JPH03228310A - Mask for x-ray exposure and manufacture thereof - Google Patents

Abstract

PURPOSE:To reduce the strain on the mask positions without forming a supplementary layer as usual by a method wherein the opposite surface to the surface of an X-ray transmissible thin film substrate in contact with X-ray absorber patterns is processed so that the thickness of said substrate may be differentiated between the X-ray absorber pattern parts and the other parts. CONSTITUTION:Within the title mask for X-ray exposure, the opposite surface to the surface of an X-ray transmissive thin film substrate 2 in contact with X-ray absorber patterns 3 is processed so that the thickness of said substrate 2 may be differentiated between the X-ray absorber pattern parts 3 and the other parts. For example, when the stresses of said substrate 2 and said patterns 3 are tensile stress or compressive stress taking the same direction, the thickness of said substrate 2 on said patterns 3 is reduced, however, when both element 2 and 3 take different directions, the thickness of the X-ray transmissive thin film substrate 2 on the parts excluding the X-ray absorber patterns 3 is reduced.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to the structure of an X-ray exposure mask in semiconductor manufacturing process lathography technology, and in particular to an X-ray exposure mask with small positional distortion of a pattern caused by stress. Related to a mask and its manufacturing method.

[Conventional technology]

The conventional X-ray exposure mask is disclosed in Japanese Patent Application Laid-open No. 63-136620.
As described in the publication, an X-ray absorber pattern was provided on an X-ray transparent thin film substrate whose periphery was fixed with a support frame, and an X-ray transparent thin film supplementary layer was embedded in the gap between the X-ray absorber patterns. . The outline is shown in Fig. 2. That is, support frame 1 and
When an X-ray absorber pattern 3 is formed on a mask blank made of a radiation-transparent thin film 2, the stress of the X-ray absorber pattern expands and contracts the X-ray transparent thin film, causing positional distortion of the pattern. An X-ray transparent thin film supplementary layer 8 having the same stress as that of the absorber pattern is embedded in the gap between the X-ray absorber patterns.

Note that the X-ray transparent thin film substrate has Si, N4. Si
C.

A single layer or a composite layer of BN or the like is used, Au, W, Ta, Mo, etc. are used for the X-ray absorber pattern, and Si3N4. SiO2 is used.

[Problems to be Solved by the Invention] The above-mentioned prior art has a problem when forming the X-ray transparent thin film supplementary layer. That is, after forming an X-ray absorber pattern, microwave electron cyclotron resonance (E
CR, electrocyclotron reas
onance) type plasma CVD method.
After that, the Si, N4, and Sio2 films on the resist are lifted off and removed using a resist stripping solution, thereby forming an X-ray transparent thin film supplementary layer in the gap between the X-ray absorber patterns. However, if the ECR plasma CVD film adheres to the side wall of the resist or the pattern to be removed has a large area, residual portions of the lift-off removal process may occur, leading to frequent defects.

An object of the present invention is to reduce mask position distortion without forming a conventional supplementary layer.

[Means to solve the problem]

In order to achieve the above object, in the present invention, the back surface of an X-ray transparent thin film substrate is processed in accordance with the portion of the X-ray absorber pattern provided on the surface of the X-ray transparent thin film substrate, and the thin film substrate By balancing the stress of the absorber pattern with the stress of the absorber pattern, the positional strain of the absorber pattern is reduced.

[Effect]

As shown in Figure 5, the stress of the X-ray absorber pattern is σΔ,
When the thickness is t^, the stress of the X-ray transparent thin film substrate is σ, and the difference in thickness in the pattern part is Δt, σAt^=σ
By changing the thickness of the X-ray transparent thin film substrate so as to satisfy Δt, the stress between the two is balanced, and the positional strain of the X-ray absorber pattern due to the stress is reduced. For example, if the stress in the X-ray transparent thin film substrate and the X-ray absorber pattern are tensile stress or compressive stress, and have stresses in the same direction, the If the thickness of the radiation-transparent thin film substrate is reduced and the stress directions of the two are different from each other, the X
It is effective to reduce the thickness of the X-ray transparent thin film substrate in areas other than the radiation absorber pattern.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG.

First, a silicon nitride film is deposited to a thickness of 3 μm as an X-ray transparent thin film substrate 2 on the surface of a silicon substrate.
The silicon substrate is etched leaving a portion that will become etched, and then gold is deposited on the silicon nitride film 2 as an electrode layer 4 to a thickness of 0.1 μm by vacuum evaporation, and then on the electrode layer 4. Electron beam resist 5 was applied to a thickness of 1 μm.

Next, electron beam drawing and development are performed to form plating resist 5.
formed a pattern. This state is shown in FIG. 4(A).

