JPH045877A - Gas laser device - Google Patents

Abstract

PURPOSE:To obtain stable glow discharge even at the end sections of a main discharge electrode pair by mounting sections not fixed only by the specified times of length in the longitudinal direction of curved surface sections at both ends of anode discharging surfaces in support bars to chambers at both ends of an anode. CONSTITUTION:The discharging surfaces of an anode 12a are formed in curved surfaces only by a distance (x) in the longitudinal direction toward end faces respectively from points C1 and C2 at both end sections of the anode 12a. Support bars 21a and 21n at both end sections of the anode 12a are fixed at positions separate only by a distance L respectively from each end face of the anode. An excellent result is displayed between one and a half times and twice and a half times of the distance (x) by an experiment regarding the distance L in this case, and it is confirmed that twice is particularly favorable. The inhibition effect of the generation of arc discharge is weakened at both end face sections when L is less than one and a half times, and no glow discharge is generated at both end sections and power is reduced when L exceeds twice and a half times. Field strength in the longitudinal direction including both end sections of the anode is equalized, thus suppressing the generation of arc discharge, then acquiring stable glow discharge.

Description

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

<Prior Art> Excimer laser devices are attracting attention as light sources for photolithography, photoCVD, etc. as short-wavelength and high-output lasers. The internal structure of the chamber is
The figure shows a cross-sectional view in a direction perpendicular to the laser beam output direction.

Inside the laser chamber 11 filled with a medium gas, in addition to the main discharge electrode pair 12 consisting of an anode 12a and a cathode 12b facing each other, a pre-ionization electrode 13, a peaking capacitor 14, a cross flow fan 15, and a heat exchanger are installed. A container 16 etc. are arranged.

A peaking capacitor 14 is connected in series to the pre-ionization electrode 13, and the pre-ionization electrode 13 generates ultraviolet light by arc discharging prior to main discharge, ionizes the medium gas, and generates a voltage between the main discharge electrode pair 12. It plays a role in making the discharge more likely to become a glow discharge.

Further, the cross flow fan 15 is a gas circulation means for removing unstable gas generated between the main discharge electrode pair 12 due to the main discharge and feeding fresh gas between the main discharge electrode pair 12 before the next discharge. be. The heat exchanger 16 is provided to prevent the medium gas temperature from rising due to the thermal energy generated in the main discharge.

The cathode 12b of the main discharge electrode pair 12 is fixed to the chamber 11 via an insulator 20, and the high voltage power supplies H, V
, are connected. On the other hand, as shown in FIG. 3, the anode 12a is supported by a plurality of support rods 21a...21n arranged at equal intervals, and each of the support rods is a pillar. 22 (see FIG. 2) to the chamber 11, thereby forming a current circuit for causing discharge.

<Problems to be Solved by the Invention> By the way, the main discharge electrode pair 12 suppresses the concentration of electric field at the edges and the occurrence of arc discharge due to the shape effect, so that a uniform glow discharge occurs over the entire surface between the electrodes. , curved surfaces are provided on the edges of both the anode 12a and the cathode 12b so that the distance gradually becomes wider.

However, in the conventional support method as shown in FIG. 3, there is a problem in that arc discharge is likely to occur at the end of the electrode, partly because the gas flow rate by the cross flow fan 15 is slow.

The present invention has been made in view of these points, and an object of the present invention is to provide a discharge-excited gas laser device that can generate a stable glow discharge even at the ends of a pair of main discharge electrodes.

<Means for Solving the Problems> In order to achieve the above object, in the present invention, as shown in FIG. The support rod 2 is placed at a distance of 1.5 to 2.5 times the distance X from the position C, where the discharge surface becomes a curved surface to each end surface of the anode.
1a and 21n are not fixed.

<Operation> The reason why arc discharge occurs at the ends of the main discharge electrode pair is that the gas flow rate is slow in this part, and also because the electric field strength is uneven at both ends of the anode 12a.

By fixing the support rods 21a and 21n at both ends of the support rods 21a...21n of the anode 12a at positions that are within the center of the anode 12a by the distances described above from both ends of the anode 12a, the electric field strength of the anode 12a is increased. It was confirmed that the arc discharge became uniform and arc discharge was suppressed.

<Example> FIG. 1 is a side view (a) and a back view (b) showing the relationship between an anode 12a and its support rods 21a...21n in an example of the present invention. In this embodiment, other structures are the same as those shown in FIG. 2 described above, and a detailed explanation of these parts will be omitted.

The shape of the anode 12a itself is the same as that of the conventional one, and the discharge surface is curved by a distance X in the longitudinal direction from points CI and C2 at both ends of the anode 12a toward the respective end faces.

・This anode 12a is electrically and mechanically connected to the chamber 11 through a plurality of supports, frame rods 21a...21n, and columns 22...22 fixed to the respective support rods, as in the conventional case. However, the support rods 21a and 21na at both ends of the 77 node 12a are fixed at positions as far apart as possible from each end surface of the anode. This distance is twice the distance X mentioned above. The support rods between the support rods 21a and 21n at both ends are equally spaced from each other as in the conventional case.

According to the above embodiments of the present invention, it has been confirmed that the electric field strength of the anode 12a is substantially uniform between both end faces in the longitudinal direction, and a --like glow discharge can be obtained between the both end faces.

Here, regarding the distance, 1 of the distance X,
It was confirmed that good results were obtained between 5 times and 2.5 times, with 2 times being the most preferable.

When L is less than 1.5 times X, the effect of suppressing the occurrence of arc discharge at both end surfaces becomes weaker, and when it exceeds 2.5 times, no glow discharge occurs at both end surfaces. It turned out that the power was down.

(1) <Effects of the Invention> As explained above, according to the present invention, the support rods for the chamber at both ends of the anode are arranged such that the length in the longitudinal direction of the curved surfaces at both ends of the anode discharge surface is 1.5 to 2. By providing a portion that does not stick by 5 times, the electric field strength in the longitudinal direction including both ends of the anode is made uniform, so arc discharge does not occur at both ends of the main discharge electrode pair as in the conventional case. This suppresses the glow discharge and makes it possible to obtain stable glow discharge.

[Brief explanation of drawings]

FIG. 1 shows an anode 12a and a support rod 21a according to an embodiment of the present invention.
FIG. 2 is an explanatory diagram of the structure of a discharge-excited gas laser device to which the present invention is applied. FIG. 3 is an explanatory diagram showing the relationship between a conventional anode and a support rod. 11...Chamber 12...Main discharge electrode pair 12a...Anode 12b...Cathode 3...Preliminary ionization electrode 4...Peaking capacitor 5,...Cross flow fan 6...Heat exchange ~ device 0... Late body n... Support rod 2... Strut

Claims (1)

[Claims] A main discharge electrode pair consisting of an anode and a cathode facing each other is arranged in a chamber filled with a medium gas, and the anode side is connected to the chamber through a plurality of support rods, and the cathode side is connected to a high voltage power source. In a discharge-excited laser device connected to a current circuit to form a current circuit, 1 of the distance from both end faces of the anode to the position where the anode discharge surface becomes a curved surface at each end of the anode. A gas laser device characterized in that the support rod is not fixed by a distance of .5 to 2.5 times.