JP2854255B2 - Dielectric barrier discharge lamp device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to, for example, a kind of ultraviolet light source device for photochemical reaction, in which excimer molecules are formed by dielectric barrier discharge, and a so-called dielectric barrier utilizing light emitted from the excimer molecules. The present invention relates to an improvement in a dielectric barrier discharge lamp device using a discharge lamp, for example, a dry cleaning device for a silicon wafer.

[0002]

2. Description of the Related Art As a technique related to the present invention, there is, for example, Japanese Patent Application Laid-Open No. 4-301357.
There, a discharge vessel is filled with a discharge gas for forming excimer molecules, and a dielectric barrier discharge (also known as an ozonizer discharge or a silent discharge) is issued. (See page 263)
A lamp using light emitted from the excimer molecule, i.e., a dielectric barrier discharge lamp, wherein the discharge vessel is cylindrical and at least a part of the discharge vessel is A cylindrical dielectric barrier discharge lamp is described, which also serves as a dielectric for a dielectric barrier discharge, the dielectric being light transmissive, and a metal mesh electrode provided on at least a part of the dielectric. It also describes a dielectric barrier discharge lamp device in which a plurality of the cylindrical dielectric barrier discharge lamps are arranged in parallel.

[0003] An outline of a general dielectric barrier discharge will be described below with reference to FIG. 5 which is a schematic view of a cylindrical dielectric barrier discharge lamp. The discharge vessel 1 is made of glass as a dielectric, and has a hollow cylindrical shape in which an inner tube 2 and an outer tube 3 are coaxially arranged. An outer electrode 4 for light-transmitting dielectric barrier discharge is provided on the outer surface of the outer tube 3, and an inner electrode 5 for dielectric barrier discharge serving also as a light reflection film formed by vapor deposition of aluminum is provided on the outer surface of the inner tube 2. Are provided respectively. At one end of the discharge vessel 1, a getter chamber 6 for accommodating a getter 7 is provided. Getter 7 is discharge space 8
Has a function of removing impurity gases (for example, H ₂ O, etc.) and stabilizing discharge. A discharge space 8 is formed between the inner surface of the outer tube 3 facing the electrode 4 and the inner surface of the inner tube 2 facing the electrode 5. The discharge space 8 is filled with a discharge gas for forming excimer molecules by dielectric barrier discharge,
When a voltage is applied to the electrodes 4 and 5 by the AC power supply 10,
Dielectric barrier discharge is stably generated in the discharge space 8, and excimer light is emitted.

[0004]

The cylindrical dielectric barrier discharge lamp as described above is useful because it has various features not found in conventional low-pressure glow discharge lamps and arc discharge lamps. In particular, when the discharge vessel is formed into a substantially cylindrical shape and an inner electrode is provided substantially coaxially with the discharge vessel inside the discharge vessel, a commercially available glass tube, ceramic tube, or the like can be used, and the structure can be reduced. Therefore, there is an advantage that the manufacture is easy, and therefore, a cylindrical dielectric barrier discharge lamp can be provided at low cost. Therefore, a dielectric barrier discharge lamp device in which a plurality of the cylindrical dielectric barrier discharge lamps are arranged in parallel to form a substantially planar light source,
There is an advantage that a flat light source can be obtained at low cost.

[0005] However, the present inventors have experimentally confirmed that a dielectric barrier discharge lamp device using a conventional cylindrical dielectric barrier discharge lamp using a metal mesh electrode has the following disadvantages. discovered. That is, in a dielectric barrier discharge lamp device in which a plurality of cylindrical dielectric barrier discharge lamps each using a metal mesh electrode are arranged in parallel, radiation on the light extraction window surface at an intermediate portion between adjacent dielectric barrier discharge lamps. The illuminance was found to be significantly lower than the expected value obtained by superimposing the light distribution measurements of one of the dielectric barrier discharge lamps on adjacent lamps.
Further, as the lighting time elapses, the irradiance decreases due to deterioration of the transmittance of the discharge vessel glass, and the rate of decrease in the irradiance depends on the cylindrical dielectric barrier discharge lamp. In comparison with the area immediately below (front), the difference was remarkable immediately below (front) the middle part of the adjacent dielectric barrier discharge lamp. That is, there is a disadvantage that the irradiance distribution becomes uneven as the lighting time elapses. The above-mentioned disadvantages were particularly significant in a dielectric barrier discharge lamp device using a dielectric barrier discharge lamp having a center wavelength of excimer light of 200 nm or less.

