JP2926191B2 - Laser device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a discharge excitation type laser device used as a light source for material processing, projection exposure, and the like.

[Conventional technology]

Discharge excitation type laser devices are used for material processing such as marking, cutting, welding, etc. In addition to large scale integrated circuits (LSI)
It is used as a light source for optical lithography for the production of the circuit pattern.

For material processing, CO ₂ , excimer laser, or the like is used. In optical lithography, a reduction projection method is mainly used. In this reduction projection method, transmitted light of an original image (reticle) pattern illuminated by an illumination light source is transmitted to a photosensitive material on a semiconductor substrate by a reduction projection optical system. Projection forms a circuit pattern. The resolution of this projected image is limited by the wavelength of the light source used. Therefore, in order to improve the resolution, the wavelength of the light source has been gradually shortened from the visible region to the ultraviolet region in recent years. Conventionally, g-line (wavelength 463 nm) and i-line (wavelength 3) generated from a high-pressure mercury lamp as a light source in the ultraviolet region.
65 nm) was used. But the line width of the smallest pattern is
When the size is less than 0.25 μm, which is required for 64 MB, the wavelength of the i-line has already reached the limit for shortening the wavelength. As a solution to this technical limitation, Deep Ultra Violet;
A laser light source (hereinafter referred to as Deep-UV) is promising.
In particular, excimer lasers have high output and high efficiency, and can obtain strong oscillation at short wavelengths such as KrF (wavelength 246 nm) and ArF (wavelength 193 nm) depending on the composition of the medium gas. Deep-UV above
In the region, the glass and crystal material constituting the reduction projection lens system are extremely restricted, so that it becomes difficult to correct the chromatic aberration used in the reduction projection lens system using a mercury lamp. Therefore, instead of correcting the chromatic aberration of the lens system, a wavelength selection element such as an etalon is provided in the laser resonator, and the spectral width of the output light is reduced to such an extent that the chromatic aberration of the lens material can be ignored. With this method, the output which was several nm in the spectrum width in the case of natural oscillation can be narrowed and narrowed to several pm.

[Problems to be Solved by the Invention] Such a narrow band excimer laser is a discharge excitation type laser device, and as shown in FIG.
A laser gas such as KrF is filled, and this laser gas is discharged and excited by electrodes 6 and 7 disposed vertically along the longitudinal direction of the laser chamber 1 to perform laser oscillation. In the drawing, a portion 11 surrounded by a broken line is a discharge excitation region.
The opposite surfaces 6a and 7a of the electrodes 6 and 7 are consumed by the discharge, and the discharge width is reduced.
WA changes. At the same time, the beam width of the output laser beam 4 changes. This poses a problem in terms of stabilizing the beam width. 2B is a cross-sectional view taken along line CC of FIG. 2A, and FIG. 2C is a vertical cross-sectional view of FIG. When used for processing, this change in the beam width of the laser degrades the transverse mode, changes the beam condensing property, and causes a change in output, which poses a practical problem.
In particular, when used as a light source for optical lithography, this change in beam width causes the following inconveniences in practical use of a narrow band excimer laser.

That is, it is well known that a wavelength selection element used for narrowing a band has an angular dispersion characteristic. For example, when a diffraction grating is used as a wavelength selection element, high-order diffraction is used to reduce the spectral width, so that the angular dispersion at the operating point is large and the divergence angle of the laser directly affects the spectral width. That is, when the divergence angle is large, the spectrum width is widened. Therefore, when the discharge width changes and the gain region changes, the beam divergence of the laser light changes, so that the spectrum width also changes greatly. In order to avoid this fluctuation, a conventional aperture 8 (FIG. 12 (a)) is provided to stabilize the gain width. However, the so-called conventionally used
In the case of a Chang-type electrode or the like, when the output is increased when the electrode is consumed, the discharge width inevitably increases greatly, so that the gain limitation by the aperture 8 makes it difficult to control the output.

Here, a mechanism for increasing the discharge width will be described.
Hereinafter, the electrodes will be represented by the CC section shown in FIG. 12 (b). Townsend theory is known as a macroscopic phenomenology for explaining the discharge phenomenon, and is useful for understanding the discharge phenomenon. According to this theory, a gas containing a halogen gas used in an excimer laser is called a negative gas, and captures electrons generated by impact ionization (ionization coefficient: α) of electrons during discharge due to a large electron affinity of halogen. (Electron attachment coefficient: η) and apparent ionization coefficient (α-η) are reduced to facilitate concentration of discharge. The relationship between these coefficients and the electric field strength E is shown in FIG. P is a constant for normalization.

