WO2011078181A1

WO2011078181A1 - Dielectric barrier discharge lamp and ultraviolet irradiation device using the same

Info

Publication number: WO2011078181A1
Application number: PCT/JP2010/073028
Authority: WO
Inventors: 和也畑瀬; 毅片桐; 佳憲金森; 弘実坂元
Original assignee: 株式会社Ｇｓユアサ
Priority date: 2009-12-22
Filing date: 2010-12-21
Publication date: 2011-06-30
Also published as: KR101389786B1; KR20120042920A; JPWO2011078181A1; TW201140647A; TWI480921B; CN102473586A

Abstract

In order to reduce the deposition and solidification of debris flying into the discharge tube, a semi-open dielectric barrier discharge lamp for generating vacuum ultraviolet radiation is provided with a discharge tube (1) which internally seals a discharge gas for the generation of excimer radiation and irradiates the vacuum ultraviolet radiation downwards via a bottom wall plate not provided with a front glass but having a flat surface, and electrodes (2, 3) disposed inside said discharge tube. The sidewalls located on the long side surfaces surrounding the bottom wall plate in the discharge tube are configured from a light shielding member (4a) which shields at least 50% of ultraviolet rays.

Description

Dielectric barrier discharge lamp and ultraviolet irradiation apparatus using the same

The present invention relates to a dielectric barrier discharge lamp for irradiating vacuum ultraviolet rays, and more particularly to a dielectric barrier discharge lamp having a flat discharge tube shape on the irradiation side and a semi-open type ultraviolet irradiation apparatus using the same.

In recent years, dielectric barrier discharge lamps having a discharge tube with a flat surface on the irradiation side are known (

Patent Documents

1, 2, 3, etc.). The feature is that the in-plane uniformity of the irradiation light is good, and it is not necessary to provide an expensive front glass (corresponding to the window portion 102 in Patent Document 2 and FIG. 8) between the discharge tube and the irradiation object. Therefore, an ultraviolet irradiation device can be manufactured at low cost by connecting to a predetermined power supply device, and there is an advantage that vacuum ultraviolet rays can be directly irradiated to an irradiation object (Patent Document 3). Such a type that does not have a front glass and can directly irradiate an irradiation object with vacuum ultraviolet rays is called a semi-open type ultraviolet irradiation device. Since this type of dielectric barrier discharge lamp does not have a front glass, various scattered matters are likely to adhere to the discharge tube due to the airflow in the lamp house that houses the discharge tube, and crystallization (solidification) that adheres to the tube wall There is a problem that the discharge tube is damaged by the deposited matter (hereinafter referred to as “solidified deposit” or “white powder”). Deposits adhered to the outer wall of the discharge tube can be periodically wiped away, but cannot be removed after solidifying to some extent after being exposed to ultraviolet rays for a long time.

It is thought that the adhering of the flying material flying to the discharge tube is an “organosilicon compound” such as organic HMDS (hexamethylene disilazane). The white powder adhering to the discharge tube is generated because the organosilicon compound is decomposed into a siloxane precursor by ultraviolet light from the discharge tube and deposited on the outer peripheral surface of the discharge tube, and the white powder is oxidized and dehydrated by light and heat. It is inferred that the polymerization reaction proceeds and a strong glassy adhesion film is formed. The adhesion of white powder causes the performance of the discharge tube to deteriorate significantly. Moreover, if the white powder adhering to the discharge tube falls off by nitrogen gas or the like flowing from the back surface or the side surface of the discharge tube in the irradiation device, the discharge tube can also be a source of contamination of the workpiece (object to be irradiated).

Patent Document 1 discloses that a “vacuum ultraviolet protection layer” is formed on the inner surfaces of front and rear end wall plates and left and right side wall plates in a discharge vessel of a dielectric barrier discharge lamp formed in a very long shape on the front and rear sides. It discloses that deterioration of the wallboard can be suppressed (paragraphs 10 to 11). This vacuum ultraviolet protective layer is composed of at least absorbing or reflecting vacuum ultraviolet (the 20th paragraph, etc.).

JP 2004-127710 A WO2007 / 013602 JP 2009-183949 A

The present inventors examined the relationship between the film thickness of the solidified deposit and the ultraviolet light shielding rate, and found that the film thickness significantly decreased when the light shielding rate was above a certain value. First, a method for measuring the thickness of the solidified deposit will be described. FIG. 11 is a schematic diagram of a measuring apparatus. The measuring device 60 includes a surface plate 62, a discharge tube fixing base 63, a micrometer fixing base 64, and a micrometer 65. The measuring device 60 fixes the discharge tube fixing base 63 and the micrometer fixing base 64 to the surface plate 62, the micrometer 65 to the micrometer fixing base 64, and the discharge tube 61 to the discharge tube fixing base 63, respectively. The measurement position is not misaligned. A micrometer 65 manufactured by MITUTOYO (model name: M810-50) was used. The film thickness of the solidified deposit is measured by using the measuring device 60, first measuring the width of the discharge tube 61 before lighting without deposits, and then lighting the discharge tube 61 with an average illuminance of 100 mW / cm ^2. The width of the discharge tube 61 was measured after a predetermined time (10 hours, 100 hours, 1000 hours), and finally, the difference between the width before lighting of the discharge tube 61 and the width after lighting was obtained. FIG. 6 is a graph showing the relationship of the film thickness of the solidified deposit with respect to the ultraviolet light shielding rate. The horizontal axis represents the ultraviolet light shielding rate, and the vertical axis represents the film thickness [μm] of the solidified deposit when solidified (vitrified) when the light shielding rate is changed from 0 to 100%. Here, the irradiation time of 1000 hours is a sufficient time that solidification is considered to be saturated. Comparing the three graphs of irradiation time of 10 hours, 100 hours, and 1000 hours, it can be seen that the film thickness of the solidified deposit is drastically reduced when the ultraviolet light shielding rate is increased to some extent.

