JPH01263599A - Manufacture of semiconductor - Google Patents

Abstract

PURPOSE:To enable a precise printing of a very fine mask pattern on a semiconductor wafer, by obtaining an X-ray highly parallel and of single wave length utilizing two times Bragg's reflections in an optical system of an X-ray stepper. CONSTITUTION:A parallel flat plates and double crystals monochrometer 1-1 has double reflection surfaces 1-4 and 1-4 which are cut out from a single crystal, and these reflection surfaces face parallelly each other and also are placed at a Bragg's reflection angle thetaB to an incident X-ray 1-2. The Bragg's reflection angle thetaB is calculated from a distance between the two crystal surfaces and wave lengths of incident and emitting X-rays. In this way, the incident X-ray 1-2 is emitted as a highly parallel monochrome X-ray 1-3 after repeating the Bragg's reflections twice, and because the directions of incident and emitting rays are the same, a mask at the tip end of an optical system can be easily prepared.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an X-ray stepper, and particularly to its optical system.

[Conventional technology]

Conventionally, in the optical system of steppers, not only X-rays but also
Also in systems that use visible light and ultraviolet light.

Obtaining highly parallel light at a constant wavelength has become an important issue.The optical system of a stepper that uses X-rays, which is the subject of the present invention, utilizes one Bragg reflection from a single crystal monochromator. This method is mainly used.

[Problem to be solved by the invention]

In the method using single reflection described above, in addition to the desired Bragg reflection, there is a possibility that some X-rays from the X-ray source with a different incident direction and wavelength will be reflected, and Bragg reflection may also occur. Since the light itself usually has a certain angular width, as represented by the half-width, it is difficult to obtain monochromatic light with sufficiently high parallelism. Because the reflected light of is shifted by twice the Bragg reflection angle used with respect to the incident light.

It is difficult to set up the mask and wafer beyond the optical system.

An object of the present invention is to provide a semiconductor manufacturing apparatus that solves the above problems.

[Differences between the invention and the prior art]

The present invention differs from the above-described conventional optical system that uses one reflection in that it uses multiple reflections, mainly two reflections. In addition, as a monochromator for double (or multiple) reflections, a monochromator with two parallel and opposing surfaces made of a single crystal is used instead of using two (or many) separate crystals. The difference is that it is used. Furthermore, even under multiple reflection conditions, multiple monochromators are not required; as long as the size of the monochromator of the present invention and the Bragg reflection conditions are appropriately set, multiple reflections can be achieved with just one monochromator. The difference is that it is possible to perform

[Means to solve the problem]

In order to achieve the above object, the semiconductor manufacturing apparatus of the present invention includes two parallel plate type crystals cut from a single crystal and having X-ray reflecting surfaces parallel to each other and facing each other in the optical system of the stepper. It has a monochromator.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a schematic diagram of an embodiment of the invention. In this drawing, the optical system is shown, and the X-ray source system and the stepper body beyond the optical system are omitted.

Reference numeral 1-1 is a parallel plate monochromator having reflecting surfaces (hlQ) 1-4, 1-4 cut out from a single crystal and facing each other parallel to each other. This monochromator-1-
1 is cut out from a single silicon ingot, for example. Because two reflective surfaces are cut out from a single crystal, the spacing between the crystal planes is the same for the two reflective surfaces, and unlike the case where two crystals are used to reflect twice, it is easy to install an optical system. There are also benefits. Reflective surface 1-
4 is preferably a surface with a low-order direction such as a (111) or (100) surface in order to obtain reflection intensity and ease of cutting out.

Reference numeral 1-2 is an incident X-ray, and the monochromator 1-1 is set to a condition that Bragg-reflects the light of the desired wavelength of the incident XB1-2. Bragg reflection angle OB is 0B=s
in (λ/2Dbkz)-''. Here, Dhk& is the distance between the (hkQ) planes of the monochromator crystal, and the tip indicates the wavelength of the input and output X-rays. Monochromator-1
-1 X-ray 1 reflected for the first time on one reflective surface 1-4
-2 undergoes a second Bragg reflection on the opposite reflecting surface 1-4, and the output X-ray 1-3 becomes a monochromatic X-ray with high parallelism.
is obtained. The reflection may occur two or more times. In the case of an even number of reflections, the directions of the incident light and the incident light are the same, which has the advantage of making it easier to set the mask at the end of the optical system.

〔Effect of the invention〕

As described above, the present invention uses two Bragg reflections in the optical system of the X-ray stepper, thereby making it possible to obtain highly parallel X-rays of a single wavelength.

Obtaining highly parallel, single-wavelength X-rays is essential for accurately burning fine mask patterns onto semiconductor wafers. Moreover, the monochromator of the present invention
is obtained by cutting out two reflective surfaces from a single crystal.
The Bragg reflection conditions on the two reflecting surfaces are the same, and the optical system can be installed more easily than when two crystals are used separately. Furthermore, as in the embodiments of the present invention, by using an even number of Bragg reflections, it is possible to obtain outgoing light in the same direction as the incident direction. This means that
Compared to a normal system that uses one-time reflection, this has the effect of making it easier to set the position of the optical system and the mask beyond it.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an embodiment of the present invention. 1-1...Parallel plate monochromator with reflective surface (hkQ)-1-2...Incoming X-ray 1-3...Output xa1-4 from the monochromator...
・Reflection surface of (hkQ) direction

Claims (1)

[Claims] (1) A semiconductor manufacturing apparatus characterized in that the optical system of the stepper includes a parallel plate type two-crystal monochromator cut from a single crystal and whose X-ray reflecting surfaces are parallel to each other and face each other.