JPH07209879A - Forming method of pattern - Google Patents

Abstract

PURPOSE:To improve the resolution without decreasing the throughput by using two or more kinds of developers having different solubilities with photocrosslinked polymer in the order of higher solubility. CONSTITUTION:A pattern is formed in a photosensitive compsn. containing photocrosslinking polymer having a repeating unit expressed by the formula by a spray or paddle developing method in an automatic machine. Two or more kinds of developers having different solubilities with the photocrosslinking polymer are used in the order of higher solubility. As for the photocrosslinking polymer expressed by the formula, a polyimide precursor having photosensitive groups in the side chains of the repeating unit is used for example, produced by polycondensation of acid anhydride such as pyromellitic anhydride and benzophenone tetracarboxylic anhydride and diamine such as 4,4'- diaminediphenylether and 4,4-diaminediphenylsulfone.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for forming a pattern with high resolution from a photosensitive composition containing a photocrosslinkable polymer used as a polyimide precursor when forming an interlayer insulating film in the semiconductor industry. It is about.

[0002]

2. Description of the Related Art In recent years, in the semiconductor industry, a resin having a heterocycle such as a polyimide resin, which has high heat resistance and is excellent in forming a step as compared with an inorganic substance, is used as an insulating film or a passivation film in a solid-state element or in an integrated circuit It has also come to be used as an interlayer insulating film for wiring boards for multilayer printing. 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, a photosensitive composition containing a photo-crosslinkable polymer having a repeating unit represented by the following formula [I] can form a pattern even when it is a thick film. It is possible and has an excellent feature that there is almost no film slippage in the exposed portion during development.

[0004]

[Chemical 2]

The pattern forming method using the composition is carried out, for example, in the following order of steps. 1 Application: The precursor composition varnish is applied 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 the unexposed area is rinsed with a rinse solution which is a poor solvent. 5 Thermosetting: By heating, it is converted into a polyimide resin to obtain a predetermined pattern.

In a series of steps, as a conventional developing / rinsing solution, a developing solution of a good solvent of the precursor alone 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 the poor solvents are used. Is used. For example, a developing solution containing N-methylpyrrolidone or γ-butyrolactone alone, a developing solution containing a mixture thereof with xylene or isopropyl alcohol, or a rinse solution containing isopropyl alcohol or xylene alone or a mixture thereof is used. As the developing method, a spray developing method, a paddle developing method, a dip developing method or an ultrasonic developing method is used.

[0007]

In the case of forming a pattern by the above-mentioned method, as a developing solution, the mixing ratio of the poor solvent is increased in the range in which the developing solution dissolves the photocrosslinkable polymerization composition, and the dissolution time is increased. A longer pattern can obtain a pattern with higher resolution. Further, as a developing method, a spray developing method and a paddle developing method are methods that can maximize the uniformity of pattern quality such as resolution, and are most commonly used as an automatic apparatus.

On the other hand, when such a general apparatus is used, it is structured so that each substrate is processed one by one. Therefore, unless the processing time for each substrate is limited, the developing process is It significantly reduces the throughput. However, for that purpose, the proportion of a good solvent as a component of the developer must be increased to some extent to accelerate the dissolution rate of the photocrosslinkable polymer composition, which makes it difficult to obtain high resolution.

[0009]

As a result of earnest studies for solving the problems of the prior art as described above, the present inventors have found that the throughput can be improved by using the developing method described in detail below. It was possible to obtain a pattern with high resolution without degrading. That is, the present invention provides the following formula [I]
In the method for forming a pattern from a photosensitive composition containing a photocrosslinkable polymer having a repeating unit, the solubility in the photocrosslinkable polymer when developing by a spray or paddle development method using an automatic machine. The method for forming a pattern is characterized in that two or more kinds of developing solutions having different levels are used in the order of high solubility.

