JPH04144118A - X-ray exposing mask - Google Patents

Abstract

PURPOSE:To eliminate pattern errors in time of forming minute patterns and to diminish stress-strain in the direction of a mask board surface, by providing an intermediate layer for absorbing stresses produced between the mask board and an X-ray absorber in time of forming an absorber pattern. CONSTITUTION:An intermediate layer 8 is made of tungsten sulfide being a laminar compound having a crystal layer in the horizontal direction to a mask board 1 between the board and an absorber film. This can ease shrinkage stresses produced in time of forming an absorber pattern 2 by patterning the absorber film, by the rearrangement of forces working between the layers. As a result, the absorber pattern 2 does not exfoliate, and X-ray exposing masks without the size errors of patterns can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an exposure mask used in lithography for microfabrication of semiconductor devices, and particularly to one that performs irradiation using X-rays.

[Conventional technology]

Currently, when manufacturing semiconductor devices, a resist is applied to the surface of a silicon wafer to form a photoresist film, a latent image is formed by irradiation with radiation, and then a negative or positive image is formed by developing the image. The pattern is obtained using lithographic techniques.

With the increasing integration, density, and miniaturization of Tokoroka, IC, LSI, and vLS■ semiconductor devices, 0.3μ
There is a need for a technology that can form fine patterns with a diameter of less than m. However, traditional Deep UV light, mercury i
It is extremely difficult to respond to the above-mentioned miniaturization with lithography technology that utilizes a line emission line spectrum or a KrF excimer laser. For this reason, lithography technology using X-ray exposure with extremely short wavelengths is being researched.

FIG. 2 shows a cross-sectional view of an example of a conventional mask structure for X-ray exposure. In the figure, 1 is a mask substrate that supports the mask, 2 is an absorber pattern with a high X-ray absorption coefficient, and 3 is a mask substrate support.

Next, the operation will be explained using FIG. 3.

The X-rays irradiated onto the mask pass through the mask substrate 1. However, among the X-rays that have passed through the mask substrate 1, those that reach the absorber pattern 2 are absorbed by the absorber, and their intensity is weakened. In this way, an X-ray pattern corresponding to the absorber pattern is formed.

As described above, the X-ray pattern size required for X-ray exposure lithography is becoming finer, and it is important to accurately form the absorber pattern 2.

Next, a conventional method of forming an X-ray exposure mask will be explained using FIG. An X-ray absorber film 4 made of metal is deposited over the entire surface of the mask substrate l by sputtering or the like. Furthermore, a resist pattern 5 corresponding to a desired pattern is formed, and then the absorber film 4 is etched using this resist as a mask to form a desired absorber pattern 2.

[Invention or problem to be solved]

The conventional X-ray exposure mask is constructed as described above, but the mask substrate l is made of a material that does not deform due to strain or external stress so as to prevent deformation of the absorber pattern 2. Conventionally, silicon nitride, boron nitride, etc. have been used as such materials. Furthermore, tungsten has been used as the material for the absorber film 4.

By the way, as described above, tungsten is formed in the form of a film on the mask substrate 1 by sputtering or the like. At this time, as shown in FIG. 5, a stress 6 is applied in the outward direction of the mask substrate 1 within the absorber film 4 made of tungsten. However, when the absorber film 4 is patterned by photolithography, the stress 6 is released and the shrink window cuff is activated. Focusing on one particular pattern, as shown in FIG. 6, the contraction window cuff works, causing the absorber pattern 2 and even the mask substrate 1 below it to become distorted.

This pattern distortion causes pattern dimensional errors and also causes problems such as peeling of the X-ray absorber.

This invention was made in order to solve the above-mentioned problems, and it is possible to obtain an X-ray exposure mask that does not cause pattern errors when forming fine patterns, and also to reduce stress strain in the direction of the surface of the mask substrate. It is an object of the present invention to obtain an X-ray exposure mask that can solve the problem.

