JP2003051634A - Discharge excited laser - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a discharge excited laser where variations in the irradiation position of a laser beam is small. SOLUTION: The discharge excited laser has a line select module that is arranged inside a laser resonator and includes an angle dispersion element, a monitor module that detects the deviation in the emission position and/or direction of a laser beam that is generated by the laser resonator, and a control means for controlling the attitude angle of the angle dispersion element, based on the detection result of the monitor module.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates generally to laser devices, and more particularly to F ₂ (molecular fluorine).
The present invention relates to a discharge excitation type laser device using ne) as a laser medium.

[0002]

2. Description of the Related Art As the degree of integration of semiconductor devices improves, exposure
An exciter that emits short-wavelength laser light as a light source for the device.
Maresa device and F₂Laser devices are receiving attention. F₂Les
Select one of the multiple oscillation lines of the laser
Line select F to oscillate ₂With lasers,
Normally, an angle dispersive element such as a prism or a total reflection mirror is used.
Line selection is being done. Also, KrF laser
Device, excimer laser device such as ArF laser device
Since the oscillation spectrum width is wide,
Toll narrowing is performed. Narrowing the band, for example
It is performed using a prism and a diffraction grating.

FIG. 18 shows the structure of an F ₂ laser device of the above-mentioned line select system. In the laser device shown in FIG. 18, windows 3 and 4 are provided on both sides of the laser chamber 1. In the laser chamber 1, two electrodes 2 for discharge, that is, an anode electrode and a cathode electrode, are arranged vertically (in front and at the back side in parallel with the paper surface). A high-voltage power supply (not shown) is placed between these electrodes.
A high voltage for discharge is applied by. The discharge direction is the vertical direction (V direction) orthogonal to the paper surface. In the laser chamber 1 filled with the laser gas that is the laser medium, a discharge is generated between the two electrodes 2, whereby the laser gas is excited and laser oscillation occurs. Note that FIG.
8, the laser resonator is composed of an output coupler 10 and a total reflection mirror 113 which will be described later.

A line select module 100 is arranged on the rear side of the laser chamber 1. The line select module 100 includes, for example, an angle dispersion element 115 including a prism 111 and a prism 112 and a total reflection mirror 113, which are installed in this order. The angle dispersion direction of the angle dispersion element 115 is the horizontal direction (H direction) orthogonal to the discharge direction. Further, on the front side of the laser chamber 1, a slit 5 and an output coupler 10 are provided.
And are arranged in this order.

As shown in FIG. 19, there are mainly two lines oscillated in the F ₂ laser device (wavelength λ ₁ = 157.6).
299 nm, wavelength λ ₂ = 157.5233 nm: Sov. J. Quantum Elect
ron.16 (5), May 1986), its spectral linewidth (FWH
M) is about 1 pm. The intensity ratio I (λ ₁ ) / I (λ ₂ ) of the two oscillation lines is about 7. Usually, an oscillation line with a strong wavelength λ ₁ is used for exposure.

Line selection of an oscillation line having a strong intensity wavelength λ ₁ (= 157.6299 nm) is performed as follows.
Due to the dispersion action of the angle dispersion element 115 including the prisms 111 and 112, the refraction angles of the two oscillation lines (wavelengths λ ₁ and λ ₂ ) in the angle dispersion element 115 are different. The beam emitted from the angle dispersion element 115 passes through the windows 3 and 4 and reaches the slit 5 having an opening. Here, the angle dispersion element 115 is arranged so that only the oscillation line (wavelength λ ₁ ) passes through the opening of the slit 5 and the other oscillation lines (other wavelengths including the wavelength λ ₂ ) are shielded by the slit 5. As a result, the oscillation line having the wavelength λ ₁ can be selected.

In FIG. 19, the area shown by the broken line is
The wavelength selection range 161 of the prism. The wavelength selection range of the prism is not blocked by the slit 5,
It corresponds to the wavelength range of the light emitted in the direction of passing through the opening of the slit 5. That is, the angle dispersion element 115 has an oscillation line of wavelength λ ₁ within the wavelength selection range 161 of the angle dispersion element 115 and an oscillation line of wavelength λ ₂ (= 157.5233 nm) outside the wavelength selection range. The line selection of the wavelength λ ₁ is performed by adjusting As a result, the oscillation line of wavelength λ ₂ is not emitted from the F ₂ laser device.

On the other hand, in an excimer laser device such as a KrF laser device or an ArF laser device, the band is narrowed as described above. FIG. 20 shows a configuration example of the narrow band excimer laser device. The configuration example of this narrow band excimer laser device is a line select type F ₂ shown in FIG.
In the configuration example of the laser device, a line narrowing module 120 is arranged instead of the line select module 100 arranged on the rear side of the laser chamber 1, and the other components are the same. The band narrowing module 120 includes, for example, one or two or more prisms (in the configuration example shown in FIG.
1, 122) and an Echelle type diffraction grating 123 arranged in a Littrow arrangement, which are arranged in this order.

In FIG. 21, the oscillation spectrum of the excimer laser device in which the band is not narrowed has a wavelength of λ ₀ (Kr
F laser device: about 248 nm, ArF laser device: about 1
(93.4 nm) as the center and spreads about 300 nm.
By narrowing the band, the width of the spectral waveform of the laser beam becomes narrow. The band narrowing is performed by selecting the wavelength of the diffraction grating arranged in the Littrow, and the selection of the wavelength is performed by adjusting the incident angle of the laser beam on the diffraction grating.

