JPS62165383A - Excimer laser device - Google Patents

Abstract

PURPOSE:To facilitate obtaining an excimer laser device which is small in size and can maintain a constant halogen gas concentration for a very long time and can be operated easily by providing a halogen absorbing substance and a temperature control means near the halogen absorbing substance. CONSTITUTION:A control circuit 4 controls the temperature of a heater unit 3 to regulate the temperature of a halogen absorbing substance 2 so as to be the temperature instructed by a control unit 5. By putting the halogen absorbing substance 2 in medium of excimer laser, for instance in mixed gas of Kr, the and F2 and controlling its temperature, the partial pressure of the halogen gas in the laser gas can be regulated. Therefore, if the temperature corresponding to the halogen gas partial pressure defined by the halogen absorbing substance is instructed to the control circuit by the control unit 5, the halogen gas partial pressure of laser gas G in a laser chamber 1 can be maintained at a certain value.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field of the Invention) The present invention relates to an excimer laser device containing halogen gas as a laser medium, such as a rare gas halogen excimer laser device.

(Background of the Invention) In discharge-excited excimer lasers that use a mixed gas containing logen gas as a laser medium, as the number of oscillations increases, the gas deteriorates and the output decreases.
The laser gas needed to be replaced.

Figure 7 is a schematic diagram of the gas supply/discharge system of a conventional excimer laser. The laser beam oscillation mechanism is omitted. In this device, in order to replace the laser gas G in the laser chamber 1 due to deterioration of the gas, the following procedure had to be performed. First, valve 13
The chamber 1 is opened to discharge the laser gas G in the chamber 1, and then connected to a vacuum pump to evacuate the chamber 1 to below atmospheric pressure.

After exhausting the air, close the valve 13 and use a suitable pressure reducing valve.
The valves 15 and 14 connected so that the laser gas such as F, He, Kr, etc. in the gas cylinder GB is reduced to a predetermined pressure are opened and closed as appropriate, and a plurality of laser gases or a plurality of laser gases are injected into the laser chamber 1 in advance. A single laser gas mixed at a predetermined mixing ratio is introduced.

At this time, the mixing ratio of each laser gas was adjusted manually or by the control device 16 and central processing unit 17 as shown in FIG. 7 so that it became a predetermined ratio. With this method, laser oscillation is not possible during gas exchange. Therefore, the following method was considered. A part of the deteriorated laser gas G is discharged by opening valve 13, and the reduced amount of laser gas is discharged by opening valve 15 and 1.
4, the laser gas G in the chamber is adjusted to a predetermined mixing ratio and pressure. In some cases, the operation was carried out manually, or the control device 16 and central processing unit 17 were connected so that the laser output could be monitored and the laser gas exchanged automatically depending on the degree of decrease in the output. These devices require gas cylinders, valve discharge systems, etc., and have the drawback of being extremely complicated and large-sized. Furthermore, the latter method in which gas is exchanged during oscillation has the disadvantage that the laser output fluctuates each time gas exchange is performed, making it unsuitable for devices that require stable output.

Furthermore, since the deterioration of the gas is due to a decrease in the fluorine gas concentration, there is a method of directly supplying halogen gas into the laser chamber 1 from the halogen gas cylinder GB by manually operating the valve 18, as shown in FIG. According to this method, it is difficult to adjust the pressure of the gas supply system and operate the valve 18 to prevent excessive supply of gas into the chamber 1, and if halogen gas is supplied in excess, However, in order to adjust the gas mixture ratio to a predetermined value, it is necessary to perform other complicated operations such as introducing and exhausting the laser gas.

(Objective of the Invention) The present invention addresses the above-mentioned drawbacks of the conventional excimer laser device, namely, the inability to replace deteriorated laser gas without interfering with oscillation, and the fact that the device becomes large and complicated due to the use of cylinders, etc. The purpose of the present invention is to provide an excimer laser device that is small and easy to operate, capable of maintaining a constant halogen gas concentration for a very long time, and solving the problem of difficulty in valve operation.

(Example) Figure 1 shows an example of the present invention, in which the excimer is 1g.
A substance 2 capable of absorbing halogens such as +t5rz r += and a heater unit 3 for adjusting the temperature of the substance are attached. Here, a halo polymer material, ceramic, etc. can be used. A heater control circuit 4 that adjusts the heater unit 3 and a control unit 5 that controls the heater control circuit 4 are electrically connected to each other.

The control circuit 4 has a function of controlling the temperature of the heater unit 3 so that the temperature of the halogen storage material 2 reaches the temperature specified by the control unit 5. The heater unit 3 has a function of being able to generate a temperature range determined by the halogen storage material 2, and is made of the above-mentioned material that is resistant to corrosion against halogen gas and does not release impurities into the laser chamber. or has been subjected to a surface treatment such as plating that has such a function. The halogen storage material 2 is a material that reacts with the halogen and generates a halide when placed in a halogen atmosphere at an appropriate temperature and pressure.Generally, when the temperature is lowered or the pressure is increased, the halogen is stored. Conversely, halogens are released when the temperature is increased or the pressure is decreased.

In addition, this material can absorb the halogen gas in the laser gas by placing the exothermic generation storage material 2 when storing halogen in an excimer laser medium made of a mixed gas of Kr, He, and F2, and controlling the temperature of the medium. It is possible to adjust the partial pressure.

