JP2005148549A - Optical pulse stretcher and exposure-excited gas laser apparatus for exposure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve alignment stability and beam quality stability and to prevent a decrease in laser output due to breakdown.
Incident light is split by a beam splitter 11, and enters the beam splitter 11 through a path of a total reflection mirror 12a, a lens 13, total reflection mirrors 12b and 12c, a lens 13, and a total reflection mirror 12d. Combined and emitted from the beam splitter 11. A slit 14 is provided on the exit side of the beam splitter 11, and when the total reflection mirrors 12 a to 12 d are tilted due to thermal deformation or the like and the beam profile is thick, only the thick portion is blocked by the slit 14. Thereby, the same profile as the incident beam can be obtained. Further, a position sensor for detecting the position of the incident laser beam may be provided, and the angle of the total reflection mirror may be adjusted based on the position information of the position sensor so that the position of the laser beam becomes a predetermined position. Good.
[Selection] Figure 3

Description

  The present invention relates to an optical pulse stretcher and a discharge-excited gas laser apparatus for exposure, and more particularly, a laser beam profile even when the temperature of the optical stretcher increases or when the temperature changes locally. The present invention relates to an optical pulse width expander capable of preventing the deterioration of the above and a narrow-band discharge excitation gas laser apparatus for exposure having the optical pulse width expander.

With the miniaturization and high integration of semiconductor integrated circuits, there is a demand for improvement in resolving power in an exposure apparatus for manufacturing the semiconductor integrated circuit. For this reason, the wavelength of the exposure light emitted from the exposure light source is being shortened. Conventionally, a KrF excimer laser device that emits ultraviolet light having a wavelength of 248 nm has been used as a light source for semiconductor exposure. At present, an ArF excimer laser device that emits ultraviolet light having a wavelength of 193 nm is reaching a practical stage as an exposure light source having a shorter wavelength. Furthermore, the adoption of a fluorine molecule (F2) laser device that emits ultraviolet light having a wavelength of 157 nm is considered promising as a light source for semiconductor exposure that will be the next generation.
Various types of excimer laser devices for exposure (hereinafter, these are referred to as discharge excitation gas laser devices) have been proposed so far, and laser devices equipped with a narrow band module for narrowing the spectrum width include, for example, It is disclosed in Patent Document 1, Patent Document 2, and the like.
In recent years, in the excimer lasers for exposure (KrF excimer laser, ArF excimer laser) and fluorine molecular lasers, in order to improve the throughput of the exposure apparatus and realize uniform ultrafine processing, the laser output is further increased and the laser beam power is increased. There is a demand for narrowing the spectral line width. For this reason, a two-stage laser apparatus using two lasers has been proposed (see, for example, Patent Document 3).

In narrow-band laser devices such as narrow-band oscillation excimer laser devices and fluorine molecular laser devices, the peak value of the laser oscillation pulse time waveform may be smaller than a predetermined value from the viewpoint of optical element degradation in the beam propagation system of the exposure device. It is requested. In order to reduce the peak value of the pulse time waveform, it is necessary to extend the time width of pulse light (hereinafter referred to as pulse width).
In order to extend the pulse width, as described in Patent Document 1, for example, the laser oscillation operation is performed by the first half cycle of the discharge oscillation current waveform of one pulse whose polarity is reversed, and at least one half cycle following it. It has been proposed to configure a power supply circuit of a laser device so as to perform the above.
In order to configure the power supply circuit as described above, it is necessary to determine circuit constants so that the peak value of the current becomes large, or to shorten the period after the first ½ period of the oscillating current flowing between the main discharge electrodes. For example, the power supply circuit is difficult to design and the configuration is complicated.
Therefore, an optical pulse that branches a part of the laser light emitted from the laser device with a beam splitter or the like, delays the branched light using a total reflection mirror, etc., and delays the time to combine it with the original laser light. A width expander has been proposed (see, for example, Patent Document 4 and Patent Document 5).
JP 2002-151768 A JP 2002-151776 A Japanese Patent Laid-Open No. 2003-198820 Japanese Patent Laid-Open No. 9-288251 US Pat. No. 6,535,531