When laser light is output for a long time, the laser light is absorbed in the prism, the temperature of the prism rises, the refractive index of the prism increases, and the refraction angle of the beam changes. In the case of an excimer laser device, alignment of the laser beam with respect to the diffraction grating hardly changes, so the laser output does not decrease.

On the other hand, in the case of the F ₂ laser device, when the refraction angle of the prism changes, for example, the prism wavelength selection range 161 in FIG. 19 shifts in the arrow direction to become the prism wavelength selection range 162, and the intensity of the oscillation line of wavelength λ ₁ Is reduced. Further, the traveling direction of the laser beam itself is deviated, and the laser beam cannot be efficiently output to the exposure device, which is a problem. Further, when the traveling direction of the laser beam is deviated, the optical axis of the laser resonator formed by the total reflection mirror 113 and the output coupler 10 is deviated, so that the laser output is reduced unlike the case of the excimer laser device. .

For example, as shown in FIG. 22, the material is Ca
When the temperature of the prism F ₂ changes by 1 Kelvin (K), the passing position of the laser beam immediately after the prism exits changes by about 0.2 mm. In the case of the F ₂ laser device for exposure, the wavelength of the laser light is 157 nm, which is in the VUV (vacuum ultraviolet) region, and the material of the prism that transmits light in this wavelength region is actually only CaF ₂ . The F ₂ laser beam having a shorter wavelength than the KrF laser beam and the ArF laser beam has a large absorption for CaF ₂ , and the average output of the laser beam required for the exposure F ₂ laser device is as large as 40 W, so the temperature of the prism rises. Is likely to occur.

In a semiconductor exposure apparatus using a fluorine molecular laser device as a light source, specifications are provided so that fluctuations in the traveling direction of the laser beam fall within a predetermined range.
Specifically, specifications are provided so that the beam positioning stability and the beam pointing stability fall within a predetermined range. The beam positioning stability refers to the stability of the emission position of the laser beam. For example, specifications are provided so that the emission position 42 indicated by the broken line in FIG. 23 does not greatly deviate from the emission position 41 indicated by the solid line. There is. In addition, the beam pointing stability indicates stability in the emitting direction of the laser beam, and for example, specifications are provided so that the emitting direction 52 shown by the broken line in FIG. 24 does not largely deviate from the emitting direction 51 shown by the solid line. Has been.

[0014]

However, in the conventional F ₂ laser apparatus, the beam positioning stability and the beam pointing stability often do not satisfy the required specifications, and as described above, the light of the laser resonator is not used. A decrease in the laser output due to the misalignment of the axes has been a major problem. The present invention is
The present invention has been made to solve the above problems, and an object of the present invention is to provide a laser device in which variations in the emission position and emission direction of a beam are small.

[0015]

In order to solve the above problems, a discharge pump type laser device according to a first aspect of the present invention is provided with a line select module which is disposed inside a laser resonator and includes an angular dispersion element. A monitor module for detecting the deviation of the emission position and / or the emission direction of the laser light generated by the laser resonator, and an attitude angle control means for controlling the attitude angle of the angle dispersion element based on the detection result of the monitor module. To do.

A discharge excitation type laser device according to a second aspect of the present invention is a line select module arranged inside a laser resonator and including an angle dispersion element and a total reflection mirror, and a laser generated by the laser resonator. Light emission position and /
Or a monitor module that detects the deviation of the emission direction,
Attitude angle control means for controlling the attitude angle of the total reflection mirror based on the detection result of the monitor module.

A discharge excitation type laser device according to a third aspect of the present invention includes a line select module disposed inside a laser resonator and including an angle dispersion element, and temperature detection means for detecting the temperature of the angle dispersion element. And temperature control means for controlling the temperature of the angular dispersion element based on the detection result of the temperature detection means.

According to the present invention configured as described above, since the means for controlling the attitude angle or the temperature of the angle dispersive element is provided based on the detection result of the monitor module or the temperature detecting means, the irradiation position of the laser beam is provided. Can be suppressed to a small value.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. In addition, the same reference numerals are given to the same components, and the description thereof will be omitted. FIG. 1 shows the configuration of an F ₂ laser device according to the first embodiment of the present invention. FIG. 1 is a view of the laser device as seen from above.

As shown in FIG. 1, windows 3 and 4 are provided at both ends of the laser chamber 1. In the laser chamber 1, two electrodes 2 for discharge, that is, an anode electrode and a cathode electrode, are arranged vertically (in front and at the back side in parallel with the paper surface). A high voltage for discharge is applied between these electrodes by a high voltage power supply (not shown). The discharge direction is the vertical direction (V direction) orthogonal to the paper surface.

