Excimer lamp, excimer lamp lighting method, and excimer lamp manufacturing method

Abstract

To provide an excimer lamp that lights efficiently while improving the lighting start-up of the lamp.SOLUTION: An excimer lamp 10 includes an outer tube 20 and an inner tube 50 arranged coaxially in the outer tube 20. The inner tube 50 covers an inner electrode 30. A main discharge space S1 is formed between the outer tube 20 and the inner tube 50. A discharge space for lighting start-up assistance (hereinafter referred to as "auxiliary discharge space") S2 is formed between the inner electrode 30 and the inner tube 50.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an excimer lamp, and more particularly to the operation of an excimer lamp. [Background technology]

[0002] A double-tube structure lamp is known as a configuration of an excimer lamp (see Patent Document 1). In this lamp, a dielectric covering a foil-shaped inner electrode is placed inside a discharge tube, and a voltage is applied between an outer electrode provided on the outer surface of the discharge tube and an inner electrode provided inside the discharge tube. This causes excimer light such as ultraviolet light to be emitted from the discharge space formed between the dielectric and the discharge tube.

[0003] Discharge tubes made of quartz glass deteriorate due to ultraviolet radiation when lamps are lit for long periods of time, and in some cases, the discharge tube may break. However, it is difficult to determine from appearance whether a lamp is nearing the end of its life. For this reason, a method has been proposed in which an IC tag is attached to each lamp, and the accumulated lighting time and the lamp's specific electrical characteristics (initial power, etc.) are recorded and managed (see Patent Document 2). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-38658 [Patent Document 2] Japanese Patent Application Laid-Open No. 2010-027944 Summary of the Invention [Problem to be solved by the invention]

[0005] It is difficult to manage lamp life as described above for portable ozone generators and other devices that are used in a variety of environments and sold and distributed to unspecified users. Furthermore, it is not easy to manage lamp life as described above in environments where excimer lamps are used in production sites, such as for photoresist curing and substrate cleaning in semiconductor manufacturing processes.

[0006] Therefore, it is necessary to provide an excimer lamp that can be turned off before the discharge tube becomes weak at the end of the lamp's life. [Means for solving the problem]

[0007] The excimer lamp of the present invention comprises a dielectric covering foil electrodes arranged along the lamp axis, and a discharge vessel that is welded to the dielectric to form a main discharge space, and the foil electrodes are partially sealed to the dielectric so that an auxiliary discharge space is formed inside the dielectric, and a film (hereinafter referred to as a shielding film) that suppresses the transmission of electromagnetic waves is formed on at least a portion of the inner surface of the dielectric that is exposed to the auxiliary discharge space by the discharge in the auxiliary discharge space.

[0008] Here, "electromagnetic waves" includes ultraviolet rays, light including ultraviolet wavelengths, light including visible light wavelengths that humans perceive as light, and electromagnetic waves generated in areas where electric fields are generated. Furthermore, "suppress" refers to lowering transmittance, functioning to reduce transmittance, or functioning like an electromagnetic shield in a spatial area where an electric field is concentrated, thereby rendering the ultraviolet radiation and electric field strength necessary for transitioning to rated lighting insufficient. For example, a shielding film that suppresses rated lighting due to discharge in the main discharge space, in other words, making transitioning to rated lighting difficult or impossible, can be formed after a predetermined amount of accumulated lamp lighting time has elapsed.

[0009] The shielding film can be formed on an inner surface portion facing a region of relatively high electric field strength along at least one of the lamp axial direction and the lamp circumferential direction. For example, the shielding film is formed on an inner surface portion facing a region of relatively high electric field strength along the lamp axial direction.

[0010] For example, the foil electrode may be configured so that its edge along the lamp axis is spaced from the inner surface of the dielectric between both ends of the foil electrode, and the auxiliary discharge space may be formed along the lamp axis across the length of the foil electrode.

[0011] The excimer lamp can be configured with an extension portion in which the dielectric extends from the end of the discharge vessel, and in the extension portion, a portion of the foil electrode can be partially sealed with the dielectric to form an auxiliary discharge space.

[0012] In another aspect of the present invention, an excimer lamp includes a dielectric covering foil electrodes arranged along the lamp axis and a discharge vessel welded to the dielectric to form a main discharge space, and a shielding film is formed on at least a portion of the inner surface of the dielectric exposed to the auxiliary discharge space, the shielding film suppressing transmission of electromagnetic waves due to discharge in an auxiliary discharge space formed inside the dielectric by partially sealing the foil electrodes to the dielectric. For example, the shielding film can be formed on an inner surface portion facing an area of ​​relatively high electric field strength along at least one of the lamp axial direction and the lamp circumferential direction.

