JPH06125123A - Laser case body of gas laser system and gas exhausting method from laser case body - Google Patents

Abstract

PURPOSE:To provide a gas laser system and gas exhausting method from laser case body capable of efficiently removing any moisture content, impurity gas, etc., in the laser case body within a short time as well as decreasing the frequency of passivation processing times. CONSTITUTION:During the gas exhausting step of passivation process repeating the filling step of laser medium gas, the laser oscillating step and the polluted gas exhausting step, the polluted gas is exhausted while heating a case body 6 after filling a heater jacket 7 provided in the case body 6 with a heating medium.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas laser housing and a method for exhausting an impurity gas such as water adhered to the inner wall of the gas laser housing and the components inside the housing.

[0002]

2. Description of the Related Art When exchanging a laser medium gas of a laser casing constituting a gas laser oscillating section, it is first necessary to exhaust an impurity gas such as moisture adhering to an inner wall of the casing and constituent members in the casing. As this exhaust method, there is a passivation process (passivation process) in which the filling of the laser medium gas, the laser oscillation, and the discharge of the dirty gas are repeated, and a technique of this kind is disclosed in, for example, Japanese Utility Model Publication No. 1-146567. There is something. That is, FIG. 9 is a schematic view of a gas exhaust device in the laser housing of the conventional gas laser apparatus shown in the above publication, and FIG. 10 is a process diagram from assembly of the conventional gas laser housing to shifting to steady operation. In the figure, 1 is a housing constituting a gas laser oscillator, 2 is an exhaust pipe connected to the exhaust opening 1a of the housing 1, 3 is an exhaust valve, 4 is a halogen gas treatment device, and 5 is an exhaust pump. When exchanging the gas in the housing 1, the exhaust valve 5 is driven and then the exhaust valve 3 is opened to exhaust the gas remaining in the housing 1 through the exhaust pipe 2.

In the conventional gas laser device, the life of the gas in the housing 1 has not been so much a problem, and the main purpose of exhausting the residual gas in the housing 1 is to replace the laser medium gas. It was Particularly, in the excimer laser, a predetermined laser output and laser characteristics cannot be obtained for a while after the laser device is assembled. This is due to the high reactivity of the halogen gas. That is, after the housing of the laser device is assembled, the inner wall of the housing and the internal components are in a state of not reacting with the halogen gas at all, and such a housing is filled with the laser medium gas containing the halogen gas to cause the laser oscillation. This is because the water or dirt components adhering to the inner wall of the housing and the internal components react violently with the halogen gas, and the laser gas becomes dirty and deteriorates in an extremely short time. However, by performing the so-called passivation treatment in which laser oscillation and gas exchange are repeated as described above, a reaction product of the member and the halogen gas is formed on the inner wall of the housing and the surfaces of the internal constituent members. Due to the protective effect of, the reaction becomes difficult to proceed. In addition, the dirt component is discharged outside the housing during gas exchange, so it gradually decreases, and as a result, the laser output,
Laser characteristics will improve.

[0004]

As the excimer laser has been put to practical use as a light source for a semiconductor exposure apparatus, the life of the laser medium gas has become a problem. In particular, when impurity gas such as moisture is adsorbed on the inner wall of the housing, when the housing is filled with a medium gas containing a halogen gas to cause laser oscillation,
A reaction of H ₂ O + F ₂ → 2HF + 1/20 ₂ occurs inside the housing, the concentration of F ₂ is reduced, and the generated hydrogen fluoride gas and oxygen gas cause a remarkable reduction in laser oscillation efficiency.
Therefore, in order to remove the impurity gas such as water adhered to the inner wall of the housing and to adapt the portion of the housing that comes into contact with the laser medium gas with the above gas, a fresh gas as the laser medium gas is filled 10 ⁴ to 10 10. ^The passivation process is performed by repeating the discharge (laser oscillation) of about ⁵ sailboats and exhausting dirty gas until the reduction rate of the laser output falls below a predetermined value. There is a problem that it is extremely inefficient and uneconomical because it requires a large number of repetitions over a long period of time.

The present invention has been made in order to solve the above problems, and it is possible to efficiently remove water and the like in the housing in a short time and reduce the number of passivation processes. It is also an object of the present invention to obtain a method for exhausting gas inside the laser housing.

[0006]

[Means for Solving the Problems] Claim 1 according to the present invention
The method for exhausting gas from the laser housing of the gas laser device is such that the housing is heated and exhausted in the gas discharge step in the passivation process in which filling of the laser medium gas, laser oscillation, and exhaust of dirty gas are repeated. is there.

