Excimer lamps and light irradiation device

Abstract

To provide an excimer lamp that is configured to be implementable more simply, can reduce distortion occurring in an arc tube, and can be used for a longer period of time.SOLUTION: An excimer lamp includes an arc tube having translucency to ultraviolet light that extends in a first direction and has a first portion where the tube wall thereof is thinnest in a circumferential direction when a first section taken along a plane perpendicular to the first direction is viewed, a pair of electrodes that face each other via the tube wall of the arc tube in a radial direction of the arc tube, a light extraction section that includes at least the first portion of the tube wall of the arc tube and from which ultraviolet light generated inside the arc tube is extracted, and a reflecting member that reflects ultraviolet light traveling in a direction different from the light extraction section toward the light extraction section side. When the first cross section is viewed, the arc tube has an asymmetrical shape with respect to a tube axis between the tube wall on the light extraction section side and the tube wall on the opposite side to the light extraction section.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to an excimer lamp and a light irradiation device. [Background technology]

[0002] Conventionally, ultraviolet light has been used in the manufacture of semiconductors and liquid crystal panels, and in the generation of ozone for air purification. For example, an excimer lamp as described in the following Patent Document 1 is used as a light source for emitting ultraviolet light. The following Patent Document 1 discloses an excimer lamp in which a reflective film is formed on the inner wall surface of the arc tube in order to efficiently irradiate an object to be irradiated with ultraviolet light emitted from the arc tube. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5633354 Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, there has been a demand for higher output excimer lamps as industrial light irradiation devices used in the manufacture of semiconductors and liquid crystal panels, etc. Therefore, the present inventors have investigated ways to increase the output of excimer lamps based on the light irradiation device described in the above Patent Document 1, and have found that the following problems exist. The following will be explained with reference to the drawings.

[0005] Fig. 9A is a schematic diagram of the configuration of a conventional excimer lamp 100 when viewed in the Y direction. Fig. 9B is a schematic diagram of the excimer lamp 100 of Fig. 9A when viewed in the Z direction. As shown in Figs. 9A and 9B, the excimer lamp includes an arc tube 101, a pair of electrodes 102 provided to face an outer wall surface 101a of the arc tube 101, and a reflective film 103 provided on an inner wall surface 101b of the arc tube 101.

[0006] 9A, the direction in which the arc tube 101 of the excimer lamp 100 extends (tube axis direction) is defined as the X direction, the direction in which the electrodes 102 face each other is defined as the Z direction, and the direction perpendicular to the X direction and the Z direction is defined as the Y direction. When expressing a direction, if a distinction is made between positive and negative directions, the direction is described with a positive or negative sign added, such as "+Z direction" and "-Z direction," and when expressing a direction without distinguishing between positive and negative directions, the direction is simply described as "Z direction."

[0007] Arc tube 101 is made of a material (e.g., silica glass) that is transparent to ultraviolet light, and has a light-emitting space 101c formed inside in which light-emitting gas G1 is sealed. As shown in Fig. 9B, electrode 102 is formed in a mesh shape so that ultraviolet light emitted from arc tube 101 can be extracted to the outside of arc tube 101. Note that, although only electrode 102 on the +Z side is shown in Fig. 9B, electrode 102 on the -Z side has the same shape as electrode 102 on the +Z side.

[0008] In the excimer lamp 100, ultraviolet light is generated in the light-emitting space 101c by applying a voltage between the pair of electrodes 102, and the ultraviolet light is emitted outward from the mesh of the electrodes 102. The type and combination of the light-emitting gas G1 to be sealed in the light-emitting space 101c are selected according to the wavelength of the emitted ultraviolet light.

[0009] Ultraviolet light of 200 nm or less, such as that used in the manufacture of semiconductors and liquid crystal panels, can break the bonds between Si and O in the silica glass that is the material of the arc tube 101. Therefore, when the excimer lamp 100 is turned on, the ultraviolet light emitted from the light-emitting space 101c breaks the bonds of the silica glass that constitutes the arc tube 101 one after another, changing the bond angle between Si and O and causing distortion.

