JPS6129493B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a novel resist material, and more particularly to a method for producing a resist material that is easily polymerized and insolubilized by radiation having a wavelength of 2000 Å or less, such as electron beams, X-rays, and vacuum ultraviolet rays.
In recent years, with the increasing integration of semiconductor integrated circuits and the production of ultrafine-structured sonic elements, magnetic valve memories, etc., the application of lithography using short-wavelength radiation such as electron beams, X-rays, and vacuum ultraviolet rays has become popular. is being considered. Compounds that are polymerized and insolubilized by radiation as described above are well known in the art as negative resist materials. Negative resist materials are typically dissolved in a suitable organic solvent, applied to the surface of the workpiece, and then the solvent is evaporated to form a resist film on the surface, which is then irradiated with radiation to harden the irradiated area. . Then,
The unirradiated areas are removed with a solvent to form a resist image, and the areas not covered with the cured film are processed by etching, impurity doping, etc., and then the cured film is removed by chemical methods or plasma etching. . Some of the known negative-tone plastics are known to have sufficiently high sensitivity for practical use, but in general, the higher the sensitivity of negative-tone resist materials, the worse their resolution and stability. However, a truly practical negative resist material that satisfies all of sensitivity, resolution, and stability has not yet been known. The inventors of the present invention have conducted extensive research in view of the current situation, and as a result have come up with a method for producing a resist material that has truly practical performance. That is, the present invention can be applied to wavelengths such as electron beams, X-rays, and vacuum ultraviolet rays.
The present invention provides a method for producing a negative resist material that is highly sensitive to radiation of 2000 Å or less and has excellent resolution and stability. The manufacturing method of the resist material of the present invention requires two
The method is characterized in that a compound having 1 or more epoxy groups is first reacted with a monobasic unsaturated fatty acid, and then reacted with hydrogen halide until the remaining epoxy groups are substantially eliminated. The present invention will be explained in detail below. Generally, the method of introducing unsaturated groups into the side chains of polymers is well known as a method for producing negative resist materials. One useful reaction method for introducing unsaturated groups into a polymer is to react a polymer having an epoxy group with an unsaturated fatty acid. However, when a resist material is actually produced using this method, the stability of the material is poor, and in some cases, the resist material gels during isolation from the reaction system or is stored as a resist solution. It turns out that the body undergoes alteration while it is there. Even those with relatively good stability may cause fogging during the pre-baking process, produce scum or granular residue after development, or produce whiskers, resulting in poor resolution and cannot be used for practical purposes. It wasn't. The above-mentioned scum refers to amorphous lump-like deposits that remain in unirradiated areas, and whiskers refer to development residues that protrude in the shape of icicles or whiskers from the boundaries of irradiated areas to unirradiated areas. The residue causes a significant deterioration in resolution. However, as a result of further investigation, we found that after reacting the raw epoxy compound with a monobasic unsaturated fatty acid, the stability of the reactant could be improved if the reactant was not taken out immediately but was brought into contact with hydrogen halide before being separated. It has become clear that an excellent resist material can be obtained. The present invention is based on such knowledge. Hydrogen halides react quantitatively with epoxy groups under mild conditions. As mentioned above, the resist material obtained by treatment with hydrogen halide has extremely good stability and excellent resolution, and provides a sharp resist pattern without development residue or whiskers. It is well known that epoxy groups themselves undergo crosslinking reactions when exposed to radiation such as electron beams and X-rays, but the resist materials produced by the method of the present invention are ,
The sensitivity to radiation with a wavelength of 2000 Å or less, such as electron beams, X-rays, and vacuum ultraviolet rays, has been improved by more than 5 to 10 times, and as mentioned above, it has excellent resolution and stability, which are the lifeblood of resist materials for microfabrication. ing. The compound having two or more epoxy groups in one molecule used in the present invention only needs to be soluble,
Glycidyl esters and epoxidized polyolefins are used, but generally, homopolymers of vinyl monomers having glycidyl groups or copolymers with other vinyl monomers are used, such as polyglycidyl methacrylate, polyglycidyl acrylate, Copolymers of glycidyl methacrylate and ethyl acrylate, copolymers of glycidyl acrylate and styrene, and poly(p-vinylbenzoic acid glycidyl ester) can be advantageously used. However, it is not limited to these. On the other hand, the unsaturated fatty acids used in the present invention must be monobasic. Examples of such are maleic acid monoester, fumaric acid monoester, itaconic acid monoester, acrylic acid,
Methacrylic acid, cis-4-cyclohexene-1,
Examples include 2-dicarboxylic acid monoester, 5-norbornene-2,2-dicarboxylic acid monoester, hexachloro-[2,2,1]-bicyclohept-5-ene-2,3-dicarboxylic acid monoester, It is not limited to these. Next, these unsaturated fatty acids and the above-mentioned epoxy compound are brought into contact with each other directly or in a solvent and simply heated, or more preferably with a catalyst such as a tertiary amine such as triethylamine or a quaternary ammonium salt such as trimethylbenzylammonium chloride. The reaction can be caused by gentle heating in the presence of For example, in the presence of a tertiary amine catalyst, 60 to 120
The purpose can be achieved with a reaction time of 1 to 10 hours at ℃. Furthermore, by selecting the reaction conditions at this stage, the rate of introduction of unsaturated fatty acids can be changed to adjust the sensitivity of the resist material that is the final product. The reaction solvent must be non-reactive with epoxy groups and must be a good solvent for the raw materials and products.
For example, esters such as methyl cellosolve acetate and ethyl acetate, acetone, ketones such as methyl isobutyl ketone, ethers such as dioxane and tetrahydrofuran, and aprotic polar solvents such as dimethylformamide are advantageously used as reaction solvents. . These reaction solvents may be used alone or in combination. The optimal reaction solvent is selected depending on the type of reactants and reaction conditions. Next, the hydrogen halides used in the present invention are hydrogen chloride, hydrogen bromide, hydrogen fluoride, and hydrogen iodide, and these can be used alone or as alcohols, ethers, ketones, esters, and aprotic It is used by dissolving it in an organic solvent such as a polar solvent or in water. These are added to the reaction system after the above-mentioned reaction between the fatty acid and the epoxy compound, and the reaction is allowed to occur while being maintained at an appropriate reaction temperature. For example, when hydrochloric acid is used, hydrogen chloride can be quantitatively added to the remaining epoxy groups by reacting at room temperature to 50°C for about 1 hour. After completion of the reaction, the target product, ie, the resist material, can be separated as a powder or bulk solid by pouring the reaction mixture into a non-solvent such as alcohol, water, n-hexane. Excess hydrogen halide can be removed by washing the resist material with water or alcohol. The resist material thus obtained is preferably dried at a temperature not exceeding 80°C. The dried resist material is used after being dissolved in a suitable solvent; in this case, the solvent may be the same as the reaction solvent described above, or may be a solvent containing active hydrogen such as methyl cellulose. Mixtures of solvents are also useful. The type of solvent is selected depending on the resist material and usage conditions. Next, the present invention will be explained in more detail with reference to Examples. Example 1 Polyglycidyl methacrylate (number average molecular weight
20000, epoxy value 660m mol/100g) and 62.4g of monomethyl maleate were dissolved in 500cc of dioxane, 2.0cc of triethylamine was added thereto, and the mixture was kept at 101-102°C and stirred for 2 hours. Next, the reaction temperature was lowered to 30-35°C, and dilute hydrochloric acid (45 c.c. of 35% hydrochloric acid, 100 c.c. of water) was added and stirred. After 1 hour, the reaction mixture was poured into water from step 5 to recover the precipitated polymer, which was pulverized with a mixer, washed with water until no chloride ions were observed, and then dried under reduced pressure at 50°C. The yield was 58.0g. The obtained product has an epoxy value
At 4.3 mmol/100 g, substantially all the epoxy groups had reacted and disappeared. This resist material was dissolved in methyl cellosolve acetate (MCA), spin-coated onto a silicon substrate with an oxide film, and prebaked at 80°C for 30 minutes to form a thin film with a thickness of 5000 Å. This thin film was irradiated with an electron beam at an acceleration voltage of 27 KV in a vacuum, and then developed by immersing it in MCA at 35° C. for 30 seconds, followed by rinsing with n-butyl acetate. Minimum amount of charge remaining on resist film after development (D ⁱ _g ), amount of charge remaining on 50% of coated film thickness (D ^0.5 _g ), contrast

