JP2005317555A - Excimer lamp and excimer irradiation device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a flat type excimer lamp and an excimer irradiation device capable of efficiently irradiating excimer light. <P>SOLUTION: This excimer lamp 1 is provided with a discharge vessel 2 in a thin box shape, a discharging filler gas 5 filled in the discharge vessel 2, and two electrodes 4, 6 disposed face to face on the outside of the discharge vessel so as to hold the discharge vessel 2 between them, and when a high frequency voltage is impressed between them, excimer light is irradiated to the outside by permeating an excimer irradiating surface which is either one of the two electrodes. Thereby, if a body to be irradiated is placed apart from the excimer irradiating surface by a fixed distance, excimer light with sufficient strength can be efficiently irradiated to the body to be irradiated. In addition, since the excimer light is irradiated from the excimer irradiating surface, all of the irradiated excimer light can be irradiated to the body to be irradiated, and irradiation efficiency is enhanced. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a flat excimer lamp and an excimer irradiation apparatus that irradiates excimer light by RF discharge.

  An excimer lamp is usually called a silent discharge lamp, and is one of discharge lamps used as an ultraviolet light source for photochemical reaction. The excimer lamp emits ultraviolet light having a single wavelength such as 172 nm, 193 nm, 222 nm, or 248 nm (hereinafter referred to as “excimer light”) depending on the type of the enclosed gas. Such excimer light is used for decomposing organic compounds based on the ability to generate excited oxygen atoms, OH radicals, and the like, and for other processes based on strong photon energy. For example, in the field of the semiconductor industry, it is applied to dry cleaning for decomposing organic compounds that contaminate silicon wafers and glass substrates, and is applied to surface activation processing and soft ashing of semiconductor materials. In addition, it is applied in various fields such as surface activation treatment of resin and metal materials in the fields of fluorescent light emission of plasma display panels, LCD processes, and materials.

Furthermore, ultraviolet rays are used in the field of environmental technology for ozone generation, purification of water and air pollution, and ultrapure water production processes. In particular, it is also applied to the decomposition of organic compounds such as trichlorethylene, tetrachloroethylene, dioxin, and PCB, which are problematic in environmental pollution. As a specific decomposition method, decomposition of an organic compound contained in air is performed by first irradiating oxygen in the air to excimer light (especially excimer light in a vacuum ultraviolet region of 200 nm or less is preferable) to change to ozone. Then, the ozone is further irradiated with excimer light to change into an excited oxygen atom having a very strong oxidizing power, and finally, the excited oxygen atom decomposes an organic compound in the air to emit volatile substances such as CO ₂ and H _2. This is performed in the process of generating O or the like. In addition, decomposition of an organic compound contained in water is performed by irradiating water or dissolved oxygen in a liquid with excimer light (especially excimer light in a vacuum ultraviolet region of 200 nm or less is preferable), and extremely reactive OH radicals or O It is carried out in the process of changing to a radical, and the OH radical or O radical breaks the organic compound contained in water by breaking the bond chain of the organic compound.

  An excimer lamp filled with xenon gas as an enclosed gas can generate excimer light having a wavelength of 172 nm, which is vacuum ultraviolet light. Since this excimer light having a wavelength of 172 nm can generate many excited oxygen atoms, OH radicals, and the like, it is possible to efficiently decompose an organic compound contained in air or water. In addition, since excimer light having a wavelength of 172 nm has strong photon energy, the bond chain of the organic compound can be directly broken and decomposed by this photon energy.

  FIG. 5 shows an example of a conventional tube-type excimer lamp 61. The excimer lamp 61 includes a tube-shaped discharge vessel 62, an external electrode 63 disposed on the outside thereof, and a quartz tube 64 for protecting the external electrode 63. Further, nitrogen gas 65 is purged in order to exclude air existing between the discharge vessel 63 and the quartz tube 64.

  In the above-described excimer lamp 61, the outer peripheral portion of the tube-shaped discharge vessel 62 serves as an irradiation surface of the excimer lamp 61 (hereinafter referred to as “excimer irradiation surface”), and thus the irradiated object is an article such as a silicon wafer. In this case, only a part of the excimer light radiated in all directions from the excimer irradiation surface was irradiated to the irradiated object.

