JPH06282081A - Method for forming pattern - Google Patents

Abstract

(57) [Summary] [Structure] In a method for forming a pattern from a photocrosslinkable polymer composition containing a polyimide precursor, 10% by volume or more of the following formula [II] is shown after removing an unexposed portion with a developer. A pattern forming method comprising: cleaning with a rinse liquid containing a compound that is liquid at room temperature. [Effect] It becomes possible to provide an extremely high-resolution pattern that is free from residues and surface damage, which have been problems in the past.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a predetermined pattern from a photocrosslinking polymerization composition used as a polyimide precursor when forming an interlayer insulating film in the semiconductor industry.

[0002]

2. Description of the Related Art In recent years, in the semiconductor industry, as an insulating film or a passivation film for a solid element, or as an interlayer insulating film for an integrated circuit or a multilayer printed wiring board, a polyimide having high heat resistance and excellent in forming a step as compared with an inorganic substance is formed. Resins having heterocycles such as resins have come to be used. When forming an interlayer insulating film, it is necessary to provide via holes for conducting the upper and lower layers, and as a method therefor, a pattern forming method using a photosensitive polyimide having excellent processability has been proposed. There is. Among these materials used for pattern formation, the photocrosslinkable polymer composition having a repeating unit represented by the formula [I] is excellent in forming a thick film, and has no film slippage in the exposed area during development. It has the excellent characteristics of The pattern forming method using the composition is performed in the following process order, for example.

1 Coating: The precursor composition varnish is coated on a predetermined substrate. 2 Drying: The solvent is evaporated to form a coating film of the precursor composition. 3 Exposure: Exposure is performed using a predetermined photomask. 4 Development: The unexposed area is dissolved and removed with a soluble developing solution, and rinsed with a rinse solution.

5 Thermosetting: By heating, it is converted into a polyimide resin to obtain a predetermined pattern. As a conventional developing / rinsing solution in a series of steps, a developing solution of a good solvent alone of the precursor or a mixture of a good solvent and a poor solvent and a rinse solution of a poor solvent of the precursor alone or a mixture of a poor solvent are used. . For example, a developing solution of dimethylacetamide alone, a developing solution of a mixture of dimethylformamide and xylene in a ratio of 1: 1 (volume ratio), isopropyl alcohol alone or a mixture of isopropyl alcohol and xylene of 1:
A 1 (volume ratio) mixed rinse solution is used.

[0005]

When a pattern is formed by the method as described above, the pattern may drip or a thin film may remain in the lower portion of the via hole after development depending on the combination and balance of the developing solution and the rinsing solution. Rinsing shock, which is a poor solvent, may cause a rinsing shock, and the residue may adhere to the entire surface or a part of the substrate, or the surface may be roughened. In addition, xylene, which is often used as a poor solvent, has recently been used in a decreasing amount due to environmental hygiene problems.

[0006]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies to solve the problems of the prior art described above, and as a result, by washing with a rinse liquid described below,
It was possible to obtain a good pattern in which the pattern did not drip, a thin film did not remain at the bottom of the via hole after development, scum due to the rinse shock did not occur, and the exposed portion was not damaged.
That is, the present invention is a method of forming a predetermined pattern from a photosensitive composition containing a photocrosslinkable polymer having a repeating unit represented by formula (1) [I] through an exposure step and a development step, in which a developer is used. After removing the unexposed portion, the pattern forming method is characterized by washing with a rinse liquid containing 10% by volume or more of a compound represented by the following formula [II] which is liquid at room temperature.

