JP2006032242A - Two-dimensional array dielectric barrier discharge device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To stabilize light emission of a two-dimensional array dielectric barrier discharge lamp, enhance the light emission efficiency, improve the illuminance, elongate the life, and allow safe manufacturing and handling. <P>SOLUTION: A container of the two-dimensional array dielectric barrier discharge lamp has a light taking-out window for taking out excimer light. A gas for discharge is filled in the discharge container so that excimer molecules are formed by the dielectric barrier discharge. A first electrode is provided with a large number of discharge openings which directly contact with the gas for discharge, and a dielectric layer which contacts with the first electrode. The discharge opening is covered with an MgO film, and a ceramic insulating film is laminated between the MgO film and the first electrode. A second electrode is disposed opposing to the first electrode through the dielectric layer. Based on a corresponding relation, which provides a maximum light emission efficiency, between the opening area of the discharge openings and the pressure of the gas for discharge, the pressure of the gas for discharge is set at an optimal value corresponding to the opening area in the range of (1 atm, 0.6 mm<SP>2</SP>) to (3 atm, 7.1 mm<SP>2</SP>). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a two-dimensional array type dielectric barrier discharge device, and more particularly to a two-dimensional array type dielectric barrier discharge device that forms excimer molecules by dielectric barrier discharge and uses ultraviolet rays emitted from the excimer molecules, and a lamp thereof. About.

  Lamps using plasma discharge are applied to semiconductor substrate exposure processes such as VLSI, environmental fields such as surface clean treatment with ozone and dissociated oxygen, display light sources, and light sources such as illumination. In particular, excimer lamps using dielectric barrier discharge, which is known for quartz glass double tube structure, have 126nm, 146nm, 172nm, 222nm, 308nm, etc. that are not found in conventional low-pressure mercury lamps and high-pressure arc discharge lamps. Single wavelength light that is particularly useful in the manufacturing process can be selectively extracted with high efficiency.

  The excimer lamp has 5 layers of inner electrode, dielectric (quartz glass), discharge gas region, dielectric (quartz glass), outer electrode (network electrode), or inner electrode, discharge gas region, dielectric (quartz glass). , Consisting of four layers of outer electrodes (mesh electrodes). In the discharge gas region where excimer molecules can be formed, excimer light obtained by dielectric barrier discharge is used as light leaking from an external electrode (network electrode). The time until the lamp is lit stably is short, and the advantages of high brightness, illuminance uniformity, and long life are superior to conventional lamps.

  In the field of PDP (plasma display panel), it is used as an ultraviolet light source for emitting fluorescent paint. The basic structure of the PDP is a three-layer structure of a metal electrode having a thickness of several microns, a dielectric, and a metal electrode. In order to obtain a light source that is compact and has good optical characteristics, a multilayer electrode structure has been proposed. However, the efficiency of converting electrical energy into light energy is poor, about 1/10 that of fluorescent lamps. Recently, efficiency has been improved by increasing the frequency.

  Excimer molecules are based on one excited atom and are formed by three-body collisions with the other two base atoms. In a high pressure noble gas, the probability of a three-body collision increases, so excimer molecules are efficiently generated. To increase the intensity of the excimer light, it is operated at a pressure higher than atmospheric pressure. In a high-pressure gas atmosphere, as the breakdown voltage rises, it becomes easier to shift from glow discharge to arc discharge, and stable discharge cannot be established.

  The excimer lamp has a large discharge gap due to its structure. Therefore, it is necessary to apply a high voltage to increase the brightness in high-pressure gas. However, if a high voltage is applied, the glow discharge is shifted to the arc discharge, and the brightness cannot be increased. This is because the discharge gap is contained in the discharge gap itself, and the rare gas region that is the discharge space and the quartz glass cannot be thinned. Since the capacitance is large, the loss of energy input to the discharge is large and the luminous efficiency is poor. In order to prevent the loss of discharge energy and increase the luminous efficiency, it is necessary to make the dielectric thin, but the thickness of the dielectric cannot be reduced to 1 mm or less. It is difficult to increase the light emission efficiency by reducing the discharge gap by thinning the dielectric. Since the light distribution of the excimer lamp is not uniform on the light emitting surface, an optical system is required to uniformly irradiate the surface irradiation target with ultraviolet rays. The optical system has a problem of high cost. Further, since an optical system is required, the light source cannot approach the irradiation target. There is a problem that strong light cannot be used because the light source cannot approach the irradiation object.

