JP4221561B2 - Excimer lamp - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an excimer lamp which is emitting the vacuum ultraviolet rays by a dielectric barrier discharge is used to light cleaning or light ash, etc. By applying a voltage to the discharge vessel enclosing a discharge gas therein.
[0002]
[Prior art]
The excimer lamp emits high-energy vacuum ultraviolet rays having a center wavelength of 172 nm when, for example, xenon is used as a discharge gas for excimer light emission. Therefore, in place of a low-pressure mercury lamp that mainly emits ultraviolet rays having wavelengths of 185 nm and 254 nm, it is often used as a light source of an ultraviolet irradiation device that performs precision cleaning (light cleaning) of a glass substrate or a semiconductor wafer of a liquid crystal display device. It has become. Vacuum ultraviolet rays refer to ultraviolet rays having a wavelength in the range of 200 nm or less and 50 nm or more. Since this vacuum ultraviolet ray is absorbed by oxygen in the air and generates ozone, the vacuum ultraviolet ray transmitted through the generated ozone by irradiating the surface of the processing object such as the glass substrate of the liquid crystal display device in this air. By the synergistic effect, cleaning can be performed by decomposing and scattering organic substances on the surface of the object to be processed.
[0003]
When the excimer lamp has a wavelength of 172 nm, a discharge gas for excimer light emission is sealed in a discharge vessel made of synthetic quartz glass, and a high frequency voltage is applied to the discharge gas to cause a dielectric barrier discharge, thereby generating a vacuum. It emits ultraviolet rays. Conventionally, a discharge vessel in which a discharge gas is sealed in a double-structured cylindrical tube or a small-diameter cylindrical tube is often used (see, for example, Patent Document 1). Further, an excimer lamp using a rectangular box-shaped discharge vessel instead of the double cylindrical discharge vessel has been developed (see, for example, Patent Document 2).
[0004]
Since vacuum ultraviolet light having a wavelength of 172 nm is extremely high in energy, fine cracks and cracks are generated due to deterioration when synthetic quartz glass is subjected to strong irradiation of this vacuum ultraviolet light for a long time. The excimer lamp often loses its life due to poor lighting because the deterioration of the synthetic quartz glass impairs the hermeticity of the discharge vessel. In addition, since synthetic quartz glass deteriorates faster as the temperature is lower, a protective layer that absorbs and / or reflects vacuum ultraviolet rays is formed on the inner surface of the cooling part of the discharge vessel. An invention for preventing the life of the excimer lamp from being shortened due to the early deterioration of the quartz glass has already been made (see, for example, Patent Document 3).
[0005]
[Patent Document 1]
Japanese Patent Laid-Open No. 2001-243920 (FIG. 4)
[Patent Document 2]
JP 2000-260396 A [Patent Document 3]
JP-A-2002-93377 [0006]
[Problems to be solved by the invention]
Recently, however, as shown in FIG. 3, an excimer lamp has been developed in which the rectangular box-shaped discharge vessel 1 is formed in a very long shape in the front and rear. This discharge vessel 1 has both ends of a synthetic quartz glass tube having a length of 1 m or more before and after forming a horizontally long thin square having a vertical cross-sectional height of several tens of millimeters and a lateral width of several tens of millimeters. Closed and filled with xenon gas. The discharge vessel 1 has electrodes 2 and 3 formed by patterning metal thin films on flat upper and lower surfaces. The electrode 2 on the upper surface of the discharge vessel 1 is formed so as to cover almost the entire flat upper surface, while the electrode 3 on the lower surface is formed in a mesh pattern, and vacuum ultraviolet rays are applied downward from the mesh space. It can be irradiated. Since the vacuum ultraviolet ray is absorbed by oxygen, it is attenuated in the air and can reach only a short distance. For example, when the wavelength is 172 nm, it can reach only a distance of about 10 mm or less. Therefore, in order to irradiate as much area as possible with the vacuum ultraviolet rays radiated by the excimer lamp, it is necessary to irradiate from the flat surface having the largest area in the discharge vessel 1. A vacuum ultraviolet ray is irradiated downward from the gap.
