JPS62111489A - Excimer laser apparatus - Google Patents

Abstract

PURPOSE:To obtain stable glow discharge with less preliminary discharge, by converging UV light, which is generated by preliminary discharge, at a desired position in a main discharge region by pivotable mirror surfaces, and yielding ionization at the position so that most of the UV light contributes to the ionization in the main discharge region. CONSTITUTION:The main discharge of an excimer laser apparatus occurs between main discharge electrodes 1 and 2 and a glow region 3 is yielded. Meanwhile, preliminary ionization generates UV light 6 between preliminary electrodes 4 and 5. The UV light 6 is converged by a reflecting mirror 9 which is provided behind, and a focal point is formed at a point 11. The reflecting mirror is an elliptic mirror. The first focal point is set at a part, where the UV light 6 is generated, and the second focal point is set at the point 11. Then the UV light 6 is efficiently converged in the main discharge region even if the UV light has less discharge power. Thus sufficient amount of ionized electrons can be obtained. When the mirror can be turned around a supporting post 10, the focal point 11 can be adjusted so that the point 11 is located at the desired position between the main electrodes 1 and 2. The main discharge can be performed 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 that utilizes shalide discharge excitation.

Conventional technology Excimer lasers are laser devices that emit ultraviolet rays, and are expected to find application in semiconductor processing, chemical industry, medical care, energy fields, and other fields.

The excimer laser has a short laser upper level lifetime of approximately 1W, and the stable period of glow discharge is at most 100W due to the depletion of halogen molecules that contribute to stabilization through the formation of negative ions.
Since it is as short as 0ybs, short pulse discharge excitation with a rise time of approximately 10λS1 and a pulse width of 1013 is required. However, in such a short time, the elementary phenomena required for normal glow discharge formation, such as the generation of secondary electrons and avalanche ionization, cannot occur, so ultraviolet light is required to generate a claw discharge. Pre-ionization using (UV light), corona, X-rays, etc. is required.

In the conventional UV photon ionization method, a UV photon ionization electrode is placed on one side of the main discharge electrode, 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. There are also pre-ionization electrodes of the parallel type, in which multi-pins are arranged in series and in parallel to cause a creeping discharge to occur in series along an electrode with cuts.

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 glow discharge can be obtained; is estimated to be approximately 10 electrons/CC. However, with conventional methods, a sufficient amount of pre-ionization cannot be obtained.

Furthermore, as mentioned above, the main discharge is carried out within an extremely short period of several tens of vL5, so it is unlikely that electron drift will occur during the discharge. Therefore, it is necessary that the generation of ionized electrons by pre-ionization be performed at the most desirable location for the main discharge. However, in the conventional method, this position can only be optimized by arranging the pre-ionization electrode at most, 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 promote the pre-ionization effect, generate a large amount of ionized electrons, and increase laser output.

Means for Solving the Problems The present invention is an excimer laser device in which UV light generated by preliminary discharge is focused on a desired position within the main discharge area using a rotatable mirror surface, and ionization is generated there. be.

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 an A-A'! ! FIG. 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 occurs between the pre-discharge electrodes 4 and 5, generating UV light 6. preliminary discharge electrode 4,
Several tens of pairs of laser beams 5 are provided along the length of the laser tube, and JV light 6 is generated at various locations along the length. 7 and 8 are supports that also serve as leads to the electrodes 4 and 5. The UV light 6 generated by pre-ionization 6 is reflected by a reflecting mirror 9 installed behind it.
For example, the light is collected by an elliptical mirror and focused on a point 11.

If the reflector 9 is an elliptical mirror and the first focal point is set to the part that generates the UV light 6 and the second focal point is set to the point 11, even the UV light generated by a small discharge power will be efficiently focused on the main discharge area, and a sufficient amount will be generated. of ionized electrons are obtained. By allowing the reflecting mirror 9 to rotate around the support column 10, the focal point 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.

Note that actual lasers require other parts and devices such as a vacuum container, blower device, and cooling device, 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 I and 2. On the other hand, each pre-ionization electrode 4, 5
The UV light 6 generated during this period is directed to the main discharge electrode by a reflecting mirror 9]
, the light is focused over the entire length region between the two. This light condensing position can be adjusted by rotating the reflecting mirror 9 around the support column 10 so that the light is condensed at an appropriate position where maximum output can be obtained.

Figure 3 shows an embodiment in which the pre-ionization discharge electrodes 4.5 and the reflecting mirrors 9 shown in the figure are arranged symmetrically on both the left and right sides with the main discharge part in between, and the effect of pre-ionization is even greater. Become. 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 focuses UV light from a pre-discharge at a proper position between the main discharge electrodes of an excimer laser device using a reflecting mirror, thereby promoting the pre-ionization effect and producing a stable product. By causing glow 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 essential parts of an embodiment of an excimer laser device according to the present invention, FIG. 2 is a sectional view taken along line A-A' in FIG. 1, and FIG. 3 is another embodiment of an excimer laser device according to the present invention. FIG. 1.2... Main discharge electrode, 3... Main discharge glow region, 4
．． 5... Discharge electrode for preliminary ionization, 6... UV light, 9...
·Reflector. Name of agent: Patent attorney Toshio Nakao Haka 1st person
1 Fig./3 Fire attack 2 Lord Mufeng Reikin ・□ \l Calligraphy'-4 Fig. 2 3 + Yosho Hakuyo No. 3 Fig. s'5

Claims (4)

[Claims] (1) An excimer laser comprising a main discharge electrode and a plurality of preliminary discharge electrodes arranged in the length direction thereof, and which focuses ultraviolet light generated by the preliminary discharge between the main discharge electrodes using a reflecting mirror. Device. (2) The excimer laser device according to claim 1, wherein the reflecting mirror is an elliptical mirror, the preliminary discharge position is located at the first focal point, and the condensing position is located at the second focal point. (3) The excimer laser device according to claim 1, wherein the reflecting mirror is rotatable about an axis parallel to the length direction of the main discharge electrode. (4) The excimer laser device according to claim 1, wherein the preliminary discharge electrode and the reflecting mirror are arranged symmetrically on both sides of the main discharge electrode.