[0013] Another aspect of the present invention is a method for manufacturing an excimer lamp, which includes the steps of inserting a foil-shaped inner electrode into a glass tube that will become the inner tube; reducing the pressure inside the inner tube and sealing it, or filling the inner tube with a rare gas at or below atmospheric pressure; heating and reducing the diameter of the inner tube to partially seal it with the inner electrode so that an auxiliary discharge space is formed in at least a portion of the inner tube along the tube axis direction; and inserting the inner tube into an outer tube that will become the discharge tube and fusing the outer tube to the expanded diameter portion of the inner tube, wherein in the rare gas filling step, the rare gas is filled at a predetermined pressure so that a shielding film that suppresses rated lighting due to discharge in the main discharge space is formed when the accumulated lamp lighting time exceeds a predetermined time.

[0014] Another aspect of the present invention is an excimer lamp comprising a dielectric covering an inner electrode arranged along the lamp axis, and a discharge vessel welded to the dielectric to form a main discharge space, wherein the inner electrode is partially sealed to the dielectric so that an auxiliary discharge space is formed inside the dielectric, and a shielding film that suppresses the transmission of electromagnetic waves is formed on at least a portion of the inner surface of the dielectric exposed to the auxiliary discharge space by discharge in the auxiliary discharge space, and at least one of the pressure of the gas sealed in the discharge vessel, the shape of the inner electrode, and the volume of the auxiliary discharge space is adjusted so that the shielding film that suppresses rated lighting due to discharge in the main discharge space is formed when the accumulated lamp lighting time exceeds a predetermined time. [Effects of the Invention]

[0015] According to the present invention, it is possible to provide an excimer lamp that can be made unlightable at the end of its lamp life before the discharge tube becomes brittle. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a schematic cross-sectional view of an excimer lamp according to a first embodiment, viewed from the side. [Figure 2] 1 is a schematic cross-sectional view of an excimer lamp according to a first embodiment, viewed from the axial direction. [Figure 3] FIG. 10 is a schematic cross-sectional view of the excimer lamp of the second embodiment as viewed from the side. [Figure 4] 10 is a schematic cross-sectional view of an excimer lamp according to a second embodiment, as viewed from the axial direction. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0018] Fig. 1 is a schematic cross-sectional view of the excimer lamp of the first embodiment as seen from the side. Fig. 2 is a schematic cross-sectional view of the excimer lamp of the first embodiment as seen from the axial side. Fig. 2 corresponds to a cross-sectional view taken along line BB in Fig. 1. The cross-sectional view in Fig. 1 corresponds to a cross-sectional view taken along a line passing through the central axis of the lamp in Fig. 2.

[0019] The excimer lamp 10 includes a discharge vessel 10T formed by an outer tube 20 made of a dielectric material such as quartz glass and having a substantially cylindrical cross section, and an inner tube 50. A foil electrode (hereinafter referred to as the inner electrode) 30 extending in a strip shape with a width along the tube radial direction (hereinafter also referred to as the lamp radial direction) is covered by a columnar dielectric (hereinafter referred to as the inner tube) 50 along the tube axis (hereinafter also referred to as the lamp axis) C. In this example, the inner tube 50 is formed to have a substantially circular cross section. The inner electrode 30 may be embedded in the inner tube 50.

[0020] One end 20T2 of the outer tube 20 is heat-welded integrally to the expanded diameter portion 51 of the inner tube 50, thereby forming an annular discharge space (hereinafter referred to as the main discharge space) S1. The inner electrode 30 is arranged coaxially with the outer tube 20 so that its center positions in the width and thickness directions are aligned with the lamp axis C. The inner electrode 30 is also arranged symmetrically with respect to the tube axis C.

[0021] The width of the inner electrode 30 is smaller at its edges than at its center, and the inner electrode 30 has a sharp cross-sectional shape, with edges 30T3 and 30T4 (see FIG. 2) having a knife-edge shape. The inner electrode 30 is made of molybdenum.

[0022] The main discharge space S1 is filled with a discharge gas such as a rare gas, such as xenon gas, or a mixture of a rare gas and a halogen gas. The pressure of the discharge gas is set to, for example, 5 kPa to 150 kPa. The inner electrode 30 is not exposed to the main discharge space S1.

