JPH0373950A - Manufacture of mask for exposing - Google Patents

Abstract

PURPOSE:To prevent the strains of mask patterns and to easily from a mask by providing a stage for partially etching away a substrate with a supporting frame as the mask and offsetting a 2nd stress appearing along an underlying film after the etching by a 1st stress. CONSTITUTION:The substrate 9 of the regions through which X rays are trans mitted is removed by etching method using a prescribed liquid mixture with the supporting frame 12 as the mask. The substrate 9 loses its support at this time and the supporting frame 12 tends to shrink so that about 1X10<9>dyne/cm<2> compressive stress appears along the surface of the underlying film 10. Since about 1X10<9>dyne/cm<2> tensile stress is previously imparted along the surface of the underlying film 10, these stresses are offset by each other. The elongation and contraction of the pattern forming film 11 are obviated in such a manner and, therefore, the patterns 11a formed by patterning the pattern forming film 11 is not strained. Thus, the strain of the mask patterns is prevented and the mask is easily formed.

Description

[Detailed Description of the Invention] [Summary] Regarding the method of manufacturing a mask for exposure, in more detail,
Regarding the manufacturing method of a 6n light mask used when transferring a pattern, especially when transferring a pattern by X-ray irradiation, distortion of the mask pattern due to stress generated when creating the exposure mask can be prevented. The purpose of the present invention is to provide a method for creating an exposure mask that can easily create such a mask, and includes a step of forming a base film on one surface of a substrate, and a step of forming a first layer along the surface of the base film in advance. forming a pattern-forming film on the base film so as to generate stress; patterning the pattern-forming film; attaching a support frame to the periphery of the other surface of the substrate; The method includes the steps of partially etching and removing the substrate using the support frame as a mask, and canceling out a second stress appearing along the base film after etching with the first stress.

[Industrial application field]

The present invention relates to a method of manufacturing an exposure mask, and more specifically, to a method of manufacturing an exposure mask used when transferring a pattern, particularly when transferring a pattern by XLA irradiation.

2. Description of the Related Art As patterns become finer, a pattern transfer method using X-ray irradiation is used for patterning semiconductor devices.

There is also a demand for a highly accurate exposure mask with a pattern drawn thereon.

[Conventional technology]

FIGS. 4(a) to 4(f) are cross-sectional views illustrating a conventional method of creating an exposure mask used in pattern transfer by X-ray irradiation.

First, a base film 2 made of SiC is formed on the base vil made of St shown in FIG.
)).

Next, as shown in FIG. 3C, a pattern forming film 3 made of tantalum, which is an X-ray absorber, is formed by sputtering.

Next, as shown in FIG. 3D, the pattern forming film 3 is selectively etched by RIE using CI/CCl4 gas to form a pattern 3a.

Subsequently, as shown in FIG. 4(e), an adhesive made of polyimide is applied to the support frame 4 or the substrate l made of SiC,
After gluing the support frame 4 and the substrate 1 together, the temperature is 200″C.
The polyimide is solidified by heating to fix the support frame 4 and the substrate l.

Thereafter, as shown in FIG.
The exposure mask is charged and removed by an etching method using a mixed solution.

[Problem to be solved by the invention]

By the way, as shown in FIG. 4(e), after the polyimide fixing the support frame 4 and the substrate 1 is heated and solidified,
When cooling, the thermal expansion coefficients of the support frame 4 and x+Fii (respectively 4.7 xlO-b/'C, 2, 7xlo-'
/ 'C), compressive stress is generated in the support frame 4 and remains.

Therefore, as shown in FIG. 5(f), when a part of the substrate 1 is removed, the support frame 4 loses its support and tends to shrink.

At this time, if the pattern forming M3 has a compressive stress, or even if it has a tensile stress, if it is smaller than the compressive stress remaining in the support frame 4, the pattern forming film 3 will shrink due to the compressive stress, so the pattern forming film 3 will shrink. The pattern of the formed film 3 is distorted. In the figure, the normal pattern position in the case where no distortion occurs is indicated by a two-dot chain line (FIG. 5).

