JPH01102567A - Manufacture of exposure mask - Google Patents

Abstract

PURPOSE:To obtain an exposure mask whose resolving power is high and which is inexpensive by using a photoresist brought to heat treatment as a light shielding film. CONSTITUTION:To a glass substrate 1, a photoresist 5 is applied and dried, and thereafter, by an exposure and a development by a mask, a desired photoresist pattern 5A is formed. Subsequently, to the photoresist 5A brought to patterning, a heat treatment is performed so as to allow it to have an optical characteristic for shielding a light beam of <=500nm wavelength being a photosensitive area of a general photoresist. In such a way, an exposure mask 5B having resolving power being equal to a metallic mask can be manufactured at a low cost.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to the structure and manufacturing method of an exposure mask used in photo Ringer fibrosis.

[Summary of the invention]

Exposure masks for microfabrication processes used in photolithography can be broadly classified into emulsion masks made of silver halide emulsions and metal masks made of metal or metal oxide films, each of which has advantages and disadvantages.

In other words, emulsion masks are generally inexpensive.

Resolution is low. Metal masks have high resolution.

It's expensive. Therefore, the high resolution of the metal mask is due to the resolution of the 7 photoresist, and this high resolution photoresist is heated.

The metal in the metal mask takes advantage of the fact that it rapidly changes color to dark red without deteriorating the film quality.

We have invented a high-resolution, inexpensive exposure mask made of photoresist that uses a heat-treated photoresist as a light-shielding layer, omitting metal oxide film formation and etching.

[Conventional technology]

2. Description of the Related Art Microfabrication processes using photolithography using exposure masks are used in the manufacturing process of electronic components, including semiconductor ICs.

The exposure masks used in this photolithographic microfabrication process can be broadly divided into two types: emulsion masks, which have silver halide emulsions coated on the surface of a glass substrate, and masks, which have metal or metal oxide films adhered to them. Two types of metal masks are used.

As shown in FIG. 8, the emulsion mask is made by placing a silver halide emulsion 2 on a glass substrate 1 in order to increase the optical density.
It is applied to a thickness of ~5 μm.

The emulsion 2 is patterned into a master mask pattern by N light, development, and fixing to form a desired pattern to produce an exposure mask.

In this emulsion exposure mask, the film thickness of the emulsion 2 is as thick as 3 to 5 μm, so the pattern width is limited to 2 to 3 μm. In addition, scratches and dirt on the emulsion surface, foreign matter in the emulsion, and pinholes cause pattern defects, which cannot be removed by cleaning, etc., and the lifespan of contact printers is short.

On the other hand, for the metal mask, as shown in FIGS. 9, 10, and 11, a metal 3° metal oxide 4 with a thickness of several hundred angstroms to several thousand angstroms is deposited on a glass substrate 1 by vapor deposition or sputtering. (Figure 9). A photoresist pattern 5A according to the desired pattern of the master mask is formed by photoringer fibrosis (FIG. 10).

Using this photoresist pattern 5A as an etching mask, a metal or metal oxide mask pattern 3A is formed by chemical etching using an etching solution, ion beam etching or plasma etching (FIG. 11). Compared to the emulsion mask, this metal mask allows patterning with a pattern width of 1 μm, has strong film strength, is highly durable, and is resistant to cleaning. Although it has advantages such as low defect density, metal
The drawbacks are that the substrate on which the metal oxide film is attached is expensive and the mask manufacturing process is complicated. It also includes a negative element, such as etching of metal and metal oxide films, which causes deviations in pattern dimensions.

[Problem that the invention seeks to solve]

The above-mentioned conventional techniques 9 For example, emulsion masks have drawbacks such as low resolution, weak film strength (mask wears out quickly, and high defect density).Metal masks, on the other hand, require a complex and expensive manufacturing process. In order to solve these drawbacks, the present invention aims to provide an exposure mask with high resolution and low defect density at low cost and through a simple process.

[Means for Solving the Problems] In order to achieve the above objects, the present invention provides a method for processing a metal, gold, or F4 oxide film into a mask pattern using a microfabrication process in the metal mask manufacturing process described above. The photoresist used in the IJ lithography process is an organic polymer compound that changes color to black, blackish brown, or dark red by heat treatment, and the spectral sensitivity range of the photoresist used in the IJ lithography process is below 500 rpm. It has optical properties that block light. Take advantage of the properties of this photoresist.