[0010] When the excimer lamp 100 is turned on, the tube wall on the light emission surface 104 side (-Z side) of the arc tube 101 is constantly exposed to ultraviolet light emitted from the light emission space 101c. On the other hand, the tube wall on the opposite side (+Z side) of the light emission surface 104 of the arc tube 101 is hardly exposed to ultraviolet light because the ultraviolet light emitted from the arc tube 101 is reflected toward the light emission surface 104 side by the reflective film 103 formed on the inner wall surface 101b. In such a tube wall on the -Z side, compressive strain occurs due to irradiation with ultraviolet light, and the structure changes and the volume of the tube wall shrinks. On the other hand, since no strain occurs due to irradiation with ultraviolet light in the tube wall on the +Z side, the entire arc tube is deformed to be convex toward the +Z side.

[0011] Fig. 10 is a drawing of the excimer lamp 100 deformed by ultraviolet light when viewed in the Y direction. The ultraviolet light emitted from the light-emitting space 101c causes the arc tube 101 to deform as described above, and as shown in Fig. 10, the arc tube 101 deforms so that the entire tube becomes convex toward the +Z side in accordance with the deformation of the wall surface on the -Z side. When the arc tube 101 deforms, the distance between the light exit surface 104 and the irradiation area varies depending on the position, resulting in uneven irradiation. Note that the excimer lamp 100 in Fig. 10 is depicted as being more deformed than it actually is, in order to make the change easier to understand.

[0012] The above-mentioned Patent Document 1 discloses an excimer lamp having an arc tube that is curved in advance so that distortion caused by irradiation with ultraviolet light causes the wall surface of the arc tube to become nearly flat, in order to prevent uneven irradiation of ultraviolet light due to deformation of the arc tube and damage to the arc tube 101.

[0013] However, it is difficult to accurately predict the degree of distortion that will occur due to irradiation with ultraviolet light, and advanced processing techniques are required to bend the arc tube to the desired curvature during the manufacturing process.

[0014] In the above explanation, the explanation is based on the excimer lamp 100 provided with the reflective film 103, but naturally, deformation of the arc tube 101 due to irradiation with ultraviolet light can also occur in an excimer lamp that is not provided with the reflective film 103. In other words, the pattern of deformation that occurs in the arc tube 101 differs depending on whether the reflective film 103 is provided or not, but in either case, deformation occurs in the arc tube 101 due to irradiation with ultraviolet light. For this reason, the problem of uneven irradiation can also occur in an excimer lamp that is not provided with the reflective film 103.

[0015] Furthermore, the above-mentioned problem also exists in that the direction and part of the arc tube 101 that deforms differs depending on the respective device configurations, such as when a reflective member is provided on the outside of the arc tube 101 or when a cooling mechanism is provided.

[0016] In view of the above problems, an object of the present invention is to provide an excimer lamp and a light irradiation device that can be used for a longer period of time by reducing distortion caused in an arc tube with a configuration that can be more simply implemented. [Means for solving the problem]

[0017] The excimer lamp of the present invention is an arc tube that is elongated in a first direction and has a first portion in which a tube wall is thickest in a circumferential direction when viewed in a first cross section when cut along a plane perpendicular to the first direction; a pair of electrodes facing each other in a radial direction of the arc tube via a tube wall of the arc tube; a light extraction section including at least the first portion of a tube wall of the light emitting tube, through which ultraviolet light generated within the light emitting tube is extracted; a reflecting member that reflects ultraviolet light traveling in a direction different from the light extraction portion toward the light extraction portion, The arc tube is characterized in that, when viewed in the first cross section, a tube wall on the side of the light extraction portion and a tube wall on the opposite side to the light extraction portion are asymmetric in shape with respect to the tube axis.

[0018] As mentioned above, the distortion of the arc tube caused by irradiation with ultraviolet light is caused by the breaking of the Si-O bonds in the silica glass. However, it is known that the Si-O bonds broken by irradiation with ultraviolet light are recombined due to the repair action of the OH groups contained in the silica glass. Furthermore, this repair action becomes more pronounced the higher the temperature of the silica glass and the more active the internal atomic movement. In other words, the higher the temperature of the arc tube, the more pronounced the repair action effect of the OH groups becomes, and the distortion caused by the breakage of Si-O is alleviated.

