JPH06188177A - X-ray mask and method of manufacturing the same - Google Patents

Abstract

(57) [Abstract] [PROBLEMS] To provide an X-ray mask having an X-ray absorption pattern having a capability of reliably blocking transmission of X-rays despite having a fine pattern. [Structure] An X-ray transparent support film 4 is formed on the surface of the support frame 1. The back surface of the support film 4 has a first X-ray absorbing first
W pattern 3 is formed. An X-ray absorbing second W pattern 5 having the same pattern as the first W pattern is formed on a portion of the surface of the support film 4 facing the first W pattern 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an X-ray mask used in a semiconductor device manufacturing process and a method for manufacturing the X-ray mask.

[0002]

2. Description of the Related Art In recent years, miniaturization of elements has been required as semiconductor devices, especially large-scale integrated circuit (LSI) devices, have higher density and higher speed. In the LSI manufacturing process,
The shorter the wavelength of light used in the photo-etching process, the finer the element can be formed. The X-ray exposure method for forming is regarded as promising.

A conventional X-ray mask used in the X-ray exposure method will be described below with reference to FIG.

As shown in FIG. 6, in the conventional X-ray mask, a SiO ₂ film 2 having a thickness of 0.1 μm which is an antireflection film is formed on a Si wafer 1 having a thickness of 2 mm which is a support frame. the SiO ₂ film X-ray transparent Si ₃ having a thickness of 2μm is a supporting film of N ₄ film 4 on the 2 are formed, the Si ₃ N ₄
On the film 4, a W pattern 5 made of an X-ray absorber and having a thickness of 0.8 μm is formed.

In the X-ray exposure method, since there is no refraction lens for X-rays having a short wavelength, the X-ray mask and the wafer are opposed to each other with a small gap therebetween and irradiated with X-rays to form an X-ray mask. It is necessary to transfer the formed pattern as it is to the Si wafer 1. For this reason, the W pattern 5 is required to have a sufficient thickness to prevent the transmission of the irradiated X-rays and to be formed in the same size as the pattern to be transferred. Therefore,
For example, when transferring a pattern having a width of 0.2 μm, the W pattern 5 is required to have a thickness of 0.8 μm and a width of 0.2 μm.

Then, in order to form the W pattern 5, a selective etching method is usually used. That is, the W pattern 5 is formed by forming a resist pattern on the W film and etching the W film by a dry etching method or the like using the resist pattern as a mask and using a reactive gas.

Further, a thin film having a mask effect, for example, a SiO ₂ film is formed on the W film during etching, the SiO ₂ film is etched using the resist pattern as a mask, and then the W film is etched using the formed SiO ₂ pattern as a mask. You can also do it.

[0008]

However, as described above, the X-ray absorption pattern formed on the support film, for example, the W pattern, has a thickness sufficient to prevent X-ray transmission, for example, 0.8 μm. Has a large thickness of
Since the resist pattern formed on the W film is damaged during etching or a so-called side etching phenomenon in which the etching proceeds in the lateral direction occurs, the W pattern may become thin, and a fine W pattern is formed with high accuracy. It was difficult to do. That is, in the X-ray absorption pattern of the conventional X-ray mask, there is a problem that it is difficult to achieve both the ability to reliably block X-ray transmission and the fine pattern shape.

Further, when the W film is etched using the SiO ₂ film pattern on the W film as a mask, there is also a problem that the W pattern becomes thin due to the side etching phenomenon.

In view of the above, it is an object of the present invention to provide an X-ray mask having an X-ray absorption pattern having the ability to reliably block X-ray transmission despite having a fine pattern. .

[0011]

In order to achieve the above-mentioned object, the invention of claim 1 provides X-ray absorption patterns of the same pattern on the front and back surfaces of the X-ray transparent support film at mutually opposing portions. Each is formed.

[0012] Specifically, the means for solving the problems according to the invention of claim 1 is that the X-ray mask has a first structure comprising an X-ray absorber on the back surface of an X-ray transparent support film formed on the surface of the support frame. The X-ray absorption pattern is formed, and X is formed on a portion of the surface of the support film facing the first X-ray absorption pattern.
A second X-ray absorption pattern made of a line absorber and having the same pattern as the first X-ray absorption pattern is formed.

A second aspect of the present invention is a method for manufacturing the X-ray mask according to the first aspect of the present invention, in which a first X-ray absorption pattern made of an X-ray absorber is formed on the surface of the support. And a step of forming an X-ray transparent support film on the surface of the support on which the first X-ray absorption pattern is formed, and an X-ray absorption film comprising the X-ray absorber on the surface of the support film. A step of forming a support frame by etching the exposed area of the support from the back surface side, a step of forming a resist film on the surface of the X-ray absorbing film, and a back surface side of the support frame. A step of irradiating the resist film with X-rays using the first X-ray absorption pattern as a mask to selectively expose the resist film, and then developing the resist film to form a resist pattern; X-ray using the resist pattern A structure and a step of forming a second X-ray absorbing pattern on the surface of the support film by selectively etching the Osamumaku.

