JP2016149188A - Excimer lamp - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a structure which does not cause cracking of an inner tube due to ultraviolet light distortion, in an excimer lamp having a light permeable outer tube, and an inner tube to flow a cooling medium, where a discharge space formed between the outer tube and inner tube is filled with discharging gas for forming excimer molecules, an outer electrode is provided on the outer surface of the outer tube, and an inner electrode is provided on the inner surface of the inner tube.SOLUTION: The outer tube is made of silica glass, the inner tube is made of ceramic, and the outer and inner tubes are bonded and sealed by a low melting point metal using a cap member.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a double tube type water-cooled excimer lamp, and more particularly to an excimer lamp including an outer tube serving as a discharge tube and an inner tube serving as a water-cooled tube.

Conventionally, excimer lamps are frequently used to perform a cleaning process or an oxide film forming process for irradiating a target object with vacuum ultraviolet light having a wavelength of 200 nm or less. Recently, such processing technology tends to increase the input power to the excimer lamp in order to increase efficiency and speed. In such a high input excimer lamp, a cooling means is employed in order to prevent a decrease in ultraviolet transmittance due to a high temperature.
For example, Japanese Patent Laid-Open No. 2002-93377 (Patent Document 1) discloses a method of cooling a lamp by adopting a double tube type, using an outer tube as a discharge tube, and flowing cooling water into the inner tube. .
The structure is shown in FIG. 4, and the excimer lamp 20 has a double tube structure composed of an outer tube 21 and an inner tube 22 both made of quartz glass, and between the outer tube 21 and the inner tube 22. These spaces form a discharge space S. An outer electrode 23 is provided on the outer surface of the outer tube 21, and an inner electrode 24 is provided on the inner surface of the inner tube 22.

The discharge space S is filled with a discharge gas such as xenon gas, and an ultraviolet reflecting film 25 is formed on the outer surface of the inner tube 22 on the light emission space side, and is generated in the light emission space S. Ultraviolet rays are prevented from being irradiated to the inner tube 22.
Cooling water W is allowed to flow in the inner tube 22, and the discharge gas is cooled along with the cooling of the inner tube 22. Thus, it is intended to improve the lamp output by improving the production efficiency of excimer molecules and improving the ultraviolet transmittance by lowering the arc tube temperature.

By the way, in the excimer lamp based on the above prior art, the ultraviolet reflection film 25 is used to suppress the irradiation of the ultraviolet rays to the inner tube 22 to prevent the deterioration of the ultraviolet rays. It is difficult to form the ultraviolet reflection film 25 up to the junction with the outer tube 21 over the entire length in the length direction of the inner tube 22.
Furthermore, as shown in FIG. 5, the ultraviolet light that has entered the glass of the outer tube 21 from the discharge space S travels from the glass of the outer tube 21 through the side surface 21 a of the outer tube 21 by the fiber effect. Thus, it reaches the joint A between the outer tube 21 and the inner tube 22.
There is a problem in that ultraviolet distortion accumulates at the joint A and cracks occur at this portion. Since the inner tube 22 made of quartz glass is directly cooled by the cooling water, ultraviolet rays having a shorter wavelength can be transmitted, and the influence of accumulation of ultraviolet distortion is more serious.

JP 2002-93377 A

  In view of the above-described problems of the prior art, the present invention has an optically transparent outer tube and an inner tube through which a cooling medium flows, and an excimer is formed in a discharge space formed between the outer tube and the inner tube. In an excimer lamp that is filled with a discharge gas that forms molecules, and an outer electrode is provided on the outer surface of the outer tube, and an inner electrode is provided on the inner surface of the inner tube, the inner tube to be cooled is subjected to ultraviolet distortion. It is an object of the present invention to provide an excimer lamp structure that prevents the occurrence of cracks without occurring.

In order to solve the above problems, the present invention is characterized in that the outer tube is made of quartz glass and the inner tube is made of ceramic.
The outer tube and the inner tube are joined by a cap member that seals the open end of the outer tube, and the cap member, the outer tube, and the inner tube are sealed with a low melting point metal. It is characterized by being.
The low melting point metal is indium, tin, lead, bismuth, or an alloy thereof.
The cap member is made of metal, and an exhaust pipe is attached to the cap member.