However, the above-described conventional optical pulse width expander has the following problems.
(1) As described above, the optical pulse width expander [hereinafter also referred to as OPS (Optical Pulse Stretch Unit)] branches a part of the laser beam by a beam splitter or the like, and all the branched light is split. The pulse width is expanded by delaying the time by using a reflection mirror or the like and synthesizing with the original laser light again.
For this reason, if the temperature of the OPS main body rises or the temperature changes locally, the position of the relay lens included in the mirror or the delay optical system is shifted (alignment is shifted), and the laser beam profile is deteriorated. There was a problem that alignment stability and beam quality stability were poor.
(2) When the excitation light oscillated from the pulse laser is condensed by the lens, the energy density in the focal region becomes very high. As a result, a phenomenon occurs in which fine particles existing in the region cause dielectric breakdown and turn into plasma (this phenomenon is called laser breakdown).
When the breakdown occurs, the laser beam cannot be transmitted, and there is a problem that the laser output is reduced.
The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to improve alignment stability and beam quality stability, and to prevent a decrease in laser output due to breakdown. An optical pulse pulse width expander that can be provided, and a laser apparatus for discharge excitation exposure provided with the optical pulse width expander.

In the present invention, the above problems are solved as follows.
(1) Splitting the incident laser beam in a direction different from the incident direction of the laser beam so that an optical path difference occurs between the split optical element that splits the laser beam into a plurality of beams and a plurality of optical paths along which the divided laser beams travel. A delay optical system provided in each optical path through which light travels, and a combining optical system that synthesizes the divided laser beams so that each laser beam that has passed through the plurality of optical paths travels again through the same optical path In the optical pulse expander in which the optical path difference is set so that the laser pulse width of each synthesized laser beam is longer than the laser pulse width of the incident laser beam before being synthesized, An aperture that is disposed on the output side of the optical pulse expander and that forms a laser beam emitted from the optical pulse expander into a predetermined shape, and a laser beam that has passed through the aperture. A beam sampler for extracting a part of the light, a detector that receives the laser light from the beam sampler, monitors the energy of the incident laser light, and the optical pulse stretcher based on the output of the detector. And a control device for controlling the energy of the incident laser light.
(2) Splitting the incident laser beam in a direction different from the incident direction of the laser beam so that an optical path difference is generated between the split optical element that splits the laser beam into a plurality of beams and a plurality of optical paths along which the divided laser beams travel. A delay optical system provided in each optical path through which light travels, and a combining optical system that synthesizes the divided laser beams so that each laser beam that has passed through the plurality of optical paths travels again through the same optical path In the optical pulse expander in which the optical path difference is set so that the laser pulse width of each synthesized laser beam is longer than the laser pulse width of the incident laser beam before being synthesized, A beam sampler for taking out a part of the laser light that is disposed in the optical path formed by the delay optical system and passes through the optical path, and a laser from the beam sampler Is provided in at least two of a position sensor that detects the position of incident laser light and an optical element that constitutes the delay optical system, and a drive mechanism that drives an angle of the optical element with respect to the optical axis; A control device for controlling the drive mechanism is provided so that the position of the laser beam passing through the optical path becomes a predetermined position based on the position information of the position sensor.
(3) In the above (1) and (2), the window member through which the laser beam incident on the optical pulse stretcher and the laser beam output from the optical pulse stretcher pass is passed through the optical pulse stretcher. The container is accommodated in a sealed container provided, and a gas that does not easily cause vacuum evacuation or dielectric breakdown is sealed in the sealed container.
(4) In the above (1) and (2), the optical pulse expander includes a window member through which a laser beam incident on the optical pulse expander and a laser beam output from the optical pulse expander pass. A window member which is housed in a first sealed container provided and through which the laser light incident on the optical pulse stretcher and the laser light output from the optical pulse stretcher pass further. And a heating / cooling means for heating / cooling the atmosphere between the second sealed container and the first sealed container, which is housed in a second sealed container provided with a heat insulating material on at least a part of its outer surface. Based on the measurement result of a temperature sensor provided in the atmosphere between the second sealed container and the first sealed container, the ambient temperature between the second sealed container and the first sealed container is substantially constant. The heating and cooling means is controlled so as to hold The control means are provided.
(5) In the above (4), a gas that is not easily evacuated or causes dielectric breakdown is sealed in the first storage container.
(6) A laser chamber filled with a laser gas, a pair of discharge electrodes arranged in the laser chamber, a peaking capacitor connected in parallel with the pair of discharge electrodes, and a high-voltage pulse discharge in the laser chamber A high voltage pulse generator for exciting the laser gas to emit laser light, and a laser resonator having a narrow band module for narrowing the laser light, and the pair of discharge electrodes An exposure discharge excitation gas laser device connected to an output terminal of a magnetic pulse compression circuit mounted on the high voltage pulse generator, wherein the laser of the laser light emitted from the laser resonator is emitted to the exposure discharge excitation gas laser device. The optical pulse stretchers of the above (1), (2), (3), (4), and (5) are provided for extending the pulse width.
(7) The discharge-excited gas laser apparatus for exposure of (6) is any one of a KrF excimer laser apparatus, an ArF excimer laser apparatus, and a fluorine molecular laser apparatus.

