JP2004039851A - Mirror cooling device and aligner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that there is possibility of affecting an influence of an application of a force to an optical element due to a contact of a cooling device with the element for causing a mirror to be deformed or transmitting a vibration of the device to the mirror to an exposure performance, though a method for cooling the element by bringing the device into contact with the element is considered. <P>SOLUTION: A mirror cooling device includes an electronic cooling element for cooling the mirror, a spring-like member disposed between the mirror and the cooling element, a heat transfer element for transferring a heat discharged from the cooling element, and a cooling mechanism for cooling the heat transfer element. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an apparatus for cooling a mirror used in a vacuum and an exposure apparatus to which such an apparatus is applied. In particular, the present invention relates to an apparatus and method for cooling a mirror and suppressing thermal deformation in a precision optical apparatus such as an EUV (extreme ultraviolet light) exposure apparatus. The mirror in the present invention is a concept including a reflection mask.
[0002]
[Prior art]
The prior art will be described using an EUV light (extreme ultraviolet light) exposure apparatus as an example.
FIG. 8 is a diagram showing a schematic configuration example of an EUV exposure apparatus.
[0003]
The exposure apparatus shown in FIG. 8 includes an EUV source 101, an illumination optical system 103 for irradiating a reflective mask 102 with EUV light (wavelength 13.4 nm) 100 emitted from the EUV source 101, and a circuit pattern on the reflective mask 102. And an EUV projection optical system 105 for projecting the light onto a wafer 104, a mask stage 106 and a wafer stage 107.
[0004]
In this exposure apparatus, EUV light 100 emitted from an EUV source 101 is applied to a reflective mask 102 via an illumination optical system 103. The EUV light 100 reflected by the reflective mask 102 enters the projection optical system 105. The EUV light 100 that has passed through the projection optical system 105 reaches the wafer 104, and the pattern on the reflective mask 102 is reduced and transferred onto the wafer 104.
[0005]
The projection optical system 105 is composed of, for example, six multilayer film reflecting mirrors (not shown), and the reduction magnification is, for example, １ ／. The projection optical system 105 has a ring-shaped exposure field of view having a width of 2 mm and a length of 30 mm on the wafer 104. Each reflecting mirror has an aspherical reflecting surface, and a Mo / Si multilayer film for improving the reflectivity of EUV light is formed on the surface thereof. During exposure, the reflective mask 102 and the wafer 104 are scanned on stages 106 and 107, respectively. The scanning speed of the wafer 104 is synchronized so as to always be 1/4 of the scanning speed of the reflective mask 102. As a result, it is possible to transfer a pattern that spreads over an area larger than the field of view of the optical system.
[0006]
Next, the mechanical structure of the optical system barrel will be described in more detail with reference to FIG.
FIG. 9 is a configuration diagram illustrating an example of an optical system barrel of the EUV light exposure apparatus.
[0007]
FIG. 9 shows an optical system barrel 110 that holds two reflecting mirrors (optical elements) 111 and 112. The lens barrel 110 has a lens barrel body 110a and a flange 110b. The lens barrel 110 is made of Invar, and is unlikely to undergo thermal denaturation.
[0008]
The reflecting mirror 111 is held by a holding mechanism 116 via a position adjusting mechanism (such as a piezo motor) 115 on the flange 110 b of the lens barrel 110. The position adjusting mechanism 115 is a mechanism for adjusting the position of the reflecting mirror during or after assembly. On the other hand, the reflecting mirror 112 is held by the holding mechanism 117 below the flange 110 b of the lens barrel 110. Holes 111a and 112a are formed in the two reflecting mirrors 111 and 112, respectively. Light 100 emitted from a light source or a mask (not shown) at the top of the figure passes through a hole 111 a of the upper reflecting mirror 111 and reaches the upper surface of the lower reflecting mirror 112. Go to the bottom. The light 100 is further reflected by the lower surface of the reflecting mirror 111 and travels downward, and reaches a mask or a wafer (not shown) through the hole 112a of the reflecting mirror 112.
[0009]
In the EUV optical system, the Mo / Si multilayer film is formed on the surface of the reflecting mirror (optical element) as described above. The numerical aperture of the EUV projection optical system is, for example, 0.2 to 0.3, and the wavefront aberration is required to be 1 nm RMS or less. In order to realize such a small wavefront aberration, it is necessary to use an aspherical mirror having a highly accurate shape as a reflecting mirror and to assemble and adjust the mirror with high accuracy.
