Excimer lamp

Abstract

To simplify a manufacturing method of an excimer lamp and improve the mechanical strength of a sealing portion between the inner and outer tubes of the excimer lamp.SOLUTION: An excimer lamp according to the present invention includes an arc tube that has a double tube structure with an inner tube and an outer tube having closed distal ends, and in which a discharge space between the inner tube and the outer tube is filled with discharge gas, an internal electrode is arranged in the inner tube, an external electrode is arranged so as to partially cover the circumferential outer peripheral surface of the outer tube, and the ends of the outer tube and the inner tube in the direction opposite to the distal ends thereof are integrated and hermetically sealed.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to an excimer lamp.

Background Art

[0002] An excimer lamp is a discharge lamp that emits light from excimers formed by rare gas atoms or rare gas atoms and halogen atoms, taking advantage of the characteristic of a large number of short-time discharges in dielectric barrier discharge. Dielectric barrier discharge generates a discharge phenomenon by applying a high-frequency high voltage of several tens of Hz to several MHz between two electrodes sandwiching a dielectric. Currently, this excimer lamp is widely used mainly for pre-cleaning in wet processes such as LED manufacturing processes and semiconductor manufacturing processes, and pre-cleaning in film formation processes.

[0003] The excimer lamp according to the present invention specifically relates to an excimer lamp having a double tube structure of an inner tube and an outer tube, and at least one type of rare gas, halogen element, or a mixed gas thereof is enclosed in a discharge space between the inner tube and the outer tube. There are the following two related prior art documents.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

[0005] The content disclosed in Patent Document 1 is that in a discharge lamp which is an excimer lamp, a foil electrode is arranged along the tube axis inside the discharge tube. Also, the foil electrode is coated with a dielectric. On the other hand, an external electrode having a polarity different from that of the foil electrode is formed in a knife-edge shape that becomes thinner toward the edge.

[0006] Patent Document 2 discloses an excimer lamp that prevents damage to the inner tube due to the difference in thermal expansion coefficients between the inner electrode and the inner tube. The excimer lamp comprises a discharge tube made of a dielectric material with a discharge gas sealed in the discharge space, having a bottomed cylindrical inner tube and an outer tube having a sealed discharge space between the inner tube; an outer electrode disposed on the outer peripheral surface side of the outer tube of the discharge tube; and a rod-shaped inner electrode inserted into the inner tube. In this excimer lamp, a buffer space is formed between the inner peripheral surface of the inner tube and the outer peripheral surface of the inner electrode, with a cross-sectional area that suppresses the stress exerted by the inner electrode on the inner tube when the inner electrode expands due to dielectric barrier discharge, and that ensures dielectric barrier discharge in the discharge space, taking into account the size of the discharge space and the magnitude of the discharge voltage. [Overview of the project] [Problems that the invention aims to solve]

[0007] The excimer lamps disclosed in these prior art documents require a stepped seal between the inner tube and the metal electrode when sealing the ends of the lamp, which complicates the lamp manufacturing process. Furthermore, in the case of long lamps, there is a concern that the seal may become fragile as the mass of the inner tube and internal electrode increases.

[0008] Therefore, the present invention aims to simplify the lamp manufacturing method. Similarly, the present invention aims to improve the mechanical strength of the sealing portion between the inner and outer tubes of a lamp.

[0009] Comparing the aforementioned Patent Document 1 with the present invention, the present invention has the same double-tube structure, and the internal electrodes are foil-shaped electrodes, but they are not knife-edge shaped. In Patent Document 1, the internal electrodes are made knife-edge shaped to cause electric field concentration at the thin electrode edges, increasing the electric field strength and improving ignition start performance. However, the foil-shaped electrodes of the present invention have a uniform thickness, and the desired ignition start performance is ensured without the need to adopt a knife-edge shape.