[0023] In the discharge vessel 10T, protruding protrusions (hereinafter referred to as small diameter portions) 22, 52 are provided at both ends of a constant inner diameter portion (hereinafter referred to as a cylindrical portion) 20T0 that surrounds the main discharge space S1. The small diameter portion 52 is a small outer diameter portion that is not covered by the outer tube 20 and extends part of the rear end of the inner tube 50 along the lamp axis C beyond the end 21 of the outer tube 20, and a power supply line 70 passes through the interior.

[0024] The small diameter portion 22 is formed during the lamp manufacturing process and protrudes from the discharge vessel 10T (outer tube 20) toward the lamp tip along the lamp axis C. The small diameter portion 22 can be integrally formed by heating and deforming the tip side of the outer tube 20 to reduce its diameter, and welding a tip tube with a smaller diameter than the outer tube 20.

[0025] The tip portion of the end 50T1 of the inner pipe 50 is located in the spatial region of the small diameter portion 22, and the end 50T1 of the inner pipe 50 contacts the small diameter portion 22. This allows the inner pipe 50 to be stably held coaxially within the outer pipe 20. The outer surface of the end 50T1 of the inner pipe 50 has a tapered convex curved shape, and the inner surface of the small diameter portion 22 has a tapered concave curved shape. Note that the end 50T1 of the inner pipe 50 may not contact the small diameter portion 22.

[0026] An electrode (hereinafter referred to as the outer electrode) 40 is disposed on the outer surface of the outer tube 20. The outer electrode 40 is configured such that a linear electrode portion made of a conductive metal is wound along the outer surface of the outer tube 20, is wound in a spiral shape along the tube axis C, and is disposed at predetermined intervals.

[0027] The range L along the lamp axis in which the outer electrode 40 is disposed (axial arrangement range) is determined by a cylindrical portion 20T0, which is a constant inner diameter portion between the tapered ends 20T1 and 20T2 of the outer tube 20. The axial length of the inner electrode 30 corresponds to the axial arrangement range L of the outer electrode 40. A power supply line 70 connected to one end 30T2 of the inner electrode 30 is connected to an externally installed power supply unit (not shown), and power is supplied to the excimer lamp 10 via the power supply line 70.

[0028] Excimer light is emitted from the discharge space S1 by applying a high frequency (for example, in the range of several kHz to several tens of MHz) and a high voltage (for example, in the range of several kV to several tens of kV) to the inner electrode 30 and the outer electrode 40. That is, ultraviolet light (for example, wavelength 172 nm) is emitted to the outside of the discharge vessel 10T. The excimer lamp 10 can be applied to an ozone generator that performs sterilization, deodorization, etc. by generating ozone, and can also be applied to an ultraviolet irradiation device that directly irradiates an object with ultraviolet light.

[0029] A discharge space S2 for assisting in starting lighting (hereinafter referred to as auxiliary discharge space) is formed between the inner electrode 30 and the inner tube 50. Specifically, both axial ends 30T1, 30T2 of the inner electrode 30 are welded to the inner tube 50 over their entire circumference, and both axial ends 30T1, 30T2 of the inner electrode 30 are embedded in the inner tube 50, while between both ends 30T1, 30T2 of the inner electrode 30 (intermediate portion), the entire circumferential periphery of the inner electrode 30 is exposed, and the auxiliary discharge space S2 is formed so as to surround the inner electrode 30 (see FIG. 2 ).

[0030] The auxiliary discharge space S2 is in a reduced pressure state below atmospheric pressure. However, it is also possible to fill the auxiliary discharge space S2 with a rare gas (below atmospheric pressure) that lowers the voltage at the start of lighting. Furthermore, the range M of the auxiliary discharge space S2 along the lamp axis C (auxiliary discharge space range) is set to be shorter than the axial arrangement range L of the outer electrode 40.

[0031] As described above, the edges 30T3 and 30T4 of the inner electrode 30 are knife-edge shaped, and the distance T1 between the side surface of the inner electrode 30 and the inner surface 50S of the inner tube 50 is longer than the distance T2 between the edges 30T3 and 30T4 of the inner electrode 30 and the inner surface 50S of the inner tube 50. Therefore, electric field concentration occurs near the edges 30T3 and 30T4 of the inner electrode 30, and the electric field strength distribution in the main discharge space S1 and the auxiliary discharge space S2 is not uniform in the circumferential direction. On the other hand, the cross-sectional shape of the inner electrode 30 and the cross-sectional shapes in the lamp radial direction of the main discharge space S1 and the auxiliary discharge space S2 are approximately uniform along the lamp axis C, and the electric field strength distribution is not biased along the lamp axis C.