[0014]

According to the structure of the first aspect, the first and second X-ray absorption patterns having the same pattern are formed on the back surface and the front surface of the support film, which are opposed to each other, respectively. The irradiated X-rays are surely blocked from being transmitted by the two X-ray absorption patterns consisting of the first and the second. On the other hand, both the first and second X-ray absorption patterns need only have the thickness necessary to block X-rays, that is, the thickness of the conventional X-ray absorption pattern.
The thickness of each of the first and second X-ray absorption patterns is
About half the conventional X-ray absorption pattern will suffice.

According to the structure of claim 2, since the X-ray transparent support film is formed on the surface of the support on which the first X-ray absorption pattern is formed, the first X-ray pattern is formed on the back surface of the support film. Will be formed.

Since the resist pattern is formed by irradiating the resist film formed on the surface of the support film from the back side of the support frame with X-rays using the first X-ray absorption pattern as a mask, the resist pattern is formed. It has the same pattern as the first X-ray absorption pattern. Further, since the second X-ray absorption pattern is formed by etching the X-ray absorption film formed on the surface of the support film using the resist pattern as a mask, the first X-ray absorption pattern on the surface of the support film is formed. A second X-ray having the same pattern as the first X-ray absorption pattern at a portion facing the X-ray absorption pattern of
A line absorption pattern will be formed.

[0017]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic sectional view of an X-ray mask according to an embodiment of the present invention. As shown in FIG. 1, the X-ray mask is a support frame of a Si wafer 1 having a thickness of 2 mm. A Si ₃ N ₄ film 4 having a thickness of 2 μm, which is an X-ray transparent support film, is formed on the front surface, and a 0.4 μm thick film having a thickness of 0.4 μm as a first X-ray absorption pattern is formed on the back surface of the Si ₃ N ₄ film 4. The second X pattern having the first W pattern 3 and the same pattern as the first W pattern 3 on the surface of the Si ₃ N ₄ film 4 is formed.
A second W pattern 5 having a thickness of 0.4 μm is formed as a line absorption pattern. In other words, the first W pattern 3 and the second W pattern 5, the Si ₃ N ₄ in and the front and rear surfaces of the Si ₃ N ₄ film 4 have the same pattern with each other
It is formed at a portion facing each other with the film 4 interposed therebetween. On the back surface of the first W pattern 3, a thickness of 0.
A 1 μm SiO ₂ film 2 is formed.

2 to 5 are partial sectional views showing respective steps in the method of manufacturing the X-ray mask.

First, as shown in FIG. 2, a SiO ₂ film 2 having a thickness of 0.1 μm as an antireflection film is formed on the surface of a Si wafer 1 which is a support having a thickness of 2 mm, and then the SiO ₂ film is formed.
₂ The first W film having a thickness of 0.4 μm is formed on the surface of the film 2,
Then, an electron beam (EB) exposure method and a dry etching method are applied to the first W film to form a first W pattern 3 as a first X-ray absorption pattern on the surface of the SiO ₂ film 2. To do.

Next, as shown in FIG. 3, on the SiO ₂ film 2 and the first W pattern 3 was formed Si ₃ N film ₄ 4 thick 2μm as X-ray transparent supporting film Later, the Si
₃ N to form the second W film 5A thick 0.4μm on the membrane ₄ 4.

Next, as shown in FIG.
After etching the pattern formation region from the back surface side with an alkaline etching solution such as KOH, the second W
A positive resist film 6 is formed on the surface of the film 5A, and thereafter, X-rays having a wavelength of 1 nm are irradiated from the back surface side of the Si wafer 1.

With the above arrangement, the first W pattern 3
The X-rays applied to the region where the film is not formed pass through the second W film 5A and expose the resist film 6 while the intensity of the X-ray is attenuated by the second W film 5A. by the way,
When the X-rays pass through the W pattern, the intensity of the X-rays attenuates exponentially with respect to the thickness of the W film of the W pattern.
The intensity of X-rays transmitted through both the first W pattern 3 and the second W film 5A is reduced to about 1/20 of the intensity of X-rays transmitted through only the second W film 5A. Thus, the first
The X-rays radiated to the area where the W pattern 3 of
Since the strength is remarkably attenuated by the first W pattern 3 and the second W film 5A, the resist film 6 cannot be exposed to light.

Next, the resist film 6 is developed to form a resist pattern on the portion of the second W film 5A facing the first W pattern 3. afterwards,
The second W is formed by a dry etching method using a reactive gas.
When the film 5A selectively etched, the second W pattern 5 is formed on the Si ₃ N film ₄ 4.