  In addition, excimer light has poor permeability in air and water, and oxygen in the air or dissolved oxygen in water at a distance of about 8 mm or more from the excimer irradiation surface is converted into ozone, excited oxygen atoms, OH radicals or O radicals, respectively There is a problem that it cannot be changed sufficiently or that the irradiated object to be surface-modified cannot be irradiated with photon energy sufficiently.

  Specifically, when the irradiated object is water containing an organic compound, only the organic compound in the water that has passed over the vicinity of the excimer irradiation surface is decomposed, and the water that has passed away from the irradiation surface The organic compound could not be decomposed sufficiently.

  Therefore, in the conventional tube-type excimer lamp, there is a problem that most of the emitted excimer light cannot be used effectively, and the organic compound cannot be sufficiently decomposed or surface-modified. . Conventionally, with respect to such a problem, a reflection plate has been provided to improve the irradiation efficiency, but it has not been sufficient.

  In order to solve the above-described problems, the present invention provides a flat excimer lamp and an excimer irradiation apparatus capable of efficiently performing excimer light irradiation.

  The flat excimer lamp according to claim 1 is opposed to the outside of the discharge vessel in a shape sandwiching the discharge vessel, a discharge vessel having a thin box shape, a discharge gas filled in the discharge vessel, and the discharge vessel. Two electrodes arranged, and when a high frequency voltage is applied, excimer light is irradiated to the outside through either one of the two electrodes.

  According to the present invention, the excimer light is irradiated to the irradiated object from the large-area excimer irradiation surface forming one surface of the thin box-shaped discharge vessel. Therefore, by setting the object to be irradiated at a certain distance from the excimer irradiation surface, it is possible to efficiently irradiate the object with excimer light having sufficient intensity. Moreover, since the excimer light is irradiated from the excimer irradiation surface, the irradiated object can be irradiated with all of the emitted excimer light, and the irradiation efficiency is improved. In particular, by arranging the irradiated object so as to be irradiated in the vicinity of the excimer irradiation surface, the irradiated object can be irradiated with less excimer light. As a result, the irradiated object can be efficiently subjected to desired processing such as dry cleaning or surface modification processing of a silicon wafer, or decomposition processing of an organic compound in air or water. In the excimer lamp of the present invention, a high-frequency voltage of 1 to 20 MHz is applied between the installation electrode and the external electrode, so that excimer light of uniform intensity is irradiated from each part of the large-area excimer irradiation surface. As a result, the irradiated object can be irradiated with a large irradiation area.

  According to a second aspect of the present invention, in the flat excimer lamp according to the first aspect, the electrode that transmits the excimer light is a mesh electrode.

  According to this invention, the high frequency voltage is applied between the installation electrode so that the fluid itself acts as an external electrode. The excimer light irradiated from the excimer irradiation surface is directly irradiated to the fluid flowing on the excimer irradiation surface. As a result, when the organic compound is contained in the fluid, the organic compound is sufficiently decomposed.

  The mesh electrode does not hinder excimer light irradiation. Therefore, it is possible to efficiently irradiate the irradiated object with excimer light.

  The excimer irradiation apparatus according to claim 3 is disposed oppositely to the outside of the discharge vessel in a shape of sandwiching the discharge vessel with a thin box-shaped discharge vessel, a discharge gas filled in the discharge vessel, and the discharge vessel. A plurality of excimer lamps each having two electrodes arranged in a fixed direction, and the excimer irradiation surface is arranged at a fixed interval with respect to the irradiated object. In this case, the excimer light is irradiated to the outside through one of the two electrodes.

  According to the present invention, since a plurality of flat excimer lamps are continuously provided in a certain direction, it is possible to continuously irradiate the irradiated object with excimer light. In addition, since the excimer irradiation surface is arranged at a constant distance from the irradiated object, the irradiated object can be irradiated without much attenuation of the excimer light. As a result, the object to be irradiated is sufficiently irradiated with excimer light from the continuously disposed excimer irradiation surface, so that efficient surface modification processing and organic compound decomposition processing are performed.

  As described above, according to the excimer lamp of the present invention, the excimer light is irradiated to the irradiated object from the large-area excimer irradiation surface forming one surface of the thin box discharge vessel. Therefore, by setting the object to be irradiated at a certain distance from the excimer irradiation surface, it is possible to efficiently irradiate the object with excimer light having sufficient intensity. Moreover, since the excimer light is irradiated from the excimer irradiation surface, the irradiated object can be irradiated with all of the emitted excimer light, and the irradiation efficiency is improved. As a result, the irradiated object can be efficiently subjected to desired processing such as dry cleaning or surface modification processing of a silicon wafer, or decomposition processing of an organic compound in air or water.

