JP2005259380A - Ultraviolet ray irradiation treatment device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ultraviolet ray irradiation treatment device for dispensing with a light take-out window having front glass and greatly improving the utilization efficiency of ultraviolet rays. <P>SOLUTION: In the ultraviolet ray irradiation treatment device for irradiating an object to be treated with ultraviolet rays, the device has a discharge lamp and a reflector. The discharge lamp has a first mesh-like electrode and a second one that oppose each other. The first mesh-like electrode is arranged at the side of the object to be treated. The reflector is arranged at the side of the second mesh-like electrode so that a space section is formed at an area to the discharge lamp. Gas jetting out of a gas jet-out hole provided at the reflector is introduced to the space section. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an excimer lamp that emits light in the vacuum ultraviolet region, which is used as an ultraviolet light source in the fields of photocleaning, photoashing, and the like, and an ultraviolet irradiation treatment apparatus using the excimer lamp.

  Silent discharge excimer lamps are provided with a pair of opposed electrodes in a discharge vessel filled with a discharge gas such as xenon (Xe) or krypton (Kr), both of which are not in contact with the discharge gas or one of them is It is a light source that can radiate ultraviolet rays peculiar to gas with high efficiency in a contact manner.

Conventionally, in an excimer lamp irradiation apparatus using vacuum ultraviolet light having a wavelength of 172 nm emitted from Xe ₂ , a box-shaped lamp house filled with a gas (protective gas) having good transmittance of vacuum ultraviolet light such as nitrogen A Xe ₂ excimer lamp and a light reflector are installed inside, and a light extraction window with good transmittance for vacuum ultraviolet light, such as synthetic quartz glass, is attached to the light extraction surface of the lamp house. Was irradiated on the irradiated object.

  That is, the utilization efficiency of vacuum ultraviolet light has been improved by installing a light reflector and a lamp in a lamp house completely replaced with nitrogen gas or the like. As a technique related to the present invention, there is a technique in which a discharge lamp having a substantially cylindrical outer shape is filled with nitrogen gas in a lamp house provided with a light extraction window (for example, Patent Document 1).

  FIG. 3 is a diagram showing the configuration disclosed in Patent Document 1. Cylindrical dielectric barrier discharge lamps (excimer lamps) 41 a, 41 b and 41 c are accommodated in the lamp house 21. The lamp house 21 is provided with a light extraction window 20, and a space 26 between the dielectric barrier discharge lamps 41a, 41b and 41c and the light extraction window 20 is filled with nitrogen gas.

  With such a configuration, the part of the vacuum ultraviolet light emitted from the dielectric barrier discharge lamps 41a, 41b and 41c toward the adjacent dielectric barrier discharge lamp hits the V-shaped light reflectors 43 and 45. The light is reflected, the traveling direction of the light is changed downward, and is emitted from the light extraction window 20. In this case, the vacuum ultraviolet light emitted from the dielectric barrier discharge lamps 41a, 41b and 41c passes through the space 26 between the dielectric barrier discharge lamps 41a, 41b and 41c and the light extraction window 20, and this space 26 Is filled with nitrogen gas, there is almost no attenuation of light intensity due to absorption.

  Accordingly, the light extraction window 20 emits the total of the portion of the vacuum ultraviolet light emitted from the dielectric barrier discharge lamps 41a, 41b and 41c toward the light reflecting plates 43 and 45 in the horizontal direction and the portion directly directed to the irradiated object. The light extraction window 20 becomes a substantially planar vacuum ultraviolet light source.

  As another conventional method, as shown in FIG. 4, an excimer lamp having a thin box-like discharge vessel is used, and vacuum ultraviolet light radiated from the lamp does not pass through the front glass and nitrogen gas. The object was irradiated directly. For example, such a conventional example is described in Japanese Patent Laid-Open No. 2000-260396 (Patent Document 2). In FIG. 4, 12 is a discharge vessel, 13 is an ultraviolet light irradiation surface, 14 is a stationary electrode (solid electrode) arranged so as to cover almost the entire surface of the discharge vessel, 15 is a discharge gas, and 16 is a mesh shape. An electrode 17 is a high-frequency voltage for lighting. In this method, the surface of the lamp from which the vacuum ultraviolet light is extracted is substantially flat, and the distance from the object to be irradiated is desired to be as small as possible because the vacuum ultraviolet light is absorbed when an air layer is present.

