JP5092700B2 - Excimer lamp - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an excimer lamp preventing illumination degradation in the vicinity of either end part of an axis direction of a discharge vessel, enlarging a substantial effective light-emitting length of a lamp, and avoiding elongation of the total lamp length. <P>SOLUTION: In the excimer lamp 1 provided with a pair of external electrodes 3, 4 facing each other through a discharge space 7 and arranged inside a discharge vessel 2 made of silica glass, an ultraviolet reflective film 5 is formed along an axis direction at a part of an inner surface of the discharge vessel 2, and also ultraviolet reflective films 5a, 5b are formed at end walls 2a, 2b of an axis direction end of the discharge vessel 2. And further, the end wall 2a at the axis direction end of the discharge vessel 2 is preferred to be slanted toward a light-extracting window 6 where an ultraviolet reflective film 5 of the discharge vessel 2 is not formed. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

The present invention relates to an excimer lamp that emits ultraviolet rays and is used in fields such as cleaning with ultraviolet rays, ashing, and film formation, and more particularly, to a discharge vessel made of silica glass via a discharge space. The present invention relates to an excimer lamp in which electrodes are arranged.
This excimer lamp encloses a discharge gas in a discharge vessel and applies an alternating high voltage between external electrodes through the discharge vessel to generate a dielectric barrier discharge, which emits excimer light, which is vacuum ultraviolet light. To do.

By the way, in an internal electrode type discharge lamp, an ultraviolet reflecting film is formed in the discharge vessel, and the ultraviolet rays generated in the discharge vessel are reflected to efficiently from the light extraction window formed in a part of the discharge vessel. A device that emits ultraviolet rays has been proposed.
Japanese Patent No. 2626144

However, there is no known external electrode type excimer lamp in which an ultraviolet reflecting film is formed in a discharge vessel.
Then, when an ultraviolet reflecting film as in Patent Document 1 is applied to a known external electrode excimer lamp, a lamp structure as shown in FIG. 5 is assumed.
In the figure, an excimer lamp 1 includes a flat and long rectangular discharge vessel 2 made of silica glass that transmits ultraviolet rays, and a pair of opposed flat walls on a pair of upper and lower flat walls via a discharge space 7. External electrodes 3 and 4 are provided, respectively.
An ultraviolet reflection film 5 is formed on a part of the inner surface of the discharge vessel 2 along the axial direction, and a lower portion where the ultraviolet reflection film 5 is not formed functions as a light extraction window 6.

  In such an excimer lamp, the ultraviolet rays generated in the discharge space 7 are reflected by the ultraviolet reflecting film 5 and radiated to the outside from the lower light extraction window 6 together with the ultraviolet rays directly directed from the discharge space 7. Thereby, ultraviolet rays are effectively radiated to the outside, and an improvement in ultraviolet illuminance is expected.

Incidentally, the excimer lamp as shown in FIG. 5 has a disadvantage that the illuminance at both ends in the axial direction is lower than the illuminance in the vicinity of the center due to the structure.
In other words, the effective light emission length of the lamp is shorter than the total length of the lamp, and if the sufficient effective light emission length is obtained, the total length of the lamp becomes long. In view of LCD substrate cleaning, which is the main application of this type of lamp, the enlargement of the lamp becomes more serious when it is applied to the recent enlargement of the substrate.

  In view of the above problems, the present invention provides an excimer lamp that prevents a decrease in illuminance in the vicinity of both ends in the axial direction of the discharge vessel, increases a substantial effective light emission length of the lamp, and avoids an increase in the total length of the lamp. It is to provide.

  In an excimer lamp in which a pair of external electrodes facing each other through a discharge space is arranged on a discharge vessel made of silica glass, an ultraviolet reflecting film is formed along a part of the inner surface of the discharge vessel along the axial direction, An ultraviolet reflecting film is also formed on the end wall at the axial end of the discharge vessel.

  Furthermore, the end wall at the axial end of the discharge vessel is inclined toward the light extraction window where the ultraviolet reflecting film of the discharge vessel is not formed.

  According to the present invention, the ultraviolet reflection film is formed on the inner surface of the discharge vessel, and the ultraviolet reflection film is also formed on both end walls in the axial direction of the discharge vessel, so that the ultraviolet illuminance of the entire lamp can be improved. The illuminance at both ends of the discharge vessel is increased, and the substantial effective light emission length of the lamp can be increased.

  Embodiments of the present invention will be described below with reference to the drawings.

<Example 1>
FIG. 1 is a cross-sectional view of Embodiment 1 of the present invention.
The excimer lamp 1 has a pair of opposed external electrodes 3 and 4 on upper and lower flat walls of a flat rectangular discharge vessel 2 made of silica glass.