In other words, the most effective method for reducing the adhesion and solidification of flying objects flying on the discharge tube is to shield the discharge tube from solidification as much as possible even if it adheres to the discharge tube. Find knowledge. According to this knowledge, for example, alumina fine particles or silica / alumina mixed fine particles are known as materials that diffusely reflect ultraviolet light, and examples of use as a reflective film of a dielectric barrier discharge lamp are known. It cannot be shielded enough. Therefore, the light shielding is incomplete, the adhering scattered matter is solidified, and the discharge tube is damaged. In particular, distortion tends to concentrate on the wall surface located on the long side surface in the longitudinal direction (front-rear direction).

The present invention has been made in view of the above, and in a dielectric barrier discharge lamp for irradiating vacuum ultraviolet light, suppression of adhering to the wall surface located on the long side surface of the flying scattered matter to the discharge tube and solidification Reducing the amount of deposits is a technical issue.

A dielectric barrier discharge lamp according to the present invention includes a discharge tube that encloses a discharge gas for excimer light emission and irradiates ultraviolet rays downward through a lower wall plate having a flat surface, and an external portion of the discharge tube. In a dielectric barrier discharge lamp having an electrode on at least one side,
The wall surface located on the long side surface around the lower wall plate in the discharge tube is constituted by a light shielding member that shields at least 50% of ultraviolet rays. From the result of FIG. 6, it can be seen that the solidified deposit starts to decrease when the ultraviolet light shielding rate exceeds about 50%.

According to the dielectric barrier discharge lamp according to the present invention, it is possible to suppress the adhering of scattered matter flying on the wall surface of the discharge tube constituted by the light shielding member and to prevent the solidification. In particular, by constructing the wall surface located on the long side surface (or the four side surfaces including the short side surface) around the lower wall plate with a light shielding member, adhesion of scattered matter flying on the side surface or the upper surface with respect to the irradiation surface of the discharge tube or its Solidification is suppressed and the life of the discharge tube can be improved. If necessary, the upper wall plate may be made of the same light shielding member. Since a discharge tube that irradiates vacuum ultraviolet rays attaches a lot of scattered matter to the wall surface, a great effect can be expected.

The “discharge tube that irradiates ultraviolet rays downward through the lower wall plate” defines the shape of the discharge tube, which is a prerequisite for carrying out the present invention. This is the shortest and almost flat top and bottom wall plates facing each other up and down, which are almost in the shape of a rectangular box having a shape substantially parallel to each other, or “in an elongated cylinder, a part of the arc of the outer peripheral wall is crushed and flattened. Such as an arch-shaped curved surface portion and a flat plate-shaped flat portion that connects both end edges of the arc in the curved surface portion, etc., all have a lower wall plate having a flat portion instead of the front glass. And what is irradiated with ultraviolet rays through the lower wall board corresponds.

The light blocking ratio of the light blocking member constituting the wall of the discharge tube is preferably as high as possible. If the light blocking ratio is 70% or more, for example, 90% or more, the solidified deposits have a relative film thickness to reduce the solidification of the scattered matter. In some cases, it can be suppressed to 5% or less of 1000 hours of irradiation.

Here, the output intensity I of the light transmitted through the film having the film thickness t is obtained by using the input intensity I ₀ , the absorption coefficient α, and the film thickness t.
I = I ₀ · e ^−αt (Formula 1)
(However, e is the base of natural logarithm)
It is expressed. Since the transmittance is expressed as I / I ₀ , the light shielding rate is calculated as (1−I / I ₀ ).

In general, “shielding” means to block light, so it can occur when “shielding” is realized by “reflection”, “absorption”, or “refraction”. However, in the present invention, as a result, if the vacuum ultraviolet ray can not be blocked by 50% or more (more preferably 70% or more, more preferably 90% or more), the adhesion of scattered matter and its solidification can be prevented. It should be noted that no effect can be obtained. Further, the “light shielding member” is a member that blocks light, and may be composed of one kind of material or may be composed of two or more kinds of materials.

In addition, a dielectric barrier discharge lamp according to the present invention includes a discharge tube that encloses a discharge gas for excimer light emission, and irradiates ultraviolet rays downward through a lower wall plate having a flat surface. In a dielectric barrier discharge lamp having an electrode on at least one of the outside,
The wall surface located on the long side surface around the lower wall plate in the discharge tube is shielded so that the average illuminance of ultraviolet rays radiated from the wall surface to the outside of the discharge tube is 50 mW / cm ² or less when the lamp is turned on. It is characterized by comprising a light shielding member. From the results shown in FIG. 6, the solidified deposits decreased after the ultraviolet light shielding rate exceeded about 50%, that is, when the average illuminance of ultraviolet rays radiated to the outside of the discharge tube became 50 mW / cm ² or less. You can see that it is starting. In other words, it can be seen that the decrease starts when the average illuminance of ultraviolet rays radiated to the outside of the discharge tube becomes 50 mW / cm ² or less. More preferably, it is desirable to turn on the light so that the average illuminance of ultraviolet rays radiated to the outside of the discharge tube is 30 mW / cm ² or less, and more preferably, the light shielding member shields light so that it becomes 10 mW / cm ² or less. It is good to be composed of. The average illuminance is an average value when the surface illuminance of the discharge tube is measured at five locations. As will be described later, the average illuminance of the side wall surface can be calculated based on the average illuminance of the lower wall plate and the light shielding rate of the side wall surface.

A dielectric barrier discharge lamp lighting method according to the present invention includes a discharge tube in which discharge gas for excimer light emission is enclosed and irradiated with ultraviolet rays downward through a lower wall plate having a flat surface, and the discharge tube A method of lighting a dielectric barrier discharge lamp comprising an electrode on at least one of the outside of
The average illuminance of ultraviolet rays radiated from the wall surface located on the long side surface around the lower wall plate in the discharge tube to the outside of the discharge tube is 50 mW / cm ² or less. From the results shown in FIG. 6, the solidified deposits decreased after the ultraviolet light shielding rate exceeded about 50%, that is, when the average illuminance of ultraviolet rays radiated to the outside of the discharge tube became 50 mW / cm ² or less. You can see that it is starting. More preferably, lighting is performed so that the average illuminance of ultraviolet rays radiated to the outside of the discharge tube is 30 mW / cm ² or less, and more preferably, lighting is performed so as to be 10 mW / cm ² or less. desirable.