[0007]
However, the intensity of the vacuum ultraviolet rays emitted from the excimer lamp becomes stronger as the distance of the discharge space in the discharge vessel 1 becomes longer because there is no self-absorption in excimer emission. For this reason, when using the extremely long discharge vessel 1 as described above, the vacuum ultraviolet rays extracted downward as the actual irradiation light are radiated from the discharge space of a short distance of tens of mm or less in the vertical direction. Thus, since the vacuum ultraviolet rays radiated in the front-rear direction are emitted from the discharge space having a distance of 1 m or more, the ultraviolet rays have extremely high ultraviolet intensity.
[0008]
Therefore, the excimer lamp that irradiates vacuum ultraviolet rays in the shortest direction of the discharge vessel 1 has high intensity of vacuum ultraviolet rays radiated in directions other than the shortest direction, and in particular, the intensity of vacuum ultraviolet rays radiated in the longest direction is extremely strong. Therefore, there has been a problem that the deterioration of the wall plate at the end portion in these directions progresses at an early stage, and the life is remarkably shortened.
[0009]
The present invention has been made in order to cope with such circumstances, to provide an excimer lamp to prevent degradation by a wall plate of the longest edge or the like of the discharge vessel of the excimer lamp vacuum ultraviolet rays hardly transmitted The purpose is that.
[0010]
[Means for Solving the Problems]
The excimer lamp according to claim 1 is constituted by a dielectric that is longest in the front and back and shortest in the top and bottom, and has substantially flat top and bottom wall plates facing each other in the top and bottom, and substantially parallel to each other, and transmits vacuum ultraviolet rays. A closed vessel, which includes a discharge vessel filled with a discharge gas for excimer emission, and electrodes formed on the outer surfaces of the upper and lower wall plates of the discharge vessel. In the excimer lamp, the vacuum ultraviolet ray protection layer is formed on the inner surface of at least the front and rear end wall plates of the front and rear ends of the discharge vessel.
[0011]
According to the first aspect of the present invention, the vacuum ultraviolet protective layer is formed on the inner surfaces of the front and rear end wall plates at both ends in the front-rear direction where the intensity of the emitted vacuum ultraviolet light is strongest. It becomes possible to prevent the end wall plate from prematurely deteriorating. In addition, since the intensity of the vacuum ultraviolet rays in the left and right directions is stronger than in the vertical direction, this vacuum ultraviolet protective layer is also formed on the inner surfaces of the left and right side wall plates to prevent the deterioration of these left and right side wall plates. Also good. The vacuum ultraviolet protective layer is a layer for protecting the back wall plate against the irradiation of vacuum ultraviolet rays. For example, a layer that absorbs vacuum ultraviolet rays, a layer that reflects the vacuum ultraviolet rays, and absorbs and reflects them simultaneously. Layers or the like are used.
[0012]
Note that the orthogonal directions of front and rear, upper and lower, and left and right shown in this specification are merely used for convenience to express the relationship between the respective directions, so the actual arrangement of the excimer lamp is arbitrary. is there.
[0015]
The excimer lamp according to claim 2 is longest in the front and back and shortest in the top and bottom, and substantially flat top and bottom wall plates facing each other in the top and bottom have a shape substantially parallel to each other, and at least the bottom wall plate transmits vacuum ultraviolet rays. In addition, at least the front and rear end wall plates at both front and rear ends are sealed containers made of a dielectric material having a higher reflectivity of vacuum ultraviolet rays than the lower wall plate, and a discharge gas filled with a discharge gas for excimer emission is contained therein. A container and electrodes formed on the outer surfaces of the upper and lower wall plates of the discharge vessel are provided, and vacuum ultraviolet rays are irradiated downward through the lower wall plate.