The formation of metal and metal oxide films and their etching in the metal mask described above are omitted, and a heat-treated photoresist film is used as the light-shielding pattern of the exposure mask.

FIG. 1 is a sectional view of an exposure mask according to the present invention.

In the figure, a heat-treated photoresist light shielding pattern 5B is formed on a glass substrate 1. As shown in FIG.

[Effect]

As a result, the high resolution of the metal mask is due to the photoresist, so the high resolution of the metal mask is retained, and the metal, metal oxide film formation, and metal that contribute to the high price of the metal mask are Etching of metal and metal oxide films, which causes dimensional deviation of the mask, can be omitted, and an exposure mask having the resolution of a metal mask can be manufactured at low cost using the same process as an emulsion mask. The heat-treated photoresist pattern changes color to black, blackish brown, or dark red, so metals, metal oxide films, etc.
It exhibits the same optical T properties and can be used as a light-shielding film for exposure masks.

〔Example〕

An embodiment of this invention is shown in FIGS. 2 and 3 below.

This will be explained with reference to FIG. 1 is a glass substrate, the material is soda lime glass, but if necessary, low expansion glass,
Alternatively, quartz glass can be used.

Further, if necessary, an antireflection film may be applied to the front surface or both the front and back surfaces.

5 is a photoresist, which is made of an alkali-soluble novolac resin using quinone azide as a photodegrading agent. 5A is a photoresist formed into a desired mask pattern by predetermined exposure and development processing. 5B is a patterned photoresist pattern with a wavelength of approximately 500 nm.
A photoresist pattern that has been heat-treated to block light at a distance of 1 meter or less.

If necessary, the glass substrate 1, which has been treated with an antireflection film on the front or both sides, is also treated with a photoresist adhesion reinforcement treatment 1, if necessary, with a treatment agent containing hexa7'methylenedisilazane as a main component. After processing, a photoresist 5 is applied (FIG. 2). After drying the photoresist, five desired photoresist patterns are formed by normal exposure and development using a master mask or submaster mask (FIG. 3). The patterned photoresist 5A is heat-treated so as to have optical properties that block light of wavelength 50 (lnm) or less, which is the photosensitive range of general photoresists.The heat treatment is typically performed for 2206060 minutes. The light-shielding properties of photoresists vary depending on the temperature, so depending on the purpose of use, temperatures below 220°C, e.g.
A usable exposure mask can be manufactured even by heat treatment at 0'C. In addition, in order to minimize the deformation of the photoresist pattern due to temperature, a 9-step heat treatment 1, for example 140
'C20 minutes → 160'C20 minutes → 180'C20 minutes → 2
It is best to do this continuously, such as 20 minutes at 00'C and 20 minutes at 220°C (Figure 4).

This photoresist exposure mask has the resolution of a metal mask with a pattern width of 1 μm, and can be easily manufactured by simply processing the photosensitive film of the emulsion mask.

In the first embodiment described above, a mask made of a heat-treated photoresist, for example, a photoresist made of an alkali-soluble novolak resin as a quinone azitra photodegrading agent, which significantly blocks light from the photoresist pattern by heat treatment, has low resistance to organic solvents, and the mask cannot be cleaned with organic solvents. Therefore, in the embodiment described in detail below, a photoresist pattern made of an alkali-soluble novolac resin as a quinone azide photodegradant is left in high-frequency sputtering after or before heat treatment. ``The photoresist pattern is made resistant to organic solvents by applying sputter damage.

The second embodiment of the present invention will be described below with reference to FIGS. 5, 6, and 7.
This will be explained using figures. 1 and 5A are the same as those shown in FIGS. 2 to 4. 5B' is a patterned photoresist pattern that has been heat-treated to have a light-shielding property against light having a wavelength of approximately 500 nm or less, and has also been subjected to sputter damage treatment.

Glass substrate 1 treated with 9 anti-reflection coating as necessary,
After surface treatment with a photoresist adhesion reinforcing treatment agent as required, photoresist 5 is applied (FIG. 5). After drying the photoresist, a desired photoresist pattern 5A is formed by normal exposure and development using a master mask or submaster mask (
Figure 6).