[0007] (X in the formula is a (2 + n) -valent carbocyclic or heterocyclic,
Y is a (2 + m) -valent carbon R is a group having a carbon-carbon double bond, W is a group capable of reacting with the carbonyl group of -COR by heat treatment to form a ring,
n is 1 or 2, m is 0, 1 or 2, and CO
R and Z are in an ortho position or a peri position. ) (R ₁ , R ₂ and R ₃ are H or an alkyl group having 1 to 8 carbon atoms.) X in the formula [I] used in the present invention is a chemical structure excluding the carboxyl group of the aromatic tetracarboxylic acid. Examples thereof include acid anhydrides such as pyromellid acid anhydride and benzophenone tetracarboxylic acid anhydride. Y represents a chemical structure excluding the amino group of aromatic diamine, and examples thereof include diamines such as 4,4′-diaminodiphenyl ether and 4,4′-diaminodiphenyl sulfone. That is, the polymer of the formula [I] includes, but is not limited to, a polyimide precursor having a photosensitive group in a side chain of a repeating unit formed by polycondensation of an acid anhydride and a diamine.

The photosensitive group introduced into the precursor is a group having a carbon-carbon double bond which is dimerizable or polymerizable by light, such as vinyl group, allyl group, acryl group, methacryl group, cinnamyl group and maleimide. Groups having groups are preferred. The bonding form of the photosensitive group generally includes covalent bond such as ester bond and amide bond and ionic bond. Examples of the additives mixed for the purpose of improving the photosensitivity of the photocrosslinkable polymer having the repeating unit represented by the formula [I] include a photopolymerization initiator, a sensitizer and a photosensitive monomer.

The photopolymerization initiator and the sensitizer include, for example,
Benzophenone, benzophenones such as 4,4′-bis (dimethylamino) benzophenone, benzoin ether or anthraquinone, or thioxanthone derivative,
Bisazides such as 2,6-bis- (4'-diethylaminobenzal) -cyclohexanone, 1-phenyl-5-
Mercapto compounds such as mercaptotetrazole, oximes such as 1-phenyl-1,2-propanedione-2- (O-ethoxycarbonyl) -oxime, 2,4,5-
These are imidazoles such as triphenylimidazole dimer.

Further, as the photosensitive monomer, for example,
(Meth) acrylates such as trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, and dimethylaminoethyl methacrylate, mercapto compounds such as thioglycol, maleimides such as phenylsulfonylmaleimide, and isocyanates such as ethyl methacrylate isocyanate.

These additives are added to 100 parts by weight of the photocrosslinkable polymer.
It is preferable to add 0.1 to 50 parts by weight to parts by weight.
Good As the solvent, N, N'-dimethylformamide,
N, N'-dimethylacetamide, γ-butyrolacto
N, N-methylpyrrolidone, etc. are preferred, but not limited to
It is not something that can be done. As the compound represented by the formula [II]
Is preferably R₁ Is H, R₂Is CH₃, R ₃Has 1 carbon
Examples include lactate esters that are alkyl groups from 1 to 4
In addition, ethyl lactate is preferable in terms of environmental hygiene, but
It is not limited to these. When using a mixed solvent
If no residue remains after rinsing, the mixing amount is limited
It can be arbitrarily selected without.

The coating method on the substrate is typically performed by a spinner, a roll coater or the like, and examples of the substrate include a silicon wafer, ceramics and a copper plate. As a drying method, a hot plate, a circulation type oven or the like can be cited as a good example, and a drying temperature is 50 to 140 ° C.
More preferably, the temperature is 60 to 100 ° C. Although the drying time varies depending on the thickness and the drying method, it is considered that about 1 minute to 5 minutes is preferable on a hot plate.

As an exposure method, it is preferable to irradiate ultraviolet rays through a photomask with an exposure device used in a usual photoresist process. The exposure time varies depending on the type of the photocrosslinking polymer, the type of additives and the light intensity of the exposing machine, but generally, the optimum time may be selected from 0.1 second to 10 minutes. There is no problem as long as the treatment such as heat treatment after the exposure is carried out according to the performance of the varnish to be used, and the treatment is not particularly limited.

