JPH02302020A - X-ray mask and its manufacture - Google Patents

Abstract

PURPOSE:To easily evaluate sensitivity of a resist by a method wherein, after a plurality of resist regions whose thickness is different have been formed on an X-ray absorber, the resist regions and one part of the X-ray absorber directly under the resists are dry-etched. CONSTITUTION:A plurality of X-ray absorbers 2 whose thickness is different are formed on the surface of an X-ray transmitter 1; it is constituted that this transmitter is held on a mask support body 3. When an X-ray mask is arranged on the surface of a water coated with a resist and an X-ray exposure operation and a developing operation are executed, the resist is formed in such a way that its film thickness is different by a difference in film thickness of the individual X-ray absorbers 2. Consequently, a measured result of the film thickness is drawn as a sensitivity curve; alternatively, different kinds of chips between element patterns are exposed by making use of the X-ray mask as a reticle by using an X-ray stepper; thereby, this assembly can be used as a development monitor when the element patterns are developed.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to an X-ray mask used for measuring the sensitivity of an X-ray resist used for X-ray microfabrication in the manufacture of semiconductor integrated devices, or for monitoring development; It relates to its manufacturing method.

(Prior Art) Recently, the miniaturization of semiconductor elements in semiconductor integrated circuits has progressed significantly, and therefore, X-ray phosphorography technology has been attracting attention for pattern formation. On the other hand, various X-ray resists (hereinafter simply referred to as resists) are being developed one after another for X-ray lithography technology, and it is necessary to evaluate their functions as quickly as possible.

Sensitivity and resolution are important functions in resist evaluation. Sensitivity evaluation involves exposing each of multiple wafers coated with resist to X-rays at various times, and forming the development results into a sensitivity curve. I'm going.

However, this method has the disadvantage that a large number of wafers are prepared and each wafer is exposed to different types of light, which takes time. Recently, in order to eliminate this drawback, a method has been developed in which one wafer is exposed to X-rays using an X-ray mask with multiple patterns of different transmittance for the X-ray source, and a sensitivity curve is drawn by exposing one wafer once. is proposed.

(Problems to be Solved by the Invention) However, in the above method, an appropriate means for forming a plurality of patterns having different transmittances has not been solved, and the method currently used is rotation.

In view of the above, it is an object of the present invention to provide an X-ray mask and a method for manufacturing the same, which can easily draw a sensitivity curve of a resist and easily evaluate the sensitivity.

(Means for Solving Problem 11) The present invention achieves the above object by forming a plurality of resist regions with different thicknesses on an IAI absorber, and then
This is achieved by a method of manufacturing an X-ray mask by dry etching a part of the X-ray absorber directly under the resist.

(Function) According to the present invention, an X-ray mask for measuring the exposure sensitivity of an X-ray resist or monitoring the progress of development of an X-ray resist can be manufactured very easily.

(Embodiment) FIG. 1 is a diagram showing an X-ray mask according to a first embodiment of the present invention. Figure (,) is a plan view, and Figure (b) is a cross-sectional view taken along the line A-A'. 1 indicates an X-ray transmitting body, and a plurality of X-ray absorbing bodies 2 with different thicknesses are formed on the upper surface of the body. Then, mask support 3
The configuration is maintained above.

This X-ray mask is used as follows. That is, this X-ray mask is placed on the top surface of the wafer coated with resist, and the
When line exposure and development are performed, the resist film is formed with a different thickness due to the difference in the film thickness of each X-ray absorber 2. Therefore, the measurement result of the film thickness is drawn as a sensitivity curve, or this X-ray absorber 2 is By using a mask as a reticle and exposing different chips between device patterns using an X-ray stepper, it is used as a development monitor during device pattern development.

FIG. 2 is a diagram showing the second embodiment, in which (a) and (b) are shown similarly to FIG. 1, and 4 is an X-ray mask pattern;
Other symbols refer to the same things as in FIG.

This is an area in which a plurality of xg absorbers 2 having different thicknesses are arranged as shown in Fig. 1 in one corner of an area where an x-ray mask pattern 4 of a semiconductor element is formed on an x-ray transparent body 1. . This X-ray mask has the advantage of being very useful as a development monitor for the X-ray mask pattern 4 during development.