[0010] Comparing the aforementioned Patent Document 2 with the present invention, in the present invention, the internal electrode and the inner tube are completely fused together, so there is no buffer space. Even without providing a buffer space, the desired lifespan is ensured, rather than being shortened. However, the present invention is not limited to the fused sealing structure of the internal electrode and the inner tube. [Means for solving the problem]

[0011] The excimer lamp according to the present invention has a double-tube structure on one side, comprising an inner tube and an outer tube, each having a closed tip, and a discharge tube in which a discharge gas is sealed in the discharge space between the inner tube and the outer tube. An internal electrode is arranged in the inner tube, and an external electrode is arranged so as to partially cover the circumferential outer surface of the outer tube, and the ends of the outer tube and the inner tube opposite to the tip are integrated and hermetically sealed.

[0012] Furthermore, in the excimer lamp described above, the external electrode may be formed from a plate-shaped or block-shaped metal made of aluminum or SUS, and the external electrode may function as a reflector that reflects light from the discharge tube.

[0013] Furthermore, in the excimer lamp described above, the external electrodes may be arranged over a range of at least half the circumference of the outer tube.

[0014] Furthermore, in the excimer lamp described above, the external electrode may extend longer in the axial direction than the internal electrode.

[0015] Furthermore, in the excimer lamp described above, the internal electrode may be a foil-shaped metal and may be fused to the inner tube.

[0016] Furthermore, the method for manufacturing an excimer lamp according to the present invention, on the one hand, has a double tube structure of an inner tube and an outer tube each having a closed tip portion, and a discharge gas is enclosed in a discharge space between the inner tube and the outer tube. A method for manufacturing an excimer lamp, comprising arranging an internal electrode in the inner tube, inserting the inner tube into the outer tube, integrally sealing and airtight sealing the end portion opposite to the tip portion, and enclosing and airtight sealing the discharge gas from an exhaust pipe formed at the tip portion of the outer tube, and arranging and fixing the outer tube inserted with the inner tube along a groove of an external electrode formed separately and independently in a plate shape or a block shape.

Effect of the Invention

[0017] According to the present invention, simplification of the lamp manufacturing method can be achieved, and further, improvement in the mechanical strength of the sealing portion between the inner tube and the outer tube can be achieved.

Brief Description of the Drawings

[0018] [Figure 1] FIG. 1 is a diagram for explaining a light emitting tube (portion excluding the external electrode) of the excimer lamp according to the present embodiment. [Figure 2] FIG. 2 is a diagram for explaining the external electrode of the excimer lamp of FIG. 1. [Figure 3] FIG. 3 is a diagram for explaining the whole of the excimer lamp according to the present embodiment. [Figure 4] FIG. 4 is a diagram for explaining the manufacturing method of the excimer lamp according to the present embodiment. The left side of the figure shows the flow of the manufacturing process, and a schematic diagram of the excimer lamp in each process is shown on the right side of each process.

Embodiments for Carrying Out the Invention

[0019] Hereinafter, embodiments of the excimer lamp according to the present invention will be described with reference to the accompanying drawings. The same reference numerals are assigned to the same elements shown in the drawings, and duplicate explanations are omitted.

[0020] [Excimer Lamp] FIG. 1 is a diagram for explaining the arc tube of the excimer lamp according to the present embodiment, that is, the portion excluding the external electrodes. The arc tube 10 of the excimer lamp is formed in a double structure of an inner tube 1 and an outer tube 2, and the inner tube 1 and the outer tube 2 have a sealing structure 9 at the left end as viewed in the figure. An internal electrode 4 is disposed inside the inner tube 1. The internal electrode 4 is preferably a foil-shaped electrode.

[0021] The internal electrode 4 is connected to an external lead wire 8 via an electrode introduction portion 5, and a terminal 7 is attached to the tip thereof. The internal space 3 formed by the inner tube 1 and the outer tube 2 is filled with a sealed gas.

