JP3719753B2 - Gas laser device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a discharge excitation type gas laser device, and more particularly to prevention of abnormal discharge between a preionization electrode and a laser chamber inner wall.
[0002]
[Prior art]
Gas laser devices such as excimer laser devices excite molecules of laser gas (in the case of excimer laser devices, for example, a mixed gas of halogen gas F2 gas, rare gas Kr gas and buffer gas He gas) by discharge excitation or the like. The laser beam is oscillated. In the gas laser device, pre-ionization is performed before starting the main discharge in order to obtain a glow discharge in which the entire discharge space spreads uniformly during the above-described discharge, and electrons are dispersed in advance throughout the main discharge space. It is necessary to keep. In particular, in the case of an excimer laser device, since the lifetime of electrons in the halogen gas is short, it is necessary to generate as many electrons as possible immediately before the main discharge. Accordingly, in general gas laser apparatuses, those having a main discharge electrode for main discharge and a preionization electrode for preionization are often used.
[0003]
As a gas laser device provided with such a preionization electrode, for example, there is an excimer laser device proposed by Japanese Patent Application No. 4-328546. FIG. 3 shows the configuration of the proposed excimer laser device. Hereinafter, a conventional preliminary ionization electrode will be described with reference to FIG.
The laser chamber 1 is a discharge tube that discharges and excites laser gas sealed therein to oscillate laser light. A cross flow fan (hereinafter referred to as a fan) 2 for circulating the laser gas is provided in the laser chamber 1. It is arranged. A bellows 4 is disposed in the laser gas reflux path, and a laser gas flow path is formed between the bellows 4 and the inner wall of the laser chamber 1. In FIG. 3, the laser gas recirculation direction is an optical axis direction of the laser light, that is, a direction orthogonal to the direction perpendicular to the paper surface in the drawing.
[0004]
Further, main discharge electrodes 6 and 6a are provided opposite to each other in the laser gas reflux path. The discharge directions of the main discharge electrodes 6 and 6a are orthogonal to the laser gas recirculation direction and the laser optical axis direction, and a main discharge space 11 is formed between the main discharge electrodes 6 and 6a. One main discharge electrode 6 a of the main discharge electrodes 6, 6 a is supported by an outer wall of the laser chamber 1 and attached to an insulating member 13 that separates the inside and the outside of the laser chamber 1. The other main discharge electrode 6 is attached to and supported by an electrode support 5 attached to the inner wall of the laser chamber 1. The main discharge electrodes 6 and 6a have an elongated shape in the laser optical axis direction in order to cause main discharge space 11 to perform main discharge uniformly.
Further, in the vicinity of the main discharge space 11, preliminary ionization electrodes 8 and 8 a are arranged side by side in a direction perpendicular to the laser gas recirculation direction and the laser optical axis direction. The preliminary ionization electrodes 8 and 8a are respectively provided before and after the main discharge electrodes 6 and 6a in the laser gas recirculation direction. One of the preliminary ionization electrodes 8 and 8 a is attached to the inner wall of the laser chamber 1. The other preliminary ionization electrode 8 a penetrates the outer peripheral wall of the laser chamber 1 from the inside to the outside, and is attached to an insulating member 12 attached to the laser chamber 1.
[0005]
The main discharge electrode 6 and the preliminary ionization electrode 8 are electrically connected so as to have the same potential as the outer peripheral wall of the laser chamber 1. The other main discharge electrode 6 a is insulated from the laser chamber 1 by the insulating member 13, and is connected to a power supply line 14 outside the laser chamber 1. The other preliminary ionization electrode 8 a is insulated from the laser chamber 1 by the insulating member 12 and the current introduction terminal holder 16, and the power supply line 10 connected to the preliminary ionization electrode 8 a passes through the inside of the insulating member 12 and passes through the laser chamber 1. Led outside. And between the main discharge electrode 6 and the preionization electrode 8, and the main discharge electrode 6a and the preionization electrode 8a, the outer peripheral wall of the laser chamber 1 and the feed line 14 and the feed line 10 are connected from the excitation power source. The power line is connected. This excitation power supply supplies a high voltage and current of a predetermined magnitude between the main discharge electrodes 6 and 6a and between the preionization electrodes 8 and 8a. In the present embodiment, the excitation power supply 17 supplies power, the coil 18 that temporarily stores energy supplied from the power supply 17, and the energy stored in the coil 18 is absorbed and stored to generate a high voltage. However, the present invention is not limited to this.