  According to the excimer irradiation apparatus of the present invention, since a plurality of flat excimer lamps are continuously provided in a fixed direction, it is possible to continuously irradiate the irradiated object with excimer light. In addition, since the excimer irradiation surface is arranged at a constant distance from the irradiated object, the irradiated object can be irradiated without much attenuation of the excimer light. As a result, the object to be irradiated is sufficiently irradiated with excimer light from the continuously disposed excimer irradiation surface, so that efficient surface modification processing and organic compound decomposition processing are possible.

  First, an excimer lamp of the present invention will be described with reference to the drawings.

  FIG. 1 is a perspective view showing an example of an excimer lamp according to the present invention, and FIG. 2 is a sectional view thereof. The excimer lamp 1 includes a thin box-shaped discharge vessel 2 having a large area excimer irradiation surface 3, a discharge gas filled in the discharge vessel 2, and the surface of the discharge vessel 2 opposite to the excimer irradiation surface 3. And at least an installation electrode 4 disposed on the top. Excimer light is irradiated from the excimer irradiation surface 3 by applying a high frequency voltage 7 of 1 to 20 MHz between the installation electrode 4 and the external electrode 6 provided on the excimer irradiation surface 3.

  The discharge vessel 2 has a thin box shape having a large area excimer irradiation surface 3 and is made of a dielectric material having excellent light transmittance through which the generated excimer light is easily transmitted. Usually, quartz or synthetic quartz with excellent light transmittance in a thin box shape is used and processed into a thin box discharge vessel. Quartz or synthetic quartz having a thickness of about 1 to 2 mm is used. Although the magnitude | size of the discharge container 2 is not specifically limited, It is preferable to set it as a thin box-shaped container with a large excimer irradiation surface and small height. For example, a discharge vessel having a vertical and horizontal dimension of several tens of centimeters to several tens of centimeters and a height of about several centimeters is used.

  The discharge sealed gas 5 is filled in the discharge vessel 2, and excimer light having different wavelengths can be generated depending on the type of the sealed gas 5. Representative examples include 146 nm for krypton (Kr) gas, 172 nm for xenon (Xe) gas, 191 nm for KrI gas, 193 nm for ArF gas, 222 nm for KrCl gas, 248 nm for KrF gas, etc. , Excimer light having a certain wavelength can be generated. Therefore, excimer light according to the purpose can be generated by selecting the gas sealed in the discharge vessel 2. The pressure of the sealed gas 5 sealed in the discharge vessel 2 can be determined by appropriately setting conditions according to the type of gas for obtaining excimer light having a target wavelength and the desired amount of excimer emission. Usually, it is sealed at a pressure of about 10 to 60 KPa.

  The installation electrode 4 is disposed on the surface of the discharge vessel 2 opposite to the excimer irradiation surface 3. As the material of the installation electrode 4, stainless steel, aluminum, aluminum alloy, copper, copper oxide, or an alloy thereof, yttrium oxide, yttrium aluminum oxide, or the like is preferably used. In selecting the installation electrode 4, one that exhibits good metal conductivity and has a high discharge rate is preferably selected. The shape of the installation electrode 4 is not particularly limited, such as a plate shape or a mesh shape. In addition, the installation electrode 4 has the entire surface of the discharge vessel 2 opposite to the excimer irradiation surface 3 so that the excimer light is uniformly discharged at each part in the discharge vessel 2 and the irradiation distribution on the excimer irradiation surface becomes uniform. It is preferable that it is provided over.

  The external electrode 6 is disposed on the excimer irradiation surface 3, and a high frequency voltage 7 is applied between the external electrode 6 and the installation electrode 4. Therefore, a net-like electrode is usually used so as not to hinder excimer light irradiation, but the shape is not particularly limited. The material and selection of the external electrode 6 are the same as in the case of the installation electrode 4.

  When the object to be irradiated is water containing an organic compound, it is preferable to apply an electric field, that is, a high-frequency voltage, between the installation electrode 4 and water so that the water itself acts as an external electrode. As a method for applying an electric field to water, as shown in FIG. 3 described later, a high frequency voltage 7 is applied to the conductive channel 41 without providing an external electrode. As a result, an electric field (high frequency voltage) is loaded between the installation electrode 4 and water, the excimer lamp 1 is discharged, and excimer light is irradiated. At this time, when the excimer irradiation surface 3 is used as a part of the flow path 41, the water containing the organic compound is irradiated with all of the excimer light emitted from the excimer irradiation surface 3. In addition, as a constituent material of the flow path 41, a material having metal conductivity and excellent corrosion resistance against water containing an organic compound, such as stainless steel, can be preferably used.