[0022] The inner tube 1 is formed of a dielectric material having a high ultraviolet transmittance, for example, quartz. The internal electrode 4 is inserted inside the inner tube 1. The inner tube may be filled with a rare gas, or a part or all of the inner tube may be hermetically sealed. The "hermetic sealing" in this application document means, for example, disposing the internal electrode 4 of molybdenum foil inside the inner tube 1, and heating with a burner or high-frequency heating or the like in a negative pressure state to fix the inner tube 1 and the internal electrode 4 to a sealed state.

[0023] The outer tube 2 is a seal, and is similarly formed of a dielectric material having a high ultraviolet transmittance, for example, quartz. The internal space 3 is filled with a rare gas, a halogen, or a mixture thereof, for example, a mixed gas of krypton and chlorine. The foil-shaped internal electrode 4 has a uniform thickness and is formed of, for example, molybdenum foil (Mo foil). The electrode introduction portion 5 is formed of, for example, molybdenum foil (Mo foil). Further, the internal electrode 4 and the electrode introduction portion 5 may be integrally formed. The tip thereof is connected to an external lead wire 8 of an insulated metal wire.

[0024] Figure 2 illustrates the external electrode 12 of the excimer lamp 10 shown in Figure 1. Figure (A) shows the external electrode 12a in a front view, and (B) shows the external electrode 12b in a top view. The external electrode 12b in Figure 2 has a groove 12b-1 formed therein, and is shaped to house the excimer lamp's discharge tube 10 in the state shown in Figure 1. The external electrode 12 is a conductive material and is mainly made of metal. For example, the external electrode 12 is made of SUS or aluminum. Although the external electrode 12 in Figure 2 is shown as a block, it only needs to have a lamp-holding surface formed along the outer surface of the excimer lamp's discharge tube 10, and may be plate-shaped, for example.

[0025] When the excimer lamp is placed and fixed in the groove 12b-1 of the external electrode 12, the external electrode 12 is in contact with a part of the outer surface of the outer tube of the excimer lamp's discharge tube 10. That is, the external electrode 12 partially covers the circumferential outer surface of the excimer lamp's discharge tube 10. Excimer light passes through from the non-contact area (the uncovered direction). In the external electrode 12 shown in Figure 2, since the lamp is housed in the groove, the light is directed upward in a direction perpendicular to the plane of the paper in Figure 2.

[0026] The inner surface of the external electrode 12 at the contact point (the covered direction) functions as a reflector. Because the inner surface of the external electrode 12 has a high light reflectivity, the utilization rate of reflected light is improved. Generally, it is preferable that the external electrode 12 is arranged around the outer tube 2 of the discharge tube 10 over a range of at least 1 / 2 of the circumference.

[0027] Figure 3 is a diagram illustrating the overall structure of the excimer lamp according to this embodiment. Figure 3(A) is a front view showing the excimer lamp discharge tube 10 of Figure 1 housed in the groove of the external electrode 12 of Figure 2 and fixed at both ends. Figure 3(B) shows the left end cover 14a when viewed from the left, and (C) shows the right end cover 14b when viewed from the right, and (D) shows the external electrode 12 when viewed from above, and (E) shows the external electrode 12 when viewed from below. As can be seen in the diagram, the external electrode 12 extends longer in the lamp axial direction than the internal electrode 4.

[0028] [Excimer Lamp Manufacturing Method] Figure 4 illustrates an example of a manufacturing method for an excimer lamp according to this embodiment. The left side of Figure 4 shows the flow of the manufacturing process, and the right side of each process shows a schematic diagram of the excimer lamp in that process. For details of the schematic diagrams, please refer to Figures 1 and 3.

[0029] In step S1, the foil-shaped internal electrode 4 is inserted into the cylindrical inner tube 1. In step S2, part or all of the internal electrode 4 is fused to the inner tube 1. In step S3, the inner tube 1 is inserted into the outer tube 2, and a sealing structure 9 is formed at the left ends of both. The sealing structure 9 may be either a shrink seal or a pinch seal. In step S4, at least one noble gas, halogen element, or a mixture thereof is sealed into the internal space 3 from the tip 2a of the lamp's outer tube 2, and then the tip is hermetically sealed. In step S5, the excimer lamp discharge tube 10 is positioned along the groove 12a of the external electrode 12, and both ends of the excimer lamp discharge tube 10 are fixed to the external electrode 12.

