JPH0726855Y2 - Excimer laser device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an excimer laser device, and more particularly to an ultraviolet light preionization type excimer laser device.

<Prior Art> In a discharge excitation excimer laser, a capacitance transfer type circuit shown by an equivalent circuit in FIG. 5 is generally used as an excitation circuit. The operation of this circuit is as follows. The switch S such as a thyratron is turned off, the capacitor C ₁ is charged to a high voltage by the high voltage source HV, and the switch S is turned on. As a result, the electric charge stored in the capacitor C ₁ moves to the peaking capacitor C ₂ . This charge transfer increases the charging voltage of the peaking capacitor C ₂ , but when this voltage reaches the discharge start voltage between the main electrode pair E _d , pulse discharge occurs during this period, and the laser gas in the laser chamber 50 Are excited to cause laser oscillation.

The above is the basic operation of the excitation circuit. In the excimer laser, the laser gas pressure is kept at a relatively high pressure of 2 to 3 atmospheres. To generate a uniform glow discharge as the main discharge under such an atmosphere, It is necessary to ionize the gas in the discharge area prior to the main discharge, that is, to perform preionization. Therefore, normally, an electrode pair (pin electrode pair) that causes a spark is arranged in the vicinity of the main electrode pair E _d in the laser chamber 50, and a spark is generated between the pin electrode pair before the main discharge, The ultraviolet light generated at that time pre-ionizes the gas in the main discharge region.

Without separately providing an excitation circuit for this preionization,
The circuit shown in FIG. 5 also serves as an automatic preionization type, which is intended to automatically cause preionization during the main discharge operation, and is used in most commercially available lasers. It is a type. The equivalent circuit is shown in FIG. In the figure, E _p is a pin electrode pair for preionization.

By the way, in the excimer laser, since the lifetime of the upper level of laser transition is extremely short, a steep discharge, that is, a discharge with a high voltage having a fast rise is required in order to efficiently excite the gas. In the circuit shown in FIG. 6, in order to apply a fast rising voltage between the main electrode pair E _d, it is necessary to reduce the inductance of the discharge loop (the loop composed of C ₂ , E _p , and E _d ). is there. Actually, some measures are taken to shorten the path of current flow in this discharge loop. Therefore, set the peaking capacitor C ₂ to the main electrode pair.
This peaking capacitor C ₂ may be placed in the laser chamber to approach E _d . This is called a laser with a built-in capacitor.

FIG. 7 is a block diagram showing the internal structure of the chamber and the electric circuit of a conventional laser with a built-in capacitor.

Since the excimer laser is a pulsed laser, it is necessary to shorten the repetition cycle of oscillation in order to obtain a high average output. In this case, it is necessary to supply fresh gas between the main electrode pair E _d for each shot. This is because the impurities and negative ions generated by the discharge make the discharge unstable. That is, these cause the main discharge to be arc discharge, and the laser oscillation becomes unstable. Therefore, as shown in FIG. 7, a fan is usually installed in the laser chamber 50.
51 is arranged to circulate gas at high speed. Reference numeral 52 is a heat exchanger for cooling the gas.

<Problems to be Solved by the Invention> In the conventional capacitor built-in type ultraviolet light preionization type discharge excitation excimer laser shown in FIG. 7, the preionization pin electrode pair is used.
Since E _p ... E _p is arranged in the gas flow path, it is an obstacle to obtaining a high-speed gas flow. Further, the peaking capacitors C ₂ ... C ₂ are often arranged on the anode side as shown in the figure, and this is also likely to be an obstacle to the gas flow. A high-speed gas flow is required to increase the repetition frequency of oscillation, but due to the above-mentioned obstacles, it is difficult to increase the gas flow speed, and there is a problem that high-repetition oscillation is difficult. In other words, in order to increase the gas flow speed in order to increase the oscillation repetition frequency, a large fan and a large capacity motor for driving the fan are required.