  By applying a high frequency voltage of 1 to 20 MHz, silent discharge occurs in the discharge vessel 2, and uniform and sufficient excimer light is irradiated from the excimer irradiation surface 3. Since the excimer lamp 1 of the present invention is applied with a voltage particularly at a high frequency of 1 to 20 MHz, the light emission efficiency and the thermal efficiency can be improved. Therefore, power consumption can be reduced, which is economically preferable. A more preferable frequency of the high-frequency voltage is 2 to 4 MHz. The high frequency voltage at this time is preferably 1 to 3 kV. When the high-frequency voltage is less than 1 kV, uniform and sufficient discharge does not occur between the external electrode 6 and the installation electrode 4, and sufficient excimer light cannot be uniformly irradiated from the excimer irradiation surface 3. On the other hand, when the high frequency voltage exceeds 3 kV, the excimer irradiation amount is saturated, and sufficient light emission efficiency cannot be obtained with respect to the input power, and the power consumption increases, resulting in poor efficiency.

The high-frequency voltage is supplied from a high-frequency power source and is applied between the external electrode 6 and the installation electrode 4 at a frequency of 1 to 20 MHz. The high-frequency power supply receives power of 12 to 15 V (usually about 12 V) from a DC power supply, and outputs predetermined power obtained by frequency conversion to a predetermined frequency of 1 to 20 MHz. For example, in order to irradiate excimer light with an illuminance of 10 mW / cm ² from the excimer irradiation surface 3, a high frequency of 3.7 MHz is applied between the external electrode 6 and the installation electrode 4 with a power of 50 to 70 W. do it.

  The excimer lamp 1 having such a configuration can uniformly irradiate excimer light from a large area excimer irradiation surface. Therefore, many irradiated objects can be processed at a time. In addition, since excimer light is uniformly irradiated from each part of the excimer irradiation surface, it is possible to efficiently irradiate the irradiation object with uniform intensity of excimer light by setting the irradiation object at a certain distance from the excimer irradiation surface. it can.

  Next, the excimer irradiation apparatus of the present invention will be described. FIG. 3 is a schematic view showing an aspect of an excimer irradiation apparatus 40 according to the present invention in which a plurality of excimer lamps 1 are continuously arranged in a certain direction. The excimer irradiation apparatus 40 of the present invention is configured such that a plurality of the excimer lamps 1 described above are connected in a fixed direction, and the excimer irradiation surface 3 is at a fixed distance from the irradiated object 41. As shown in FIG. 3 or FIG. 4, the excimer irradiation surface 3 is preferably provided so as to face a certain direction. As shown in FIG. 3, the excimer lamps 1 are arranged in such a manner that the excimer lamps 1 are connected in the longitudinal direction so that the irradiated object is irradiated from the excimer irradiation surface 3 of each excimer lamp 1. Alternatively, as shown in FIG. 4, the excimer lamps 1 can be arranged in the width direction so as to irradiate a large number of irradiated objects at once. As described above, the excimer lamp 1 of the present invention is irradiated with excimer light with a uniform intensity from the excimer irradiation surface 3, so that the irradiated object can be continuously processed over a wide area.

  In addition, since the irradiated object passes within a certain distance from the excimer irradiation surface 3, the irradiated object is irradiated with a large area of excimer light with little attenuation, and efficient surface modification treatment or decomposition of organic compounds. Processing is performed. Excimer light cannot be said to be excellent in permeability in air or water, so if it is about 8 mm or more away from the excimer irradiation surface 3, the excimer light gradually attenuates to obtain a sufficient excimer light effect. It may not be possible. Therefore, it is preferable that the irradiated object can be irradiated within 8 mm from the excimer irradiation surface. When the object to be irradiated is air or water, by setting the flow path within 8 mm from the excimer irradiation surface, it is possible to irradiate all the objects to be irradiated with excimer light having sufficient intensity. . However, such a distance is determined by the relationship between the excimer light irradiation intensity, the irradiation time, and the degree of treatment of the irradiated object. Good.