[0019] A light emitting tube having a thick wall in a portion thereof accumulates a larger amount of heat than a light emitting tube having a uniform thickness without any thick wall in a portion thereof, and thus has an improved heat retention effect. Therefore, a light emitting tube having a thick wall in a portion thereof maintains a high temperature state for a longer period even after the light is turned off, and the above-mentioned repair effect continues for a long period of time. In other words, a light emitting tube having this configuration is more likely to return to the state before the distortion occurred, compared to a light emitting tube having a conventional configuration, even if distortion occurs due to irradiation with ultraviolet light.

[0020] For example, if the downtime of an excimer lamp (the time from when the lamp is turned off until it is turned back on) is relatively short and the lamp is repeatedly turned on again before the temperature of the light-emitting tube returns to room temperature, then if the light-emitting tube has some areas with thick walls when the on-off operation is repeated in a short period of time, distortion is less likely to occur because the heat-retaining effect continues.

[0021] It is possible to thicken the entire wall of the arc tube in order to obtain a higher heat retention effect, but if the wall of the entire arc tube is thickened, the excimer lamp itself will become unnecessarily large, and the manufacturing costs will also increase.

[0022] In addition, since the reflecting member side of the excimer lamp is located on the opposite side to the workpiece, it is relatively easy to provide a separate heater, but it is difficult to provide a separate heater on the light extraction part side of the excimer lamp due to concerns about impeding the progress of ultraviolet light toward the workpiece and thermal damage to the workpiece. For this reason, there is also a circumstance in which the wall surface on the light extraction part side of the arc tube is less likely to promote the above-mentioned repair action effect than the wall surface on the reflecting member side.

[0023] With the above-mentioned configuration, it is possible to enhance the repair effect on the wall surface on the light emission surface side of the light emitting tube by increasing the size to the minimum necessary without providing a separate heater or the like.

[0024] Furthermore, when the thickness of the tube wall differs, the stress is different when the light-emitting tube is distorted. Therefore, if there is a part where the thickness of the tube wall changes abruptly, the boundary part is likely to become the starting point of cracks, etc.

[0025] Therefore, the distortion occurring in the light emitting tube is reduced compared to the conventional case, and an excimer lamp that can be used for a longer period of time is realized.

[0026] According to the above-mentioned configuration, the portion of the arc tube where the stress caused by distortion changes abruptly is alleviated, so that the arc tube is less likely to break.

[0027] The above excimer lamps are The first cross section of the arc tube may have a rectangular shape, and the light extraction portion may be formed on one of the wall surfaces of the arc tube that are aligned along different planes.

[0028] Furthermore, in the above excimer lamp, The light extraction portion may have a wall surface with a substantially uniform thickness.

[0029] In this specification, "having substantially the same thickness" means that the error in the average thickness of the tube wall in the first cross section is within ±3%.

[0030] According to the above-mentioned configuration, the heat retention effect of the entire light extraction section is improved, so that the above-mentioned repair effect is more effective in the light extraction section which is irradiated with a larger amount of ultraviolet light.

[0031] In the above excimer lamp, The reflecting member may be a reflecting film formed on the inner wall surface of the light emitting tube.

[0032] Furthermore, in the above excimer lamp, The light extraction portion may be formed so that the vicinity of the end portion of the reflective film is thicker than the central portion in the circumferential direction when viewed in the first cross section.

[0033] The light extraction section is irradiated with ultraviolet light, so distortion occurs more significantly, but the area where the reflective film is formed does not experience as much distortion as the light extraction section, because less ultraviolet light is irradiated onto the light-emitting tube itself. In areas where distortion occurs, the shape of the tube wall is prone to change. As a result, the area near the end of the reflective film is the boundary between areas where distortion occurs and areas where distortion is unlikely to occur, so it is prone to localized strong stress and breakage.

[0034] Furthermore, when the tube wall corresponding to the light extraction portion of the arc tube is fabricated or processed so that the reflective film is thicker near the ends than in the center, the above-mentioned repair effect is more effective for a long time in the area that is likely to be locally subjected to strong stress, and therefore the load generated in that area of ​​the arc tube can be further reduced.