  Therefore, the present inventors have proposed an excimer lamp that avoids these problems and stably performs glow discharge in high-pressure gas to improve luminous efficiency and increase brightness in Non-Patent Documents 1 and 2. . The two-dimensional array type rare gas micro-discharge device disclosed in Non-Patent Document 1 is composed of about 60 holes with a diameter of 100 μm arranged in a two-dimensional array in a 3 mm × 5 mm region. It is. The dielectric is mica. Discharge occurs at the opening of the electrode. Stable glow discharge can be obtained at 1 atm of Ar, Kr, and Xe. Vacuum ultraviolet light shows a band-like spectrum peculiar to a rare gas excimer. When the pressure is increased at 4.5 kV, the emission intensity initially increases, but decreases at about 10 atmospheres or more. When the applied voltage is increased, the pressure value of maximum light emission is also increased.

The two-dimensional array type excimer light source disclosed in Non-Patent Document 2 is a microscale barrier discharge device as shown in FIG. A 50 μm thick stainless steel electrode having openings of 100 μm in diameter in the range of 3 mm × 5 mm at intervals of 1 mm in the horizontal direction and 120 μm in the vertical direction is referred to as a light emitting electrode. The dielectric is mica having a thickness of 50 to 150 μm. This two-dimensional array type barrier discharge device is superior in operation in a high-pressure atmosphere and has a luminous efficiency several times higher than a conventional quartz double-tube dielectric barrier discharge lamp.
Proceedings of the 49th Japan Society of Applied Physics (292.3 Tokai University Shonan Campus) 29a-D-7 “Characteristics of two-dimensional array type rare gas microdischarge for vacuum ultraviolet light source”. 17th Light Source Physical Properties and Its Application Study Material “Development of Two-Dimensional Array Excimer Light Source”, pp.89-95, 2002.12.

  However, in the conventional two-dimensional array type barrier discharge device disclosed in Non-Patent Documents 1 and 2, the light emission is unstable in time and space depending on the gas pressure and the size of the opening area corresponding to the unit of the light emitting part. Or excimer molecules may not be produced at all. When high-pressure gas is sealed in order to stabilize light emission, the dielectric breakdown voltage and the discharge sustaining voltage are also increased, so that the concentration of the electric field is concentrated on a local portion, resulting in arc discharge. In order to maintain a stable glow discharge in which arc discharge does not occur, it is necessary to adapt the conditions of gas pressure and discharge opening area where the electric field is not concentrated locally.

  In addition, assuming a flat light source, there is a problem that a lamp filled with high-pressure gas may rupture during manufacture or handling. The possibility of lamp rupture due to mechanical defects is a serious problem as compared to short arc lamps, low-pressure mercury lamps and metal halide lamps which are spherical lamps. Therefore, there is a need for a high-efficiency flat lamp with a pressure that can be manufactured safely and can be used safely by consumers.

  An object of the present invention is to solve the above problems and to realize a two-dimensional array type dielectric barrier discharge device and lamp that emit light stably, have high luminous efficiency, and can be manufactured and handled safely.

