JPH05235451A - Excimer laser device - Google Patents

Abstract

PURPOSE:To reduce the quantity of dust accumulated on the surface of a corona discharge electrode and on the inner surface of an inner dust-collecting electrode facing this, and to lighten the reduction of dust collection efficiency in long-time run and prolong a maintenance period for dust filters, by using a dust filter having dust-collecting electrodes of double-pipe structure. CONSTITUTION:Concerning to a dust filter 11, its dust-collecting electrodes have double-pipe structure composed of an inner cylindrical electrode 15 and an external cylindrical electrode 16, and a linear corona discharge electrode 17 is provided at its center. Besides, there are potential differencies between the corona discharge electrode 17 and the inner cylindrical electrode 15, and between the inner cylindrical electrode 15 and the external cylindrical electrode 16 respectively. Consequently, a part of dust entering the dust filter can be collected beforehand in the electric field space between the inner cylindrical electrode and the external cylindrical electrode, and a maintenance period for the dust filter can be prolonged.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a discharge excitation excimer laser device, and more particularly to an excimer laser device equipped with a dust filter for collecting fine particles in laser gas generated by discharge.

[0002]

2. Description of the Related Art Conventional excimer laser devices generally contain a mixed gas of a rare gas and a halogen gas as a laser gas in a container. Then, a preliminary ionization discharge is first performed inside, the laser gas is ionized by the generated ultraviolet rays, then the laser gas is excited by a high-voltage pulse discharge, and the generated light is extracted from an optical window provided in the container to realize laser oscillation. is doing.

As described above, since the excimer laser device uses a high-voltage pulse discharge, fine particles generated by the sputtering action of the electrode surface or the like become dust in the laser gas.
As a result, the laser output is reduced by drifting, scattering the laser light, or adhering to the surface of the optical window. In order to deal with this problem, an excimer laser device incorporating a dust collector called a "dust filter" has been proposed.

The dust filter used in this excimer laser device includes an electrostatic precipitator (Japanese Patent Laid-Open No. 58-1869).
No. 85) and a magnet dust collecting method (Japanese Utility Model Laid-Open No. 2-73753) are proposed, but the former is more practical and is also used in a commercially available excimer laser device. This electrostatic precipitator uses electrostatic force to charge fine particles in gas using corona discharge, and to apply electrostatic field to separate fine particles from gas by electrostatic force and collect them on the electrode surface. .

As described above, the conventional excimer laser device has a corona discharge electrode 1 for generating a corona discharge, as shown in FIG.
It has an electrostatic precipitating type dust filter composed of a cylindrical dust collecting electrode 3 having a laser gas inlet 2.

[0006]

As described above, the conventional excimer laser device uses the dust filter of the electrostatic precipitating system to prevent the reduction of the laser output, but the electrostatic precipitating system collects in principle. Dust is deposited on the surfaces of the corona discharge electrode 1 and the dust collecting electrode 3. Therefore, when the operation is continued for a long period of time, the corona discharge current is reduced, the dust collection efficiency is lowered, and finally the corona discharge is stopped. Therefore, it was necessary to regularly perform maintenance on the dust filter.

SUMMARY OF THE INVENTION An object of the present invention is to provide an excimer laser device which has been made in view of the above problems and which can extend the maintenance period of a dust filter.

[0008]

The invention according to claim 1 is
In an excimer laser device that generates a laser beam by performing a high-voltage pulse discharge in a mixed gas of a rare gas and a halogen gas, the dust collecting electrode of the dust filter has a double-tube structure consisting of an inner cylindrical electrode and an outer cylindrical electrode. Inside the laser tube, a means to generate a nearly uniform electric field between the inner and outer cylindrical electrodes of the dust collecting electrode, a means to generate a corona discharge between the inner cylindrical electrode and the wire electrode installed in the center And a means for guiding the laser gas containing fine particles to the electric field space between the inner cylindrical electrode and the outer cylindrical electrode, and a means for guiding the laser gas to the corona discharge space inside the inner cylindrical electrode tube. ..

According to a second aspect of the present invention, the electric field generating means and the corona discharge generating means are integrated into one by making the outer cylindrical electrode and the central line electrode have the same potential and providing a potential difference between the inner cylindrical electrode. It is configured to be covered by a power supply device.

[0010]

As described above, according to the present invention, the dust filter having the double-tube structure as the dust collecting electrode is used to prevent the laser output from being lowered. It is now possible to collect dust in the electric field space between the cylindrical dust collecting electrode and the outer cylindrical dust collecting electrode. Therefore, the amount of dust accumulated on the surface of the corona discharge electrode and the inner surface of the inner dust collecting electrode facing the surface of the corona discharge electrode can be reduced. As a result, the decrease in dust collection efficiency during long-term operation is reduced, and the maintenance period of the dust filter can be extended.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings. FIG. 1 is a sectional view of a laser tube portion of an excimer laser device according to an embodiment of the present invention. A dust filter 11 is installed on the side wall of the laser container 10. A fan 12 is arranged inside the laser container 10, and a main discharge electrode 13 and preliminary ionization electrodes 14 located on both sides of the main discharge electrode 13 are arranged on the upper side of the fan 12. ing.