[0035] For example, the first cross section is flattened, and the vicinity of the end of the reflective film is the boundary between an area where distortion occurs and an area where distortion is unlikely to occur, so that it is likely to be locally subjected to stronger stress and become the starting point of breakage. In particular, when the output of the excimer lamp is high, a difference in the amount of distortion is likely to occur, and local loads at the boundary portion are likely to become a problem. Therefore, from the viewpoint of strengthening the resistance to loads at the boundary portion between the area where distortion is likely to occur and the area where distortion is unlikely to occur due to the high output of the excimer lamp, it is desirable to form the vicinity of the end of the reflective film to be thicker than the central portion. In addition, by forming an area where the tube wall is thick, the heat retention effect can be improved.

[0036] Furthermore, in the case of the above configuration, with respect to the light extraction section, the difference in thickness between the part where the tube wall is thinnest and the part where the tube wall is thickest is preferably 3% or more based on the thickness of the part where the tube wall is thickest, more preferably 5% or more, and even more preferably 10% or more.

[0037] In the above excimer lamp, The light extraction portion may be formed so that a central portion is thicker than an end portion of the reflective film in a circumferential direction when viewed in the first cross section.

[0038] When the tube wall is manufactured or processed so that the central part of the light extraction part is thicker than the end part of the reflective film in the circumferential direction when the first cross section is viewed, the amount of heat accumulated in the light emitting tube is greater, so that the heat retention effect of the central part of the light extraction part can be improved and the central part of the light extraction part can easily reach a higher temperature. In other words, the light emitting tube of the above configuration can obtain a higher effect of the repair action for a long period of time in the part where distortion is relatively likely to occur. Therefore, distortion of the entire light emitting tube can be further reduced.

[0039] In addition, an excimer lamp has a light emitting gas, including xenon (Xe) gas, sealed in the light emitting tube, and the inside of the light emitting tube is under negative pressure. For example, the first cross section is flat, and the negative pressure tends to increase the stress in the center of the light extraction part (the center of the light extraction part is easily subjected to a load). When the output of the excimer lamp is high, the degree of negative pressure in the light emitting tube is reduced, but when the output of the excimer lamp is low, the load on the center of the light extraction part is relatively large. Therefore, from the viewpoint of strengthening the resistance of the center of the light extraction part to the load, it is desirable to form the tube wall in the center of the light extraction part so that it is thicker than the vicinity of the end of the reflective film. Also, forming an area with a thick tube wall can enhance the heat retention effect.

[0040] Furthermore, in the case of the above configuration, with respect to the light extraction section, the difference in thickness between the part where the tube wall is thinnest and the part where the tube wall is thickest is preferably 3% or more based on the thickness of the part where the tube wall is thickest, more preferably 5% or more, and even more preferably 10% or more.

[0041] Furthermore, according to the above configuration, the arc tube has irregularities due to changes in thickness, which improves its strength against deformation caused by bending in the first direction due to distortion caused by ultraviolet light irradiation. Therefore, the arc tube of the above configuration is less likely to deform due to ultraviolet light irradiation than arc tubes of conventional configurations.

[0042] The above excimer lamps are The first cross section of the arc tube may have a circular shape.

[0043] The light irradiation device of the present invention comprises: The above excimer lamp, The light emitting device is characterized in that it further comprises a restricting body that protrudes toward a tube wall that faces the light extraction portion of the light emitting tube and is disposed so that a tip portion thereof is adjacent to the tube wall.

[0044] In this specification, the term "close proximity" is used to mean a separation distance of 2 mm or less. Effect of the Invention

[0045] According to the present invention, it is possible to realize an excimer lamp and a light irradiation device that can be used for a longer period of time by reducing distortion occurring in the light emitting tube with a configuration that can be more simply implemented. [Brief description of the drawings]