On the rear side of the laser chamber 1, there is arranged a line select module 100 in which an angle dispersion element 115 including a prism 111 and a prism 112 and a total reflection mirror 113 are installed in this order. The angle dispersion direction of the laser beam is the horizontal direction (H direction) orthogonal to the discharge direction. Further, on the front side of the laser chamber 1, a slit 5, an output coupler 10, and a monitor module 200 for detecting a deviation in the emitting position or emitting direction of the laser beam are arranged in this order. The line select function of the angle dispersive element 115 allows the wavelength λ ₂
The component is blocked by the slit 5. Here, the angle dispersion direction of the angle dispersion element 115 is preferably the horizontal direction (H direction). The shape of the laser beam on the plane perpendicular to the traveling direction is a rectangular shape having long sides in the discharge direction. Therefore, when the oscillation lines λ ₁ and λ ₂ are separated by the dispersion of the angle dispersion element 115, dispersion in the short side direction (H direction) of the rectangular shape is distributed in the long side direction (V direction) rather than dispersion in the long side direction (V direction). The number of prisms forming the angle dispersion element 115 can be small. For example, the angle dispersion element 1
When the number of prisms forming 15 is the same and the positions of the slits 5 are the same, oscillations of wavelengths λ ₁ and λ ₂ are generated when dispersed in the H direction as shown in FIG. The lines can be separated, but when dispersed in the V direction as shown in FIG. 2B, the oscillation lines having the wavelengths λ ₁ and λ ₂ cannot be separated.

In the present embodiment, the case where two prisms are arranged as the angle dispersion element is illustrated, but one or three or more prisms may be arranged. Also, FIG.
As shown in, the wavelength is about 157n as an angle dispersive element.
HR made of a dielectric material with high durability against m light
(High Reflection) The prism 114 having the coating layer 116 may be arranged. In this case, it is not necessary to arrange the total reflection mirror.

Referring again to FIG. 1, the monitor module 200 reflects a part of the light incident from the laser chamber 1 in the first direction (the lower side in the drawing) and outputs the remaining light as the output laser light. Is provided with a beam splitter 211 that transmits in the second direction (right side in the drawing) and a line sensor 212 that monitors the light reflected in the first direction.

Here, a laser medium of F ₂ gas and a buffer gas (either He or Ne or a mixed gas of He and Ne) is supplied into the laser chamber 1, and a high voltage is applied between the electrodes to cause discharge. Then, the light generated from the laser medium is refracted by the prisms 111 and 112 and totally reflected by the total reflection mirror 113, and then the prisms 112 and 111 are generated.
The wavelength is selected by refracting again. The selected wavelength component enters the laser chamber 1 from the window 3, the amplified laser light passes from the laser chamber 1 to the window 4 and then to the slit 5,
While resonating with the output coupler 10, a part thereof is output to the outside of the laser resonator.

The laser light emitted from the output coupler 10 is split into the first direction and the second direction by the beam splitter 211, and the laser light reflected in the first direction is installed below the beam splitter 211. The incident line sensor 212 is incident. The line sensor 212 is
For example, a CCD (charge coupled device) is used to measure the beam profile of incident light.

If the measured beam profile 214 of the laser beam deviates from the beam profile 213 indicating the irradiation position before the temperature of the angular dispersion element rises when the irradiation of the laser beam starts, the deviation amount 215 is Information such as size and direction is input to the controller 20.
The controller 20 rotates the rotary stage (not shown) on which the prisms 111 and 112 are mounted by a predetermined angle via the attitude angle control driver 30 of the angle dispersion element, so that the laser light emitted from the angle dispersion element is emitted. Feedback control is performed so that the position and the emission direction are constant.
That is, the laser characteristics such as the beam pointing characteristic and the beam position characteristic can be controlled based on the measurement result.

Since the beam changing direction due to the temperature rise of the angle dispersion element is mainly the angle dispersion direction (H direction in this embodiment), the line sensor is installed in the H direction and the horizontal position of the beam profile is set. The change was measured.

Here, the method of measuring the beam profile will be specifically described with reference to FIGS. 4 (a) and 4 (b). FIG. 4A shows a state in which the laser beam is received by the line sensor, and FIG. 4B shows a beam profile received by the line sensor. The beam shape 223 received by the line sensor 212 shifts in the horizontal direction (H direction) when the temperature of the angular dispersion element rises, and moves to the position of the beam shape 224. In this case, as shown in FIG. 4B, the center of gravity position 226 of the beam profile moves to the center of gravity position 227, so that the center of gravity position of the beam profile is monitored so that the variation of the center of gravity position is reduced. The attitude angle of the angle dispersive element may be controlled. Alternatively, as shown in FIG. 5, in the beam profile, the midpoint 236 of the full width at half maximum of the maximum intensity (I _max ) of the beam is monitored and the midpoint 237 of the shifted half width 237 is monitored.
The attitude angle control of the angle dispersive element may be performed so as to return to the original position.

Referring to (a) and (b) of FIG.
A specific example of the mechanism for adjusting the attitude angle of the angle dispersion element will be described. 6A is a front view of the prism 111 arranged in the line select module 100 shown in FIG. 1 as seen from the front direction (the lower side of FIG. 1), and FIG.
FIG. 3 is a right side view of the prism 111 as viewed from the right side (right side in FIG. 1). The prism 111 is arranged on the rotary stage 144, and the gear 146 rotates in response to the rotation of the pulse motor 145. The stage 144 is rotated. In this way, the controller can rotate the rotary stage by rotating the pulse motor and control the angle of the angular dispersion element installed on the rotary stage based on the result of monitoring the beam profile.

Although the example in which the prism 111 is driven is shown here, the prism 112 may be driven with the same configuration. Further, both the prism 111 and the prism 112 may be individually driven. Furthermore, the rotary stage 1
The prism 111 and the prism 112 may be arranged on the surface 44 to drive the prism 111 and the prism 112 at the same time.

