JP2002311216A - Production method for reflection mirror or reflection type illuminator or semiconductor exposing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To firstly provide a production method, with which a multi-light source forming reflection mirror having a reflection plane shape as designed can be produced with high yield, and further to secondly provide a semiconductor exposing device, with which throughput is more improved. SOLUTION: In the production method for reflection mirror for forming a plurality of elementary reflection planes in which one part of a prescribed curved surface is made into plane shape, this method is composed of a process for working so that an outer form or inner diameter has a prescribed curvature radius, a process for cutting a member which is worked into prescribed curvature radius, into prescribed size and a process for locating the member cut in the prescribed size at a prescribed position.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a reflecting mirror and a semiconductor manufacturing apparatus, and more particularly to a reflecting mirror constituted by arranging a plurality of minute element reflecting surfaces at predetermined positions. The present invention relates to a method of manufacturing a semiconductor device, a reflection type illumination device, and a semiconductor exposure apparatus using the illumination device.

[0002]

2. Description of the Related Art At present, in the manufacture of semiconductor devices such as DRAMs and MCPs, development research for narrowing the minimum line width is actively conducted, and the design rule is 0.13 μm.
(4G DRAM equivalent), 0.1μm (16G DRA
M), and various technologies have been developed for realizing 0.07 μm (corresponding to 32G DRAM).

[0003] What is inseparably related to the problem of the minimum line width is a light diffraction phenomenon that occurs during exposure.
This is the biggest problem when realizing the minimum line width that requires the blur of the image and the focal point due to this. In order to suppress the effect of this diffraction phenomenon, the numerical aperture of the exposure optical system (NA: Numerical
It is necessary to increase the aperture), and the development of an optical system with a large aperture and a short wavelength is the point of development.

However, as the wavelength of light becomes shorter,
When the thickness is less than 200 nm, an optical material that is easy to process and has little light absorption cannot be found. Therefore, a projection optical system using a reflection optical system has been developed by abandoning the transmission optical system, and has achieved considerable results. Among them, a combination of a plurality of reflecting mirrors realizes an arc-shaped optical field of view (area that can be used as an exposure area) for soft X-rays, and synchronizes the mask and wafer with each other at the relative speed of the projection reduction ratio. There is a method in which the entire chip is exposed by moving the chip. (For example, Koichiro Hoh and Hi
roshi Tanino; “Feasibility Study on the Extreme UV
/ Soft X-ray Projection-type Lithography ”, Bulleti
n of the Electrontechnical Laboratory Vol. 49, No.
12, 983-990, 1985. This document is hereinafter referred to as Reference Document 1.)

[0005] By the way, the so-called throughput is an important factor for the above-mentioned semiconductor device manufacturing along with the minimum line width. Factors involved in this throughput include the light emission intensity of the light source, the efficiency of the illumination system, the reflectance of the reflector used in the reflection system, and the sensitivity of the photosensitive material / resist on the wafer.

At present, light sources include ArF lasers and F
There are synchrotron radiation light and laser plasma light as light sources of _two lasers and short wavelength light. Also, with respect to a reflector for reflecting such light, development of a multilayer reflector has been carried out at a rapid pace so as to obtain a high reflectance (for details, refer to the above-mentioned reference 1 and Andrew M. Hawryluk). et
al; “Soft x-ray beamsplitters and highly dispersi
ve multilayer mirrors for use as soft x-ray laser
cavity component ”, SPIE Vol. 688 Multilayer Stru
cture and Laboratory X-ray Laser Research (1986)
P.81-90 and JP-A-63-31640).

Now, regarding a semiconductor exposure apparatus,
In this semiconductor exposure apparatus, an illumination optical system for uniformly illuminating the original regardless of the light amount distribution of the light source has been developed in order to uniformly illuminate the original without unevenness. What is required for this illumination optical system is uniform illumination and aperture.
For example, Japanese Patent Application Laid-Open No. 60-232552 proposes a technique for a rectangular illumination area. However, the semiconductor exposure apparatus includes a projection optical system that forms a pattern of an original on a wafer, and when the field of view of the projection optical system is arc-shaped, light utilization efficiency is poor in a rectangular illumination field, Inevitably, the exposure time could not be reduced, and the throughput did not increase.

