JPH04206709A - Alignment mask and x-ray aligner - Google Patents

Abstract

PURPOSE:To facilitate manufacture and handling of an alignment mask and realize pattern transcription with high accuracy by a method wherein a required pattern is formed of material having a crystal structure which facilitates Bragg reflection on a substrate made of material which absorbs an X-ray, etc. CONSTITUTION:A required pattern 14 is formed of material having a crystal structure which facilitates Bragg reflection on a substrate 13 made of material which absorbs an X-ray to compose an alignment mask 11 or 21. Or, an X-ray irradiation means 10 or 21 which applies an X-ray and a structure wherein the required pattern 14 is formed of material which facilitates Bragg reflection on the substrate 13 made of material which absorbs or transmits an X-ray are provided and the alignment mask 11 or 22 which is so arranged as to have an X-ray from the X-ray irradiation means 10 or 21 applied to the mask 11 or 22 from a slant direction and a holding table 27 which holds a substrate 12 or 25 to be exposed at a position to which an X-ray reflected by the alignment mask 11 or 22 is applied are provided to constitute an X-ray aligner 20.

Description

[Detailed Description of the Invention] [Summary] The present invention relates to an exposure mask and an X-ray exposure device, and in particular to an exposure mask and an X-ray exposure device that can form fine patterns, making it easier to manufacture and handle the mask. The aim is to achieve high-precision pattern transfer by forming a predetermined pattern on a substrate made of a material that absorbs X-rays using a material with a crystal structure that can cause Bragg reflection.

It also has a structure in which a predetermined pattern is formed on an X-ray irradiation means that irradiates X-rays and a substrate made of a material that absorbs X-rays, using a substance with a crystal structure that can cause Bragg reflection. an exposure mask arranged so that X-rays are obliquely irradiated from an X-ray irradiation means; and a holding base that holds a substrate to be exposed at a position where the X-rays reflected by the exposure mask are irradiated. The configuration includes the following.

[Industrial application field]

The present invention relates to an exposure mask and an X-ray exposure apparatus, and more particularly to an exposure mask and an X-ray exposure apparatus that can form fine patterns.

In recent years, as the degree of integration of semiconductor devices has improved, requirements for fine pattern lithography technology have become increasingly strict.

For example, when manufacturing 64M DRAM (64 Mega Dynamic Random Access Memory), 0.
It is said that it is necessary to form a micro pattern of 3 μm.

Therefore, there is a need for an exposure mask or an X-ray exposure apparatus that can achieve high pattern processing accuracy.

[Conventional technology]

FIG. 5 shows a schematic configuration diagram of a conventional X-ray exposure apparatus 1. In the same figure, 2 is an X-ray irradiation device, 3 is a mask,
4 indicates a wafer.

The X-ray irradiation device 2 is configured to irradiate X-rays with a wavelength of 0.4 to 1 nm, for example.

In addition, the mask 3 includes a support film 5 having good X-ray transparency and an X-ray transmittance.
The absorber 6 has a high absorption rate for lines. This absorber 6 is formed on the support film 5 in a shape corresponding to a predetermined pattern to be formed on the wafer 4. Furthermore, a resist 7 is applied onto the wafer 4.

X-rays emitted from the X-ray irradiation device 2 are transmitted through a mask 3 and irradiated onto a wafer 4, whereby a predetermined pattern formed on the mask 3 is transferred onto the wafer 4.

[Invention or problem to be solved]

However, in the past, since the mask 3 was a transmission type mask, it was necessary to reduce the thickness of the support film 5 in order to improve the efficiency of X-ray irradiation. Further, the absorber 6 must be formed in a predetermined pattern with high precision on this thin support film 5. For this reason, the manufacturing and handling of the mask 3 is extremely troublesome and difficult.

Furthermore, in the past, a proximity pattern transfer method was adopted in which a predetermined pattern (mask pattern) formed on the mask 3 was projected on a one-to-one basis without being reduced. It was necessary to form the .

Therefore, this also poses a problem in that manufacturing of the mask 3 becomes difficult.

The present invention has been made in view of the above points, and it is an object of the present invention to provide an exposure mask and an X-ray exposure apparatus that can facilitate the manufacture and handling of the mask and can realize highly accurate pattern transfer. shall be.

[Means to solve the problem]

In order to solve the above problems, in the present invention, the exposure mask has a structure in which a predetermined pattern is formed on a substrate made of a material that absorbs X-rays, using a substance that causes Bragg reflection and has a vine crystal structure. It is characterized by:

In addition, an X-ray exposure device is equipped with an X-ray irradiation means for irradiating X-rays, and a substrate made of a material that absorbs or transmits X-rays, on which a predetermined pattern is formed using a substance with a crystal structure capable of causing Bragg reflection. an exposure mask having a structure and arranged so that X-rays are obliquely irradiated from the X-ray irradiation means; and a substrate to be exposed at a position where the X-rays reflected by the exposure mask are irradiated. The present invention is characterized in that it has a structure in which a holding base for holding the object is provided.