Conversely, if the pattern formation 11113 has a tensile stress greater than the compressive stress of the support frame 4, the pattern formation film 3 will stretch due to the tensile stress, and the pattern formed by patterning the pattern formation film 3 will be distorted. Therefore, there is a problem that the precision of the mask pattern deteriorates.

In order to solve this problem, as shown in FIGS. 6(a) to 6(c), first, a substrate 5 made of Si on which a base film 6 made of SiC and a pattern forming film 7 are formed is mounted on a support frame 8. Attachment ((a) in the same figure) Afterwards, the substrate 5 in the area through which X-rays are transmitted was removed to relieve stress on the support frame 8 ((b) in the same figure)
), the pattern forming film 7 is patterned (
(C)) However, as shown in (b) of the same figure, SiC
Since the base film 6 made of the above is thin, only a few microns thick, it does not have sufficient strength, and there is a problem that the mask will often break if care is not taken when working on it.

The present invention has been made in view of the problems of the conventional example, and can prevent distortion of the mask pattern due to stress generated when creating an exposure mask.
Another object of the present invention is to provide a method for manufacturing an exposure mask that allows such a mask to be easily created.

[Means to solve the problem]

The above-mentioned problems include a step of forming a base film on one surface of a substrate, and a step of forming a pattern forming film on the base film so that a first stress is generated in advance along the surface of the base film. , a step of patterning the pattern forming film, a step of attaching a support frame to the peripheral part of the other surface of the substrate, partially etching and removing the substrate using the support frame as a mask, and removing the base film after etching. This is achieved by a method of manufacturing an exposure mask characterized by comprising the step of offsetting the second stress appearing along the first stress with the first stress.

[For production]

According to the manufacturing method of the present invention, a pattern forming film is formed in advance so that the first stress is generated along the surface of the base film,
Thereafter, the second stress that appears along the surface of the base film after etching a portion of the substrate is offset by the first stress.

Therefore, expansion and contraction of the support frame and the pattern forming film can be prevented, so that the mask pattern formed by patterning the pattern forming film can be prevented from being distorted.

In addition, unlike conventional methods, the process of removing part of the substrate is performed at the end of the manufacturing process, so the mask can maintain sufficient strength during the work. Examples of the present invention will be described with reference to the following.

FIGS. 1(a) to 1(f) are cross-sectional views illustrating a method for creating an X-ray exposure mask according to an embodiment of the present invention.

First, a film with a thickness of about 2 μm was deposited on a substrate 9 made of St with a thickness of about 500 μm as shown in FIG. A 1° base film made of SiC is formed (FIG. 2(b)).

Next, in order to offset the stress (second stress) that appears along the surface of the base film 1o after the substrate 9 is attached to the support frame and a part of the substrate 9 is etched and removed, this stress (second stress) is applied.
stress equal in magnitude and opposite in direction (first stress)
The pattern forming film 11 is formed so as to generate a stress of 1° along the surface of the base film 1°. Now, the material of this pattern forming film 11 is a film that is an X-ray absorber and has a thickness of about 1 tl.
11 tantalum is used.

By the way, FIGS. 3(a) and 3(b) are diagrams showing the results of an experiment conducted by the inventor of the present invention to investigate stress generated in a pattern forming film made of tantalum deposited by sputtering.

Figure (a) shows how the stress generated in the pattern forming film changes when the applied power is varied while keeping the Ar gas pressure constant at 10 mTorr, and Figure (b) shows how the applied power changes when the applied power is changed to 2 kW. FIG. 3 is a diagram showing how the stress generated in the pattern forming film changes when the Ar gas pressure is kept constant and changed. In the same figure (b), with Ar sputtering,
``No'' indicates that a base Jl made of SiC is applied before forming the X-ray absorber film. It shows whether or not Ar sputtering was applied to JIO for 10 minutes at 0.2 kW.

In the experiment, a substrate made of Si was used as a substrate on which a pattern rIi was deposited, and the stress corresponding to the warp was determined by measuring the warp of the substrate when the film was deposited. Note that the positive sign of stress indicates tensile stress,
A negative sign indicates compressive stress.

As shown in FIG. 3(a), when the applied power is small, tensile stress is generated in the pattern-forming film, and when it is large, compressive stress is generated. Further, as shown in FIG. 2B, compressive stress occurs when the gas pressure is small, and tensile stress occurs when the gas pressure is large. In this way, the stress of the patterned film can be controlled over a wide range by applying power and gas pressure.