Further, in the laser casing of the gas laser device according to the second aspect, a passage is provided on the outer peripheral surface of the laser casing so as to surround the passage, and a heating medium is circulated in the passage to heat the inside of the casing. The laser housing of the gas laser device according to claim 3 is configured such that a heater is provided in the laser housing and the inside of the housing is heated by the heater.

[0008]

According to the method of exhausting gas in the laser housing of the gas laser device of the present invention, the number of times of passivation processing is reduced because high vacuum exhaust is performed while heating the inside of the laser housing.

[0009]

【Example】

Example 1. Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram of a heating jacket provided on a laser housing of a gas laser device according to a first embodiment of the present invention.
In FIG. 1, reference numeral 6 denotes a housing for forming a gas laser oscillation part, which is manufactured using 18Cr8Ni-based austenitic stainless steel that emits a small amount of emitted gas, and the surface in contact with the laser medium gas is mirror-finished to reduce the area. There is. Reference numeral 7 is a jacket for heating the housing 6, and a passage (not shown) for circulating a heating medium therein.
Are formed. Reference numeral 8 is an inlet for introducing the heating medium into the jacket 7, and 9 is an outlet. Reference numeral 10 is a main exhaust pipe for the laser medium gas, and an exhaust valve 11 and a high vacuum exhaust pump 1 for exhausting gas in the housing are provided in the middle thereof.
Two are provided. Reference numeral 13 denotes an auxiliary exhaust pipe branched from the main exhaust pipe 10, and an exhaust valve 14 and an exhaust pump 15 are provided in the middle thereof.

In the gas exhaust method using the laser casing constructed as described above, after assembling the casing 6, hot oil of 150 ° C. is injected from the inlet of the jacket 7 to form the casing 6.
The inside of the housing 6 is baked by driving the high vacuum exhaust pump 12 while heating the inside, and the housing 6 is also exhausted while heating in the gas discharging step in the passivation process of the next step. Then, the process is shown in FIG.
Is shown in. FIG. 6 shows the steps from the assembly of the housing 6 to the start of steady operation in the first embodiment. The step of heating and baking the inside of the housing 6 between the assembly of the housing 6 and the passivation process. However, in the passivation process, a step of exhausting the inside of the housing 6 while heating is inserted. Therefore, as compared with the conventional case where the inside of the housing is not heated, the removal of the impurity gas such as moisture in the housing is efficiently achieved in a short time, and the number of passivation treatments can be significantly reduced.

The high vacuum pump 12 shown in the figure may be removed after the baking is completed and replaced with a normal exhaust pump. That is, the gas exchange does not necessarily require the high vacuum pump 12, and may use a small exhaust valve 14 and an auxiliary exhaust pipe 13 provided with an exhaust pump 15 that are easy to handle. Further, during laser oscillation, instead of hot oil, cold water of 20 ° C. or less may be caused to flow through the jacket 7 to suppress an internal temperature rise, which may be useful for improving laser oscillation efficiency.

FIG. 8 is a diagram showing the relationship between the number of passivation treatments after baking and the number of gas laser output halves, and also shows a conventional example in which baking is not performed for comparison. As can be seen from FIG. 8, in the case of baking (heating at 150 ° C., high vacuum evacuation), it is possible to oscillate 10 ⁷ or more yachts before the laser output is halved in the second passivation treatment, whereas conventional baking is not performed. In the case of, even if 10 times passivation processing is performed, 10 ⁶ sailboats cannot oscillate. Further, the baking temperature as high as 150 ° C. rather than 50 ° C. is more effective in reducing the number of passivation treatments. That is, if the baking temperature is increased as much as the heat resistance of the constituent members in the housing allows, the effect of removing the impurity gas such as moisture in the housing is greater. From the above results, baking is effective in removing the impurity gas such as water in the housing, enables the number of passivation treatments to be reduced, and further, the laser medium gas is charged once when the laser oscillation enters the steady operation. It can be seen that there is an effect of lengthening the oscillation time in.

Example 2. FIG. 2 is a schematic diagram showing the configuration of the laser housing of the gas laser device according to the second embodiment of the present invention. In the first embodiment described above, the heating jacket 7 for circulating the hot oil as the heating medium is provided on the outer surface of the housing 6, but in the second embodiment, the heating jacket 7 is heated around the housing 6. The pipe 16 is wound, and hot oil of 150 ° C. is injected from the inlet 8 when baking the casing 6, and the high vacuum exhaust pump 12 is driven while heating the inside of the casing 6 to perform high vacuum exhaust. Degassing is performed, and in the gas discharging step in the passivation process, the inside of the housing 6 is exhausted while being heated, and the same effect as that of the first embodiment is achieved. Further, at the time of laser oscillation, it is possible to suppress an increase in the internal temperature of the housing 6 by injecting cold water of 20 ° C. or lower from the injection port 8.