Next, a second embodiment of the present invention will be described. The laser device according to the second embodiment of the present invention is
A line select module, a monitor module for detecting a deviation of the laser beam in the discharge direction, and means for controlling the attitude angle of the total reflection mirror are provided. In the present embodiment, the attitude angle of the angle dispersive element is fixed, and the attitude angle of the total reflection mirror installed in the line select module is controlled to reduce the variation in the emission direction of the laser light.

The laser light emitted from the output coupler is split into two directions by the beam splitter in the monitor module, and the beam profile is measured by the line sensor. The deviation of the beam profile is monitored, and the attitude angle of the total reflection mirror is controlled so as to reduce this deviation.

A specific example of a mechanism for adjusting the attitude angle of the total reflection mirror will be described with reference to FIG. In the line select module 150, a spring 156 that generates stress in a contracting direction is arranged at the lower left of the total reflection mirror 113, and the left end portion of the total reflection mirror is held in a state of being pulled downward. At the lower right of the total reflection mirror 113, a spherical movable holder 157 for keeping the distance between the right end of the total reflection mirror and the fixed plate 151 constant is arranged. The total reflection mirror has a contact point with the movable holder. It can be rotated from the base point. This mechanism is, for example, a structure similar to the gimbal mechanism. A pulse motor 145 is installed below the spring 156. Monitor module 200
The controller 20 rotates the pulse motor 145 via the driver based on the information on the horizontal deviation of the beam profile detected in step S1, and the spring 156 expands in accordance with the rotation of the pulse motor, so that the total reflection mirror 113 moves. The attitude angle is controlled. If two such pulse motors are used, not only the horizontal shift but also the vertical shift can be reduced.

Next, a third embodiment of the present invention will be described. FIG. 8 shows the configuration of a laser device according to the third embodiment of the present invention. In this embodiment, the irradiation position of the beam is controlled by adjusting both the attitude angle of the angle dispersion element and the attitude angle of the total reflection mirror. In FIG. 8, the prisms 111 and 112 in the line select module 160 arranged on the rear side of the laser chamber 1 are
It is installed on a rotary stage as shown in FIG. 6, and the total reflection mirror 113 is installed using a movable holder or the like as shown in FIG. A monitor module 260 is arranged on the front side of the laser chamber 1, and a beam fluorescent plate 261 for converting ultraviolet light into visible light and a profile measuring device 262 for measuring a beam profile are installed below the beam splitter 211. Has been done. Here, as the profile measuring device 262,
A CCD camera is used.

A part of the laser light split into two directions by the beam splitter 211 is incident on a beam fluorescent plate 261 installed below the beam splitter 211, and ultraviolet light is converted into visible light. Then, the CCD camera receives the light and measures the beam profile. Here, the deviation of the beam shape in both the horizontal direction and the vertical direction is detected. The deviation in both the horizontal and vertical directions may be adjusted by controlling the attitude angle of the total reflection mirror, or the deviation in the vertical direction may be adjusted by adjusting the attitude angle of the total reflection mirror so that the deviation in the horizontal direction is caused by the angle dispersion element. You may adjust by attitude angle control. The measured beam profile is transmitted to the controller 20. Based on this measurement result, the controller 20 transmits the prism 11 via the driver 30.
The feedback control of 1 and 112 is performed, and the attitude angle of the total reflection mirror is controlled via the driver 31.

In the laser devices according to the first to third embodiments of the present invention, an example of using a monitor module for measuring a beam profile has been shown. However, the amount of beam light is measured to shift the emission position of laser light. A monitor module that detects can also be used. In this monitor module, when the emitting position of the laser light is deviated, the light amount of the beam decreases, so that the emitting position of the laser light can be controlled by measuring the change in the light amount of the beam.

FIG. 9 shows an example in which the monitor module of the laser device according to the third embodiment of the present invention is changed to a monitor module for measuring the amount of light beam. In FIG. 9, the monitor module 270 is disposed on the front side of the laser chamber 1, and the monitor module 270
Inside, a second slit 271 below the beam splitter 211 and a beam diffusing plate 272 for irradiating uniform beam light in the vicinity of the second slit are arranged.
Below the beam diffusion plate 272, a pin (PIN) photodiode 273 is provided at a position close to the beam diffusion plate 272.
Are arranged. When the emission position of the beam shifts, a part of the beam is blocked by the second slit 271 and the light amount of the beam passing through the second slit 271 decreases. Therefore, the light amount of the beam incident on the beam diffusion plate 272 is also reduced, and the light amount of the beam that is uniformized by the beam diffusion plate 272 and received by the pin photodiode 273 is also reduced,
Beam output is reduced. Therefore, the controller 20
In order to increase the beam output, the attitude angle of the angular dispersion element 115 may be controlled via the driver 30, and the attitude angle of the total reflection mirror 113 may be controlled via the driver 31.

Further, in the laser devices according to the first to third embodiments of the present invention, the example of the monitor module for controlling the emitting position and the emitting direction of the beam is shown.
It is also possible to use a monitor module for controlling only the emitting direction of the beam. FIG. 10 shows an example in which the monitor module of the laser apparatus according to the third embodiment of the present invention is changed to one for controlling only the beam emission direction. In FIG. 10, the monitor module 280 is arranged on the front side of the laser chamber 1. In the monitor module 280, a beam splitter 211, a dimming plate 285 for dimming the beam intensity and a beam condensing lens 281 are arranged below the beam splitter 211, and further below the beam condensing lens 281, A two-dimensional sensor 284 is arranged at the focal length f of the beam condensing lens. The two-dimensional sensor is, for example, a two-dimensional line sensor and is composed of a CCD.

