JPH0341790A - Gas laser - Google Patents

Abstract

PURPOSE:To obtain a gas laser provided with a fine particle removing mechanism having little pressure loss of a gas flow and having the high capture efficiency of fine particles by a method wherein a fine particle capturing/removing means is provided on the wall surface of the interior of the bend part of a gas flow path in the circulating path of laser gas. CONSTITUTION:A fine particle removing mechanism is formed into a constitution, in which a circulating path constituted in a laser chamber 2 is provided between discharge electrodes 4 and gas coolers 5 and a gas circulating fan 3 circulates forcedly laser gas. Thereby, a bent gas flow F is formed in the bend part of the circulating path. A fine particle adsorbing material 1 is provided on the inner wall of the bend part, which comes into contact to this gas flow F, of the circulating path. As the flow F changes abruptly its direction at the bend part, which is provided with the material 1, of the circulating path, a centrifugal force to head for the outside works on fine particles in the flow F. Owing to this, the fine particles are driven out from the flow F to the outside and collide with the material 1. An enormous number of holes of a diameter of 10mum to several mm exist in the surface of the material 1 consisting of a porous thin film material and the fine particles are captured in these holes and are removed from the interior of the laser gas.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a gas laser device equipped with a particulate removal mechanism, which is applied to, for example, an excimer laser device.

[Prior Art] Gas laser devices that have been developed for various uses and are used in many fields, especially gas laser devices that generate relatively high output by discharge excitation of forcedly circulated laser gas, have a tendency to gaseous or particulate impurities are generated and accumulated within the laser chamber. These impurities are generated when electrode materials, etc. evaporate and re-solidify, organic substances remaining in the laser chamber are decomposed, or new substances are synthesized from laser gas and impurities, and they increase over time. and contaminate the laser gas. These impurities absorb laser light related to optical resonance and reduce laser output. It also disturbs the electric field distribution in the discharge region and impedes the movement of gas molecules, making the discharge unstable. Therefore, as the amount of fine particles in the laser gas increases, the performance of the gas laser device is significantly reduced. In particular, discharge-type excimer laser equipment uses chemically active halogen gas, which generates a large amount of fine particles.As the laser gas circulates at high speed, these fine particles invade the discharge area and interfere with the normal operation of the equipment. lost in a relatively short period of time.

Therefore, a typical discharge type excimer laser device is provided with an impurity removal mechanism to suppress the amount of impurities in the laser gas below a certain level.

Among impurities, low-temperature removal devices that utilize adsorption and coagulation at low temperatures have been put into practical use for gaseous or liquid particulates. However, since the low temperature cannot be expected to cause adsorption or coagulation of the solid particles that fly up and circulate within the chamber due to the forced circulation of the laser gas, attempts have been made to insert a filter into the laser gas flow path to capture and remove them.

FIG. 5 shows the configuration of a first conventional excimer laser device equipped with a particulate removal mechanism. The first conventional example has a configuration in which laser gas in a laser chamber 2 is circulated as a gas flow F between a discharge electrode 4 and a gas cooler 5 by a gas circulation fan 3. Here, a filter 7 formed of a fine mesh of stainless steel is installed on the gas circulation path,
Captures fine particles. In the first conventional example, as described later,
Although pressure loss in the laser gas circulation path in the filter 7 poses a problem, particulates circulating together with the laser gas always pass through the filter 7.

FIG. 6 shows the configuration of a second conventional excimer laser device that solves the pressure loss in the laser gas circulation path. 1st
The same reference numerals are given to members having the same configuration and functions as in the conventional example.

The second conventional example includes a duct 10, a filter 8, and a circulation pump 9.
It has a subcirculation path consisting of a subcirculation path, and is configured to take out a part of the laser gas in the chamber 2, remove particulates with a filter 8, and then forcibly return it into the chamber 2.

