JP2000049082A - Charged particle beam projection aligner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a charged particle beam projection aligner by which foreign particles such as fine particles can hardly be adhered or deposited onto reticles, when they are used for projection exposure, transferred or stored. SOLUTION: An electron beam projection aligner provided with an electro- optical system with a horizontal optical axis having an illuminating electro- optical system 111 and projection electro-optical system 112 is placed in an evacuated case. A reticle is disposed in the aligner in such a way that its surface is vertical, since the optical axis of the electro-optical system is horizontal. Since the inner space of the evacuated case is close to vacuum state, fine particles produced in the case fall down vertically (in the A direction). Accordingly, the possibility of adhesion of fine particles to the surface of the reticle 101 can be reduced to an extremely low level.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charged particle beam projection exposure apparatus, and more particularly, to a charged particle beam projection exposure apparatus in which foreign matter such as dust is hardly adhered to a reticle used for projection exposure. Things.

[0002]

2. Description of the Related Art At present, in a light reduction projection exposure apparatus widely used as a method for fabricating a fine semiconductor circuit, a film called a pellicle transparent to light used for projection is arranged above and below a mask. This prevents contaminant particles from directly adhering to the mask. The image of the contaminating fine particles adhering to the pellicle is blurred without forming an image on the image forming surface (on the wafer), and thus does not affect the image formation of the mask pattern. As a result, the light reduction exposure apparatus prevents a decrease in yield due to contamination of fine particles on the mask, and a decrease in processing performance of the apparatus.

The minimum processing line width of a semiconductor circuit has been reduced year by year due to the high integration of semiconductors. However, in projection exposure using light (ultraviolet light), the minimum processing line width is restricted in principle by the diffraction limit. I have. Therefore, in order to perform finer processing, a method using X-rays or electron beams has been proposed. In electron beam projection exposure, which is one of them, a pattern formed on a thin film called a reticle is projected by an electron beam optical system. Since electrons can be narrowed down to an area smaller than light (ultraviolet light), fine processing that cannot be performed by light (ultraviolet light) is possible, and moreover, a wide area can be exposed at a time. Processing capacity is obtained.

[0004]

However, since electrons are largely absorbed by all substances and there is no transparent substance, the reticle used in this method cannot be protected from fine particles by a film like a pellicle. for that reason,
In a reticle used for electron beam projection exposure, it is indispensable to prevent deposition and adhesion of fine particles on the surface, or to detect and remove the attached fine particles.

[0005] The minimum particle diameter required to be removed by electron beam projection exposure is 0.1 µm or less. It is not technically easy to always detect the presence or absence of such fine particles, even during exposure, and to completely remove the fine particles if detected. In addition, it is difficult in a short time to completely detect the entire surface of a reticle having a diameter of 20 to 30 cm and on which a complicated and fine pattern is formed. Therefore, after completely cleaning the reticle just before being placed in the exposure apparatus,
It is desirable that fine particles do not adhere or accumulate on the reticle.
The same applies to the case where a charged particle beam other than the electron beam is used.

The present invention has been made in view of the above circumstances, and is a charged particle beam in which foreign matter such as fine particles hardly adheres or accumulates on a reticle when used for projection exposure, transport, or storage. It is an object to provide an exposure apparatus.

[0007]

According to a first aspect of the present invention, there is provided a charged particle beam projection exposure apparatus for projecting a pattern formed on a reticle onto an object surface by using a charged particle beam. The charged particle beam exposure apparatus according to claim 1, wherein the optical axis of the charged particle optical system for projecting light is substantially horizontal.

In this means, since the optical axis of the charged particle optical system for projecting the reticle image is substantially horizontal, the surface of the reticle is substantially vertical in use. Therefore, foreign matter such as fine particles adhere to the surface of the reticle.
The potential for deposition is greatly reduced.

[0009] A second means for solving the above-mentioned problems is as follows.
The first means, wherein the reticle used for exposure is stored and transported while keeping the reticle surface almost vertical (Claim 2).

In this means, the surface of the reticle is kept substantially vertical not only when it is used for exposure projection but also when it is stored and transported. So save,
During transportation, foreign matter such as fine particles adhere to the reticle surface.
The potential for deposition is greatly reduced.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows Embodiment 1 of the present invention.
It is a figure which shows the principal part of the example electron beam projection exposure apparatus. In FIG. 1, 101 and 102 are reticles, 111 is an illumination electron optical system, 112 is a projection electron optical system, 120 is a reticle stage, 130 is a reticle transport device, and 141 is a reticle loader.