[0010]
[Problems to be solved by the invention]
The aforementioned reflector is heated by absorbing a part of the incident EUV light. Here, when the optical system barrel as shown in FIG. 9 is used in a vacuum atmosphere, the heat radiation of the heated reflector is poor, so that the reflector may be thermally deformed. Therefore, a method of cooling by bringing the cooling device into contact with the optical element can be considered. However, a force is applied to the optical element by the contact, and the mirror is deformed, and the vibration of the cooling device is transmitted to the mirror, thereby affecting the exposure performance. there is a possibility.
[0011]
The present invention has been made in view of such a problem, and an object of the present invention is to provide a mirror cooling device or the like that can cool a mirror while suppressing deformation and position change of the mirror.
[0012]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, a mirror cooling device according to the present invention includes an electronic cooling element for cooling a mirror, a spring-like member disposed between the mirror and the electronic cooling element, and a device that is discharged from the electronic cooling element. It is characterized by having a heat transfer element for transmitting heat and a cooling mechanism for cooling the heat transfer element.
[0013]
When the thermoelectric cooler and the mirror are in direct contact, the mirror shape may change.For example, such a mirror that requires high shape accuracy as used in an extreme ultraviolet light exposure apparatus is used. Deformation can be unacceptable. On the other hand, here, since the electronic cooling element (Peltier element) and the mirror are connected by a spring-like member, the deformation of the mirror can be reduced. It is also possible to suppress the transmission of the vibration of the cooling device to the mirror.
[0014]
Here, the spring-like member is a member having relatively low rigidity such as a leaf spring or a spring. Since the spring-like member needs to propagate heat from the mirror, it is preferable to form the spring-like member from a material having a high thermal conductivity because the cooling efficiency is improved. Further, it is preferable that the material is made of a material having a small amount of outgas in a vacuum, or that a treatment that hardly generates outgas is performed. Further, it is preferable that the coefficient of thermal expansion is low so as not to deform the mirror.
[0015]
The cooling device for a mirror used in a vacuum according to the present invention, further comprising: an electronic cooling element disposed apart from the mirror; a heat transfer element for transmitting heat discharged from the electronic cooling element; And a cooling mechanism for cooling the element.
[0016]
Since there is a distance between the electronic cooling element (Peltier element) and the mirror, the electronic cooling element does not contact the mirror and is deformed. Further, it is possible to prevent the vibration of the cooling device from being transmitted to the mirror. In this configuration, the mirror can be cooled by the radiation effect. The electronic cooling element can be placed on any of the front, back, and side surfaces of the mirror. It is arranged in a certain non-effective area (peripheral part). Note that the gap between the mirror and the electronic cooling element is preferably about 0.1 mm to 3 mm from the viewpoint of assembly of the apparatus and cooling efficiency.
[0017]
Further, it is preferable to further provide a gas supply mechanism for supplying gas between the electronic cooling element and the mirror, and a gas exhaust mechanism for exhausting the supplied gas.
By flowing gas between the electronic cooling element and the mirror, heat moves from the mirror to the electronic cooling element via the gas, so that the heat of the mirror can be more efficiently transmitted to the electronic cooling element. As the gas, for example, helium or the like can be used. Further, since the supply and discharge of the gas can be performed simultaneously, it is possible to suppress the degree of vacuum in the vacuum chamber from being reduced. Since it is preferable that gas does not leak into the vacuum chamber as much as possible, a guard ring or wall should be provided so that the space created by the mirror and the electronic cooling element is a closed space so that gas does not leak. Is preferred.
[0018]
Further, a plurality of electronic cooling elements may be provided, and a control device for independently controlling each of the plurality of electronic cooling elements may be further arranged.
The mirror absorbs a part of the energy of light incident on the mirror and generates heat. Light incident on the mirror often enters a part of the mirror, and the intensity distribution is often non-uniform. Therefore, the energy absorbed by the mirror becomes spatially non-uniform, and the heat (temperature) distribution of the mirror tends to be non-uniform. When the heat distribution of the mirror becomes non-uniform, a part of the mirror may be deformed so as to expand and bend, and this deformation affects the wavefront aberration. However, by independently controlling the plurality of electronic cooling elements, it is possible to cool a desired position of the mirror independently, so that the temperature distribution of the mirror can be a desired distribution. Therefore, it is possible to make the temperature (heat) distribution of the non-uniform mirror uniform. Note that the temperature distribution of the mirror that changes due to the incidence of light or the like may be obtained in advance by an experiment or the like, or may be measured by disposing a temperature sensor. Each of the electronic cooling elements is controlled based on the temperature information of the mirror thus obtained.