In order to solve the above problems, in the present invention, a discharge vessel, a discharge gas filled in the discharge vessel so that excimer molecules are formed by dielectric barrier discharge, and a discharge opening in contact with the discharge gas A two-dimensional array comprising: a first electrode provided with a plurality of electrodes; a dielectric layer provided in contact with the first electrode; and a second electrode disposed opposite the first electrode with the dielectric layer interposed therebetween. (Gas pressure = 1 atm, Opening area = 0.6 mm ² ) to (Gas) based on the correspondence relationship between the opening area of the discharge opening and the pressure of the discharge gas that can obtain the maximum luminous efficiency of the type dielectric barrier discharge device The pressure of the discharge gas is set to an optimum value corresponding to the opening area within the range of pressure = 3 atm, opening area = 7.1 mm ² ). With this configuration, the two-dimensional array type dielectric barrier discharge device can be prevented from rupturing, and the efficiency can be improved.

  Further, the discharge opening was covered with an insulating film of MgO or aluminum nitride. With this configuration, the secondary electron emission effect is improved, and the efficiency of the two-dimensional array type dielectric barrier discharge device is increased.

  Further, an electrically insulating film having a high melting point of ceramic or silica glass was laminated between the insulating film and the first electrode. With such a configuration, it is possible to prevent the electrode from being sputtered due to discharge, and the luminous efficiency is increased and the life is extended.

Also, a discharge vessel having a light extraction window for extracting excimer light, a discharge gas filled in the discharge vessel so that excimer molecules are formed by dielectric barrier discharge, and a discharge in contact with the discharge gas A first electrode provided with a large number of openings, a dielectric layer provided in contact with the first electrode, and a second electrode disposed opposite the first electrode with the dielectric layer interposed therebetween. Based on the correspondence relationship between the opening area of the discharge opening and the pressure of the discharge gas that can obtain the maximum luminous efficiency of the three-dimensional array type dielectric barrier discharge lamp (gas pressure = 1 atm, opening area = 0.6 mm ² ) to Within the range of (gas pressure = 3 atm, opening area = 7.1 mm ² ), the pressure of the discharge gas is set to an optimum value corresponding to the opening area. With this configuration, the two-dimensional array type dielectric barrier discharge lamp can be prevented from rupturing, and the luminous efficiency is improved.

  By setting the opening area corresponding to the gas pressure so that the luminous efficiency is maximized, it is possible to realize a two-dimensional array type dielectric barrier discharge device and lamp that can always stably discharge and emit light with high efficiency. An insulating film of MgO film or aluminum nitride is provided on the electrode surface or the dielectric surface, and an insulating film made of ceramic coating or quartz glass coating is laminated between the electrode and the dielectric, thereby providing a two-dimensional array type dielectric barrier. The luminous efficiency of the discharge device and the lamp can be improved and the life can be extended.

  Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to FIGS.

Embodiments of the present invention include a discharge vessel having a light extraction window for extracting excimer light, a discharge gas filled in the discharge vessel so that excimer molecules are formed by dielectric barrier discharge, and a discharge vessel. A first electrode provided with a number of discharge openings in direct contact with the gas, a dielectric layer provided in contact with the first electrode, and a second electrode disposed opposite the first electrode with the dielectric layer interposed therebetween Electrode, the correspondence between the pressure of the discharge gas and the opening area of the discharge opening is (1 atm, 0.6 mm ² ) to (3 atm, 7.1 mm ² ), and the discharge opening is covered with an MgO film. , A two-dimensional array type dielectric barrier discharge lamp in which a ceramic insulating film is laminated between an MgO film and a first electrode.