The above causes are considered to be as follows. That is, when the cylindrical dielectric barrier discharge lamps are arranged in parallel, part of the excimer light emitted from the dielectric barrier discharge lamp is absorbed by the metal mesh electrode of the adjacent cylindrical dielectric barrier discharge lamp. The first cause. Although the above-mentioned disadvantages could be improved to some extent by improving the reflectance of the metal mesh electrode, a part of the reflected excimer light was subjected to multiple reflections at the metal mesh electrode, or the glass serving as the discharge vessel was changed. Due to transmission many times, it was impossible to largely eliminate it.

[0007] The second cause seems to be as follows. As the lighting time elapses, the surface of the metal mesh electrode is oxidized or contaminated. Dust accumulates in the mesh of the metal mesh electrode. These contaminations reduce the substantial transmittance of the discharge vessel and reduce the light output. The irradiance immediately below the cylindrical dielectric barrier discharge lamp decreases almost in proportion to the decrease in the light output, whereas the irradiance immediately below the middle part of the adjacent dielectric barrier discharge lamp is the adjacent dielectric barrier discharge lamp. Because the contribution of the reflected light from the barrier discharge lamp is large,
It appears that the irradiance is significantly lower than the substantial reduction in the transmittance of the discharge vessel.

The above-mentioned disadvantage is a phenomenon peculiar to a dielectric barrier discharge lamp device in which cylindrical dielectric barrier discharge lamps having metal mesh electrodes are arranged in parallel.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object thereof is to provide a light-transmitting discharge vessel having at least a substantially cylindrical outer shape and at least an outer surface of the discharge vessel. A metal mesh electrode provided on a part of the entire circumference, an inner electrode provided substantially coaxially with the discharge vessel inside the metal mesh electrode, and an excimer molecule is formed in the discharge vessel by dielectric barrier discharge. A cylindrical dielectric barrier discharge lamp comprising a discharge gas to be discharged, and a plurality of the cylindrical dielectric barrier discharge lamps arranged and housed in parallel, and a light extraction window for extracting excimer light emitted from the excimer molecules. And a dielectric barrier discharge lamp device provided with a power supply for performing a dielectric barrier discharge, wherein the irradiance immediately below the adjacent cylindrical dielectric barrier discharge lamp is sufficient. Ku, and high efficiency elapsed to take in the illuminance distribution of the lighting time is not uneven, is to provide a highly reliable dielectric barrier discharge lamp device.

[0010]

In order to solve the above-mentioned problems, the invention according to claim 1 of the present invention is directed to a light-transmitting discharge vessel having at least a substantially cylindrical outer shape, and at least one of the outer surfaces of the discharge vessel. A metal mesh electrode provided on the entire circumference of the portion, an inner electrode provided substantially coaxially with the discharge vessel inside the metal mesh electrode, and filled in the discharge vessel to form excimer molecules by dielectric barrier discharge. It has a cylindrical dielectric barrier discharge lamp composed of a discharge gas, and a plurality of cylindrical dielectric barrier discharge lamps arranged and housed in parallel, and a light extraction window for extracting excimer light emitted from the excimer molecules. In a lamp house and a dielectric barrier discharge lamp device provided with a power supply for performing a dielectric barrier discharge,
Approximately V between adjacent cylindrical dielectric barrier discharge lamps
A cylindrical light-reflecting plate provided adjacent to said cylindrical dielectric
The distance X between the central axes of the barrier discharge lamps is
It is configured to be 3.5 times or less the diameter D of the barrier discharge lamp.
It is.

