JPH01302723A - Mask for x-ray exposure and manufacture thereof - Google Patents

Abstract

PURPOSE:To form a pattern in a good shape without decreasing a reflectance of a multilayer film reflecting mirror by making an X-ray exposure mask by a method wherein multilayer film reflecting mirror is formed on a substrate and then a reflection prevention film is formed according to a desired pattern on the multilayer film reflecting mirror. CONSTITUTION:A multilayer film reflecting mirror 2 is formed on a mask substrate 1 and then a reflection prevention film 4 is formed on the multilayer film reflecting mirror 2 according to a desired pattern 3, to make an X-ray exposure mask. For formation of the reflection prevention film 4 on the multilayer film reflecting mirror 2 according to a desired pattern, a resist coating process, a development process and a peeling process are required. However, the multilayer film reflecting mirror gets less damage in these processes compared with an etching process. What's more, a processing accuracy and a reliability can be remarkably increased since a circuit can be written by an EB lithographic equipment.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to a mask for x m tv light and a method for manufacturing the same.

(Conventional technology) Currently, photolithography technology that uses light as an exposure medium is used on production lines, but this technology has a resolution limit determined by the wavelength used. Research and development of X-ray exposure technology that uses X-rays, which have shorter wavelengths than light, is making rapid progress.

Conventionally well-known X-ray exposure technology uses a transmission mask, holds the mask and sample in parallel with an interval of the order of 10 μs, irradiates X-rays from the back of the mask, and uses the X-rays that have passed through the mask substrate. The method was to expose the photosensitizer on the sample to light. However, such a transmission type mask has many practical difficulties.

First, in order to maintain the intensity of transmitted X-rays, the mask substrate has a very thin thickness of 1 to 2 μs, and its mechanical strength is weak, making it easy to handle. Furthermore, due to the presence of a heavy metal pattern on the substrate, stress generated on the substrate tends to cause distortion in the mask pattern.

In addition, the material transmittance of 6 X-rays, which has problems with X and W wavelengths, decreases as the wavelength becomes longer, so even with a transmission mask,
The wavelength of X-rays that can pass through the mask substrate is 10 Å
It is as follows. However, the sensitivity of conventional photosensitizers peaks at longer wavelengths. In addition,
As for the line optical system, it is easier to obtain a long wavelength of around 100 Å than a short wavelength of 10 Å or less.

On the other hand, until now, the reflectance of X-rays has been virtually zero except at oblique incidence. However, with advances in technology for forming thin films, it is becoming possible to form multi-layer single-distance reflecting mirrors that can obtain high reflectance even when directly incident on the light.

The wavelength and bandwidth of the reflected X-rays can be selected relatively freely depending on the design of the multi-layer single reflector.

In addition, there is a report that a direct incidence reflectance close to 50% has been obtained at the experimental level (Applied 0pti
cs.

vol, 24. No. 6, P2S5) Therefore, a reflection type X-ray mask using a multilayer film reflecting mirror has begun to be considered.

The reflective mask formed by this multilayer reflective mirror is
A pattern is constructed depending on the presence or absence of reflection. A proposal has been made to determine the presence or absence of reflection by processing the surface of a multilayer film with a focused ion beam, as shown in FIG. However, with this method, damage to the peripheral multilayer film due to heat generated by ion beam irradiation and redeposition of etching substances are expected. Furthermore, there are many problems such as processing accuracy caused by the large beam diameter and the time it takes to write, making it extremely difficult to use mask pattern writing using a focused ion beam on an actual production line. be.

(Problems to be Solved by the Invention) In this way, the X-ray reflective mask solves the drawbacks of conventional X-ray transmissive masks: the problem of mask strength, the problem of mask distortion, and the problem of long wavelength cut. However, since the structure of the multilayer film reflecting mirror forming the single-reflection mask is very fine, it is necessary to minimize damage to the multilayer film during processes such as patterning. However, the currently proposed pattern drawing using focused ion beams causes damage to the surrounding multilayer film due to the heat generated.

There are many problems such as reattachment of etched materials, processing accuracy, and time required for drawing, so that it cannot be practically used for manufacturing masters.

The present invention was made in order to improve the above-mentioned problems, and an object of the present invention is to provide a reflective X-ray mask in which a multilayer film structure is well maintained, a high reflectance, and a good pattern, and a method for manufacturing the same. do.

[Structure of the invention]

(Means for Solving the Problems) In order to solve the above problems, the present invention provides a mask substrate.
- Provided is an X-ray exposure mask comprising a multilayer reflective mirror formed on the surface of the mirror, and an anti-reflection film formed thereon according to a desired pattern.

The present invention also includes at least a step of forming a multilayer film reflecting mirror on a mask substrate, a step of applying a resist on the multilayer film reflecting mirror formed by this step, drawing a desired pattern, and then developing it. A method for manufacturing an X-ray exposure mask is provided, which includes a step of forming an antireflection film on the multilayer film reflector exposed by the developing step, and a step of peeling off the resist after this step.

