JP5266972B2 - Excimer lamp - Google Patents

Abstract

Provided is an excimer lamp having a discharge container with a tube of rectangular section shape to prevent the edges from becoming the damage starting points and causing breakage of the discharge container. In the discharge space (S) of the discharge container (11), the excimer lamp (10) causing excimer discharge is parallel to the section taken from the terminals (14a, 14b), and the long edge sides (12a, 12b) of the discharge container (11) are corresponding to the edges (16a, 16b, 16c, 16d) of the long edge sides (12a, 12b) and the short edge sides (13a, 13b). The middle parts (121a, 121b) of the long edge sides (12a, 12b) are formed by inwardly bending toward the discharge space (S). A UV reflection film (20) is formed on the surface of the discharge space (S) exposed to the discharge container (11), and the thickness of the UV reflection film (20) at the edge is thicker than that at the central part.

Description

  The present invention excites a discharge gas through a discharge vessel made of silica glass, a pair of electrodes facing each other, and a silica glass forming the discharge vessel between the pair of electrodes. The present invention relates to an excimer lamp that generates excimer discharge.

  In recent years, an object to be processed made of metal, glass, or other material is irradiated with vacuum ultraviolet light having a wavelength of 200 nm or less to process the object to be processed by the action of the vacuum ultraviolet light and ozone generated thereby. Technology, for example, a cleaning processing technology for removing organic contaminants attached to the surface of the object to be processed and an oxide film forming processing technology for forming an oxide film on the surface of the object to be processed have been developed and put into practical use.

  In these apparatuses, as a light source for irradiating vacuum ultraviolet light, for example, an excimer lamp that forms excimer molecules by excimer discharge and uses light generated when the excimer molecules decay, for example, light having a wavelength of about 172 nm, is used. Are known. Many attempts have been made for such excimer lamps to efficiently emit higher-intensity ultraviolet rays.

  FIG. 5 is an explanatory perspective view showing a configuration of a conventional excimer lamp described in Japanese Patent Application Laid-Open No. 2004-127710. A conventional excimer lamp 60 includes a discharge vessel 61 that is rectangular in cross section and made of silica glass that transmits ultraviolet rays, and a pair of electrodes 65 and 66 are formed on the outer surface of the discharge vessel 61. The discharge vessel 61 is filled with xenon gas as a discharge gas. In addition, when excimer lamp 60 is supplied with lighting power to one of the electrodes 65, excimer molecules are formed, and so-called excimer discharge is generated in which vacuum ultraviolet light is emitted as the excimer molecules decay. Yes.

  Since vacuum ultraviolet light is extremely high energy light, if silica glass is continuously irradiated with this strong vacuum ultraviolet light for a long time, defects due to ultraviolet rays are generated in the silica glass, which causes ultraviolet distortion. In some cases, fine cracks and cracks occur. In particular, at the outermost surface facing the discharge space, the vacuum ultraviolet light generated in the discharge space is directly irradiated to the surface with most of light in the wavelength region with high energy on the short wavelength side, and the surface contracts. A strong UV distortion is formed. On the other hand, the vacuum ultraviolet light irradiated on the outer surface of the discharge vessel 61 is attenuated by the thickness of the glass forming the discharge vessel 61, and the amount of ultraviolet strain formed in the direction of shrinkage due to ultraviolet strain is as follows. Remarkably less than the surface. Due to the difference in the amount of ultraviolet distortion generated, tensile stress is applied to the outermost surface facing the discharge space, and the outer surface is deformed in the extending direction.

FIG. 6 is an explanatory cross-sectional view for explaining a modification of the discharge vessel 61 of the conventional excimer lamp.
The discharge vessel 61 is arranged such that long side surfaces 62a and 62b made of long plate glass face each other, and a tube having a rectangular cross section is formed by the short side surfaces 63a and 63b connecting the long side surface 62a and the long side surface 62b. Is formed. The arrow indicates the direction of the stress acting inside the discharge vessel.