[0032] When a high-frequency high voltage is applied between the inner electrode 30 and the outer electrode 40, the auxiliary discharge space S2 is in a reduced-pressure state, and therefore a discharge occurs first due to electric field concentration in the auxiliary discharge space S2, with a lighting start voltage lower than that in the main discharge space S1. Then, part of the electromagnetic waves (here, light including ultraviolet rays) emitted from the auxiliary discharge space S2 in the lamp radial direction is irradiated through the inner tube 50 into the main discharge space S1.

[0033] In addition, a portion of the light emitted in the direction of the lamp axis from the discharge generated in the auxiliary discharge space S2 is transmitted toward its ends 50T1 and 50T2 due to the fiber effect (an effect based on the same principle as optical fibers used in communication circuits) caused by repeated reflection within the tube wall of the inner tube 50 (at the boundary surface of the tube wall).

[0034] As described above, part of the end 50T1 of the inner tube 50 enters into and contacts the small diameter portion 22, and the expanded diameter portion 51 is formed on the end 50T2 side of the inner tube 50. Therefore, the ultraviolet light guided to the ends 50T1, 50T2 passes through the end 50T1 and expanded diameter portion 51 of the inner tube 50 and is irradiated into the main discharge space S1 from both end portions 20T1, 20T2 of the outer tube 20.

[0035] Due to the ultraviolet light emitted from the auxiliary discharge space S2 toward the main discharge space S1 and the electric field concentration formed in the main discharge space S1, a discharge occurs in the main discharge space S1, and the excimer lamp 10 transitions to rated lighting. Every time the power is turned on (voltage is applied) to the excimer lamp 10, the lamp is lit with high lighting startability using the auxiliary discharge.

[0036] As described above, the auxiliary discharge space S2 is a space formed between the inner surface 50S of the inner tube 50 and the inner electrode 30, and the inner electrode 30 is exposed to the auxiliary discharge space S2 between its end portions 30T1 and 30T2.

[0037] Therefore, while the lamp is lit, i.e., while an electric field is generated by voltage application, molybdenum evaporates from the inner electrode 30 due to the sputtering phenomenon and partially adheres to the inner surface 50S of the inner tube 50. As the molybdenum evaporates from the inner electrode 30, impurity gases are released into the auxiliary discharge space S2. This sputtering phenomenon continues while the lamp is lit, and the inner electrode 30 wears and deforms, reducing the electric field concentration. In other words, the electric field intensity distribution changes to become more uniform.

[0038] Molybdenum adheres to the inner surface 50S of the inner tube 50 in accordance with the accumulated lamp lighting time, forming a thin film F on the inner surface 50S of the inner tube 50. The thin film F functions to reduce the transmittance of the inner tube (quartz glass in this case) 50 to electromagnetic waves, suppressing the transmission of light including ultraviolet rays irradiated from the auxiliary discharge space S2 toward the main discharge space S1, and suppressing the transmission of electromagnetic waves that form a spatial region with a relatively high electric field intensity in the main discharge space S1.

[0039] The sputtering phenomenon is likely to occur in spatial regions where the electric field strength is relatively high near the edges 30T3 and 30T4 of the inner electrode 30, and as the inner electrode 30 continues to wear out while the lamp is lit (flashing), it also begins to occur on the side surfaces of the inner electrode 30. Therefore, the thin film (hereinafter referred to as the shielding film) F formed on the inner surface of the inner tube 50 exposed to the auxiliary discharge space S2 is formed predominantly in the inner surface portion facing the edges 30T3 and 30T4 of the inner electrode 30, and spreads to the entire inner surface as the accumulated lamp lighting time becomes longer. However, Fig. 2 shows the formation range of the shielding film F schematically, and is not limited to such range and thickness.

[0040] As the accumulated lamp lighting time of the excimer lamp 10 increases, the shielding film F is formed as a film that further suppresses irradiation of light, including ultraviolet light, toward the main discharge space S1 and further reduces the transmittance of electromagnetic waves incident on the inner tube 50. As a result, lighting startability deteriorates and the time until the lamp reaches rated lighting increases.

[0041] Then, when the accumulated lamp lighting time exceeds a predetermined time, i.e., when the lamp reaches the end of its life, the shielding film F causes the ultraviolet radiation and electric field strength toward the main discharge space S1 to become insufficient to transition to rated lighting, and lamp lighting start-up is suppressed. At the same time, the sputtering phenomenon causes the inner electrode to deform, preventing the formation of areas with relatively high electric field strength in the auxiliary discharge space and main discharge space. Furthermore, the sputtering phenomenon causes impure gas to be released from the inner electrode, preventing discharge from occurring in the auxiliary discharge space. These factors suppress lamp lighting start-up. In other words, the lamp cannot be re-ignited. Since the lamp cannot be re-ignited, it is determined that the excimer lamp 10 has reached the end of its lamp life, and the lamp is replaced.

