JPS6372117A - X-ray exposure device - Google Patents

Abstract

PURPOSE:To allow an exposure chamber to have an atmospheric pressure without destroying the vacuum of an X-ray source by composing a mechanism so that it may apply X-rays nearly uniformly to a part of a wafer to be irradiated with the X-ray with the movement of an X-ray transmission aperture or with X-ray scanning interlinked with the movement of the X-ray transmission aperture. CONSTITUTION:A beryllium aperture 9 has a structure where a flat opening 10 is covered by a beryllium film 11 of about 20mum thickness and a beam 6 is introduced into an atmospheric exposure part having a mask 7 and a wafer 8, thereby keeping a vacuum inside a vacuum container 3. Once the beryllium aperture 9 is moved with the movement interlinked with oscillation scanning of the beam 6, the whole pattern region of the mask 7 can be irradiated with the beam so as to expose the wafer 8. Even the beryllium thin film may withstand a differential pressure developed between a vacuum state and an atmospheric pressure by making each opening 10 of the beryllium aperture 9 smaller. As a result, even though an exposure chamber is at the atmospheric pressure, a high X-ray exposure intensity of illumination can be obtained and a highly practical X-ray exposure device can be formed.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an X-ray exposure apparatus for transferring patterns of semiconductor integrated circuits, and is particularly suitable for X-ray exposure when synchrotron radiation is used as an X-ray source. 0 Related to Equipment [Prior Art] One of the manufacturing processes for semiconductor integrated circuits is a so-called lithography process in which a circuit pattern is formed on a wafer. To form a pattern, an X-ray exposure method with a shorter wavelength is used. The exposure principle is extremely simple, in which the mask and wafer are placed close to each other and X-rays are irradiated from above the mask, but in order to obtain high throughput, a powerful X-ray source is required. Therefore, an X-ray exposure apparatus using synchrotron radiation as a light source has been devised. (
(For example, see Japanese Patent Application Laid-open No. 59-69927.) [Problems to be solved by the invention] The ring that generates synchtron radiation must be operated in an ultra-high vacuum, but on the other hand, the mask requires temperature stabilization. Therefore, it is desirable that it be in gas. Therefore, conventionally, the ring part and the exposure part where the mask and wafer are placed are connected to the IJ.
The exposure chamber is vacuum-separated with an IJ film, and there are several tens of tons of space inside the exposure chamber.
He gas of rr was flowing. Beam IJ Ijium is a material that easily transmits X-rays, but it is
In order to transmit a wavelength of about 20λ, the film thickness needs to be about 20 μm or less. On the other hand, the size of the opening of the beryllium window in the conventional device is usually 507 to 7
It is approximately 0φ, and this is determined from the exposure area required for exposing the circuit pattern. With a film thickness of 20 μm for the area of this opening, it would be impossible to withstand atmospheric pressure, and conventionally it was unavoidable to use a pressure difference of several Torr.

As mentioned above, in the past, it was not possible to maintain the exposure chamber at atmospheric pressure due to the limitations of the wafer window. When considering handling issues, it is essential to maintain the exposure chamber at atmospheric pressure.

The present invention has been made to solve the above-mentioned problems, and provides a technique that can bring the exposure chamber to atmospheric pressure without impairing the degree of vacuum of the X-ray source.

[Means for solving problems]

The above-mentioned object of the present invention is to provide an X-ray exposure system having an X-ray source, an exposure section having an X-pure mask and a wafer, and an X-ray transmission window that vacuum-blocks the X-ray source and the exposure section and transmits the X-rays. In the apparatus, the X-ray transmitting window has an X-ray transmitting portion having an area smaller than a portion where the X-pure mask and the wafer are irradiated with X-rays;
This is achieved by configuring the XIfM irradiation area of the wafer to be approximately uniformly irradiated with X-rays by moving the X-ray transmission window or by scanning the X-rays and moving the X-ray transmission window.