  FIG. 1 is a cross-sectional view of a two-dimensional array type discharge lamp in an embodiment of the present invention. In FIG. 1, the first electrode 1 is an electrode having a large number of holes disposed on the upper surface of a dielectric 2. The dielectric 2 is a plate-like mica disposed on the upper surface of the second electrode 3. The dielectric 2 may be a material other than mica. The second electrode 3 is a flat electrode without a hole. The opening 4 is a large number of holes provided in the first electrode 1. The discharge vessel 5 is a vessel that covers these electrodes and dielectric. Although not shown, the discharge vessel 5 is provided with a light extraction window for extracting excimer light. The discharge space 6 is a space formed between the discharge vessel 5 and the first electrode 1. A gas in which excimer molecules are formed by discharge, for example, argon gas, is sealed in the discharge space 6. An AC power source E for forming an AC electric field is connected between the first electrode 1 and the second electrode 3. In this way, in a structure in which a continuous layer of dielectric 2 is sandwiched between the first electrode 1 and the second electrode 3, the first electrode 1 When an AC voltage is applied between the second electrode 3 and the AC power source E, excimer light A is generated on the surface of the dielectric 2 that is the opening 4 of the first electrode 1. In such a two-dimensional array type discharge lamp, the correspondence relationship between the discharge gas pressure that gives the maximum luminous efficiency of the excimer emission A and the opening area of the secondary electrode 3 is obtained and set.

  A method for obtaining the correspondence between the pressure of the discharge gas and the opening area of the discharge opening of the two-dimensional array type discharge lamp in the embodiment of the present invention configured as described above will be described. The opening diameter of the first electrode 1 of the two-dimensional array type discharge lamp # 1 is set to 50 μm. The opening diameter of the first electrode 1 of the discharge lamp # 2 is 150 μm. The opening diameter of the first electrode 1 of the discharge lamp # 3 is set to 500 μm. The thickness of the dielectric 2 (mica) of each discharge lamp is 150 μm, and the thickness of the first electrode and the second electrode is 20 μm. These discharge lamps are discharged in an Ar gas atmosphere of 1 to 15 atm, and the relative light emission intensities are compared. The voltage applied to the discharge lamp is 4 kV and the frequency is 10 kHz.

With each discharge lamp, the emission intensity against the gas pressure is measured. Each discharge lamp shows a maximum peak value of emission intensity at different gas pressures. The peak of the light emission intensity is regarded as the case of the maximum light emission efficiency, and the relationship between the opening diameter of the discharge site of each discharge lamp and the gas pressure giving the maximum light emission efficiency is obtained. The correspondence relationship between the gas pressure giving the maximum efficiency and the opening diameter is (opening diameter, gas pressure) = (50 μm, 8 atm), (150 μm, 6 atm), (500 μm, 4 atm). From this correspondence, in order to obtain the relationship between the gas pressure and the opening diameter in other ranges, an approximate expression is obtained from the measured values of the gas pressure and the opening diameter. As a result, if y is a gas pressure (atmospheric pressure) and X is an opening diameter (mm),
y = -1.74ln (X) + 14.76
Is obtained. From this equation, a graph showing the relationship between the gas pressure giving the maximum luminous efficiency and the opening diameter is as shown in FIG. At the points of (0.9 mm, 1.0 atm) and (3.0 mm, 3.0 atm) in FIG. 2, the luminous efficiency is reduced by 20% to 30% from the luminous efficiency on the curve.

The relationship between the gas pressure that gives the maximum luminous efficiency and the opening diameter at 1 to 3 atmospheres safe in a flat lamp will be described. The gas pressure indicating the maximum luminous efficiency corresponds to an opening diameter of 3.0 mm for 1 atmosphere. An opening diameter of 0.9 mm corresponds to 3 atmospheres. Therefore, at 1 to 3 atmospheres, an aperture diameter of 3.0 mm to 0.9 mm is the optimum corresponding condition. Since the shape of the opening need not be a circle, the opening diameter with respect to the gas pressure is replaced with the opening area. Therefore, the relationship between the gas pressure giving the maximum luminous efficiency and the opening area is as shown in FIG. As apparent from FIG. 3, in 1 to 3 atm gas pressure, the opening area 7.1mm ² ~0.6mm ² correspond.

  Further, in the relationship between the gas pressure and the light emission intensity, as shown in FIG. 4, the light emission intensity rapidly decreases with a decrease in pressure around 1 atm. Further, as shown in FIG. 5, the temporal fluctuation of the emission intensity increases rapidly in a region lower than around 1 atm. These phenomena occur similarly in each discharge lamp.