[0011]

[0012] The invention of claim 2 of the present invention is the originating <br/> light of claim 1, the common tangent of the circumference of the cylindrical dielectric barrier discharge lamp adjacent that face the light extraction window The reference range L is set at 25 degrees of the diameter of the cylindrical dielectric barrier discharge lamp in a direction perpendicular to both the tangent and the tube axis of the cylindrical dielectric barrier discharge lamp and away from the light extraction window.
% Of the length of the V-shaped light reflecting plate is within the range of L when the length is in the range of%.

[0013]

According to the first aspect of the present invention, there is provided a light-transmissive discharge vessel having at least a substantially cylindrical outer shape, and a metal mesh electrode provided on at least a part of an outer surface of the discharge vessel. A cylindrical dielectric barrier discharge lamp comprising an inner electrode provided substantially coaxially with the discharge vessel inside the metal mesh electrode, and a discharge gas filled in the discharge vessel and forming excimer molecules by dielectric barrier discharge. And a lamp house having a plurality of cylindrical dielectric barrier discharge lamps arranged in parallel and housed therein, and a light extraction window for extracting excimer light emitted from the excimer molecules, and for performing a dielectric barrier discharge. In the dielectric barrier discharge lamp device provided with a power source, a substantially V-shaped light reflecting plate is provided between the adjacent cylindrical dielectric barrier discharge lamps. Released from A discharge lamp, excimer light toward the adjacent dielectric barrier discharge lamp,
Since the light is reflected by the substantially V-shaped light reflecting plate and travels toward the light extraction window, the light does not directly enter the adjacent dielectric barrier discharge lamp and is absorbed by the metal mesh electrode. The irradiance immediately below the dielectric barrier discharge lamps becomes sufficiently high, and a highly efficient dielectric barrier discharge lamp device can be obtained.

Further, in the first aspect of the present invention,
Is the distance X between the central axes of adjacent cylindrical dielectric barrier discharge lamps, and the diameter D of the cylindrical dielectric barrier discharge lamp.
Since it is configured to be 3.5 times or less, the amount of excimer light incident on the light extraction window increases, and in addition to the above-described effects, a dielectric barrier discharge lamp device with high irradiance can be obtained. When the substantially V-shaped light reflecting plate is not provided, the distance X between the central axes of the adjacent cylindrical dielectric barrier discharge lamps is 3.5 times the diameter D of the cylindrical dielectric barrier discharge lamp. In the following configuration, the absorption of excimer light by the metal mesh electrode of the adjacent dielectric barrier discharge lamp becomes remarkably large, and as a result, the light extraction efficiency decreases and the irradiance distribution becomes uneven with the elapse of the lighting time. The disadvantage of the occurrence of the expansion becomes significantly large. Incidentally, the outer diameter D of the cylindrical dielectric barrier discharge lamp in the present invention is an outer diameter including the thickness of the mesh electrode measured in a state of being mounted on the discharge vessel. For example, when a cylindrical mesh in which wires having a diameter of dmm intersect is mounted on a discharge vessel having a diameter of Zmm, the outer diameter D of the lamp including the thickness of the conductive mesh electrode is determined when the wire " The sum of Z and four times d is obtained in the relationship of "overlap due to twisting".

[0015] In the invention of claim 2 of the present invention, wherein
Item 1. In the invention according to Item 1, a range L of a circumference of the cylindrical dielectric barrier discharge lamp adjacent to the light extraction window, which is based on a common tangent line facing the light extraction window, is defined as: The V-shaped light reflecting plate, which is perpendicular to both of the tube axes of the cylindrical dielectric barrier discharge lamp and is 25% of the diameter of the cylindrical dielectric barrier discharge lamp in a direction away from the light extraction window; Are arranged within the range of L, so that the effect of the invention of claim 1 is more remarkably exhibited. Note that, even if the apex of the V-shaped light reflection plate extends beyond the tangent to the side of the light extraction window, excimer light emitted from the dielectric barrier discharge lamp is adjacent to the cylindrical dielectric barrier discharge. The effect of preventing the light from being incident on the lamp is not increased, but rather, a drawback occurs in that the efficiency of extracting the excimer light is reduced. Further, when the apex of the V-shaped light reflector is located at a position farther from the light extraction window than the range L, the excimer light emitted from the dielectric barrier discharge lamp is adjacent to the cylindrical dielectric reflector. The effect of preventing light from entering the body barrier discharge lamp is not sufficient,
The effect of improving light extraction efficiency was reduced.

