JP2961588B2 - Cooling device for reflecting mirror for synchrotron radiation - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reflection mirror for synchrotron radiation (hereinafter referred to as SOR light), and more particularly to a cooling device for a reflection mirror.

[0002]

2. Description of the Related Art SOR light is white light having a wide spectral range, and its brightness is extremely high. Normally, transmission of SOR light is performed in a vacuum to avoid scattering attenuation. Therefore, the reflection mirror used for deflecting SOR light is SOR light.
Despite receiving a large heat load due to light, it is used in a state where the surroundings are vacuum insulated, and its cooling is a major issue.

Conventionally, as shown in FIG.
The holder 52 holding the mirror 1 is brought into contact with the heat sink 53 to be cooled by heat conduction, or as shown in FIG. 6, the holder 52 holding the reflection mirror 51 is provided with a cooling water passage 54 to be water-cooled. The method of indirect cooling is common.

On the other hand, as shown in FIG. 7, a cooling water passage 54 is provided in the reflection mirror 51 held by a holder 52 to directly cool the water by water cooling.

[0005]

However, in the indirect cooling method shown in FIGS. 5 and 6, even if the average temperature of the entire mirror block including the reflecting mirror 51 and the holder 52 is lowered, the SOR light of the reflecting mirror 51 is reduced. In the vicinity of the outermost surface involved in the reflection of light, a heat load is applied, and the temperature difference from the other portions still remains, so that the problem of thermal deformation of the reflection surface cannot be solved.

Further, in the direct cooling method shown in FIG. 7, since it is necessary to provide a water path in the reflection mirror itself, it is necessary to secure rigidity by using a channel structure or the like in order not to impair the surface accuracy of the reflection mirror 51. Yes, the structure becomes complicated. Further, since the surface of the reflection mirror 51 cannot be completely and uniformly cooled, the shape of the cooling water channel appears on the mirror surface in a thermal and mechanical form, which causes a problem that the surface accuracy of the mirror is reduced.

The present invention eliminates the above-mentioned drawbacks of the conventional cooling device, and provides a cooling device for a synchrotron radiation reflecting mirror which can be cooled by a device having a simple structure while maintaining the surface accuracy of the reflecting mirror. The purpose is to do so.

[0008]

According to the present invention, there is provided a first radiation-transmissive partition for introducing synchrotron radiation,
A mirror box comprising an airtight container having a second radiant light transmissive partition arranged to derive the introduced synchrotron radiation, and the first radiant light transmissive disposed in the mirror box A reflecting mirror for reflecting and deflecting the synchrotron radiation introduced through the partition wall, and introducing helium gas into the mirror box from a helium gas introduction port provided in the mirror box; To the outside through a helium gas outlet provided in the mirror box, and the reflection mirror in the mirror box is
A cooling device for a synchrotron radiation light reflecting mirror, characterized in that a liquid-cooled cooling plate is arranged opposite to the mirror.

[0009]

Further, the reflection mirror may be held by a holder, and the holder may be provided with a cooling unit.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram showing a configuration of an SOR light deflection system such as an exposure apparatus used for manufacturing a semiconductor integrated circuit to which the present invention is applied. The SOR light 13 is extracted from the electron storage ring 11 to the first beam duct 12 in a vacuum state, and introduced into the mirror box 14 through the first SOR light transmitting partition 15. The first beam duct 12
An acoustic delay line for delaying shock wave propagation is provided by disposing a plurality of annular disks at intervals in the interior. The mirror box 14 is an airtight container, in which the first SOR light-transmitting partition wall 1 is provided.
A reflection mirror 16 for reflecting and deflecting the SOR light 13 introduced through the lens 5 is held by a holder 17 so as to be deflectably driven by a drive mechanism (not shown). The SOR light reflected and deflected by the reflection mirror 16 is evacuated through a second SOR light transmitting partition 18 disposed at a position facing the first SOR light transmitting partition 15 in the mirror box 14. It is led out to the second beam duct 19 and is taken out from the SOR light taking-out window 20 at the end of the second beam duct 19.

In the mirror box 14, a cooling plate 21 is fixedly disposed by a support 22 so as to face the reflection mirror 16. Then, helium (He) gas is introduced into the mirror box 14 from a helium gas inlet 23 provided near the first SOR light transmitting partition 15 of the mirror box 14, and the introduced helium gas is supplied to the mirror box 14. The gas is exhausted from a helium gas outlet 24 provided in the vicinity of the second SOR light transmitting partition 18.

The helium gas is supplied to the first and second SOs.
Mirror box 1 divided by R light transmitting partitions 15 and 18
4 that is filled so as to maintain a high-purity helium atmosphere at a predetermined pressure and uses a helium gas as a circulating cooling medium to directly and uniformly cool the surface of the reflecting mirror 16 by heat transfer with the inner wall of the mirror box 14 or the cooling plate 21. It is.

The inside of the first beam duct 12 on the side of the SOR ring 11 of the first SOR light-transmitting partition wall 15 needs to be maintained at an ultra-high vacuum. Therefore, the first SOR light-transmitting partition wall 15 is made of a thin film of, for example, beryllium (Be) or polyimide, which has a good vacuum sealing property and a high SOR light transmittance. As another method, the first SOR light-transmitting partition wall 15 may be used as a slit, and the upstream and downstream may be differentially evacuated to maintain an ultra-high vacuum upstream. Further, a high-speed shut-off valve is provided upstream of the first SOR light-transmitting partition 15 in order to prevent the SOR ring 11 as a light source from being broken in a vacuum due to breakage of the first SOR light-transmitting partition 15. The reliability is ensured by installing the acoustic delay line and the like described above.

