JPH04196373A - Pulse laser device - Google Patents

Abstract

PURPOSE:To lessen a main discharge circuit in inductance so as to obtain a discharge of high excitation intensity by a method wherein a laser chamber is formed in a dual structure, only a discharge part is housed in an inner chamber, and a pre-ionization peaking capacitor is provided inside an outer chamber close to the outside of the inner chamber. CONSTITUTION:A laser chamber is made to have a dual structure, only a discharge section is housed in an inner chamber 20a, and a pre-ionization peaking capacitor 5 is provided inside an outer chamber 20b close to the outside of the inner chamber 20a. As mentioned above, the laser chamber is formed in a dual structure, whereby the inner chamber 20a which contains a main discharge circuit can be formed thin-walled, and even if the peaking capacitor 5 is provided outside the inner chamber 20a, it can be set close to a main charge section 9. By this setup, the main discharge circuit 9 can be lessened in inductance, and a discharge high in excitation intensity can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention (Industrial Field of Application) The present invention relates to a pulsed laser device that has been improved so as to be able to obtain discharge with high excitation intensity.

(Prior Art) TEMA-C02 lasers, excimer lasers, and the like are widely used as pulse laser devices that perform laser operations by enclosing a laser gas at a pressure lower than atmospheric pressure. An example of a typical structure of such a pulse laser device is shown in FIG.

Note that FIG. 2 shows the power supply circuit, discharge section, and laser chamber of the pulse laser device. Further, the configuration of this power supply circuit uses a capacitance transfer type circuit in combination with an LC inverting circuit, and is characterized by applying a high voltage to the discharge section.

In FIG. 2, the high voltage applied from the high voltage section 1 is
Two capacitors 2 (capacitance C,) are charged using the inductance 3 (Lc). Next, by operating the thyratron 4, which is a switching element, the energy charged in the capacitor 2 is transferred to the peaking capacitor 5 (capacitance C2). At this time, since small gaps 7 with an interval of 1 to 2 mm are provided in series in the charging circuit of the peaking capacitor 5, arc discharge occurs between the gaps when charging the peaking capacitor 5, and UV
By generating light, the space between the two main discharge electrodes 6 is pre-ionized 8 prior to the main discharge. Then, when the charging voltage of the peaking capacitor 5 becomes sufficiently high and the voltage between the main discharge electrodes 6 reaches the discharge breakdown voltage, the capacitance C2, the inductance in the main discharge circuit, and the two main discharge electrodes 6 disposed opposite to each other increase. A pulse discharge occurs in the LCR circuit of the discharge resistor Rd between the two, and the excimer laser gas is excited.

The main discharge circuit section 9 that performs the pulse discharge is disposed inside a laser chamber 10, and the inside is filled with laser gas at high pressure (>1 atmosphere).

In order to withstand this high gas pressure, the laser chamber 10 is made of thick stainless steel, aluminum, or the like. Further, this laser chamber 10 is provided with a high voltage introduction terminal 11 for energy transfer from the capacitor 2 to the main discharge circuit section 9. Furthermore, a peaking capacitor 5 is also housed within the laser chamber 10 in order to reduce inductance in the main discharge circuit.

(Problems to be Solved by the Invention) However, the conventional pulse laser device as described above has the following problems to be solved. That is,
As shown in FIG. 2, when the peaking capacitor 5 is housed in the laser chamber 10 together with the main discharge circuit section 9,
The peaking capacitor 5 will be placed in a laser gas atmosphere.

In this case, depending on the type of laser gas such as excimer laser gas containing halogen gas, the peaking capacitor may be corroded, resulting in a drawback that the life of the pulse laser device is significantly shortened.

To solve this drawback, the peaking capacitor 5
However, if the peak-ink capacitor 5 is placed outside the laser chamber 10, the inductance of the main discharge circuit becomes large due to the large thickness of the laser chamber 10, resulting in a high excitation intensity. A problem has arisen in that discharge cannot be obtained and efficient laser excitation cannot be performed.

The present invention was proposed in order to eliminate the above-mentioned drawbacks of the prior art, and its purpose is to reduce the inductance of the main discharge circuit and achieve high efficiency by which discharge with high excitation intensity can be obtained. The purpose of the present invention is to provide a pulse laser device.

[Configuration of the Invention] (Means for Solving the Problems) The present invention includes a laser chamber that holds a laser gas,
In a pulse laser device consisting of a discharge part that performs a laser action and a power supply circuit that applies a pulse voltage to the discharge part, the laser chamber has a double structure, with only the discharge part housed in the inner chamber, and the outer chamber The device is characterized in that a peaking capacitor for pre-ionization is disposed inside the chamber near the outside of the internal chamber.

(Function) According to the pulse laser device of the present invention having the above configuration, by making the laser chamber a double structure, the thickness of the internal chamber containing the main discharge circuit can be reduced, and the peaking capacitor can be connected internally. Even if the capacitor is disposed outside the chamber, the distance between the peaking capacitor and the main discharge section can be brought closer, so that the inductance of the main discharge circuit can be reduced.