[0016]

1 is a schematic view of a dielectric barrier discharge lamp device according to a first embodiment of the present invention. FIG. 1 is an explanatory diagram showing a cross section of a cylindrical dielectric barrier discharge lamp viewed from the tube axis direction. The cylindrical dielectric barrier discharge lamps 1a, 1b, and 1c in this embodiment have the same configuration as the lamp of FIG. 5, and the discharge vessel 1 is made of synthetic quartz glass having a total length of about 250 mm, and has an outer diameter of 16 mm and a wall thickness of 1 mm. An inner tube 2 and an outer tube 3 having an outer diameter of about 26.5 mm and a wall thickness of 1 mm are coaxially arranged to form a hollow cylinder. The outer tube 3 also serves as a dielectric barrier of the dielectric barrier discharge and a light extraction window member, and has an outer electrode 4 made of a metal mesh transmitting light on its outer surface.
Is provided. The length of the metal net in the pipe axis direction is 200
mm. The reticulated electrode 4 is a cylindrical net formed by seamlessly knitting a Monel wire having a diameter of 0.15 mm and having elasticity in the axial direction. The discharge vessel 1 is inserted into the cylindrical metal net and pulled in the axial direction of the lamp. As a result, a reticulated electrode 4 closely formed outside the outer tube 3 is formed. Accordingly, the outer diameter D of the cylindrical dielectric barrier discharge lamp is about 27.1 mm. Further, on the outer surface of the inner tube 2, there is provided an inner electrode 5 for dielectric barrier discharge which also serves as a light reflection film formed by vapor deposition of aluminum. At one end of the discharge vessel 1, a getter accommodating chamber 6 is provided by extending the tube wall of the discharge vessel 1. A barium getter 7 made of a barium alloy was stored in the getter storage chamber 6, and the barium getter 7 was heated at a high frequency to form a barium thin film in the getter storage chamber. The discharge space 8 was filled with a 30 kPa xenon gas as a discharge gas.

The above-mentioned cylindrical dielectric barrier discharge lamp 1
a, 1b, and 1c were housed in the lamp house 21. An airtight lamp house 21 is formed by a cooling block 22 serving both as a lamp cooling and light reflecting plate, a rectangular light extraction window 20 made of synthetic quartz glass having an opening of 170 mm × 170 mm, and a side plate 23. ing. The cooling block 22 is provided with cooling fluid passages 28 and 29. The cylindrical dielectric barrier discharge lamps 1a and 1b, 1
The distance X between the central axes of b and 1c is 60 mm. Therefore, the ratio of the distance X between the central axes of adjacent cylindrical dielectric barrier discharge lamps to the outer diameter D of the cylindrical dielectric barrier discharge lamp is about 2.2.

The cylindrical dielectric barrier discharge lamps 1a and 1
b, a V-shaped light reflecting plate 11, 1 having a length of 170 mm formed by bending an aluminum plate between 1b and 1c.
3 were provided. The vertices 12 of the V-shaped light reflecting plates 11 and 13;
14 is located on the common tangent line PQR of the circumference of the cylindrical dielectric barrier discharge lamps 1a, 1b, 1c facing the light extraction window 20. A space 26 between the cylindrical dielectric barrier discharge lamps 1a, 1b, 1c and the rectangular light extraction window 20 is filled with nitrogen gas injected from an inert gas inlet 24. 25 is a gas outlet. Around the rectangular light extraction window 20, the size of the opening is 17
A light reflecting plate 27 made of a hollow prismatic aluminum plate having a size of 0 mm × 170 mm and a height of 15 mm was provided.