[0010]

[Chemical 3]

The X of the formula [I] used in the present invention is a chemical structure excluding the carboxyl group of aromatic tetracarboxylic acid, and the Y is excluding the amino group of aromatic diamine. It shows a chemical structure. Examples of the photocrosslinkable polymer of the formula [I] include acid anhydrides such as pyromellitic acid anhydride and benzophenone tetracarboxylic acid anhydride, and, for example, 4,4′-diaminodiphenyl ether and 4,4′-diaminodiphenyl sulfone. Polyimide precursors having a photosensitive group on the side chain of a repeating unit formed by polycondensation with a diamine such as

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, 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 photosensitive compound mixed for the purpose of improving the photosensitivity of the photocrosslinkable polymer having the repeating unit represented by the formula [I] include the following. For example, benzophenones such as benzophenone and 4,4′-bis (dimethylamino) benzophenone, benzoin ethers, anthraquinones, thioxanthone derivatives, 2,6-bis-
Bisazides such as (4'-diethylaminobenzal) -cyclohexanone, mercapto compounds such as 1-phenyl-5-mercaptotetrazole, 1-phenyl-1,2
-Propanedion-2- (O-ethoxycarbonyl)-
Examples include oximes such as oximes and imidazoles such as 2,4,5-triphenylimidazole dimers. The following are preferable examples of the photosensitive monomer. For example, (meth) acrylates such as trimethylolpropane triacrylate, trimethylolpropane trimethacrylate and dimethylaminoethylmethacrylate, mercapto compounds such as thioglycol, maleimides such as phenylsulfonylmaleimide, and isocyanates such as ethylmethacrylate methacrylate. is there. It is preferable to add 0.1 to 50 parts by weight of these additives to 100 parts by weight of the photocrosslinkable polymer. As the solvent, N, N'-dimethylformamide,
N, N'-dimethylacetamide, γ-butyrolactone, N-methylpyrrolidone and the like are preferable.

As the developing solution, a good solvent such as N, N'-dimethylformamide, N, N'-dimethylacetamide, γ-butyrolactone, N-methylpyrrolidone, diglyme or cyclopentanone alone, water, xylene, ethanol or the like can be used. Alcohols such as isopropyl alcohol,
A substance having a dissolution rate adjusted by mixing a poor solvent such as cellosolves such as methyl cellosolve is used. For example, when two types are used, the type of good solvent is not particularly limited as long as it dissolves the photocrosslinkable polymerization composition,
From the viewpoint of solubility, if the developing solutions are the developing solutions 1, 2, 3, ... In descending order of solubility, the good solvent for the developing solution 1 is γ.
-Butyrolactone, N-methylpyrrolidone, diglyme, cyclopentanone alone and a mixture of these with a poor solvent are preferable, and as the developer 2 etc., diglyme, cyclopentanone, cyclohexanone alone and these A mixed solution with a poor solvent is preferred.

The developing solutions 1 and 2 are preferably selected such that the dissolution rate ratio of the photosensitive composition containing the photocrosslinkable polymer is 2 or more from the viewpoint of resolution, and further 5
The above is preferable. However, the sum of the developing times of the developing solutions 1 and 2 is preferably within 2 minutes from the viewpoint of throughput, and more preferably within 1 minute. Also, developer 1
If the dissolution rate is too high, the pattern will collapse and the effect will be lost. Therefore, the dissolution rate is preferably 2 μm or less per second in the coating film after drying the unexposed portion. The compositions of the developers 1, 2 and the like are selected so as to satisfy these requirements. Furthermore, the composition must not leave a residue after the rinse.

As a coating method on the substrate, a spinner, a roll coater or the like is representative, and examples of the substrate include a silicon wafer, ceramics, a copper plate and the like. 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. The drying time varies depending on the thickness and the drying method, but is preferably about 1 to 5 minutes 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 if the treatment such as the heat treatment after the exposure is carried out according to the performance of the varnish used.

The pattern image of the developed photosensitive composition is immediately washed with a rinse liquid to remove the developer. As the rinse liquid, it is preferable to use a poor solvent for the photosensitive composition, and examples thereof include toluene, xylene, acetone, ethylbenzene, methylcellosolve, ethyl acetate, isopropylbenzene, isopropyl alcohol, isobutyl alcohol, and water. .

The conversion of the obtained polyimide precursor pattern into polyimide is carried out by thermosetting at 200 ° C. to 500 ° C. for 5 minutes to 3 hours. Examples of the method include a circulation oven, a vertical thermosetting oven, and a hot blade.

[0019]

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

[0020]

Synthesis 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 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 g of trimethylolpropane triacrylate, 0.4 g of Michler's ketone, 1-phenyl-1,2-propanedione-2- (O-ethoxycarbonyl) -oxime.
4 g was added to 20 ml of N-methylpyrrolidone to obtain a uniform solution. This solution is hereinafter referred to as S-1.

[0021]

[Synthesis 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.