In the present invention, the following effects can be obtained.
(1) Since an aperture for shaping the laser light emitted from the optical pulse stretcher into a predetermined shape is provided on the emission side of the optical pulse stretcher, due to thermal deformation of the optical pulse width stretcher, Even if misalignment occurs, beam profile deterioration can be prevented.
In addition, when a part of the laser beam that has passed through the aperture is taken out, the energy of the incident laser beam is monitored, and the energy of the laser beam incident on the optical pulse stretcher is controlled, so that the beam profile is deteriorated. Even if it exists, the output energy of a laser apparatus can be controlled uniformly.
(2) A part of the laser light passing through the optical path of the delay optical system of the optical pulse stretcher is extracted by a beam sampler, the position of the incident laser light is detected, and based on this position information, the optical axis of the optical element Since the position of the laser beam passing through the optical path is controlled to be a predetermined position by controlling the angle with respect to the beam, even if an alignment shift occurs due to thermal deformation of the optical pulse width expander, the beam Profile deterioration can be prevented.
(3) The optical pulse width expander is housed in the first sealed container, and the first sealed container is housed in a second sealed container in which a heat insulating material is provided on at least a part of the outer surface. Since the temperature in the atmosphere between the two sealed containers and the first sealed container is kept substantially constant, it is possible to prevent thermal deformation of the optical pulse width stretcher and to deteriorate the beam profile. Can be prevented.
(4) The optical pulse width expander of the above (1) to (3) is housed in a sealed container, and the sealed container is evacuated or filled with a gas that does not easily cause dielectric breakdown. A decrease in output can be prevented.

First, a configuration example of an exposure discharge excitation gas laser device (hereinafter also referred to as an exposure narrow-band laser device) provided with a narrow-band module as a premise of the present invention will be described.
FIG. 1 shows a configuration example of an exposure narrow band laser device using one or more magnifying prisms and a grating. FIG. 1 is a schematic diagram when the apparatus is viewed from above.
The laser chamber 101 is filled with a laser excitation medium gas (hereinafter referred to as laser gas). A high voltage pulse is applied to a pair of electrodes E (only one electrode is shown in FIG. 1) arranged opposite to each other in the laser chamber 101 from the high voltage pulse generator 102 by a predetermined distance. Discharge occurs in the meantime, and the laser gas in this discharge part is excited. Although not shown, a peaking capacitor is provided outside the laser chamber 101. The peaking capacitor is connected to a pair of electrodes E in parallel. The high voltage pulse from the high voltage pulse generator 102 is applied to the electrode E through a peaking capacitor.
Seed light that becomes a laser beam is generated from the excited laser gas. A fan 103 and a radiator (not shown) are further installed in the laser chamber 101. The laser gas is circulated in the laser chamber 101 by the fan 103, and the laser gas heated to high temperature by the discharge is heat-exchanged with the radiator and cooled. As shown in FIG. 1, the laser chamber 101 is provided with a window member 104 in the window portion at a C-shaped Brewster angle or a parallel Brewster angle. The electrode E includes an anode electrode and a cathode electrode that are separated from each other by a predetermined distance in the direction perpendicular to the paper surface.