When the illuminance of light irradiating the object to be irradiated may be small, or when irradiating the object to be irradiated after collecting the light irradiated from the lower wall plate, the illuminance of the entire discharge lamp is lowered. Thus, the average illuminance of ultraviolet rays emitted from the wall surface located on the long side surface around the lower wall plate to the outside of the discharge tube can be set to 50 mW / cm ² or less. In addition to lowering the illuminance of the entire discharge lamp, the wall surface located on the long side surface around the lower wall plate is made of a light shielding member, so that the discharge from the wall surface located on the long side surface around the lower wall plate can be achieved. You may light so that the average illumination intensity of the ultraviolet-ray radiated | emitted to the exterior of a pipe | tube may be 50 mW / cm < ² > or less.

In the dielectric barrier discharge lamp according to the present invention, a member including a transparent member and a light shielding film can be used as the light shielding member. The light shielding film only needs to be disposed at a position where the ultraviolet rays irradiated to the outside through the transparent member can be shielded. For example, the light shielding film may be formed on the surface of the transparent member. A synthetic quartz plate or a fused quartz plate can be used as the transparent member. After the entire discharge tube is made of the same transparent member such as a synthetic quartz plate, a light shielding film is preferably formed on the wall surface of the discharge tube located on the long side surface around the lower wall plate. The plate and the transparent member are not necessarily the same member. Thus, by configuring the light shielding member with the transparent member and the light shielding film, the physical properties such as the strength of the discharge tube can be easily adjusted on the transparent member side, and the light shielding property against ultraviolet rays can be easily adjusted on the light shielding film side. it can.

Furthermore, as this transparent member, a fired product of slurry (turbid liquid) in which fine particles of oxide having ultraviolet light shielding properties are turbid in a solvent can be used. This light shielding film may be formed inside the discharge tube or outside. The primary particle diameter of the fine particles is preferably 3 μm or less. By using fine particles having a small particle size as the material of the light shielding film, it is possible to form a light shielding film in which particles are closely arranged and the space between the particles is small compared to the case where a material having a large particle size is used. As a result, since the probability that ultraviolet rays pass through the space between the particles decreases, the ultraviolet light shielding rate can be easily increased. Furthermore, the unevenness of the light shielding rate of the entire light shielding rate can be reduced.

As the solvent, alcohols (ethanol, isopropyl alcohol, n-butanol, etc.), xylene, toluene and the like can be used. In order to disperse the ultrafine particles in the solvent, a surfactant such as a polycarboxylic acid partial alkyl ester, a polyether, or a polyhydric alcohol ester may be added.

Preferably, the primary particle diameter of the oxide fine particles is 10 to 100 nm. If the particle diameter of the fine particles is larger than 100 nm, the dispersibility in the slurry is deteriorated, which may result in a non-uniform light shielding film. Furthermore, since the space between the particles is widened, the ultraviolet light shielding rate is lowered. Further, if the particle diameter of the fine particles is smaller than 10 nm, the surface energy of the particles is high, and the particles aggregate and precipitate in the slurry.

More preferably, the oxide fine particles are mainly composed of yttrium oxide (Y ₂ O ₃ ). Yttrium oxide has ultraviolet absorptivity and is an insulator. Therefore, when providing a light shielding film inside the discharge tube, it is possible to form a light shielding film that has ultraviolet light shielding properties and does not cause abnormal discharge in the discharge tube during discharge, and provides a light shielding film outside the discharge tube. In this case, it is not necessary to worry about the electrical contact with the electrode provided outside the discharge tube. In addition to yttrium oxide, ultrafine particles mainly composed of zinc oxide (ZnO) or titanium oxide (TiO ₂ ) coated with silica (SiO ₂ ) may be used. These materials are useful for vacuum ultraviolet light having a center wavelength of 172 nm when xenon gas is used as the discharge gas.

Further, it is preferable that the light shielding film used in the dielectric barrier discharge lamp according to the present invention shields light mainly by ultraviolet absorption. This is because the light shielding film can be made thin. The ultraviolet reflectivity is more dependent on the film thickness than the ultraviolet absorptivity. For this reason, in order to increase the light shielding rate to 50% or more with a light-shielding film having ultraviolet reflectivity, it is necessary to make the film thicker than when a light-shielding film having ultraviolet absorptivity is used. In particular, when the light shielding rate is 70% or more and 90% or more, the difference is remarkable. When a thick light-shielding film is formed on the long side wall around the lower wall plate, the heat retention effect of the discharge tube is increased, resulting in an increase in the temperature in the discharge tube when the lamp is turned on and a decrease in luminous efficiency. . Furthermore, the thicker the film, the easier it is for the light-shielding film to crack when the lamp is lit due to the difference in thermal expansion coefficient between the transparent member and the light-shielding film. Therefore, the thickness of the light shielding film is preferably 10 μm or less. Here, “mainly shielding light by ultraviolet absorption” means that the light shielding rate by “absorption” is larger than the light shielding rate by “reflection” or “refraction”. Examples of the material that shields light mainly by ultraviolet absorptivity include yttrium oxide (Y ₂ O ₃ ), zinc oxide (ZnO), zirconium oxide (ZrO ₂ ), and the like. Also good.

Alternatively, the lower wall plate may be formed of a synthetic quartz plate, while the four side surfaces (both side walls in the front-rear direction and the left-right direction) around the lower wall plate or the upper wall plate may be formed of a fused quartz plate. Since a fused quartz plate contains more impurities than synthetic quartz, the shielding rate against vacuum ultraviolet rays is usually 70% or more, and since it can be easily welded to synthetic quartz by heating, Suitable as a member.

