JPH01278723A - Mask for x-ray aligner - Google Patents

Abstract

PURPOSE:To prevent the deformation and deterioration in positional precision of an X-ray shielding pattern from occurring simultaneously enabling the thickness of a protective film to be thinned for augmenting the contrast in X-ray intensity on a substrate to be exposed by a method wherein an X-ray absorbing body comprising laminated X-ray reflecting films is used as a shielding body from X-rays. CONSTITUTION:100 pairs of W layers 4 and Be layers 5 comprising one period are laminated lastly depositing the W layer 4 to constitute an X-ray reflecting film and then a W layer 6 is deposited as an X-ray absorbing body on the surface of the last W layer 4. A part of X-rays is reflected by the X-ray reflecting film while the residual X-rays are absorbed into the X-ray absorbing body. Since around half of the X-rays are reflected by the laminated X-ray reflecting film, the temperature of a mask itself is restrained from rising. Furthermore, the levels of photoelectrons and Auger electrons generated in the X-ray shielding body are reduced to lessen the effect of these electrons for exposing the substrate to be exposed near the part below the X-ray shielding body enabling the thickness of a protective film to be made thinner than conventional film. Through these procedures, the change in shape and the deterioration in positional precision of an X-ray shielding pattern are reduced to augment the contrast in the X-ray intensity on the substrate to be exposed.

Description

[Detailed description of the invention] Industrial applications The present invention relates to an X-ray exposure mask.

BACKGROUND OF THE INVENTION A conventional X-ray exposure mask, as shown in FIG.
It consists of a mask substrate 11 for aX light, a shielding pattern 12 which is an X-ray shield formed on the lower surface of this mask substrate 11, and a protective film 13 formed on the lower surfaces thereof. The mask substrate 11 is made of a thin film of a relatively light element such as boron nitride, which is similar to silicon nitride, and has a thickness of about several μm, and the shielding pattern 12 is made of tungsten (W).
0.0 of heavy metals such as gold (Au), tantalum ('ra), etc.
It is formed of a thin film with a thickness of about 5 μm. (ANw
A13 is formed of the same material as the mask substrate 11 or spin-coated polyimide having a thickness of about 1 to several μm.

In the above configuration, X-rays are incident from above and are attenuated in the portion of the shielding pattern 12 because the absorption coefficient for the X-rays is large, and in the portion other than the shielding pattern 12, the absorption coefficient for the X-rays is small and therefore almost attenuated. Transparent without. In this way, a contrast in X-ray intensity corresponding to the shielding pattern 12 can be obtained on the upper surface of the substrate 14 to be exposed.

Problems to be Solved by the Invention According to the above conventional configuration, the energy of the absorbed X-rays is converted into thermal energy, and the temperature of the X-ray exposure mask increases during exposure. There is a point at which the expansion occurs, and as a result, the shape of the shielding pattern 12 changes and the positional accuracy of the shielding pattern 12 deteriorates. In addition, in the process of X-ray absorption, photoelectrons and Auger electrons a are generated within the shielding body, and these electrons are shielded by 'X! Since the substrate 14 to be exposed near the bottom of the body is exposed, in order to reduce this exposure (LillQ13 is formed,
There is a problem in that the contrast of the X-ray intensity on the exposed substrate 14 decreases due to radiation absorption.

Therefore, an object of the present invention is to provide an X-ray exposure mask that can solve the above problems.

Means for Solving the Problems In order to solve the above problems, the X-ray exposure mask of the present invention uses an X-ray absorber laminated with an X-ray reflective film as a shield against X-rays. be.

Effect: According to the above configuration, a portion of the X-rays are reflected by the X-ray reflective film, and the remaining X-rays are absorbed by the X-ray absorber.

Therefore, the amount of X-rays absorbed by the mask is reduced, and the temperature rise of the mask itself is suppressed, and the generation of photoelectrons and Auger electrons is also suppressed.

Example Hereinafter, one embodiment of the present invention will be described based on the drawings.