As is clear from FIG. 13, the ionization coefficient α strongly depends on the electric field strength E, and the electron attachment coefficient η hardly depends on the electric field strength E. Therefore, the apparent ionization coefficient (α−η) has a certain electric field strength E As described above, the value rapidly increases and greatly depends on the electric field intensity E. That is, since the parameter (α-η) for driving the discharge changes according to the electric field intensity distribution on the electrode surface, the discharge width is greatly affected by the electric field intensity distribution on the electrode surface. For this reason, in order to secure a discharge width, it is necessary to make the electrode shape of the discharge excitation type laser device such that the electric field intensity region that is uniform in the electrode width direction can be large. Conventionally, based on the analytical solution of electric field calculation under ideal conditions, Chan
g, modified Chang type electrodes and other shapes have been adopted.

Here, FIG. 14 (a) shows the potential distribution of the electric field calculation in the case of the Chang type electrode. In FIG. 1A, L1... Are equipotential lines. From the figure, the cathode at the high negative potential (upper electrode)
It can be seen that the potential distribution between the anode 6 and the anode (lower electrode) 7 is greatly bent by the metal plate on which the anode 7 is mounted, the current return wiring 10 and the insulating member 9. That is, in the actual configuration, the electric field is shifted from the ideal Chang-type electric field due to such wiring and insulation.

FIG. 14 (b) shows the isoelectric field intensity line L2 near the cathode electrode 6.
.., (C) shows how the electric field intensity changes along the surface of the cathode electrode 6. The electric field intensity on the electrode has a small intersection with the equal electric field intensity line in a region separated by about 1/3 from the electrode center point (point A), and a uniform electric field is formed in this region. As can be seen from the line L3, the electric field intensity rises very slowly at first from the electrode center point A to the right end point (point B) of the electrode, and sharply increases as it approaches the end point B. FIG. 14 (d) shows isoelectric field intensity lines L4 near the anode electrode 7, and FIG. 14 (e) shows how the electric field intensity changes along the anode electrode surface. The electric field strength at the center point A is E ₀ . As shown in these figures, the electric field intensity is uniform in the first section of about 4 mm from the electrode center point (point A), and then gradually weakens toward the right end point of the electrode (point B), and after about 12 mm, sharply decreases. (See lines L4 and L5). This has a tendency opposite to that of the cathode 6 described above. Although the discharge occurs at the center of the electrode, it is considered that the factor limiting the width of the discharge is on the anode 7 side where the electric field intensity is large at the center.

The shape at the central portion of the consumed electrode was measured 1 × 10 ⁸ shots after the start of discharge, and the electric field intensity distribution at the central portion of the consumed electrode was calculated by a simulation analysis technique using the shape measurement data. The simulation results are shown in FIG. 15 where the horizontal axis represents the distance away from the center point A to the right and the vertical axis represents the rate of change ΔE / E of the electric field intensity E with respect to the electric field intensity E ₀ at the central point A. FIG.
Represents a cathode 6 and FIG. The white circles indicate before the start of discharge, and the black circles indicate after 1 × 10 ⁸ shots. As is clear from these figures, after 1 × 10 ⁸ shots, the wear has progressed, and the uniform electric field portion has spread in the central portion from the start. The width of this uniform electric field portion substantially corresponds to the observed beam width. This is considered to be due to the fact that the current was concentrated on the uniform electric field portion, which is a strong electric field, and the wear proceeded, and as a result, a wide uniform electric field portion was formed. As described above, in the conventional electrode configuration, when the operation of the laser device is started, the electrodes are worn out with the lapse of time, the uniform electric field portion is enlarged, and the beam width of the output laser light fluctuates accordingly. Become. This is because the electrode width is larger than the discharge width.

The present invention has been made in view of such circumstances,
It is an object of the present invention to provide a laser device capable of reducing a change in a beam width due to electrode consumption.

