JPH0480757A - Pattern forming method - Google Patents

Abstract

PURPOSE:To enable a fine line pattern having a rectangular cross section to be formed by using a photosensitive material made of an azido compound having a specified biphenyl skeleton and a phenol resin. CONSTITUTION:The photosensitive composition layer comprising the alkali- soluble phenol resin and the azido compound having a biphenyl skeleton represented by formula I formed on the substrate to be processed is exposed to the i-line of the bright lines of mercury through a photomask to transfer a pattern and developed with a aqueous alkaline solution. In formula I, each of R1 - R4 and R'1 - R'4 is, independently, H, OH, methyl, methoxy, azido, or halogen, thus permitting a fine negative pattern having a rectangular cross section to be formed by using the i-line reduction projection exposing device.

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a pattern forming method used in manufacturing solid-state devices that require fine wiring, such as semiconductor devices and magnetic bubble memories.

[Prior Art] As semiconductor devices become more highly integrated, demands for improved lithography technology are becoming increasingly severe, and efforts are being made to shorten the wavelength of exposure equipment, develop resist materials, and improve process technology. As a process technology, a phase shift exposure method that can form a finer pattern than the exposure wavelength of an exposure device is attracting attention. When this phase shift exposure method is combined with an i-line reduction exposure apparatus, it is possible to form a pattern finer than the exposure wavelength, and therefore, studies are underway in various places to apply it to device manufacturing. When applying phase shift exposure to device fabrication, a high-resolution negative resist is required due to restrictions on pattern shape. The i-line negative resists reported to date are:
For example, the azide-phenol resin resist described in Japanese Patent Application No. 57-146094, for example, Semiconductor Integrated Circuit Technology No. 3
Chemically amplified resists described in the 7th Lecture Proceedings P19, such as Procedures on SPIE (Proceedings, 5PIE), 6
31. It is classified as an image reversal resist described in plog. [Problems to be Solved by the Invention] Among the negative resists for i-rays mentioned above, chemically amplified resists and image reversal resists have high resolution, but they suffer from components that contribute to the insolubilization reaction (acids, amines, etc.). ) reacts with the substrate, so there is a problem that fine patterns cannot be formed depending on the type of substrate. On the other hand, azide-phenol resin resists have high resolution because they can be developed with alkaline aqueous solutions without swelling, and the phenol resin has high dry etching resistance, making them extremely useful for microfabrication in semiconductor manufacturing. It is known that However, in this negative resist, the exposure wavelength and the maximum absorption wavelength of azide almost match, and the light absorption at the exposure wavelength is large, making it difficult to expose the resist uniformly from the surface to the substrate surface. Therefore, there is a problem that the cross-sectional shape of the fine pattern formed becomes an inverted trapezoid. [Means for Solving the Problems] The problem with the prior art described above is that the azide compound (the following general formula) has a biphenyl skeleton that has low light absorption and photodecomposition with high efficiency at the exposure wavelength (i-ray). This problem can be solved by using a photosensitive composition made of a phenolic resin. (Here R11R21R31R41R1', R2'l
R3'tR4' may be the same or different and each represents a substituent selected from hydrogen, hydroxyl group, methyl group, methoxy group, azide group, and halogen. ) Examples of azide compounds that can be used in the present invention and which have high light absorption at the exposure wavelength (i-line) and photodecomposition with high efficiency include 4,4'-diazide-3,3'-dimethoxy. biphenyl, 4,4'diazide-3,3'-dimethylbiphenyl, 4,4'-diazide-2,2',5.
5'-tetrachlorobiphenyl, 4,4'-diazide-
3,3',5,5'-tetramethylbiphenyl, 3.
There are 3' and 4,4' tetraazido biphenyls, and two or more azide compounds can be used simultaneously. The amount of the azide compound is preferably in the range of about 5 to 40% by weight, and more preferably in the range of about 15 to 30% by weight, based on the phenol resin. Examples of the phenolic resin used in the present invention include 9, for example, poly(
4-vinylphenol), meta-para-cresol novolac resins, novolak resins, brominated poly(4-vinylphenol), and ortho-cresol novolac resins.

[Effect]

The azide compound having a biphenyl skeleton used in the present invention is efficiently photodecomposed by J-ray irradiation, and the generated nitrene efficiently insolubilizes the phenol resin, so that it acts as a highly sensitive negative resist. In addition, azide compounds with a biphenyl skeleton have low light absorption in the five-line (molecular extinction coefficient is 30001
/mol・cm or less), and when a resist using this azide compound as a photosensitizer (transmittance 70%/μm) is used, the cross section of the pattern due to light absorption is reduced like that of conventional azide resists (transmittance 1%/μm). No inverted trapezoidal shape was observed,
It is possible to form a fine pattern with a rectangular cross section. Furthermore, the phenol resin used in the present invention dissolves in an alkaline aqueous solution without swelling, and has excellent dry etching resistance, making it an optimal material as a polymer compound for forming fine patterns. Among phenolic resins, l
A resist using l+P-cresol novolak resin can have the largest difference in dissolution rate before and after exposure. From this, the phenolic resin used in the present invention is -111
+P-cresol novolak resin is optimal.

【Example】

Example 1 A resist solution was prepared by dissolving nl+P-cresol novolac resin and 4,4'-diazide-3,3'-dimethoxybiphenyl in ethyl cellosolve acetate at a weight ratio of 10=3. Next, the above resist solution was applied onto a substrate on which an antireflection film (BLOC2-16-40 manufactured by Hitachi Chemical Co., Ltd.) was formed on a silicon wafer, and baked at 80°C for 10 minutes to form a coating film with a thickness of 0.5 μm. The formed material was used as an exposed sample. This exposed sample was subjected to pattern exposure using a J-line reduction projection exposure apparatus. After exposure, the sample was immersed in a 2.38% aqueous tetramethylammonium hydroxide solution and developed. After development, the pattern was observed with an electron microscope, and it was confirmed that a 0.4 μm line and space pattern with a rectangular cross section was formed. Example 2 Instead of the azide compound used in Example 1, 4,4
Pattern formation was performed in the same manner as in Example 1 except that '-diazide-3,3'-dimethylbiphenyl was used, and a 0.4 μm line and space pattern was formed. Example 3 Instead of the azide compound used in Example 1, 4,
Pattern formation was performed in the same manner as in Example 1, except that 4'-diazide-2,2'5,5'-tetrachlorobiphenyl was used, and a 0.4 μm line &
A space pattern was formed. Example 4 Instead of the azide compound used in Example 1, 4,4
When pattern formation was performed in the same manner as in Example 1 except that '-diazide-3,3',5,5'-tetramethylbiphenyl was used, a 0.4 μm line and space pattern was formed. Ta.

【Effect of the invention】

According to the invention, Using an i-line reduction projection exposure system There,

Claims (1)

[Claims] 1. A step of forming a photosensitive composition layer containing an alkali-soluble phenol resin and an azide compound having a biphenyl skeleton represented by the following general formula on a substrate to be processed, the photosensitive composition layer A pattern forming method comprising the steps of: transferring the pattern by irradiating it with i-line, which is one of the bright lines of a mercury lamp, through a photomask; and developing the pattern using an alkaline aqueous solution after transferring the pattern. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (Here, R_1, R_2, R_3, R_4, R_1'
, R_2', R_3', and R_4' may be the same or different, and each represents a substituent selected from hydrogen, hydroxyl group, methyl group, methoxy group, azide group, and halogen. )