[0006]
In such an excimer laser device, when high voltage energy is accumulated in the capacitors 19a and 19b from the power source 17 through the coil 18, arc discharge occurs between the preionization electrodes 8 and 8a, and the ultraviolet light energy at this time The laser gas in the main discharge space 11 is ionized due to (hereinafter referred to as preionization light energy), and a large amount of electrons are generated. The large amount of generated electrons facilitates glow discharge between the main discharge electrodes 6 and 6a. Next, when this glow discharge is generated in the main discharge space 11, the Kr gas is excited by the energy of fast electrons in the main discharge space 11, and the excited state Kr atoms react with F2 molecules to generate KrF excimers. Thus, the laser beam by the Kr F excimer oscillates.
[0007]
[Problems to be solved by the invention]
However, since the laser chamber 1 is generally made of a conductive metal such as aluminum, in the preliminary ionization electrodes 8 and 8a having the above-described configuration, the gap between the preliminary ionization electrode 8a and the laser chamber inner wall 9 is used. In some cases, arc discharge may occur. In this case, the preionization light energy is not released to the main discharge space 11. At this time, since the laser gas in the main discharge space 11 is not uniformly ionized, the main discharge becomes unstable. For this reason, since the amount of gas ionized for each discharge varies, there is a problem that the Kr F excimer is not uniformly generated and the laser beam output becomes unstable.
[0008]
The present invention has been made paying attention to the above problems, and reliably generates a preliminary discharge between the preliminary ionization electrodes, thereby eliminating variations in the amount of preliminary ionization light energy released into the main discharge space for each discharge. An object of the present invention is to provide a gas laser device that can perform the above-described operation.
[0009]
[Means, actions and effects for solving the problems]
In order to achieve the above object, the invention according to claim 1 is a discharge excitation type gas laser apparatus in which current introduction portions 8 and 8a for preionization are provided on a laser chamber inner wall 9,
The insulating member 22a for preventing discharge covering the surface of the inner wall 9 of the laser chamber in the vicinity of the current introduction parts 8 and 8a is provided.
[0010]
According to the first aspect of the present invention, since the surface of the laser chamber inner wall 9 in the vicinity of the pre-ionization current introduction portions 8 and 8a is covered with the discharge preventing insulating member, the current introduction portion and the laser chamber inner wall 9 There will be no discharge in between. Therefore, the preliminary discharge is surely generated between the preliminary ionization electrodes, and the preliminary ionization light energy is stably released to the main discharge space. Therefore, the amount of gas excited in the main discharge space does not vary every discharge, so that the laser light quantity at the time of laser light oscillation is stabilized. As a result, a stable laser output can be obtained.
[0011]
The invention according to claim 2 is the gas laser device according to claim 1,
The discharge preventing insulating member 22 a is configured to be positioned on the laser chamber inner wall 9 by inserting the protruding portion 22 b into a hole provided in the laser chamber inner wall 9.
[0012]
According to the second aspect of the present invention, the insulating member for preventing discharge according to the first aspect has a protruding portion inserted into a hole provided at a predetermined position of the inner wall of the laser chamber, and the protruding portion is inserted into the hole. By inserting the part, the insulating member for preventing discharge can be positioned easily and reliably. Therefore, it becomes easy to attach the insulating member, and the amount of variation in the amount of gas excited in the main discharge space for each discharge becomes smaller. Therefore, the laser light quantity at the time of laser light oscillation is further stabilized, and a stable laser output can be obtained.