The inside of the second beam duct 19 is a portion for extracting SOR light, and is not necessarily required to be in an ultra-high vacuum. Rather, it is desirable to use a He atmosphere due to thermal problems of the SOR light extraction window 20 and the like. There is. Therefore, the second
The SOR light-transmitting partition wall 18 can be provided as needed by selecting the atmosphere in the second beam duct 19.

FIG. 2 is an enlarged side sectional view showing the mirror box 14 of FIG. 1, and the same components as those of FIG. 1 are denoted by the same reference numerals. A coolant passage is provided in the cooling plate 21 facing the reflection mirror 16, and cooling water or cooling liquid nitrogen is supplied from a supply port 25 to the coolant passage via a coolant passage provided in the support 22. And support 2
The cooling plate 21 is discharged from a discharge port 26 through a refrigerant passage provided in the cooling plate 21. The holder 17 holds the reflection mirror 16 and has a function of deflecting and driving the incident SOR light.

The reflection mirror 1 is formed by circulation and exhaust of He gas.
The inside of the mirror box 14 in which 6 is installed is maintained in a high-purity He atmosphere of several Torr to 1 atmosphere. As shown in FIG. 4, He has a higher thermal conductivity than other gases (nitrogen
(6 times as much as oxygen and 3 times as much as neon) In addition, since the X-ray transmittance is high (99% at 1 m at 20 Torr), the SOR
A good heat transfer path is secured with the surroundings (mirror box 14, cooling plate 21, etc.) with little scattering attenuation of light.

FIG. 3 shows another embodiment of the present invention.
FIG. 2 is an enlarged side sectional view showing a mirror box 14 of FIG. 1. In this embodiment, the He gas pressure in the mirror box 14 is set to 1
Mirror box 14 through He gas by increasing the pressure to about atmospheric pressure
By improving the efficiency of heat transfer with the inner wall and absorption of heat by the exhausted He gas, the cooling plate 21 shown in FIG. 2 can be omitted.

As schematically shown in FIG. 4, a passage for He gas is provided in the cooling plate as shown in FIG. 2, and He gas is blown onto the reflecting mirror 16 from the surface facing the reflecting mirror 16. Alternatively, the cooling effect may be increased.

[0020]

According to the apparatus of the present invention described above, the entire reflecting mirror is in the He atmosphere and is uniformly cooled. In particular, since the surface of the reflecting mirror which receives a heat load related to the reflection of the SOR light is directly cooled to the He gas as the refrigerant, the cooling effect is large, and the thermal deformation near the surface is reduced.

Further, by maintaining the surroundings of the reflecting mirror in an atmosphere of He gas flow, a heat transfer path is generated between the reflecting mirror and the surroundings (cooling plate, mirror box), and the reflecting mirror can be cooled uniformly and with a large capacity. And

Further, by providing a highly pure He atmosphere around the reflection mirror, heat transfer can be performed in a state where scattering attenuation of SOR light is small.

In addition, apart from the problem of heat, the reflecting mirror is set to H
By placing the mirror in the e atmosphere, the mirror surface can be kept clean. That is, the probability that molecules (mainly carbohydrates) contaminating the reflecting mirror due to the presence of He molecules near the mirror surface will collide with and adhere to the mirror surface will be significantly reduced.

Further, in order to make the mirror surface and the driving device directly and large-capacity cooling possible with the increase in the brightness of the irradiated SOR light or the output of the reflecting mirror driving device, This is an effective means that can guarantee surface accuracy and reflection efficiency.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a configuration of an SOR light deflection system to which the present invention is applied.

FIG. 2 is a side sectional view showing a mirror box 14 of FIG. 1 in an enlarged manner.

FIG. 3 is an enlarged side sectional view showing a mirror box according to another embodiment of the present invention.

FIG. 4 is a graph showing the relationship between He gas pressure, heat transfer coefficient, and X-ray transmittance for explaining the operation of the present invention.

FIG. 5 is a view showing a conventional method for cooling an SOR light reflecting mirror.

FIG. 6 is a view showing another cooling method of the conventional SOR light reflecting mirror.

FIG. 7 is a view showing still another cooling method for a conventional SOR light reflecting mirror.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 SOR ring 12 1st beam duct 13 SOR light 14 Mirror box 15 1st SOR light transmissive partition wall 16 Reflection mirror 17 Holder 18 2nd SOR light transmissive partition wall 19 2nd beam duct 20 SOR light extraction window 21 Cooling plate 23 Helium gas inlet 24 Helium gas outlet

Claims (2)

(57) [Claims] A hermetic seal having a first radiating light transmitting partition for introducing synchrotron radiation and a second radiating light transmitting partition arranged to guide the introduced synchrotron radiation. A mirror box comprising a container; and a reflecting mirror disposed in the mirror box for reflecting and deflecting the synchrotron radiation light introduced through the first radiation-transmitting partition, and provided in the mirror box. and the helium gas helium gas from the inlet is introduced into the mirror box, and the introduced helium gas to derive the outside from the helium gas discharge port provided in the mirror box, before
The liquid-cooled cooling plate faces the reflection mirror in the mirror box.
A cooling device for a reflecting mirror for synchrotron radiation, wherein the cooling device is arranged . 2. The cooling device according to claim 1, wherein
The reflecting mirror is held by a holder, and a cooling unit is installed in the holder.
A cooling device for a reflecting mirror for synchrotron radiation, characterized in that it is radiated.