Examples of the developing solution include a good solvent for the polymer alone, and a mixed solvent in which a good solvent and a poor solvent are combined. Examples of the good solvent include N, N′-dimethylformamide, N, N′dimethylacetamide, cyclopentanone, N-methylpyrrolidone, γ-butyrolactone, and the like, as long as they dissolve the polymer,
It is not limited to these. Further, these may be a mixed system of two or more kinds. As the poor solvent, toluene, xylene, acetone, ethylbenzene, methyl cellosolve, ethyl acetate, isopropylbenzene, isopropyl alcohol,
Examples thereof include, but are not limited to, isobutyl alcohol and water. Further, there is no restriction on the amount ratio of these as long as the polymer can be dissolved therein.

The developed pattern image of the polymer composition is immediately washed with a rinse to remove the developer.
As the rinse liquid, the compound represented by the formula [II] is used.
A solvent containing at least 100 volumes but not less than 50 volumes, more preferably at least 100 volumes is used. When mixing, it is preferable to use a poor solvent for the polymer,
Examples include, but are not limited to, toluene, xylene, acetone, ethylbenzene, methyl cellosolve, ethyl acetate, isopropylbenzene, isopropyl alcohol, isobutyl alcohol, water and the like.

As the developing method, spray development, immersion development and ultrasonic development are mentioned as preferable examples, but the highest resolution is obtained by spray development. Also, when this method is selected, the ignition point of the developer and rinse solution,
Higher flash points are preferred. The conversion of the obtained polyimide precursor pattern into polyimide is performed by thermosetting at 200 ° C. to 500 ° C. for 5 minutes to 3 hours. Examples of the method include, but are not limited to, a circulation oven, a vertical thermosetting oven, and a hot blade.

[0017]

EXAMPLES Next, the present invention and its effects will be described by way of examples.

[0018]

Reference Example 1 27.0 g of pyromellitic anhydride and 27.0 g of 2-hydroxyethyl methacrylate were dissolved in 100 ml of γ-butyrolactone, and the mixture was stirred at room temperature for 15 hours. Next, 23.8 g of thionyl chloride was added dropwise with stirring. Further, 16 g of 4,4′-diaminodiphenyl ether slurried with 50 ml of γ-butyrolactone was added dropwise under ice cooling, stirred for 2 hours and then added dropwise to 10 l of ion-exchanged water while stirring, and the precipitate was filtered,
It was washed and air-dried to obtain a pale yellow powder. 10 g of this powder, 1.5 g of trimethylolpropane triacrylate, 0.6 g of Michler's ketone and 15 ml of n-methylpyrrolidone
In addition, a homogeneous solution was obtained. This solution is hereinafter referred to as S-1.

[0019]

[Reference Example 2] 110 g of diaminodiphenyl ether was added to N
-Dissolved in 278 g of methylpyrrolidone to give an amine solution. 120 g of pyromellitic acid anhydride was dispersed in 308 g of dimethylacetamide, and then 184 g of N-methylpyrrolidone was added and dissolved to obtain an acid solution. An acid solution was added to the amine solution at 60 ° C., and the mixture was reacted for 3 hours to obtain a uniform solution. 50 g of this solution, 1.15 g of Michler's ketone
Was dissolved in 30 g of dimethylacetamide, and a solution of 0.2 g of diethylaminoethyl methacrylate in 10 g of dimethylacetamide was mixed and filtered. This solution is hereinafter referred to as S-2.

[0020]

[Example 1] S using a spinner on a silicon wafer
-1 was applied and dried in a circulating oven at 70 ° C. for about 2 hours. The film thickness was 20 μm. 5-100 on this coating
A photomask on which a through-hole test pattern of μm square (in increments of 5 μm) is printed is brought into close contact, and M manufactured by Mikasa Co., Ltd.
It exposed for 30 seconds using the A-10 exposure machine. Next, spray development was carried out using a D spin 636 developing machine manufactured by Dainippon Screen Mfg. Co., Ltd. Development conditions are NMP / isopropyl alcohol / water (70/25/5, volume ratio)
Development was carried out for 30 seconds, followed by rinsing with ethyl lactate / isopropyl alcohol (80/20) rinse for 15 seconds. The resolution (minimum via hole diameter) of the obtained pattern was 20 μm, and a good pattern without any residue was obtained.