[0019]
Further, a groove may be provided in the mirror, and the mirror may be cooled from the bottom of the groove.
By doing so, the distance between the position on the mirror surface where the light is irradiated and the electronic cooling element can be shortened, so that the mirror can be cooled more efficiently. In many cases, the mirror is generally made of a material having low thermal conductivity such as glass. Also, in order to increase the shape accuracy, it is necessary to increase the rigidity, and therefore, it is necessary to increase the thickness of the mirror. Therefore, in order to cool the mirror more efficiently, it is preferable that the thickness of the mirror is small, but it is not preferable to simply reduce the thickness of the mirror because the rigidity of the mirror is low. On the other hand, when the groove is provided, the rigidity does not need to be excessively reduced, so that the mirror can be efficiently cooled while keeping the rigidity of the mirror high. It is preferable to determine the shape of the groove so as to increase the rigidity of the mirror. For example, it is preferable to form a polygonal groove or adopt a honeycomb structure.
[0020]
The groove can be formed on the front surface, the back surface, and the side surface of the mirror. When the groove is formed on the front surface, the groove is arranged so as not to disturb a light beam incident on and reflected from the mirror.
Preferably, the heat transfer element is a heat pipe.
[0021]
The use of a heat pipe is superior in heat transfer capability as compared with simple heat conduction of a metal, and does not cause vibration or deformation due to the flow of the refrigerant as compared with a cold water pipe through which a refrigerant such as pure water flows. When the metal part constituting the heat pipe is made of a low thermal expansion metal such as Super Invar, the heat deformation of the heat pipe itself can be reduced. When the heat pipe is deformed, there is a possibility that the position and the shape of the member connected to the heat pipe are changed. For example, even if the mirror and the electronic cooling element are connected by a spring-like member, if the position of the electronic cooling element changes, the position change that could not be completely absorbed by the spring-like member may deform the mirror, so the heat as much as possible The thermal deformation of the pipe is preferably small.
[0022]
Further, it is preferable that the heat transfer element and the holding member that holds the mirror are connected via a spring-like member.
When the heat transfer element is held by a holding member (cell) that supports the mirror, it is preferable to interpose a spring-like member between the heat transfer element and the holding member. When fixing the heat transfer element to the holding member, a force is applied to the holding member without the intervention of a spring, and the holding member is deformed. Deformation of the holding member is not preferable because it adversely affects the shape of the mirror. The deformation of the holding member can be suppressed by interposing the spring-like member.
[0023]
Note that the spring-like member used here does not need to conduct heat, and thus does not need to have high heat conductivity, and preferably has low heat conductivity.
Further, it is preferable to insert a heat insulating member having a lower thermal conductivity than the spring-like member between the spring-like member and the holding member.
[0024]
When the heat of the heat transfer element is transmitted to the holding member, the holding member may be thermally deformed, which may adversely affect the deformation of the mirror. In order to avoid such a phenomenon, it is preferable to insert a heat insulating material between the heat transfer element and the holding member.
[0025]
It is preferable that the heat transfer element and the cooling mechanism are joined via a spring-like member. In this way, even if a cooling mechanism having a certain degree of vibration or being deformed is used, it is possible to reduce the influence on the heat transfer element and the components connected thereto.
[0026]
Further, an apparatus of the present invention for solving the above problem has an optical system including a plurality of mirrors, and in an exposure apparatus in which the optical system is arranged in a vacuum chamber, at least one of the plurality of mirrors is cooled. Cooling element, a first heat transfer element for transmitting heat exhausted from the cooling element, a second heat transfer element disposed through a wall of the vacuum chamber, a first heat transfer element, and a second heat transfer element. And a cooling mechanism that cools the second heat transfer element.
[0027]
When the heat transfer element connected to the cooling element is directly penetrated through the wall of the vacuum chamber and guided to the outside of the chamber, a force is applied to the heat transfer element, and the resulting deformation may cause the deformation of the mirror. . On the other hand, since the two heat transfer elements are used to connect the heat transfer elements with a spring-shaped member, even if a force is applied to the heat transfer element disposed through the chamber during assembly or the like, the first heat transfer element is connected. It is possible to suppress the transmission of the force to one heat transfer element.
