JPH02130989A - Halogen excimer laser device - Google Patents

Abstract

PURPOSE:To restrain the exhaustion of electrodes by a method wherein the content of impurities reacting to halogen gas or halogen compound gas in the surface layer parts of electrodes to produce a low boiling point compound is specified not to exceed specific percentage. CONSTITUTION:C, Si, S etc., as impurities contained in electrodes 1, 2 comprising Ni which react to fluorine in mixed gas to produce a low boiling point compound are removed down to the content of 0.01%. The said impurities are removed in the process wherein the electrodes 1, 2, after reduction in hydrogen atmosphere, are oxidized in oxygen atmosphere and further reduced again in hydrogen atmosphere later. When the electrodes 1, 2 are thick, the purpose can be achieved if only the impurity in the surface layer parts 14, 24 are removed. Through these procedures, the production of the low boiling point compound can be restricted thereby restraining the exhaustion of the electrode 1, 2.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is applicable to a wide range of industrial application fields such as the semiconductor industry and chemical industry, the medical field, and the energy field such as laser nuclear fusion. The present invention relates to a halogen excimer laser device that can be used.

[Prior art and problems to be solved by the invention] An excimer laser is an ultraviolet laser with an oscillation wavelength of 0.1 to 0.4 nm, and an excimer laser device for obtaining this is an Ar
+ to r, inert gas such as Xe, Ft, Nh.

Eximer laser is generated by generating a high-energy laser active medium such as ArF, KrF+ It is designed to cause oscillation. The lifespan factors of this excimer laser device include deterioration of the laser gas, deterioration of the laser reflector, deterioration of the switching element, deterioration of the main capacitor, deterioration of pre-ionization, etc. be able to.

Efforts have been made to extend the life of each of these devices. Further, although excimer laser devices are normally operated in a sealed tube manner, halogen gas has high chemical reactivity, so chemical reactions at the electrodes are significant, resulting in deterioration of the electrodes. This deterioration of the electrode is also one of the factors that determines the life of the excimer laser device, and it is desired to solve this problem and extend the life of the electrode.

Furthermore, in an excimer laser device, a high voltage is applied between two opposing electrodes to obtain a transverse discharge in which the direction of the current is perpendicular to the laser optical axis. This discharge has a rise time of 1
0 ns, and the pulse width is usually about 100 ns or less, so the electric field is If it is uniform, the discharge will not be localized even if the electrode has a continuous structure, and a negative-like discharge can be obtained.

If the electrode were an infinitely wide flat plate, the electric field would be uniform, but
Actual electrodes have only a finite extent, so even if a voltage is applied between the plates, a -like electric field cannot be obtained. - Electromagnetic calculations are required to obtain a similar electric field, and in the past the Rogowski electrode shape was considered optimal, and currently the Chang electrode shape is considered optimal, and these mathematically expressed electrode shapes are manufactured using NG machine tools. .

FIG. 4(a) shows a cross section of such an electrode shape,
For example, the surface layer 11.21 is coated with Ni, and the inner layer 12.21 is coated with Ni.
At 22, a cathode side electrode 1 and an anode side electrode 2 made of a Kovar alloy are provided facing each other and separated by a predetermined distance.

As shown in FIG. 4(a), immediately after the pulse discharge starts between the picture electrodes 1 and 2, the picture electrodes l.

The surface of 2 is flush with no depressions. However, picture electrode 1.2
If the discharge in between continues, as shown in Fig. 4 (bl),
During discharge, the center of the surface layer 11 of the electrode 1 reacts with the mixed gas present between the electrodes 1 and 2 to form fluoride (a low boiling point product).
, the surface layer 11 of the electrode 1 gradually becomes depressed 13
and deformation. At this time, the distance between the electrodes has increased at the center of the electrode 1, and the actual distance between the ends of the electrodes 1 and 2 is smaller (as a result, the discharge is concentrated at these ends. There were problems in that the uniformity of the discharge over the entire electrode surface was lost and the output of the laser was reduced.

The present invention has been made in view of the above problems, and aims to sufficiently remove impurities that react with halogen gas or halogen compound gas in a mixed gas to produce low-boiling point products from the constituent materials of the electrode. An object of the present invention is to provide a halogen excimer laser device that can suppress electrode consumption, can be used for a long time without replacing the electrodes, and does not require frequent disassembly of the device to replace the electrodes. It is said that

[Means to solve the problem]

In order to achieve the above object, the present invention provides that the amount of impurities that react with halogen gas or halogen compound residue in a mixed gas of an inert gas and halogen gas or halogen compound gas to produce a low boiling point product is reduced at least on the surface. 0.01 in parts
% or less.

[Effect]

As described above, the present invention reduces the amount of impurities that react with the halogen gas or halogen compound gas in the mixed gas at least in the surface layer of the electrode to form low-boiling point compounds to 0.01% or less, thereby reducing the amount of impurities during pulse discharge. The amount of low-boiling products generated is reduced, and electrode wear is suppressed.