<Means for Solving Problems> The present invention has been made to solve the above problems, and its configuration will be described with reference to FIG. 1 corresponding to the embodiment. The cathode E _dc side of the pair E _d is arranged close to the wall body (for example, the flange portion 12) of the laser chamber 1, and the preionization electrode pair E _p and the peaking capacitor C ₂ are arranged on the cathode E _dc side of the main electrode pair E _d. And the peaking capacitor C ₂ is supported on the wall of the laser chamber 1 (for example, the flange portion 12), and the preionization electrode pair E _p supplies one of the charges to the gas flow by the fan 2. It is characterized in that the plate-shaped electrode E _p1 is arranged in a guideable direction and the other is composed of a plurality of pin-shaped electrodes E _pi .

<Operation> The gas flow by the fan 2 is guided by the plate electrode E _pL and guided between the main electrode pair E _d . The cathode E _dc side of the main electrode pair E _d, which is arranged close to the wall 12 of the laser chamber 1 and placed close preionization electrode pair E _p and peaking capacitor C _2, wall 12 a peaking capacitor C ₂ By means of bearings in the laser chamber 1 there is no obstruction to the gas flow introduced between the main electrode pair E _d , and this gas flow is therefore
It has a smooth circulation flow inside.

<Embodiment> An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a configuration diagram of an embodiment of the present invention, in which an internal structure of a laser chamber 1 shown by cutting in a direction orthogonal to a laser light emitting direction and an excitation circuit diagram are shown together.

A laser chamber 1 filled with an excimer gas, which is a laser medium, has a flat plate-shaped flange portion 12 fixed to a main body 11 forming a part of a cylindrical shape.

The main electrode pair E _d for exciting the laser discharge is composed of a cathode E _dc connected to the capacitor C ₁ and an anode E _da electrically connected to the laser chamber 1 on the ground side. E _dc is close to the flange portion 12 of the laser chamber 1 and this flange portion is provided via an insulator 13.
It is fixed to 12, and the anode E _da is also to the flange part 12,
It is supported via columns 14 and a support plate 15 made of a conductive material.

The preionization electrode pair E _p is composed of a plate-shaped electrode E _pL and a pin-shaped electrode E _pi , and is arranged in proximity to the cathode E _dc side of the main electrode pair E _d . That is, on both sides of the cathode E _dc ,
Plate-shaped electrodes E _pL and E _pL formed so that their tips open toward the anode E _da side are fixed, and adjacent to the plate-shaped electrodes E _pL and E _pL , as shown in FIG. As shown in the perspective view of the main part, a plurality of pin-shaped electrodes E _pi ... E _pi are arranged with a predetermined distance from each other and the tips of the respective plate-shaped electrodes E _pL and E _pL reaching the vicinity of the tips. It is set up. The root of each pin-shaped electrode E _pi … E _pi is the peaking capacitor C ₂ respectively.
... C ₂ is directly connected mechanically and electrically, and each of the peaking capacitors C ₂ ... C ₂ is directly connected mechanically and electrically to the flange portion 12. An equivalent circuit of the embodiment of the present invention having the above structure is shown in FIG.

Inside the laser chamber 1, there are arranged a fan 2 for generating a gas flow across the main electrode pair E _d from the lower side to the upper side in FIG. 1, and heat exchangers 3, 3 for cooling the gas. It is set up. A guide plate 4 is provided between the fan 2 and the main electrode pair E _d.
Is provided.

According to the above embodiment of the present invention, the gas flow generated by the rotation of the fan 2 is guided by the guide plate 4 and the lower plate-shaped electrode E _pL to be guided between the main electrode pair E _d , and then the upper plate-shaped electrode E _d. The electrode E _pL guides the heat to the heat exchangers 3, 3 side, and reaches the fan 2 again, resulting in a smooth circulation flow without obstacles.

In the above examples, among the preionization electrode pairs E _p ,
Although the electrode connected to the cathode E _dc side has a plate shape to guide the gas flow, the electrode connected to the peaking capacitor C ₂ may have a plate shape. That is, as shown in FIG. 4 which is a main part configuration diagram, the cathode of the main electrode pair E _d .
A plate formed by connecting a plurality of pin-shaped electrodes E _pi ′ ... E _pi ′ to E _dc , and guiding the gas flowing along the guide plate 4 between the main electrode pair E _d to the peaking capacitor C _2. Electrode E
You may connect _pL '.