Example 3. FIG. 3 is a schematic diagram showing the configuration of the laser housing of the gas laser device according to the third embodiment of the present invention. In FIG. 3, reference numerals 17 and 18 denote heating heaters disposed inside the housing 6. The heating heater 17 is a microsheath heater, and the heating heater 18 is a halogen lamp heater. In both cases, the temperature can be controlled by the amount of electric current to be applied.
The same effect as 2 is achieved. Further, the halogen lamp heater 18 is fixed to the housing 6 via the sealing material 19 and has a detachable structure. After the baking is completed, the halogen lamp heater 18 is removed from the housing 6 and is closed with a blind plug.

Example 4. Fourth Embodiment FIG. 4 is a schematic diagram showing the configuration of a laser housing of a gas laser device according to a fourth embodiment of the present invention. In FIG. 4, reference numeral 20 is a tape heater attached to the outer surface of the housing 6 and has the same effect as that of the first to third embodiments. The tape heater 20 is detachable, and is removed after the baking is completed.

Example 5. FIG. 5 is a schematic diagram showing a heating configuration of a laser housing of a gas laser device according to a fifth embodiment of the present invention. In FIG. 5, reference numeral 21 is an oven having a size capable of accommodating the entire housing 6, and the housing 6 is housed in the oven 21, the housing 6 is housed in the oven 21, and baking and passivation are performed while heating the housing 6. Processing is performed, and the same effect as that of the above-described first to fourth embodiments is obtained. According to the housing heating configuration using the oven 21 of the fifth embodiment, it is only necessary to take out the housing 6 from the oven 21, and it is not necessary to attach or detach the heater unlike the third and fourth embodiments. There is.

Embodiment 6. FIG. 7 is a process diagram from assembly of a housing to shifting to steady operation in Embodiment 6 of the present invention.
As shown in FIG. 7, before assembling the internal components including the housing, after thoroughly degreasing and cleaning, these are housed in an oven and heated to 150 ° C. or higher, baking is performed, and then the housing is Assemble the body. By doing this,
Impurity gas such as moisture in the housing and internal components can be removed to a more complete state, which has a favorable effect on the passivation process in the subsequent process.

[0018]

As described above, according to the present invention, in the gas discharging step in the passivation process in which the filling of the laser medium gas, the laser oscillation, and the exhaust of the dirty gas are repeated, the inside of the housing is exhausted while heating. , The number of passivation processes can be significantly reduced.

[Brief description of drawings]

FIG. 1 is a schematic diagram in which a heating jacket is provided on a laser housing of a gas laser device according to a first embodiment of the present invention.

FIG. 2 is a schematic diagram in which a heating pipe is provided in a laser housing of a gas laser device according to a second embodiment of the present invention.

FIG. 3 is a schematic view of a heater provided in a laser housing of a gas laser device according to a third embodiment of the present invention.

FIG. 4 is a schematic diagram in which a tape heater is provided on an outer surface of a laser housing of a gas laser device according to a fourth embodiment of the present invention.

FIG. 5 is a schematic diagram showing a relationship between a laser housing and a heating oven of a gas laser device according to a fifth embodiment of the present invention.

FIG. 6 is a process diagram from assembly of the casing to shifting to steady operation in the first embodiment.

FIG. 7 is a process diagram from assembly of a housing to shifting to steady operation in a sixth embodiment.

FIG. 8 is a diagram showing a relationship between the number of times of passivation processing of the laser housing and the number of laser output halves in the present invention.

FIG. 9 is a schematic view showing a gas exhaust device in a laser housing of a conventional gas laser device.

FIG. 10 is a process diagram from assembly of a conventional laser housing to shifting to steady operation.

[Explanation of symbols]

 6 Laser Housing 7 Heating Jacket 8 Inlet 9 Outlet 10 Main Exhaust Pipe 11 Exhaust Valve 12 High Vacuum Exhaust Pump 16 Heating Piping 17 Mask Rossie's Heater 18 Halogen Lamp Heater 19 Tape Heater 20 Oven

Claims (3)

[Claims] 1. A laser housing of a gas laser device, wherein a gas is exhausted while heating the inside of a housing in a gas discharging step in a passivation process in which filling of a laser medium gas, laser oscillation, and discharging of a dirty gas are repeated. How to exhaust gas from the body. 2. A laser housing for a gas laser device, characterized in that a passage surrounding the laser housing is provided on the outer surface, and a heating medium is circulated in the passage to heat the inside of the housing. . 3. A laser housing of a gas laser device, wherein a heater is provided in the laser housing, and the inside of the housing is heated by the heater.