[0016]
According to the invention of claim 2 , the front and rear end wall plates at both ends in the front-rear direction where the intensity of the radiated vacuum ultraviolet rays is the strongest reflect the vacuum ultraviolet rays. It becomes possible to prevent the deterioration. Further, since the intensity of the vacuum ultraviolet rays in the left and right directions is stronger than that in the vertical direction, the left and right side wall plates may also reflect the vacuum ultraviolet rays to prevent the deterioration of the left and right side wall plates.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
[0018]
1 and 2 show an embodiment of the present invention. FIG. 1 is a perspective view in which the long central portion of the excimer lamp is omitted, and FIG. 2 is a schematic view in which the long central portion of the excimer lamp is omitted. It is a longitudinal cross-sectional side view. In addition, the same number is attached | subjected to the structural member which has the function similar to the prior art example shown in FIG.
[0019]
In the present embodiment, an excimer lamp using a rectangular box-shaped discharge vessel 1 that is long in the front-rear direction similar to that shown in FIG. 3 will be described. As shown in FIG. 1 and FIG. 2, the discharge vessel 1 is substantially the same as the cross section of the square tube 1a at the openings at both ends of a long synthetic quartz glass square tube 1a having a horizontally long cross section. It is formed by welding and closing the front and rear end wall plates 1b and 1b made of synthetic quartz glass having the same shape. The square tube 1a is a rectangular tube having a horizontal cross-sectional height of several tens of millimeters and a horizontal width of several tens of millimeters, and the length in the front-rear direction is 1 m or more. Accordingly, the square tube 1a is composed of flat upper and lower wall plates facing each other vertically and flat left and right side wall plates facing each other in the left and right direction. Tip tubes 1c and 1c are projected in advance from the front and rear end wall plates 1b and 1b, which are welded to the openings at both ends of the square tube 1a. Each tip tube 1c is a tube made of synthetic quartz glass that is welded so as to protrude further outward from the outer surface of the front and rear end wall plate 1b, and the inside of the tube is formed in advance at substantially the center of the front and rear end wall plate 1b. It is provided so as to communicate with the opening hole. In the discharge vessel 1, before or after the front and rear end wall plates 1b and 1b are welded to both ends of the square tube 1a, metal thin films of electrodes 2 and 3 are formed on the outer surfaces of the upper and lower wall plates of the square tube 1a. The The electrode 2 is formed so as to cover substantially the entire upper surface of the upper wall plate of the square tube 1a except for the sensor non-coating portion for inspecting the intensity of vacuum ultraviolet rays emitted from the excimer lamp. The electrode 3 is formed in a mesh pattern on almost the entire lower surface of the lower wall plate of the square tube 1a .
[0020]
The discharge vessel 1 produced as described above has one of the tip tubes 1c facing downward to make the discharge vessel 1 stand upright. Inject the suspension. The suspension of the vacuum ultraviolet protective material is obtained by dispersing a fine powder of the vacuum ultraviolet protective material that absorbs or reflects the vacuum ultraviolet light in a liquid for application. Examples of the vacuum ultraviolet protective material for obtaining the action of absorbing vacuum ultraviolet rays include ZnO ₂ and TiO _2, and examples of the vacuum ultraviolet protective material for obtaining the action of reflecting vacuum ultraviolet light include AlO ₃ . In addition to using one or more of those that absorb or reflect vacuum ultraviolet rays, this vacuum ultraviolet protective material may be used by mixing one or more of absorbing and reflecting materials. Good. When the suspension of the vacuum ultraviolet protective material is injected into the lower end of the discharge vessel 1 and discharged again from the same tip tube 1c, the vacuum ultraviolet protective material is applied to the inner surface of the discharge vessel 1, thereby A vacuum ultraviolet protection layer 4 is formed on the inner surface of one end wall plate 1b and the inner surface of one end of the square tube 1a. Further, the discharge vessel 1 is made upright in the opposite direction so that the other tip tube 1c faces downward, and the suspension of the same vacuum ultraviolet protective material is injected and discharged from the tip tube 1c, so that the other end wall plate 1b The vacuum ultraviolet protective layer 4 is also formed on the inner surface and the inner surface of the other end of the square tube 1a. It should be noted that the vacuum ultraviolet ray protection layer 4 formed on the inner surface of the end portion of the square tube 1a is larger than the formation region of these electrodes 2 and 3 so as not to overlap with the electrodes 2 and 3 on the outer surface of the square tube 1a. Furthermore, it is preferable to form only on the end side.