Further, the shape of the plate electrode E _pL or E _pL ′ is shown as a flat plate in FIG. 1 or 4, but it is needless to say that it may have a curved shape.

Furthermore, the structure of the present invention is not limited to the excimer laser, but is also a laterally pumped laser that requires a high-speed gas flow, for example,
It can also be applied to CO ₂ lasers and the like.

<Effect of the Invention> As described above, according to the present invention, the preionization electrode pair and the peaking capacitor are provided on the cathode side of the main electrode pair, which is disposed in the vicinity of the laser chamber wall, and the preionization electrode is provided. Since one of the pair is configured to guide the gas flow using a plate-shaped electrode, there is no obstacle in the gas flow path as in the past, a smooth circulating flow is formed, and a uniform and high-speed gas is formed in the main discharge area. The flow can be easily obtained. In particular,
In the downstream part of the gas, it was difficult to obtain a high-speed flow with the structure provided with the conventional pin electrode pair, and arc discharge was likely to occur, but by using one of the plate electrodes as in the present invention, this drawback is solved. , Stable high-repetition oscillation became possible without enlarging the fan and motor.

Further, by using one of the electrode pairs for preionization as a plate-shaped electrode, there is also an effect that the electrode interval can be easily adjusted and assembled as compared with the case where a conventional pin electrode pair is provided.

Furthermore, if the peaking capacitor is directly connected to the cathode side and to the laser chamber wall without arranging the peaking capacitor on the anode side as in the conventional case, in addition to the effect that a smooth gas flow is obtained as described above, the holding member is used. It is not necessary and the structure is simplified and the assembly is easy, and in addition to using one of the electrode pairs for preionization as a plate electrode, the number of parts to be inserted into the laser chamber is reduced and halogen gas There is also an effect that the possibility of the reaction is reduced and the gas life is extended.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an embodiment of the present invention, in which an internal structure of a laser chamber 1 shown by cutting in a direction orthogonal to a laser light emitting direction and an excitation circuit diagram are shown together, and FIG. 2 is a main electrode pair thereof. FIG. 3 is a perspective view of a main part showing the relationship between the cathode E _{dc of} E _d and the preionization electrode pair E _p , and FIG. 3 is an equivalent circuit diagram thereof. FIG. 4 is a schematic view of the essential parts of another embodiment of the present invention. FIG. 5 is an equivalent circuit diagram showing a general excitation circuit of a discharge excitation excimer laser, FIG. 6 is an equivalent circuit diagram showing a general excitation circuit of an automatic preionization type laser, and FIG. 7 is a conventional capacitor built-in type. It is a block diagram of a laser. 1 …… Laser chamber 11 …… Main body 12 …… Flange part 13 …… Insulator 14,14 …… Post 15 …… Support plate 2 …… Fan 3,3 …… Heat exchanger 4 …… Guide plate C ₂ … … Peaking capacitor E _d …… Main electrode pair E _dc …… Cathode E _da …… Anode E _p …… Pre-ionization electrode pair E _pL …… Plate electrode E _pi …… Hin electrode

Claims (1)

[Scope of utility model registration request] 1. A main electrode pair for laser discharge, a preionization electrode pair that discharges prior to the discharge of the main electrode pair, and a preionization electrode pair in a laser chamber filled with a medium gas. In a laser device having a peaking capacitor connected in series and a fan for giving a gas flow between the pair of main electrodes, the cathode side of the pair of main electrodes is arranged close to the wall of the laser chamber, and The electrode pair for ionization and the peaking capacitor are arranged close to the cathode side of the main electrode pair, and the peaking capacitor is supported on the wall of the laser chamber, and the electrode pair for preionization has one of the electrodes described above. With a plate-shaped electrode arranged in a direction that can guide the gas flow by the fan,
The other is composed of a plurality of pin-shaped electrodes,
Excimer laser device.