JPH04288887A - Excimer laser device - Google Patents

Abstract

PURPOSE:To enable a gas life of an excimer laser device to be extended and a high-quality beam to be attained by eliminating a fine particle which induces deterioration of discharge or deterioration of gas efficiently and without disturbing as flow. CONSTITUTION:In an excimer laser device, an electrode 2 which is sputtered by discharge is constituted by Ni, etc., which are rich in halogen resistance property, an electromagnet 9 or a permanent magnet 9 is used as a filter for eliminating fine particles paying attention to the fact that the electrode material and a halide are magnetic bodies and at the same time a filter device 4 is placed on a side of a gas flow path without screening the gas circulation flow path directly.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an excimer laser device, and more particularly to an excimer laser device for extending the life of the laser gas and improving the quality of the laser beam.

0002

2. Description of the Related Art FIG. 3 is a block diagram showing a conventional excimer laser device of this type. In the figure, 1 is a laser chamber that houses a pair of electrodes 2 inside, 3 is an optical component such as a mirror provided at both ends of the laser chamber 1,
4 is a filter device having a mechanical filter 5 attached therein, and 6 is a gas purification device. The laser chamber 1, the filter device 4, and the gas purification device 6 are connected in series through an external pipe 7, and the whole constitutes a sealed container in which a laser gas 8 such as KrF is sealed. Further, this laser gas 8 is circulated in the direction shown by the arrow in the figure by a circulation device (not shown).

In the excimer laser device, the electrodes 2 themselves are sputtered by the discharge between the electrodes 2 in the laser chamber 1, and become fine particles that float in the gas space. If such fine particles exist in the discharge space, the desired uniform discharge is disturbed, causing problems such as the intensity distribution of the laser beam becoming non-uniform and the output becoming unstable. In addition, excimer laser devices use halogen gases such as F and Cl as medium gases, but since these halogen gases are enclosed in only trace amounts compared to rare gas buffers such as Ne and He, small amounts of impurities may be present. The effect of laser output reduction due to particles and particles is noticeable. Therefore, by driving a circulation device such as a pump, the laser gas 8 in the laser chamber 1 is sent to the filter device 4 via the external piping 7, and the particulates in the gas are removed by passing through the mechanical filter 5 inside the filter device 4. Furthermore, impurities are removed by circulating the gas purifier 6. In this way, we aim to improve the quality of the laser beam and extend the life of the laser gas.

0004

SUMMARY OF THE INVENTION As described above, in the conventional excimer laser device, the mechanical filter 5 removes fine particles generated by discharge. By the way, this mechanical filter 5 is formed of, for example, a fine lattice-like filter, but in its application, it is necessary to have a structure that allows the circulating gas flow to pass through this filter. Therefore, if the mesh of the filter is made finer in an attempt to remove finer particulates, the gas flow will be obstructed, and conversely, if the mesh is made coarser so as not to impede the gas flow, finer particulates will not be removed. Furthermore, if a fine-mesh filter captures particulates, it obstructs the flow of gas and reduces the subsequent capture ability, resulting in problems such as the need for frequent and complicated filter replacement. The present invention was made to solve the above-mentioned problems, and an object of the present invention is to obtain an excimer laser device that can remove fine particles without interfering with the flow of laser gas.

[0005]

[Means for Solving the Problems] An excimer laser device according to the present invention is one in which a magnet is provided in a container that accommodates a pair of electrodes and seals in laser gas.

[0006]

[Operation] Fine particles generated by the discharge between the electrodes move within the container together with the laser gas, and when they reach the vicinity of the magnet, they are captured by the magnet due to magnetic attraction.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram showing an excimer laser apparatus according to an embodiment of the present invention. In the figure, since the filter device 4 is different from the conventional one, this point will be mainly explained below. That is, in the filter device 4 of this embodiment, the magnet 9 is provided at the bottom of the space where the cross section of the flow path is enlarged to reduce the gas flow velocity. This magnet 9 may be a permanent magnet or an electromagnet. Then, the fine particles are captured by the magnetic attraction force of the magnet 9.

That is, in an excimer laser device using KrF gas as the laser gas 8, Ni, which is a material with relatively high fluorine resistance, is used for the electrode 2, and its fine particles react with fluorine. NiF and the like are generated, but since these are all magnetic substances, they can be almost captured by the magnet 9. Therefore, in the laser chamber 1, fine particles and their fluorides generated by sputtering etc. of the discharging electrode 2 are sent together with the laser gas 8 by the circulation device via the external piping 7 to the filter device 4, where they are captured by the magnet 9. removed from the gas. Furthermore, impurities are removed from the gas discharged from the filter device 4 by a gas purification device 6, and the gas returns to the laser chamber 1 free of fine particles and impurities. As a result, the discharge within the laser chamber 1 and therefore the laser output are stabilized, and the life of the gas is also increased. In this case, the magnetic attraction force of the magnet 9 attracts, captures and removes fine particles, so the magnet 9 only needs to be placed beside the gas flow path, and the gas flow as in the case of the conventional mechanical filter 5 is used. Since there is no need for a configuration that blocks gas, there is no risk that gas circulation will be hindered. In addition, the ability to capture particulates hardly decreases, so there is no need to replace the filter as often as in the past. However, since it is necessary to check whether there are any abnormalities in the amount of fine particles generated, or to discharge a large amount of fine particles that have accumulated, for example, the filter device 4
It is better to have a structure in which the lower part of the magnet 9 can be opened so that the magnet 9 can be taken out and replaced.

FIG. 2 shows another embodiment of the invention, and each reference numeral corresponds to the same reference numeral in the embodiment of FIG. Here, a filter device 4 is set in one corner of the laser chamber 1, and a magnet 9 is attached inside the filter device 4. 10 is a fan that circulates the laser gas 8 within the laser chamber 1. Fine particles generated by the discharge between the electrodes 2 are circulated within the laser chamber 1 by a fan 10, captured by a magnet 9, and removed from the gas.

0010

[Effects of the Invention] As described above, in this invention, a magnet is provided inside the container, and the fine particles generated by the discharge between the electrodes are captured by the magnet, so that almost no complicated maintenance work is required. This results in higher quality laser beams and longer life of the laser gas.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing an excimer laser device according to an embodiment of the present invention.

FIG. 2 is a configuration diagram showing an excimer laser device according to another embodiment of the present invention.

FIG. 3 is a configuration diagram showing a conventional excimer laser device.

[Explanation of symbols]

1 Laser chamber 2 Electrode 4 Filter device 8 Laser gas 9 Magnet

Claims (1)

[Claims] Claim 1: An excimer laser device that houses a pair of electrodes in a container and encloses a laser gas, and generates laser light by excitation of a discharge between the two electrodes, wherein a magnet is provided in the container, and the laser gas is generated by the discharge. 1. An excimer laser device characterized in that said magnet captures fine particles by its magnetic attraction force.