JPH04328887A - Excimer laser device - Google Patents

Abstract

PURPOSE:To restrain a streamer from occurring so as to enhance an excimer laser device in oscillation efficiency and to lessen electrodes in consumption by a method wherein a cathode electrode heating power supply which heats a cathode electrode is provided. CONSTITUTION:An anode electrode 1, a cathode electrode 2, a back electrode 3, and a dielectric layer 4 are enveloped in a laser tube charged with laser gas such as KrF or the like. A cathode electrode heating power supply 6 is provided outside the laser tube, and Joule heat is generated taking advantage of time resistance of the cathode electrode itself to heat the cathode electrode 2 before laser oscillation starts. That is, the cathode electrode 2 is heated enough by the cathode electrode heating power supply 6 before laser oscillation to be given a condition where hot electrons are easily emitted. By this setup, an excimer laser device which is free from streamer, high in oscillation efficiency, very small in electrode consumption, and long in service life can be obtained.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an excimer laser device having a unique electrode structure.

0002

[Prior Art] Fig. 4 shows, for example, the conventional excimer laser shown in Fig. 1.19(b), page 17 of ``Development of Excimer Laser and Its Application Techniques and Examples'' (authored by Shuntaro Watanabe; Oyo Gijutsu Publishing). FIG. 2 is a configuration diagram showing a laser device, in which (a) shows an electrode structure seen from the optical axis direction, and (b) shows an electrode structure seen from the lateral direction. In the figure, 1 is a mesh-like anode electrode,
2 is a cathode electrode that generates an excitation main discharge between it and the anode electrode 1, and the anode electrode 1 and the cathode electrode 2 constitute the main electrode. 3 is a back electrode that is electrically connected to the cathode electrode 2 and causes a corona pre-ionization discharge between the anode electrode 1; and 4 is a dielectric layer formed on the surface of the back electrode 3. 5 is a laser tube filled with laser gas such as KrF, and has an anode electrode 1 and a cathode electrode 2.
, a back electrode 3 and a dielectric layer 4 are housed therein. L is a laser beam generated by the main discharge for excitation.

[0003] SW is a switch such as a thyratron,
C1 is a charging capacitor for discharging inserted between the cathode electrode 2 and switch SW, and L is connected between the anode electrode 1 and cathode electrode 2 and used when charging the charging capacitor C1. The charging inductance C2 is a peaking capacitor connected in parallel with the charging inductance L.

Next, the operation of the conventional excimer laser device shown in FIG. 4 will be explained. First, the charging capacitor C1 is charged via the charging inductance L from a charging means (not shown). When the switch SW is turned on in this state, the charge in the charging capacitor C1 is transferred to the peaking capacitor C2, and a voltage rises between the anode electrode 1 and the back electrode 3 and between the anode electrode 1 and the cathode electrode 2.

[0005] As a result, a corona pre-ionization discharge occurs between the anode electrode 1 and the back electrode 3 via the dielectric layer 4. The pre-ionized electrons generated here reach the gap between the anode electrode 1 and the cathode electrode 2 through the gap between the mesh-like anode electrodes 1 and generate an exciting main discharge between the electrodes. The energy generated by this main discharge for excitation is amplified by a resonator (not shown) and output as laser light.

[0006]

[Problems to be Solved by the Invention] Since the conventional excimer laser device is constructed as described above, there is a limit to the number of initial electrons due to corona preionization, and the anode electrode 1
If the gap length between the cathode electrodes 2 (discharge gap length) is wide, the discharge will include streamers, resulting in problems such as lower oscillation efficiency and increased electrode wear.

The present invention was made in order to solve the above-mentioned problems, and aims to obtain a long-life excimer laser device that suppresses the generation of streamers, has high oscillation efficiency, and has extremely low electrode wear. purpose.

[0008]

[Means for Solving the Problems] An excimer laser device according to the present invention is characterized in that a cathode electrode heating power source is provided for heating the cathode electrode.

An excimer laser device according to another aspect of the present invention is characterized in that an electromagnetic wave generation source for irradiating electromagnetic waves with a shorter wavelength than UV light is provided on the surface of the cathode electrode.

0010

[Operation] In this invention, electron emission from the surface of the cathode electrode is promoted by heating the cathode electrode.

