JPH01140689A - Gas laser apparatus - Google Patents

Abstract

PURPOSE:To obtain high flow rate of laser medium gas, by providing a blower on each of the upstream and downstreatm sides of a position in a passage where loss of pressure is maximum. CONSTITUTION:A pair of cross flow fans 108a, 108b are arranged at the positions in a laser medium gas circulating passage where loss of pressure is maximum, namely they are arranged one by one on the opposite sides of a heat exchanger 109. Thus, laser medium gas fed into the heat exchanger 109 by the cross flow fan 108b is again accelerated by the other cross flow fan 108a and fed into a space between principal discharge electrodes 105a and 105b. In this manner, flow rate of the laser medium gas can be increased and high output can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a lateral discharge-excited gas laser device such as an excimer laser.

(Prior Art) In recent years, laser processing machines that use laser light as an energy source have been put into practical use, but their processing performance largely depends on the laser output. In particular, gas laser devices such as excimer lasers have a wide range of applications, and are particularly required to have high output.

The structure of a conventional lateral discharge-excited gas laser device and problems associated with increasing its output will be explained using an excimer laser as an example.

FIG. 3 shows a conventional excimer laser device.

In FIG. 3, preliminary ionization electrodes 304a and 304b are provided in the laser chamber 301, and a main discharge electrode 3 is provided in the vicinity thereof.
05a, 305b are provided, main discharge electrodes 305a, 3
05b serves as a flow path through which the laser medium gas flows. 309 is a heat exchanger for cooling the laser medium gas, and 308 is a cross-flow fan for circulating the laser medium gas in the direction of arrow A.

In such a configuration, the prediction is 0! Ionization electrodes 304a, 30
4b to generate arc discharge and perform ultraviolet preliminary ionization.

When the voltage between the terminals of a discharge capacitor (not shown) reaches a certain threshold, a main discharge occurs between the main discharge poles 305a and 305b, and the laser medium gas between the main discharge poles 305a and 305b is excited. Laser oscillation is amplified between laser resonators (not shown) installed at both ends of the laser chamber 301.

Since the laser medium gas is degraded by the pre-ionization electrodes 304a, 304b and the main discharge electrodes 305a, 305b, it is circulated in the direction of arrow A by a cross-flow fan 308 and cooled by a heat exchanger 309.

The cooled and regenerated laser medium gas is transferred to the discharge region, that is, the pre-(1wt separation electrode 304
a, 304b is sent between the main discharge electrodes 305a05b.

In the case of an excimer laser, the laser medium gas is generally strongly excited in a short period of several + n5 ec to cause pulse oscillation, so the laser medium gas deteriorates significantly with each pulse oscillation, and regeneration requires a certain amount of time.

Therefore, if the next main discharge is performed before the laser medium gas deteriorated by the main discharge is completely removed from the main discharge region, the main discharge becomes unstable and the pulsed laser output decreases.

Therefore, it becomes necessary to circulate the laser medium gas at high speed.

That is, in order to increase the flow velocity of the laser medium gas near the main discharge poles, (1) the once-through fan is rotated at high speed;

(2) Increase the size of the once-through fan.

(3) Optimize the position of the once-through fan and the gas flow path.

Measures such as these are being taken.

FIG. 4 shows a conventional example in which the measure (3) above is taken. Fourth
In the figure, an outer guide 40 is placed inside a laser chamber 401.
2a, 402b are provided, and outer guides 402a, 402b are provided.
and the main discharge pole 4.degree. 5a form the outer wall of the laser medium gas flow path.

Moreover, the main discharge Bi 405b and the inner guide 407 form the inner wall of the laser medium gas flow path.

With this configuration, the once-through fan 408 is rotated to circulate the laser medium gas in the direction of arrow A, and the heat exchanger 409 cools it.

(Problems to be Solved by the Invention) However, various countermeasures have been taken in such conventional gas laser devices, but (a) a heat exchanger is inserted in the gas flow path, which obstructs the flow of the laser medium gas; do.

(b) Compared to the gas flow path, the distance between the main discharge electrodes is extremely narrow and the pressure loss in the flow path becomes large.

(C) Due to the structure of the excimer laser, there are protrusions such as pre-ionization electrodes near the main discharge poles, which causes problems such as turbulence and increased pressure loss in the flow path.

Moreover, in the case of (a) above, it is impossible to remove the heat exchanger or remove it from the laser medium gas flow path because it is necessary to cool and regenerate the laser medium gas, and in cases of (b) and (C), it is impossible to remove the heat exchanger from the laser medium gas flow path. There has been a limit to the improvement of pressure loss in the flow path due to problems such as the size and shape of the discharge circuit, etc.

In particular, once-through fans have a small head compared to other blowers, and even a small pressure loss in the flow path can cause a significant drop in performance, so improving pressure loss has been a big problem.

(Means for Solving the Problems) The present invention solves the problem by eliminating obstacles, protrusions, etc. in the laser medium gas flow path.
The idea is to compensate for the pressure loss in the flow path caused by flow path resistance, etc. by adding a cross-flow fan, and to obtain a high flow rate of the laser medium gas.