A part of the laser beam split by the beam splitter 211 in the monitor module 280 is focused on the two-dimensional sensor 284 by the beam focusing lens 281. Therefore, the deviation of the beam focused on the two-dimensional sensor 284 reflects only the deviation in the beam emission direction.
If the intensity of the beam focused on the two-dimensional sensor 284 is high and may damage the two-dimensional sensor, as shown in FIG.
And a beam condensing lens 281 are provided with a dimming plate 285 that reduces the beam intensity. Here, the dimming plate 285
May be disposed between the beam condensing lens 281 and the two-dimensional sensor 284.

The controller 20 controls the attitude angle of the angle dispersive element via the driver 30 and the driver 31 so that the deviation of the focal point on the two-dimensional sensor monitored by the two-dimensional sensor is reduced. By controlling the attitude angle of the total reflection mirror, the stability of the beam emission position (beam pointing stability) can be achieved.

Next, a fourth embodiment of the present invention will be described. The laser device according to the fourth embodiment of the present invention includes a temperature adjustment mechanism that detects the temperature of the angular dispersion element arranged in the line select module and adjusts the temperature of the angular dispersion element to be constant. In this embodiment, the temperature of the angular dispersion element increased by the laser light irradiation is adjusted to stabilize the irradiation position of the laser light.

FIG. 11 shows a first specific example of the temperature adjusting mechanism used in the laser apparatus according to the fourth embodiment of the present invention. Here, the temperature rise of the angle dispersion element 115 caused by the laser irradiation is reduced by providing the temperature adjustment mechanism 180. As shown in FIG. 11, the angle dispersive element 115 such as a prism arranged in the line select module is arranged on the rotary stage 184 in which the cooling water pipe 181 which is the passage of the cooling water is incorporated. The cooling water pipe 181 is connected to the cooling water supply device 182. When the temperature of the angular dispersion element rises due to the irradiation of the laser light, cooling water is supplied to remove the heat accumulated in the angular dispersion element. Here, it is preferable to keep the temperature of the angle dispersion element lower than room temperature, and it is desirable to keep it at 0 to 15 ° C. in consideration of practicality. Although only the temperature adjusting mechanism may be used to ensure the stability of the irradiation position of the laser light, as shown in FIG. 11, rotation is performed below the angle dispersion element 115 to adjust the attitude angle of the angle dispersion element. Stage 1
84 may be provided and the temperature adjustment mechanism and the attitude angle adjustment mechanism of the angle dispersion element may be used together.

12A and 12B show the shape of the cooling water pipe. FIG. 12 is a plan view of the rotary stage 184 seen from above. In FIG. 12A, in the rotary stage 184 provided below the angle dispersion element 115,
A U-shaped cooling water pipe 181a is arranged. Figure 1
2 (b), the cooling water pipe 181b meanders and has an M-shape. In FIG. 12B, since the cooling water pipe is long, it is advantageous to lower the temperature in a short time.

11 and 12 show the angle dispersion element 11.
Although one prism is shown as 5, it is also applicable to the case where two or more prisms are arranged as the angle dispersion element 115 as described above. At that time, one rotary stage 184 having the temperature adjusting mechanism 180
Alternatively, all two or more prisms may be arranged. Also,
The individual prisms may be arranged on the rotary stage 184 having the individual temperature adjustment mechanism 180. In that case, it is possible to individually control the temperature of each prism, or to control each prism by using both temperature adjustment and attitude angle adjustment together.

FIG. 13 shows a second specific example of the temperature adjusting mechanism for adjusting the temperature of the angular dispersion element. In this example, the angular dispersion element is controlled to be kept at a temperature higher than room temperature. In FIG. 13, the angle dispersive element 115 is surrounded by a heat insulating case 191.
It is arranged on a rotary stage 144 equipped with a pulse motor 145. A heater coil 192 is wound and arranged inside the heat insulating case 191.
A current can be passed through 92 to keep the inside of the case at a high temperature. According to this example, the temperature of the heat insulating case is higher than the temperature rise of the angle dispersion element due to the irradiation of the laser beam,
For example, since the temperature is set to be maintained at 50 ° C., the irradiation position of the beam can be stabilized. The temperature of the heat insulating case is preferably in the range of 40 to 50 ° C.
This is because if the temperature is 40 ° C. or higher, the temperature rise of the angle dispersion element due to the irradiation of the laser beam can be exceeded, while excessively high temperature is not desirable for the performance of the optical device.

FIG. 14 shows a third specific example of the temperature adjusting mechanism for adjusting the temperature of the angular dispersion element. In this example, the angular dispersive element can be held either below or above room temperature. In FIG. 14, Peltier elements (thermoelectric elements) 193 and 194 are provided above and below the angular dispersion element 115 so that a temperature gradient is not generated in the angular dispersion element.
Are arranged in pairs. The angle dispersion element 115 is provided with temperature sensors 195 and 196 such as thermocouples, and the outputs of these temperature sensors are supplied to temperature control units 197 and 198, respectively. The temperature control units 197 and 198 use the Peltier device 19 based on the outputs of these temperature sensors.
The currents supplied to 3 and 194 are controlled respectively. This is because the refractive index distribution is distorted when a temperature gradient occurs, which is to be avoided. In this example, the temperature of the angular dispersion element 115 can be set to an arbitrary temperature. Temperature controller 1
When the temperature of the angular dispersion element 115 rises or falls, 97 and 198 control the current of the Peltier element so that the temperature of the angular dispersion element 115 becomes equal to the set temperature.