[0021]
The discharge vessel 1 in which the vacuum ultraviolet ray protective layers 4 and 4 are formed as described above discharges air through one tip tube 1c and injects a discharge gas through the other tip tube 1c, so that the inside is discharged. This discharge gas is filled. Even completed by Rie Kishimaranpu to seal the interior of the distal portion of both the tip tube 1c was sealed melt sealing.
[0022]
According to the excimer lamp configured as described above, the inner surfaces of the front and rear end wall plates 1b and 1b disposed at both ends in the front-rear direction of the discharge vessel 1 where the distance of the discharge space is the longest and the intensity of the emitted vacuum ultraviolet rays is the strongest. Then, the vacuum ultraviolet protection layer 4 is formed. When the vacuum ultraviolet protective layer 4 absorbs vacuum ultraviolet rays, most of the vacuum ultraviolet rays radiated in the front-rear direction are absorbed by the vacuum ultraviolet protective layer 4, so that they pass through the front and rear end wall plates 1b and 1b. As a result, only a small amount can be suppressed, and deterioration can be suppressed. Even when the vacuum ultraviolet protective layer 4 reflects vacuum ultraviolet rays, most of the vacuum ultraviolet rays radiated in the front-rear direction are reflected by the vacuum ultraviolet protective layer 4. Deterioration can be suppressed because only a small amount passes through 1b and 1b. For this reason, the front and rear end wall plates 1b and 1b disposed at both ends in the longitudinal direction of the discharge vessel 1 are synthesized by receiving much stronger vacuum ultraviolet rays than the upper and lower wall plates and left and right side wall plates of the square tube 1a. It is possible to prevent the deterioration of the quartz glass from rapidly progressing and shortening the life of the excimer lamp. Moreover, since this vacuum ultraviolet protective layer 4 is formed at both ends in the front-rear direction of the square tube 1a, the synthetic quartz glass at these ends that receives strong vacuum ultraviolet rays in accordance with the front and rear end wall plates 1b and 1b. Deterioration can also be prevented.
[0023]
In the discharge vessel 1, tip tubes 1c and 1c are welded to front and rear end wall plates 1b and 1b arranged at both ends in the front and rear direction, and the tips of these tip tubes 1c and 1c are melt-sealed. Up to this point, the opening is electrically connected to the inside, so that it is used for filling and discharging the suspension for forming the vacuum ultraviolet ray protective layer 4 in addition to filling the discharge gas through the tip tubes 1c and 1c. Will be able to. Moreover, these tip tubes 1c and 1c are provided on the front and rear end wall plates 1b and 1b different from the upper and lower wall plates of the square tube 1a on which the electrodes 2 and 3 are formed. There is no such thing as blocking the downward irradiation.
[0024]
In the above embodiment, the case where the vacuum ultraviolet protective layers 4 are provided only on the inner surfaces of the front and rear end wall plates 1b and 1b and the square tube 1a of the discharge vessel 1 has been described. Similarly, the vacuum ultraviolet protection layer 4 may be formed on the inner surface of the substrate. These left and right side wall plates also receive a relatively strong vacuum ultraviolet ray in the left and right direction that is several times longer than the vertical direction, so there is a risk that the synthetic quartz glass will deteriorate earlier than the upper and lower wall plates. If the vacuum ultraviolet protective layer 4 similar to the inner surfaces of the front and rear end wall plates 1b and 1b is formed, this deterioration can be prevented.
