JPH04267322A - X-ray mask - Google Patents

Abstract

PURPOSE:To enable a highly accurate circuit pattern transfer through exposure to X-rays by preventing a multiple exposure to X-rays through forming a multiple-exposure prevention film on both surfaces of the frame edge of an X-ray transmission film. CONSTITUTION:An X-ray transmission film 42 of SiN, SiC, BN, etc., is formed to 1-3mum thickness on an X-ray transmission film support 41 by a CVD method or sputtering method. Then, the reverse of the X-ray transmission film support 41 is treated by wet etching so that an exposure window is formed. Subsequently, a plating electrode 43 is formed by a method such as EB or resistance heating deposition. In this case, the plating electrode on the reverse side is the external size of the pattern of a circuit on the obverse. After that, a resist pattern 44 is formed on the plating electrode 43 by a method such as electron- beam exposure. Also in this case, the position of the resist pattern 44 is caused to coincide with the plating electrode on the reverse. That is, the outsides of the obverse and reverse of the circuit pattern are caused to coincide with each other. Subsequently, the obverse and reverse are simultaneously plated 45 with gold so that a resist and plating substrate are peeled off.

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 X-ray lithography for semiconductor manufacturing.

0002

[Prior Art] Conventionally, various methods have been used as lithographic processing methods for electronic devices such as ICs and LSIs. This method has many advantages over conventional lithography methods using visible light and ultraviolet light, and is attracting attention as a promising means for quarter-micron lithography. Generally, an X-ray mask used in X-ray lithography is composed of a Si wafer substrate 21 with a thickness of 0.4 to 2 mm, an X-ray transparent film 22, and an X-ray absorber 23, as shown in the schematic cross-sectional view of the mask shown in FIG. ing. The Si substrate is etched into a circular or polygonal shape at the center, and after etching becomes a self-supporting X-ray transparent film. The X-ray absorber is formed as a circuit pattern on this self-supporting film. On the outside of the circuit pattern, an X-ray absorber 24 is formed in a solid shape to prevent X-rays from passing through.

0003

[Problems to be Solved by the Invention] In X-ray lithography using the above-mentioned X-ray mask, exposure is normally performed in a step-and-repeat manner. At this time, multiple exposure becomes a problem. On the outside of the circuit pattern 23 of the X-ray mask, an X-ray absorber 24 having the same thickness as the inside circuit pattern is formed in a solid shape to prevent X-rays from passing through. However, an X-ray absorber with the same thickness as the circuit pattern cannot completely absorb X-rays, and several to
More than 10% of the light passes through. When performing step-and-repeat exposure, this number of transmitted X-rays of several to ten-odd percent becomes a problem. In other words, it is multiple exposure. When exposure is performed step and repeat, the outer area 3 of the required exposure area 31 as shown in FIG.
2 is exposed to X-rays transmitted through the absorber 24.

In particular, the shaded area 33 is exposed to triple exposure. This exposure causes a decrease in line width accuracy and film thinning, which is a major problem. To solve this problem, proposals have been made such as increasing the thickness of the absorber outside the circuit pattern or providing an aperture separate from the mask, but the former method requires increasing the thickness of the absorber. This makes it difficult to control the internal stress of the absorber, increasing the positional distortion of the mask pattern, and the latter makes it extremely difficult to position the aperture and complicates the mechanism of the device (in particular, Therefore, the purpose of the present invention is to solve the problems of the prior art described above, to prevent multiple X-ray exposures, and to develop an X-ray system that enables highly accurate circuit pattern transfer by X-ray exposure. The purpose is to provide masks.

[0005]

[Means for Solving the Problems] The above objects are achieved by the present invention as described below. That is, the present invention provides an X-ray mask consisting of an X-ray transparent film, an X-ray absorber, and an X-ray transparent film support, in which multiple exposure prevention films are formed on both sides of the frame edge of the X-ray transparent film. This is a characteristic X-ray mask.

[0006]

[Operation] According to the present invention, multiple exposure prevention films are formed on both sides of the X-ray transparent film on the outside of the circuit pattern in the X-ray transparent film of the X-ray mask, thereby preventing multiple exposure to X-rays. At the same time, it is possible to reduce positional distortion of the mask pattern caused by providing the multiple exposure prevention film. Furthermore, by using a gold plating film to form both sides of the multiple exposure prevention film, pattern position distortion caused by the formation of the multiple exposure prevention film can be substantially eliminated.