The cylindrical dielectric barrier discharge lamps 1a, 1
b and 1c were connected to one power supply 10 in parallel. When the output of the power supply is about 13 kHz and the applied voltage to the lamp is about 12 kV expressed by the voltage between the maximum value and the minimum value, the dielectric barrier discharge lamps 1a, 1b and 1c are lit at about 50W each. And a wavelength 160 having a maximum value at a wavelength of 172 nm emitted from an excimer molecule of xenon.
Vacuum ultraviolet rays having a wavelength in the range of 180 nm to 180 nm were emitted. The portion of the vacuum ultraviolet light directed toward the adjacent dielectric barrier discharge lamp is reflected by the V-shaped light reflecting plates 11 and 13, turned to the light extraction window 20, and emitted from the light extraction window 20. That is, the extraction efficiency of the vacuum ultraviolet light was increased. In this case, as described above, since the space 26 between the cylindrical dielectric barrier discharge lamps 1a, 1b, 1c and the light extraction window 20 is filled with nitrogen gas, the vacuum ultraviolet rays are not absorbed by the space 26. . Therefore, from the rectangular light extraction window 20, the sum of the vacuum ultraviolet rays emitted from the cylindrical dielectric barrier discharge lamps 1a, 1b, 1c is emitted. Therefore, the rectangular light extraction window 20 is substantially formed. It becomes a rectangular vacuum ultraviolet light source.

A glass of 150 mm × 150 mm was placed in the air at a distance of about 3 mm from the light extraction window 20 of the above-described dielectric barrier discharge lamp device, and vacuum ultraviolet rays were irradiated by the dielectric barrier discharge lamp device. Uniform irradiance was obtained, and as a result, organic contaminants on the glass could be uniformly oxidized and removed in a state where the material other than the glass to be processed was not irradiated with the vacuum ultraviolet rays.

FIG. 2 shows a second embodiment of the present invention. In this embodiment, a cylindrical dielectric barrier discharge lamp 1a, 1
b, 1c and the configuration of the light extraction window 20 are the same as those of the first embodiment of the present invention, and the distance X between the central axes of the cylindrical dielectric barrier discharge lamps 1a and 1b, 1b and 1c is 60 mm.
It is. Thus, the ratio of the distance X between the central axes of adjacent cylindrical dielectric barrier discharge lamps to the diameter D of the cylindrical dielectric barrier discharge lamp is about 2.2. The V-shaped light reflection plates 31 and 33 also serve as a part of the wall of the lamp house 21 and are formed by bending a single aluminum plate. Also, the vertices 3 of the V-shaped light reflecting plates 31 and 33
The position Y of 2, 34 is 5 mm above the common tangent line PQR, and exists in L, which is a range in which the apex of the V-shaped light reflecting plate is allowed to exist. Note that L in this embodiment
Is 6.77 mm. This embodiment has, in addition to the advantages of the first embodiment, an advantage that the structure is simple, lightweight, and can be manufactured at low cost.

The third embodiment of the present invention is different from the first embodiment in that a V-shaped light reflecting plate is used instead of the V-shaped light reflecting plate, and the light on the trapezoid shown in FIG. 3 is slightly flattened. This uses a reflection plate. In this embodiment, in addition to the advantage of the first embodiment, there is an advantage that processing of the light reflecting plate is simple.

The fourth embodiment of the present invention is different from the first embodiment in that, instead of the V-shaped light reflecting plate, a bullet-shaped light shown in FIG. This uses a reflection plate. In this embodiment, in addition to the advantage of the first embodiment, there is an advantage that irradiance can be made more uniform.

