JPH02129910A - Mask for x-ray exposure - Google Patents

Abstract

PURPOSE:To improve warp of a frame by installing a ring-shaped plate which is formed of a member whose thermal expansion coefficient is larger than that of Si to the rear side of an Si frame at a temperature higher than one used at the time of X-ray exposure. CONSTITUTION:A central section of a film 3 on a lower side is removed by etching to form an X-ray exposure area 4. This is put in a high temperature bath and a ring-shaped plate 7 which is formed by a member such as Ti, Al whose thermal expansion coefficient is larger than that of Si is mounted to an outer side of the remaining film 3 on the lower side. That is, the ring-shaped plate 7 which is formed by a member whose thermal coefficient is larger than that of Si is mounted to a rear side of a frame 5 of Si at a temperature higher than an ordinary temperature; therefore, the plate 7 tends to shrink at an ordinary temperature, thus acting to restore warp of a mask. Warp of a mask can be improved in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an improvement of an X-ray exposure mask used in manufacturing semiconductor devices.

[Conventional technology]

FIG. 2 is an explanatory diagram showing a conventional X-ray exposure mask, and sequentially shows configuration diagrams along the manufacturing process. First, as shown in ■, a Si wafer (1
A film of SiN or BN (23(3)) is formed to a thickness of about 2 μm on both sides of the film by the reduced pressure C method or the like.

Next, as shown in @, the central part of the film (3) on the lower surface is removed by etching, and the exposure area (4) for X-ray exposure is removed.
form. Thereafter, etching is performed using an aqueous KOH solution. In this case, the central portion of the Si wafer (1) is removed using the film (3) remaining on the bottom surface as a mask and shaped into an annular frame (5), while the film (21) on the top surface is not removed. The state shown in C) is reached, and an X-ray transparent film is formed.

By the way, as will be described later, the film +21 (31) is formed to create a tensile internal stress to cause positional distortion of the absorber pattern when the outer absorber pattern is formed. As shown, the S1 wafer (1
) is removed, warping occurs as shown in 06ζ due to the tension of the film (2) on the top surface.

It should be noted that an absorber pattern (
6) An exposure mask is constructed by attaching the mask.

[Problem to be solved by the invention]

The conventional X-ray exposure mask is constructed as described above, and the
Since the structure is such that a membrane with tensile stress is stretched on one side of the frame (5), the stress of the membrane causes the stress in Figure 2 (
As shown in Q, warping occurs toward the film side, resulting in a problem that high-precision transfer and alignment precision of pattern dimensions and pattern placement deteriorates.

This invention was made to solve the above-mentioned problems, and aims to provide an X-ray exposure mask that improves the warping of the frame.

[Means to solve the problem]

The X-ray exposure mask according to the present invention has a ring-shaped plate formed of a material having a larger coefficient of thermal expansion than Si on the back side of a Si frame at a temperature higher than the operating temperature (room temperature) during X-ray exposure. It was designed to be worn under the

[Effect]

According to this invention, a ring-shaped plate made of a material having a larger coefficient of thermal expansion than Sj is attached to the back side of the Si frame at a temperature higher than room temperature, so that the plate does not work at room temperature. The mask tends to contract, and this acts in the direction of reversing the warpage of the mask as described above, thereby improving the warpage of the mask.

[Embodiments of the invention]

In the following, one embodiment of the present invention will be described with reference to FIG.

FIG. 1 is a schematic diagram showing the manufacturing process of the embodiment, in which parts corresponding to the conventional one are given the same reference numerals. 1st
Figures (4) and (2) are the same steps as (b) and (b) in Figure 2, so their explanation will be omitted.

Thereafter, the product in the state shown in (6) is placed in a high-temperature bath G, and a ring-shaped material is formed on the outer surface of the film (3) remaining on the bottom surface of a material having a larger coefficient of thermal expansion than St, such as Ti, A/, etc. Attach the plate (7).

When the temperature is returned to room temperature after the plate (7) is attached, the plate (7) tends to shrink more than the Si, so it warps in a convex shape as shown in (C). In this state, it is immersed in an aqueous KOH solution to perform etching. In this case, the remaining film (3
) serves as a mask, the central portion of the Si wafer (1) is removed, and the frame is shaped into a ring-shaped frame (5 mm) as shown in (2), which is the same as in the conventional method.

Also, at this time, due to the tensile stress of the upper film (2), the second
It is the same as in the conventional system that a force that causes Iζ warps as shown in Figure 9 acts, but since this force acts in the opposite direction to the force that acts in the process Q in Figure 1, both forces If Gζ is balanced, the warpage of the mask can be eliminated or significantly improved, as shown in FIG. 1 (2).

In this state (8) cloudy, the upper film (2) is covered with A.
u.

A mask is completed by attaching an absorber pattern (6) such as W.

In the embodiments described below, Ti and Al were cited as examples of materials constituting the ring-shaped plate (7), but glass materials with a larger coefficient of thermal expansion than Si, ceramic materials such as BN and SfC may also be used. Alternatively, we can expect similar effects from carbon-based materials.

〔Effect of the invention〕

As described above, according to the present invention, the warpage caused by the X-ray transparent membrane attached to one side of the NSI frame is offset by the contraction force of the ring-shaped plate attached to the other side of the frame. It is possible to almost eliminate warping of the mask, and it is possible to perform highly accurate transfer and alignment.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing the manufacturing process of an embodiment of the present invention;
FIG. 2 is an explanatory diagram showing the structure of a conventional X-ray exposure mask along the manufacturing process. In the figure, (1) is a Si wafer, +21 (3) is a film,
(4) is an exposure area, (5) is a frame, (6) is an absorber pattern, and (7) is a ring-shaped temporary. In addition, in the figures, the same reference numerals indicate the same or corresponding parts. Agent Patent Attorney Masuo Oiwa Figure 2

Claims (1)

[Claims] An X-ray transparent membrane was attached to one side of the silicone frame, and a ring-shaped plate made of a material with a larger coefficient of thermal expansion than silicon was attached to the other side, so that the plate could shrink at room temperature. An X-ray exposure mask characterized by