[0028]
Preferably, an elastic member is arranged between the second heat transfer element and the chamber wall.
With this configuration, even if the chamber is deformed during evacuation, it is possible to suppress the application of force to the second heat transfer element. Bellows or the like can be used as the elastic member.
[0029]
Further, it is preferable to dispose a heat insulating member between the second heat transfer element and the chamber wall.
When heat on the surface of the chamber partition wall is transmitted to the heat transfer element, it becomes difficult to use the heat transfer element as designed. On the other hand, when the heat insulating member is disposed, the heat of the chamber wall is less likely to be transmitted to the second heat transfer element. Therefore, the second heat transfer element can be used as designed, and the second heat transfer element can be used. The cooling of the heat transfer element can be controlled as designed.
[0030]
According to another aspect of the present invention, there is provided an exposure apparatus having an optical system including a plurality of mirrors, wherein the optical system is disposed in a vacuum chamber. , A first heat transfer element for transmitting heat discharged from the cooler, a second heat transfer element disposed in the vacuum chamber, and a third heat transfer element disposed outside the chamber. A heat transfer element, a first spring-like member connecting the first heat transfer element and the second heat transfer element, and a second spring connecting the second heat transfer element and the third heat transfer element. And two spring-shaped members.
[0031]
Further, it is preferable that the second spring-like member is composed of two spring-like members, and the two spring-like members are connected via a vacuum chamber.
With this configuration, since the second heat transfer element and the third heat transfer element are connected to the chamber wall via the spring-like member, it is possible to suppress the deformation and vibration of the chamber from being transmitted to the heat transfer element. As a result, it is possible to prevent the mirror from being deformed.
[0032]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, description will be made with reference to the drawings.
First, an outline of the EUV light reduction projection exposure technique will be described with reference to FIG.
[0033]
FIG. 7 is a diagram showing an example of the overall configuration of an EUV light exposure apparatus.
The EUV light exposure apparatus in FIG. 7 is a projection exposure apparatus that performs an exposure operation by a step-and-scan method using extreme ultraviolet light (EUV) as illumination light for exposure.
[0034]
As shown in FIG. 7, a laser light source 203 is arranged at the most upstream part of the exposure apparatus 201. The laser light source 203 has a function of emitting laser light having a wavelength in the range from infrared to visible. For example, a YAG laser or an excimer laser excited by a semiconductor is used. The laser light emitted from the laser light source 203 is condensed by the condensing optical system 205 and reaches the laser plasma light source 207 disposed below. The laser plasma light source 207 can efficiently generate extreme ultraviolet light having a wavelength of about 13 nm.
[0035]
Xenon gas is supplied from a nozzle (not shown) to the laser plasma light source 207, and the xenon gas receives high illuminance laser light in the laser plasma light source 207. The xenon gas is heated to a high temperature by the irradiation of the laser light with high illuminance to excite the plasma state, and then emits extreme ultraviolet light when transitioning to a low potential state. Since the extreme ultraviolet light has a low transmittance to the atmosphere, the light source unit and the subsequent optical path are housed in a vacuum chamber 209.
[0036]
Above the laser plasma light source 207, a rotating parabolic mirror 211 on which a Mo / Si multilayer film is formed is arranged. The extreme ultraviolet light radiated from the laser plasma light source 207 is incident on the parabolic mirror 211, and only the extreme ultraviolet light having a wavelength of about 13 nm is reflected as parallel light toward the lower side of the exposure apparatus 201. Below the mirror 211, a visible light cut extreme ultraviolet light transmission filter 213 made of beryllium having a thickness of 0.15 nm is arranged. Of the extreme ultraviolet light reflected by the mirror 211, only the desired extreme ultraviolet light passes through the filter 213. The vicinity of the filter 213 is also covered by the chamber 215.
[0037]
An exposure chamber 233 is provided below the filter 213. An illumination optical system 217 is arranged below the filter 213 in the exposure chamber 233. The illumination optical system 217 includes a condenser-based mirror, a fly-eye optical-system mirror, and the like, shapes the extreme ultraviolet light incident from the filter 213 into an arc shape, and irradiates it toward the left in the drawing.