[0024]

As described above, according to the present invention,
The following effects can be obtained. In the invention of claim 1 of the present invention, at least a light-transmissive discharge vessel having a substantially cylindrical outer shape, a metal mesh electrode provided on at least a part of an outer surface of the discharge vessel, and a metal mesh electrode An inner electrode provided substantially coaxially with the discharge vessel inside the electrode, a cylindrical dielectric barrier discharge lamp formed of a discharge gas filled in the discharge vessel and forming excimer molecules by dielectric barrier discharge, It comprises a lamp house having a light extraction window for taking out the excimer light emitted from the excimer molecules, in which the cylindrical dielectric barrier discharge lamps are arranged and housed in parallel, and a power supply for performing a dielectric barrier discharge. and the dielectric barrier discharge lamp device, adjacent the cylindrical induction
An approximately V-shaped light reflector is installed between the electrical barrier discharge lamps.
And adjacent cylindrical dielectric barrier discharge lamp
Distance between the central axes of the cylindrical dielectric barrier discharge lamp
Is 3.5 times or less the diameter D of
Rate is high and a uniform irradiation surface can be obtained.
Provide a dielectric barrier discharge lamp device that can obtain irradiance
it can.

[0025]

In the invention of claim 2 of the present invention,
Item 1. In the invention according to Item 1, a range L based on a common tangent of the circumference of the adjacent cylindrical dielectric barrier discharge lamp facing the light extraction window is defined as the range L between the tangent and the cylindrical dielectric barrier discharge lamp. The apex of the V-shaped light reflecting plate is L at right angles to both of the tube axes and in a direction away from the light extraction window within a range of 25% of the diameter of the cylindrical dielectric barrier discharge lamp. , The dielectric barrier discharge lamp device can further provide the advantages of the first or second aspect of the present invention.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of an embodiment of a dielectric barrier discharge lamp device of the present invention.

FIG. 2 is an explanatory view of another embodiment of the dielectric barrier discharge lamp device of the present invention.

FIG. 3 is an explanatory view of a main part of another embodiment of the dielectric barrier discharge lamp device of the present invention.

FIG. 4 is an explanatory view of a main part of another embodiment of the dielectric barrier discharge lamp device of the present invention.

FIG. 5 is an explanatory diagram of a cylindrical dielectric barrier discharge lamp.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Discharge container 1a, 1b, 1c Dielectric barrier discharge lamp 2 Inner tube 3 Outer tube 4 Reticulated electrode 5 Inner electrode 6 Getter accommodating chamber 7 Getter 11,13 V-shaped light reflector 12,14 V-shaped light reflector Vertex 20 Light extraction window 21 Lamp house 22 Cooling block 27 Light reflector

──────────────────────────────────────────────────の Continuation of the front page Examiner Hiroshi Ogawa (56) References JP-A-4-229671 (JP, A) JP-A-3-174243 (JP, A) JP-A-2-75339 (JP, A) 54-33445 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) H01J 65/00 G21K 5/00

Claims (2)

(57) [Claims] 1. A light-transmitting discharge vessel having a substantially cylindrical outer shape, a metal mesh electrode provided on at least a part of an outer surface of the discharge vessel, and a discharge vessel provided inside the metal mesh electrode. An inner electrode provided substantially coaxially with a cylindrical dielectric barrier discharge lamp formed of a discharge gas filled in the discharge vessel and forming excimer molecules by dielectric barrier discharge, and a plurality of the cylindrical dielectrics A lamp house having a light extraction window for storing barrier discharge lamps arranged in parallel and extracting excimer light emitted from the excimer molecules;
In a dielectric barrier discharge lamp device provided with a power supply for performing a dielectric barrier discharge, a voltage of approximately V between adjacent cylindrical dielectric barrier discharge lamps.
A cylindrical light-reflecting plate provided adjacent to said cylindrical dielectric
The distance X between the central axes of the barrier discharge lamps is
Be configured to be 3.5 times or less the diameter D of the barrier discharge lamp
A dielectric barrier discharge lamp device characterized by the above-mentioned. 2. A range L based on a common tangent line of the circumference of the cylindrical dielectric barrier discharge lamp adjacent to the light extraction window, which is defined by the tangent line and the tube of the cylindrical dielectric barrier discharge lamp. At right angles to both axes and away from the light extraction window, the diameter of the cylindrical dielectric barrier discharge lamp is 2 mm.
2. The dielectric barrier discharge lamp device according to claim 1, wherein when the length is within a range of 5%, the apex of the V-shaped light reflection plate is present within the range of L.