On the outermost surface facing the discharge space of the long side surfaces 62a and 62b and the short side surfaces 63a and 63b, a lot of light in the short wavelength region with high energy is absorbed in the vacuum ultraviolet light, so that ultraviolet distortion is formed. The force works in the direction of shrinking as shown by the arrow. On the other hand, a force acts on the outer surface of the discharge vessel 61 in a direction extending as indicated by an arrow. In the discharge vessel 61 having a rectangular cross section, due to the shape characteristics, the edge portions 64a, 64b, 64c, 64d connecting the long side surfaces 62a, 62b and the short side surfaces 63a, 63b are arranged in the long side surfaces 62a, 62b direction. The stress that expands and contracts and the stress that expands and contracts in the direction of the short side surfaces 63a and 63b work, and the stress concentrates on the edge portions 64a, 64b, 64c, and 64d. Therefore, the distortion accumulated due to the stress concentration causes the edge portions 64a, 64b, 64c, and 64d to be the starting points of the damage, causing a problem that the discharge vessel 61 is destroyed.
JP 2004-127710 A

  The present invention has been made to solve the above problem, and in an excimer lamp equipped with a tube-shaped discharge vessel having a rectangular cross section, the discharge vessel is destroyed with the edge portion as a starting point of breakage. An object is to provide an excimer lamp that can be prevented.

The excimer lamp according to claim 1 of the present invention includes a discharge vessel having a rectangular cross section that is closed at both ends by end surfaces and surrounded by a long side surface facing each other and a short side surface connecting the long side surfaces, An excimer lamp in which a pair of electrodes are disposed on the long side surface or the short side surface of the discharge vessel facing each other, and an xenon gas is sealed inside the discharge vessel to generate excimer discharge in the discharge space. The long side surface is curved in a direction in which a central portion of the long side surface faces the inside of the discharge space with respect to an edge portion connecting the long side surface and the short side surface, On the inner surface of the vessel, an ultraviolet reflecting film having a central portion curved in a direction toward the inside of the discharge space is formed, and the thickness of the ultraviolet reflecting film formed on the edge portion of the discharge vessel is larger. It is thicker than the film thickness formed on other inner surfaces. The features.

  Further, in the excimer lamp according to claim 2 of the present invention, in addition to the above configuration, the short side surface has an edge portion connecting the long side surface and the short side surface to the short side surface. The center portion is curved in a direction toward the inside of the discharge space.

  Furthermore, the excimer lamp according to claim 3 of the present invention is characterized in that, in addition to the above configuration, the ultraviolet reflecting film includes silica particles and alumina particles.

  According to the excimer lamp of the first aspect of the present invention, the discharge vessel has a central portion of the long side surface on the inner side of the discharge space with respect to an edge portion connecting the long side surface and the short side surface. The film thickness of the ultraviolet reflecting film formed on the inner surface of the discharge vessel is curved in the direction toward which the film thickness formed on the edge portion is compared to the film thickness formed on the other portions. It ’s getting thicker. Therefore, the edge portion that is likely to be a starting point of breakage is sufficiently blocked by vacuum ultraviolet light by the thick ultraviolet reflecting film, and damage such as ultraviolet distortion generated at the edge portion can be reduced. There is an advantage that it is possible to prevent problems such as destruction of the battery.

  According to the excimer lamp according to claim 2 of the present invention, the central portion of the short side surface is curved in the direction toward the inside of the discharge space with respect to the edge portion connecting the long side surface and the short side surface. Yes. For this reason, even if the film thickness of the ultraviolet reflecting film formed on the inner surface of the central part of the short side surface is thin, the film thickness of the ultraviolet reflecting film can be increased on the inner surface near the edge part. That is, the strong vacuum ultraviolet light generated in the discharge space can be increased to such an extent that it can be selectively blocked at the edge portion. For this reason, damage such as ultraviolet distortion generated at the edge portion can be reduced. As a result, there is an advantage that problems such as destruction of the discharge vessel can be prevented.