Alternatively, the arc tube itself is composed entirely of a synthetic quartz plate, but the four side surfaces around the lower wall plate (both side walls in the front-rear direction and the left-right direction) or the surface of the upper wall plate until the light shielding rate becomes 70% or more, for example. You may roughen. Roughening is to increase the surface roughness compared to a mirror-finished wall. The surface is chemically eroded by contact with hydrofluoric acid or the like, and fine particles such as sandblast are sprayed. There is a method of roughening the surface by physically losing the specular state.

The dielectric barrier discharge lamp according to the present invention is an ultraviolet irradiation device by using a power supply device that outputs electric power for generating excimer light emission and a lead wire for supplying electric power from the power supply device. be able to. When irradiating an irradiated object having an organosilicon compound layer formed on the surface to be irradiated by such an ultraviolet irradiation device, in addition to the organic silicon compound originally suspended in the air, the irradiated object Since the organosilicon compound also comes from, the scattered matter is more likely to fly to the wall surface of the discharge tube. Therefore, when using the irradiated control object in which the layer of the organosilicon compound is formed on a part of the irradiated surface, the effect of suppressing the adhesion of the scattered material and the solidification preventing action become remarkable. The organosilicon compound may be used as an intermediate layer for improving the adhesion between the irradiated object and the resist when the resist is applied to the irradiated object.

According to the dielectric barrier discharge lamp of the present invention, the wall surface located on the long side surface or the four side surfaces around the lower wall plate in the discharge tube is composed of a light shielding member that shields at least 50% of ultraviolet rays. It is possible to suppress the adhering of scattered matter flying on the wall surface of the discharge tube constituted by the members and prevent solidification.

The perspective view which shows 1st Embodiment and abbreviate | omitted the elongate center part of the dielectric barrier discharge lamp 1A and 1B show a first embodiment, in which FIG. 1A is a cross-sectional view of a discharge tube 1a of FIG. 1 cut along a long central axis and viewed from the side, and FIG. 1B is a dielectric barrier discharge. Sectional view of the lamp in the longitudinal direction, (c) is a sectional view taken along line BB of (a) (A) and (b) both form an ultraviolet light shielding film on the inner wall surface located on the four side surfaces around the lower wall plate in the discharge tube 1 of the dielectric barrier discharge lamp shown in FIGS. Figure showing (A) And (b) shows the 2nd Embodiment of this invention and its modification, Comprising: Sectional drawing of the elongate direction of a dielectric barrier discharge lamp The perspective view which showed the 3rd Embodiment of this invention and abbreviate | omitted the long center part of the dielectric barrier discharge lamp A graph showing the relationship between the film thickness of solidified deposits and the ultraviolet light shielding rate Side sectional view of the ultraviolet irradiation device of the fourth embodiment (A) A barrier discharge lamp according to a fourth embodiment, which is a cross-sectional view in a plane perpendicular to the length direction of the discharge tube of the ultraviolet irradiation device of FIG. 7 (b) of the fourth embodiment shown in (a). First modification of barrier discharge lamp Second modification of the barrier discharge lamp of the fourth embodiment shown in FIG. Schematic diagram of experimental equipment Schematic diagram of measuring device

Hereinafter, embodiments of the present invention will be described with reference to the drawings. The same reference numerals are used for the same or similar members, or only the subscripts are displayed differently, and duplicated descriptions are omitted. However, the description of each embodiment is for understanding the technical idea of the present invention. Should not be construed as limited to the description of the embodiments.

(First embodiment)
1 and 2 show a first embodiment of the present invention and are perspective views in which a long central portion of a dielectric barrier discharge lamp is omitted. FIG. 2A is a cross-sectional view of the discharge tube 1a of FIG. 1 taken along the long central axis and viewed from the side. 2B is a cross-sectional view in the longitudinal direction of the dielectric barrier discharge lamp, that is, a cross-sectional view taken along line AA in FIG. 2A, and FIG. 2C is a cross-sectional view taken along line BB in FIG. It is line sectional drawing.

A discharge tube 1 of this dielectric barrier discharge lamp is made of a synthetic quartz glass having a substantially square box shape and a synthetic quartz glass having substantially the same shape as the cross section of the square tube 1a. The front and rear

end wall plates

1b and 1b are respectively welded and closed. Xenon gas is sealed inside. The square tube 1a is a rectangular tube having a vertical cross-sectional height of several tens of mm and a horizontal width of several tens of mm. The length in the front-rear direction is, for example, 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 project in advance from front and rear

end wall plates

1b and 1b, respectively, which are welded to the opening portions at both ends of the square tube 1a. Each tip tube 1c is a fused silica glass tube member 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 in the approximate 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 the opening portions at 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 almost the entire upper surface of the upper wall plate of the square tube 1a except for an uncoated portion for a sensor for inspecting the intensity of vacuum ultraviolet rays emitted from the dielectric barrier discharge lamp. Is done. 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.

Ultraviolet light shielding films 4 a obtained by firing a slurry containing yttrium oxide (Y ₂ O ₃ ) are provided on four inner wall surfaces located on the four side surfaces around the lower wall plate in the discharge tube 1. This film can block 172 nm vacuum ultraviolet light, and the light blocking rate can be adjusted by the film thickness. Then, an ultraviolet irradiation device is configured by connecting to a power supply device, and a dielectric barrier discharge lamp is turned on by applying a predetermined power to the electrode via a lead wire, and through this flat lower wall plate, FIG. In the direction of the arrows a) and (b), 172 nm vacuum ultraviolet rays are irradiated vertically downward in FIG. 2C.