According to a preferred embodiment of the present invention, the X-ray transparent window has an X-green transparent portion made of beryllium that matches the shape of the X-ray beam, and the X-ray transparent window is moved in conjunction with the scanning of the X-ray beam. [Function] According to the above structure, the area of the X-ray transmitting part can withstand the pressure difference between the atmospheric pressure and the atmospheric pressure without affecting the exposure of X-rays to the Xi mask and wafer. It can be made as small as
The exposure area can be brought to atmospheric pressure without impairing the degree of vacuum of the X and B sources.

〔Example〕

Hereinafter, the present invention will be explained in detail using examples.

FIG. 1 shows an embodiment of the present invention. The X-rays emitted from the ring section become a flat, band-shaped beam 2 that travels inside the vacuum container 3 and enters a reflecting mirror 4. The reflecting mirror 4 rotates and vibrates around a rotation axis 5 perpendicular to the plane of the drawing, and vibrates and scans the reflected beam 6 over the mask 7 and wafer 8. Be IJ IJ
As shown in FIG. 2, the wafer window 9 has a structure in which a flat opening 10 is covered with a 71J wafer film 11 having a thickness of approximately 20 μm, and the beam 6 is directed through the mask 7 and the wafer while maintaining the vacuum of the vacuum chamber 3. 8 is placed in the atmospheric pressure exposure section. The shape of the flat aperture 10 is made to match the axial cross-sectional shape of the synchrotron beam 6. The above IJ ll
The material of the ram 9 itself may be a sufficiently thick aluminum plate, or any material that can block X-rays may be used.

By moving the beam window 9 in conjunction with the vibration scanning of the beam 6, the entire pattern area of the mask 7 can be irradiated and the wafer 8 can be exposed. The vertical movement of the window 9 may be linked with the rotation of the reflecting mirror 4, and may be linked using electrical signals in addition to mechanical linkage. In order to move the bellows window 9 up and down while maintaining a vacuum, the bellows 12 is connected between the bellows window 9 and the vacuum vessel 3.

With the above configuration, it is possible to obtain a wide exposure area while using a window with a small opening, and as a result, it is possible to withstand a large differential pressure even though the window has a thin film thickness. To give a specific example, the slit width of the opening 10 is 0.7
If the thickness of the beryllium film is 5 mm and the thickness of the beryllium film is 20 m, it can withstand a pressure difference of 1 atm. The transmittance of X-rays for a film thickness of 20 μm varies depending on the wavelength, but in the case of 12 wavelengths, the transmittance is about 15%.

An invention that can improve the transmittance of X-rays by further reducing the thickness of the film will be described below.

As shown in FIG. 3, the slit-shaped opening of the beryllium window is not made into one opening, but a large number of smaller slanted slits 12 are arranged regularly, and the whole is formed to look like one flat window. By scanning the mask 7 and wafer 8 in the direction of the arrow 13 while applying the X-ray beam from behind the small slit group, the wafer 8 can be exposed in the same way as when scanning with a single slit. can.

By reducing the area of one opening as described above, strength can be maintained even if the thickness of the beryllium film is reduced, and X-ray transmittance can be improved. For example, if the width d of the small slit 12 is tooam, the thickness of the base film to withstand 1 atm is only 2
~3 μm is sufficient.

The transmittance of the aluminum film at this thickness for 12 wavelengths is 80% or more, and an exposure optical system with extremely low loss can be realized.

The shape, arrangement pitch, etc. of the small slits 12 are determined depending on the allowable amount of unevenness in the cumulative exposure amount applied to the wafer. When the scanning speed of the window is constant, the planar shape of the small slits 12 may be determined so that the sum of the lengths of the small slits 12 in the scanning direction 13 is equal. For example, it can be easily realized even if it is a summer style.

Still another embodiment of the present invention will be described with reference to FIG. As shown in the half cross-section of FIG.
It has a structure in which an IJ film 11 is pasted, and this opening 10 allows X-rays to pass therethrough, while at the same time having the function of completely blocking the vacuum.