  According to the excimer lamp according to claim 3 of the present invention, by including silica particles in the ultraviolet reflection film, it is possible to increase the adhesive force with the discharge vessel made of silica glass, and to the alumina film in the ultraviolet reflection film. By including particles, there is an advantage that the reflection characteristics of ultraviolet rays can be maintained for a long time. Furthermore, the alumina particles inhibit the silica particles adjacent to each other from being melt-bonded by the heat generated by the discharge, so that the boundary between the particles can be maintained, and the ultraviolet reflection characteristics can be maintained for a long time. .

FIG. 1 is an explanatory cross-sectional view showing an outline of the configuration of an example of an excimer lamp 10 according to the present invention, and FIG. 1- (a) is a cross-sectional view showing a cross section along the longitudinal direction of the discharge vessel 11. FIG. 1B is a cross-sectional view taken along line AA in FIG.
The excimer lamp 10 includes a discharge vessel 11 having a rectangular cross section and a long hollow shape in which both ends are hermetically sealed and a discharge space S is formed therein. Xenon gas is enclosed as a discharge gas. Here, the amount of the xenon gas filled is such that the pressure falls within a range of 10 to 60 kPa, for example.
The discharge vessel 11 is made of silica glass, for example, synthetic quartz glass, which transmits vacuum ultraviolet light well, and also functions as a dielectric.

The discharge vessel 11 is arranged such that long side surfaces 12a and 12b made of a long plate glass face each other, and a tube having a rectangular cross section by short side surfaces 13a and 13b connecting the long side surface 12a and the long side surface 12b. Is formed. Both ends in the longitudinal direction are closed by end surfaces 14a and 14b, and the inside of the discharge space S is an airtight space. For example, the discharge vessel 11 has a length in the longitudinal direction of 800 to 1600 mm and a discharge space S of 320 to 640 cm ³ .

  A pair of grid-like electrodes 15a and 15b are formed on the outer surfaces of the long side surfaces 12a and 12b in the discharge vessel 11 so as to extend in the long direction. One electrode 15a that functions as a high-voltage power supply electrode is disposed on the outer surface of the long side surface 12a, and the other electrode 15b that functions as a ground electrode is disposed on the outer surface of the long side surface 12b. As a result, the discharge vessel 11 functioning as a dielectric is interposed between the pair of electrodes 15a and 15b. Such electrodes 15a and 15b can be formed, for example, by applying an electrode material made of metal to the discharge vessel 11 or by printing.

  In this excimer lamp 10, when lighting power is supplied to one of the electrodes 15a, a discharge is generated between the electrodes 15a and 15b through the wall of the discharge vessel 11 functioning as a dielectric. An excimer discharge is generated in which vacuum ultraviolet light is emitted as the excimer molecules are formed and decayed.

The excimer lamp 10 is provided with an ultraviolet reflecting film 20 made of ultraviolet scattering particles on the surface exposed to the discharge space S of the discharge vessel 11 in order to efficiently use vacuum ultraviolet light generated by excimer discharge. .
The ultraviolet reflecting film 20 includes an inner surface region corresponding to one electrode 15a functioning as a high-voltage power supply electrode on the long side surface 12a of the discharge vessel 11, and inner surface regions of the short side surfaces 13a and 13b continuous with this region. Is formed over. Further, the ultraviolet reflecting film 20 is also formed in the inner surface regions of the end faces 14a and 14b. On the other hand, the light emitting portion 17 is configured by the ultraviolet reflecting film 20 not being formed in the inner surface region corresponding to the other electrode 15b functioning as the ground electrode on the long side surface 12b of the discharge vessel 11. In addition, reflection efficiency can be improved by forming the ultraviolet-ray reflective film 20 also in the inner surface area | region of the edge part in which the electrode 15b of the long side surface 12b is not formed.

FIG. 2 is a schematic cross-sectional view cut in parallel to the end faces 14a and 14b (a plane orthogonal to the lamp tube axis) in order to explain the details of the excimer lamp 10 of the present invention. In particular, this figure is a conceptual diagram that emphasizes the warpage state of each glass surface and the difference in thickness of the ultraviolet reflecting film.
One end of the short side surface 13a or the short side surface 13b is joined to both ends of the long side surface 12a, the edge portion 16a joining the long side surface 12a and the short side surface 13a, and the long side surface 12a and the short side surface 13b. An edge portion 16b that joins is formed. Similarly, one end of the short side surface 13b or the short side surface 13a is joined at both ends of the long side surface 12b, the edge portion 16c joining the long side surface 12b and the short side surface 13b, and the long side surface 12b and the short side surface 12b. An edge portion 16d that joins the side surfaces 13a is formed.