[Means for solving the problem]

Therefore, in the present invention, in a laser device that discharges between two electrodes disposed vertically facing each other along the longitudinal direction of the laser chamber and excites a laser gas in the laser chamber to generate laser light, The width of at least one of the two electrodes is made substantially equal to the discharge width, and conductors are arranged on both left and right sides of the at least one electrode along the longitudinal direction.

[Action]

That is, according to such a configuration, the discharge width becomes a constant width corresponding to the size of the electrode width. Therefore, the beam width of the output laser light becomes constant, and the laser device operates stably. In addition, the conductors disposed on both sides of the electrode reduce the consumption rate of the electrode and reduce contamination from the electrode.

〔Example〕

Hereinafter, embodiments of the laser device according to the present invention will be described with reference to the drawings. In the embodiment, a narrow-band oscillation excimer laser is assumed as the laser device. The apparatus of this embodiment has basically the same configuration as that shown in FIG. 12 and uses electrodes 12 and 13 described later instead of the electrodes 6 and 7. The laser chamber 1 is filled with a laser gas such as KrF, and the laser gas is discharged by an electrode 12 (cathode electrode) and an electrode 13 (anode electrode) arranged vertically along the longitudinal direction of the laser chamber 1. Excitation causes laser oscillation. The laser light is resonated by an optical resonator composed of a laser chamber 1, a front mirror 2, and a grating 5 as a wavelength selection element, and is output from the front mirror 2 as an effective laser light 4. The grating 5 narrows the oscillation light band and functions as a rear mirror, and has a so-called Littrow arrangement. In the drawing, a portion 11 surrounded by a broken line is a discharge excitation region, 8 is an aperture, 9 is an insulating member, and 10 is an anode current return wiring. WA indicates a discharge width. The electrode 13 is characterized in that a cross section perpendicular to the longitudinal direction of the laser chamber 1, that is, a line facing the electrode 12 among outer lines of a cross section is made elliptical. Further, a columnar metal structure 14 for electric field relaxation (hereinafter referred to as an electric field relaxation electrode) having a circular shape in the cross section is provided on both left and right sides of the electrode 13. In FIG. 12 (b), the right side is 14R and the left side is 14L in the arrow direction.
The cross sections of the electrodes 12, 13 are symmetrical left and right, and thus the potential distribution during operation of the laser device is symmetrical with respect to the center axis of the cross section. Therefore, the potential distribution is shown in FIG. 1 representatively of only the right portions of the electrodes 12 and 13.

In the figure, the upper side is a cathode electrode 12 having an arc-shaped facing surface 12a having a radius of 13 mm, and the lower side has a lateral electrode width of 8 mm.
Here, the opposing surface 13a is the anode electrode 13 formed in an elliptical shape. In this embodiment, the electrode 13 is formed such that the width of the electrode 13 matches the length of the major axis of the ellipse, and the center axis of the electrode 13 in the left and right direction matches the minor axis of the ellipse. The electrode interval between the cathode electrode 12 and the anode electrode 13 is 25 mm. That is, the width of the electrode 13 is equal to or less than the electrode interval. The cross section of the electric field relaxation electrode 14R on the right side of the anode electrode 13 is a circle having a diameter of 8 mm, and is electrically connected to the electrode 13. The same applies to the left electric field relaxation electrode 14L. That is, the electric field relaxation electrode 1
Reference numeral 4 denotes a step formed on the surface facing the electrode 13 so that the height is smaller than the height of the electrode 13. Here, since the electrodes 12 and 13 discharge, it is necessary to use a high melting point metal material or the like having excellent discharge resistance. On the other hand, the electric field relaxation electrode 14R (also 14L) does not discharge and only needs to hold the potential electrostatically. Therefore, it is not always necessary to use a high melting point metal material having excellent discharge resistance. It is possible to use a metal material different from the materials of the electrodes 12 and 13 having excellent characteristics.

FIG. 7A shows a simulation result when the minor / major axis ratio (r = minor axis / major axis) of the ellipse of the opposing surface 13a of the anode electrode 13 is r = 1, that is, when the opposing surface 13a is an arc. FIG. 6B shows the simulation results when the minor axis ratio r = 2, and FIG. 9C shows the simulation results when the minor axis ratio r = 4.
In the drawings up to FIG. 8, (a), (b) and (c) show the cases where the minor axis ratio r = 1, 2 and 4, respectively.