Next, a control method in the laser device of the present invention will be described. FIG. 15 shows an example of a beam emission position and emission angle control method for measuring the spectrum intensity of the selected wavelength and controlling the beam emission position and the emission angle based on the measurement result in the embodiment shown in FIG. It is a flowchart. Here, the angle dispersion element 11
An example of controlling the attitude angle in the dispersion direction of either the prism 111 or the prism 112 out of 5 will be described. First, laser oscillation is performed in step S1, and it is checked in step S2 whether or not the number of shots has reached a prescribed number of shots. When the number of shots reaches the specified number of shots, the power lock is released (step S
3) At that time, the intensity I _{1 of} the light incident on the PIN photodiode 273 is measured (step S4). In step S5, the number of times of measurement is checked, and the process proceeds to each step according to the number of times of measurement.

In the first measurement, step S6
Then, the attitude angle in the dispersion direction of either the prism 111 or the prism 112 is rotated in the positive direction by the angle Δθ. In the second and subsequent measurements, the process proceeds to step S7 and the intensity I ₁ obtained by the current measurement
(N + 1) is the intensity I ₁ (n) obtained by the previous measurement
To determine whether or not increased. If the intensity is decreased, the posture angle in the dispersion direction of either the prism 111 or the prism 112 is set to Δθ in step S8.
Only in reverse rotation (rotation in the opposite direction to the previous time), and then the process returns to step S4 to perform the next measurement. On the other hand, when the intensity is increased, the posture angle in the dispersion direction of either the prism 111 or the prism 112 is rotated forward by Δθ (rotated in the same direction as the previous time) in step S9, and the intensity is measured in step S10. To do. It should be noted that if the intensities of this time and the previous time are the same, any posture angle may be selected.

In step S11 following step S10, the intensity I ₁ (n + 1) obtained by the current measurement is obtained.
Is smaller than the intensity I ₁ (n) obtained by the previous measurement. If the intensity has decreased, in step S12, the posture angle of either prism 111 or prism 112 in the dispersion direction is reversely rotated by Δθ, and the process ends, and if the intensity has increased, the process returns to step S9. , Prism 111 or prism 1
The forward rotation of any one of the posture angles 12 in the dispersion direction is repeated. By such processing, the beam emission angle can be controlled so that the intensity I ₁ is increased. Since the control method of this aspect is applied even when the wavelength monitor and the beam profile are not provided, the cost can be reduced.

FIG. 16 is a flow chart showing an example of a beam emission position and emission angle control method for measuring the beam profile of the selected wavelength and controlling the emission position and the emission angle of the beam based on the measurement result. First, in step S21, laser oscillation is started and then step S
At 22, the initial beam position of wavelength λ ₁ is measured by the profile measuring instrument, and at step S23 the initial beam position (X ₀ , Y ₀ ) is calculated. Here, the X direction corresponds to the H direction which is the dispersion direction of the angular dispersion element, and the Y direction corresponds to the V direction which is the discharge direction. Next, while performing laser oscillation in steps S24 and S25, the process moves to the next step when the prescribed number of shots is satisfied.

That is, in step S26,
Set the value of the number n to "1" and set the value in step S27.
Measure the arm profile. Based on this, steps
Beam position (X_n, Y_n) Is calculated and
Calculate the beam displacement (ΔX, ΔY) in step S29
To do. Further, in step S30, the beam displacement amount
(ΔX, ΔY) is a predetermined value (X_TH, Y_TH) Became
Or not. X _TH, Y_THThe value of is, for example, 0.5
mm. Beam displacement is below a certain value
In this case, return to step S24 and continue laser oscillation.
To do. On the other hand, if the beam displacement is below the specified value,
If not, the shape of the angle dispersive element is determined in step S31.
Δθ_X, And the attitude angle of the total reflection mirror in the V direction by Δ
θ_YOnly the number of measurements n in step S32.
Increments the value of and returns to step S27
Repeated measurement of beam profile and calculation of beam displacement
You By such processing, the intensity I₁So that
The beam emission angle can be controlled. The posture
Angle correction angle Δθ_XAnd Δθ_YIs Δθ_X= K_X・
ΔX, Δθ_Y= K_Y-Calculated as ΔY. Where K
_X, K_YIs a pulse per unit displacement in the X direction.
Motor rotation angle, pulse per unit displacement in Y direction
It is the rotation angle of the motor.

FIG. 16 shows a procedure of controlling using the beam profile measured by the profile measuring instrument in the laser device of the second embodiment of the present invention, but the control in the Y direction is omitted. Then, as it is, the procedure is to correct and control the deviation in the H direction (X direction) using the line sensor in the laser device of the first embodiment of the present invention. In addition, the control procedure shown in FIG. 14 is also applicable to the control of the beam emission direction (control of the beam pointing stability) in which the beam sampled by the beam splitter is condensed on the two-dimensional sensor and the deviation of the condensing point is corrected. , Can be applied as is. That is, the initial beam position (X ₀ , Y ₀ ) may be obtained as the position of the condensing point on the two-dimensional sensor.