In another aspect of the present invention, electron emission from the cathode surface is promoted by irradiating the cathode surface with electromagnetic waves having a shorter wavelength than UV light.

0012

[Example] Example 1. Embodiment 1 of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram showing Embodiment 1 of the present invention, in which (a) shows the electrode structure as seen from the optical axis direction, and (b) shows the structure of the electrode as seen from the optical axis direction.
shows the electrode structure viewed from the lateral direction. In FIG. 1, 1 to
4, SW, C1, L and C2 are the same as the conventional ones. Although not shown in FIG. 1, the anode electrode 1,
The cathode electrode 2, the back electrode 3, and the dielectric layer 4 are housed in a laser tube filled with a laser gas such as KrF, as in the conventional case.

Reference numeral 6 denotes a power source for heating the cathode electrode provided outside the laser tube, which heats the cathode electrode 2 even before laser oscillation by generating Joule heat using the resistance of the cathode electrode 2 itself. .

Next, the operation of the first embodiment shown in FIG. 1 will be explained. First, before laser oscillation, the cathode electrode 2 is sufficiently heated by the cathode electrode heating power source 6 to create conditions that facilitate the emission of thermoelectrons. The subsequent operation is almost the same as the conventional one, but the pre-ionized electrons are transferred to the anode electrode 1.
When a main discharge for excitation is generated between the electrodes of the cathode electrode 2, thermoelectrons are easily emitted from the cathode electrode 2, and the generation of streamers is suppressed even when the gap between the anode electrode 1 and the cathode electrode 2 is wide. be done.

Example 2. FIG. 2 is a configuration diagram showing a second embodiment of the present invention, in which (a) shows an electrode structure seen from the optical axis direction;
(b) shows the electrode structure seen from the lateral direction, 1 to 4, 6,
SW, C1, L and C2 are the same as in Example 1. Reference numeral 7 denotes a heater embedded near the surface inside the cathode electrode 2, and in this case, the cathode electrode 2 can be heated more efficiently with less electric power than in the first embodiment.

Example 3. FIG. 3 is a configuration diagram showing Embodiment 3 of the present invention, in which (a) shows the electrode structure seen from the optical axis direction;
(b) shows the electrode structure viewed from the lateral direction, 1 to 5, SW
, C1, L and C2 are the same as the conventional ones. Numeral 8 denotes a plurality of transmission windows provided along the optical axis direction on both sides of the outer surface of the laser tube 5, and numeral 9 denotes UV light irradiated through the transmission window 8. 10 is a UV light source that irradiates UV light 9, and constitutes an electromagnetic wave generation source.

In Examples 1 and 2, electrons were easily emitted from the surface of the cathode electrode 2 by heating the cathode electrode 2, but in this Example 3
Now, by irradiating the UV light 9 from the UV light source 10, electrons are easily emitted. In addition, here U
Although V light 9 is used, electromagnetic waves having a shorter wavelength than UV light, such as X-rays, may also be used.

[0018]

As described above, according to the present invention, the cathode of the main electrode is heated to emit thermoelectrons, so the oscillation efficiency is high without a streamer, and the electrode wear is extremely low, resulting in a long life. This has the advantage of being an excimer laser device.

According to another invention of the present invention, since electrons are emitted by irradiating the cathode surface of the main electrode with UV light, the oscillation efficiency is high without streamers, and electrode wear is extremely low. This has the effect of providing an excimer laser device with a long lifespan.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram showing a first embodiment of the present invention.

FIG. 2 is a configuration diagram showing a second embodiment of the present invention.

FIG. 3 is a configuration diagram showing a third embodiment of the present invention.

FIG. 4 is a configuration diagram showing a conventional excimer laser device.

[Explanation of symbols]

1 Anode electrode 2 Cathode electrode 6　　　　Cathode electrode heating power supply 9. UV light or X-rays 10 UV light source

Claims (2)

[Claims] 1. An excimer laser device having an anode electrode and a cathode electrode for forming a main discharge for excitation, characterized in that the excimer laser device is provided with a cathode electrode heating power source for heating the cathode electrode. 2. In an excimer laser device having an anode electrode and a cathode electrode for forming a main discharge for excitation, an electromagnetic wave generation source for irradiating the surface of the cathode electrode with short wavelength electromagnetic waves longer than UV light is provided. Features of excimer laser device.