Recently, as a method of solving this problem, a method of setting an illumination field according to an optical field of a projection optical system and condensing light from a light source in the illumination field is disclosed in, for example, 70058 “X-ray reduction projection exposure apparatus and semiconductor device manufacturing apparatus using the same” has been proposed. In this case, a cylindrical convex semi-cylindrical integrator having a cylindrical shape shown in FIG. 3 is used as an illumination optical system. The reflective convex semi-cylindrical integrator is a total reflection mirror having a reflective surface having a shape in which a large number of minute convex semi-cylindrical surfaces are arranged one-dimensionally. Further, instead of the reflective convex semi-cylindrical integrator, a reflective concave semi-cylindrical integrator as shown in FIG. 4 can be used.

[0009]

By the way, the above-mentioned reflecting mirror is usually manufactured by cutting a single substrate as a workpiece using a cutting machine equipped with a ball end mill. The ball end mill has a shape as shown in FIG. 5 (a). By controlling the position of the ball end mill three-dimensionally with respect to the workpiece, it is possible to process various surfaces as shown in FIG. 5 (b). is there.

However, when the reflecting surface shape shown in FIG. 3 is formed from one aluminum substrate and actually illuminated using the completed multi-light source forming reflecting mirror, an integrator having an expected good reflection efficiency is obtained. Was not formed, and a high throughput was not obtained in a semiconductor exposure apparatus using such an integrator.

Therefore, when the cause was investigated, FIG.
As shown in (1), the convex shape and the convex shape are adjacent to each other, and there is a processing residue in a valley portion, and it has been found that the influence of this portion is main. This processing residue is due to the shaft radius of the ball end mill.

Accordingly, the present invention has been devised in order to solve such a problem, and a first object of the present invention is to provide a manufacturing method capable of manufacturing a multi-light source forming mirror having a reflecting surface shape as designed with a high yield. A second object is to obtain a semiconductor exposure apparatus with higher throughput.

[0013]

In order to achieve the above object, there is provided a method for manufacturing a reflecting mirror in which a plurality of element reflecting surfaces each having a part of a predetermined curved surface are formed in a surface shape, wherein an outer shape or an inner diameter is predetermined. Processing to a radius of curvature, and cutting the member processed to the predetermined radius of curvature to a predetermined size,
Arranging the member cut to the predetermined size at a predetermined position.

Next, the present invention will be described in more detail by way of an embodiment. However, the present invention is not limited to only those described in the embodiments of the invention.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, as an embodiment of the present invention,
A polyhedral mirror, which is a reflective integrator used in the projection exposure apparatus shown in FIG. 2, will be described. This polygon mirror sets the illumination field according to the optical field of the projection optical system, thereby increasing illumination efficiency and solving the problem of throughput.

FIG. 2 is a schematic diagram of a projection exposure apparatus according to an embodiment of the present invention. In this projection exposure apparatus, a light source 1, a polygon mirror 2, a condenser optical element 3, a reflector 4, a mask 5, a mask stage 5s, a projection optical system 6, a wafer 7, a wafer stage 7s , A mask stage controller 8 and a wafer stage controller 9.

Light emitted from a light source 1 is incident on a polygon mirror 2 formed by using the manufacturing method of the present invention. The light reflected by the polygon mirror 2 illuminates the mask 5 held on the mask stage 5s via the condenser optical element 3 and the reflector 4. In this specification, the polygon mirror 2
The condenser optical element 3 and the reflecting mirror 4 are collectively referred to as a reflective illumination optical system.

On the mask 5, a pattern similar in shape to the pattern to be drawn on the wafer 7 held on the wafer stage 7s is formed. The pattern on the mask 5 is illuminated by a reflective illumination optical system, and is projected onto a wafer 7 through a projection optical system 6 including aspherical reflecting mirrors 6a, 6b, 6c, and 6d. Thus, the pattern formed on the mask 5 is projected onto the wafer 7.