3 (a) and 3 (b), an ultraviolet light shielding film is formed on the inner wall surface located on the four side surfaces around the lower wall plate in the discharge tube 1 of the dielectric barrier discharge lamp shown in FIGS. It shows how to do. First, the square tube 1a is tilted so that the side faces downward as shown in the figure, and a slurry containing yttrium oxide (Y ₂ O ₃ ) is injected from the tip tube 1c and dried. After carrying out this operation on both side surfaces and front and rear end wall plates, firing is performed at 500 ° C. for 30 minutes. Thereafter, the gas is discharged from the tip tube 1c, a discharge gas (for example, xenon gas) is injected, and the inside is filled with the discharge gas. And the front-end | tip part of both the tip pipe | tubes 1c is melt-sealed, and the inside is sealed. Thereafter, electrode metal is deposited and patterned, and finally magnesium fluoride (MgF ₂ ) is deposited to form a coating film for protecting the electrode, thereby completing the discharge tube. YAP10WT% -X480 (manufactured by CIK Nanotech) containing 10% by weight of yttrium oxide having a primary particle size of 33 nm is used as a stock solution, and this stock solution diluted with n-butanol is used as a slurry. By changing the degree of dilution, the light shielding rate of the ultraviolet light shielding film can be changed.

-Experiment-
Here, six types of discharge tubes differing only in the film thickness of yttrium oxide according to the manufacturing method described above were prototyped, and the amount of solidified deposit (white powder) adhering to the tube wall and the degree of solidification were examined. . The experimental conditions are as follows.
(1) Test lamp A. Prototype lamp 1 ... Side ultraviolet light shielding film (yttrium oxide) formation Light shielding rate 99% (no dilution)
Average illuminance from the lower wall plate of 101 mW / cm ²
Average illuminance from side wall surface 1 mW / cm ²
B. Prototype lamp 2 ... Side UV shielding film (yttrium oxide) formation Light shielding rate 90% (4 times dilution)
Average illuminance from the lower wall plate of 98 mW / cm ²
Average illuminance from the side wall surface 10 mW / cm ²
C. Prototype lamp 3 ... Side ultraviolet light shielding film (yttrium oxide) formation Light shielding rate 71% (6 times dilution)
Average illuminance from the lower wall plate of 101 mW / cm ²
Average illuminance from the side wall of 29 mW / cm ²
D. Prototype lamp 4 ... Side ultraviolet light shielding film (yttrium oxide) formation Light shielding rate 56% (diluted 10 times)
Average illuminance from lower wall plate 107mW / cm ²
Average illumination from the side wall surface 47 mW / cm ²
E. Prototype lamp 5 ... Side ultraviolet light shielding film (yttrium oxide) formation Light shielding rate 30% (20 times dilution)
Average illuminance from the lower wall plate of 104 mW / cm ²
Average illuminance from the side wall surface 73 mW / cm ²
F. Conventional product ・・・ Shading rate 0%
Average illuminance from lower wall plate 109mW / cm ²
Average illuminance from the side wall surface of 109 mW / cm ²
(2) Power source: lamp applied peak voltage 3.8 kV, driving frequency 70 kHz (generally rectangular wave)

(3) Irradiation equipment:
FIG. 10 shows a schematic diagram of the experimental apparatus. The arrows indicate the direction of fluid flow. As shown in FIG. 10, the irradiation tool 50 includes one of the above-mentioned six kinds of test lamps 54 disposed in a container 56 between a dummy substrate 53 and a punching metal plate 55. Nitrogen gas containing HMDS is configured to flow in air A1 and A2 from the side of the container 56 and exhaust the exhaust gas E after irradiation. The bubbling container 51 stores the HMDS 52 therein. Nitrogen gas containing HMDS is obtained by flowing nitrogen gas N (N ₂ ) into the HMDS 52 with a nozzle, and flows into the irradiation tool 50 through a pipe.
At this time, the content of the HMDS is such that the bubble size of the nitrogen gas passing through the HMDS 52 and the rising distance of the bubble, that is, the nitrogen gas is HMDS 52 while the temperature of the bubbling container 51 is kept constant at 20 ° C. It is adjusted by the distance from the tip of the nozzle flowing into the liquid to the liquid level. Since the HMDS 52 decreases with the inflow of nitrogen gas N, it is appropriately replenished until the experiment is completed.
(4) HMDS: Always supply (5) Total nitrogen amount: 50 L / min
(6) Lighting time: 1000 hours

(7) Illuminance measurement:
The surface illuminance of the lower wall plate of the discharge tube is measured at five locations with an ultraviolet illuminance meter (UIT150 / VUV-S172, manufactured by USHIO), and the average value is defined as the average illuminance. At that time, the measurement location is a region in which the pair of electrodes face each other (a region corresponding to the discharge space) is equally divided into five in the longitudinal direction, and is near the center. Accordingly, the measurement points are set at approximately equal intervals.
Here, the average illuminance of the side wall surface is calculated using the average illuminance of the lower wall plate and the light shielding rate (1-I / I ₀ ) of the side wall surface. When the light shielding rate of the side wall surface is represented by (1−I / I ₀ ), the transmittance of the side wall surface is I / I ₀ , so the average illuminance E of the lower wall plate and the transmittance I / I of the side wall surface By multiplying by ₀ , the average illuminance of the side wall surface is obtained.

-result-
Table 1 shows the experimental results after 1000 hours. The prototype lamp 2 which shielded 90% of UV rays on the side face had a small amount of white powder adhering, the vitrification film thickness at that time was 15 μm, and vitrification (solidification) was slightly observed. Prototype lamp 3 that shielded 71% of ultraviolet rays on the side also had a small amount of white powder, but the vitrification film thickness at that time was 69 μm, and a little vitrification was observed. The prototype lamp 4 which shielded the ultraviolet rays on the side by 56% had a larger white powder adhesion amount than the prototype lamp 3, and the vitrified film thickness at that time was 159 μm. On the other hand, the prototype lamp 5 which shielded 30% of ultraviolet rays on the side surface had a larger white powder adhesion amount than the prototype lamp 4, and the vitrified film thickness at that time was 306 μm. Moreover, the conventional lamp which did not shield the ultraviolet rays on the side face had a very large amount of white powder adhered, and the vitrified film thickness at that time was 300 μm. From these facts, the following became clear.
1. The side shading has the effect of reducing the amount of white powder attached.
2. Shading of 56% or more of the side surface has an effect of preventing vitrification (solidification). In view of the tendency, it is recognized that the effect is effective at 50% or more. It is remarkable at 71% or more, and more remarkable at 90% or more. This result is in good agreement with the graph of FIG.