[0038]
On the left side of the drawing of the illumination optical system 217, an extreme ultraviolet light reflection mirror 219 is arranged. The mirror 219 has a disk shape in which the reflection surface 219a on the right side in the drawing has a concave shape. On the right side of the mirror 219 in the drawing, the optical path bending mirror 211 is disposed obliquely. Above the mirror 221, a reflection type mask 223 is horizontally arranged so that a reflection surface faces down. The extreme ultraviolet light emitted from the illumination optical system 217 is reflected and condensed by the extreme ultraviolet light reflection mirror 219, and then reaches the reflection surface of the reflection type mask 223 via the optical path bending mirror 221.
[0039]
Each of the mirrors 219 and 221 is made of a quartz substrate whose reflection surface is processed with high precision. On each mirror reflection surface, a multilayer film of Mo and Si having a high reflectance of 13 nm wavelength extreme ultraviolet light is formed. When extreme ultraviolet light having a wavelength of 10 to 15 nm is used, materials such as Ru (ruthenium) and Rh (rhodium), Si (silicon), Be (beryllium), ₄ It may be a multilayer film in combination with a substance such as C (carbon tetraboride).
[0040]
A reflection film made of a multilayer film is also formed on the reflection surface of the reflection type mask 223. A mask pattern corresponding to the pattern to be transferred to the wafer 229 is formed on the reflection film. The reflection type mask 223 is fixed to a mask stage 225 shown above. The mask stage 225 is movable in at least one direction, and irradiates the extreme ultraviolet light reflected by the optical path bending mirror 221 onto the mask 223 sequentially.
[0041]
Below the reflective mask 223, a projection optical system 227 and a wafer 229 are sequentially arranged. The projection optical system 227 includes a plurality of mirrors (for example, six). The projection optical system 227 reduces the pattern on the reflective mask 223 to a predetermined reduction ratio (for example, １ ／) and forms an image on the wafer 229. The wafer 229 is fixed to a wafer stage 231 that can move in the XYZ directions (see the drawing) by a suction means such as an electrostatic chuck.
[0042]
Next, the configuration of the mirror cooling device according to the present invention will be described with reference to FIGS.
FIG. 1 is a side view conceptually showing a mirror cooling device and one mirror according to one embodiment of the present invention.
[0043]
FIG. 2 is a bottom (partial) view of a mirror showing an example of arrangement of electronic cooling elements of the mirror cooling device.
FIG. 1 shows one mirror 1. The reflection surface 1a of the mirror 1 shown in this figure is an aspherical concave type, and has a multilayer film for reflecting desired EUV light as described above. The mirror 1 is used, for example, in the projection optical system 227 shown in FIG. A plurality of grooves 1c are arranged on the back surface 1b of the mirror 1. The groove 1c has a hexagonal shape as shown in FIG. 2, and a honeycomb structure is used to increase the rigidity of the mirror. In FIG. 1, the groove 1c is formed only on the back surface 1b of the mirror, but the groove 1c may be formed on the side surface 1d where the cell 2 is not located. The mirror side surface 1d is fixed via a spring-shaped member 3 by a cell 2 as a mirror holding member. The cell 2 is fixed to a lens barrel (not shown).
[0044]
An electronic cooling element (Peltier element) 4 is arranged corresponding to each of the grooves 1c. As shown in FIG. 2, each of the Peltier elements 4 is electrically connected to the control device 20 independently. The Peltier element 4 can be arranged not only on the back surface of the mirror but also on the side surface 1d and the front surface 1a. However, when it is arranged on the surface 1a, it is necessary to arrange so as not to block the incident and reflected light beams. A heat pipe 6 is connected to each Peltier element 4. The plurality of heat pipes 6 are combined into one heat pipe, and heat is discharged to the cooling mechanism 7 via the combined heat pipes. For example, the plurality of heat pipes 6 may be combined by being connected to an annular heat pipe (not shown) via a spring-like member.
[0045]
The Peltier element 4 is thermally connected to the groove 1c via a spring-like member 5 made of a leaf spring, a spring, or the like. The spring-like member 5 is made of a material having a small coefficient of thermal expansion, a high thermal conductivity, and a small amount of outgas. For example, Super Invar is used. The stiffness of the spring-like member 5 is low, so that a force is applied from the Peltier element 4 or the like during the assembly of the lens barrel and during the exposure operation to prevent the mirror from being deformed.