[Means to solve the problem]

The X-ray exposure mask according to the present invention is provided with an intermediate layer between the mask substrate and the X-ray absorber for absorbing stress generated during formation of the absorber.

Further, a layered compound is used as the intermediate layer.

[Effect]

In this invention, since the intermediate layer is provided between the mask substrate and the absorber, it is possible to absorb or buffer the strain caused by stress when forming the absorber on the mask substrate, and as a result, it is possible to absorb or buffer the dimensional error of the mask pattern. It can also prevent peeling of the body.

Furthermore, since a layered compound is used as the intermediate layer, stress strain can be alleviated by utilizing rearrangement of forces acting between layers, such as van der Waals stress.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. 1st
The figure is a sectional view of an X-ray exposure mask according to an embodiment of the present invention. In the figure, ■ is a mask substrate made of, for example, silicon nitride, 2 is an X-ray absorber pattern made of, for example, tungsten metal, 3 is a mask substrate support made of, for example, silicon, and 8 is a mask substrate 1 and an X-ray absorber pattern 2. This is an intermediate layer formed of a material made of tungsten sulfide, for example.

Since the intermediate layer 8 made of tungsten sulfide is a layered compound, it is brittle against stress in a direction parallel to the layer. For example, even if a horizontal stress is applied to one layer, that stress does not directly contribute to a different layer as strain, but is relieved by the force acting between the eyebrows, for example, the rearrangement of van der Waals stress between the layers. Therefore, in the manufacturing process of the above-mentioned X-ray exposure mask, the shrinkage stress of the tungsten metal absorber film 4 is released by the stress relaxation effect of the tungsten sulfide 8, and the mask absorber film 4 is not deformed during pattern formation and can be formed as desired. An absorber pattern 2 is obtained.

According to this embodiment, since the intermediate layer made of tungsten sulfide, which is a layered compound, is provided between the mask substrate l and the absorber film 4, the absorber film 4 is patterned to form the absorber pattern 2. The shrinkage window cuff that occurs during formation can be alleviated by rearranging the force acting on the glabella.
As a result, the absorber pattern 2 does not peel off, and a desired X-ray exposure mask without pattern dimensional errors can be obtained.

In the above embodiments, tungsten sulfide was used as the material for the intermediate layer 8, or other materials such as cadmium iodide were used.

A layered compound such as graphite may also be used.

〔Effect of the invention〕

As described above, according to the X-ray exposure mask according to the present invention, since the intermediate layer for relieving shrinkage stress is provided between the mask substrate and the X-ray absorber, the X-ray exposure mask can be manufactured easily. The generated stress between the mask substrate and the X-ray absorber can be eliminated, and since a layered compound is used as the intermediate layer, the stress can be reduced by utilizing the rearrangement of the forces acting between the layers, such as van der Waals stress. As a result, it is possible to obtain an X-ray exposure mask that does not cause dimensional errors in the X-ray absorber pattern.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an X-ray exposure mask according to an embodiment of the present invention, FIG. 2 is a sectional view of a conventional X-ray exposure mask, and FIG. 3 is a diagram for explaining the function of the mask. Figure 4 is a cross-sectional view showing the manufacturing process of a conventional X-ray exposure mask;
FIG. 6 and FIG. 6 are diagrams for explaining problems with conventional X-ray exposure masks. In the figure, l is the mask substrate, 2 is the X-ray absorber pattern, 3 is the mask substrate support, 4 is the X-ray absorber film, 5 is the resist pattern, 6 is the tensile stress, 7 is the shrinkage stress, and 8 is the intermediate layer. It is. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (2)

[Claims] (1) A mask substrate, an absorber provided in a pattern on the mask substrate, and an absorber provided between the mask substrate and the absorber to alleviate stress generated between the substrate and the absorber. An X-ray exposure mask characterized by comprising an intermediate layer. (2) The X-ray exposure mask according to claim 1, wherein the intermediate layer is made of a material having a crystal layer in a direction horizontal to the substrate.