[0025]
In the case where the vacuum ultraviolet protective layer 4 is also formed on the inner surfaces of the left and right side wall plates as described above, after the discharge vessel 1 is erected and the suspension of the vacuum ultraviolet protective material is injected from the lower tip tube 1c, the discharge vessel 1 Is slowly rotated around an axis orthogonal to the surface on which the electrodes 2 and 3 are formed, the suspension moves from the inner surface of one end wall plate 1b to the inner surface of one side wall plate, and the other Since it moves from the inner surface of the end wall plate 1b to the inner surface of the other side wall plate, the vacuum ultraviolet ray protection layer 4 can be formed on the inner surfaces of all these wall plates. Further, when the vacuum ultraviolet protective layer 4 is also formed on the inner surfaces of the left and right side wall plates, the tip tubes 1c and 1c can be provided on the left and right side wall plates. Moreover, if the charging efficiency of the discharge gas is sacrificed to some extent, the tip tube 1c can be provided only on one of the front and rear end wall plates 1b and 1b and the left and right side wall plates.
[0026]
In the above embodiment, the case where the tip tube 1c is used to form an opening communicating with the inside of the discharge vessel 1 has been described. However, another tube material may be attached or a simple opening hole may be formed. Such an opening formed by the tip tube 1c or the like can be provided in the discharge vessel 1 in which the vacuum ultraviolet ray protective layer 4 is not formed for filling the discharge gas. At this time, it is provided on at least other wall plates excluding the wall plate perpendicular to the direction of irradiation of vacuum ultraviolet rays so as not to hinder the irradiation of vacuum ultraviolet rays.
[0027]
Moreover, in the said embodiment, although the case where the vacuum ultraviolet-ray protective layer 4 was formed in the inner surface of the wall board of the discharge vessel 1 was shown, the material of the synthetic quartz glass of a part of each wall board of this discharge vessel 1 is made into vacuum. The wall plate can be prevented from deteriorating by changing to one having a low ultraviolet transmittance or a high reflectance. That is, at least the front and rear end wall plates 1b and 1b of the discharge vessel 1 are replaced with one having a lower transmittance of vacuum ultraviolet light than a lower wall plate through which vacuum ultraviolet light for original irradiation is transmitted. Change to one with higher reflectivity. Examples of materials having low transmittance of vacuum ultraviolet rays include fused quartz and ozone-free quartz in which titanium or vanadium compounds are added to natural quartz glass. Moreover, as a thing with a high reflectance of a vacuum ultraviolet ray, there exists a thing etc. which scattered the vacuum ultraviolet ray, for example by processing the surface of synthetic quartz glass in the shape of a glass, and raised the reflectance. Furthermore, the thing with the low transmittance | permeability of vacuum ultraviolet rays and a high reflectance can also be used. When the front and rear end wall plates 1b and 1b have a high absorption rate of vacuum ultraviolet rays, most of the vacuum ultraviolet rays radiated in the front and rear direction are absorbed by the surface layer portion of the inner surface of each front and rear end wall plate 1b. Only a small amount of light completely passes through the front and rear end wall plates 1b and only the surface layer portion deteriorates, but most other deterioration can be suppressed. Even when the front and rear end wall plates 1b and 1b have high vacuum ultraviolet reflectivity, most of the vacuum ultraviolet rays radiated in the front and rear direction are reflected by the front and rear end wall plates 1b. Only a small amount permeates the wall plate 1b, and deterioration can be suppressed. Furthermore, not only the front and rear end wall plates 1b and 1b, but also both end portions and the left and right side wall plates of the square tube 1a can be changed to those having a high vacuum ultraviolet ray absorption rate and reflectivity.
