JPH02144978A - Excimer laser apparatus - Google Patents

Abstract

PURPOSE:To prevent the surface of a capacitor from being corroded by a method wherein the capacitor is housed airtightly inside a container constituted by using an insulating material which is corrosion-resistant to a laser medium. CONSTITUTION:A container 1 is formed so as to airtightly house capacitors 3 arranged in a row at the upper and lower sides of a conductor 9 and is composed of a corrosion-resistant insulating material such as a fluorine resin, a ceramic or the like which can be divided into two parts. In this container 1, O-rings 2a composed of a fluorine rubber are fitted into packaging grooves formed in separation faces; O-rings 2b of the fluorine rubber are fitted into circular packing grooves formed so as to surround electrode-extension rods 4 of the discrete capacitors; accordingly, the capacitors 3 can be housed airtightly into the container. Thereby, it is possible to prevent the surface of the capacitors from being corded by a halogen element; it is possible to reduce an impurity generated inside a laser chamber to a minimum ; a laser medium can be made long-lived.

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention uses a diatomic gas containing a halogen element as a laser medium, and a capacitor necessary for generating a discharge to excite the laser medium is provided in this invention. The present invention relates to an excimer laser device disposed in a laser chamber in which a laser medium is enclosed.

[Conventional technology]

In excimer lasers, strong and fast excitation is required because the laser medium has a small ability to store energy.

In the case of the discharge excitation type, the -like discharge duration is usually about 100 nanoseconds, and even if the discharge is performed for a longer time than this, it will not contribute to excitation. Therefore, a faster rise and a larger discharge current lead to more efficient excitation. Therefore, it is necessary to reduce the impedance and time constant of the main discharge circuit by shortening the path of the main discharge circuit so that the inductance of the main discharge circuit that performs this large current discharge is as small as possible. For this reason, a main discharge circuit is constructed by arranging a capacitor inside a laser chamber in which a laser medium is sealed.

FIG. 3 shows a principle conceptual diagram of a cross section of a laser chamber in a conventional discharge-excited excimer laser device. The example shown in the figure shows the case of a capacitance transfer type automatic pre-discharge excitation excimer laser device, in which a U-shaped main discharge circuit conductor (hereinafter simply referred to as a conductor) 8 is arranged in a cylindrical laser chamber 7. It was arranged between the inner side surface and both sides of this conductor 8. A main discharge circuit conductor (hereinafter simply referred to as a conductor) 9 having a rectangular cross section.

Main radiation tt poles 6 are fixedly provided opposite to the central side of the conductor 8, respectively, and capacitors 3 are interposed between the upper and lower surfaces of the conductor 9 and the inner surfaces of both sides of the conductor 8. On the other hand, the conductor 9 and P2 are placed in the green state by the insulating sheath 5c! A preliminary discharge gap 5d is formed between the separated bottle 5a and the needle-like electrode 5b implanted in the conductor 9.

Here, code 4 connects both poles of capacitor 3 to conductor 8.
This is an electrode extension rod for connecting 9 and 1. Pre-ionization pins 5a, 5a arranged insulated from the conductor 9 were formed outside the laser chamber 7. Capacitor CI and inductance L! It is connected to an oscillating circuit consisting of a switching element S that repeatedly turns on and off at high speed, and 10,000 terminals of this oscillating circuit are further connected to the positive electrode of a high voltage power supply.

The operation of the excimer laser device configured as described above is as follows. During the OFF period of the switching element S, which repeats on-off operations at high speed, the capacitor CI charged via the inductance L1 from the high-voltage power supply attempts to discharge via the inductance LL due to the ON operation of the switching element S, and the capacitor CI is discharged from both ends of Ll. High voltage is applied to the terminal.

This voltage is applied to the pre-discharge gap 5d via the capacitor 3 which is in an uncharged state with Ls and CI in parallel, causing discharge to occur in this gap 5d, thereby charging the capacitor 3, and also charging the capacitor 3. The preliminary discharge stimulates the main discharge gap between the electrodes 6.6 to discharge the main discharge gap, through which the previously charged capacitor 3 is discharged. In this way, a large amount of charge transferred from the capacitor C1 in the external circuit to the capacitor 3 in the laser chamber is transferred to the capacitor 3. A discharge occurs all at once through the main discharge circuit consisting of the main discharge gap of the conductor 9 and the conductor 8. This causes a large current pulse glow discharge in the main discharge gap, and this discharge is repeated at high speed to excite the laser medium. do. Here, the capacitor 3 is usually a number n
It is formed by arranging a plurality of ceramic capacitors having a capacitance of F in a row in a direction perpendicular to the plane of the paper. Ceramic capacitors have many features such as excellent high-frequency characteristics against dielectric loss, almost no inductance, and can withstand high voltage, making them suitable as capacitors for excimer laser devices.