As described above, even if an organosilicon compound adheres to the side surface of the discharge tube, it is possible to suppress a strong glassy deposit by preventing the chemical reaction from proceeding as much as possible by shielding ultraviolet rays. It is considered that the amount of the adhered material itself is reduced because white powder itself is difficult to form in the space near the side surface.

(Second Embodiment)
FIGS. 4A and 4B show a second embodiment of the present invention and its modification, and are sectional views in the longitudinal direction of a dielectric barrier discharge lamp. In the first embodiment, the mode in which the light shielding film is provided on the inner wall surface located on the four side surfaces around the lower wall plate has been described. However, as shown in this figure, the ultraviolet light shielding film 4b is provided on the outer periphery of the discharge tube. Also good. Although not shown, light shielding films are also provided on the front and rear end faces. When a metal oxide sintered body is used as the light shielding film, it is preferable to perform a coating, drying and firing process of the light shielding film before the electrode forming process. This is because the firing process after the electrode pattern is formed may cause inconveniences such as deterioration of the electrode. However, if a heat treatment step is unnecessary, a light shielding film may be formed on the side surface of the discharge tube after the electrodes are formed. It is considered that the degree of freedom in the manufacturing process is increased as compared with the case where a light shielding film is formed inside the discharge tube, and the material selection range of the light shielding film is widened.

-Modification-
Alternatively, as shown in FIG. 4 (b), the inner wall surface itself located on the four side surfaces around the lower wall plate may be formed of a light shielding member and bonded to the upper and lower wall plates by welding or glass frit. In this case, the lower wall plate may be composed of a synthetic quartz plate, while the four side surfaces (both wall surfaces in the front-rear direction and the left-right direction) around the lower wall plate or the upper wall plate may be composed of a fused quartz plate 4c. Fused quartz is a natural quartz (natural silica) melted and solidified into a plate shape. Since it contains a large amount of impurities, it has a high light shielding ratio of 70% or more for vacuum ultraviolet rays and is heated. This is because welding with synthetic quartz is easy. The same effect can be obtained by using a ceramic plate instead of natural quartz as the light shielding member. In this case, glass frit can be used as a bonding agent because it cannot be welded to synthetic quartz.

By adopting such a configuration, even if an organosilicon compound adheres to the side surface of the discharge tube, the chemical reaction does not proceed as much as possible by shielding ultraviolet rays so that a strong vitreous deposit can be formed. Formation can be suppressed.

(Third embodiment)
FIG. 5 shows a third embodiment of the present invention, and is a perspective view in which a long central portion of a dielectric barrier discharge lamp is omitted. FIG. 5A is a cross-sectional view of the discharge tube 1a of FIG. 1 taken along the long central axis and viewed from the side. 5B is a cross-sectional view of the dielectric barrier discharge lamp in the longitudinal direction, that is, a cross-sectional view taken along line AA in FIG. 5A, and FIG. 5C is a cross-sectional view taken along line BB in FIG. It is line sectional drawing.

In the third embodiment, the arc tube itself is composed entirely of a synthetic quartz plate. However, the four side surfaces (both side walls in the front-rear direction and the left-right direction) around the flat lower wall plate or the surface of the upper wall plate are shielded, for example. The surface is roughened until the rate reaches 70% or more. Roughening is to increase the surface roughness of the mirror-like wall surface. As a roughening method, for example, a method of roughening the surface by chemically eroding by contact with hydrofluoric acid. And a method of roughening the surface by physically losing the specular state by spraying fine particles such as sandblast.

As shown in FIG. 5 (a), rough surfaces 4d having an ultraviolet shielding effect are formed on the four side surfaces (both side walls in the front-rear direction and the left-right direction) around the lower wall plate. In the method of contacting hydrofluoric acid, as in the slurry injecting step described in the first embodiment, hydrofluoric acid is injected from the tip tube 1c into the discharge tube, and the four side surfaces around the lower wall plate (front-rear direction and left-right direction). The two side walls in the direction) or the upper wall plate may be dissolved with hydrofluoric acid to roughen the surface. Even if it does in this way, even if a vacuum ultraviolet ray is no longer exposed from a side part, even if an organosilicon compound adheres to the side of a discharge tube, it is strong by preventing a chemical reaction from progressing there as much as possible by shielding ultraviolet rays. Glassy deposits can be suppressed.

For the formation of the rough surface 4d having an ultraviolet light shielding effect, physical treatment by spraying sandblast may be used instead of chemical treatment using hydrofluoric acid.

(Fourth embodiment)
In the first to third embodiments described above, the dielectric barrier discharge lamp having the rectangular tube shape and the long rectangular tube and the ultraviolet irradiation apparatus using the dielectric tube discharge lamp have been described. However, the present invention is not limited to such a shape, and may be a semi-open type ultraviolet irradiation device that irradiates vacuum ultraviolet rays downward through a lower wall plate having no flat glass and having a flat surface. All are applicable. In the fourth embodiment, another embodiment of the present invention will be described.

7 and 8 are side sectional views of the ultraviolet irradiation device, and FIG. 8 is a sectional view in a plane perpendicular to the length direction of the discharge tube of the ultraviolet irradiation device of FIG. The ultraviolet irradiation device 10 shown in FIG. 7 includes a barrier discharge lamp 11 and an AC power supply device 22 connected via

lead wires

20 and 21. The discharge tube 12 of the barrier discharge lamp 11 has a double tube structure composed of an outer tube portion 13 and an inner tube portion 14, and an outer tube portion 13 and an inner tube portion 14 inserted into the outer tube portion 13. It has.