The window 9 and the vacuum container 3 are connected by a bellows 12. If exposure is performed by scanning the X-ray beam 6 with the window 9 fixed, the shadow of the light-shielding portion of the window 9 will be transferred onto the wafer 8, but in the present invention, the window 9 is vibrated at high speed,
The shadow of the light shielding part of the window 9 is evenly dispersed. As a result, the pattern of the mask 7 is transferred onto the wafer 8 without uneven illumination.

By making each opening 10 of the beryllium window 9 small as described above, even a thin beryllium film can withstand the pressure difference from atmospheric pressure. For example, if the opening is a circle with a diameter of 100 μm, the thickness of the beryllium film is 2 to
A thickness of 3 μm is sufficient for strength. With this film thickness, more than 80% of X-rays with wavelengths of 10 to 12 people are transmitted. As a result, high X-ray exposure illuminance can be obtained while keeping the exposure chamber at atmospheric pressure, making it possible to realize an extremely practical X-ray exposure apparatus.

The shape and arrangement pitch of the small openings 10 must be determined in consideration of the vibration form of the window 9 as a whole. In other words, the cumulative amount of transmitted X-rays should be uniform at all locations, but the vibration amplitude may be sufficiently large relative to the array pitch.
For example, if there are about 10 pitches, there will be almost no unevenness in illuminance. The form of vibration needs to move vertically and horizontally.
For example, rotational vibration may be made in a circular manner. Alternatively, random vibration may be used.

There are various methods of manufacturing the window 9.

A sufficiently thick aluminum plate may be etched only at the opening so that a slight thickness remains, or it may be penetrated and the aluminum thin film bonded thereto.

In the latter case, if the thin film is placed on the atmospheric pressure side, the tensile strength of the bonded portion is hardly required.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to expose the mask and wafer in the atmosphere, and the X-ray transmitting part can be made smaller, so the members of the X-ray transmitting part can be made thinner. Therefore, high X-ray transmittance can be obtained.

As a result, high throughput can be obtained, mask temperature can be easily controlled, and wafers can be vacuum chucked. Since wafers can only be exchanged in the atmosphere, the system has many advantages, such as simplifying the equipment configuration.

[Brief explanation of the drawing]

FIG. 1 is a side view of an X-ray exposure apparatus showing the principle of the present invention, FIG. 2 is a front view and side view of a beam window showing an embodiment of the invention, and FIG. FIG. 4 is a front view of a beryllium window in which a large number of small slits are arranged, showing an embodiment of the present invention, and FIG. 4 is a perspective view of a beryllium window showing still another embodiment of the present invention. l... Synchrotron ring, 2... X-ray beam 4... Reflector, 7... Mask, 8... Wafer, 9
... Beryllium window, 12... Bellows, 11...
Beryllium film. ),

Claims (1)

[Claims] 1. An X-ray device having an X-ray source, an exposure section having an X-ray mask and a wafer, and an X-ray transmission window that vacuum-blocks the X-ray source and the exposure section and transmits the X-rays. In the radiation exposure apparatus, the X-ray transmission window has an X-ray transmission part with an area smaller than the area where the X-ray mask and the wafer are irradiated with X-rays, and the movement of the X-ray transmission window or the scanning of X-rays and the Due to the movement of the line-transmitting window, the X of the wafer
An X-ray exposure apparatus characterized in that the X-ray exposure apparatus is configured to irradiate X-rays substantially uniformly onto a portion to be irradiated with X-rays. 2. In the thing described in claim 1, the above-mentioned X
The radiation-transmitting window has an X-ray transmission part that matches the shape of the X-ray beam,
An X-ray exposure apparatus characterized in that an X-ray transmission window is configured to move in conjunction with scanning of an X-ray beam. 3. In the thing described in claim 2, the above-mentioned X
An X-ray exposure apparatus characterized in that the X-ray transmitting section of the X-ray transmitting window is composed of a plurality of X-ray transmitting openings arranged obliquely with respect to the moving direction of the X-ray transmitting window. 4. In the thing described in claim 1, the above-mentioned X
An X-ray exposure apparatus, characterized in that the radiation transmission window has a plurality of X-ray transmission openings, and the X-ray transmission window is configured to vibrate in a plane perpendicular to the direction in which X-rays travel.