Japanese Registered Patent No. 2854255 JP 2000-260396 A

  By the way, in the conventional method described in Patent Document 1, the equipment is large in size, the front glass is expensive, and the front glass needs to be periodically replaced due to deterioration due to irradiation with vacuum ultraviolet light. There was a problem.

  In addition, the lamp described in Patent Document 2 has a mesh electrode on the surface facing the object to be irradiated, and a solid electrode that does not transmit any light on the opposite surface (attached to almost the entire area of one surface of the lamp. A metal electrode that is not transparent to ultraviolet light). For example, in order to increase the utilization efficiency of vacuum ultraviolet light, when a metal having a good reflectivity of vacuum ultraviolet light such as Al is used for a solid electrode and also serves as a reflection surface, a dielectric surface such as quartz constituting a discharge lamp In this method, electrodes are directly formed by means such as vapor deposition, or a metal plate is applied to the dielectric surface.

  In the former, peeling between the electrode and the dielectric becomes a problem, and in the latter, the contact distance between the electrode and the dielectric becomes a problem.

  That is, in the former, a vapor deposition film having a thin film thickness is basically used as the electrode film. Therefore, when the film disappears due to oxidation / degradation due to active oxygen generated at the time of lighting, the function as an electrode may not be achieved. Furthermore, when the vapor deposition film also serves as a reflecting surface, the reflectance is lowered, and the function as the reflecting surface may not be achieved.

  As a specific example, especially when the dielectric material is quartz, the thermal expansion coefficient of the aluminum that is quartz and the electrode material does not match. Has a problem of falling off the dielectric.

  On the other hand, in the latter case, when the electrode is deformed due to contamination of the dielectric material due to sputtering of the electrode material or heat generated in the discharge lamp, not only does it function as an electrode, but also vacuum ultraviolet light is generated by the air present in the voids generated by the deformation. Is absorbed, and the function as a reflector is not achieved.

  As described above, when an electrode having a reflection function is directly deposited or contacted with the discharge lamp, various problems may occur.

  The present invention provides a compact and low-cost ultraviolet irradiation processing apparatus that greatly improves the utilization efficiency of vacuum ultraviolet light without causing these problems.

  An ultraviolet irradiation processing apparatus according to the present invention is an ultraviolet irradiation processing apparatus for irradiating a workpiece with ultraviolet rays, wherein the ultraviolet irradiation processing apparatus includes a discharge lamp and a reflector, and the discharge lamp faces the first. A first mesh electrode and a second mesh electrode, wherein the first mesh electrode is disposed on an object to be processed, and the reflector is the second mesh electrode. It is arranged on the electrode side so as to form a space portion with the discharge lamp, and the space portion is configured such that gas ejected from a gas ejection hole provided in the reflector is introduced. It is characterized by that.

  That is, the ultraviolet irradiation processing apparatus of the present invention has a first mesh electrode on the irradiation surface side of the discharge lamp and a second mesh shape on the opposite side (non-irradiation surface side) as shown in FIG. An electrode is provided, and a reflector 7 for reflecting vacuum ultraviolet light is provided on the non-irradiation surface side of the discharge lamp with an appropriate interval d. The reflector 7 includes a gas ejection hole 9 for replacing air in the space between the discharge lamp 2 and the reflector 7 with gas. Further, the distance d between the discharge lamp 2 and the reflecting fixture 7 is optimized according to the shape of the discharge lamp and the gas flow rate. As a result, the vacuum ultraviolet light emitted from the non-irradiated surface side to the outside of the lamp reaches the reflector 7 with almost no attenuation, is reflected by the reflective surface, passes through the gas layer again, enters the discharge lamp, and is irradiated. Radiated from the surface side.