[Formula] is shown below in comparison with the raw material polyglycidyl methacrylate (PGMA). The meaning of these numbers can be found in the literature (LFThompson;
SOLID STATE TECHNOLOGY. July issue, 1974, p. 27).

[Table] In addition, the resist material thin film created as described above was swept with a finely focused electron beam with an acceleration voltage of 27 KV and a spot diameter of 200 Å, and developed in the same manner as described above.
A resist line with a width of 2500 Å and a thickness of 5000 Å was obtained. It cut well and no hair development residue was observed. This resist material thin film did not cause thermal fogging even after prebaking at 100°C for 30 minutes. Also,
The MCA solution of resist material stored in an amber bottle at room temperature did not change in quality or change in performance after one year. Example 2 Polyglycidyl methacrylate (number average molecular weight
20000, epoxy value 660m mol/100g) 2.8g and monomethyl fumarate 2.6g were dissolved in 50cc of dioxane, and triethylamine 0.5cc was added to 101
It was kept at ~102°C and stirred for 2 hours. After cooling, dimethylformamide solution of hydrochloric acid (3 c.c. of 35% concentrated hydrochloric acid,
20 c.c. of dimethylformamide was added and stirred while maintaining the temperature at 30-35°C. After 1 hour, the reaction mixture was poured into 1 water to separate and collect the polymer, pulverized with a mixer, washed with water until chlorine ions disappeared, and then heated at 50°C.
It was dried. (Yield 2.0g, epoxy value 2.0m
mol/100g) This polymer (resist material) is dissolved in dioxane and spin-coated onto a substrate on which metallic chromium has been deposited.
A thin film with a thickness of 2700 Å was formed by prebaking at 60°C for 30 minutes. This resist material thin film was irradiated with an electron beam at an acceleration voltage of 27 KV in a vacuum, developed by immersing it in ethyl acetate at 35° C. for 30 seconds, and rinsing with n-butyl acetate. The sensitivity and contrast of this resist material were as follows.