The above silicon nitride film was formed by low pressure chemical vapor deposition (LPCVD).
method) using dichlorosilane (S i H, CQ2) and ammonia (NH3) as reaction gases.
using a mixed gas with a relative concentration of 10:1,
When the film formation temperature is 700℃, the stress is 7X10'N
/m2 (tensile) membrane was obtained.

Next, selective gold electrolytic plating is performed on the exposed parts of the electrode layer based on the plating resist pattern to form an X-ray absorber pattern 3 with a thickness of 1 μm, and then the plating resist pattern is replaced with oxygen plasma. It was removed by etching, and the exposed electrode layer was further removed by sputter etching using argon ions. This state is shown in FIG. 4(B). For the above gold plating, Neutronex 309 manufactured by Electroplating Engineers was used as the plating liquid, and the stress was 6 x 10'N at an average current density of 1 mA/cm2.
/m2 (tensile) membrane was obtained.

Next, a negative X-ray resist 7a is applied to a thickness of 0.5 μm on the side opposite to the side on which the X-ray absorber pattern is formed, and then X-ray resist 7a is applied from the side on which the X-ray absorber pattern is formed. Irradiate line 6. This state is shown in FIG. 4(C).

Next, the X-ray resist is developed to obtain an X-ray resist pattern 7b. This state is shown in FIG. 4(D). Next, based on the X-ray resist pattern, the silicon nitride film is etched to a depth of 0.86 μm by parallel plate reactive ion etching using carbon tetrafluoride gas. This state is shown in FIG. 4(E).

Measurement of positional strain was performed under the conditions shown below. That is, X
The line exposure aperture diameter is 4On+n+, and the area is 1 within the aperture diameter.
．． Twenty-five 51 m2 patterns of various shapes were arranged in 5×5 rows so that each pattern was approximately equally spaced, and the spacing between each pattern was measured before and after processing the silicon nitride film. In the case of the above example, before processing the silicon nitride film, the pattern spacing was wider than the design value due to the stress of the gold plating film, and the deviation value (3σ) of the amount of change from the design value was 0.5 μm. , after processing the silicon nitride film, it was less than 0.1 μm.

In addition, in the above embodiment, the plating film stress fluctuates and 2
When the plating film stress becomes as small as 10'N/m2, the processing depth of the silicon nitride film is set to 0.29μm, and when the plating film stress becomes as large as 1x10sN/m2, the processing depth of the silicon nitride film is set to 0.29μm. A similar effect was obtained by setting the thickness to 1.43 μm.

〔Effect of the invention〕

According to the present invention, while the stress of the X-ray absorber pattern tends to expand and contract the X-ray transparent thin film substrate, the X-ray transparent thin film substrate cancels out the stress of the X-ray absorber pattern. By having a stress distribution, the expansion and contraction of the X-ray transparent thin film substrate is suppressed, and the positional distortion of the X-ray absorber pattern is significantly reduced.

[Brief explanation of drawings]

1 and 3 are cross-sectional structural diagrams for explaining the present invention in detail, FIG. 2 is a cross-sectional structural diagram for explaining the prior art,
FIG. 4 is a sectional structural diagram for explaining the present invention in detail, and FIG. 5 is a partial sectional structural diagram for explaining the present invention in detail. ■...Support frame, 2...X-ray transparent thin film substrate, 3...
X-ray absorber pattern, 4...electrode layer, 5...resist pattern for plating, 6...X-ray, 7...xi resist, 8.

Claims (1)

[Claims]1. In the radiation exposure mask, the surface of the X-ray transparent thin film substrate opposite to the surface in contact with the X-ray absorber pattern is processed so that the thickness of the X-ray transparent thin film substrate is equal to the X-ray absorber pattern portion. An X-ray exposure mask characterized by being different in other parts. 2. The X-ray exposure mask according to claim 1, wherein the thickness of the X-ray transparent thin film substrate is thinner in the X-ray absorber pattern portion than in the other portions. . 3. The X-ray exposure mask according to claim 1, wherein the thickness of the X-ray transparent thin film substrate is thicker at the X-ray absorber pattern portion than at other portions. . 4. Forming a desired pattern made of an X-ray absorber material on an X-ray transparent thin film substrate with a uniform thickness that transmits X-rays;
A resist that makes the X-ray sensitive area insolubilized or solubilized is laminated on the X-ray transparent thin film on the side opposite to the patterned surface, and the
After irradiating X-rays from the X-ray absorber pattern side using the ray absorber pattern as a mask, the X-ray photoresist is developed, and the X-ray photoresist pattern is used as a mask to irradiate X-rays.
A method for manufacturing an X-ray exposure mask, which includes dry etching a radiation-transparent thin film substrate to reduce the thickness by a predetermined thickness.