  The present invention eliminates the need for providing a light extraction window having a front glass by the above method, and reverses the traveling direction of the vacuum ultraviolet light emitted in the direction opposite to the irradiation surface side by 180 ° to use the vacuum ultraviolet light. The present invention provides a compact and low-cost ultraviolet irradiation processing apparatus with greatly improved efficiency.

  Since the ultraviolet irradiation processing apparatus of the present invention can effectively use the vacuum ultraviolet light emitted in the direction opposite to the ultraviolet light irradiation surface side of the discharge lamp, the utilization efficiency of the vacuum ultraviolet light can be greatly improved. Furthermore, since a lamp house having a front glass and filled with nitrogen gas is not required, the apparatus can be made compact and inexpensive. Further, since the discharge lamp and the reflector are not in direct contact with each other, there is no problem of peeling or deformation of the reflecting surface, and a highly reliable ultraviolet irradiation processing apparatus can be provided.

The ultraviolet irradiation processing apparatus of this invention is demonstrated referring drawings. FIG. 1 is a sectional view showing an ultraviolet irradiation treatment apparatus of the present invention. As shown in FIG. 1, the discharge lamp 2 has a substantially rectangular cross-sectional shape in a plane perpendicular to the longest axis direction, and a first mesh electrode 4 is formed on the irradiation surface side from which vacuum ultraviolet light is extracted. A second mesh electrode 3 is formed on the non-irradiated surface side opposite to the surface. The material of the discharge lamp 2 is MgF ₂ , synthetic quartz, or the like as a material that transmits vacuum ultraviolet light well. The thickness of the discharge lamp 2 is normally about 1 to 2 mm. The discharge lamp 2 is filled with, for example, a Xe-based gas as a discharge gas. When the sealed gas is a Xe-based gas, vacuum ultraviolet light having a center wavelength of 172 nm is obtained.

In addition, as the discharge gas, Kr, Ar / F, Kr / Cl, Kr / F, or the like can be used. When these discharge gases are used, ultraviolet light having center wavelengths derived from Kr ₂ , ArF, KrCl, and KrF having 146 nm, 193 nm, 222 nm, and 248 nm, respectively, is obtained. As described above, the wavelength of the ultraviolet light obtained varies depending on the type of the discharge gas, and therefore the sealed gas may be selected in accordance with the purpose.

  When the discharge lamp 2 is made of synthetic quartz and a vapor deposition film is used as an electrode, for example, chromium is vapor-deposited on the synthetic quartz surface, and then platinum, gold, nickel, or the like is vapor-deposited thereon. Thereby, a stable electrode can be formed even in an atmosphere of active oxygen generated by vacuum ultraviolet light emitted from the lamp. A mesh electrode can be completed by forming a mesh pattern on the electrode thin film by etching with an acid, for example.

  The ultraviolet irradiation processing apparatus as shown in FIG. 1 is completed by combining the discharge lamp 2 configured as described above and the reflector 7. That is, a reflector 7 having a function of ejecting a protective gas having a good vacuum ultraviolet light transmittance, for example, nitrogen gas 6, is disposed on the non-irradiated surface side of the discharge lamp 2 at an appropriate interval d. Then, the interval d is optimized according to the shape of the discharge lamp 2 and the flow rate of the nitrogen gas so that the air in the space between the discharge lamp 2 and the reflector 7 is replaced with nitrogen gas. Thereby, the vacuum ultraviolet light radiated out of the discharge lamp from the non-irradiated surface side having the second mesh electrode 3 reaches the reflector 7 with almost no attenuation, and is reflected by the reflector 8 and then again nitrogen gas. The light passes through the layers, enters the discharge lamp 2, and is emitted from the irradiation surface side having the first mesh electrode 4.