[0046] [Figure 1] 2 is a schematic cross-sectional view of an embodiment of a light irradiation device when viewed in the Y direction. FIG. [Diagram 2] 2 is a schematic cross-sectional view of an excimer lamp according to an embodiment when viewed in the Y direction. [Diagram 3] 1 is a schematic diagram of an excimer lamp according to an embodiment when viewed in the Z direction. [Figure 4] 2 is a schematic cross-sectional view of an excimer lamp according to an embodiment when viewed in the X direction. [Diagram 5] 11 is an enlarged cross-sectional view of the periphery of a regulating body of the light irradiation device as viewed in the X direction. FIG. [Figure 6] 13 is a schematic cross-sectional view of an excimer lamp according to another embodiment when viewed in the X direction. FIG. [Figure 7] 13 is a schematic cross-sectional view of an excimer lamp according to another embodiment when viewed in the X direction. FIG. [Figure 8A] 13 is a schematic cross-sectional view of an excimer lamp according to another embodiment when viewed in the Y direction. FIG. [Figure 8B] 8B is a schematic cross-sectional view of the excimer lamp of FIG. 8A when viewed in the X direction. [Figure 9A] 1 is a schematic diagram showing the configuration of a conventional excimer lamp as viewed in the Y direction. [Figure 9B] 9B is a schematic diagram of the excimer lamp of FIG. 9A when viewed in the Z direction. [Figure 10] This is a drawing of an excimer lamp deformed by ultraviolet light, viewed in the Y direction. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0047] The excimer lamp and the light irradiation device of the present invention will be described below with reference to the drawings. Note that the drawings are all schematic illustrations, and the dimensional ratios and numbers in the drawings do not necessarily match the actual dimensional ratios and numbers.

[0048] Fig. 1 is a schematic cross-sectional view of an embodiment of a light irradiation device 1 as viewed in the Y direction. As shown in Fig. 1, the light irradiation device 1 of this embodiment includes an excimer lamp 2, a regulating body 3, and a transport mechanism 4 on which an irradiation target W1 is placed.

[0049] First, the configuration of the excimer lamp 2 will be described. Fig. 2 is a schematic cross-sectional view of the excimer lamp 2 in one embodiment when viewed in the Y direction. Fig. 3 is a schematic drawing of the excimer lamp 2 in one embodiment when viewed in the Z direction. Fig. 4 is a schematic cross-sectional view of the excimer lamp 2 in one embodiment when viewed in the X direction. As shown in Figs. 2 and 4, the excimer lamp 2 includes an arc tube 10, a pair of electrodes (11, 12), a reflective film 13, and a light extraction portion 14.

[0050] 2, the direction in which the excimer lamp 2 extends (tube axis direction) is the X direction (first direction), the direction in which the pair of electrodes (11, 12) face each other is the Z direction, and the direction perpendicular to the X direction and Z direction is the Y direction (second direction). When expressing a direction, if positive and negative directions need to be distinguished, the direction is described with a positive and negative sign, such as "+Z direction" and "-Z direction," and when expressing a direction without distinguishing between positive and negative directions, the direction is simply described as "Z direction."

[0051] The light emitting tube 10 is made of a material (e.g., silica glass) that is translucent to the ultraviolet light L1, and extends in the X direction, and has a rectangular shape when cut in the YZ plane (first cross section) as shown in Fig. 2. The light emitting tube 10 is provided with a light emitting space 10c inside which a light emitting gas G1 is sealed.

[0052] In the excimer lamp 2 in this embodiment, a light emitting gas G1 containing xenon (Xe) gas is sealed in the light emitting space 10c of the light emitting tube 10 so as to emit ultraviolet light L1 with a peak wavelength of 172 nm. Note that this configuration is merely an example, and the type of light emitting gas G1 sealed in the light emitting tube 10 is arbitrarily selected according to the purpose of use of the light irradiation device 1, i.e., the wavelength of the ultraviolet light L1 to be emitted.

[0053] The electrodes (11, 12) are mesh-like metal films formed on the outer wall surface 10a of the arc tube 10 in the Z direction so as to face each other via the arc tube 10, and are connected to a power supply device (not shown) to apply a voltage required for lighting. Any method for applying the voltage may be used, but in this embodiment, a pulsed voltage of a desired level is periodically applied between the electrodes (11, 12) to generate ultraviolet light L1 in the light-emitting space 10c.

[0054] The electrodes (11, 12) are, for example, metal wires woven into a mesh shape, or metal films formed by evaporating a metal material onto the masked outer wall surface 10a of the arc tube 10. The electrode 11 formed on the outer wall surface 10a of the tube wall on which the reflective film 13 is formed does not need to be in the form of a mesh, and may be a solid electrode over a portion or the entirety.