As shown in FIG. 8, the outer tube portion 13 includes an arch-shaped curved surface portion 15 that is flattened by crushing a part of the arc of the outer peripheral wall in an elongated cylinder, and both end edges of the arc in the curved surface portion 15. A flat plate-like flat portion 16 (lower wall plate) is provided. Vacuum ultraviolet rays are irradiated through the flat portion 16. The corner portion 15A where the curved surface portion 15 and the flat portion 16 are joined is rounded. On the other hand, the inner tube portion 14 has a cylindrical shape smaller in diameter than the outer tube portion 13, and the outer tube portion 13 and the inner tube portion 14 that are arranged at the center position in the lateral direction on the inner wall surface of the flat portion 16. Are joined to each other at both ends, and a discharge gas such as xenon gas is enclosed in a discharge space 17 surrounded by both.

Electrodes

18 and 19 are provided outside the discharge tube 12. Of the pair of electrodes, the upper electrode 18 is made of a metal film fixed to the outer wall surface of the curved surface portion in the outer tube portion 13. In addition, as a material of the upper electrode 18, it is preferable to use a material that reflects ultraviolet rays. As such a material, for example, aluminum can be used. The film thickness of the upper electrode 18 is preferably higher in reflectance, and is preferably at least 70% or more, more preferably 90% or more so as not to transmit ultraviolet rays to the outside. On the other hand, the lower electrode 19 is made of a nickel wire and is inserted into the inner tube portion 14 over almost the entire length. The lower electrode 19 is provided at a position equidistant from each point on the upper electrode 18. One end portions of the

lead wires

20 and 21 are connected to the

electrodes

18 and 19, and the other end portions of the

lead wires

20 and 21 are connected to an AC power supply apparatus.

As shown in FIG. 8 (a), slurry containing yttrium oxide (Y ₂ O ₃ ) is fired on the four inner wall surfaces located on the four side surfaces around the flat portion 16 in the outer tube portion 13. An ultraviolet light shielding film 4e is provided. This film can block 172 nm vacuum ultraviolet light, and the light blocking rate can be adjusted by the film thickness.

The ultraviolet light shielding film 4e is preferably composed of a light shielding member that shields light at least 50% or more, more preferably 70% or more, and still more preferably 90% or more. Further, as illustrated in FIG. 8, it is preferable to provide an ultraviolet light shielding film so as to partially overlap the end portion 18 </ b> A of the upper electrode 18 that also functions as an ultraviolet reflection film. In this way, ultraviolet rays leaking outside the outer tube portion 13 can be reliably shielded by the ultraviolet reflecting film 4e, and even if scattered matter adheres to the surface of the outer tube portion 13, it is solidified as much as possible. You can prevent it from progressing. This also applies to the following

modifications

1 and 2.

-Modification 1-
FIG. 8B shows a first modification of the barrier discharge lamp of the fourth embodiment shown in FIG. As shown in this figure, the barrier discharge lamp 30 has a discharge tube 31 having a single tube structure without an inner tube portion, and the upper electrode 34 is formed on an arch-shaped curved portion 32 of the discharge tube 31. The lower electrode 35 is provided on the flat portion 33 (lower wall plate). Ultraviolet light shielding films 4f obtained by firing a slurry containing yttrium oxide (Y ₂ O ₃ ) are provided on four inner wall surfaces located on the four side surfaces around the flat portion 33. This film can block 172 nm vacuum ultraviolet light, and the light blocking rate can be adjusted by the film thickness.

-Modification 2-
FIG. 9 shows a second modification of the barrier discharge lamp of the fourth embodiment shown in FIG. As shown in this figure, in this barrier discharge lamp 40, the structure of the discharge tube 41 is a double tube structure comprising an outer tube portion 42 and an inner tube portion 43, and the upper electrode 47 is formed of the discharge tube 41. Provided on the arch-shaped curved surface portion 44, the lower electrode 48 is inserted into the inner tube portion 14 over almost the entire length. The lower electrode 48 is provided at a position equidistant from each point on the upper electrode 47. One end portions of the

lead wires

20 and 21 are connected to the

electrodes

47 and 48, and the other end portions of the

lead wires

20 and 21 are connected to an AC power supply apparatus. In addition, an auxiliary electrode 49 is provided over the entire outer surface of the outer tube portion of the flat portion 45 (lower wall plate) of the discharge tube 41. The auxiliary electrode 49 assists the main discharge between the pair of

electrodes

47 and 48. The auxiliary electrode 49 is formed in a mesh shape so as not to block light emitted from the inside of the discharge tube 41 as much as possible, and is provided over the entire length of the discharge tube 41 in the length direction.

The four inner wall surfaces positioned on the four side surfaces around the flat portion 45 are provided with an ultraviolet light shielding film 4g obtained by firing a slurry containing yttrium oxide (Y ₂ O ₃ ). This film can block 172 nm vacuum ultraviolet light, and the light blocking rate can be adjusted by the film thickness.

As described above, the dielectric barrier discharge lamp according to the present invention is not limited to a strictly rectangular box-shaped discharge tube in a strict sense, as long as it is a semi-open type ultraviolet irradiation device that does not require a front glass. It can also be applied to arcuate discharge tubes. Furthermore, in this case, an auxiliary electrode may be provided in the case of a double tube structure regardless of whether the structure of the discharge tube is a double tube structure or a single tube structure.

Since the dielectric barrier discharge lamp according to the present invention is a substantially rectangular box-shaped dielectric barrier discharge lamp that does not require a front glass, not only can the manufacturing cost be reduced, but also on both side walls in the longitudinal direction (front-rear direction). Industrial applicability is great in that the strain can be prevented from being concentrated and the life of the discharge tube can be extended.