The tendency of the entire equipotential line is similar to that of the conventional one shown in FIG. 12 (a), but the equipotential line near the anode 13 is pushed up by the electric field relaxation electrode 14R and at the upper end portion (central axis portion) of the electrode. The potential gradient is gentle. This situation can be clearly seen in FIG.

FIG. 3 shows details of the electric field intensity distribution near the anode electrode 13, and FIG. 4 shows how the electric field intensity E changes on the surface of the electrode 13. In the case of the perfect circle of (a), the electric field intensity is strong at the center point A of the electrode 13, and becomes weaker and sharper toward the right end, and has a sharp distribution. (B) ellipse (ratio of minor axis to major axis)
In the case of (1: 2), the electric field distribution is flatter near the center point A than in the case of (a). Ellipse of (c) (minor-major axis ratio 1:
In the case of 4), on the contrary, the electric field intensity near the center point A becomes small and the electric field becomes strong at the central peripheral portion D.

Here, the effect of providing the electric field relaxation electrode 14 will be described. FIGS. 5 and 6 are diagrams showing details of the electric field intensity distribution near the anode electrode 13 when the electric field relaxation electrode 14 is not provided, and a diagram showing how the electric field intensity E changes on the surface of the electrode 13. . The comparison between FIGS. 5 and 6 and FIGS. 3 and 4 clearly shows that the provision of the electric field relaxation electrode 14 alleviates the electric field at the central peripheral portion D of the anode electrode 13, that is, the central point A and the peripheral portion D. It can be seen that the difference between the magnitudes of the electric fields at is small.

Further, the absolute value of the electric field intensity at the upper end of the anode electrode 13 is stronger in the order of (a), (b) and (c), and the electric field intensity becomes smaller at the center point A as the elliptical shape becomes flatter. It can be seen that the electric field in the peripheral portion D becomes stronger on the contrary.
The electric field strength at the center point A of the anode electrode 13 is as follows:
It can be seen that when the electric field relaxation electrode 14 is provided, the size is uniformly reduced as compared with the case where the electric field relaxation electrode 14 is not provided.

Now, it is assumed that the operator turns on the operation switch to start the operation of the laser device, and discharge starts from the state of (b). The electric field is fairly uniform over a wide range of the central portion of the facing surface 13a, and the discharge spreads over the entire elliptical portion 13a of the electrode 13, so that the consumption of the electrode 13 proceeds simultaneously over the entire elliptic portion 13a of the electrode 13. 4th
As can be seen from FIG. 7B, a larger amount of discharge current locally flows in a region near the center point A where the electric field is strong, so that this portion is consumed more quickly. Eventually, the state approaches (c), the electric field in the region near the center point becomes weak, and wear is reduced. This time, the electric field in the central peripheral portion D increases, and more discharge current flows in the peripheral portion D where the electric field is strong, so that the peripheral portion D is consumed more quickly. Thus, the state returns to the state of FIG. In this way, the shape of the discharge portion is settled in a certain stable shape between (b) and (c). Since the self-shape maintaining mechanism by such a kind of negative feedback mechanism works, a uniform electric field can be maintained in a certain region, and stable operation can be performed for a long period without changing the discharge width WA. The above was clarified from the simulation results.

Experimentally, when the minor axis ratio r is small, the electric field intensity E is strong at the center point A of the electrode, and rapidly decreases toward the peripheral portion D, so that the discharge is collected in a narrow central area. On the other hand, the minor axis ratio r
Is too large, the electric field strength E at the central peripheral portion D increases, and the discharge tends to concentrate on the peripheral portion of the electrode. In other words, there is a certain optimum value of the minor axis ratio r that does not concentrate at one location in the discharge. In the case of an experiment, when the minor axis ratio r = 3, the electric field is almost uniform over the electrode width and the length is almost the same as the electrode width. Discharge width WA was obtained. That is, the opposing surface 13a of the electrode 13 is formed with such an optimum ratio of the minor axis to the major axis, and when the laser operation is performed, the discharge spreads substantially over the entire surface of the electrode ellipse 13a, so that the wear proceeds simultaneously over the entire surface of the electrode ellipse 13a. Even if there is a locally strong electric field, more discharge current flows there, and it is consumed faster. Eventually, a kind of negative feedback mechanism that weakens the electric field in that part and reduces wear is activated. For this reason, a uniform electric field can be maintained for a long period in the region defined by the electrode width, and the operation can be performed with a constant discharge width.