F of the first embodiment of the present invention (see FIG. 1)
FIG. 17 shows the shift in the H direction between the excitation intensity and the beam profile when the laser output is controlled to be constant in the _two- laser device. The laser power depends on the high voltage applied between the electrodes in the laser chamber, the higher the voltage, the higher the laser power. That is, the high voltage corresponds to the excitation intensity when exciting the laser gas.

In the first embodiment of the present invention, as the number of laser pulses increases, the temperature of the prism forming the angular dispersion element 115 rises, and the beam emission position and / or
Alternatively, the emission direction is shifted and the beam displacement amount is increased. F ₂
In the laser device, if the emitting position or the emitting direction of the beam is deviated, the optical axis of the laser resonator is displaced, so that the laser output is reduced. In order to compensate for the output reduction due to the deviation of the optical axis, the controller controls the high voltage power supply (not shown) so that the voltage applied between the electrodes increases.

In FIG. 17, the number of laser pulses is A,
At B, C, D, and E, the deviation amount of the beam profile in the H direction becomes equal to or more than a predetermined value, so the controller 2
By 0, the attitude angle of the angle dispersion element 115 is corrected via the driver 30. Further, since the optical axis is aligned when the posture angle is corrected, the high voltage power supply is controlled by the controller so that the voltage applied between the electrodes is reduced. That is, the number of laser pulses A, B, C,
By correcting the attitude angle of the angle dispersion element 115 at the time of D and E, it was possible to maintain the deviation amount of the beam emission position and the emission direction within the predetermined range.

[0056]

As described above, according to the present invention,
Since the means for controlling the attitude angle of the angle dispersion element and / or the attitude angle of the total reflection mirror is provided, the stability of the irradiation position of the laser light can be achieved. Alternatively, according to the present invention, it is possible to reduce the effect that the temperature of the angle dispersion element rises due to the irradiation of the laser light, so that the irradiation position of the laser light can be stabilized. Therefore, it is possible to provide a laser device in which the variation of the beam irradiation position is small.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a laser device according to a first embodiment of the present invention.

2A and 2B are diagrams showing a beam shape on a plane perpendicular to a traveling direction of a laser beam, where FIG. 2A shows a case of dispersion in the H direction, and FIG. 2B shows a case of dispersion in the V direction. .

FIG. 3 is a diagram showing a specific example of an angle dispersion element used in the present invention.

FIG. 4 is a diagram showing a specific example of a method of measuring a beam profile in the monitor module of FIG.

5 is a diagram showing another specific example of the beam profile measuring method in the monitor module of FIG.

FIG. 6 is a diagram showing a specific example of a mechanism for adjusting the attitude angle of the angle dispersive element used in the first embodiment of the present invention.

FIG. 7 is a diagram showing a specific example of a mechanism for adjusting the attitude angle of the total reflection mirror used in the second embodiment of the present invention.

FIG. 8 is a diagram showing a configuration of a laser device according to a third embodiment of the present invention.

FIG. 9 is a diagram showing an example in which another monitor module is used in the laser device according to the third embodiment of the present invention.

FIG. 10 is a diagram showing another specific example of the monitor module used in the laser apparatus of the present invention.

FIG. 11 is a diagram showing a first specific example of the temperature adjustment mechanism used in the fourth embodiment of the present invention.

12 is a view showing the shape of the cooling water pipe of FIG.

FIG. 13 is a diagram showing a second specific example of the temperature adjusting mechanism of the angular dispersion element used in the fourth embodiment of the invention.

FIG. 14 is a diagram showing a third specific example of the temperature adjusting mechanism for the angular dispersion element used in the fourth embodiment of the invention.

FIG. 15 is a flowchart showing an example of a beam extraction angle control method used in the present invention.

FIG. 16 is a flowchart showing another example of the beam extraction angle control method used in the present invention.

FIG. 17 is a diagram showing a relationship between a laser pulse and a deviation of a beam profile in the H direction or an excitation intensity when the laser output is controlled to be constant in the first embodiment of the present invention.

FIG. 18 is a diagram showing a configuration of an F ₂ laser device by a line select system.

FIG. 19 is a diagram for explaining a wavelength selection range of a prism.

FIG. 20 is a diagram showing a configuration of a narrow band excimer laser device.

FIG. 21 is a diagram showing a spectral waveform of a laser beam that has not been band-narrowed and a spectral waveform of a laser beam that has been band-narrowed.

FIG. 22 is a diagram showing the relationship between the temperature change of the angle dispersion element and the deviation of the beam irradiation position.

FIG. 23 is a diagram for explaining beam positioning stability.

FIG. 24 is a diagram for explaining beam pointing stability.

[Explanation of symbols]

1 laser chamber 2 discharge electrodes 3, 4 wind 5 slits 10 Output coupler 20 controller 30 drivers 31 driver 41, 41 exit position 51, 52 Output direction 100, 150, 160 line select module 111, 112, 114 prisms 113 total reflection mirror 115 Angle dispersive element 116 HR coat layer 120 Band narrowing module 121, 122 Right angle prism 123 Echelle type diffraction grating 144,184 rotary stage 145 pulse motor 146 and 147 gears 151 Fixed plate 156 spring 157 Movable holder 180 Temperature control mechanism 181 Cooling water piping 182 Cooling water supply device 191 insulation case 192 heater coil 193, 194 Peltier device 195,196 Temperature sensor 197, 198 Temperature controller 200, 260, 270 monitor module 211 Beam splitter 212 line sensor 213, 214 beam profile 215 deviation 223,224 beam shape 261 beam fluorescent plate 262 profile measuring instrument 271, 281 beam condensing lens 272 Beam diffuser 273 pin photodiode 280 monitor module 284 two-dimensional sensor 285 Dim plate