[0013]
The invention according to claim 3 is the gas laser device according to claim 1,
The insulating member 22a for preventing discharge is configured to be mounted on the inner wall 9 of the laser chamber together with the components mounted on the inner wall 9 of the laser chamber.
[0014]
According to the third aspect of the invention, since the insulating member for preventing discharge according to the first aspect is mounted on the inner wall of the laser chamber together with a part mounted on the inner wall of the laser chamber, for example, the preionization electrode, the insulating member for preventing discharge As a result, mounting and positioning are easy, and assembling at the time of manufacture is improved. In addition, since the amount of variation in the amount of gas excited in the main discharge space for each discharge is reduced, the amount of laser light during laser light oscillation is stabilized. As a result, a stable laser output can be obtained.
[0015]
According to a fourth aspect of the present invention, there is provided the gas laser device according to the first aspect,
The discharge preventing insulating member 22a is formed by coating the surface of the inner wall 9 of the laser chamber.
[0016]
According to the invention described in claim 4, since the insulating member for preventing discharge according to claim 1 is coated on the surface of the inner wall 9 of the laser chamber, it is not necessary to attach the insulating member for preventing discharge during manufacturing. Work becomes easy. In addition, since the amount of variation in the amount of gas excited in the main discharge space for each discharge is reduced, the amount of laser light during laser light oscillation is stabilized. As a result, a stable laser output can be obtained.
[0017]
The invention according to claim 5 is the gas laser device according to claim 1,
The insulating member 22a for preventing discharge is configured to be affixed to the surface of the inner wall 9 of the laser chamber.
[0018]
According to the invention described in claim 5, since the discharge preventing insulating member according to claim 1 is affixed to the surface of the inner wall 9 of the laser chamber, the discharge preventing insulating member can be easily attached at the time of manufacture. Becomes easy. In addition, since the amount of variation in the amount of gas excited in the main discharge space for each discharge is reduced, the amount of laser light during laser light oscillation is stabilized. As a result, a stable laser output can be obtained.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a cross-sectional view showing a configuration in a laser chamber of a gas laser apparatus according to the present invention. In the figure, the same reference numerals are given to the same components as those in the prior art, and description thereof is omitted here. A heat exchanger 3 for cooling the laser gas heated by the discharge and refluxed by the fan 2 is disposed in the laser chamber 1. In FIG. 1, a laser gas recirculation direction 20 is a direction perpendicular to the optical axis direction of the laser light (in FIG. 1, the direction perpendicular to the paper surface).
[0020]
Further, in the vicinity of the main discharge space 11, preliminary ionization electrodes 8 and 8a, which are current introduction portions for preliminary ionization, are arranged side by side in a direction perpendicular to the laser gas recirculation direction 20 and the laser optical axis direction. ing. And the position of the preliminary discharge space of both the preliminary ionization electrodes 8 and 8a is set to the approximate center between the main discharge electrodes 6 and 6a.
[0021]
FIG. 2 shows an X view near the preliminary ionization electrode 8a of FIG. 1, and will be described below with reference to FIGS. The preliminary ionization electrode 8a is attached to the insulating member 12 together with the power supply line 10, and the insulating member 12 is inserted into an insulating member mounting hole 25 provided at a predetermined position on the inner wall 9 of the laser chamber and attached to the inner wall 9 of the laser chamber. Yes. In addition, an insulating member 22a for preventing discharge is provided on the inner wall 9 of the laser chamber in the vicinity of the preliminary ionization electrodes 8 and 8a, so that no discharge is generated between the preliminary ionization electrode 8a and the inner wall 9 of the laser chamber. Yes. In this embodiment, the insulating member 22a for preventing discharge has a protruding portion 22b that is inserted into the insulating member mounting hole 25 and has a hole into which the insulating member 12 is inserted, and insulates the protruding portion 22b. By inserting into the member mounting hole 25, the discharge preventing insulating member 22a is easily positioned.
Further, between the main discharge electrode 6 and the preionization electrode 8 and the main discharge electrode 6a and the preionization electrode 8a, there is a power supply line from the excitation power source (see FIG. 3) via the power supply line 10 and the power supply line 14. It is connected.