  The central portion 121a of the long side surface 12a is positioned inward of the discharge space S with respect to the edge portions 16a and 16b existing on the long side surface 12a and extending from the central portion 121a. The side surface 12a itself is curved in a direction toward the inside of the discharge space S. A distance D between the central portion 121a of the long side surface 12a and the edge portion 16b is about 0.2 mm. The same applies to the long side surface 12b arranged to face the long side surface 12a.

  In addition, the short side surface 13a also has a central portion 19a positioned inward of the discharge space S with respect to the edge portions 16a and 16d existing on the extension of the central portion 19a on the short side surface 13a. The side surface 13a itself is curved in a direction toward the inside of the discharge space S. The same applies to the short side surface 13b arranged to face the short side surface 13a.

  When viewed as a whole of the discharge vessel 11, in the cross section cut parallel to the end faces 14a and 14b, the edge portions 16a, 16b, 16c and 16d are also in the direction in which the long side face 12a and the long side face 12b face each other. And the short side surface 13b are also bulging outwardly from the discharge space S. In other words, in the discharge vessel 11, the central portions 121a and 121b of the long side surfaces 12a and 12b and the central portions 19a and 19b of the short side surfaces 13a and 13b slightly protrude toward the inside of the discharge space S. It has a curved shape. Further, the ultraviolet reflecting film 20 formed on the inner surface of the discharge vessel 11 is formed to have a thicker film thickness at the edge portions 16a, 16b, 16c, and 16d than at the central portions 121a and 121b or the central portions 19a and 19b. Has been.

  The ultraviolet reflecting film 20 formed in the inner surface region of the long side surface 12a is intended to reflect the vacuum ultraviolet light generated in the discharge space S, and thus has a sufficiently large film thickness, for example, the central portion 121a. In this case, it is preferable to form approximately 30 μm. By sufficiently taking the film thickness of the ultraviolet reflecting film 20, not only the light incident on the ultraviolet reflecting film 20 is not transmitted to the discharge vessel 11, but also the vacuum ultraviolet light is reflected and returned to the discharge space S again. .

  On the other hand, the ultraviolet reflecting film 20 formed on the inner surface region of the short side surface 13a is intended to protect the discharge vessel 11 exposed to vacuum ultraviolet light, and therefore does not need a function of reflecting vacuum ultraviolet light. It is sufficient if it is formed with a minimum thickness that hardly transmits vacuum ultraviolet light. For example, if the inner surface region of the central portion 19a is formed to have a thickness of 2 to 3 μm, the ultraviolet reflecting film 20 can block vacuum ultraviolet light by about 90%.

  Further, as the ultraviolet scattering particles constituting the ultraviolet reflecting film 20, for example, silica particles made of silica glass in fine powder form are used. The silica particles preferably have a particle size in the range of 0.01 to 20 μm, for example, and the center particle size (peak value of the number average particle size) is preferably 0.1 to 10 μm, for example. Preferably it is 0.3-3 micrometers. Moreover, it is preferable that the distribution of the particle size of the silica particles contained in the ultraviolet reflecting film 20 is not wide, and the silica particles selected so that the particle size becomes the value of the center particle size become more than half. It is preferable to use it.

  The silica particles cause the ultraviolet reflective film 20 to adhere to the discharge vessel 11 by being partially melted or the like. In general, those having the same or similar linear expansion coefficient have the property of being easily bonded. Since the silica particles have the same linear expansion coefficient value as the discharge vessel 11 made of silica glass, the silica particles have a function of increasing the adhesive force with the discharge vessel 11.