[Problem to be solved by the invention]

The problems with the excimer laser device configured in this way are as follows. That is, in conventional excimer laser devices, a capacitor whose surface is coated with a layer of resin such as epoxy resin by molding or the like is placed in the laser chamber as it is. Therefore, the problem is that the halogen element contained in the laser medium causes corrosion of the surface of the condenser, and the generation of impurities causes deterioration of the laser medium. In order to minimize the generation of impurities caused by halogen elements and prevent deterioration of the laser medium, the parts in the laser chamber that come into contact with gas other than the capacitor surface are coated with a Ni base material or Ni coating on the metal parts, and with a four-layer coating on the insulating parts. Countermeasures have been taken, such as using a base material made of fluororesin such as ethylene chloride resin, a fluororesin coating, or ceramics. However, none of the commercially available porcelain capacitors is molded or coated with a corrosion-resistant resin (eg, fluororesin).

As described above, in order to improve the performance of an excimer laser device, it is necessary to place a capacitor in the laser chamber, but this poses a problem of deterioration of the laser medium.

It is an object of the present invention to provide a construction for an excimer laser device that uses commercially available capacitors whose surfaces are not protected against halogen elements without causing surface corrosion within the laser chamber.

[Means for Solving the Problems] In order to solve the above problems, the present invention uses a gas of diatomic molecules containing a halogen element as a laser medium, and generates a discharge to excite the laser medium. In an excimer laser device in which a necessary capacitor is placed in a laser chamber in which the laser medium is sealed, the capacitor is hermetically housed in a container made of an insulating material that is corrosion resistant to the laser medium. shall be taken as a thing.

[Effect]

This invention provides a structure in which a corrosion-resistant insulating layer is further formed on a synthetic resin layer such as epoxy resin that has already been formed on the surface of the capacitor, as a means to protect commercially available capacitors from the corrosive effects of nitrogen elements. When trying to remove the molded product, a mold release agent is added to the surface of the synthetic resin layer to improve adhesion between the already formed synthetic resin layer and the new corrosion-resistant insulating layer. Silicone oil applied to the molding surface of the mold to remove the silicone oil, etc.) may cause problems in terms of cost and performance, such as the generation of microcracks during heating and cooling. As a means to prevent corrosion without forming,
In Figure 3, the capacitors are arranged in a row in a plane along the longitudinal direction of the main discharge circuit conductor in a laser chamber that is long in the direction perpendicular to the plane of the paper. is made separately from the capacitor,
The purpose is to prevent corrosion of the capacitor surfaces by airtightly housing the capacitors of each row in this container. According to this configuration, since the container is flat, it can be incorporated between conventional main discharge circuit conductors, and since the container has a simple shape, it does not require much cost to manufacture.

〔Example〕

FIGS. 1 and 2 illustrate an embodiment of the present invention.

In the figure, the same members as in FIG. 3 are designated by the same reference numerals, and their explanations will be omitted. In FIG. 1, reference numeral 1 indicates capacitors 3 arranged in a row perpendicularly to the plane of the paper on both the upper and lower sides of the conductor 9.
Formed so that it can be stored tightly.

It is a container made of corrosion-resistant insulating material such as fluororesin or ceramics that can be divided into two parts. 1 of each capacitor! By fitting a fluororubber O-ring 2b into a circular gasket groove formed surrounding the extension tube 4, the capacitor 3 can be airtightly housed in the container. In FIG. 2, reference numeral 1 (1 and 11 are female screws and holes for integrating the upper and lower parts of the two-split container, respectively, and reference numeral 12 is a hole for fixing the position of the capacitor 3 within the container 1). This is a hole for embedding a capacitor.

〔Effect of the invention〕

As described above, according to the present invention, a gas of diatomic molecules containing a halogen element is used as a laser medium, and a capacitor necessary to generate a discharge to excite the laser medium is enclosed in the laser medium. The excimer laser device disposed in the laser chamber is configured such that the capacitor is hermetically housed in a container made of an insulating material that is corrosion resistant to the laser medium, so that the halogen element on the surface of the capacitor is This makes it possible to prevent corrosion caused by metal parts without causing problems in terms of cost or performance.
Although we used i-coating and a corrosion-resistant resin base material such as fluororesin or ceramics or its coating for the insulating part, we were unable to suppress the corrosion caused by Noroken Motosuke on the capacitor surface as a laser medium. It is now possible to place the capacitor inside the laser chamber without touching it.

This makes it possible to minimize the generation of impurities inside the laser chamber, thereby extending the life of the laser medium. Because of the scales formed in the main discharge circuit, it is now possible to realize the conventional main discharge circuit, which has already been miniaturized, without making it thicker.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of an excimer laser device according to an embodiment of the present invention, FIG. 2 is an exploded perspective view of the vicinity of the capacitor in FIG. 1, and FIG. 3 is a cross-sectional view showing an example of the configuration of a conventional excimer laser device. It is a diagram.

Claims (1)

[Claims] 1) In an excimer laser device in which a gas of diatomic molecules containing a halogen element is used as a laser medium, and a capacitor necessary to generate a discharge to excite this laser medium is arranged in a laser chamber in which this laser medium is enclosed, An excimer laser device, wherein the capacitor is airtightly housed in a container made of an insulating material that is corrosion resistant to the laser medium.