Therefore, the halogen gas partial pressure of the laser gas G in the laser chamber 1 can be maintained constant by using the control unit 5 to instruct the control circuit 4 to determine the temperature relative to the halogen gas partial pressure determined by the halogen storage material. It is possible. FIG. 2 shows a second embodiment, in which the halogen storage material 2 and the heater unit 3 are not placed in the chamber, but are housed in the external container 6 through the valve 7. In this embodiment, the partial pressure may be adjusted while the valve 7 is always open, or the partial pressure may be adjusted by opening and closing the valve as appropriate. With this method, it is also possible to replace a deteriorated unit such as the halogen storage material 2 by closing the valve 7 during laser oscillation and removing part or all of the external container 6. At this time, impurities such as air existing in the external container 6 are removed by a known method, for example, using a vacuum pump. The partial pressure of halogen gas in the laser gas can be controlled simply by specifying the temperature, but by using the following method, the amount of halogen released by the halogen storage material 2 can be controlled in response to changes in the amount of halogen gas in the chamber. can be done. FIG. 3 shows a third embodiment of the present invention, in which a laser beam output from a laser chamber 1 is partially reflected by a beam splitter 8 and enters an output light monitor 9. In FIG. The output light monitor 9 converts the laser light output into an electrical signal and inputs it to the control unit 5. The control unit 5 can detect a decrease in the output light and output an instruction to the control circuit 4 to increase the halogen gas concentration in the laser chamber 1.

Also, the method to monitor the output light is to use a beam splitter.
You can also use the following method instead. FIG. 4 shows a fourth embodiment of the present invention, in which a sensor 10 capable of measuring the halogen gas concentration or mixed gas pressure within the laser chamber 1 is provided within the laser chamber 1. The sensor 10
For example, a device that uses an optical sensor to measure the amount of light emitted when halogen and silane are mixed and reacted can be used.

The halogen gas concentration or pressure signal converted by the sensor 10 is input to the control unit 5, and the control unit 5 can output an instruction to the control circuit 4 to obtain an appropriate halogen gas concentration.

FIG. 5 shows a fifth embodiment of the present invention, in which a temperature sensor 11 is attached near the halogen storage material 2. Since the temperature of the halogen storage material 2 changes depending on the surrounding halogen partial pressure, the halogen concentration in the laser chamber 1 can be determined by measuring the temperature with the temperature sensor 11. Therefore, by connecting the output signal of the temperature sensor 11 to the control unit 5, an instruction can be output to the control circuit 4 so as to obtain an appropriate halogen gas concentration.

FIG. 6 shows an example of a sixth embodiment of the present invention, in which a discharge characteristic measuring device 12 for measuring voltage, current, or voltage/current is electrically connected to the main discharge electrode ME. As the discharge characteristic measuring device 12, for example, an oscilloscope or the like capable of outputting an input voltage or current waveform as a digital or analog signal can be used. The portion that supplies voltage to the main discharge electrode ME is omitted. Since the discharge characteristics change when the laser gas G deteriorates, the discharge characteristics are measured by the discharge characteristic measuring device 12 and output to the control unit 5. From this signal, the control unit 5 determines whether or not it exhibits predetermined discharge characteristics,
If it is off, adjust the halogen gas concentration to an appropriate level.
Instructions can be output to the control circuit 4.

The third to sixth embodiments described above have been described based on the embodiment shown in FIG. 1, but it goes without saying that they can all be similarly applied to the embodiment shown in FIG.

(Effects of the Invention) As described above, according to the present invention, the halogen gas reduced in the laser chamber can be automatically replenished, thereby stabilizing the excimer laser output light over a long period of time and increasing the gas life. There is an advantage. Furthermore, it does not require complicated valve operations like gas exchange.
Operation can be simplified.

Furthermore, since the time to respond to gas deterioration is quick, fluctuations in output can be reduced. Furthermore, the device of the present invention is much smaller than the gas supply system that uses commonly used gas cylinders, valves, etc., making it possible to miniaturize the excimer laser device and reducing the size of the gas supply system. Installation effort can also be reduced.

Furthermore, the embodiment shown in FIG. 2 and the method based thereon also have the advantage that the deteriorated fluorine absorbing material can be easily replaced and maintenance can be simplified.

[Brief explanation of drawings]

1 to 6 are schematic cross-sectional views of embodiments of the present invention, and 7.
FIG. 8 is a schematic cross-sectional view of a conventional example. (Explanation of symbols of main parts) G--Laser gas (laser medium) Mo----Laser output window Mr----Total reflection mirror ME-m-Main discharge electrode plate GB----Laser gas cylinder 1-------・Excimer laser chamber 2----
---Halogen storage material 3 -1--Heater unit 4 -1--Heater unit control circuit 5-
- Control unit 6 - Outer container 7.13.14.15.18, - Valve 8 - Beam splitter 9 - Output light monitor 10, l l -Temperature sensor 12-Discharge characteristic measuring device 16-=Pulp control device

Claims (1)

[Claims] 1. An excimer laser device using a mixed gas containing halogen gas as a laser medium, the excimer laser device comprising a halogen storage material and a temperature control means provided in the vicinity of the halogen storage material.