According to the present invention, the outer tube that emits ultraviolet rays is made of quartz glass, and the inner tube through which the cooling medium flows is made of ceramic. Therefore, the ceramic inner tube has a large binding energy, and therefore receives ultraviolet rays from the discharge space. Also, there is an effect that no ultraviolet distortion occurs and no cracks are generated.
For this reason, there is also an advantage that the troublesome and complicated work of forming an ultraviolet reflecting film for protecting the inner tube can be omitted, and the work can be simplified.
Furthermore, since the outer tube and the inner tube are sealed by the cap member, there is an advantage that a difficult work process of directly sealing the outer tube to the inner tube can be omitted.

Sectional drawing of the excimer lamp of this invention. Sectional drawing of the other Example of this invention. The manufacturing process figure of the excimer lamp of this invention. Sectional drawing of a prior art. Explanatory sectional drawing of the malfunction of a prior art.

FIG. 1 is a cross-sectional view of an excimer lamp 1 according to the present invention. The excimer lamp 1 has a double tube structure including an outer tube 2 and an inner tube 3, and is formed between the outer tube 2 and the inner tube 3. The discharge space S is a discharge space S, and the discharge space S is filled with a discharge gas such as xenon gas that forms excimer molecules.
The outer tube 2 is made of quartz glass and is UV transmissive, and an outer electrode 4 is provided on the outer surface thereof. Since the outer electrode 4 extracts ultraviolet rays to the outside, the outer electrode 4 is made light transmissive such as mesh or coil.
On the other hand, the inner tube 3 is made of ceramic and does not have to be light transmissive because it is not necessary to extract ultraviolet rays to the outside. An inner electrode 5 is provided on the inner surface of the inner tube. In this embodiment, the inner electrode 5 is shown in the form of a coil. However, the present invention is not limited to this, and an arbitrary shape such as a cylindrical shape may be used.
Examples of the ceramic material constituting the inner tube 3 include alumina, sapphire, and zirconia.

In the embodiment of FIG. 1, both ends of the inner tube 3 are open, and a cooling medium W is caused to flow inside the inner tube 3 to cool the inner tube 3 and discharge gas in the discharge space S. Is cooling.
Similarly, both ends of the outer tube 2 are open, and both open ends are sealed with cap members 6 and 7. The cap members 6 and 7 are connected to the outer tube 2 and the inner tube 3 with a low melting point metal. It is joined and sealed by. The cap members 6 and 7 are made of a metal such as copper or a ceramic such as alumina, and the low melting point metal used for sealing is indium, tin, lead, bismuth, or an alloy thereof.
When the cap members 6 and 7 are made of metal, the exhaust pipe 8 can be provided on any one of the cap members 7 at both ends. The exhaust pipe 8 is made of, for example, copper, and is attached to the metal cap member 7 by brazing. Exhaust gas is discharged from the discharge space S through the exhaust pipe 8 and then filled with a discharge gas such as xenon gas. After filling with the discharge gas, the discharge space S is sealed by appropriate means such as crushing.

FIG. 2 shows an excimer lamp in which the outer tube 2 and the inner tube 3 are opened only at one end.
In this case, the outer tube 2 and the inner tube 3 are joined and fused together by a cap member 6 that closes the open end of the outer tube 2, and when the cap member 6 is made of metal, the cap member 6 The exhaust pipe 8 can be provided in the same manner as in the above embodiment.
Further, since the inner tube 3 is also opened at only one end portion, the cooling medium is introduced from the open end portion of the inner tube 3 and is similarly led out from the open end portion.
In order to make the flow of the cooling medium smooth in this embodiment, a tubular body having an open end is inserted concentrically into the inner tube 3, and the cooling medium is inserted into the inner tube 3 from this tubular body. It may be introduced and led out through an annular space between the tubular body and the inner tube 3. In this case, the flow of the cooling medium may be reversed, and may be introduced from the annular space and led out from the tubular body.

  Such an excimer lamp having the outer tube 2 and the inner tube 3 sealed on one end side can be used as a so-called head-on type in which light is extracted using the sealed one end portion of the outer tube 2 as a light extraction window. Further, similarly to the embodiment shown in FIG. 1, light may be extracted from the peripheral side surface of the outer tube 2.