It has now been previously investigated that the second stress is a compressive stress having a magnitude of about 1 xlO' dyne/c-.

Therefore, based on the results of this investigation and the experimental results of the stress generated in the pattern forming film, for example, as shown in FIG. 3(a), the Ar gas pressure was set at 10 mTorr.

When tantalum is sputtered under the condition of applied power of 1kW,
This pattern forming film 11 has approximately IXIO' dyne/
cm'' tensile stress.

Next, as shown in FIG. 3D, the pattern forming film 11 is selectively etched by RIE using CI/CCl4 gas to form a pattern forming film.

Subsequently, as shown in FIG. 3(e), after applying an adhesive made of polyimide to the support frame 12 or the substrate 9 made of SiC and bonding the support frame 12 and the substrate 9 together, the temperature is set to 200°C.
The polyimide is solidified by heating at ℃, and the support frame 12 and base ++
ff9 is fixed. At this time, compressive stress is generated and remains in the support frame 12 due to the difference in thermal expansion coefficient between the support frame 12 and the substrate 9.

Thereafter, as shown in FIG.
It is removed by an etching method using a mixed solution of At this time, the support of the substrate 9 is lost and the support frame 12 is about to shrink, extending approximately IXIO' dy along the surface of the base 11910.
Compressive stress of ne/c- appears, but the pattern forming film 11
In advance, about IXIO' d is applied along the surface of the base film 10.
Since a tensile stress of yne/c- is applied, these stresses cancel each other out. Therefore, the pattern forming film 11 does not expand or contract, so the pattern forming film formed by patterning the pattern forming film 11 is not distorted. Thereby, a highly accurate mask pattern can be created.

In addition, as shown in FIG. 3(f), since the area of the substrate 9 through which X-rays are transmitted is removed at the end of the process, the work can be carried out while maintaining sufficient strength of the mask.

Thereby, unlike the conventional method, a mask can be easily created without paying special attention.

In this way, the X-ray exposure mask is completed.

The top view at this time is shown in FIG. 2. In the same figure, the first
The same symbols as those shown in Figures (a) to (f) are shown in Figure 1 (
The same items as those shown in a) to (f) are shown.

Although tantalum was used as the X-ray absorber in the embodiment, the present invention can also be applied to tungsten (W), gold (Au), or the like.

〔Effect of the invention〕

As described above, according to the manufacturing method of the present invention, the second stress that appears along the surface of the base film after etching/removal of a part of the substrate is applied to the pattern forming film in advance along the surface of the base film. Since it is offset by the applied first stress,
Expansion and contraction of the support frame and pattern forming film can be prevented. Therefore, distortion of the mask pattern formed by patterning this pattern forming film can be prevented.

This makes it possible to create a highly accurate mask pattern.

Furthermore, since the step of etching and removing the substrate using the support frame as a mask is performed at the end of the manufacturing process, the work can be carried out while the mask has sufficient strength.

Thereby, unlike the conventional method, a mask can be easily created without paying special attention.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view illustrating a method for creating an X-ray exposure mask according to an embodiment of the present invention, FIG. 2 is a top view of an X-ray exposure mask, and FIG. A diagram showing the relationship between the stress of the pattern forming film and sputtering conditions, FIG. 4 is a cross-sectional diagram illustrating the conventional method of creating a mask for xin light, and FIG. 5 is a diagram illustrating the problems of the conventional method. , FIG. 6 is a cross-sectional view illustrating another conventional mask manufacturing method. [Explanation of symbols] 1.5.9...Substrate, 2.6.10... Base film, 3.7.11... Pattern forming film, 3a, lla... Pattern, 4.8. 12... Support frame,

Claims (1)

[Claims] A step of forming a base film on one surface of a substrate, and forming a pattern forming film on the base film so that a first stress is generated in advance along the surface of the base film. a step of patterning the pattern forming film; a step of attaching a support frame to a peripheral portion of the other surface of the substrate; partially etching and removing the substrate using the support frame as a mask; A method of manufacturing an exposure mask, comprising the step of offsetting a second stress appearing along a base film with the first stress.