  However, the silica particles are melted by the heat of the plasma generated in the excimer lamp 10 and the grain boundary disappears, so that the vacuum ultraviolet light cannot be diffusely reflected and the reflectance may be lowered. By including not only silica particles but also alumina particles as ultraviolet scattering particles, alumina particles having a melting point higher than that of silica particles do not melt even when exposed to heat from plasma. The grain boundary is maintained by preventing the alumina particles from being bonded to each other.

  The alumina particles preferably have a particle diameter in the range of 0.1 to 10 μm, for example, and the center particle diameter (peak value of the number average particle diameter) is preferably 0.1 to 3 μm, for example. Preferably it is 0.3-1 micrometer. Further, it is preferable that the particle size distribution of the alumina particles contained in the ultraviolet reflecting film 20 is not widened widely, and the alumina particles selected so that the particle size of the alumina particles becomes the value of the central particle size become more than half. It is preferable to use it.

FIG. 3 is a perspective view showing the discharge vessel 11 in the course of manufacturing for showing such a method of forming the discharge vessel 11.
The discharge vessel 11 in which the edge portions 16a, 16b, 16c, and 16d swell toward the outside of the discharge space S has a round tube 25 made of cylindrical silica glass and a rectangular shape to which an extraction rod 24 is attached. The drawing mold 23 is formed by drawing out the drawing mold in a state where the round pipe is heated and softened. In order to mold the edge portions 16a, 16b, 16c, and 16d so as to bulge outward, bulges are formed at the corners of the drawing die 23.

  As the processing step, first, the round tube 25 made of cylindrical silica glass is heated by a burner to such an extent that it can be easily deformed. Next, with the outer surface of the round tube 25 heated by a burner, the drawing die 23 is inserted and pushed into the inner tube. Since the drawing die 23 is larger than the cross section of the round tube 25, the round tube 25 is pushed and spread out on the square tube. For example, for the round tube 25 having a diameter of 30 mm, a drawing die 23 having a long side surface of 40 mm is used. Further, since the drawing die 23 is exposed to a high temperature, it is preferably formed of carbon. This is because if the pulling die 23 made of metal is used, the metal may adhere and mix as impurities into the inner surface of the discharge vessel 11 and the purity of the silica glass in the discharge vessel 11 may be lowered.

  Since the round tube 25 is baked into a square tube using the drawing die 23 having an area larger than the cross section of the round tube 25, the cross section of the formed discharge vessel 11 is a shape obtained by projecting the shape of the drawing die 23. It becomes. However, in consideration of the thermal expansion of the drawing mold itself, the shrinkage of the glass tube after drawing, etc., in fact, by forming a bulge in the corner of the drawing mold 23 in advance, the edge portion 16a of the discharge vessel 11, 16b, 16c and 16d are molded so as to swell outward.

  FIG. 4 is a graph showing the relationship between the film thickness of the ultraviolet reflecting film 20 and the light transmittance thereof. The vertical axis represents the transmittance [%], and the horizontal axis represents the film thickness [μm] of the ultraviolet reflecting film, showing the relationship. In addition, the transmittance | permeability shown on the vertical axis | shaft has shown the transmittance | permeability of the vacuum ultraviolet light with a wavelength of 172 nm. Further, it has been found that the same tendency is shown in the vacuum ultraviolet region in the wavelength range of 150 nm to 200 nm. From this graph, it can be seen that if the thickness of the ultraviolet reflective film 20 is increased, the transmittance of vacuum ultraviolet light decreases. It can be seen that when the film thickness of the ultraviolet reflecting film 20 is in the range of 10 μm or more, no vacuum ultraviolet light is transmitted.

  When the result of FIG. 4 is applied to the discharge vessel 11 of FIG. 2, if the ultraviolet reflecting film 20 is formed on the inner surface region of the discharge vessel 11 so as to have a sufficient film thickness, the wavelength generated in the discharge space S becomes 172 nm. Since the vacuum ultraviolet light having a peak cannot pass through the ultraviolet reflective film 20, the discharge vessel 11 formed through the ultraviolet reflective film 20 with respect to the discharge space S, specifically, the long side surface 12a, the short side surface 13a, The intensity of the vacuum ultraviolet light irradiated to 13b can be reduced. Therefore, it is possible to prevent the silica glass constituting the discharge vessel 11 from being irradiated with strong vacuum ultraviolet light, and to suppress the deterioration of the discharge vessel.

