JPS62111490A - Excimer laser apparatus - Google Patents

Abstract

PURPOSE:To obtain stable glow discharge even by less preliminary discharge, by forming UV light which is generated by the preliminary discharge, into approximately parallel beams by parabola reflecting mirrors, passing the beams in a main discharge region, and yielding ionization so that the most of the UV light contribute to the ionization of the main discharge region. CONSTITUTION:Main discharge in an eximer laser apparatus is performed between main discharge electrodes 1 and 2 to form a glow region 3. Meanwhile, UV light 6 is yielded between preliminary discharge electrodes 4 and 5 by preliminary ionization. The UV light 6 is formed into parallel beams 11 by parabola reflecting mirrors 9, which are provided behind the light. The beams pass the glow region 3, which is the main discharge region. Then ionization is yielded in the glow region 3 and a large amount of electrons are generated. Thus the stable glow discharge can be obtained, and the laser output is increased. When the parabola reflecting mirror 9 is made to turn around a supporting post 10, the UV light beams 11 are adjusted so that they are located at desirable positions between the main electrodes 1 and 2. The main discharge is carried out along the entire length between the main discharge electrodes 1 and 2.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an excimer laser device using diluted casshalide discharge excitation.

Excimer laser is a laser device that emits ultraviolet light, and is expected to find applications in semiconductor processing, chemical industry, medical care, and energy fields.

The excimer laser has a short laser upper level lifetime of approximately 1 to 5 years, and the stable period of claw discharge is at most 10 to 10 years due to the depletion of halogen molecules that contribute to stabilization through the formation of negative ions.
00. Since the discharge voltage is short, a short pulse discharge excitation with a rise time of about 1 O-rLs and a pulse width of 10YLS is required. However, in such a short time, the elementary phenomena required for normal claw discharge formation, such as the generation of secondary space, child generation, avalanche lightning, and separation, cannot occur, so in order to cause claw discharge to occur, This requires preliminary ionization using ultraviolet light (UV light), corona, X-rays, etc.

The conventional UV photon ionization method uses LIV on one side of the main discharge
A photon ionization electrode is arranged, and a preliminary ionization discharge is performed a certain period of time before the main discharge. This method is called a double discharge method because it causes two discharges. Also for pre-ionization electrodes,
There are two types: a series type in which creeping discharge occurs in series along a cut electrode, and a parallel type in which multi-bins are arranged in parallel.

Problems to be Solved by the Invention In the pre-ionization method, if the amount of pre-ionization is small, the main discharge tends to become an uneven arc, but if it exceeds a certain threshold, a stable or low discharge can be obtained; is estimated to be about 10 electrons/cc. However, with conventional methods, a sufficient amount of pre-ionization cannot be obtained.

In addition, as mentioned above, the main discharge occurs within an extremely short period of several tens of seconds (!), so it is unlikely that electron drift will occur during the discharge.Therefore, the generation of ionized electrons due to pre-ionization is unlikely. It is necessary for the main discharge to occur at the most desirable location.However, with conventional methods, this position can only be optimized by arranging the pre-ionization electrode, and sufficient position control cannot be achieved. .

The present invention has been made in view of the above points, and an object of the present invention is to increase the laser output by promoting the pre-ionization effect and generating a large amount of ionized electrons.

Means for Solving the Problems The present invention provides an excimer laser in which UV light generated by preliminary discharge is made into a nearly parallel beam using a parabolic reflector, and the beam is passed into the main discharge region to generate ionization there. It is a device.

Operation According to the above configuration, most of the UV light generated by the preliminary discharge contributes to ionization in the main discharge region, and a stable glow discharge can be obtained even with a small preliminary discharge, increasing the excimer laser output.

EXAMPLES Hereinafter, examples of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a perspective view showing an embodiment of an excimer laser device according to the present invention, and FIG. 2 is a sectional view taken along line A-A'i. In the figure, a main discharge takes place between main discharge electrodes 1 and 2, producing a glow region 3. On the other hand, pre-ionization is carried out by pre-discharge electrodes 4 and 5.
UV light 6 is generated. Preliminary discharge electrodes 4, 5
are provided in tens of pairs along the length of the laser tube, and generate UV light 6 at various locations along the length. 7 and 8 are electrodes 4
and a support that also serves as a lead to 5. The UV light 6 generated during pre-ionization 6 is converted into a parallel beam 11 by a parabolic reflector 9 installed behind it, and passes through a glow region 3 which is a main discharge region between main discharge electrodes 1 and 2. At this time,
Ionization can be generated in the glow region 3 to generate a large amount of ionized electrons.

As a result, stable glow discharge can be obtained and laser output can be increased. If the parabolic reflector 9 is rotatable around the support column 10, the UV light beam 11 can be adjusted to a desired position between the main electrodes 1 and 2. In practice, this amount of rotation may be adjusted experimentally so that the laser output is maximized. 12 is an output coupling mirror, 13 is a total reflection mirror, and 14 is an output beam.

In addition, other parts and devices such as a vacuum container, a blower device, and a cooling device are required in the actual LED, but these are known technologies in the field of excimer lasers and are not essential parts of the present invention. Therefore, illustration is omitted.

In the above configuration, the main discharge is performed over the entire length region between the main discharge electrodes 1 and 2. On the other hand, each pre-ionization electrode 4, 5
The UV light 6 generated in between is turned into a parallel beam 11 by a parabolic reflector 9 and passes through a discharge region spanning the entire length between the main discharge electrodes 1.2. This passing position can be adjusted by rotating the parabolic reflector 9 around the support column 1° so that the parabolic reflector 9 passes through an appropriate position where the maximum output can be obtained.

FIG. 3 shows an embodiment in which the pre-ionization discharge electrode 4°5 and the parabolic reflector 9 shown in FIG. growing. The configuration and operation of each part are essentially the same as those in FIGS. 1 and 2, so the same reference numerals are given and explanations will be omitted.

Effects of the Invention As described above, the present invention is configured to pass UV light from a pre-discharge as a parallel beam using a parabolic reflector at an appropriate position between the main discharge electrodes of an excimer laser device, thereby reducing the pre-ionization effect. By promoting stable low discharge, it is possible to increase the laser output and reduce the pre-ionization discharge power.

[Brief explanation of drawings]

FIG. 1 is a perspective view of a main part of an embodiment of an excimer laser device according to the present invention, FIG. 2 is a sectional view taken along line 8-A in FIG.
FIG. 3 is a sectional side view of main parts showing another embodiment of the excimer laser device according to the present invention. 1.2... Main discharge electrode, 3... Main discharge glow area,
4.5... Discharge electrode for preliminary ionization, 6... UV light, 9
...parabolic reflector, 11...parallel beam. Name of agent: Patent attorney Toshio Nakao (1st person)
Fig. 14 hc'-m Fig. 2 Fig. 3

Claims (3)

[Claims] (1) Features include a main discharge electrode and a plurality of preliminary discharge electrodes arranged in the length direction thereof, and the ultraviolet light generated by the preliminary discharge is turned into a parallel beam by a parabolic reflector and passed between the main discharge electrodes. excimer laser device. (2) The excimer laser device according to claim 1, wherein the parabolic reflector is rotatable about an axis parallel to the length direction of the main discharge electrode. (3) The excimer laser device according to claim 1, wherein the preliminary discharge electrode and the parabolic reflector are arranged symmetrically on both sides of the main discharge electrode.