FIG. 3 is a process sectional view showing the method for manufacturing the above-mentioned X-ray mask, in which 5 is a resist film, and other symbols refer to the previous explanation.

To manufacture the X-ray mask of the present invention, first, a silicon nitride (SiN) film is formed to a thickness of 2μ as the X-ray transmitter 1 on the mask support 3, which is usually constituted by a silicon substrate. Tungsten (W) as X-ray absorber 2 on top
The film is formed with a thickness of 0.6 μm. For example, chloromethylated polystyrene (CM
S) was applied to a thickness of 0.6 μl, pre-baked at 110°C for 520 minutes, and then the size was 50 μm x 50 μm, and the electron beam was changed numerically from 1 μC/cd to 50 μC/−. 100 squares are drawn (FIG. 3(a)). It should be noted that only 11 representative exposures A, B, C, D, and E having different exposure amounts are shown in FIG.

Next, a pattern is formed by developing for 1 minute using a solution of isoamyl acetate and ethyl cellosolve in a ratio of 1:3 as a developer. At this time, the resist completely remains in the areas where the exposure amount is large, the resist remains in the areas where the exposure amount is small, depending on the exposure amount, and the resist is completely removed from the unexposed areas ((b) in the same figure). ', B', C', D', E
', are exposures A, B, C, D, and E with different exposure amounts, respectively.
The remaining resist area corresponding to .

Next, using a parallel plate type etching device, SF was used as the etching gas, and the high frequency power density was 0.3/-1.
The tungsten film X-ray absorber 2 is etched under a pressure of 15 mTorr. If the etching time is set so that the etching of the tungsten film of the X-ray absorber 2 is completed when the resist region A' with the maximum remaining film thickness is removed by etching, the etching time will be set according to the remaining film thickness of the resist. As the X-ray absorber 2 having different thicknesses, tungsten films are formed as shown in FIG. 3(Q). A', B',
C''.

D″ and E″ are the remaining tungsten films, and correspond to the remaining resists A′, B′, D′, D′, and E′, respectively. Thereafter, the central portion of the silicon substrate of the mask support 3 is removed by etching from the back side, thereby completing an X-ray mask as shown in FIG. 3(d). In addition, the X-ray absorber 2
When dry etching the tungsten film, by making the etching speed equal to that of the resist, there is an advantage that the film thickness of the resist can be directly transferred to the tungsten film of the X-ray absorber 2.

(Effects of the Invention) As is clear from the above detailed description, the present invention allows an X-ray mask in which the X-ray exposure amount changes in fine steps to be easily constructed, and the constructed X-ray mask is It can be used for resist sensitivity evaluation or as a development monitor during resist development.

It can be used to form X-ray patterns with the recent miniaturization of semiconductor devices, and can exhibit extremely large effects.

[Brief explanation of drawings]

1 and 2 are a plan view and a sectional view showing the first and second embodiments of the present invention, respectively, and FIG. 3 is a xi
It is a sectional view of the manufacturing process of a mask. 1... X-ray transmitting body, 2... X-ray absorbing body, 3...
・Mask support, 4... X-ray mask pattern,
5...Resist film. Patent applicant Matsushita Electronics Co., Ltd. Figure 1 (a) (b) Figure 2 (a) (b)

Claims (4)

[Claims] (1) Using an X-ray transmitting body such as a semiconductor substrate as a mask substrate,
An X-ray mask characterized in that a plurality of X-ray absorbers having different X-ray transmittances are formed on its surface. (2) The X-ray mask according to claim 1, wherein the plurality of X-ray absorbers having different transmittances are formed on the same substrate as the X-ray pattern of the element. (3) An X-ray method comprising the step of forming a plurality of resist regions having different thicknesses on the X-ray absorber, and then dry etching the resist regions and a part of the X-ray absorber directly under the resist. How to make line masks. (4) The method for manufacturing an X-ray mask according to claim (3), characterized in that the dry etching is carried out at the same etching rate for the resist region and the X-ray absorber.