The manufacturing process of an X-ray exposure mask will be explained based on FIGS. 1(a) to 1(e). First, as shown in FIG. 1(a), a film 171.5 to 2.0
A .mu.m silicon nitride thin film 2 is deposited by plasma chemical vapor deposition. Next, on the back side of the silicon substrate 1, a film with a thickness of 0.5 to
A 0.6 μm silicon nitride thin film 3 is deposited by plasma chemical vapor deposition. Next, a W layer 4 with a thickness of 10 IB and a beryllium (Be) layer 5 with a thickness of 25 are deposited by high-speed atomic beam sputtering. With this WNJ4 and 88 layer 5 as one period, this is layered with Wi for 100 periods, and! & Later, a W layer 4 is deposited. These W layer 4 and 88 layer 5 constitute an X-ray reflective film, and this X-ray reflective film has a high reflectance for X-rays. Then, on the surface of the last W layer 4,
Next, as shown in FIG. 1(b), a W layer 6 with a thickness of 0.4 μm as a line absorber is deposited by high-frequency sputtering.
A photoresist pattern 7 is formed on the surface of the silicon nitride film 3 on the back side, and using this as a mask, SFs and CCQ4 are formed.
Next, as shown in FIG. 1(C), after removing the photoresist pattern 7, the silicon nitride thin film 3 is removed using the RIE method using a mixed gas of 1 is removed with a 25% by weight potassium hydroxide aqueous solution at 100''C.Next, as shown in FIG. 1(d), a resist pattern 8 is formed on the surface of the W layer 6 using a light exposure method or an electron beam. It is formed by an exposure method.Chloromethylated polystyrene (CMS) is used as the resist.Then, using this resist pattern 8 as a mask, unnecessary parts of the W layer 4.6 and the 88 layer 5 are coated with SF6 and CC.
It is removed by RIE method using mixed scum of Ω4. and,
Thereafter, as shown in FIG. 1(e), the resist pattern 8 is removed using oxygen plasma.

According to the above-mentioned X-ray exposure mask, about half of the X-rays are reflected by the X-ray reflective film formed by laminating the W layer 4 and the 88 layer 5 in multiple layers, so the amount of X-rays absorbed within the mask is This reduces the temperature rise of the mask itself, thereby reducing changes in the shape of the X-ray shielding pattern and deterioration in position accuracy. In addition, the amount of photoelectrons and Auger electrons generated inside the X-ray shield is reduced, and the effect of these electrons exposing the exposed substrate near the X-ray shield Kinoshita is reduced, allowing the thickness of the protective film to be made thinner than before. It also becomes possible to make the film thinner, and the contrast of the X-ray intensity on the exposed substrate increases.

By the way, in the above embodiment, W is used as the X-ray reflective film.
Although a structure in which layers and Be layers are alternately stacked is used, a structure in which W layers and carbon (C) layers are alternately stacked may also be used.

Effects of the Invention According to the above configuration of the present invention, a part of the X-rays is reflected by the X-ray reflective film, so the amount of X-rays absorbed is reduced and the temperature rise of the mask itself is suppressed. It is possible to prevent the deformation of the X-ray shielding pattern and the deterioration of positional accuracy that had occurred, and the amount of photoelectrons and Auger electrons generated in the X-ray shielding body is also reduced.
It is now possible to make the protective film thinner than before,
The contrast of X-ray intensity on the exposed substrate can be increased.

[Brief explanation of the drawing]

1A to 1E are cross-sectional views showing the manufacturing process of an X-ray exposure mask according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view of a conventional X-ray exposure mask. 1... Silicon substrate, 2, 3... Silicon nitride film, 4
゜6...W layer, 5...Be layer. Agent Yoshihiro Morimoto Figure F (a) (d) (b)
(en(Cnj-・-B8 layer

Claims (1)

[Claims] 1. An X-ray exposure mask using an X-ray absorber laminated with an X-ray reflective film as a shield against X-rays. 2. The X-ray exposure mask according to claim 1, wherein the X-ray reflective film has a structure in which a plurality of types of atomic layers are alternately stacked.