For example, the external electrodes 3 and 4 are made of a lattice-shaped metal, and are formed on the discharge vessel 2 by means of screen printing, vacuum deposition, sputtering, or the like. As the material, for example, aluminum, nickel, gold or the like is used.
One of the external electrodes 3 and 4 is a high voltage electrode (external electrode 3) connected to a high voltage side of a power supply device (not shown), and the other is a ground electrode (external electrode 4). In general, the ground electrode 4 is disposed opposite to a target object (not shown).
An ultraviolet reflection film 5 is formed along the axial direction on the inner surface of the discharge vessel 2 on the high-voltage electrode 3 side, and the ground electrode 4 side of the discharge vessel 2 facing the object to be processed (not shown) Is not formed, and functions as the light extraction window 6. That is, the ultraviolet rays generated in the discharge vessel 2 are reflected by the ultraviolet reflecting film 5 and are emitted to the outside through the light extraction window 6 together with the ultraviolet rays emitted directly downward from the discharge space 7.

  In addition to the above, ultraviolet reflection films 5a and 5b are also formed on the inner surfaces of the end walls 2a and 2b at both axial ends of the discharge vessel 2.

  By adopting such a configuration, ultraviolet rays are reflected also at the ends of the discharge vessel 2 by the ultraviolet reflecting films 5a and 5b formed on the end walls 2a and 2b at both ends of the discharge vessel 2, so that the vicinity of both ends is provided. Thus, there is no effect of reducing the illuminance of ultraviolet rays, and the effect of expanding the region where the illuminance is uniform is obtained.

The ultraviolet reflecting film 5 (5a, 5b) is formed by laminating a plurality of light-transmitting fine particles, and has a thickness of, for example, 10 to 500 μm. When the ultraviolet rays reach the microparticles on the surface of the ultraviolet reflecting film, a part is reflected by the surface of the particles, and a part is refracted and transmitted into the particles. A part of the light transmitted through the inside of the particles is absorbed, but most of the light is transmitted and refracted when it is emitted from the inside again. By laminating light-transmitting fine particles and repeatedly causing such reflection and refraction, the ultraviolet rays are scattered in the direction opposite to the incident direction, and this becomes reflected light.
As described above, since the ultraviolet reflecting film utilizes light transmittance, light reflection of fine particles, and diffuse reflection due to refraction, it is preferable to use a material having a high refractive index, for example, silica or alumina as the fine particles. In particular, silica glass bulbs are widely used for lamps that emit ultraviolet rays. An ultraviolet reflecting film using silica of the same material as fine particles has high adhesion to silica glass because there is no difference in thermal expansion coefficient from silica glass. In addition, materials that absorb ultraviolet rays, such as titanium, zirconium, and these compounds are not adopted as the fine particles. However, titanium or zirconium may be mixed as impurities in the ultraviolet reflecting film.

  Further, in order to efficiently diffuse and reflect ultraviolet rays, the particle size of the fine particles of the ultraviolet reflecting film 5 (5a, 5b) is, for example, in the range of 0.01 to 20 μm, and the central particle size is, for example, 0.1 to 10 μm is preferable, and 0.3 to 3 μm is more preferable.

<Example 2>
Another embodiment 2 is shown in FIG. In FIG. 2, the end wall 2 a at the axial end of the discharge vessel 2 is inclined toward the light extraction window 6 in which the ultraviolet reflecting film 5 of the discharge vessel 2 is not formed.
That is, the end wall 2 a is inclined at an angle θ of less than 90 ° with respect to the lower flat wall of the discharge vessel 2 that functions as the light extraction window 6.
Needless to say, the opposite end wall 2b (not shown) has the same configuration.
Of course, an ultraviolet reflecting film 5a (5b) is formed on these end walls 2a (2b).

  By doing so, more ultraviolet rays reflected by the ultraviolet reflecting film 5a (5b) formed on the end wall 2a (2b) are emitted from the light extraction window 6 to the outside.

  An experimental example carried out to confirm the effect of the present invention will be described with reference to FIG.

<Lamp of the present invention>
An excimer lamp having the structure shown in FIG. 1 was manufactured. The discharge vessel 2 made of silica glass has a total length of 320 mm, a vertical (thickness) direction dimension of 15 mm, a horizontal (width) direction dimension of 42 mm, and a wall thickness of 2.5 mm. The compositions of the ultraviolet reflecting films 5, 5a and 5b are the same and are as shown below.
Silica particles: particle size 0.4 μm to 1.5 μm, center diameter: 0.7 μm
Alumina particles: 0.2 μm to 0.5 μm, center diameter: 0.3 μm
Content of alumina particles: 10% by weight
The thickness of the ultraviolet reflecting film 5 was 40 μm. The firing temperature was 1100 ° C. External electrodes 3 and 4 were formed on the outer surface of the discharge vessel 2 using gold by screen printing. The dimensions of the electrode are 300 mm in total length and 33 mm in the lateral (width) direction. Xenon was sealed in the discharge vessel 2 at 40 kPa as a discharge gas.