From the above, considering the safety against the discharge lamp burst, the gas pressure of the two-dimensional array type dielectric barrier discharge lamp is set in the range of 1 to 3 atmospheres, and the opening diameter (opening area) is set to the pressure. A specific value corresponding to is good. Under these conditions, the two-dimensional array type dielectric barrier discharge lamp exhibits good luminous efficiency. Specifically, the combination of the pressure of the discharge gas and the opening area of the discharge opening is (1 atm, 0.6 mm ² ) to (3 atm, 7.1 mm ² ). In this intermediate pressure range, the equation y = −1.74ln (X) +14.76
Thus, the gas pressure y is obtained from the opening diameter X and set. It is difficult to set the gas pressure strictly. In practice, an error of about 10% is an allowable range, so it is sufficient to set it with normal accuracy.

  In the two-dimensional array type discharge lamp of the present invention, an MgO insulating film 1a is laminated only on the surface of the dielectric 2 (not shown) in order to further improve the luminous efficiency and extend the life. This is A type. As shown in FIG. 6, an MgO insulating film 1 a is laminated on the surface of the dielectric 2 and the surface of the first electrode 1. This is B type. In addition, as shown in FIG. 7, a ceramic film 1 b having a high melting point and an electrical insulation property is laminated between the insulating film 1 a and the first electrode 1. This is C type. The opening diameter of the first electrode 1 is 150 μm, the thickness of the dielectric 2 (mica) is 100 μm, and the thickness of the first electrode 1 and the second electrode 3 is 20 μm. The thickness of the MgO film, which is the insulating film 3a, is 10 μm, and the thickness of the ceramic insulating film 3b is 10 μm. The insulating film 1a may be aluminum nitride. The insulating film 1b may be silica glass.

  These discharge lamps are filled with 1 atmosphere of Ar gas to perform discharge. The voltage applied to the discharge lamp is 4 kV and its frequency is 10 kHz. The reference discharge lamp is a conventional two-dimensional array type discharge lamp in which no insulating film is laminated. This is D-type. In each discharge lamp, the luminous efficiency and the life until the illuminance reaches 80% of the initial illuminance are measured.

  FIG. 8 shows the luminous efficiency and life of each discharge lamp as relative values. In the D type in which no insulating film is laminated, both the illuminance and the lifetime are the worst. In comparison with discharge lamps in which an insulating film is laminated, the A type in which the MgO insulating film 1a is laminated only on the surface of the dielectric 2 is most advantageous in terms of illuminance, but is the worst in terms of lifetime. The C type in which a ceramic film 1b having a high melting point and an electrically high insulating property is laminated between the insulating film 1a and the first electrode 1 is most advantageous in terms of life but is worst in terms of illuminance. In any case, the insulating film 1a and the insulating film 1b are effective in improving illuminance and life. Optimum performance can be obtained by appropriately selecting the lamination mode of these insulating films in accordance with the use and purpose of use of the discharge lamp.

The discharge gas, Ne, Ar, Xe, Kr, to _{Cl 2, I 2, Br 2} , may be any of F _2, it may be a mixed gas thereof. The sealing method of the discharge vessel 5 and the sealing of the light extraction window to the discharge vessel 5 may be chemical bonding or mechanical sealing using an O-ring. Although this embodiment has been described as a discharge lamp, it can also be used as a discharge device other than a lamp application. In that case, the light extraction window of the discharge vessel may be unnecessary. For example, it can be used for ozone generation through a UV permeable pipe inside the discharge vessel. Further, the whole or a part of the discharge vessel can be used as a light emitting means using a phosphor.

As described above, in the embodiment of the present invention, excimer molecules are formed in a two-dimensional array type dielectric barrier discharge lamp by a discharge container having a light extraction window for extracting excimer light, and dielectric barrier discharge. A discharge gas filled in the discharge vessel, a first electrode provided with a number of discharge openings in direct contact with the discharge gas, a dielectric layer provided in contact with the first electrode, and a dielectric A second electrode disposed opposite to the first electrode through the body layer, and the combination of the pressure of the discharge gas and the opening area of the discharge opening is (1 atm, 0.6 mm ² ) to (3 atm) 7.1mm ² ), the discharge opening is covered with a MgO film, and a ceramic insulating film is laminated between the MgO film and the first electrode. Long lamp can be realized.