[0042] As described above, according to this embodiment, in the excimer lamp 10 with a double-tube structure, an auxiliary discharge space S2 is formed between the inner surface of the inner tube 50 and the inner electrode 30, and an auxiliary discharge that emits light containing ultraviolet light that improves lighting startability occurs in the auxiliary discharge space S2. At the same time, as the inner electrode 30 wears away, a shielding film F is formed due to the sputtering phenomenon in accordance with the accumulated lamp lighting time. Then, at the end of the lamp's life, the lamp will no longer be able to light at its rated capacity.

[0043] The formation of the shielding film F makes it impossible for the lamp to light at its rated capacity, which causes deterioration of the discharge vessel 10T due to ultraviolet radiation, and even the application of a small force can cause breakage or cracks, making it possible to replace the lamp before the discharge vessel 10T becomes weak. Note that by adjusting the lighting control of the excimer lamp 10, it is possible to perform flashing lighting, in which a transient discharge state continues. In this case, the flashing state changes to an unlightable state, making it possible to replace the lamp before the discharge vessel 10T becomes weak.

[0044] Since the electric field strength distribution is not uniform around the circumferential direction of the inner electrode 30, and the electric field strength is relatively low near the center in the width direction of the side portion of the inner electrode 30 and relatively high near the edges 30T3 and 30T4, a shielding film F is formed on a part of the inner surface of the inner tube 50. Therefore, as the accumulated lamp lighting time becomes longer, the area on which the shielding film F is formed increases, and while maintaining lighting startability that allows the lamp to transition to stable rated lighting until the end of its life, a shielding film F is formed that further suppresses irradiation of electromagnetic waves (light including ultraviolet rays) in accordance with the accumulated lamp lighting time.

[0045] In particular, as the lamp approaches the end of its life, its lighting startability deteriorates, lengthening (delaying) the time from voltage application to rated lighting due to discharge in the main discharge space S1. Therefore, the control unit of the ozone generator detects the end of the lamp's life by checking the time until visible light begins to be emitted from the excimer lamp 10 along with ultraviolet light, thereby rendering the lamp unable to light. Furthermore, the user can detect the end of the lamp's life by estimating the accumulated lamp lighting time from appearance by checking the reduction in the area and transmittance of the shielding film F formed on the inner surface of the inner tube 50.

[0046] The above-described excimer lamp 10 can be manufactured, for example, by the following manufacturing process.

[0047] A glass tube (inner tube) with a cylindrical cross section that serves as a covering for the foil electrode (inner electrode) is formed from a dielectric material that is transparent to the light emitted from the discharge formed in the auxiliary discharge space. After the inner tube is formed, a power supply wire is connected to the foil electrode by resistance welding or the like, and the foil electrode is inserted into the cylindrical glass tube with a bottom. After the foil electrode is inserted, the glass tube is reduced in pressure (vacuum) and sealed. At this time, a rare gas may be sealed in the glass tube at sub-atmospheric pressure.

[0048] The glass tube is heated while being rotated, and deformed so that it softens and shrinks (reduced in diameter). At this time, only the areas near both ends of the inner electrode along the tube axis are heated, and the area along the lamp axis that corresponds to the auxiliary discharge space is not heated or heated less, thereby suppressing (stopping) the reduction in diameter due to softening of the glass tube and forming the auxiliary discharge space.

[0049] In addition to forming an auxiliary discharge space, a flange-shaped (so-called abacus bead-shaped) enlarged diameter portion is formed at one end of the glass tube. Alternatively, the glass tube may be heated axially only at the portion of the glass tube facing the edge of the foil electrode to seal it in place, without rotating the glass tube. The end of the foil electrode along its length (tube axis direction) is sealed along its entire circumference, so that the end of the foil electrode is embedded in the glass tube and is not exposed to the auxiliary discharge space.

[0050] The outer tube is a quartz tube that is transparent to the wavelength of ultraviolet light emitted from the discharge formed in the main discharge space, and one end of the tube is narrowed and an open introduction tube (tip tube) is provided. On the other hand, the outer tube is formed with an open sealing portion that is connected to the expanded diameter portion of the inner tube.