[0046]
The Peltier element 4 is fixed to a heat pipe 6, and the heat pipe 6 is fixed to the cell 2 with a heat insulating material 9 and a spring-like member 10 such as a leaf spring.
By the way, the heat insulating material 9 having a low thermal conductivity is preferable because it does not easily conduct heat. In particular, the thermal conductivity is 100 Jm ^-1 ・ K ^-1 When the content is below, the effect of using the heat insulating material becomes remarkable, which is preferable.
[0047]
Further, it is preferable that the heat insulating material does not adversely affect the degree of vacuum. Such materials include those described below.
First, an alloy made of Fe and Ni may be used as the metal material. Particularly, a ternary alloy of Ni-Cr-Fe and Fe-Ni-Co is preferable. More specifically, for example, an alloy having a composition ratio of Ni 72%, Cr 15%, and Fe 6% (Inconel 600) or an alloy having 52%, Ni 29%, and Co 17% (Kovar) is suitable.
[0048]
Further, as the ceramic material, metal oxides, carbides, nitrides, silicon oxides, and the like are preferable. More specifically, Ai ₂ O ₃ , TiC, SiC, ZrC, HfC, TaC, BN, TiN, AlN, SiO ₂ (Quartz) and the like. In addition, MgO.SiO, which is a silicon oxide ceramic, ₂ (Steatite), 3Al ₂ O ₃ ・ 2SiO ₂ (Mullite), ZrO ₂ ・ SiO ₂ (Zircon) and the like.
[0049]
Further, a material having a value close to the thermal expansion coefficient of the material of the lens barrel may be selected as the heat insulating material. For example, when invar or the like having a small coefficient of thermal expansion is used as the material of the lens barrel, quartz or low-thermal-expansion glass that also has a small coefficient of thermal expansion may be used as the heat insulating material.
[0050]
The heat insulating material 9 prevents the heat of the heat pipe 6 from being transmitted to the cells, thereby preventing the cells 2 from being deformed. Further, the spring-shaped member 10 prevents deformation and vibration of the heat pipe 6 from being transmitted to the cell 2. The spring-like member 10 can be made of a material having a low thermal conductivity and can be used instead of the heat insulating material 9. In this embodiment, the heat pipe 6 and the Peltier element 4 constituting the cooling device for cooling the mirror 1 are fixed to the cell 2, but they may be fixed to the lens barrel. The heat pipe 6 is fixed to a cooling mechanism 7 via a spring-like member 8. The cooling mechanism 7 was of a type that circulates water to cool the heat pipe. Further, the cooling mechanism 7 is connected to the control device 20 (not shown). The control device 20 controls an electric signal to be input to each Peltier element 4 and an electric signal to be input to the cooling mechanism 7 in accordance with a temperature distribution of the mirror determined in advance or measured in real time. Thus, the heat distribution of the mirror 1 is controlled to be uniform. The heat generated by the mirror 1 is discharged to the outside of the apparatus through the path of the Peltier device 4, the heat pipe 6, and the cooling mechanism 7.
[0051]
As for the above-mentioned constituent members that are arranged in a vacuum, it is preferable that a material that hardly generates outgas or contamination is used or a surface treatment is performed. Examples of the surface treatment include a high-temperature treatment and a method of coating a metal (such as TiN or NiP).
[0052]
FIG. 3 is a side view conceptually showing a mirror cooling device and one mirror according to another embodiment of the present invention.
In FIG. 3, the same components as those in the embodiment of FIG. This embodiment is different from the above-described embodiment in that the spring-like member 5 of FIG. 1 is removed in this embodiment, and all other configurations are the same as those of the embodiment of FIG. The heat from the mirror 1 propagates to the Peltier element 4 by radiation from the groove 1c and the like, and is discharged to the outside via a heat pipe 6 as a heat transfer element. In the present embodiment, since the Peltier element 4 and the mirror 1 are completely separated by removing the spring-like member 5, the force is transmitted from the Peltier element 4 to the mirror 1, and the deformation of the mirror 1 can be prevented.
[0053]
In this embodiment, the Peltier element 4 is arranged only on the back surface so that the description can be easily understood. However, it can be arranged on the side surface 1d and the front surface 1a.
FIG. 4 is a side view conceptually showing a mirror cooling device and one mirror according to another embodiment of the present invention.