[0021]

[Comparative Example 1] S using a spinner on a silicon wafer
-1 was applied and dried in a circulating oven at 70 ° C. for about 2 hours. The film thickness was 20 μm. 5-100 on this coating
A photomask on which a through-hole test pattern of μm square (in increments of 5 μm) is printed is brought into close contact, and M manufactured by Mikasa Co., Ltd.
It exposed for 30 seconds using the A-10 exposure machine. Next, spray development was carried out using a D spin 636 developing machine manufactured by Dainippon Screen Mfg. Co., Ltd. Development conditions are NMP / isopropyl alcohol / water (70/25/5, volume ratio)
Development was carried out for 30 seconds, followed by rinsing with a xylene rinse for 15 seconds. The obtained pattern had a resolution (minimum via hole diameter) of 25 μm, and a small amount of residue was confirmed.

Examples 2 and 3 and Comparative Examples 2 and 3 are the results of experiments conducted using the same equipment as in Example 1 and Comparative Example 1 while changing the developing conditions. The experimental conditions are shown in Table-1.
Table 2 shows the composition of the developing / rinsing solution and Table 3 shows the experimental results.
Shown in.

[0023]

[Example 4] S using a spinner on a silicon wafer
-2 was applied and dried in a circulating oven at 60 ° C. for about 2.5 hours. The film thickness was 20 μm. 5 to 1 on this coating
A photomask on which a through-hole test pattern of 00 μm square (in 5 μm increments) is printed is brought into close contact with Mikasa Co., Ltd.
It exposed for 60 seconds using the MA-10 exposure machine made from. next,
Immersion development was carried out by putting a developing solution in a beaker. NMP
/ Lactic acid / water (70/25/5, volume ratio)
Immersion development was performed for 2 seconds, followed by immersion in a rinse solution of ethyl lactate for 15 seconds and air drying. The resolution (minimum via hole diameter) of the obtained pattern was 20 μm, and a good pattern without any residue was obtained.

[0024]

[Comparative Example 4] S using a spinner on a silicon wafer
-2 was applied and dried in a circulating oven at 60 ° C. for about 2.5 hours. The film thickness was 20 μm. 5 to 1 on this coating
A photomask on which a through-hole test pattern of 00 μm square (in 5 μm increments) is printed is brought into close contact with Mikasa Co., Ltd.
It exposed for 40 seconds using the MA-10 exposure machine made from. next,
Immersion development was carried out by putting a developing solution in a beaker. NMP
/ Isopropyl alcohol / water (70/25/5, volume ratio) for 60 seconds for immersion development, followed by immersing in n-butyl acetate rinse for 15 seconds and air drying. The resolution of the obtained pattern (minimum via hole diameter) is 25 μm.
And a small amount of residue was confirmed. Was given.

[0025]

[Table 1]

[0026]

[Table 2]

[0027]

[Table 3]

[0028]

According to the method of the present invention, when a pattern is formed using a photocrosslinking polymer composition, it is possible to provide a pattern having no residue and surface damage, which are problems in the past, and having an extremely high resolution. Became.

Claims (1)

[Claims] 1. A method of forming a predetermined pattern from a photosensitive composition containing a photocrosslinkable polymer having a repeating unit represented by the following formula [I] through an exposure step and a development step, which is not exposed to a developer. A pattern forming method, characterized in that after the portion is removed, it is washed with a rinse liquid containing 10% by volume or more of a compound represented by the following formula [II] which is liquid at room temperature. (X in the formula is a (2 + n) -valent carbocyclic or heterocyclic,
Y is a (2 + m) -valent carbon R is a group having a carbon-carbon double bond, W is a group capable of reacting with the carbonyl group of -COR by heat treatment to form a ring,
n is 1 or 2, m is 0, 1 or 2, and CO
R and Z are in an ortho position or a peri position. ) (R ₁ , R ₂ and R ₃ are H or an alkyl group having 1 to 8 carbon atoms.)