That is, the above-mentioned problem is solved by adding more cross-flow fans than the conventional one and installing them across the point where the pressure loss is greatest.

(Function) The once-through fan located upstream of the point with the largest pressure loss acts to send the laser medium gas, and the once-through fan installed downstream reduces the pressure as it passes through the point with the largest pressure loss. It acts to increase the flow rate of the laser medium gas.

(Example) A first embodiment of the second invention will be described based on FIG.

In FIG. 1, an outer guide 10 is placed inside a laser chamber 101.
2a, 103a, 102b, 1.03b, preliminary ionization electrodes 104a, 104b, main discharge electrodes 105a, 105b, and outer guides 102a, 103a.
, 102b, 103b and the main discharge electrode 105a form the outer wall of the laser medium gas flow path.

Further, the main discharge electrode 105b and the inner guide 107 provided below it form the inner wall of the laser medium gas flow path.

Reference numerals 108a and 108b indicate once-through fans, which are installed on both sides of the heat exchanger 109, and direct the laser medium gas in the directions indicated by arrows A and B.
Circulate in the direction of.

In the above configuration, if the excitation intensity of the laser medium gas is increased in order to increase the energy per pulse of the laser, the deterioration of the laser medium gas will be significant, and the heat exchanger 109 for regeneration will become large-scale. .

Therefore, the pressure loss of the laser medium gas circulating through the heat exchanger 109 increases, the flow rate of the laser medium gas decreases, and high repetition oscillation becomes difficult.

Therefore, a total of two cross-flow fans 108a and 108b are installed, one on each side of the heat exchanger 109, at the point where the pressure loss is greatest in the flow path where the laser medium gas circulates. The fed laser medium gas is accelerated again by the cross-flow fan 108a and sent between the main discharge electrodes 105a and 105b.

In this embodiment, the diameters and rotation speeds of the cross-flow fans 108a and 108b may be different from each other.

A second embodiment of the invention will be described based on FIG. 2.

In FIG. 2, an outer guide 20 is placed inside the laser chamber 201.
2a, 203a, 202b, 203b and pre-ionization electrodes 204a, 204b main discharge electrodes 205a, 205b are provided, and outer guides 202a, 203a, 202b,
203b and the main discharge electrode 205a form the outer wall of the laser medium gas flow path.

Further, the main discharge electrode 205b and the inner guides 207a, 207b, and 207C provided around it form the inner wall of the laser medium gas flow path.

208a, 208b, and 208C are cross-flow fans, and one cross-flow fan 208a, 208b is installed on each side of the gap created by the main discharge electrodes 205a and 205b, and one cross-flow fan is installed near the heat exchanger 209. 208C
is installed to circulate the laser medium gas in the directions of arrows A, B, and C.

The laser chamber 201 of this embodiment has a size that is not strictly limited and has a width W that is larger than that of the first embodiment.

In addition, since the energy per pulse is small, there is no need to make the heat exchanger 2o9' large and the pressure loss is small. Rather, the main discharge electrodes 205a and 205b act as a throttle in the laser medium gas flow path. Therefore, pressure loss is maximum at this point.

Therefore, cross-flow fans 208a on both sides of this point.

208b is installed to allow pressure loss to flow through and be recovered by the fan 208b.

In addition, in this embodiment, rll W of the laser chamber 201
Since the laser medium gas flow path becomes longer and the flow path resistance increases, the flow fan 208
c is installed.

Also in this embodiment, each cross-flow fan 208a, 208b,
208C may have different diameters and rotational speeds.

(Effects of the Invention) According to the present invention, the flow velocity of the laser medium gas is increased and it becomes possible to make the laser output high.

In particular, pulsed gas lasers such as excimer lasers have become capable of high repetition oscillation while maintaining high energy per pulse, making them applicable to semiconductor manufacturing equipment and the like.

[Brief explanation of the drawing]

FIG. 1 shows a first embodiment of the invention, FIG. 2 shows a second embodiment of the invention, and FIGS. 3 and 4 show a prior art. In the figure, 101.201.301.401 are laser chambers, 102a, 102b, and 202a. 203a, 202b, 203b, 402a, 402b are outer guides, 105a, 105b, 205a, 205b
are the main discharge electrodes, 107.207a, 207b, 407 are the inner guides 1, 108a, 108b, 208a, 208
b, 208 c. 308.408 is a cross-flow fan, 109.209.309
．． 409 is a heat exchanger. Applicant: Komatsu Ltd. Agent (Patent Attorney) Oka 1) Kazuyuki Figure 1 Figure 2

Claims (1)

[Claims] In a gas laser device in which a flow path for circulating laser medium gas between the main discharge electrodes is formed by an outer guide and an inner guide provided in the laser chamber, and a heat exchanger and a blower are provided in the flow path, the flow is A gas laser device characterized in that a blower is provided upstream and downstream of the position of maximum pressure loss in the path.