[0054]
FIG. 4 is different from the embodiment of FIG. 3 in that gas is supplied, and the other configuration is the same as that of the embodiment shown in FIG. In FIG. 4, gas is supplied from the gas nozzle 43 to the groove 1 c of the mirror 1 from the gas supply device 41 via the gas pipe 42. The gas 40 that has passed through each groove 1c is discharged from a suction nozzle 44 via a gas pipe 45 by a pump 46. As the gas, a gas such as helium can be used, and plays a role of transmitting heat of the mirror 1 to the Peltier element 4. The gas discharged by the pump 46 can be recovered and brought to a desired temperature and then reused. If it is difficult to form a closed space between the heat pipe 6 and the Peltier element 4 alone and the back surface of the mirror 1, a wall, guard ring, or the like may be used to prevent the supplied gas from leaking into the vacuum chamber. Is preferably arranged. Further, in FIG. 4, the gas is supplied and discharged from the side, but the gas is not limited to the side, and the gas may be supplied and discharged from the bottom of the figure. Also, the number of gas nozzles and intake nozzles need not be limited to one, and a plurality of nozzles can be arranged.
[0055]
FIG. 5 is a side view conceptually showing a mirror cooling device and an exposure device according to another embodiment of the present invention.
In FIG. 5, a base 51 is fixed to a floor 50, and the base 51 penetrates a vacuum chamber 53 and supports a lens barrel 52 in the vacuum chamber 53 via a spring-like member 61. The vacuum chamber 53 is fixed to the floor by a member (not shown). The base 51 is connected to a vacuum chamber 53 via a flange 62 and a bellows 63, and is separated from the vacuum chamber 53. Therefore, the deformation of the vacuum chamber 53 during the evacuation is not transmitted to the base 51. A plurality of mirrors 1 and a plurality of heat pipes 6 for transmitting heat from each mirror are fixed to the lens barrel 52 so that vibration, deformation, and heat are not transmitted. The plurality of heat pipes 6 are connected to the second heat pipe 54 via a spring-like member 55. The second heat pipe 54 is fixed to the base 51 via a supporting member 60 and a heat insulating member 59 (the same material as described above can be used). Further, it is preferable to insert a spring because vibrations and changes in position are difficult to be transmitted. The second heat pipe 54 is connected to the vacuum chamber 53 via a flange 56, a heat insulating member 57 (similar to the above-described material), and a bellows 58, and thermally vibrates with the vacuum chamber 53.・ It is separated from the viewpoint of deformation. For example, the vacuum chamber 53, the flange 56, and the bellows 58 are made of a material such as stainless steel or a titanium alloy. The heat that has propagated through the second heat pipe 54 is transmitted to the cooling mechanism 7 via the spring-like member 8.
[0056]
Although not shown, the heat pipes 6 and 54 are covered with a heat insulating material except for a portion that is in thermal contact with another member (a portion connected to the spring-like member) in order to maintain desired performance. Is preferred. Since the influence of the heat pipe 54 on the mirror 1 is lower than that of the heat pipe 6, conditions such as vibration are alleviated. In that case, it is also possible to use a heat transfer element having a greater influence of vibration and the like than the heat pipe 54, and for example, a water-cooled pipe may be used.
[0057]
FIG. 6 is a side view conceptually showing a modification of the embodiment shown in FIG.
In FIG. 6, two heat pipes 71 and 72 are used instead of the second heat pipe 54 used in FIG. The heat pipe 71 is disposed in the vacuum chamber 53 and is connected to a flange 75 of the vacuum chamber 53 via a spring-like member 74. The heat pipe 72 is disposed outside the vacuum chamber 53 and has a spring-like member 73. Is connected to the flange 75 through the connection. The flange 75 is connected to the wall of the vacuum chamber 53 via the heat insulating member 58. The heat from each mirror 1 needs to be propagated in the order of the heat pipe 71, the spring member 74, the flange 75, the spring member 73, and the heat pipe 72. Therefore, the flange 75 is preferably made of a material having high thermal conductivity, for example, stainless steel. Alternatively, a heat pipe may be connected to this by embedding copper or the like having a higher thermal conductivity in the flange.
Other configurations are the same as those of the embodiment shown in FIG.
[0058]
【The invention's effect】
As is clear from the above description, according to the present invention, the mirror can be cooled to suppress the temperature rise, and the deformation and position change of the mirror can be suppressed. The effect of not performing is obtained.
[Brief description of the drawings]
FIG. 1 is a side view conceptually showing a mirror cooling device and one mirror according to one embodiment of the present invention.