[Problems to be Solved by the Invention] In the excimer laser device of the first conventional example, the filter 7 is
Since the entire gas flow path in the gas circulation path is blocked, increasing the mesh density to increase the capture efficiency increases the pressure loss of the laser gas flow. However, if the mesh density is lowered, the pressure drop will be lowered, but the efficiency of capturing fine particles will also be lowered. In addition, the filter 7 becomes clogged with particulates as the device operates, increasing pressure loss and obstructing the gas flow F.

In the second conventional excimer laser device, the pressure loss in the laser gas circulation path in the chamber 2 is unrelated to the filter 8, but particles circulating in the laser gas circulation path in the chamber 2 that do not pass through the filter 8 are not captured. , the effect of the filter 8 is limited. Further, if the capacity of the pump 9 is improved, the effectiveness of the filter 8 will be increased, but increasing the capacity of the pump 9 is inconvenient from the viewpoint of manufacturing and maintenance of the device.

SUMMARY OF THE INVENTION An object of the present invention is to provide a gas laser device equipped with a particulate removal mechanism that has a small gas flow pressure loss and high particulate capture efficiency.

[Means for Solving the Problems] A gas laser device according to the present invention includes gas circulation means for circulating laser gas within a laser chamber. Further, a removing means for capturing particulates is provided on the inner wall surface of the curved portion of the gas flow path in the laser gas circulation path.

[Function] The gas circulation means of the gas laser device according to the present invention forcibly circulates the laser gas in the laser chamber to efficiently cool the laser gas, prevent rapid deterioration of the laser gas, and stabilize the discharge state. maintain. However, as the gas laser device is operated, unnecessary particles gradually increase in the laser chamber and contaminate the laser gas. The gas circulation means mixes and stirs the particles in the laser gas.

Furthermore, since the removing means is provided in parallel with the flow of the laser gas, it does not directly impede the flow of the laser gas.However, the removing means is provided on the inner wall of the bend in the gas flow path, especially on the inner wall outside the bend. , fine particles can be efficiently separated and captured from laser gas. That is, the bending of the laser gas flow causes a centrifugal force to act on the particles, causing them to concentrate outward and collide with the removal means.

[Example] FIG. 1 shows a schematic configuration of a gas laser device according to a first example of the present invention. A circulation path including a laser chamber 2 is provided between the discharge electrode 4 and the gas cooler 5, and a gas circulation fan 3 is configured to forcefully circulate the laser gas. As a result, a bent gas flow F is formed at the bend in the circulation path.

A particulate adsorbent 1 is provided on the inner wall of the curved portion of the circulation path that is in contact with this gas flow F.

Since the particulate adsorbent 1 comes into direct contact with the chemically active laser gas, various materials with high corrosion resistance are used. That is, a corrosion-resistant metal (SUS316L, Ni, etc.), a corrosion-resistant organic material (fluororesin, etc.), or a corrosion-resistant ceramic is used. In addition, the processed shape can be a mesh, a porous thin film material, or a wool-like 1IiI that is bundled and fixed with a mesh to prevent it from falling apart! Each shape of the fiber is selected.

Here, a porous thin film material made of fluororesin was used.

Since the gas flow F suddenly changes direction at a bend in the circulation path where the particulate adsorbent 1 is provided, centrifugal force acts on the particulates in the gas flow F toward the outside. Therefore, the particulates are driven outward from the gas flow F and collide with the particulate adsorbent 1. On the surface of the fine particle adsorbent 1, which is a porous thin film material,
There are a huge number of holes with diameters ranging from 10 μm to several mm, and fine particles are trapped in these holes and removed from the laser gas.

FIG. 2 shows a schematic configuration of a gas laser device according to a second embodiment of the present invention, and members having the same configuration and functions as those in the first embodiment are given the same reference numerals. Here, the curved portion of the circulation path is divided into a plurality of parallel gas flow paths to form respective gas flows F. A particulate adsorbent 1 is provided for each gas flow path, and particulates are removed from each gas flow F. In the second embodiment, since the contact surface area between the particulate adsorbent 1 and the gas flow F can be increased compared to the S1 embodiment, particulates can be captured more efficiently.