[0051] The inner tube is then inserted into the outer tube, and the inner tube and outer tube are heat-fused together at the sealing portion to form a discharge tube. A vacuum is then drawn through the inlet tube to remove impurities, and a discharge gas is sealed inside the arc tube. The inlet tube is then heat-fused to form an airtight seal. After sealing, an outer electrode is attached to the outer surface of the outer tube.

[0052] To maintain stable lighting startability until the end of its life while preventing transition to rated lighting before the discharge vessel 10T becomes brittle, it is preferable to form areas with relatively high and relatively low electric field strength. The shape of the inner electrode 30 is not limited to the shape of the edges 30T3 and 30T4 (knife-edge shape), and any shape may be used in which the electric field strength distribution is not uniform in the circumferential direction. For example, in the case of a rod-shaped electrode, it is sufficient to process a portion of the shape so that electric field concentration occurs. Furthermore, the inner electrode 30 and the inner tube 50 may be partially sealed together so that areas with relatively high and low electric field strength are generated along the lamp axis.

[0053] On the other hand, by adjusting the volume of the auxiliary discharge space, it is also possible to form a shielding film F that disables the transition to rated lighting before the discharge vessel 10T becomes weak. Furthermore, it is also possible to form a shielding film F that disables the transition to rated lighting before the discharge vessel 10T becomes weak by adjusting the pressure of the gas sealed in the main discharge space S1.

[0054] In this embodiment, the auxiliary discharge space S2 is formed over a section corresponding to the length of the inner electrode 30, but it may also be formed only in a part of the discharge vessel 10T along the lamp axis, for example, in the central part, or only near the end of the inner electrode 30.

[0055] Next, an excimer lamp according to a second embodiment will be described with reference to Figures 3 and 4. In the second embodiment, an auxiliary discharge space is formed in an extension of the inner tube beyond the discharge vessel.

[0056] Fig. 3 is a schematic cross-sectional view of the excimer lamp of this embodiment as seen from the side. Fig. 4 is a schematic cross-sectional view of the excimer lamp of this embodiment as seen from the axial direction. Fig. 3 corresponds to the cross-sectional view taken along line BB in Fig. 1. The cross-sectional view in Fig. 4 corresponds to the cross-sectional view taken along a line passing through the central axis of the lamp in Fig. 2.

[0057] The excimer lamp 100 has a portion (hereinafter referred to as an extension portion) 152 that is not covered by the outer tube 120 and extends beyond the end 120T2 of the outer tube 120 along the lamp axis C, and a power supply line 170 passes through the inside of this end 150T2. However, the extension portion 152 may also be formed by welding a separate member that is different from the inner tube 150. The small diameter portion 122, which is formed during the lamp manufacturing process, protrudes from the discharge vessel 100T (outer tube 120) toward the lamp tip along the lamp axis C.

[0058] An auxiliary discharge space S2 is formed in the extension 152. As shown in Fig. 3, a portion of the extension 152 of the inner tube 150 along the lamp axis C is not partially welded (sealed) around the entire circumferential direction of the inner electrode 130. On the other hand, both axial end portions 130T1 and 130T2 of the inner electrode 130 are sealed to the inner tube 150 around the entire circumference. This forms the auxiliary discharge space S2.

[0059] Here, the range M of the auxiliary discharge space S2 along the lamp axis C (auxiliary discharge space range) is determined to be a section outside the axial arrangement range of the inner electrode 130 corresponding to the axial arrangement range L of the outer electrode 140. That is, in the axial arrangement range L of the outer electrode 140, in the ranges of both end portions 130T1, 130T2 of the inner electrode 130, the inner electrode 130 is sealed to the inner tube 150 around the entire circumferential direction. In contrast, in the middle part of the extending portion 152 of the inner tube 150, the entire outer peripheral surface of the inner electrode 130 is exposed, and the auxiliary discharge space S2 is formed to surround it.

[0060] As in the first embodiment, the auxiliary discharge space S2 is in a reduced pressure state lower than atmospheric pressure, or a rare gas (lower than atmospheric pressure) that lowers the voltage at the start of lighting is sealed in the auxiliary discharge space S2. When a high-frequency high voltage is applied between the inner electrode 130 and the outer electrode 140, a discharge occurs first in the auxiliary discharge space S2 due to the lighting start voltage that is lower than that in the main discharge space S1. Then, part of the ultraviolet light emitted from the auxiliary discharge space S2 in the lamp axial direction is irradiated onto the main discharge space S1 through the inner tube 150.