As described above, the first W pattern 3
Alternatively, when forming the second W pattern 5, the W film having a thickness of 0.4 μm may be selectively etched. Therefore, when the W film is etched, the resist pattern is not significantly damaged or the side etching of the W pattern does not increase, so that a fine W pattern can be formed with high accuracy.

In the opaque portion of the X-ray mask formed as described above, the first and second Ws having the same pattern are formed at the portions facing each other with the Si ₃ N ₄ film 4 interposed therebetween.
Since the patterns 3 and 5 are formed, the first and second W patterns 3 and 5 absorb X-rays during exposure, and the intensity of X-rays can be sufficiently reduced.

In the above embodiment, the Si ₃ N ₄ film 4 is used as the support film and the W film is used as the X-ray absorber. Instead of this, a dielectric film such as a SiC film is used. An X-ray absorber made of a metal such as a supporting film or Ta may be used.

Further, in the above embodiment, SiO ₂ as an antireflection film is formed on the back surface of the Si ₃ N ₄ film 4 which is a supporting film.
Although the film 2 is formed, the SiO ₂ film 2 may be formed on both sides of the support film, and the effect of the present invention is not diminished without the SiO ₂ film.

Further, the X-rays irradiated from the back surface side of the Si wafer 1 to form the second W pattern 5 have the same wavelength as the X-rays used for exposure using the X-ray mask according to this embodiment. It does not have to be, the first W pattern 3 and the second W
Transmission of light is blocked in the region where the film 5A overlaps, while X of a wavelength that allows transmission in the region of the second W film 5A only.
It is desirable to choose a line.

[0030]

According to the first aspect of the invention, first and second X-ray absorption patterns made of an X-ray absorber and having the same pattern are formed on the back surface and the front surface of the support film facing each other. Therefore, the X-rays irradiated during the X-ray exposure are surely blocked from being transmitted by the two X-ray absorption patterns consisting of the first and second X-ray absorption patterns, while the X-rays of the first and second X-ray absorption patterns are respectively prevented. Since the thickness of the X-ray can be about half that of the conventional X-ray absorption pattern, an X-ray mask with an X-ray absorption pattern that has the ability to reliably block X-ray transmission despite having a fine pattern is realized. it can.

According to the invention of claim 2, since the X-ray transparent support film is formed on the surface of the support on which the first X-ray absorption pattern is formed, the first X-ray pattern is formed on the back surface of the support film. A resist pattern is formed by using the first X-ray absorption pattern as a mask, and the X-ray absorption film formed on the surface of the support film is etched by using the resist pattern as a mask. In order to form the X-ray absorption pattern of No. 2, the first X-ray absorption pattern is formed on the surface of the support film at a portion facing the first X-ray absorption pattern.
Since the second X-ray absorption pattern having the same pattern as the X-ray absorption pattern is formed, the X-ray absorption mask according to the invention of claim 1 can be formed easily and reliably.

[Brief description of drawings]

FIG. 1 is a sectional view showing the structure of an X-ray mask according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing each step of the manufacturing method of the X-ray mask.

FIG. 3 is a cross-sectional view showing each step of the method for manufacturing the X-ray mask.

FIG. 4 is a cross-sectional view showing each step of the method for manufacturing the X-ray mask.

FIG. 5 is a cross-sectional view showing each step of the method for manufacturing the X-ray mask.

FIG. 6 is a sectional view showing the structure of a conventional X-ray mask.

[Explanation of symbols]

1 Si wafer (support, support frame) 2 SiO ₂ film 3 First W pattern (first X-ray absorption pattern) 4 Si ₃ N ₄ film (support film) 5 Second W pattern (second X pattern) Line absorption pattern) 5A Second W film 6 Resist film

Claims (2)

[Claims] 1. A first X-ray absorption pattern composed of an X-ray absorber is formed on the back surface of an X-ray transparent support film formed on the surface of a support frame, and the above-mentioned surface of the support film is formed. An X-ray, characterized in that a second X-ray absorption pattern made of an X-ray absorber and having the same pattern as the first X-ray absorption pattern is formed at a portion facing the first X-ray absorption pattern. mask. 2. A first member comprising an X-ray absorber on the surface of a support.
Forming an X-ray absorption pattern, forming a X-ray transparent support film on the surface of the support on which the first X-ray absorption pattern is formed, and absorbing X-rays on the surface of the support film. A step of forming an X-ray absorbing film made of a body, a step of forming a support frame by etching the exposed region of the support from the back side, and a step of forming a resist film on the surface of the X-ray absorbing film. The resist pattern is formed by irradiating the resist film with X-rays from the back side of the support frame using the first X-ray absorption pattern as a mask to selectively expose the resist film, and then developing the resist film. And a step of forming a second X-ray absorption pattern on the surface of the support film by selectively etching the X-ray absorption film using the resist pattern. X-ray machine Method of manufacturing a click.