  The two-dimensional array type dielectric barrier discharge device of the present invention is optimal as an ozone generator. The two-dimensional array type dielectric barrier discharge lamp of the present invention is optimal as a light source for a semiconductor substrate exposure apparatus, a light source for a display, and a light source for an illumination apparatus.

Sectional drawing of the two-dimensional array type dielectric barrier discharge lamp in the Example of this invention Graph showing the relationship between opening diameter and gas pressure showing maximum luminous efficiency Graph showing the relationship between gas pressure and opening area showing maximum luminous efficiency Graph showing the relationship between gas pressure and emission intensity A graph showing the rate of temporal fluctuation of the emission intensity against the gas pressure Sectional drawing of the two-dimensional array type dielectric barrier discharge lamp (B type) in the Example of this invention Sectional drawing of the two-dimensional array type dielectric barrier discharge lamp (C type) in the Example of this invention Table showing relative values of illuminance and life for each insulation film stacking mode Sectional view and plan view of a conventional two-dimensional array type dielectric barrier discharge lamp

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 1st electrode 2 Dielectric material 3 2nd electrode 4 Discharge opening part 5 Discharge vessel 6 Discharge space A Excimer light emission E Power supply

Claims (6)

A discharge electrode, a discharge gas filled in the discharge vessel so that excimer molecules are formed by dielectric barrier discharge, and a first electrode provided with a number of discharge openings that directly contact the discharge gas A two-dimensional array type dielectric barrier discharge comprising: a dielectric layer provided in contact with the first electrode; and a second electrode disposed opposite the first electrode with the dielectric layer interposed therebetween In the apparatus, based on the correspondence relationship between the opening area of the discharge opening and the discharge gas pressure at which the maximum luminous efficiency is obtained, (gas pressure = 1 atm, opening area = 0.6 mm ² ) to (gas pressure = A two-dimensional array type dielectric barrier discharge device, wherein the pressure of the discharge gas is set to an optimum value corresponding to the opening area within a range of 3 atm and opening area = 7.1 mm ² ). The two-dimensional array type dielectric barrier discharge device according to claim 1, wherein the discharge opening is covered with an insulating film of MgO or aluminum nitride. 3. The two-dimensional array type dielectric barrier according to claim 2, wherein an electrically insulating film having a high melting point of ceramic or silica glass is laminated between the insulating film and the first electrode. Discharge device. A discharge vessel having a light extraction window for extracting excimer light, a discharge gas filled in the discharge vessel so that excimer molecules are formed by dielectric barrier discharge, and a direct contact with the discharge gas A first electrode provided with a large number of discharge openings; a dielectric layer provided in contact with the first electrode; a second electrode disposed opposite to the first electrode with the dielectric layer interposed therebetween; In the two-dimensional array type dielectric barrier discharge lamp provided with the above, based on the correspondence relationship between the opening area of the discharge opening and the pressure of the discharge gas that can obtain the maximum luminous efficiency (gas pressure = 1 atm, opening The pressure of the discharge gas is set to an optimum value corresponding to the opening area within a range of (area = 0.6 mm ² ) to (gas pressure = 3 atm, opening area = 7.1 mm ² ). Two-dimensional array type dielectric barrier discharge laser Pump. 5. The two-dimensional array type dielectric barrier discharge lamp according to claim 4, wherein the discharge opening is covered with an insulating film of MgO or aluminum nitride. 6. The two-dimensional array type dielectric barrier according to claim 5, wherein an electrically highly insulating film having a high melting point of ceramic or silica glass is laminated between the insulating film and the first electrode. Discharge lamp.

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