The particulate adsorbent 1 may be composed of only particulate adsorbent, but may be provided with a reinforcing structure so as to have strength as a partition wall for each gas flow F. This reinforcing structure may be either a breathable or non-breathable structure.

FIG. 3 shows a schematic configuration of a gas laser device according to a third embodiment of the present invention, and members having the same configuration and functions as those in the first embodiment are given the same reference numerals. Here, the curved portion of the circulation path is formed by the opposing particulate adsorbents 1, and a gas flow F is generated in which the bends of the particulate adsorbents 1 follow a V-shape. Also at this curved portion, separation and fixation of particles from the laser gas is performed in the same manner as in the first embodiment.

FIG. 4 shows a schematic configuration of a gas laser device according to a fourth embodiment of the present invention, and members having the same configuration and functions as those in the first embodiment are given the same reference numerals. Here, the particulate adsorbents 1 have a vertical shape, and the curved portions of the circulation path are formed by the vertical particulate adsorbents 1 placed alternately in the laser gas circulation path. The gas flow path between the opposing particulate adsorbents 1 forms a gas flow F that is sharply bent. Even at this bent portion, separation and fixation of particles from the laser gas is performed in the same manner as in the first embodiment.

In each of the above embodiments, the particulate adsorbent 1 may have a structure in which part of the laser gas passes through while removing particulates, or may have a structure in which the particulates that collide with the surface are captured without the laser gas passing through. It is also possible to form a bent part of the circulation path into an integral unit containing the particulate adsorbent 1, and to have a structure that can be freely inserted into and removed from the circulation path. At this time, the structure of the bend in the circulation path is
More free selection is possible, and for example, it is possible to create a three-dimensional structure that separates fine particles by forming a spiral flow that scans the inner surface of the cylinder in a coil shape.

In the gas laser device of each example, the particulate adsorbent 1
Since the pressure loss of the gas flow F is smaller than that in the conventional example, the burden on the gas circulation fan 3 is reduced. Further, even in the case of a relatively small capacity gas circulation fan, high-speed gas circulation and efficient removal of particulates in the laser gas are both compatible.

Further, when the particulate adsorbent 1 becomes clogged with particulates due to the operation of the apparatus, although the particulate trapping efficiency decreases, the pressure loss does not increase as in the conventional example.

[Effects of the Invention] Since the gas laser device according to the present invention maintains the cleanliness of the laser gas by removing fine particles in the laser gas using the removing means, absorption and scattering of laser light by the fine particles is suppressed, and abnormal discharge in the laser gas is suppressed. This makes it possible to take out the laser output stably for a long period of time, and the life of the laser gas is also extended.

In addition, the removal means has a structure that does not directly impede the flow of the laser gas and can reduce pressure loss, making it possible to reduce the capacity of the gas circulation means. Furthermore, the bends in the circulation path make separation of particles from the laser gas efficient.
By combining it with a removal means, it becomes possible to remove particles more efficiently and with higher performance.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing the general configuration of a gas laser device according to a first embodiment of the present invention. FIG. 2 is a schematic diagram showing the general configuration of a gas laser device according to a second embodiment of the present invention. FIG. 3 is a schematic diagram showing the general configuration of a gas laser device according to a third embodiment of the present invention. FIG. 4 is a schematic diagram showing the general configuration of a gas laser device according to a fourth embodiment of the present invention. FIG. 5 is a schematic diagram showing the general configuration of a conventional gas laser device. FIG. 6 is a schematic diagram showing the general configuration of another conventional gas laser device. [Explanation of symbols of main parts]

Claims (1)

[Scope of Claims] The present invention is characterized by comprising a gas circulation means for circulating laser gas in a laser chamber, and a removal means for capturing particulates on an inner wall surface of a curved part of a gas flow path in the laser gas circulation path. gas laser equipment.