling, bridging does not occur, and the aspect ratio is 1 or more. Furthermore, the pattern shape does not change during heat curing.
“Bad” ... Any one of the above conditions is not satisfied.

Reference Example 1 (Synthesis of polyamic acid ester A)
Put 155.1 g of 4,4′-oxydiphthalic dianhydride (ODPA) in a 2 liter separable flask, add 131.2 g of 2-hydroxyethyl methacrylate (HEMA) and 400 ml of γ-butyrolactone, and stir at room temperature. While stirring, 81.5 g of pyridine was added to obtain a reaction mixture. After completion of the exothermic reaction, the mixture was allowed to cool to room temperature and left for 16 hours.
Next, under ice cooling, a solution prepared by dissolving 206.3 g of dicyclohexylcarbodiimide (DCC) in 180 ml of γ-butyrolactone was added to the reaction mixture over 40 minutes with stirring, followed by 3,3′-dimethyl-4,4. A suspension of 105.1 g of '-diaminodiphenylmethane in 350 ml of γ-butyrolactone was added over 60 minutes with stirring. After further stirring for 2 hours at room temperature, 30 ml of ethyl alcohol was added and stirred for 1 hour, and then 400 ml of γ-butyrolactone was added. The precipitate generated in the reaction mixture was removed by filtration to obtain a reaction solution.
The obtained reaction solution was added to 3 liters of ethyl alcohol to produce a precipitate consisting of a crude polymer. The produced crude polymer was separated by filtration and dissolved in 1.5 liter of tetrahydrofuran to obtain a crude polymer solution. The obtained crude polymer solution was dropped into 28 liters of water to precipitate a polymer, and the obtained precipitate was filtered off and then vacuum dried to obtain a powdery polymer (polyamic acid ester A). When the molecular weight of the polyamic acid ester A was measured by gel permeation chromatography (standard polystyrene conversion), the weight average molecular weight (Mw) was 23,000.

Reference Example 2 (Synthesis of polyamic acid ester B)
Put 155.1 g of 4,4′-oxydiphthalic dianhydride (ODPA) in a 2 liter separable flask, add 131.2 g of 2-hydroxyethyl methacrylate (HEMA) and 400 ml of γ-butyrolactone, and stir at room temperature. While stirring, 81.5 g of pyridine was added to obtain a reaction mixture. After completion of the exothermic reaction, the mixture was allowed to cool to room temperature and left for 16 hours.
Next, under ice cooling, a solution prepared by dissolving 206.3 g of dicyclohexylcarbodiimide (DCC) in 180 ml of γ-butyrolactone was added to the reaction mixture over 40 minutes with stirring, followed by 4,4′-diaminodiphenyl ether (DADPE). A suspension of 93.0 g in γ-butyrolactone 350 ml was added over 60 minutes with stirring. After further stirring for 2 hours at room temperature, 30 ml of ethyl alcohol was added and stirred for 1 hour, and then 400 ml of γ-butyrolactone was added. The precipitate generated in the reaction mixture was removed by filtration to obtain a reaction solution.
The obtained reaction solution was added to 3 liters of ethyl alcohol to produce a precipitate consisting of a crude polymer. The produced crude polymer was separated by filtration and dissolved in 1.5 liter of tetrahydrofuran to obtain a crude polymer solution. The obtained crude polymer solution was dropped into 28 liters of water to precipitate a polymer, and the resulting precipitate was filtered off and dried in vacuo to obtain a powdery polymer (polyamic acid ester B). When the molecular weight of the polyamic acid ester B was measured by gel permeation chromatography (standard polystyrene conversion), the weight average molecular weight (Mw) was 20000.

Reference Example 3 (Synthesis of polyamic acid ester C)
As the tetracarboxylic acid, 3,3′4,4′-biphenyltetracarboxylic dianhydride and 2,2-bis (4-amino-3-methylphenyl) hexafluoropropane as the diamine are used. The polyamic acid ester C was obtained by the reaction according to the method described in Example 1. When the molecular weight of the polyamic acid ester C was measured by gel permeation chromatography (standard polystyrene conversion), the weight average molecular weight (Mw) was 25,000.

<Example 1>
Using the polyamic acid ester A, a photosensitive polyamic acid ester composition was prepared by the following method, and the prepared composition was evaluated.
100 g of polyamic acid ester A, 4 g of diphenylpropanetrione-2- (o-ethoxycarbonyl) oxime (photoinitiator), 4 g of tetraethylene glycol dimethacrylate, 1 g of 1-phenyl-5-mercaptotetrazole, 4 g of N-phenyldiethanolamine, N -It was dissolved in a mixed solvent consisting of 80 g of N-methylpyrrolidone (NMP) and 20 g of ethyl lactate together with 3 g of [3- (triethoxysilyl) propyl] phthalamic acid and 0.05 g of 2-nitroso-1-naphthol. The viscosity of the obtained solution was adjusted to about 75 poise by further adding a small amount of the mixed solvent to obtain a photosensitive polyamic acid ester composition.
The resolution of the polyimide coating film obtained by coating, drying, exposing, developing and heat-treating the composition on a silicon wafer according to the above-described method is 8 μm when the film thickness after coating and drying is 10 μm, and the film thickness after curing. Was 5 μm. The resolution when the film thickness after coating and drying was 50 μm was 40 μm, and the film thickness after curing was 30 μm. Each of them satisfied an aspect ratio of 1 or more, and the pattern accuracy was good.