[0028]
Moreover, in the said embodiment, although the case where the discharge vessel 1 was produced by welding the front-and-back end wall plates 1b and 1b to the both-ends opening part of the square tube 1a was shown, the production methods of this discharge vessel 1 are arbitrary. . For example, a long cylindrical tube made of synthetic quartz glass is molded so that the cross section is a horizontally long square, and the front and rear end wall plates 1b and 1b may be welded to both end openings. It can also be produced by melting and sealing both ends of a cylindrical tube. Since the discharge vessel 1 produced in this way only needs to have flat and substantially parallel wide regions of the upper and lower wall plates forming the electrodes 2 and 3, for example, the left and right side wall plates when a cylindrical tube is formed are semicylindrical. For example, the melted and sealed front and rear end wall plates may be curved by melting. Alternatively, the discharge vessel 1 can be produced by welding six sheets of synthetic quartz glass. In this case, since each wall board is comprised with a different board | plate material, it becomes possible easily to change arbitrary wall boards into a thing with a high absorption factor and reflectance of a vacuum ultraviolet ray.
[0029]
Moreover, in the said embodiment, although the case where all the wall boards of the discharge vessel 1 were comprised with synthetic quartz glass was shown, other wall boards except the wall board which permeate | transmits the vacuum ultraviolet rays for original irradiation are appropriate. If it is a dielectric material, it is not necessarily required to be synthetic quartz glass. Further, in the above embodiment, an excimer lamp that emits vacuum ultraviolet light having a wavelength of 172 nm has been described. Therefore, a case where synthetic quartz glass having a high transmittance of vacuum ultraviolet light having this wavelength is used has been described, but vacuum ultraviolet light used by the excimer lamp is shown. An appropriate dielectric material can be used in accordance with the wavelength.
[0030]
【The invention's effect】
As apparent from the above description, according to the excimer lamp of the present invention, and front and rear end wall plate at both ends intensity of the strongest longitudinal direction of the vacuum ultraviolet rays emitted, the intensity of the vacuum ultraviolet rays than the vertical By preventing deterioration of the left and right side wall plates in the left and right direction, which is strengthened, it is possible to prevent the life from being shortened.
[Brief description of the drawings]
FIG. 1 is a perspective view showing an embodiment of the present invention and omitting a long central portion of an excimer lamp.
FIG. 2 shows an embodiment of the present invention, and is a longitudinal sectional side view in which a long central portion of an excimer lamp is omitted.
FIG. 3 is a perspective view showing a conventional example and omitting a long central portion of an excimer lamp.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Discharge vessel 1a Square tube 1b Front and rear end wall plate 1c Tip tube 2 Electrode 3 Electrode 4 Vacuum ultraviolet protective layer

Claims (2)

It is a sealed container made of a dielectric material that has a longest front and back, a shortest top and bottom, and substantially flat top and bottom wall plates facing each other in a substantially parallel shape and transmitting vacuum ultraviolet rays. In an excimer lamp comprising a discharge vessel filled with a discharge gas for excimer emission and electrodes formed on the outer surfaces of the upper and lower wall plates of the discharge vessel and irradiating vacuum ultraviolet rays downward through the lower wall plate ,
An excimer lamp characterized in that a vacuum ultraviolet ray protection layer is formed on the inner surface of at least the front and rear end wall plates at both front and rear ends of the discharge vessel.   The longest front and back, the top and bottom are the shortest, and the substantially flat top and bottom wall plates facing each other at the top and bottom have a substantially parallel shape to each other, at least the lower wall plate transmits vacuum ultraviolet rays, and at least the front and rear ends of both front and rear ends The wall plate is a hermetically sealed container made of a dielectric material having a higher vacuum ultraviolet reflectivity than the lower wall plate, and includes a discharge vessel in which a discharge gas for excimer emission is enclosed, and upper and lower sides of the discharge vessel. An excimer lamp comprising an electrode formed on an outer surface of a wall plate and irradiating vacuum ultraviolet rays downward through the lower wall plate.

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