Here, advantages of the provision of the electric field relaxation electrode 14 will be described. When the electric field relaxation electrode 14 is not provided, the electric field strength on the surface of the anode electrode 13 becomes large, and thus there is a disadvantage that there is much contamination from the electrode 13, but the electric field relaxation electrode 14 is provided. This has improved this point. Furthermore, when the electric field relaxation electrode 14 is not provided, the state of the distribution of the electric field intensity on the surface of the anode electrode 13 greatly changes depending on the shape of the anode electrode 13, and therefore, in particular, the discharge may become unstable at the start of the laser operation. However, this point was also improved by providing the electric field relaxation electrode 14. These experimental findings are almost in agreement with the simulation results, indicating that the findings are valid.

In this embodiment, a constant electric field is obtained on the entire surface of the electrode elliptic portion 13a at the minor axis ratio r = 3, and a discharge width WA equal to the electrode width is obtained. , The electrode spacing, the geometrical arrangement, the dielectric constant of the insulating part, and the properties of the discharge medium gas, it is necessary to find the optimum value according to the situation.

Although the cross section of the electric field relaxation electrode 14 is a circle in the embodiment,
The present invention is not limited to
As shown in the figure, the electric field relaxation electrode 15 having a cross section of 1/4 circle
It may be. 7 and 8 correspond to FIGS. 3 and 4, and it can be seen that equivalent effects are achieved.

The cross-sectional shape of the electric field relaxation electrode is not limited to that of the embodiment, and the electric field relaxation electrode 16 having a line formed by combining an ellipse and a straight line as the cross-sectional shape as shown in FIG. As shown in b), the electric field moderating electrode 17 may have a cross-sectional line formed by combining an arc and a straight line. Alternatively, it is conceivable that the cross-sectional shape is formed by an ellipse and a curve of a smooth functional system. In any case, if the straight lines and the straight lines or the curved lines and the straight lines are connected smoothly, electric field concentration is unlikely to occur, so that creeping discharge and unnecessary discharge can be prevented. In short, the electric field relaxation electrode may be any electrode provided on both sides of the adjacent discharge electrode.

When the electric field relaxation electrodes are provided on both sides of the discharge electrode in this way, when replacing the electrodes, only the cathode electrode and the anode electrode need to be exchanged, and the exchange of the electric field relaxation electrodes is unnecessary. Therefore, as compared with the case where each of the anode electrode and the cathode electrode is constituted by a single member, there is obtained an advantage that the cost at the time of replacement and further the reduction of the electrode manufacturing cost are obtained.

Further, in the embodiment, the discharge width WA having the same size as the electrode width is obtained for only one of the anode electrodes 13 and the electric field relaxation electrode 14 is provided, but as shown in FIG. ′, The discharge width is the same as the electrode width
It is also possible to form an opposing surface of each electrode so as to obtain WA, and to dispose electric field relaxation electrodes 14 ′ and 14 on each of the electrodes, and an effect equivalent to that of the embodiment can be obtained.

In addition, as a material of the electric field relaxation electrode, any metal, ceramic, or plastic can be used as long as it is a conductive substance. The electric field relaxation electrode only needs to be able to electrostatically hold the potential, and it is possible to cover the entire electric field relaxation electrode 14 with an insulating tube 18 as shown in FIG. 11 (a). As shown in FIG. 2B, it is also possible to cover a part with the insulator 19 and electrically (capacitively, inductively, resistively) connect the electrode 13.

In the embodiment, an electric field relaxation electrode is separately prepared in addition to the discharge electrode, and these are arranged adjacent to both sides of the discharge electrode. However, it is also possible to integrally form these.

〔The invention's effect〕

As described above, according to the present invention, it becomes possible to stably operate a discharge excitation type laser device without changing the discharge width for a long period of time. Therefore, if the present laser device is used for material processing, stable material processing without change in beam width and transverse mode can be performed for a long period of time, which is extremely useful in practical use. Also, by using a wavelength selection element inside or part of the cavity of this laser device, a narrow-band oscillation laser with extremely small fluctuation of the spectrum width can be realized. For a long period of time and is extremely useful in practice.