<Example 2>
Using the polyamic acid ester A, a photosensitive polyamic acid ester composition was prepared by the following method, and the prepared composition was evaluated.
100 g of polyamic acid ester A was added to 4 g of diphenylpropanetrione-2- (o-ethoxycarbonyl) oxime (photoinitiator), 6.5 g of tetraethylene glycol dimethacrylate, 1 g of benzotriazole, 6.5 g of N-phenyldiethanolamine, N- [ Along with 3 g of 3- (triethoxysilyl) propyl] phthalamic acid and 0.05 g of 2-nitroso-1-naphthol, it was dissolved in a mixed solvent consisting of 80 g of N-methylpyrrolidone (NMP) and 20 g of ethyl lactate. The viscosity of the obtained solution was adjusted to about 75 poise by further adding a small amount of the mixed solvent to obtain a photosensitive polyamic acid ester composition.
The resolution of the polyimide coating film obtained by coating, drying, exposing, developing and heat-treating the composition on a copper substrate according to the above-described method is 8 μm when the film thickness after coating and drying is 10 μm, and the film thickness after curing. Was 5 μm. The resolution when the film thickness after coating and drying was 40 μm was 30 μm, and the film thickness after curing was 24 μm. Each of them satisfied an aspect ratio of 1 or more, and the pattern accuracy was good.

<Comparative Example 1>
A photosensitive polyamic acid ester composition was prepared and evaluated in the same manner as in Example 1 except that the polyamic acid ester B was used instead of the polyamic acid ester A.
The resolution of the polyimide coating film obtained by coating, drying, exposing, developing and heat-treating the composition on a silicon wafer according to the above-described method is 8 μm when the film thickness after coating and drying is 10 μm, and the film thickness after curing. Was 5 μm, the aspect ratio was 1 or more, and the pattern accuracy was good. However, when the film thickness after coating and drying was 50 μm, an undercut occurred and a pattern satisfying the necessary conditions could not be obtained.

<Comparative example 2>
A photosensitive polyamic acid ester composition was prepared and evaluated in the same manner as in Example 2 except that the polyamic acid ester B was used instead of the polyamic acid ester A.
The resolution of the polyimide coating film obtained by coating, drying, exposing, developing and heat-treating the composition on a copper substrate according to the above-described method is 8 μm when the film thickness after coating and drying is 10 μm, and the film thickness after curing. Was 5 μm, the aspect ratio was 1 or more, and the pattern accuracy was good. However, when the film thickness after coating and drying was 40 μm, an undercut occurred, and a pattern satisfying the necessary conditions could not be obtained.

<Comparative Example 3>
A photosensitive polyamic acid ester composition was prepared and evaluated in the same manner as in Example 1 except that the polyamic acid ester C was used instead of the polyamic acid ester A.
The resolution of the polyimide coating film obtained by coating, drying, exposing, developing and heat-treating the composition on a silicon wafer according to the above-described method is 8 μm when the film thickness after coating and drying is 10 μm, and the film thickness after curing. Was 5 μm, the aspect ratio was 1 or more, and the pattern accuracy was good. However, when the film thickness after coating and drying was 50 μm, an undercut occurred and a pattern satisfying the necessary conditions could not be obtained.

<Comparative example 4>
A photosensitive polyamic acid ester composition was prepared and evaluated in the same manner as in Example 2 except that the polyamic acid ester C was used instead of the polyamic acid ester A.
The resolution of the polyimide coating film obtained by coating, drying, exposing, developing and heat-treating the composition on a copper substrate according to the above-described method is 8 μm when the film thickness after coating and drying is 10 μm, and the film thickness after curing. Was 5 μm, the aspect ratio was 1 or more, and the pattern accuracy was good. However, when the film thickness after coating and drying was 40 μm, an undercut occurred, and a pattern satisfying the necessary conditions could not be obtained.

  The composition of the present invention can be suitably used in the fields of surface protective films and interlayer insulating films of semiconductor devices.

Claims (4)

(A) 100 mass parts of polyamic acid ester which consists of a repeating unit represented by following General formula (1), (B) 1-15 mass parts of photoinitiators, and (C) 30-600 mass parts of solvent are included. The photosensitive polyamic-acid ester composition characterized by the above-mentioned.

(In the formula, X is a tetravalent aromatic group in which two benzene rings are bonded by an oxy group, R and R ′ are each independently a monovalent group having an olefinic double bond; "Is a linear or branched alkyl group or alkoxy group having 1 to 44 carbon atoms.)   The photosensitive polyamic acid ester composition according to claim 1, wherein the R "group in the general formula (1) is a methyl group.   (A) a step of applying the photosensitive polyamic acid ester composition according to claim 1 or 2 to a substrate and drying; (b) after exposing the coating film with ultraviolet rays through a photomask or reticle having a pattern; A polyimide comprising: a step of dissolving and removing unexposed portions with a solvent to obtain a polyamic acid ester pattern; and (c) a step of obtaining a polyimide pattern by heating and curing the polyamic acid ester pattern. Pattern formation method.   A semiconductor device comprising a polyimide pattern formed by the method for forming a polyimide pattern according to claim 3.