JPH0497254A - Photomask and its manufacturing method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Summary] Regarding photomasks and reticles used in the manufacture of semiconductor devices, and methods for manufacturing the same, the present invention provides photomasks and reticles that can be manufactured through simple manufacturing processes, and methods for manufacturing the same. [1] It is configured to include an acrylonitrile derivative polymer as a light-shielding material.

[2] A step of forming a thin film of an acrylonitrile derivative polymer on a transparent substrate, a step of selectively exposing the thin film of the acrylonitrile derivative polymer to radiation and then developing it to create a desired pattern; ￥Iil! ! and a step of imparting light-shielding properties to this by heating it.

[Industrial application field]

The present invention relates to photomasks and reticles (hereinafter referred to as photomasks) used in the manufacture of semiconductor devices, etc.
and its manufacturing method.

[Conventional technology]

A conventional photomask and its manufacturing method will be explained with reference to FIG. FIG. 2 is a diagram showing a conventional photomask manufacturing process. A conventional photomask consists of a transparent substrate made of quartz glass or the like and a patterned chromium thin film deposited on the surface of the transparent substrate, and is manufactured as follows. First, a thin chromium film is deposited on a transparent substrate by vapor deposition or sputtering. Next, a resist film is formed on the thin chromium film, and this resist film is selectively exposed to light using an electron beam lithography device, etc., and then developed. A resist pattern is provided. Next, the chromium thin film is etched using this resist pattern as an etching mask, and then the resist is removed to obtain a photomask having a desired pattern.

[Problem to be solved by the invention]

However, such a photomask has a problem in that the manufacturing process is complicated.

SUMMARY OF THE INVENTION An object of the present invention is to solve such problems and provide a photomask that can be manufactured by a simple manufacturing process and a method for manufacturing the same.

[Means for Solving the Problem] According to the present invention, the object is to provide a photomask characterized by: [1] containing an acrylonitrile derivative polymer as a light-shielding material; forming a thin film of an acrylonitrile derivative polymer on a substrate; selectively exposing the thin film of the acrylonitrile derivative polymer to radiation and developing it to create a desired pattern; and heating the thin film of the acrylonitrile derivative polymer. This can be achieved by providing a method for manufacturing a photomask characterized by including a step of imparting light-shielding properties to the photomask.

[Effect]

Acrylonitrile derivative polymers are sensitive to high energy radiation such as electron beams. Therefore, it itself has the same function as a photoresist.

Also, when it is heated, its absorbance to ultraviolet and far ultraviolet rays increases dramatically. This is presumed to be due to the generation of conjugated double bonds due to the following elimination reaction caused by heating.

(wherein,
The thin film is made opaque by heating to obtain a photomask.

〔Example〕

An embodiment of a photomask and a method for manufacturing the same based on the present invention will be described with reference to FIG. FIG. 1 is a diagram showing the manufacturing process of a photomask according to the present invention. First, azoisobutyronitrile as a polymerization initiator and N,N-dimethylformamide as a reaction solvent are added to α-chloroacrylonitrile, and radical polymerization is performed at 80°C. Next, this is purified by precipitation to obtain a polymer having a molecular weight of 800,000 and a degree of dispersion of 3. This polymer was mixed with 10% of N,N-dimethylformamide.
-t% solution and place it on a transparent substrate made of quartz glass for 1
Apply to a thickness of 5 μm (by spin code method).

This is heated (prebaked) in the open for 100°CCl2O minutes. This thin film is selectively exposed using an electron beam lithography device with an accelerating voltage of 20 v, and is developed with N,N dimethylformamide to obtain a negative pattern. Furthermore, using a hot plate, nitrogen gas was added at 500 SCCM, 2,
The temperature is raised to 400° C. in an Otorr p atmosphere. As a result, this polymer thin film becomes a light-shielding film with a thickness of 1.0 μm, and a photomask is obtained. The inventor created a reticle with a 3 μ-line and space pattern according to this method, measured the absorbance of the light shielding part for ultraviolet rays (g-line and i-line) and far ultraviolet rays, and found the results shown in the table on the next page. It was on the street. All of the absorbance values after heating are sufficient for use as a light shielding material for a photomask.

However, similar results were obtained.

It was also confirmed that the polymer light-shielding film thus obtained had a practical strength that could withstand brush cleaning.

The present invention is not limited to the above embodiments, but can be implemented with various modifications. For example, in the above examples, similar results were obtained when the temperature for the elimination reaction was raised to 300"C in the air.

Furthermore, even if a copolymer of α-chloroacrylonitrile and acrylonitrile is used as the acrylonitrile derivative polymer, or a copolymer of α-chloroacrylonitrile and methacrylonitrile is used (effects of the invention), the present invention According to the invention, it is possible to provide a photomask, a reticle, and a method for manufacturing the same that can be manufactured through a simple manufacturing process, which greatly contributes to streamlining the manufacturing of semiconductor devices.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a manufacturing process of a photomask according to the present invention, and FIG. 2 is a diagram showing a manufacturing process of a conventional photomask. Figure 1 showing the manufacturing process of the photomask of the present invention
Figure 2 Diagram showing the manufacturing process of a conventional photomask

Claims (1)

[Scope of Claims] [1] A photomask comprising an acrylonitrile derivative polymer as a light-shielding material. [2] A step of forming a thin film of an acrylonitrile derivative polymer on a transparent substrate; a step of selectively exposing the thin film of the acrylonitrile derivative polymer to radiation and then developing it to create a desired pattern; 1. A method for manufacturing a photomask, comprising the step of heating a thin film to impart light-shielding properties to the thin film.