[Brief description of the drawings]

FIG. 1 is a diagram showing the distribution of equipotential lines near the electrodes used in the embodiment of the laser device according to the present invention, and FIG. 2 is a diagram showing the equipotential lines near the anode electrode shown in FIG. FIG. 3 is a view showing a distribution state, FIG. 3 is a view showing a distribution state of the electric field intensity in the vicinity of the anode electrode shown in FIG. 1, and FIG. 4 is a graph showing a change in the electric field intensity on the surface facing the anode electrode shown in FIG. FIG. 5 is a view showing the state, FIG. 5 is a view showing the distribution of the electric field intensity in the vicinity of the anode electrode when no electric field relaxation electrode is provided, and FIG. 6 is a view showing the electric field on the surface facing the anode electrode shown in FIG. FIG. 7 is a view showing a state of change in intensity, FIG. 7 is a view showing a state of distribution of electric field intensity near the anode electrode when the cross-sectional shape of the electric field relaxation electrode is different, and FIG. FIG. 9 is a view showing a state of a change in electric field intensity on the surface, and FIG. FIG. 10 is a view showing the shape of the electric field relaxation electrode in the embodiment, FIG. 10 is a view showing a cross section when the present invention is applied to both opposing electrodes, and FIG. 11 is an embodiment in which the electric field relaxation electrode is covered with an insulating film. FIG. 12 is a diagram showing an example, FIG. 12 is a diagram showing the entire configuration of a conventional laser device, FIG. 13 is a graph showing the field intensity dependence of the ionization coefficient, adhesion coefficient, and apparent ionization coefficient during excimer laser gas discharge, and FIG. Figure (a),
(B), (c), (d) and (e) show the potential distribution near both electrodes when using the electrodes according to the prior art, respectively.
FIG. 15 shows the electric field intensity distribution near the cathode electrode, the change in the electric field intensity on the surface facing the cathode electrode, the electric field intensity distribution near the anode electrode, and the change in the electric field intensity on the surface facing the anode electrode. 5 is a graph showing the rate of change of the electric field intensity on the electrode surface before and after laser operation when used. 1 ... laser chamber, 2 ... front mirror, 4 ...
Laser light, 5 ... Grating, 12 ... Cathode electrode, 13 ... Anode electrode, 14, 14 ', 15, 16, 17 ... Electric field relaxation electrode.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-62-169383 (JP, A) JP-A-63-21884 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) H01S 3/038 H01S 3/097-3/0977

Claims (10)

(57) [Claims] 1. A laser device which discharges between two electrodes disposed opposite to each other along a longitudinal direction of a laser chamber to excite a laser gas in the laser chamber to generate a laser beam. An opposing surface of the two electrodes is formed so that the width of at least one of the electrodes and the discharge width are substantially equal to each other, and both sides of the at least one electrode in the electrode width direction at the same potential as the electrode. In addition, a laser device is provided with an electric field relaxing conductor for reducing the difference between the magnitude of the electric field at the center of the electrode in the electrode width direction and the magnitude of the electric field at the peripheral portion in the electrode width direction. 2. An outer line facing the other electrode of the at least one electrode in an electrode width direction cross section is formed in an elliptical shape, and the width of the at least one electrode is the length of the major axis of the ellipse. 2. The laser device according to claim 1, wherein the center axis of the ellipse coincides with the minor axis of the ellipse. 3. The laser device according to claim 2, wherein the ratio of the major axis length to the minor axis length of the ellipse is in the range of 1 to 4. 4. The laser device according to claim 1, wherein the width of said at least one electrode is smaller than the distance between said two electrodes. 5. The laser device according to claim 1, wherein a material of said electric field relaxing conductor is different from a material of said at least one electrode. 6. The laser device according to claim 1, wherein said electric field relaxing conductor is housed in an insulating tube. 7. The laser device according to claim 1, wherein a part of the surface of the electric field relaxing conductor is coated with an insulating film. 8. The laser device according to claim 1, wherein an outer peripheral line of the electric field relaxing conductor in a cross section in the electrode width direction has a shape having a line formed by combining a circular line or an arc and a straight line. 9. The laser device according to claim 1, wherein said laser device is provided with an optical resonator having a wavelength selection element, and said optical resonator narrows an oscillation wavelength of said laser light. Laser device. 10. The laser device according to claim 1, wherein said electric field relaxing conductor is an electrode having a height lower than a height of said at least one electrode.