[0022]

[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. 10-50 on this coating
A photomask on which a through-hole test pattern of square (2 μm increments) was printed was brought into close contact and exposed for 60 seconds using a PLA-601 exposure machine manufactured by Canon Inc. next,
Spray development was carried out using a D-SPIN636 developing machine manufactured by Dainippon Screen Mfg. Co., Ltd. Development conditions are N
MP / xylene (50/50, volume ratio) 2 with developer 1
Develop for 0 seconds, then cyclopentanone / xylene (4
The developing solution 2 (0/50, volume ratio) was developed for 20 seconds, and rinsed with a rinse solution of isopropyl alcohol for 15 seconds. Resolution of the obtained pattern (minimum via hole diameter)
Was 20 μm, and a good pattern without any residue was obtained.

[0023]

Examples 2 to 5 Examples 2, 3, 4, and 5 are the results of experiments conducted by using the same equipment as in Example 1 but changing the developing solution. Table 1 shows these experimental conditions, and Table 2 shows the results of the developing solutions 1 and 2 and the respective developing times and resolutions.

[0024]

[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. 10-50 on this coating
A photomask on which a through-hole test pattern of square (2 μm increments) was printed was brought into close contact and exposed for 60 seconds using a PLA-601 exposure machine manufactured by Canon Inc. next,
Spray development was carried out using a D-SPIN636 developing machine manufactured by Dainippon Screen Mfg. Co., Ltd. Development conditions are N
26 with MP / xylene (50/50, volume ratio) developer
Second development, followed by rinsing with isopropyl alcohol for 15 seconds. The resolution of the obtained pattern (minimum via hole diameter) was 26 μm, and a small amount of residue was confirmed.

[0025]

Comparative Examples 2 and 3 Comparative Examples 2 and 3 are the results of experiments using the same equipment as in Comparative Example 1 but changing the developing solution. The experimental conditions are shown in Table 1, and the results of the developer composition, developing time and resolution are shown in Table 3.

[0026]

[Sixth Embodiment] S was formed on a silicon wafer by using a spinner.
-2 was applied and dried in a circulating oven at 60 ° C. for about 2.5 hours. The film thickness was 20 μm. 10 to this coating
A photomask on which a through-hole test pattern of 50 μm square (in steps of 2 μm) was printed was brought into close contact, and exposed for 70 seconds using a PLA-601 exposure machine manufactured by Canon Inc. Next, D-SPIN manufactured by Dainippon Screen Mfg. Co., Ltd.
Paddle development was carried out using a 636 developing machine. The developing conditions are as follows: NMP / xylene (50/50, capacity ratio) developer 1 is discharged for 10 seconds, rotation development is performed at a rotation speed of 10 rpm for 80 seconds, and then diglyme is used as developer 2 and discharged for 10 seconds, and then rotated at 10 rpm for 20 seconds. Development was carried out, followed by rinsing with isopropyl alcohol for 15 seconds. The resolution of the obtained pattern (minimum via hole diameter) was 26 μm, and a small amount of residue was confirmed.

[0027]

[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. 10 to this coating
A photomask on which a through-hole test pattern of 50 μm square (in steps of 2 μm) was printed was brought into close contact, and exposed for 70 seconds using a PLA-601 exposure machine manufactured by Canon Inc. Next, D-SPIN manufactured by Dainippon Screen Mfg. Co., Ltd.
Paddle development was carried out using a 636 developing machine. The developing conditions were as follows. A developing solution of NMP / xylene (50/50, volume ratio) was discharged for 10 seconds, rotational development was performed at a rotation speed of 10 rpm for 100 seconds, and then isopropyl alcohol was rinsed for 15 seconds. The resolution of the obtained pattern (minimum via hole diameter) was 30 μm, and a small amount of residue was confirmed.

[0028]

[Table 1]

[0029]

[Table 2]

[0030]

[Table 3]

[0031]

According to the method of the present invention, it is possible to improve the resolution without deteriorating the throughput by performing pattern formation using the photocrosslinking polymer composition.

Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location H01L 21/312 B 7352-4M

Claims (1)

[Claims] 1. A method for forming a predetermined pattern from a photosensitive composition containing a photocrosslinkable polymer having a repeating unit represented by the following formula [I], which is developed by spraying or paddle developing using an automatic machine. When performing, the pattern forming method, characterized in that two or more kinds of developers having different solubilities with respect to the photocrosslinkable polymer are used in the order of high solubility. [Chemical 1]