  Thus, the ultraviolet irradiation processing apparatus according to the present invention does not require the use of a lamp house having a light extraction window and filled with nitrogen gas as in the prior art, and vacuum ultraviolet radiation emitted in the direction opposite to the irradiation surface side. Since the light traveling direction can be reversed 180 ° and taken out from the irradiation surface side, the utilization efficiency of vacuum ultraviolet light can be greatly improved, and the apparatus can be made very compact and low cost. Furthermore, since the discharge lamp and the reflector are not in direct contact, there is no problem of peeling or deformation of the reflecting surface, and a highly reliable ultraviolet irradiation processing apparatus can be provided.

  In FIG. 1, the dimension of the discharge lamp 2 in the cross section is about 2 mm thick, the width of the outer dimension is about 35 mm, the height is about 12 mm, and the length in the direction perpendicular to the paper surface is about 420 mm. In addition, as a dimension of the reflector 7, the width of the reflector 8 made of an electrolytically polished aluminum plate was about 40 mm. Nitrogen gas was used as the protective gas 6, and the nitrogen gas ejection holes 9 having a diameter of about 5 mm were arranged in the reflector plate 8 in the longitudinal direction of the lamp at approximately 30 mm intervals in the center of the lamp in the width direction. An experiment was conducted to measure the relative intensity of ultraviolet light when the distance d between the reflecting plate 8 and the discharge lamp 2 and the nitrogen gas flow rate were changed. The nitrogen gas flow rate was changed in the range of 0 to 10 liters / minute as the flow rate flowing through each ejection hole. The lamp was turned on under the above conditions, and the relative illuminance of ultraviolet light on the irradiated surface at a distance of 2 mm from the ultraviolet irradiation surface of the discharge lamp 2 was measured.

  The measurement result of the ultraviolet relative illuminance on the surface to be irradiated is shown in FIG. FIG. 2 shows the relationship between the relative illuminance of vacuum ultraviolet light having a wavelength of 172 nm on the irradiated surface and the gas flow rate, with the distance d between the reflector 8 and the discharge lamp 2 as a parameter. 2 that the irradiance increases as the distance d between the reflector 8 and the discharge lamp 2 decreases and the flow rate of the protective gas increases.

  In particular, high irradiance can be obtained by setting the distance d between the reflecting plate 8 and the discharge lamp 2 to 6 mm or less, preferably 4 mm or less. Furthermore, if the gas flow rate is 2 liters / minute or more, and preferably 6 liters / minute or more, in which the effect of increasing irradiance is exhibited, the utilization efficiency of vacuum ultraviolet light is greatly increased and can be improved by about 40%. is there. However, even if the gas flow rate is increased excessively, the irradiance is saturated and does not change. Therefore, it is wise to set the gas flow rate to a value in the vicinity of saturation of irradiance in order to eliminate waste of gas.

It is sectional drawing which shows the ultraviolet irradiation processing apparatus which concerns on this invention. In the ultraviolet irradiation processing apparatus which concerns on this invention, it is a graph which shows the relationship between a gas flow rate and the ultraviolet light relative illumination intensity in a to-be-irradiated surface. It is sectional drawing which shows an example of the conventional ultraviolet irradiation processing apparatus. It is an external view which shows an example of the conventional vacuum ultraviolet light source.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Discharge gas 2 Discharge lamp 3 2nd mesh electrode 4 1st mesh electrode 5 To-be-processed object 6 Protective gas 7 Reflector 8 Reflector 12 Discharge lamp 13 Ultraviolet irradiation surface 14 Solid electrode 16 Mesh electrode 41 Excimer Lamp 20 UV extraction window 22 Irradiation tool 24 Gas introduction hole 25 Gas discharge hole

Claims (1)

In an ultraviolet irradiation processing apparatus for irradiating an object to be processed with ultraviolet rays, the ultraviolet irradiation processing apparatus includes a discharge lamp and a reflector, and the discharge lamp has a first mesh electrode and a second mesh facing each other. And an electrode
The first mesh electrode is disposed on the workpiece side, and the reflector is disposed on the second mesh electrode side so as to form a space between the discharge lamp and the discharge lamp. The ultraviolet irradiation processing apparatus is characterized in that a gas ejected from a gas ejection hole provided in the reflector is introduced into the space portion.

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