The laser resonator is composed of a grating (diffraction grating) 105 a and an output mirror 106 mounted on a band-narrowing module 105 described later. The seed light that becomes the laser beam described above is taken out as a laser beam from the output mirror 106 by reciprocating between the grating (diffraction grating) 105a and the magnifying prism 105b installed in the band narrowing module 105, the discharge unit and the output mirror 106. . A part of the laser beam emitted from the output mirror 106 is introduced into the wavelength monitor 107 by the beam splitter 109, and the output, center wavelength, and the like are measured by the wavelength monitor 107.
The band narrowing is achieved by arranging an optical band narrowing module 105 having a spectroscopic function in the laser resonator. For example, the band narrowing module 105 includes a casing and a grating (diffraction grating) 105a and one or more magnifying prisms 105b installed in the casing, and a spectrum narrowing is realized by wavelength selection by the diffraction grating.
The oscillation center wavelength can be changed by rotating any one of the grating (diffraction grating) 105a and the magnifying prism 105b. It is also possible to change the oscillation center wavelength by installing a high reflection mirror at an arbitrary position between the laser chamber 101 and the grating 105a and rotating the high reflection mirror to change the incident angle of light to the diffraction grating. It is.
Based on the center wavelength signal from the wavelength monitor 107, the controller 108, as described above, the grating (diffraction grating) 105a and the magnifying prism 105b in the narrowband module 105 or the laser chamber 101 and the grating 105a (not shown). Wavelength control is performed by rotating any one of the high reflection mirrors installed at arbitrary positions.

In recent years, as described above, in the excimer laser for exposure (KrF excimer laser, ArF excimer laser) and the fluorine molecular laser, two lasers were used for improving the throughput of the exposure apparatus and realizing uniform ultrafine processing. A two-stage laser apparatus has been proposed (see Patent Document 3).
In the two-stage laser apparatus, the first oscillation stage laser has a narrow band spectrum with low pulse energy. In the second amplifying device, only the pulse energy is amplified while maintaining the ultra-narrow band spectrum of the oscillation stage laser.
Since this method does not include an optical loss due to a narrowband module (LNM) or the like in the second amplifying device, the laser oscillation efficiency is very high. Therefore, a desired narrow-band spectrum and output can be obtained by this two-stage laser system.
As a form of the above-described two-stage laser system, as an amplification device, an MOPA method using an amplifier having a laser chamber and not having a resonator mirror, and an amplification stage laser having a laser chamber and a laser resonator provided with a mirror are used. Broadly divided into MOPO systems.
The optical pulse width expander (OPS) of the present invention is arranged on the output side of the laser light emitted from the laser device 100 as shown in FIG. 2 when there is one laser device shown in FIG. The In the case of the two-stage laser device, it is arranged on the output side of the laser light emitted from the amplification device.

Hereinafter, the optical pulse width expander of the present invention will be described with reference to examples.
FIG. 3 is a diagram showing the configuration of the optical pulse width expander according to the first embodiment of the present invention.
In FIG. 3, reference numeral 10 denotes an OPS, and the OPS 10 includes a beam splitter 11, total reflection mirrors 12 a to 12 d, and a relay lens 13.
As shown in FIG. 3, the incident light is split by a beam splitter 11 and folded back in a direction orthogonal to the incident optical axis, and is reflected by a total reflection mirror 12a → lens 13 → total reflection mirror 12b → total reflection mirror 12c → lens 13 →. The light enters the beam splitter 11 through the path of the total reflection mirror 12d, is folded back in the same direction as the incident light by the beam splitter 11, is combined with the incident light, and is emitted from the beam splitter 11. On the emission side of the beam splitter 11, a slit 14 having the same opening as the beam size of the laser beam emitted from the OPS when the OPS is not thermally deformed is provided.