[Effect] FIG. 1 is a diagram for explaining the present invention in detail.

In the figure, 10 is an X-ray irradiation device, 11 is an exposure mask, and 12 is a wafer. The X-ray irradiation device 10 is
The exposure mask 11 is configured to be irradiated with X-rays from an oblique direction. The exposure mask 11 has a predetermined pattern 14 formed on a substrate 13 made of a material that absorbs X-rays and made of a substance having a crystal structure capable of causing Bragg reflection.

The X-ray irradiation device 10 irradiates X-rays toward the exposure mask 11 . Among the X-rays irradiated to the exposure mask 11, the substrate 1
The X-rays irradiated to the exposed portion 3 are absorbed by the substrate 13 and are not reflected. Further, the X-rays irradiated to the area where the pattern 14 is formed are Bragg-reflected and irradiated onto the wafer 12. Therefore, the predetermined pattern 1
4 is transferred onto the wafer 12.

Also, the size of the pattern 14 (L in the figure).

If we pay attention to the size of the wafer pattern formed on the wafer 12 (indicated by L2.L2° in the figure), the exposure mask 1.1 has a reflective mask, and Since the line is irradiated obliquely to this reflective exposure mask 11, the line is L.

>L2. Ll">L2". That is, the configuration of the present invention is a reduction projection exposure, and therefore the pattern 14 formed on the reflective exposure mask 11 can be formed larger than the wafer pattern.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 2 is a schematic configuration diagram showing an X-ray exposure apparatus 20 which is an embodiment of the present invention. In the figure, 2] is an X-ray irradiation device, for example, a wavelength of 0.1-1. This is a device that generates Onm soft X-rays. The exposure mask 22 is irradiated with X-rays emitted from this X-ray irradiation device 21 . At this time, the exposure mask 22 is configured to be irradiated with the X-rays from an oblique direction. Moreover, this irradiation angle (indicated by θ0 in the figure) is configured to be adjustable, so that any irradiation angle θ can be set. The exposure mask 22 can be irradiated with X-rays.

The exposure mask 22 has an X
The structure is such that a predetermined pattern 24 is formed on a substrate 23 made of a material that absorbs radiation, and is made of a substance having a crystal structure capable of causing Bragg reflection.

As the material of the substrate 23, amorphous quartz or the like can be considered. Furthermore, a material that absorbs X-rays also means a material that does not reflect X-rays, and from this point of view, organic materials such as polyimide and inorganic materials such as silicon that transmit X-rays can also be used as materials for the substrate 23. obtain.

On the other hand, the material of the pattern 24 corresponds to the wavelength and irradiation angle θ of the X-rays emitted from the X-ray irradiation device 21. Determined by

That is, the material of the pattern 24 must be capable of Bragg reflection of the irradiated X-rays.

Here, Bragg reflection (also called Bragg diffraction) is
When X-rays are incident on a reflective surface (diffraction surface) at a predetermined angle that satisfies the Bragg condition, the reflected light beams reflected from each stacked crystal lattice plane intensify each other in the same phase in a specific direction, resulting in strong diffraction. A phenomenon that generates waves. The Bragg condition is a condition that satisfies the following equation, where d is the distance between gratings, λ is the wavelength of the X-ray, θ is the angle between the grating surface and the incident X-ray, and n is an integer.

2dsinθ=nλ Material of pattern 24 and above-mentioned irradiation angle θ. is selected to satisfy this Bragg condition.

Pattern 2 made of material that satisfies the above Bragg conditions
4 is formed on the substrate 23 in a predetermined pattern shape.

When forming this pattern 24, as explained using FIG. The shape of the pattern 24 formed thereon can be increased. Therefore, the pattern 24 can be formed easily.

Further, the exposure mask 22 is configured to transfer a predetermined mask pattern onto the wafer 25 by reflecting the X-rays emitted from the X-ray irradiation device 21 instead of transmitting them. Therefore, when selecting the board 23,
There is no need to take into consideration the transmission of lines, and therefore the thickness of the substrate 23 can be increased. Thereby, the mechanical strength of the exposure mask 22 can be improved, and the manufacturing and handling of the exposure mask 22 can be facilitated.

The explanation will be given by returning to FIG. 2 again. The X-rays reflected by the exposure mask 22 are subsequently incident on a reflecting mirror 26, and the traveling direction of the X-rays is changed. The reflecting mirror 26 is configured to reflect X-rays by forming a material that satisfies the Bragg condition on the front surface on a substrate that is not easily degraded by X-rays.

The direction of the X-rays converted by the reflecting mirror 26 is reflected from the X-ray irradiation device 21 to the exposure mask 22, and
The direction is selected to intersect with the plane including the optical axis of the X-rays up to . That is, the X-rays that have traveled in a plane until reaching the reflecting mirror 26 are reflected three-dimensionally downward by the reflecting mirror 26.