[0055] The electrodes (11, 12) are made of a material such as gold, silver, copper, or platinum.

[0056] The reflective film 13 is formed on the inner wall surface 10b of the tube wall on the +Z side of the light emitting tube 10 and on the inner wall surface 10b of the tube wall opposing the +Z side in the Y direction. As shown in Fig. 4, the reflective film 13 reflects the ultraviolet light L1 that is generated in the light emitting space 10c and travels in a direction different from the light extraction part 14 so that the ultraviolet light L1 travels toward the light extraction part 14.

[0057] The reflective film 13 may be a metal oxide film formed by applying a suspension containing particulate silica (SiO2), alumina (Al2O3), or the like, and baking the suspension.

[0058] The light extraction section 14 is a part of the arc tube 10 that is configured by the tube wall on the -Z side of the arc tube 10 and that extracts the ultraviolet light L1 generated in the light-emitting space 10c to the outside of the arc tube 10. Note that the light extraction section 14 in this embodiment is provided with a mesh-shaped electrode 12 as shown in Fig. 3. Therefore, the ultraviolet light L1 generated in the light-emitting space 10c of the arc tube 10 is emitted to the outside of the arc tube 10 via the light extraction section 14 and the mesh of the electrode 12.

[0059] As shown in Fig. 4, the light extraction section 14 is thicker than the tube wall having the reflective film 13 provided on the inner wall surface 10b, and is formed of a tube wall having substantially the same thickness. That is, the light extraction section 14 in this embodiment corresponds substantially entirely to the first part 14a, which is the thickest part of the tube wall. The difference between the thickness of the light extraction section 14 and the thickness of the tube wall other than the light extraction section 14 is preferably 3% or more, more preferably 5% or more, and even more preferably 10% or more, of the thickness of the tube wall other than the light extraction section 14.

[0060] The arc tube 10 in this embodiment is configured so that the thickness of the light extraction portion 14 is 3.0 mm, and the thickness of the tube wall other than the light extraction portion 14 is 2.5 mm (i.e., the difference between the thickness of the light extraction portion 14 and the thickness of the tube wall other than the light extraction portion 14 is 20%). That is, the arc tube 10 in this embodiment is configured so that, as viewed from the tube axis Ax, the shape of the tube wall on the light extraction portion 14 side (-Z side) and the shape of the tube wall on the opposite side to the light extraction portion 14 (+Z side) are asymmetric. The thickness of the tube wall of the light extraction portion 14 does not have to be approximately uniform throughout, as long as it is formed to be thicker than the other wall surfaces.

[0061] Furthermore, as shown in FIG. 4, at both ends of the light extraction portion 14 in the Y direction, i.e., near the end 13a of the reflective film 13, a displacement region 10p (a portion surrounded by a dashed line) is formed in which the thickness of the tube wall of the light-emitting tube 10 gradually changes.

[0062] Fig. 5 is an enlarged cross-sectional view of the periphery of the regulating body 3 of the light irradiation device 1 as viewed in the X direction. As shown in Fig. 5, the regulating body 3 protrudes so as to approach the arc tube 10. A roller 3a is provided at the tip, and the roller 3a is disposed so as to be in close proximity to the tube wall on the +Z side. When distortion as shown in Fig. 10 occurs, the roller 3a comes into contact with the arc tube 10 to regulate the distortion from becoming larger, thereby suppressing damage to the arc tube 10.

[0063] In the light irradiation device 1 of this embodiment, a plurality of regulating bodies 3 may be provided in one light irradiation device 1, and the tip portion where the roller 3a is provided may be bifurcated, or may be trifurcated or more. According to this configuration, the excimer lamp 2 in which distortion has occurred is supported at a plurality of points. Therefore, in the light irradiation device 1 with this configuration, the force applied to the arc tube 10 is dispersed compared to the case where it is supported at one point, and damage to the arc tube 10 is suppressed.

[0064] The excimer lamp 2 included in the light irradiation device 1 configured as above can enhance the heat retention effect of the light extraction part 14, which is irradiated with a relatively large amount of ultraviolet light L1. In other words, the arc tube 10 configured as above has a configuration in which the effect of the above-mentioned repair action is relatively enhanced in the parts relatively prone to distortion, so that distortion of the entire arc tube can be further reduced.