In the OPS having the above configuration, when the OPS main body is thermally deformed and the total reflection mirrors 12a to 12d are inclined, the light that passes through the beam splitter 11 (solid line in the figure) and the light that is reflected delayed (dotted line in the figure). Is out of position. In such a state, the beam profile output from the OPS becomes thicker than the original beam profile.
In the present embodiment, in order to prevent such a problem, as shown in FIG. 3, a slit 14 is provided to block only a thick portion. Thereby, the same profile as the incident beam can be obtained.
In addition, since the light blocked by the slit 14 becomes heat and further affects the deformation of the OPS and surrounding modules, it is desirable to provide a heat dissipation mechanism and a mechanism for keeping the temperature constant in the slit 14.

Further, when the slit 14 is provided as described above to block light, the energy that can be extracted as output decreases. Therefore, it is desirable to control the output of the laser device so that the energy that can be extracted as output is constant.
FIG. 4 shows a configuration example of a control system in the case where the output of the laser apparatus is controlled as described above.
In FIG. 4, reference numeral 100 denotes a gas laser device. As described above, the gas laser device 100 includes the fan 103, a radiator and a peaking capacitor (not shown), and a laser chamber 101 filled with laser gas, and a laser chamber 101. A high voltage pulse generator 102 for applying a high voltage pulse to the provided electrode E and a narrow band module 105 are provided.
When a high voltage pulse is applied from the high voltage pulse generator 102, a discharge is generated between the electrodes E, the laser gas is excited by this discharge, and seed light that becomes a laser beam is generated.
The above-described seed light that becomes a laser beam travels back and forth between a grating (diffraction grating) 105 a and one or more magnifying prisms 105 b, a discharge unit and the output mirror 106, which are installed in the narrowband module 105. Extracted as a beam. A part of the laser beam emitted from the output mirror 106 is introduced into the wavelength monitor 107 by the beam splitter 109, and the output, center wavelength, and the like are measured by the wavelength monitor 107. Based on the central wavelength signal from the wavelength monitor 107, the controller 108 controls the wavelength by rotating the grating (diffraction grating) 105a, the magnifying prism 105b, etc. in the narrowband module 105.

On the output side of the gas laser device 100, the OPS 10 having the slits 14 shown in FIG. 3 is provided.
A beam splitter 15 is provided on the light emitting side of the OPS 10, and a part of the light emitted from the OPS 10 is sampled by the beam splitter 15 and input to the energy monitor 111 to measure the output energy of the laser.
The energy controller 110 determines whether the laser output energy measured by the energy monitor 111 is a prescribed energy. As described above, the OPS main body undergoes thermal deformation, and the output of the laser is caused by a shift in the position of the light that passes through the beam splitter 11 (solid line in the figure) and the light that is delayed and reflected (broken line in the figure). When the energy deviates from the specified value, a signal for correcting the excess / deficiency is output to the high voltage pulse generator 102, and the output energy is controlled to be constant.

FIG. 5 is a diagram showing a configuration of an optical pulse width expander according to the second embodiment of the present invention. In this embodiment, the OPS mirror is moved to prevent misalignment due to thermal deformation of the OPS.
In FIG. 5, reference numeral 10 denotes an OPS, and the OPS 10 includes a beam splitter 11, total reflection mirrors 12 a to 12 d, and a relay lens 13.
As in FIG. 3, the incident light is split by the beam splitter 11 and folded back in the direction orthogonal to the incident optical axis, and the total reflection mirror 12a → lens 13 → total reflection mirror 12b → total reflection mirror 12c → lens 13 → all. The light enters the beam splitter 11 through the path of the reflection mirror 12d, is folded back in the same direction as the incident light by the beam splitter 11, is combined with the incident light, and is emitted from the beam splitter 11.
The total reflection mirrors 12b and 12c are provided with actuators 21 and 22 that are movable in two-axis tilt directions, respectively.
Further, the beam splitter 16 is installed before the delayed light beam reenters the beam splitter 11, and a part of the light enters the position detection sensor 23.