  In order to irradiate the object with excimer light generated in the discharge space S, the light emitting portion 17 in which the ultraviolet reflecting film 20 is not formed must be configured. Since the light emitting part 17 does not have the ultraviolet reflecting film 20, the silica glass constituting the discharge vessel 11 is directly irradiated with vacuum ultraviolet light. In addition, since the discharge vessel 11 has a rectangular cross section, the edge portions 16a, 16b, 16c, and 16d have a feature that stress tends to concentrate. Therefore, the light emitting portion 17 is formed on the long side surface 12b that does not include the edge portions 16a, 16b, 16c, and 16d, and the edge portions 16a, 16b, 16c, and 16d, which are likely to start damage, are vacuum-ultraviolet by the ultraviolet reflecting film 20. Protected from light. By adopting such a configuration, even in an excimer lamp using the discharge vessel 11 having a rectangular cross section, the discharge vessel 11 can be prevented from bursting.

  Further, the discharge vessel 11 has a central portion 121a, 121b of the long side surfaces 12a, 12b and a central portion 19a, 19b of the short side surfaces 13a, 13b with respect to the edge portions 16a, 16b, 16c, 16d. Therefore, in the inner surface regions of the edge portions 16a, 16b, 16c, and 16d, the ultraviolet reflective film 20 is formed thicker than the other inner surface regions of the discharge vessel 11. can do. Specifically, the ultraviolet reflective film 20 formed in the inner surface region of the edge portions 16a, 16b, 16c, and 16d has a film thickness that is at least 10 μm larger than the ultraviolet reflective film 20 formed in other regions. It has become. Therefore, since the film thickness of the ultraviolet reflecting film 20 formed on the inner surface region of the edge portions 16a, 16b, 16c, and 16d is secured at least 10 μm or more, vacuum ultraviolet light can be blocked almost completely, and the discharge vessel The 11 edge portions 16a, 16b, 16c, and 16d are not irradiated with the vacuum ultraviolet light generated in the discharge space S.

  That is, the film thickness of the ultraviolet reflecting film 20 formed on the inner surface region of the edge portions 16a, 16b, 16c, and 16d is larger than the film thickness formed on the other inner surface region of the discharge vessel 11. Yes. Therefore, in the edge portions 16a, 16b, 16c, and 16d that are likely to start breakage, the vacuum ultraviolet light is blocked by the ultraviolet reflective film 20, and the edge portions 16a, 16b, 16c, and 16d of the discharge vessel 11 are not irradiated with the vacuum ultraviolet light. In this way, it is possible to prevent the discharge vessel 11 from being ruptured by damage due to vacuum ultraviolet light.

Then, an example of the formation method of the ultraviolet reflective film 20 to the inner surface area | region of the discharge vessel 11 is demonstrated.
The ultraviolet reflecting film 20 can be performed, for example, by a method called “flow-down method”. First, a coating liquid to be poured inside the discharge vessel 11 is prepared. The coating liquid is composed of ultraviolet scattering particles, a binder, a dispersant, and a solvent. The ultraviolet scattering particles are, for example, silica particles and alumina particles, the binder contains tetraethyl orthosilicate, the dispersant is a silane coupling agent, and the solvent is ethanol.

By containing the dispersant in the coating liquid, the coating liquid can be easily gelled and adhered to the discharge vessel 11, and the ultraviolet scattering particles dispersed uniformly in the coating liquid can be fixed.
By containing a solvent in the coating liquid, the concentration of the ultraviolet scattering particles in the coating liquid can be adjusted.
The coating liquid is poured into the discharge vessel 11 and adhered to a predetermined region on the inner surface of the discharge vessel 11.