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Nobuo Nansai, inventor             1200 Gigaphoton Co., Ltd. Manda 1200, Hiratsuka City, Kanagawa Prefecture             Inside the company (72) Inventor Osamu Wakabayashi             1200 Gigaphoton Co., Ltd. Manda 1200, Hiratsuka City, Kanagawa Prefecture             Inside the company F-term (reference) 5F071 AA06 EE02 HH02 HH05 JJ05                 5F072 AA06 HH02 HH05 JJ05 KK06                       KK15 KK26 KK30 RR05 TT01                       TT12 TT27 YY09

Claims (18)

[Claims] 1. A discharge pump type laser device, comprising: a line select module disposed inside a laser resonator and including an angle dispersion element; and an emission position and / or an emission position of laser light generated by the laser resonator.
Alternatively, a discharge excitation type laser device comprising: a monitor module that detects a deviation of an emission direction; and an attitude angle control unit that controls an attitude angle of the angle dispersion element based on a detection result of the monitor module. 2. The discharge excitation type according to claim 1, wherein the monitor module detects an emission position and / or a deviation of the emission direction of the laser light in the dispersion direction of the angle dispersion element. Laser device. 3. The discharge excitation type laser device according to claim 1, wherein the attitude angle control means controls the attitude angle of the angular dispersion element in a direction orthogonal to the discharge direction of the laser resonator. 4. A discharge pump laser device, comprising: a line select module disposed inside a laser resonator, the line select module including an angle dispersion element and a total reflection mirror; and an emission position of laser light generated by the laser resonator. as well as/
Alternatively, a discharge excitation type laser device comprising: a monitor module that detects a deviation of an emission direction; and an attitude angle control unit that controls an attitude angle of the total reflection mirror based on a detection result of the monitor module. 5. The discharge excitation laser device according to claim 4, wherein the attitude angle control means controls the attitude angle of the total reflection mirror in a direction orthogonal to the discharge direction of the laser resonator. 6. A discharge-excitation laser device, comprising: a line select module disposed inside a laser resonator, the line select module including an angle dispersion element and a total reflection mirror; and an emission position of a laser beam generated by the laser resonator. as well as/
Alternatively, a monitor module that detects a deviation of the emission direction, and based on the detection result of the monitor module, controls the attitude angle of the angle dispersion element in a direction orthogonal to the discharge direction of the laser resonator, A discharge excitation type laser device comprising: an attitude angle control means for controlling the attitude angle of the total reflection mirror in a direction parallel to the discharge direction. 7. The monitor module reflects a part of laser light generated by the laser oscillator in a first direction and uses the rest as output laser light.
1. A beam splitter that transmits in the direction of, and a sensor that detects the intensity of the laser light reflected in the first direction by the beam splitter.
6. The discharge excitation type laser device according to any one of 6 above. 8. The monitor module reflects a part of the laser light generated by the laser oscillator in a first direction and uses the rest as laser light for output.
7. A beam splitter that transmits in the direction of 1), and a one-dimensional sensor that measures the profile of the laser light reflected in the first direction by the beam splitter in a direction orthogonal to the discharge direction. 2. The discharge excitation type laser device according to item 1. 9. The monitor module reflects a part of the laser light generated by the laser oscillator in a first direction and uses the rest as laser light for output.
And a two-dimensional sensor for measuring the profile of the laser beam reflected in the first direction by the beam splitter in a direction orthogonal to the discharge direction and a direction parallel to the discharge direction. The discharge excitation type laser device according to claim 1. 10. The monitor module reflects a part of the laser light generated by the laser oscillator in a first direction and uses the rest as output laser light.
A beam splitter that transmits the laser beam reflected in the first direction by the beam splitter, a focusing optical system that focuses the laser beam reflected in the first direction by the beam splitter, and the position of the focusing point The two-dimensional sensor for measuring in a direction orthogonal to the discharge direction and in a direction parallel to the discharge direction. 11. A discharge pump type laser device, comprising: a line select module disposed inside a laser resonator and including an angle dispersion element; and temperature adjusting means for adjusting the temperature of the angle dispersion element to be constant. A discharge excitation type laser device comprising: 12. The temperature adjusting means includes a cooling water pipe arranged in proximity to the angle dispersion element.
The discharge excitation type laser device described. 13. The discharge excitation type laser device according to claim 11, wherein the temperature adjusting means includes a heater arranged near the angle dispersion element. 14. A line select module disposed inside a laser resonator and including an angle dispersive element, a temperature detecting means for detecting a temperature of the angle dispersive element, and the angle based on a detection result of the temperature detecting means. A discharge excitation type laser device comprising: a temperature control means for controlling the temperature of the dispersion element. 15. The temperature control means includes a pair of thermoelectric elements arranged in the vicinity of the angular dispersion element.
4. The discharge excitation laser device according to item 4. 16. The discharge pump type laser device according to claim 1, wherein the angular dispersion element includes at least one prism. 17. The angle dispersive element includes a prism having an HR (highly reflective) coating layer formed thereon.
17. The discharge excitation type laser device according to any one of items 1 to 16. 18. The discharge excitation type laser device according to claim 1, wherein the laser resonator contains F ₂ (fluorine molecule) as a laser medium.