[0065] [Another embodiment] Another embodiment will be described below.

[0066] <1> Fig. 6 is a schematic cross-sectional view of an excimer lamp 2 in another embodiment when viewed in the X direction. As shown in Fig. 6, the light extraction portion 14 of the excimer lamp 2 may be formed so that the vicinity of the end 13a of the reflective film 13 is thicker than the central portion in the circumferential direction when viewed in a first cross section. In other words, the first portion 14a may be formed on both ends in the Y direction of the wall surface on the -Z side. Also, as shown in Fig. 6, a displacement region 10p is formed in which the thickness of the tube wall of the arc tube 10 gradually changes.

[0067] When the tube wall corresponding to the light extraction portion 14 of the arc tube 10 is fabricated or processed so that the vicinity of the end portion 13a of the reflective film 13 is thicker than the central portion, the above-mentioned repair effect is more effective for a long time in the region that is likely to be subjected to localized strong stress. Therefore, the load generated in that region of the arc tube 10 can be further reduced.

[0068] Fig. 7 is a schematic cross-sectional view of an excimer lamp 2 in another embodiment different from that in Fig. 6, as viewed in the X direction. As shown in Fig. 7, the light extraction portion 14 of the excimer lamp 2 may be formed so that, in the circumferential direction when viewed in the first cross section, the central portion is thicker than the vicinity of the end portion 13a of the reflective film 13. Also, as shown in Fig. 7, a displacement region 10p is formed in which the thickness of the tube wall of the arc tube 10 gradually changes.

[0069] When the tube wall in the center of the light extraction portion is manufactured or processed so as to be thicker in the circumferential direction when viewed from the first cross section than in the vicinity of the end 13a of the reflective film 13, the arc tube 10 can enhance the heat retention effect of the center of the light extraction portion 14 where the amount of irradiation of the ultraviolet light L1 is relatively large, and the center of the light extraction portion 14 can easily reach a higher temperature. In other words, the arc tube 10 configured as described above can obtain a higher effect of the repair action for a long period of time in the portion where distortion is relatively likely to occur. Therefore, distortion of the entire arc tube 10 can be further reduced.

[0070] With respect to the light extraction section 14, the difference between the thickness of the part where the tube wall is thinnest and the thickness of the part where the tube wall is thickest is preferably 3% or more, more preferably 5% or more, and even more preferably 10% or more, based on the thickness of the part where the tube wall is thickest.

[0071] <2> In each of the above-described embodiments, a configuration has been described in which the shape of the first cross section of the arc tube 10 is rectangular. However, the shape of the first cross section of the arc tube 10 does not have to be rectangular and may be, for example, a circular, oval, elliptical, polygonal, or any other shape.

[0072] Fig. 8A is a schematic cross-sectional view of an excimer lamp 2 in another embodiment when viewed in the Y direction, and Fig. 8B is a cross-sectional view of the excimer lamp 2 in Fig. 8A when viewed in the X direction. Note that Fig. 8A illustrates a state in which a reflecting member 81 has been removed for the convenience of illustrating the shape of the excimer lamp 2. As shown in Figs. 8A and 8B, the excimer lamp 2 may be a lamp of a type also called a double-tube shape, which includes an arc tube 80 consisting of an outer tube 80a and an inner tube 80b, and in which one electrode 11 is provided on the inner wall surface of the inner tube 80b and the other electrode 12 is provided on the outer wall surface of the outer tube 80a, so that the pair of electrodes (11, 12) face each other in the radial direction of the outer tube 80a, which corresponds to the arc tube.

[0073] As shown in Fig. 8B, in the excimer lamp 2 of this embodiment, the outer wall surface 80c and the inner wall surface 80d of the outer tube 80a are eccentric. Note that, for the sake of explanation, Fig. 8B illustrates a state in which the outer wall surface 80c and the inner wall surface 80d of the outer tube 80a are extremely eccentric.