A photoresist pattern 5A patterned in the same manner as in the first embodiment is subjected to an auxiliary treatment so as to have an optical characteristic of blocking light having a wavelength of 500.1 m or less, which is the photosensitive region of a general photoresist.

The appropriate heat treatment is typically 220'C for 60 minutes. The light-shielding property of a photoresist changes depending on the temperature of the heat treatment, so depending on the purpose of use, it is possible to produce an exposure mask that can be used satisfactorily even with heat treatment at temperatures below 220'C, such as 200'C and 180'C'. In addition, to minimize deformation of the photoresist pattern due to heat treatment, one-step heat treatment 9, for example, 140°C 20 minutes → 160°C 20 minutes -> 180°C 20 minutes → 200°C
It is best to do this continuously for 20 minutes → 220°C2o minutes. The heat-treated photoresist pattern is further sputter-damaged by high-frequency sputtering to form an organic solvent-resistant light-shielding photoresist pattern 5B'.
shall be. Sputter damage is 2. For example, sputtering output is 0.7 W/i.

A sputtering time of 30 minutes is appropriate, but the sputtering output and sputtering time can be appropriately selected depending on the purpose of use (FIG. 7). .

[Fruits and vegetables of invention]

According to the present invention, by imparting light-shielding properties to a photoresist for microfabrication simply by subjecting it to heat treatment, an exposure mask that has the same resolution as a metal mask can be created using a metal film or a metal oxide film of the metal mask. By omitting film formation, it can be made cheaper than a metal mask. Furthermore, in a photoresist exposure mask, the photoresist pattern itself becomes a light-shielding film, which causes dimensional deviation in the metal mask. Etching of metal films and metal oxide films can also be omitted, making it easy to obtain patterns faithful to design dimensions.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a photoresist exposure mask of the present invention, FIG. 8g2, FIG. 3, FIG. 4, and FIG. 5. 6 and 7 are process diagrams for manufacturing a photoresist exposure mask showing an embodiment of the present invention, and FIG. 8 is a sectional view of a conventional silver halide emulsion exposure mask. FIG. 9, FIG. 10, and FIG. 11 are process diagrams for manufacturing a conventional exposure mask made of metal or metal oxide. 1 glass substrate, 5: photoresist, 5A: photoresist pattern, 5B, 5B': light-shielding photoresist pattern.

Claims (1)

[Scope of Claims] 1. In an exposure mask used for microfabrication consisting of a light-shielding film that blocks light necessary for exposing a transparent substrate and a photoresist film, a pattern for microfabrication is formed on a photoresist for microfabrication. Later, heat treatment is applied to add light-shielding properties, and the photoresist for microfabrication itself becomes a light-shielding film.
A method for manufacturing an exposure mask characterized by comprising a transparent substrate and a photoresist light-shielding film. 2. In the exposure mask used for microfabrication, which consists of a light shielding film that blocks the light necessary to expose the transparent substrate and photoresist film, sputter damage is applied to the photoresist for microfabrication after forming the pattern for microfabrication. A method for producing an exposure mask characterized by adding light-shielding properties and organic solvent insolubility, thereby making the photoresist for microfabrication itself a light-shielding pattern. 3. In an exposure mask used for microfabrication consisting of a light-shielding film that blocks light necessary to expose a transparent substrate and a photosensitive film, a pattern for microfabrication is formed on a photoresist for microfabrication, and the microfabrication pattern is formed by heat treatment. A method for manufacturing an exposure mask, characterized in that the photoresist pattern for microfabrication itself is made into a light-shielding pattern by imparting light-shielding properties to a photoresist pattern for microfabrication, and then adding organic solvent insolubility by applying sputter damage. 4. Sputter damage is applied to the photoresist for microfabrication after forming the microfabrication pattern in the exposure mask used for microfabrication, which consists of a light shielding film that blocks the light necessary to expose the transparent substrate and photoresist film. A method for manufacturing an exposure mask, characterized in that the photoresist for microfabrication itself is used as a light-shielding pattern, by adding light-shielding properties and organic solvent insolubility, and then heat-processing the photoresist pattern to complete the light-shielding properties.