[0007]

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing one embodiment of an X-ray mask according to the present invention. In FIG. 1, 1 is an X-ray transparent membrane support, 2 is an X-ray transparent membrane, 3 is an X-ray absorber, and 4 is a multiple exposure prevention membrane.

Example 1 FIG. 4 shows an example of the manufacturing process of the X-ray mask of the present invention. First, as shown in FIG. 4(a), SiN, SiC, and BN are deposited on a substrate (X-ray transparent membrane support 41) made of Si, quartz, etc.
An X-ray transmitting film 42 such as the above is formed to a thickness of 1 to 3 μm by CVD or sputtering. Next, as shown in FIG. 4(b), an exposure window is formed by subjecting the back surface of the X-ray transparent film support 41 to a wet etching process. Next, Figure 4 (
As shown in c), a plating electrode 43 is formed by a method such as EB or resistance heating vapor deposition. At this time, the plating electrode on the back side is made to have a size outside the circuit pattern on the front side. Next, as shown in FIG. 4(d), a resist pattern 44 is formed on the plating electrode 43 by a method such as electron beam exposure. Also at this time, the position of the resist pattern is aligned with the plating electrode on the back side. In other words, match the outside of the circuit pattern face to face. Subsequently, as shown in FIG. 4(e), gold plating 45 is performed on the front and back surfaces at the same time, and the resist and plating base are peeled off to obtain the X-ray mask of the present invention. Further, gold plating may be performed sequentially on the front and back sides instead of at the same time, but in this case, the film thickness should be made as uniform as possible.

Example 2 FIG. 5 shows another example of the manufacturing process of the X-ray mask of the present invention. First, as shown in FIG. 5(a), an X-ray transparent film 52 made of SiN, SiC, BN, etc. is deposited on a substrate (X-ray transparent film support 51) made of Si, quartz, etc. to a thickness of 1 to 3 μm by CVD or Formed by sputtering method or the like. Next, as shown in FIG. 5(b), a plating electrode 53 is formed at the position where the multiple exposure prevention film is to be formed. Next, as shown in FIG. 5C, an X-ray absorber layer 54 made of WNx, Ta, W, etc. is formed on the X-ray transparent film 52 by sputtering, CVD, or the like. Next, as shown in FIG. 5(d), a resist pattern 55 is formed on the X-ray absorber by a method such as electron beam exposure. Next, as shown in FIG. 5e, an X-ray absorber pattern 56 is formed using the resist pattern 55 as an etching mask, and after etching, the resist is peeled off. Next, as shown in FIG. 5(f), the plating electrode 53
is formed on the back side of the outer position of the circuit pattern. Next, as shown in FIG. 5(g), gold plating is performed on the plating electrodes simultaneously or sequentially to form an X-ray mask of the present invention. Note that the present invention is not limited to the above embodiments, and various modifications are possible.

0010

As described above, according to the X-ray mask of the present invention, multiple exposure, which has been a big problem in the past, can be solved and accurate line width control can be performed. Furthermore, since the same multiple exposure prevention film is formed on both sides of the X-ray transparent film, the internal stress generated by the formation of the multiple exposure prevention film can be canceled out by itself, without affecting the position of the circuit pattern. A film to prevent multiple exposure can be formed. Therefore, highly accurate circuit pattern transfer by X-ray exposure is possible.

[0011]

[Brief explanation of the drawing]

FIG. 1 is a sectional view schematically showing an X-ray mask of the present invention.

FIG. 2 is a cross-sectional view schematically showing a prior art X-ray mask.

FIG. 3 is a diagram illustrating multiple X-ray exposure.

FIG. 4 is a diagram showing an example of the manufacturing process of the X-ray mask of the present invention.

FIG. 5 is a diagram showing another example of the manufacturing process of the X-ray mask of the present invention.

[Explanation of symbols]

1, 21, 41, 51: X-ray transparent membrane support 2, 22, 4
2, 52: X-ray transparent film 3, 23, 54: X-ray absorber 4: Multiple exposure prevention film 31: X-ray necessary exposure area 32: X-ray exposure area 33: Multiple exposure area 43: Plating electrode 44, 55 : Resist pattern 45: Plating film 53: Plating electrode 56: X-ray absorber pattern 57: Plating film

Claims (2)

[Claims] 1. An X-ray mask comprising an X-ray transparent film, an X-ray absorber, and an X-ray transparent film support, characterized in that a multiple exposure prevention film is formed on both sides of the frame edge of the X-ray transparent film. X-ray mask. 2. The X-ray mask according to claim 1, wherein the multiple exposure prevention film is a gold plating film.