[0074] As shown in Fig. 8B, the excimer lamp 2 in this embodiment is provided with a reflecting member 81 disposed adjacent to the +Z side of the outer tube 80a. The reflecting member 81 has a reflecting surface 81a that reflects, to the -Z side, the ultraviolet light L1 that is generated in the space between the outer tube 80a and the inner tube 80b and travels toward the +Z side. The reflecting member 81 is, for example, a member made by bending an aluminum plate or a PTFE plate. The reflecting member 81 may be provided with a hole for inserting the regulating body 3 shown in Fig. 5 therethrough.

[0075] In this shape, the wall surface on the -Z side, which includes the thickest part of the tube wall of the outer tube 80a and where the reflective member 81 is not arranged, constitutes the light extraction section 14. Note that the first portion 14a in this configuration is the wall surface located on the -Z side as viewed from the tube axis.

[0076] In this embodiment, the outer wall surface 80c and the inner wall surface 80d of the outer tube 80a are eccentric to change the tube wall thickness, i.e., the entire outer tube 80a is configured to be a displacement region, but the configuration for changing the tube wall thickness is not limited to this configuration. For example, the outer tube 80a may be configured so that the thickness is changed by polishing, cutting, deforming, or additionally depositing the same material on the outer wall surface 80c after the outer tube 80a is created so that the outer wall surface 80c and the inner wall surface 80d are concentric.

[0077] <3> The configurations of the light irradiation device 1 and the excimer lamp 2 described above are merely examples, and the present invention is not limited to the configurations shown in the drawings. [Explanation of symbols]

[0078] 1 : Light irradiation device 2: Excimer lamp 3: Regulatory body 3a: Laura 4: Transport mechanism 10: Arc tube 10a: Exterior wall 10b: Inner wall 10c: Luminous Space 10d : Boundary 10p : Displacement area 11,12 : Electrode 13: Reflective film 13a: End 14: Light extraction section 14a : first part 80: Arc tube 80a : Outer tube 80b : Inner tube 80c: External wall surface 80d: Inner wall 81: Reflective material 81a : Reflective surface 100: Excimer lamp 101: Arc tube 101a: External wall surface 101b: Inner wall 101c: Luminous space 102 : Electrode 103 : Reflective film 104: Light exit surface Ax: Tube axis G1: Luminous gas L1: Ultraviolet light W1: Irradiation target

Claims

1. an arc tube that is elongated in a first direction and has a first portion in which a tube wall is thickest in a circumferential direction when viewed in a first cross section when cut along a plane perpendicular to the first direction; a pair of electrodes facing each other in a radial direction of the arc tube via a tube wall of the arc tube; a light extraction section including at least the first portion of a tube wall of the light emitting tube, through which ultraviolet light generated within the light emitting tube is extracted; a reflecting member that reflects ultraviolet light traveling in a direction different from the light extraction portion toward the light extraction portion, The excimer lamp is characterized in that, when viewed in the first cross section, the shape of a tube wall on the side of the light extraction portion and the shape of a tube wall on the opposite side to the light extraction portion are asymmetric with respect to the tube axis.

2. 2. The excimer lamp according to claim 1, wherein the shape of the first cross section of the light-emitting tube is rectangular, and the light extraction portion is formed on one of the wall surfaces of the light-emitting tube that are aligned along different planes.

3. 3. The excimer lamp according to claim 2, wherein the light extraction portion has a wall surface having a substantially uniform thickness.

4. 3. The excimer lamp according to claim 2, wherein the reflecting member is a reflecting film formed on an inner wall surface of the light emitting tube.

5. 5. The excimer lamp according to claim 4, wherein the light extraction portion is formed so as to be thicker near the ends of the reflective film than at a central portion in a circumferential direction when viewed in the first cross section.

6. 5. The excimer lamp according to claim 4, wherein the light extraction portion is formed so that a center portion thereof is thicker than an end portion of the reflective film in a circumferential direction when viewed in the first cross section.

7. 2. The excimer lamp according to claim 1, wherein the first cross section of the arc tube has a circular shape.

8. An excimer lamp according to any one of claims 1 to 7, a regulating body that protrudes toward a tube wall located on the opposite side of the light extraction portion of the light-emitting tube and is arranged so that a tip portion thereof is adjacent to the tube wall.

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