(Function) According to the present invention, in order to form an antireflection film according to a desired pattern on the surface of a multilayer reflective mirror, the steps of resist application, development, and peeling are performed, and this step includes ion beam irradiation, etc. Compared to etching, the multilayer reflector suffers only a small amount of damage.

Furthermore, since drawing can be performed using an EB drawing device, problems with processing accuracy and reliability can be greatly improved. Furthermore, since patterning is performed using a resist, once one mask is made, another mask can be made by X-ray transfer, which also solves the time problem. As a result, a reflective X-ray mask having a good pattern shape can be manufactured on an actual production line without reducing the reflectance of the multilayer mirror.

(Example) FIG. 1 is a sectional view showing the manufacturing process of an X-ray exposure mask according to an example of the present invention.

First, as shown in Fig. 1(a), the diameter is 3'φ and the thickness is 400μ.
On the surface of the silicon substrate 1 of s, 30 layers of tungsten (W) and carbon (C) multilayers 2 were alternately deposited using an EB evaporation apparatus to a thickness of 20 and 40 layers, respectively, as a reflecting mirror. As a result, a reflectance of 15% was obtained for X-rays having a wavelength of CKα of 44.7 people with a peak at an oblique incidence angle of 23'.

Next, as shown in FIG. 1(b), a resist 3 was coated on the surface of the multilayer film 2, drawn with an EB drawing device, and then developed to form an L&S pattern of 0.5 lnn.

Thereafter, as shown in FIG. 1(c), C
100 people and 60 people deposited W. In general, a multilayer film of W and C acts as a reflective mirror when the film is thin, and as an anti-reflection film when the film is thick, but the specific film thickness should be determined by considering the wavelength and incidence angle of the X-rays. Determined by

Next, as shown in FIG. 1(d), the resist 3 was peeled off, and an L&S pattern of an antireflection film 4 was formed. The reflectance of the multilayer reflective tet2 after patterning was 15%, and no decrease in reflectance due to damage during the patterning process was observed. Furthermore, when the cross section of the pattern was observed using an SEM, it was confirmed that the pattern had an ideal shape with no taper. Using this mask, one-to-one transfer was performed with a cylindrical mirror 6 using an SOR support 5 as shown in FIG. Sample 7 is one in which a multilayer film is formed on a mask substrate, and a resist is applied thereon. After the transfer, the resist of sample 7 was developed, an anti-reflection film 1 was deposited, and the resist was peeled off. As a result, a reflective mask in which an L&S pattern with a dimensional difference of 0.1 ρ or less was formed was manufactured.

According to this example, the X-ray reflectance can be improved by avoiding methods that cause large damage to the multilayer film 9 reflecting mirror and pattern shape, such as etching with ion beam irradiation, and by patterning using a method that does not cause damage, such as resist coating and peeling. A reflective X-ray mask with a high height and a good pattern shape could be manufactured. Furthermore, we were able to demonstrate that it is possible to manufacture masks with similar patterns from one mask by X-ray transfer.

Note that the present invention is not limited to the embodiments described above. For example, the multilayer film reflecting mirror and antireflection film are not limited to a multilayer film of W and C, but may also be made of MO and C, Mo and 81, or the like. In addition to heavy metal thin films, resists and the like can also be considered. In addition, the substrate is not limited to Si, but also quartz, SiC
, BN, etc. are possible. In addition, various modifications can be made without departing from the gist of the present invention.

〔Effect of the invention〕

As described in detail above, according to the present invention, it is possible to manufacture a reflective X-ray mask having a good pattern shape without reducing the reflectance of the multilayer mirror. Furthermore, it becomes possible to manufacture masks by X-ray exposure.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view showing the manufacturing process of a reflective mask for X-ray exposure according to an embodiment of the present invention, and Fig. 2 is a sectional view showing the manufacturing process of a reflective mask for X-ray exposure according to an embodiment of the present invention. 1
FIG. 3 is a cross-sectional view showing a conventional method for manufacturing a reflective mask. 1...Silicon substrate 2...Multilayer film reflecting mirror 3...
・Resist 4...Anti-reflection film 5...SO
R light 6...Cylindrical mirror 7...Sample representative Patent attorney Noriyuki Chika Yudo Mitsuyuki Matsuyama

Claims (2)

[Claims] (1) An X-ray exposure mask characterized in that a multilayer film reflecting mirror is formed on a mask substrate, and an antireflection film is formed thereon according to a desired pattern. (2) forming a multilayer film reflector on the mask substrate;
A step of applying a resist on the multilayer film reflector formed in this step and developing the drawn pattern in a desired pattern, and applying an antireflection film on at least the multilayer film reflector exposed by the development step. 1. A method for manufacturing an X-ray exposure mask, comprising the steps of forming the resist, and peeling off the resist after this step.