Incidentally, the optical field of view of the projection optical system 6 is arc-shaped and is not wide enough to cover the entire device chip to be manufactured. The mask 5 and the wafer 7 are relatively moved (scanned) in synchronization with each other. By performing exposure, a pattern of the entire chip is formed on the wafer.

For this purpose, there are provided a mask stage controller 8 including a laser interferometer for controlling the amount of movement of the mask stage 5s and a wafer stage controller 9 for controlling the amount of movement of the wafer stage 7s. (Refer to the above-mentioned reference 1 for the exposure method involving this scan.)

The polygon mirror 2 is used to optically form a plurality of secondary light sources from the light from the light source 1.
Therefore, the polygonal reflecting mirror 2 has a plurality of minute element reflecting surfaces having the same contour of each reflecting surface, and there are a plurality of types of element reflecting surfaces, and the element reflecting surfaces are repeatedly arranged for each surface shape. ing. The outer shape of the element reflecting surface is similar to the optical field of view of the projection optical system. As a result, a number of point light source images I are formed at the position P2, which form the required illumination field by the condenser optical element 3. By using the above-described technique, the area to be illuminated on the mask can be uniformly illuminated without waste, the exposure time can be reduced, and a semiconductor exposure apparatus having high throughput can be realized.

By the way, when a single substrate is manufactured by cutting using a cutting machine equipped with a ball end mill, a shape as shown in FIG. 7 is obtained. In this manner, the unprocessed CR is formed at a portion where the element reflection surfaces 51 are adjacent to each other.
It was found that the light applied to this portion did not reflect to a predetermined position. When there is light that is not reflected at a predetermined position, the amount of light illuminated on the mask 5 decreases, and the exposure time on the wafer 7 increases. As a result, the exposure apparatus has a low throughput.

An embodiment of the present invention for solving such a problem will be described. (First Embodiment) An embodiment according to the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram illustrating a method for processing an optical element that is a polygon mirror 2 according to an embodiment of the present invention.

FIG. 8 is a view showing the concept of a processing method according to the present invention. The procedure of the manufacturing method according to the embodiment of the present invention will be described below with reference to FIGS. First,
A metal, glass or ceramic block is prepared (S001). When considered as an X-ray reflector,
Since the X-rays that have not been reflected completely become heat and heat the reflecting mirror itself, those having a relatively low coefficient of thermal expansion are preferable.
Materials that can be used as the block include silicon, ULE, super Invar, oxygen-free copper, Invar, aluminum, carbon steel, quartz glass, Starbucks, and Pyrex glass.

Next, the prepared block is processed into a cylinder having a predetermined radius of curvature R1 and length L1 as shown in FIG. 8A (S002). As shown in FIG. 8B, the block processed into a cylinder is cut into a semi-cylindrical member having a desired height H1 (S003). By joining through the side surfaces of the cut-out Kamaboko-shaped members as shown in FIG. 9, a high-precision polygon mirror as shown in FIG. 3 is completed (S004).

The above embodiment is limited to the case where the shape of the reflecting mirror is convex. However, when the shape of the reflecting mirror is concave, it is manufactured by the following method. First, a metal, glass or ceramic block is prepared. next,
The prepared block is processed into a cylinder having a desired radius of curvature R2 and length L2 as shown in FIG. As shown in FIG. 10B, the block processed into a cylinder has a desired width W.
Cut out into 2 in the shape of a kamaboko. The bottom surface of the cut-out suspected crab-shaped member is processed. By joining through the side surfaces of the quasi-cylindrical member, a high-precision polygon mirror as shown in FIG. 4 is completed. (Second Embodiment) Next, a second embodiment will be described. As shown in FIG. 11, a mold bit having a desired reflection surface shape is manufactured. The prepared aluminum alloy is shaved with a die. A multifaceted mirror is completed in one process.