(Example) Hereinafter, an example of the present invention will be specifically described based on FIG. Note that the same parts 4 as in the conventional type shown in FIG. 2 are given the same reference numerals, and the description thereof will be omitted.

In this embodiment, as shown in FIG. 1, the laser chamber is divided into an inner chamber 20a and an outer chamber 20b
It is said to have a double structure consisting of.

In the internal chamber 20a, a main discharge circuit section 9 is provided.
only is stored. On the other hand, in the external chamber 20b, a portion other than the high voltage section 1 and a peaking capacitor 5 of a power supply circuit using both a capacitance transfer type circuit and an LC inversion circuit are housed.

Here, the peaking capacitor 5 is connected to the internal chamber 20.
The reason for disposing it outside of a is to prevent corrosion caused by laser gas.

The internal chamber 20a is provided with an internal high voltage introduction terminal 21a for energy transfer from the capacitor 2 to the main discharge circuit section 9, and the external chamber 20b is provided with an internal high voltage introduction terminal 21a for energy transfer from the high voltage section 1 to the power supply circuit section. An external high voltage introduction terminal 21b is provided for energy transfer.

The pulse laser device of this example having such a configuration is as follows:
It works as described below. That is, the high voltage introduced into the external chamber 20b from the high voltage section 1 via the external high voltage introduction terminal 21b is charged into the two capacitors 2 using the inductance 3. Next, by operating the thyratron 4, which is a switching element, the energy charged in the capacitor 2 is transferred to the peaking capacitor 5 and the internal high voltage introduction terminal 21H that injects a high voltage into the internal chamber 20a.

At this time, in the charging circuit of the peaking capacitor 5, small gas pockets with an interval of 1 to 2 mm are provided in series, so when charging the peaking capacitor 5, arc discharge is performed between the gaps and UV light is generated. , the space between the two main discharge electrodes 6 is pre-ionized 8 prior to the main discharge.

Then, when the charging voltage of the peaking capacitor 5 becomes sufficiently high and the voltage between the main discharge electrodes 6 reaches the discharge breakdown voltage, the capacitance C2, the inductance in the main discharge circuit, and the two main discharge electrodes 6 disposed opposite to each other increase. A pulse discharge occurs in the LCR circuit of the discharge resistor Rd between the two, and the excimer laser gas in the internal chamber 20a is excited.

In this case, the internal pressure Pin of the internal chamber 20a and the internal pressure Pout of the external chamber 20b are set as Pin≧Pou
By making them close within a range that satisfies the relationship t≧latm, the pressure-resistant design of the internal chamber 20a can be simplified compared to the pressure-resistant design of the external chamber 20b. I wanted to,
Since it is possible to reduce the thickness of the metal material constituting the internal chamber 20a, the peaking capacitor 5 and the main discharge circuit section 9 disposed outside the internal chamber 20a can be reduced.
You can bring the distance closer. As a result, the stray inductance within the main discharge circuit section 9 is significantly reduced, and discharge with high excitation intensity can be realized.

In this way, according to this embodiment, the laser chamber has a double structure, and the main discharge circuit section is housed in the inner chamber.
By arranging the peaking capacitor outside the inner chamber, the thickness of the inner chamber can be reduced, thereby significantly reducing the stray inductance in the main discharge circuit and obtaining a discharge with high excitation intensity.

Although the above-mentioned embodiments have been described with reference to a rare gas-halide excimer laser, the present invention uses a high-pressure laser gas above atmospheric pressure and performs a laser operation by pulse discharge excitation, similar to an excimer laser.
It can also be applied to lasers, F2 lasers, etc.

[Effects of the Invention] As explained above, according to the present invention, the laser chamber has a double structure, and only the discharge part is housed in the inner chamber, and the discharge part is housed inside the outer chamber and near the outside of the inner chamber. By providing a peaking capacitor for pre-ionization, it is possible to reduce the inductance of the main discharge circuit and provide a highly efficient pulsed laser device that can obtain discharge with high excitation intensity.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of a pulse laser device of the present invention, and FIG. 2 is a block diagram showing an example of a conventional pulse laser device. ]... High voltage section, 2... Capacitor, 3... Inductance, 4... Thyratron, 5... Peaking capacitor, 6... Main discharge electrode, 7... Small gap, 80.
. Preliminary ionization, 9... Main discharge circuit section, 10... Laser chamber, 11... High voltage introduction terminal, 20a... Internal chamber, 20b... External chamber, 21a...
・Internal high voltage introduction terminal, 21b...External high voltage introduction terminal.

Claims (1)

[Scope of Claims] A pulse laser device comprising a laser chamber that holds a laser gas, a discharge section that performs a laser action, and a power supply circuit that applies a pulse voltage to the discharge section, wherein the laser chamber has a double structure, and an internal chamber 1. A pulse laser device, wherein only the discharge section is housed inside the external chamber, and a peaking capacitor for preliminary ionization is disposed inside the external chamber and near the outside of the internal chamber.