  Finally, the decomposition method of the organic compound of the present invention will be described. The organic compound decomposition method of the present invention is performed by using the excimer lamp 1 or the excimer irradiation apparatus 40 described above. As shown in FIG. 3, air or water containing an organic compound passes through a channel provided to flow in a certain direction. Since a plurality of excimer lamps are connected to the flow path, air and water flowing on the excimer irradiation surface are continuously irradiated with excimer light. As a result, the organic compound contained in the air or water is efficiently decomposed by receiving excimer light while sequentially flowing on the excimer irradiation surface. When the fluid is air containing an organic compound, excited oxygen atoms are generated in the air by irradiation with excimer light, and when the fluid is water containing an organic compound, OH radicals are generated in the water by irradiation with excimer light. And O radicals are generated. The generation of such radical species is caused by the chemical reaction between water molecules and dissolved oxygen, resulting in hydrogen peroxide water, etc., and then the reaction of excimer light and radical species with this hydrogen peroxide solution, thereby producing OH radicals and O radicals. Is easily generated. Since these excited oxygen atoms and each radical species are extremely reactive, the intermolecular bond of the organic compound contained therein is broken, and the excited oxygen atoms and radical species react with the broken portion and decompose. Is done. In particular, the decomposition reaction can be performed more efficiently by irradiating excimer light of 200 nm or less in the vacuum ultraviolet region. For example, when excimer light having a wavelength of 172 nm is irradiated to a liquid containing 1,1,1-trichloroethane, the bonds of C—C, C—H, and C—Cl in 1,1,1-trichloroethane are cleaved. Then, radical species react and decompose into carbon dioxide, carbon monoxide, water, hydrogen chloride, and chlorine. Since vacuum ultraviolet rays having a wavelength of 200 nm or less, for example, excimer light having a wavelength of 172 nm, can generate more radical species in the organic compound, the decomposition reaction of the organic compound easily occurs.

  Among organic compounds, particularly, organic chlorine compounds often pollute the air and water, and can be easily and efficiently decomposed by the organic compound decomposition method of the present invention. Examples of the organic compound include chlorofluorocarbon, dioxin, PCB, trichloroethylene, tetrachloroethylene, dichloromethane, carbon tetrachloride, 1,2-dichloroethane, 1,1-dichloroethane, cis-1,2-dichloroethane, 1,1,1-trichloroethane, 1, , 3-dichloropropene and the like, or a mixture thereof. These are all chlorine compounds, but can also be applied to organic halides containing other halogen elements, such as compounds containing fluorine and bromine.

  Since the fluid flows on the excimer irradiation surface, even if it is slightly dirty water, accumulation of impurities or the like does not occur on the excimer irradiation surface, and a relatively clean excimer irradiation surface can be maintained. Therefore, it will be excellent in maintenance and irradiation efficiency.

It is a perspective view which shows an example of the excimer lamp of this invention. It is a cross-sectional view of the excimer lamp of FIG. It is the schematic which shows the aspect of the excimer irradiation apparatus of this invention formed by connecting a plurality of excimer lamps in a fixed direction (longitudinal direction). It is the schematic which shows an example of the aspect with which the excimer lamp was continuously arranged in the width direction. It is sectional drawing which shows the conventional excimer lamp.

Explanation of symbols

1: Excimer lamp 2: Discharge vessel 3: Excimer irradiation surface 4: Installation electrode 5: Filled gas 6: External electrode 7: High-frequency voltage 40: Excimer irradiation device 41: Flow path

Claims (3)

A thin box-shaped discharge vessel;
A discharge gas filled in the discharge vessel;
Two electrodes opposed to the outside of the discharge vessel in a form sandwiching the discharge vessel,
An excimer lamp characterized in that, when a high-frequency voltage is applied, excimer light is irradiated to the outside through one of the two electrodes.   2. The excimer lamp according to claim 1, wherein the electrode that transmits the excimer light is a mesh electrode. An excimer lamp comprising a thin box-shaped discharge vessel, a discharge sealing gas filled in the discharge vessel, and two electrodes disposed opposite to the outside of the discharge vessel so as to sandwich the discharge vessel, A plurality of excimer irradiation devices arranged in a fixed direction, and the excimer irradiation surface is arranged at a fixed interval with respect to the irradiated object,
An excimer irradiation apparatus characterized in that, when a high-frequency voltage is applied, excimer light is irradiated to the outside through one of the two electrodes.

Images