[Table] Furthermore, this resist material exhibited resolution and stability comparable to those of the resist material shown in Example 1. Example 3 Polyglycidimethacrylate (number average molecular weight
20000, epoxy value 660m mol/100g) 2.8g, p
-Methoxyphenol 0.1g, methacrylic acid 2.0g
was dissolved in 50 c.c. of dioxane, 0.5 cc of triethylamine was added thereto, kept at 101-102°C, and stirred for 2 hours. After cooling, a solution of hydrochloric acid in dimethylformamide (3 c.c. of hydrochloric acid, 30 c.c. of dimethylformamide) was added and stirred at 30 to 35°C. After 1 hour, the reaction mixture was poured into water from step 1 to recover the precipitated polymer, which was washed with water while being pulverized with a mixer until no chloride ions were present. This was dried under reduced pressure at 30°C to obtain 1.6 g of resist material. Epoxy value is measured value 0.0m mol/
At 100g, it was practically zero. This resist material was dissolved in dioxane, spin-coated onto a silicon substrate with an oxide film, and prebaked at 60°C for 15 minutes to form a thin film with a thickness of 2700 Å. This thin film was irradiated with an electron beam at an accelerating voltage of 27 KV in a vacuum, developed by immersing it in MCA at 35° C. for 30 seconds, and rinsed with n-butyl acetate. The sensitivity and contrast of this resist material were as follows.

[Table] Example 4 Poly(p-vinylbenzoic acid glycidyl ester) according to literature* was synthesized. The viscosity [η] was 100 (30°C, dimethylformamide solution), and the epoxy value was 420 mmol/100g. *Y.Iwakura.etal.Bull.Chem.Soc.Japan.41.186−
191 (1968) 2.0 g of this polymer and 2.6 g of monomethyl maleate
was dissolved in 50 c.c. of dioxane, 0.5 cc of triethylamine was added thereto, kept at 101-102°C, and stirred for 2 hours. After cooling, a solution of hydrochloric acid in dimethylformamide (3 c.c. of 35% concentrated hydrochloric acid, dimethylformamide) was added. 30
cc) was added and stirred while maintaining the temperature at 30-35℃. After 1 hour, the reaction mixture was poured into water from step 1 to separate and recover the polymer, which was washed with water while being crushed with a mixer until no chloride ions were observed, and then dried under reduced pressure at 50°C. (Yield 2.1g Epoxy value 3.2m
mol/100g) This polymer (resist material) was dissolved in MCA (methyl cellosolve acetate), spin-coated onto a silicon substrate with an oxide film, and prebaked at 80°C for 30 minutes to form a thin film with a thickness of 5000 Å. This thin film was irradiated with an electron beam at an accelerating voltage of 27 KV in a vacuum, developed with MCA at 35°C, and rinsed with isoaluminium acetate. The sensitivity and contrast of this resist material are as follows.

[Table] Glycidyl ester)
Using this resist material, a resist pattern with a Ryan and space of 0.5 μm was easily obtained. Stability was comparable to the resist material of Example 1. Example 5 A resist material was produced in the same manner as in Example 1. This material was spin-coated onto a chromium-deposited glass substrate and pre-baked at 80℃ for 30 minutes to a thickness of 5000Å.
A thin polymer film was created. This thin film was irradiated with soft X-rays (MoL rays 5.4 Å). Irradiation energy was measured using a gas flow type proportional counter. For resolution, a silicon membrane mask with a gold pattern was used, and a space of 15,000 Å was maintained between the mask and the polymer thin film. After X-ray irradiation, the substrate was developed by immersing it in MCA at 35° C. for 30 seconds, and was rinsed with n-butyl acetate. The irradiation dose (D ^0.5 g) required to leave 50% (2500 Å) of the coating film thickness after development is 40 mJ/cm ² and 8000 Å
We were able to faithfully reproduce the gold lattice pattern.

Claims (1)

[Claims] 1. A compound having two or more epoxy groups in one molecule is first reacted with a monobasic unsaturated fatty acid, and then reacted with hydrogen halide until the remaining epoxy groups are substantially eliminated. A method for producing resist materials that become insolubilized by radiation.