DESCRIPTION OF SYMBOLS 1 Discharge tube 2 Upper electrode 3 Lower electrode 4 Light shielding member 4a Ultraviolet light shielding film 4b Ultraviolet light shielding film 4c Fused quartz plate 4d Rough surface with ultraviolet light shielding action 4e to 4g Ultraviolet light shielding film 10

Ultraviolet irradiation device

11, 30, 40

Barrier discharge lamp

12, 31, 41

Discharge tube

13, 42

Outer tube portion

14, 43

Inner tube portion

15, 32 Arched

curved surface portion

16, 33, 45 Flat portion 17

Discharge space

18, 34, 47

Upper electrode

19, 35, 48

Lower portion Electrode

20, 21 Lead wire 22 AC power supply device 49 Auxiliary electrode 50 Irradiation instrument 51 Bubbling container 52 HMDS (hexamethylene disilazane)
53 Dummy substrate (SUS)
54 Test Lamp 55 Punching Metal Plate 60 Measuring Device 61 Discharge Tube 62 Surface Plate 63 Discharge Tube Fixing Stand 64 Micrometer Fixing Stand 65 Micrometer A1, A2 Air N Nitrogen Gas E Exhaust Gas

Claims

Dielectric barrier discharge with discharge gas for excimer light emission inside, a discharge tube that irradiates ultraviolet rays downward through a lower wall plate having a flat surface, and an electrode on at least one outside of the discharge tube In the ramp,
A dielectric barrier discharge lamp characterized in that a wall surface located on a long side surface around a lower wall plate in the discharge tube is composed of a light shielding member that shields at least 50% of ultraviolet rays.
2. The dielectric barrier discharge lamp according to claim 1, wherein the light shielding member has a light shielding ratio of 70% or more.
2. The dielectric barrier discharge lamp according to claim 1, wherein the light shielding member has a light shielding ratio of 90% or more.
Dielectric barrier discharge with discharge gas for excimer light emission inside, a discharge tube that irradiates ultraviolet rays downward through a lower wall plate having a flat surface, and an electrode on at least one outside of the discharge tube In the ramp,
The wall surface located on the long side surface around the lower wall plate in the discharge tube is shielded so that the average illuminance of ultraviolet rays radiated from the wall surface to the outside of the discharge tube is 50 mW / cm 2 or less when the lamp is turned on. A dielectric barrier discharge lamp comprising a light shielding member.
The wall surface located on the long side surface around the lower wall plate in the discharge tube is shielded so that the average illuminance of ultraviolet rays radiated from the wall surface to the outside of the discharge tube is 30 mW / cm 2 or less when the lamp is turned on. 5. The dielectric barrier discharge lamp according to claim 4, wherein the dielectric barrier discharge lamp comprises a light shielding member.
The wall surface located on the long side surface around the lower wall plate in the discharge tube is shielded so that the average illuminance of ultraviolet rays radiated from the wall surface to the outside of the discharge tube is 30 mW / cm 2 or less when the lamp is turned on. 5. The dielectric barrier discharge lamp according to claim 4, wherein the dielectric barrier discharge lamp comprises a light shielding member.
Dielectric barrier discharge with discharge gas for excimer light emission inside, a discharge tube that irradiates ultraviolet rays downward through a lower wall plate having a flat surface, and an electrode on at least one outside of the discharge tube In the lighting method of the lamp,
Lighting of a dielectric barrier discharge lamp characterized in that the average illuminance of ultraviolet rays radiated to the outside of the discharge tube from the side surface located on the long side surface around the lower wall plate of the discharge tube is 50 mW / cm 2 or less Method.
8. The dielectric according to claim 7, wherein an average illuminance of ultraviolet rays radiated to the outside of the discharge tube from a side surface located on a long side surface around the lower wall plate in the discharge tube is 30 mW / cm 2 or less. How to turn on the body barrier discharge lamp.
8. The dielectric according to claim 7, wherein an average illuminance of ultraviolet rays radiated to the outside of the discharge tube from a side surface located on a long side surface around the lower wall plate in the discharge tube is 10 mW / cm 2 or less. How to turn on the body barrier discharge lamp.
The dielectric barrier discharge lamp according to claim 1 or 4, wherein the light shielding member includes a transparent member and a light shielding film.
11. The dielectric barrier discharge lamp according to claim 10, wherein the light shielding film is composed of a fired product of slurry (turbid liquid) in which fine particles of oxide having ultraviolet shielding properties are made turbid in a solvent.
12. The dielectric barrier discharge lamp according to claim 11, wherein a primary particle diameter of the oxide fine particles is 10 to 100 nm.
12. The dielectric barrier discharge lamp according to claim 11, wherein the oxide fine particles are mainly composed of yttrium oxide.
11. The dielectric barrier discharge lamp according to claim 10, wherein the light shielding film shields light mainly by ultraviolet absorption.
The dielectric barrier discharge lamp according to claim 10, wherein the light-shielding film has a thickness of 10 µm or less.
2. The lower wall plate is composed of a synthetic quartz plate, and both side wall surfaces or upper wall plates in the front-rear direction and the left-right direction of the four side surfaces around the lower wall plate are composed of a fused quartz plate. Or dielectric barrier discharge lamp according to 4
A roughening film having roughened front and rear side walls on the four side surfaces around the lower wall plate, the roughening film being front and rear on the four side surfaces around the lower wall plate. Both side walls in the direction and left and right direction are made of synthetic quartz,
5. The dielectric barrier discharge according to claim 1, wherein the front and rear side surfaces and the left and right side wall surfaces of the four side surfaces around the lower wall plate are roughened films roughened with hydrofluoric acid. lamp.
A roughening film having roughened front and rear side walls on the four side surfaces around the lower wall plate, the roughening film being front and rear on the four side surfaces around the lower wall plate. 5. The dielectric barrier discharge lamp according to claim 1, wherein sandblast is sprayed on both side walls in the horizontal direction.
The dielectric barrier discharge lamp according to claim 1 or 4,
An ultraviolet irradiation device comprising: a power supply device that outputs electric power for generating excimer light emission in the lamp; and a lead wire for supplying electric power from the power supply device.
21. The ultraviolet irradiation apparatus according to claim 19, wherein a layer containing an organosilicon compound is formed on a part of the irradiated surface of the irradiated object of the irradiation apparatus.