<Comparative lamp>
In order to verify the ultraviolet illuminance of the lamp of the present invention, a lamp shown in FIG. 5 was manufactured as a comparative example.
In the lamp of this comparative example, as shown in FIG. 5, the ultraviolet reflecting film 5 is formed only on the inner surface of the discharge vessel 2 on the high voltage side external electrode 3 side, and the end walls 5a at both ends of the discharge vessel 2 are It is not formed in 5b. Other configurations are the same as those in FIG.

  In measuring the illuminance distribution, the excimer lamp 1 is housed in a housing (not shown), the atmosphere in the housing is purged with nitrogen gas, the excimer lamp is lit at an AC high voltage of 5 kV, and the discharge vessel 2 The wavelength region of 150 to 200 nm was measured by an ultraviolet illuminometer that scans a location 1 mm away from the light extraction window 6.

  FIG. 3 shows the relative illuminance distribution in the lamp axis direction. The position of 0 mm in FIG. 3 corresponds to the position of the end wall 5a at the left end in the axial direction of the lamp, and the position of 320 mm corresponds to the end wall 5b at the right end. Here, Table 1 below shows the effective light emission length of each lamp when the effective light emission length is defined as a portion where the ultraviolet relative illuminance is secured to 80% or more.

As is apparent from the above, when the ultraviolet reflecting films 5a and 5b are also formed on the end walls 2a and 2b at both ends of the discharge vessel 2, the ultraviolet illuminance at both ends of the lamp is increased as compared with a comparative lamp without this. It can be seen that the effective light emission length of the lamp is increased.
Further, since the ultraviolet illuminance increased by the ultraviolet reflecting films 5a and 5b on the both end walls 2a and 2b is within a range of several centimeters from the end walls, the maximum value of the ultraviolet illuminance near the center of the lamp does not increase, and the effective light emission length is large. Become.
In other words, the excimer lamp in which the ultraviolet reflecting films are formed on both end walls can shorten the length of the discharge space necessary to obtain the same effective light emission length as the excimer lamp in which the ultraviolet reflecting film is not formed here. Therefore, the overall length of the lamp can be shortened.

<Example 3>
In the first and second embodiments of the present invention, the case where the discharge vessel 2 has a flat rectangular shape has been described. However, the present invention is not limited to this, and the discharge vessel 2 has a double cylindrical shape as shown in FIG. Of course, it may be.
That is, the discharge vessel 2 of the excimer lamp 1 includes an outer tube 2c and an inner tube 2d, which are sealed with each other by end walls 5a and 5b at axial ends, and a discharge space 7 is formed therebetween.
Then, an ultraviolet reflecting film 5 is formed along the axial direction on a part of the inner surface of the outer tube 2c, and an ultraviolet reflecting film 5 is formed around the outer tube 2d. Further, end walls 2a at both ends, UV reflection films 5a and 5b are also formed on 2b.

  Also in the third embodiment, the ultraviolet rays reflected by the ultraviolet reflecting film 5 are radiated to the outside from the light extraction window 6 in which the ultraviolet reflecting film 5 of the outer tube 2c is not formed, but at this time, the end walls 2a, Similar to the first and second embodiments, the 2b ultraviolet reflection films 5a and 5b increase reflection at both ends, and can prevent a decrease in illuminance at this portion.

In this embodiment, the ultraviolet reflecting film 5 is described as being formed on the outer tube 2c and the inner tube 2d, but it is not formed on the inner tube 2d but only on the inner surface of the outer tube 2c. It may be what you did.
Moreover, although the cylindrical thing was shown as a cylindrical shape of the outer tube | pipe 2c and the inner tube | pipe 2d which comprise the discharge vessel 2, a rectangular tube shape may be sufficient.

Sectional drawing of Example 1 of this invention. The fragmentary sectional view of Example 2 of the present invention. The graph showing the effect of this invention. Sectional drawing of Example 3 of this invention. (A) is a cross-sectional view. (B) is AA sectional drawing of (a). Sectional drawing showing a comparative example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Excimer lamp 2 ... Discharge vessel 2a, 2b ... End wall 3, 4 ... External electrode 5, 5a, 5b ··· UV reflective film 6 ··· Light extraction window 7 ··· Discharge space

Claims (2)

In an excimer lamp in which a pair of external electrodes facing each other through a discharge space are arranged in a discharge vessel made of silica glass,
An ultraviolet reflecting film is formed over the entire length along the axial direction on the inner surface of the discharge vessel, and an ultraviolet reflecting film is also formed on the end wall at the axial end of the discharge vessel,
An excimer lamp , wherein the discharge vessel is formed with a light extraction window on which the ultraviolet reflecting film is not formed .

  2. The excimer lamp according to claim 1, wherein an end wall at an axial end of the discharge vessel is inclined toward a light extraction window in which an ultraviolet reflection film of the discharge vessel is not formed.

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