JPH0716049B2 - Gas laser equipment - Google Patents

Description

The present invention relates to a discharge excitation type gas laser device such as an excimer laser device.

<Prior Art> An excimer laser device is attracting attention as a light source of short wavelength and high output as a light source for photolithography, photo-CVD, etc. A typical internal chamber structure is shown in FIG. 2 in a sectional view in a direction orthogonal to the laser light output direction.

In the laser chamber 11 filled with the medium gas, in addition to the main discharge electrode pair 12 in which the anode 12a and the cathode 12b face each other, the preliminary ionization electrode 13, the peaking capacitor 14, the cross flow fan 15, and the heat exchange. A container 16 and the like are provided.

A peaking capacitor 14 is connected in series to the preionization electrode 13, and the preionization electrode 13 generates ultraviolet light by arc discharge prior to the main discharge, and ionizes the medium gas between the main discharge electrode pair 12. The above-mentioned discharge plays a role of facilitating glow discharge.

Further, the cross flow fan 15 is a gas circulation means for removing the unstable gas between the main discharge electrode pair 12 generated by the main discharge and sending fresh gas between the main discharge electrode pair 12 until the next discharge. is there. The heat exchanger 16 is provided to prevent the temperature of the medium gas from rising due to the heat energy generated by the main discharge.

The cathode 12b of the main discharge electrode pair 12 is fixed to the chamber 11 via the insulator 20, and is connected to the high voltage power supply HV. On the other hand, the anode 12a is supported by a plurality of support rods 21a ... 21n arranged at equal intervals as shown in the back surface (back surface of the discharge surface) of FIG.
It is fixed to the chamber 11 via 22 (see FIG. 2), 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 occurrence of arc discharge due to the concentration of the electric field and the shape effect at the edge portion thereof so that a uniform glow discharge is generated over the entire surface between the electrodes. The curved surfaces are provided at the edges of both the anode 12a and the cathode 12b so that the intervals gradually increase.

However, the conventional supporting method as shown in FIG. 3 has a problem that arc discharge is still likely to occur because the gas flow velocity by the cross flow fan 15 is low at the electrode end.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a discharge excitation type gas laser device that can obtain stable glow discharge even at the end portions of the main discharge electrode pair.

<Means for Solving the Problems> In order to achieve the above object, in the present invention, as shown in FIG. 1 corresponding to the embodiment, from both end surfaces of the anode 12a,
The distance x from each end face of the anode 12a to each end face of the anode C ₁ and C ₂ where the anode discharge surface is a curved surface.
The support rods 21a and 21n are not fixed by the distance L which is 1.5 to 2.5 times as large as

<Operation> The reason why arc discharge occurs at the end of the main discharge electrode pair is that the gas flow velocity is slow in this part
This is because the electric field strength is non-uniform at both ends of 12a.

Of the support rods 21a ... 21n of the anode 12a, those at both ends 21a
For 21n, the above distance L from both ends of the anode 12a
It was confirmed that the electric field strength of the anode 12a becomes uniform and the arc discharge is suppressed by sticking to the positions respectively entering the center side.

<Embodiment> FIG. 1 shows an anode 12a and its supporting rod 2 according to an embodiment of the present invention.
Side view (a) and back view (b) showing the relationship of 1a ... 21n
Is. In addition, in this embodiment, the other structures are the same as those shown in FIG. 2 described above, and detailed description thereof 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 from the points C ₁ and C ₂ at both ends of the anode 12a toward the end surfaces by a distance x in the longitudinal direction.

This anode 12a has a plurality of support rods 21a ... 21 as in the conventional case.
n is electrically and mechanically connected to the chamber 11 via columns 22 ... 22 fixed to the respective support rods. The support rods 21a and 21n at both ends of the anode 12a are end faces of the anode. Are fixed at positions separated from each other by a distance L. This distance L is twice the distance x described above. Then, the support rods between the support rods 21a and 21n at both ends are equally arranged as in the conventional case.

According to the above-described examples of the present invention, it was confirmed that the electric field strength of the anode 12a was substantially uniform in the longitudinal direction between both end faces, and uniform glow discharge was obtained between the both end faces.

Here, as for the distance L, the distance x is 1.5
It was confirmed that good results were obtained in the range of 2 times to 2.5 times, and 2 times was particularly preferable. Then, when L is less than 1.5 times x, the effect of suppressing the occurrence of arc discharge on both end faces becomes weak, and when it exceeds 2.5 times, glow discharge also ceases on both end faces, and both are found to be powered down. did.

<Effects of the Invention> As described above, according to the present invention, the support rods to the chamber at both ends of the anode are fixed by 1.5 to 2.5 times the length in the longitudinal direction of the curved surface portions at both ends of the anode discharge surface. By providing the non-existing portion, the electric field strength in the longitudinal direction including the both ends of the anode is made uniform, so that the occurrence of arc discharge at both ends of the main discharge electrode pair is suppressed and stable as in the conventional case. Glow discharge came to be obtained.

[Brief description of drawings]

FIG. 1 shows the anode 12a and supporting rods 21a to 21n of the embodiment of the present invention.
2 is a structural explanatory view of a discharge excitation type gas laser device to which the present invention is applied, and FIG. 3 is an explanatory view showing a conventional relationship between an anode and a support rod. 11 …… Chamber 12 …… Main discharge electrode pair 12a …… Anode 12b …… Cathode 13 …… Preliminary ionization electrode 14 …… Peaking capacitor 15 …… Cross flow fan 16 …… Heat exchanger 20 …… Insulator 21a… 21n …… Support rod 22 …… Post

Claims (1)

[Claims] 1. A main discharge electrode pair, in which an anode and a cathode are opposed to each other, is arranged in a chamber filled with a medium gas, and the anode side is connected to the chamber by a plurality of support rods. In a discharge excitation type laser device in which a cathode side is connected to a high voltage power source and a current circuit is formed, from both end faces of the anode, from the position where the anode discharge face is curved at each end of the anode, each end face of the anode A gas laser device characterized in that the supporting rod is not fixed for a distance of 1.5 to 2.5 times the distance to.