[0030] [Advantages and Effects of This Embodiment] The excimer lamp and its manufacturing method according to this embodiment have the following advantages and effects.

[0031] (1) The manufacturing of lamps can be simplified. Conventional excimer lamps generally use a stepped seal to connect the inner and outer tubes. In this embodiment, the manufacturing of the lamp can be simplified by hermetically sealing the inner and outer tubes using either a shrink seal or a pinch seal.

[0032] (2) Even if the lamp is long, the mechanical strength between the inner and outer tubes can be strongly maintained. In this embodiment, since the space between the inner and outer tubes is directly sealed, the mechanical strength can be strongly maintained compared to the stepped seals of conventional lamps.

[0033] (3) It becomes possible to miniaturize the irradiation device equipped with the lamp.

[0034] (4) By using a single component to serve as both the external electrode and the reflector, the irradiation device can be miniaturized. In addition, because the external electrode has a high reflectivity, the utilization rate of reflected light is improved.

[0035] (5) Compared with prior art in which the external electrode is formed directly on the discharge tube, in this embodiment the discharge tube and the external electrode are formed separately and independently, and the discharge tube is assembled and fixed to the external electrode in the final step, making lamp maintenance and replacement easy. Furthermore, the manufacturing period can be shortened and the manufacturing process can be simplified. [Explanation of Symbols]

[0036] 1: Inner tube, 2: Outer tube, 3: Internal space, 4: Internal electrode, 5: Electrode introduction section, 8: External lead wire, 9: Sealing structure, 10: Excimer lamp discharge tube, 12, 12a, 12b: External electrode, 14a, 14b: Cover,

Claims

1. An excimer lamp comprising a discharge tube made of the same type of dielectric material with high ultraviolet transmittance, each having a double-tube structure of an inner tube and an outer tube with a closed tip, and a discharge gas sealed in the internal space between the inner tube and the outer tube, At the ends of the inner and outer tubes of the discharge tube opposite to the tip, an airtight sealing structure is formed, which integrates the inner and outer tubes using a shrink seal method or a pinch seal method. The inner tube of the aforementioned discharge tube has a foil-shaped internal electrode fused into it. Furthermore, the excimer lamp includes an external electrode made of block-shaped metal with a groove formed in the shape for housing the discharge tube. An excimer lamp in which the discharge tube is positioned and fixed in a groove of the external electrode, and the external electrode is positioned over at least half of the circumferential outer surface of the outer tube of the discharge tube and functions as a reflector that reflects light from the discharge tube.

2. In the excimer lamp according to claim 1, The excimer lamp wherein the external electrode is formed from a block of metal made of aluminum or stainless steel.

3. In the excimer lamp according to claim 1 or 2, An excimer lamp in which the external electrode extends longer in the direction of the lamp axis than the internal electrode.

4. A method for manufacturing an excimer lamp, which is made of the same type of dielectric material with high ultraviolet transmittance and has a double-tube structure of an inner tube and an outer tube, each having a closed tip, and a discharge gas is sealed in the internal space between the inner tube and the outer tube, A foil-shaped internal electrode is inserted into the inner tube and sealed by melting, The inner tube is inserted into the outer tube, and at the ends of the inner and outer tubes opposite to the tip, an airtight sealing structure is formed where the inner and outer tubes are integrated using a shrink seal method or a pinch seal method. The discharge gas is sealed and airtight through the exhaust pipe formed at the tip of the outer tube. A method for manufacturing an excimer lamp, comprising: positioning and fixing the outer tube into which the inner tube is inserted along grooves of a separately formed block-shaped metal external electrode, the external electrode being positioned over at least half of the circumferential outer surface of the outer tube of the discharge tube and functioning as a reflector that reflects light from the discharge tube.

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