[0061] A portion of the light emitted in the lamp axial direction from the discharge generated in the auxiliary discharge space S2 is repeatedly reflected within the tube wall (boundary surface of the tube wall) of the inner tube 150, a so-called fiber effect, and is transmitted toward the end 150T1 side of the inner tube 150. A portion of the ultraviolet light transmitted by the fiber effect passes through the expanded diameter portion 151 of the inner tube 150 and is irradiated from the end 120T2 side of the outer tube 120 into the main discharge space S1.

[0062] Furthermore, part of the light emitted in the lamp axial direction is irradiated into the main discharge space S1 from the end 120T1 side of the outer tube 120 through the end 150T1 of the inner tube 150, because the end 150T1 of the inner tube 150 partially enters and contacts the small diameter portion 22. The ultraviolet light transmitted by this fiber effect is irradiated into the main discharge space S1, causing a discharge in the main discharge space S1. In this way, forming the auxiliary discharge space S2 in part of the extension 152 of the inner tube 150 improves lighting start-up performance.

[0063] The spatial area of ​​the auxiliary discharge space S2 in the extension 152 and the formation section M along the lamp axis C can be adjusted as needed. For example, by welding only the two edge portions 130T3, 130T4 of the inner electrode 130 to the inner tube 150 so that they are not exposed, two discharge spatial areas spaced apart by the foil-like inner electrode 130 can be formed as the auxiliary discharge space S2.

[0064] Furthermore, a dielectric may be coated (covered) on at least a portion of the surface of the inner electrode within the defined auxiliary discharge space range M, so that both edge portions 130T3 and 130T4 of the inner electrode 130 are not exposed to the auxiliary discharge space S2. These configurations are also applicable to the first embodiment.

[0065] Such an excimer lamp 100 can be manufactured, for example, by the following manufacturing method.

[0066] A cylindrical glass tube (inner tube) is formed from a dielectric material that is transparent to the light emitted from the discharge formed in the auxiliary discharge space. After the inner tube is formed, a power supply wire is connected to the foil electrode by resistance welding or the like, and the foil electrode is inserted into a cylindrical glass tube with a bottom.

[0067] After inserting the foil electrode that will become the inner electrode into the glass tube that will become the inner tube, the glass tube is reduced in pressure (vacuum) and sealed. At this time, a rare gas may be sealed inside the glass tube at sub-atmospheric pressure. Then, while rotating the glass tube, it is heated to soften and shrink (reduced in diameter) so that an auxiliary discharge space is partially formed at the end of the glass tube, and the glass tube and the inner electrode are partially fused together.

[0068] In this case, by bringing only the edge portion along the width direction (tube diameter direction) of the foil electrode into close contact with the inner surface of the glass tube, the edge portion of the foil electrode is not exposed, and a space where the glass tube and the foil electrode are not in contact can be formed as an auxiliary discharge space.

[0069] Furthermore, one end of the glass tube that will become the inner tube is heated to form a flange-shaped (so-called abacus bead-shaped) enlarged diameter portion. Alternatively, the glass tube may be heated along the axial direction only at the portion of the glass tube that faces the inner circumferential surface and the edge of the foil electrode to seal them together, without rotating the glass tube. The end of the foil electrode along its length (tube axis direction) is sealed along the entire circumference, so that the end of the foil electrode is embedded in the glass tube and is not exposed to the auxiliary discharge space.

[0070] Regarding the outer tube, one end of a quartz tube that is transparent to the wavelengths of ultraviolet light emitted from the discharge formed in the main discharge space is reduced in diameter and an open introduction tube (tip tube) is provided, while the outer tube is formed with an open sealing portion that connects to the expanded diameter portion of the inner tube.

[0071] The inner tube is then inserted into the outer tube and arranged coaxially, and the discharge tube and the expanded portion of the inner tube are heat-fused together so that a portion of the inner tube extends from the discharge tube and the auxiliary discharge space is located outside the discharge tube, thereby forming a discharge vessel. A vacuum is then drawn through the feed tube to remove impurities, and a discharge gas is sealed inside the discharge vessel, which is then hermetically sealed by heat-melting the feed tube. An outer electrode is then disposed on the outer surface of the outer tube.

[0072] In this embodiment, the inner electrode 30 extends into the discharge vessel 10T and into the extension 152, but different inner electrodes may be disposed in the discharge vessel 10T and the extension 152. For example, an internal power supply line may be disposed in the expanded diameter portion to connect the two electrodes.

[0073] The inner electrode may be made of a material on which a shielding film is formed by sputtering, and the outer electrodes may be embedded in the inner wall of the discharge tube so as to face each other, or one may be embedded and the other may be disposed on the outer surface of the discharge tube. [Example]

[0074] An excimer lamp as an example will be described below. The excimer lamp of the example corresponds to the excimer lamp of the first embodiment, and xenon gas is sealed in the main discharge space at 40 kPa. The auxiliary discharge space is 26 mm long, has an inner diameter of 2 mm, and an outer diameter of 4 mm, and is sealed with argon gas at 5 kPa.