FIG. 2 is a bottom (partial) view of a mirror showing an example of arrangement of electronic cooling elements of the mirror cooling device.
FIG. 3 is a side view conceptually showing a mirror cooling device and one mirror according to another embodiment of the present invention.
FIG. 4 is a side view conceptually showing a mirror cooling device and one mirror according to another embodiment of the present invention.
FIG. 5 is a side view conceptually showing a mirror cooling device and an exposure device according to another embodiment of the present invention.
FIG. 6 is a side view conceptually showing a modification of the embodiment shown in FIG.
FIG. 7 is a diagram illustrating an example of the overall configuration of an EUV light exposure apparatus.
FIG. 8 is a diagram showing a schematic configuration example of an EUV exposure apparatus.
FIG. 9 is a configuration diagram illustrating an example of an optical system barrel of the EUV light exposure apparatus.
[Explanation of symbols]
1 ... Mirror
2 ... cell (mirror holding member)
4 ・ ・ ・ Electronic cooling element
6 ... Heat transfer element
7 ... Cooling mechanism

Claims (15)

A mirror cooling device used in a vacuum,
An electronic cooling element for cooling the mirror,
A spring-like member disposed between the mirror and the electronic cooling element,
A heat transfer element that propagates heat exhausted from the electronic cooling element,
A cooling mechanism for cooling the heat transfer element,
A mirror cooling device, comprising: A mirror cooling device used in a vacuum,
An electronic cooling element arranged apart from the mirror,
A heat transfer element that propagates heat exhausted from the electronic cooling element,
A cooling mechanism for cooling the heat transfer element,
A mirror cooling device, comprising: The mirror cooling device according to claim 2, wherein
A gas supply mechanism for supplying gas between the electronic cooling element and the mirror;
A gas discharging mechanism for discharging the supplied gas,
A mirror cooling device, further comprising: A plurality of the electronic cooling elements are provided,
The mirror cooling device according to claim 1, further comprising a control device that independently controls each of the plurality of electronic cooling elements. The mirror cooling device according to claim 1, wherein a groove is provided in the mirror, and the mirror is cooled from a bottom surface of the groove. The mirror cooling device according to claim 1, wherein the heat transfer element is a heat pipe. The mirror cooling device according to claim 1, wherein the heat transfer element and a holding member that holds the mirror are connected via a spring-shaped member. The mirror cooling device according to claim 7, wherein a heat insulating member having a smaller thermal conductivity than the spring member is interposed between the spring member and the holding member. The mirror cooling device according to claim 1, wherein the heat transfer element and the cooling mechanism are connected via a spring-shaped member. An exposure apparatus comprising: an illumination optical system that guides a light beam emitted from a light source onto a reticle; and a projection optical system that projects an image of the reticle onto a sensitive substrate.
An exposure apparatus, wherein the illumination optical system and the projection optical system include a plurality of mirrors, and the cooling device according to any one of claims 1 to 9 is applied to at least one of the mirrors. An exposure apparatus having an optical system composed of a plurality of mirrors, wherein the optical system is disposed in a vacuum chamber, wherein a cooling element for cooling at least one of the plurality of mirrors, and a heat discharged from the cooling element A first heat transfer element for transmitting the heat, a second heat transfer element disposed through the wall of the vacuum chamber, and a spring-like member connecting the first heat transfer element and the second heat transfer element And a cooling mechanism for cooling the second heat transfer element. The exposure apparatus according to claim 11, wherein an elastic member is disposed between the second heat transfer element and the chamber wall. 13. The exposure apparatus according to claim 11, wherein a heat insulating member is arranged between the second heat transfer element and the chamber wall. An exposure apparatus having an optical system composed of a plurality of mirrors, wherein the optical system is disposed in a vacuum chamber, wherein a cooling element for cooling at least one of the plurality of mirrors, and a heat discharged from the cooling element , A second heat transfer element disposed inside the vacuum chamber, a third heat transfer element disposed outside the chamber, the first heat transfer element and the second heat transfer element. An exposure apparatus comprising: a first spring-like member that couples the first and second heat transfer elements; and a second spring-like member that couples the second heat transfer element and the third heat transfer element. . The exposure apparatus according to claim 1, wherein the second spring-like member comprises two spring-like members, and the two spring-like members are connected via a vacuum chamber.

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