〔Example〕

Embodiments of the halogen excimer laser device according to the present invention shown in the drawings will be described below.

FIG. 1 is a schematic cross-sectional view showing an electrode of a halogen excimer laser device according to the present invention.

This halogen excimer laser device has 8r, Kr+X
Inert gas such as e and Ft, NF3. CI□, HC
Eximer laser is generated by pulse-discharging the cathode and anode electrodes 1 and 2 in a mixed gas with a halogen gas such as I or a halogen compound gas to generate a high-energy laser active medium such as ^rp, KrP, XeC1, XeF, etc. It is configured to oscillate.

In the present invention, the electrode 1 made of, for example, Ni
．． C1Si, S, etc., which are impurities contained in fluorine and react with fluorine in the mixed gas to produce low-boiling compounds, are removed to suppress their content to 0.01% or less.

Removal of c, St, S, etc. from electrodes 1 and 2 made of Ni is performed by removing electrodes 1 and 2 made of Ni. This is done by reducing 2 in a hydrogen atmosphere, oxidizing it in an oxygen atmosphere, and then further reducing it in a hydrogen atmosphere. If the electrodes 1 and 2 are thick, it will take a long time to remove C, Si, S, etc. from the entire electrodes 1 and 2, so the surface layer of the electrodes 1 and 2 will be removed as shown in Figure 1. C, Si of only part 14.24 (thickness is e.g. l, am)
, S, etc. are removed.

As described above, by removing C, Si, S, etc. in the electrode 1.2 and suppressing the content to 0.01% or less, the generation of low boiling point products is reduced during pulse discharge. It is possible to suppress wear and tear on the electrodes 1.2,
I can do it.

Figure 2 (a) and (b) show 0.02% C and 0 Si.
．． This is an X-ray enlarged photograph of sample A of the electrode containing 0.08%.
Figures (a) and (b) are enlarged BOX-ray photographs of a sample of an electrode containing 0.06% Si. In addition, Fig. 2 (a) and Fig. 3 (
a) is 100x magnification, Fig. 2(b), Fig. 3 (bl is 20x
Each photograph was taken at 0x magnification. Table 1 shows the component values and boiling points of fluorides for each of Samples A and B.

Comparing Table 1 Figures 2(a), (b) and Figures 3(al, (bl), Sample B in Figures 3(a), (b) is different from Figure 2(a), (b). ) It can be seen that the surface unevenness of the sample is smaller than that of sample A. This is because the amount of C and SiO contained in sample B is smaller than that of sample A.
It is thought that because there are fewer grains, the surface is less uneven. Therefore, since the content of impurities such as C, Si, and S in the electrode in the device of the present invention is 0.01% or less, which is lower than that in Sample B, the unevenness on the surface of the electrode is further reduced. Generally, to remove the electrode, C and Si are removed through a process of reducing in a hydrogen atmosphere, oxidizing in an oxygen atmosphere, and then further reducing in a hydrogen atmosphere.

In the above embodiment, fluorine gas was used as a component of the mixed gas and Ni was used as a constituent material of the electrode 1.2. However, the constituent material of the electrode 1.2 may be, for example, CO, etc. In the case where the main component does not produce low-boiling fluoride, it is also possible to use the constituent material from which impurities have been removed.

〔Effect of the invention〕

According to the present invention, as described above, the amount of impurities that react with the halogen gas or halogen compound gas in the mixed gas in at least the surface layer of the electrode to produce low-boiling point products is reduced to 0.01% or less. , it is possible to reduce the generation of low-boiling point products during pulse discharge, it is possible to suppress the wear of the electrodes, it can be used for a long time without replacing the electrodes, and there is no need for frequent maintenance. It has the following effects.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view of an electrode in an embodiment of a halogen excimer laser device according to the present invention, FIG. 2(a),
(b) is an X-ray enlarged photograph of the surface of the electrode during pulse discharge in the halogen excimer laser device of the present invention;
), (b) are X-ray enlarged photographs of the surface of the electrode during pulse discharge in a conventional halogen excimer laser device, and FIGS. 4(a) and (b) are explanatory diagrams showing the electrodes of a conventional halogen excimer laser device. be. (2), 2... Electrodes In the drawings, the same reference numerals indicate the same or corresponding parts. Agent Masu Oiwa Yumi 1 Closed Figure 2 (a) (b) Nemon

Claims (1)

[Claims] 1. In a halogen excimer laser device equipped with an electrode to be pulse-discharged in a mixed gas of an inert gas and a halogen gas or a halogen compound gas, impurities that react with the halogen gas or halogen compound gas to produce low-boiling point products. A halogen excimer laser device, wherein the amount of the electrode is 0.01% or less at least in a surface layer portion of the electrode.