In the excimer laser device constructed as described above, fine particles (dust) generated by discharge sputtering or the like in the main discharge electrode 13 and the preliminary ionization electrode 14.
However, normally, the fan 12 floats in the laser tube together with the laser gas circulating in the laser container 10, and a part thereof enters the dust filter 11 and is collected by electrostatic action. By the way, the dust generated in the laser container 10 may be charged by the discharge between the main discharge electrodes 13 and enter the dust filter 11. Therefore, even if an electric field is applied between the electrodes without corona discharge for charging, these charged dusts can be collected.

2 and 3 are a horizontal sectional view and a vertical sectional view of a dust filter used in the excimer laser device of the present invention. The dust filter 11 has a double tube structure in which the dust collecting electrode is composed of an inner cylindrical electrode 15 and an outer cylindrical electrode 16, and a linear corona discharge electrode 17 is installed at the center. The inner cylindrical electrode 15 and the outer cylindrical electrode 16 are provided with laser gas inlets 15A and 16A, respectively, and both sides of the inner cylindrical electrode 15 are supported by a glass material 18. In addition, there are potential differences between the corona discharge electrode 17 and the inner cylindrical electrode 15 and between the inner cylindrical electrode 15 and the outer cylindrical electrode 16, respectively. Therefore, an unequal electric field is created between the corona discharge electrode 17 and the inner cylindrical electrode 15, and corona discharge occurs.

On the other hand, the inner cylindrical electrode 15 and the outer cylindrical electrode 1
Since a substantially even electric field is generated between the electric field and the electric field 6, a corona discharge does not occur, and an electric field space in which spark discharge does not occur can be obtained by setting the applied voltage to an appropriate value. Therefore, the inner cylindrical electrode 15 and the outer cylindrical electrode 1
The charged dust that has entered the electric field space between 6 and 6 is collected at this point, and the remaining dust is charged by corona discharge inside the inner cylindrical electrode 15 and collected inside thereof. In FIG. 2, reference numeral 19 indicates a line of electric force.

Various methods are conceivable as means for generating a potential difference between the corona discharge electrode 17 and the inner cylindrical electrode 15 and between the inner cylindrical electrode 15 and the outer cylindrical electrode 16, for example, the inner cylindrical electrode 15 It is conceivable that a corona discharge electrode 17 and an outer cylindrical electrode 16 are installed by applying a square voltage only to. With this configuration,
This has the advantage that only one power supply device needs to generate the potential difference.

[0016]

As described above, according to the excimer laser device of the present invention, the dust collecting electrode of the dust filter used as a means for preventing the reduction of the laser output caused by the fine particles generated in the laser tube is used. By adopting a double tube structure composed of an inner cylindrical electrode and an outer cylindrical electrode, it is possible to collect a part of the dust entering the dust filter in the electric field space between the inner cylindrical electrode and the outer cylindrical electrode in advance. became. Therefore, the amount of dust accumulated on the surface of the corona discharge electrode and the inner surface of the inner cylindrical electrode facing the surface of the corona discharge electrode can be significantly reduced. As a result, it is possible to reduce the deterioration of the dust collection efficiency during long-term operation, and it is possible to significantly extend the maintenance period of the dust filter as compared with the conventional case, which is an excellent effect.

[Brief description of drawings]

FIG. 1 is a sectional view of a laser tube portion of an excimer laser device according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a dust filter used in the excimer laser device.

FIG. 3 is a vertical sectional view of the dust filter.

FIG. 4 is a cross-sectional view of a dust filter used in a conventional excimer laser device.

[Explanation of symbols]

 10 Laser Container 11 Dust Filter 15 Inner Cylindrical Electrode 16 Outer Cylindrical Electrode 17 Corona Discharge Electrode

Claims (2)

[Claims] 1. An excimer laser device for generating a laser beam by performing high-voltage pulse discharge in a mixed gas of a rare gas and a halogen gas, wherein a dust collecting electrode of a dust filter is a double electrode including an inner cylindrical electrode and an outer cylindrical electrode. With a tube structure, means for generating a substantially uniform electric field between the inner cylindrical electrode and the outer cylindrical electrode of the dust collecting electrode, and means for generating a corona discharge between the inner cylindrical electrode and the line electrode installed in the central portion. A means for guiding a laser gas containing fine particles generated in the laser tube to an electric field space between the inner cylindrical electrode and the outer cylindrical electrode, and a means for guiding the laser gas to a corona discharge space inside the inner cylindrical electrode tube. An excimer laser device. 2. The electric field generating means and the corona discharge generating means are integrated into one power supply device by making the outer cylindrical electrode and the central line electrode have the same electric potential and providing a potential difference between the outer cylindrical electrode and the inner cylindrical electrode. The excimer laser device according to claim 1, wherein the excimer laser device is configured so as to meet the above requirements.