[0022]
Next, the operation of the discharge preventing insulating member 22a having the above-described configuration will be described.
The discharge preventing insulating member 22a is provided on the inner wall 9 of the laser chamber so as to cover the vicinity of the preliminary ionizing electrode 8a, and insulates the preliminary ionizing electrode 8a from the inner wall 9 of the laser chamber. Therefore, it is possible to prevent the discharge from occurring between the preionization electrode 8a and the inner wall 9 of the laser chamber, and it is possible to reliably cause the predischarge between the preionization electrodes 8 and 8a. As a result, the preionization light energy is reliably and uniformly released into the main discharge space 11, and the amount of the preionization light energy released into the main discharge space 11 does not vary from discharge to discharge. For this reason, since the amount of gas excited in the main discharge space 11 does not vary, the amount of laser light at the time of laser light oscillation is stabilized. As a result, a stable laser output can be obtained.
[0023]
Further, the discharge preventing insulating member 22a has a protruding portion 22b. After the protruding portion 22b is inserted into the insulating member mounting hole 25, the insulating member 12 is inserted into a hole inside the protruding portion 22b to insert a laser chamber. 1 is attached. As a result, the insulating member 22a for preventing discharge can be positioned reliably and easily, so that the workability at the time of assembling is improved and the variation in discharge is eliminated and the laser output is further stabilized.
[0024]
Note that the protruding portion 22b of the discharge preventing insulating member 22a is not the gist of the present invention and may be omitted. In this case, the discharge preventing insulating member 22a may be attached together by a component (such as the preionization electrode 8) attached to the inner wall 9 of the laser chamber. Further, as means for fixing the insulating member 22a for preventing discharge to the inner wall 9, it can be realized by pasting or coating with an adhesive or the like.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a configuration in a laser chamber of a gas laser apparatus according to the present invention.
FIG. 2 is a detailed view (X view in FIG. 1) of an insulating member 22a for preventing discharge according to an embodiment of the present invention.
FIG. 3 is a cross-sectional view showing a configuration in a laser chamber according to the prior art.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Laser chamber, 2 ... Fan, 3 ... Heat exchanger, 4 ... Bellows, 5 ... Electrode support body, 6 and 6a ... Main discharge electrode, 8 and 8a ... Preionization electrode, 9 ... Inner wall of laser chamber, 10 ... Supply Electric wire, 11 ... main discharge space, 12 ... insulating member, 13 ... insulating member, 14 ... feeder line, 16 ... current introduction terminal holder, 17 ... power supply, 18 ... coil, 19a, 19b ... capacitor, 20 ... laser gas recirculation direction, 22a ... Insulating member for preventing discharge, 22b ... Projecting portion, 25 ... Insulating member mounting hole.

Claims (2)

A laser chamber (1) ;
An insulating member (12) penetrating the laser chamber (1) ;
A feed line (10) passing through the insulating member (12) ;
A preionization electrode (8a) provided in contact with the feeder line (10) substantially parallel to the inner wall of the laser chamber (9) ,
An insulating member for preventing discharge (22a) provided around the power supply line (10) ,
The discharge preventing insulating member (22a) has a plate-like portion,
The gas laser device, wherein the plate-like portion is installed along the inner wall (9) of the laser chamber so as to cover the vicinity of the vicinity of the preliminary ionization electrode (8a) . A laser chamber (1) ;
An insulating member (12) penetrating the laser chamber (1) ;
A feed line (10) passing through the insulating member (12) ;
A preionization electrode (8a) provided in contact with the feeder line (10) substantially parallel to the inner wall of the laser chamber (9) ,
An insulating member for preventing discharge (22a) provided around the power supply line (10) ,
The discharge preventing insulating member (22a) has a plate-like portion,
The plate-like portion,
The projection of the plate-like portion on the inner wall (9) of the laser chamber includes the projection of the preliminary ionization electrode (8a) on the inner wall (9) of the laser chamber .
A gas laser device, which is installed along the inner wall (9) of the laser chamber .

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