An example of a method for joining and sealing the cap members 6 and 7 to the outer tube 2 and the inner tube 3 will be described with reference to FIG.
The outer peripheral surface 2a of the end portion of the outer tube 2 and the outer peripheral surface 3a of the penetrating portion of the inner tube 3 that penetrates the cap member 6 are previously subjected to metallization treatment with indium, for example.
As shown in FIG. 3A, the lamp is erected in a state where a low melting point metal 10 such as indium is accommodated in the cap member 6. This low melting point metal melts at about 200 to 300 ° C., and other than the above-mentioned indium, tin, lead, bismuth and the like are used. When heated in an inert gas atmosphere in this state, the low melting point metal 10 melts on the cap member 6 inside the discharge space S as shown in FIG.
As shown in FIG. 3C, the molten metal penetrates into the gap between the outer tube 2 and the cap member 6 and the gap between the inner tube 3 and the cap member 6 by capillary action, and solidifies between them when cooled. Then, the cap member 6, the outer tube 2 and the inner tube 3 are joined and sealed. At this time, the outer peripheral surface 2a of the end portion of the outer tube 2 and the outer peripheral surface 3a of the penetrating portion of the inner tube 3 have been subjected to metallization treatment, so that they are well compatible with molten metal and have a strong bond with the cap member 6. It will be something.

An example of the excimer lamp of the present invention is described as follows.
Outer tube 2: Outer diameter 40 mm, inner diameter 38 mm, total length 400 mm Synthetic quartz glass inner tube 3: Outer diameter 16 mm, inner diameter 14 mm, total length 500 mm made of alumina The end of inner tube 3 is filled with a cooling medium (pure water). A joint that connects to the pipe to be supplied is provided.
A net-like outer electrode 4 is provided on the outer surface of the outer tube 2. An inner electrode 5 is provided on the inner surface of the inner tube 3 facing it. The outer electrode 4 and the inner electrode 5 have a length of 330 mm in the longitudinal direction, which is the discharge length.
The cap members 6 and 7 were made of copper and joined and sealed to the outer tube 2 and the inner tube 3 with indium. The condition is heating to 200 ° C. in an inert gas atmosphere. A copper exhaust pipe 8 is brazed to the cap member 7.
As a discharge gas for forming excimer molecules, xenon gas is sealed at 80 kPa (600 Torr). The sealing pressure is in the range of about 53 to 101 kPa (400 to 760 Torr).

This lamp was connected to a high frequency power source and lit at a lamp input of 660 W at 6 kV and 110 kHz. When the lamp was lit, pure water was passed through the inner tube 3 as a cooling medium to cool the lamp.
Under these conditions, it was possible to light up without any cracks up to 1000 hours without any problem.

As described above, in the excimer lamp of the present invention, the outer tube for taking out the ultraviolet rays is made of quartz glass, and the inner tube through which the cooling medium flows is made of ceramic. Occurrence can be prevented, and early lighting does not occur.
Moreover, the trouble of forming an ultraviolet reflecting film for protecting the inner tube can be omitted.
Since the metal or ceramic cap member is used for joining the outer tube and the inner tube, the processing accuracy is improved, and the discharge gap between the outer electrode and the inner electrode can be manufactured with high accuracy.
Further, the exhaust pipe can be easily attached by making the cap member metal.

DESCRIPTION OF SYMBOLS 1 Excimer lamp 2 Outer tube 3 Inner tube 4 Outer electrode 5 Inner electrode 6,7 Cap member 8 Exhaust tube 10 Low melting point metal S Discharge space W Cooling medium

Claims (4)

A light transmissive outer tube and an inner tube through which a cooling medium flows;
A discharge gas that forms excimer molecules is filled in a discharge space formed between the outer tube and the inner tube,
In an excimer lamp having an outer electrode on the outer surface of the outer tube and an inner electrode on the inner surface of the inner tube,
An excimer lamp characterized in that the outer tube is made of quartz glass and the inner tube is made of ceramic.   The outer tube and the inner tube are joined by a cap member that seals the open end of the outer tube, and the cap member, the outer tube, and the inner tube are sealed with a low-melting metal. The excimer lamp according to claim 1.   The excimer lamp according to claim 2, wherein the low melting point metal is indium, tin, lead, bismuth, or an alloy thereof. The excimer lamp according to claim 2, wherein the cap member is made of metal, and an exhaust pipe is attached to the cap member.

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