In a container (not shown) evacuated to a vacuum,
Having an illumination electron optical system 111 and a projection electron optical system 112,
An electron beam projection exposure apparatus having an electron optical system having a horizontal optical axis is provided. The reticle 101 placed in this apparatus is placed so that the surface is vertical because the optical axis of the electron optical system is horizontal. Since the inside of the vacuum container is in a state close to a vacuum, the fine particles generated in the container fall vertically (direction A) in the container. Therefore, the possibility that the fine particles adhere to the surface of the reticle 10l can be extremely reduced.

Further, while the reticle is stored in the reticle loader 141, the reticle is taken out by the reticle transport device 130 and placed on the reticle stage 120.
The surface of the reticle is kept vertical, and the possibility that fine particles adhere to the surface of the reticle 101 during that time is also reduced. According to such an electron beam projection exposure apparatus, it is possible to suppress adhesion of fine particles and the like to the reticle without lowering the processing capability of the apparatus.

FIG. 2 is a diagram showing a main part of an electron beam projection exposure apparatus according to another embodiment of the present invention. In FIG. 2, 201 and 202 are reticles, 210 is an electron source, 2
11 is an illumination electron optical system, 212 is a projection electron optical system, 21
Reference numeral 3 denotes a wafer stage, 214 denotes a wafer, 220 denotes a reticle stage, 230 denotes a reticle transport device, 240 denotes a vacuum container, 241 denotes a reticle loader, 242 denotes a reticle cleaning device, and 243 denotes a reticle inspection device.

The inside of the vacuum vessel 240 is evacuated by an exhaust device (not shown) so that the pressure is 10 ^-4 Pa or less in order to prevent scattering of electrons. Vacuum container 24
An electron source 210, an illumination electron optical system 211, a reticle stage 220, a projection electron optical system 212, and a wafer stage 213 are arranged inside the reticle 201.
The upper pattern is projected and transferred onto the wafer 214 coated with the resist.

In this electron beam projection exposure apparatus, since the optical axis of the electron optical system is horizontal, the reticle 201 is arranged so that the surface thereof is in the vertical direction. In addition, the surface of reticle 201 is kept in the vertical direction during storage of reticle 201 in reticle loader 241 and during movement from reticle loader 241 to reticle stage 220.

The present electron beam projection exposure apparatus includes a reticle detecting device 242 for detecting fine particles attached to the reticle, and a reticle cleaning device 243 for removing and cleaning the fine particles when the fine particles are detected. The reticle used for a certain periodical exposure is transported to the reticle detection device 242, and when the reticle detection device 242 detects fine particles,
Cleaning is performed in the cleaning device 243. When the cleaning is completed, the reticle is conveyed to the reticle stage 220 again after confirming removal of the fine particles by the fine particle detector 242, and the exposure is restarted.

In the present electron beam projection exposure apparatus, the reticle is
Since the direction of the surface is always kept vertical, there is a very low possibility that the fine particles will adhere and accumulate as compared with the prior art in which the surface is horizontal. Therefore, the frequency of performing fine particle detection can be extremely reduced, and the time required for reticle replacement and the waiting time during cleaning are reduced, so that the processing capability of the apparatus can be kept high.

[0019]

As described above, in the present invention, the optical axis of the charged particle optical system for projecting a reticle image is made substantially horizontal, so that the surface of the reticle is substantially in use. It is kept vertical, which makes it difficult for fine particles to adhere to the reticle surface. As a result, an electron beam projection exposure apparatus having a high processing capability can be realized.

[0020]

[Brief description of the drawings]

FIG. 1 is a diagram showing a main part of an electron beam projection exposure apparatus which is an example of an embodiment of the present invention.

[0021]

FIG. 2 is a diagram showing a main part of an electron beam projection exposure apparatus as another example of the embodiment of the present invention.

[0022]

[Explanation of symbols]

 101, 102, 201, 202 reticle 111, 211 illumination electron optical system 112, 212 projection electron optical system 120, 130 reticle stage 130, 230 reticle transport device 141, 241 reticle loader 210 electron source 213 Wafer stage 214 ... Wafer 240 ... Vacuum container 243 ... Reticle inspection device A ... Falling direction of fine particles

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Claims (2)

[Claims] 1. A charged particle beam projection exposure apparatus for projecting a pattern formed on a reticle onto an object surface by a charged particle beam, wherein an optical axis of a charged particle optical system for projecting a reticle image is substantially horizontal. Characterized particle beam exposure equipment. 2. The charged particle beam projection exposure apparatus according to claim 1, wherein the reticle used for exposure is stored and transported while keeping the reticle surface almost vertical.