However, in the above-described method, a large amount of processing removal is required to create a convex shape from a flat surface, and it takes a long time. Therefore, a tool having a plurality of same-shaped total cutting tools may be prepared. When the workpiece is a brittle material such as glass or ceramics, a tool provided with a plurality of mold wheels as shown in FIG. 12 may be used. In FIG. 12, the mold wheels can be broadly classified into a rough grinding section 500 composed of a plurality of grinding wheels and a fine grinding section 550 composed of a plurality of fine grinding wheels. The forming grindstone first processes the workpiece in the rough grinding section 500, moves to the arrow Y500, and then moves the fine grinding section 5
At 50, the workpiece is processed. The forming wheel rotates in the direction of arrow A500 about axis O500. The workpiece moves in the direction of arrow X500.

It is preferable that an aluminum thin film is formed to have a thickness of about 100 nm by vapor deposition in order to increase the reflectance of the surface thus processed. Further, magnesium fluoride was formed thereon by vapor deposition to a thickness of several tens nm from the viewpoint of preventing oxidation and maintaining the reflectance.
This makes it possible to efficiently reflect the light of the wavelength emitted from the F ₂ laser. Further, when light (electromagnetic waves) in the soft X-ray region is used, it is preferable to form a multilayer film of silicon and molybdenum (see the above-mentioned reference document 1).

[0029]

As described above, according to the processing method provided by the present invention, a reflector having a complicated shape composed of many reflecting surfaces can be manufactured with high precision and high processing efficiency. The reflecting mirror obtained by this manufacturing method is suitable for a lighting device for a semiconductor device manufacturing apparatus.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a processing procedure according to an embodiment of the present invention.

FIG. 2 is a schematic configuration diagram of an optical system of an exposure apparatus using a polygon mirror formed by a processing procedure according to the present invention.

FIG. 3 is a schematic diagram of a reflective convex cylindrical integrator.

FIG. 4 is a schematic view of a reflective concave cylindrical integrator.

FIG. 5 is a diagram showing the shape of a ball end mill and a curved surface that can be processed.

FIG. 6 is a cross-sectional view of a reflective convex cylindrical integrator formed by a conventional processing method.

FIG. 7 is a view showing a shape of a polygon mirror formed by a conventional processing method.

FIG. 8 is a view showing the concept of a processing method according to the present invention.

FIG. 9 is a view showing a cut-out cambular member.

FIG. 10 is a view showing the concept of a processing method according to the present invention.

FIG. 11 is a view showing a processing method according to the present invention.

FIG. 12 is a view showing a processing method according to the present invention.

[Explanation of symbols]

2 Polyhedral mirror 3 Condenser optical element 4 Reflector 5 Mask 6 Projection optical system Wafer 51 ..... Element reflection surface formed by conventional processing method

Claims (7)

[Claims] 1. A method for manufacturing a reflector, comprising forming a plurality of element reflecting surfaces having a part of a predetermined curved surface as a surface shape, wherein a step of processing an outer shape or an inner diameter to a predetermined radius of curvature; A method for manufacturing a reflecting mirror, comprising: a step of cutting a member processed into a radius into a predetermined size; and a step of arranging the member cut into the predetermined size at a predetermined position. 2. A method for manufacturing a reflector, comprising forming a plurality of element reflecting surfaces each having a part of a predetermined curved surface as a surface shape, wherein the predetermined curved surface is processed only by a cutting step or a grinding step. Manufacturing method of reflecting mirror. 3. A polygon mirror manufactured by the method for manufacturing a polygon mirror according to claim 1. 4. A reflection type illuminating device comprising the polygon mirror according to claim 3. 5. A light source, a mask stage for holding and moving a mask, an illuminating device for illuminating the mask with light from the light source, and a pattern on the mask illuminated by the illuminating device on a wafer. A projection optical device for projecting,
A semiconductor exposure apparatus having a wafer stage for holding and moving the wafer, wherein the illumination apparatus is the reflection-type illumination apparatus according to claim 4. 6. The semiconductor exposure apparatus according to claim 5, wherein the reflection type illumination device has a reflection surface of the polygonal reflection mirror having a shape similar to an optical field of view of the projection optical device. 7. The semiconductor exposure apparatus according to claim 5, wherein an optical field of view of said projection optical device is arc-shaped.