  First, the coating liquid is poured into the inner surface area of the short side surface 13a, and the coating liquid is adhered so that the film thickness of the central portion 19a on the short side surface 13a is 2 to 5 μm. Subsequently, the coating liquid is poured into the inner surface area of the short side surface 13b, and the coating liquid is adhered so that the film thickness of the central portion 19b on the short side surface 13b is 2 to 5 μm. In a state where the coating liquid is attached to the inner surface regions of the short side surface 13a and the short side surface 13b, the solvent is evaporated by natural drying. Furthermore, it is calcined by heating to 500 ° C. for 1 hour in an oxygen atmosphere. By calcining and fixing the coating liquid to the inner surface area of the short side surfaces 13a and 13b, the coating liquid does not buffer around the edge portions 16a and 16b and subsequently poured into the inner surface area of the long side surface 12a. Can be.

  Next, the coating liquid is poured into the inner surface region of the long side surface 12a to form the ultraviolet reflecting film 20. The coating liquid is attached so that the film thickness of the central portion 121a on the long side surface 12a is 20 to 30 μm, and the solvent is evaporated by natural drying in this state. At this time, due to the surface tension of the coating liquid, a phenomenon occurs in which the coating liquid is sucked up to the short side surfaces 13a and 13b in the vicinity of the edge portions 16a and 16b, so that the coating is also applied to the short side surfaces 13a and 13b side of the edge portions 16a and 16b. The liquid adheres thickly.

In this state, the discharge vessel 11 with the coating liquid attached also to the inner surface region of the long side surface 12a is naturally dried to evaporate the solvent, and further heated to 1000 ° C. for 1 hour in an oxygen atmosphere to perform the main baking. To do. When the coating liquid is baked, the dispersant is lost by heating, and only the ultraviolet scattering particles and the binder remain. The binder becomes silica and melts and adheres to the ultraviolet scattering particles, and increases the binding force between the particles and the discharge vessel 11.
Through the above process, the ultraviolet reflective film 20 having a larger film thickness can be formed in the inner surface region of the long side surface 12a than in the inner surface regions of the short side surfaces 13a and 13b. Furthermore, due to the fact that the long side surfaces 12a and 12b and the short side surfaces 13a and 13b of the discharge vessel 11 are processed into a curved shape and the surface tension of the coating liquid in the manufacturing process, the edges 16a, 16b, 16c and 16d In the inner surface region, the ultraviolet reflective film 20 can be formed so as to be thicker than other regions.

  The drawings used in the description of the present invention exaggerate the dimensions and the like of the thickness of the ultraviolet reflecting film 20 and the shape of the discharge vessel 11.

Schematic sectional view for explanation showing the structure of the excimer lamp of the present invention Schematic sectional view of the excimer lamp of the present invention The perspective view for showing the formation method of the discharge vessel of the excimer lamp of the present invention Graph showing the relationship between the film thickness of the UV reflective film and its light transmittance An explanatory perspective view showing a configuration of a conventional excimer lamp Cross-sectional view for explaining the deformation of the discharge vessel of the conventional excimer lamp

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Excimer lamp 11 Discharge vessel 12a, 12b Long side surface 13a, 13b Short side surface 14a, 14b End surface 15a, 15b Electrode 16a, 16b, 16c, 16d Edge part 17 Light emission part 20 Ultraviolet reflective film

Claims (3)

A discharge vessel having a rectangular cross-section surrounded by a long side surface opposite to each other and a short side surface connecting the long side surfaces, the long side surfaces of the discharge vessel facing each other; In the excimer lamp, a pair of electrodes are arranged on the short side surface, and the xenon gas is sealed inside the discharge vessel to generate excimer discharge in the discharge space.
The long side surface is curved in a direction in which a central portion of the long side surface faces the inside of the discharge space with respect to an edge portion connecting the long side surface and the short side surface,
On the inner surface of the discharge vessel is formed an ultraviolet reflective film whose central portion is curved in the direction toward the inside of the discharge space ,
The excimer lamp is characterized in that the ultraviolet reflective film is thicker at the edge portion than at the other inner surface of the discharge vessel.
  The short side surface is curved in the direction toward the inside of the discharge space with respect to an edge portion connecting the long side surface and the short side surface. The excimer lamp according to claim 1.   The excimer lamp according to claim 1, wherein the ultraviolet reflecting film includes silica particles and alumina particles.

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