The wafer 25 is disposed at a position in the downward direction in the traveling direction of the reflected X-rays. This Ueno A25 is placed on and held on the holding base 27. A resist that is hardened by X-rays is coated on the surface of the wafer 25, and by irradiating the wafer X25 with the X-rays reflected by the exposure mask 22 and the reflecting mirror 26, the surface of the exposure mask 22 is coated. A predetermined mask pattern formed by the pattern 14 is transferred onto the wafer 25.

Here, how the shape of the pattern 14 formed on the exposure mask 22 is reduced when X-rays are reflected by the exposure mask 22 and the reflecting mirror 26 will be explained using FIG. 4.

FIG. 4(A) shows the shape of the pattern 14 before being reduced. This embodiment will be explained using a rectangular pattern as shown in the figure.

For convenience of explanation, directions on the surface of the exposure mask 22 are expressed using X and Y shown by arrows in FIGS. 2 and 4.

FIG. 4(B) shows the reduced pattern after being reflected by the exposure mask 22. When reflected by a planar surface, reduction occurs in one direction and not in the other direction. As shown in FIG. 2, when reflected by the exposure mask 22, either reduction in the X direction is performed or no reduction in the X direction is performed. Therefore, the reduced pattern after being reflected by the exposure mask 22 has a pattern shape that is reduced only in the X direction, as shown in FIG. 4(B).

FIG. 4(C) shows a reduced pattern after the X-rays reflected by the exposure mask 22 are further reflected by the reflecting mirror 26. As described above, the reflecting mirror 26 three-dimensionally reflects the X-rays traveling in a plane downward, so that reduction in the X direction can be achieved. Therefore,
The reduced pattern after being reflected by the reflecting mirror 26 is shown in Figure 4 (C
), the wafer pattern is reduced in each of the X and Y directions, and a wafer pattern having a predetermined reduction ratio with respect to the mask pattern shown in FIG. 4(A) is formed on the wafer 25. be able to.

In the above-mentioned embodiment, the configuration of the reflecting mirror 26 is shown in which a material that satisfies the Bragg condition is disposed on the substrate, but the structure of the reflecting mirror is not limited to this, and may reflect X-rays. Other configurations may be used as long as they are vine configurations.

Further, in the above embodiment, the exposure mask 22 and the reflecting mirror 26
For example, by making the exposure mask spherical (concave spherical), the exposure mask alone can reduce the size in the X and Y directions. It is also possible to adopt a configuration in which the reduction is performed by

〔Effect of the invention〕

As described above, according to the present invention, since the exposure mask and pattern can be formed in a large size due to reduced projection, the exposure mask can be manufactured easily. Further, since the mask pattern is transferred to the substrate by reflection, the thickness of the exposure mask can be increased, and the mechanical strength is improved, making it easier to handle the exposure mask.

[Brief explanation of the drawing]

Fig. 1 is a diagram for explaining the present invention in detail, Fig. 2 is a schematic configuration diagram showing an X-ray exposure apparatus which is an embodiment of the invention, and Fig. 3 is an exposure diagram which is an embodiment of the invention. FIG. 4 is a diagram for explaining how a pattern is reduced. FIG. 5 is a schematic configuration diagram showing an example of a conventional X-ray exposure apparatus. In the figure, 10.20 is an X-ray exposure device, 11.22 is an exposure mask, 12.25 is a wafer, 13.23 is a substrate, 24.24 is a pattern, 20 is an X-ray exposure device, 26 is a reflecting mirror, 27 indicates a holding base. Patent Applicant: Fujitsu Ltd. Detailed Explanation of the Present Invention Figure 1 shows an exposure mask which is an embodiment of the present invention Figure 3 (C) Explains how a pattern is reduced Diagram for Figure 4

Claims (1)

[Claims] (1) On a substrate (13) made of a material that absorbs X-rays,
An exposure mask characterized by forming a predetermined pattern (14) from a substance having a crystal structure capable of causing Bragg reflection. (2) A predetermined pattern is formed on the X-ray irradiation means (10, 21) that irradiates X-rays and the substrate (13) made of a material that absorbs or transmits X-rays using a substance having a crystal structure that can cause Bragg reflection. an exposure mask (11, 22) having a structure in which the X-ray irradiation means is irradiated with X-rays obliquely; 22) A holding base (27) that holds a substrate to be exposed (12, 25) at a position to be irradiated with X-rays reflected by the X-ray exposure apparatus. (3) between the exposure mask (22) and the holding base (27);
It is characterized by providing an X-ray reflection mechanism (26) that further reflects the X-rays reflected by the exposure mask (22) and changes the traveling direction of the X-rays reflected by the exposure mask (22). The X-ray exposure apparatus according to claim 2.