[0075] The excimer lamp was turned on, and the cumulative lighting time and the presence or absence of a shielding film were checked. As the cumulative lighting time increased, the formation of a shielding film was confirmed. When the cumulative lighting time exceeded 2000 hours, a lighting delay of approximately 5 seconds occurred. [Explanation of symbols]

[0076] 10 Excimer Lamp 20 Outer tube 30 inner electrode 40 outer electrode 50 Inner tube (dielectric)

Claims

1. a dielectric covering the foil electrodes arranged along the lamp axis; a discharge vessel that is welded to the dielectric to form a main discharge space, the foil electrodes are partially sealed to the dielectric at both ends so as to form an auxiliary discharge space inside the dielectric, the entire space being surrounded by the main discharge space; An excimer lamp characterized in that a shielding film for suppressing transmission of electromagnetic waves is formed on at least a part of the inner surface of the dielectric exposed to the auxiliary discharge space by discharge in the auxiliary discharge space.

2. 2. The excimer lamp according to claim 1, wherein the shielding film that suppresses rated lighting due to discharge in the main discharge space is formed when the accumulated lamp lighting time exceeds a predetermined time.

3. 3. The excimer lamp according to claim 1, wherein the shielding film is formed on an inner surface portion facing a region of relatively high electric field strength along at least one of the lamp axial direction and the lamp circumferential direction.

4. 4. The excimer lamp according to claim 1, wherein the shielding film is formed on an inner surface portion facing a region of relatively high electric field strength along the lamp axis direction.

5. 5. The excimer lamp according to claim 1, wherein an edge of said foil electrode along the lamp axis is spaced apart from the inner surface of said dielectric between both ends of said foil electrode.

6. 6. The excimer lamp according to claim 1, wherein the auxiliary discharge space is formed along the lamp axis direction, spanning between both ends of the foil electrode.

7. the dielectric has an extension extending from an end of the discharge vessel, 6. The excimer lamp according to claim 1, wherein a part of the foil electrode is partially sealed with the dielectric in the extension portion to form the auxiliary discharge space.

8. An excimer lamp comprising a dielectric covering foil electrodes arranged along the lamp axis, and a discharge vessel welded to the dielectric to form a main discharge space, A method for operating an excimer lamp, characterized in that a shielding film that suppresses the transmission of electromagnetic waves is formed on at least a portion of the inner surface of the dielectric that is exposed to the auxiliary discharge space by discharge in an auxiliary discharge space formed inside the dielectric by partially sealing the foil electrode with the dielectric.

9. 9. The method for operating an excimer lamp according to claim 8, wherein the shielding film is formed on an inner surface portion facing a region of relatively high electric field strength along at least one of the lamp axial direction and the lamp circumferential direction.

10. a step of inserting a foil-shaped inner electrode into a glass tube that will become an inner tube; a step of reducing the pressure inside the inner tube and sealing it, or sealing a rare gas in the inner tube at atmospheric pressure or below; a step of heating the inner tube and reducing its diameter to partially seal the inner electrode so that an auxiliary discharge space is formed in at least a portion of the inner tube along the tube axis direction; a step of inserting the inner tube into an outer tube that serves as a discharge tube, and welding the outer tube to the expanded diameter portion of the inner tube, A method for manufacturing an excimer lamp, characterized in that in the rare gas sealing step, a rare gas is sealed in at a predetermined pressure so that a shielding film that suppresses rated lighting due to discharge in the main discharge space is formed when the accumulated lamp lighting time exceeds a predetermined time.

11. a dielectric covering an inner electrode disposed along the lamp axis; a discharge vessel that is welded to the dielectric to form a main discharge space, the inner electrode is partially sealed with the dielectric so that an auxiliary discharge space is formed inside the dielectric; an excimer lamp in which a shielding film for suppressing transmission of electromagnetic waves is formed on at least a part of an inner surface of the dielectric that is exposed to the auxiliary discharge space by discharge in the auxiliary discharge space, an excimer lamp characterized in that at least one of the pressure of the gas sealed in the discharge vessel, the shape of the inner electrode, and the volume of the auxiliary discharge space is adjusted so that a shielding film that suppresses rated lighting due to discharge in the main discharge space is formed when the accumulated lamp lighting time exceeds a predetermined time.

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