The position detection sensor 23 detects the position and / or direction of the incident beam, and this detection output is sent to the controller 24.
The controller 24 stores a position [target position] where light reflected by the beam splitter 11 and light transmitted through the beam splitter 11 overlap, and positions of the total reflection mirrors 12a to 12d of the OPS main body due to thermal deformation or the like. If the beam position / direction detected by the position detection sensor 23 deviates from the target position, the actuators 21 and 22 are driven so as to return the beam position / direction to the target position.
In the present embodiment, as described above, the position detection sensor 23 detects the beam position / direction, and when the beam position / direction is deviated, the total reflection mirrors 12b and 12c are moved to correct the beam position / direction. Therefore, even if the OPS is thermally deformed, deterioration of the beam profile can be prevented.

FIG. 6 is a diagram showing a configuration of an optical pulse width expander according to the third embodiment of the present invention. In this embodiment, the OPS is made into a sealed container and the periphery thereof is covered with a heat-controlled layer whose temperature is controlled, so that the temperature of the OPS is kept constant and misalignment is prevented.
In FIG. 6, reference numeral 10 denotes an OPS, and the OPS 10 includes a beam splitter 11, total reflection mirrors 12 a to 12 d, and a relay lens 13.
3 and 5, the incident light is divided by the beam splitter 11 and folded back in the direction orthogonal to the incident optical axis, and the total reflection mirror 12a → lens 13 → total reflection mirror 12b → total reflection mirror 12c → lens. The light enters the beam splitter 11 through the path 13 → total reflection mirror 12d, is folded back in the same direction as the incident light by the beam splitter 11, is combined with the incident light, and is emitted from the beam splitter 11.
The OPS 10 is housed in the first sealed container 31, and laser light incident on the OPS enters from the first window 31a, and emitted light from the OPS exits from the second window 31b.

The first sealed container 31 is housed in a second container 32 so as to cover the periphery of the first sealed container 31. The second container 32 is covered with a heat insulating wall and is hardly affected by heat from the outside. It is. The second container 32 is also provided with first and second windows 32a and 32b. The laser light incident on the OPS is incident on the first window 32a, and the light emitted from the OPS is the second light. The light is emitted from the window 32b.
There is a space between the second container 32 and the sealed container 31, and a gas heated or cooled by the heat exchanger 33 in this space is circulated by the fan 33a. A temperature sensor 34 is provided on the input side of the heat exchanger 33.
The temperature of the space measured by the temperature sensor 34 is fed back to the temperature controller 35, and the temperature of the space is controlled to be constant by the temperature controller 35.
Since the present embodiment has the above-described configuration, the OPS temperature can be kept almost constant, misalignment due to thermal deformation can be prevented, and deterioration of the beam profile can be prevented.
Note that this embodiment is applied to the first and second embodiments, and the OPS of the first and second embodiments is housed in a sealed container as described above, and the surroundings are temperature-controlled. The temperature of the OPS may be kept constant by covering with a heat insulating layer.

FIG. 7 is a diagram showing the configuration of an optical pulse width expander according to the fourth embodiment of the present invention. In this embodiment, the OPS is housed in a sealed container, and the inside of the sealed container is evacuated or sealed with a gas that does not easily cause dielectric breakdown, thereby preventing the breakdown described above. This embodiment is applied to the first to third embodiments. In the case of the third embodiment, the gas is sealed in the first sealed container 31.
In FIG. 7, reference numeral 10 denotes an OPS, and the OPS 10 includes a beam splitter 11, total reflection mirrors 12 a to 12 d, and a relay lens 13.
The incident light is divided by the beam splitter 11 in the same manner as in FIGS. 3, 5, and 6, and is folded back in the direction orthogonal to the incident optical axis, and the total reflection mirror 12 a → lens 13 → total reflection mirror 12 b → total reflection mirror. The light enters the beam splitter 11 through the path 12c → lens 13 → total reflection mirror 12d, is folded in the same direction as the incident light by the beam splitter 11, is combined with the incident light, and is emitted from the beam splitter 11.
The OPS 10 is housed in a sealed container 41, and a gas that causes dielectric breakdown is sealed in the sealed container 41. Alternatively, the sealed container 41 may be kept in a vacuum.
As in the third embodiment, the sealed container is provided with first and second windows 41a and 41b, and laser light incident on the OPS enters from the first window 41a and is emitted from the OPS. Exits from the second window 41b.
With the above-described configuration, breakdown can be prevented, and a decrease in laser output due to breakdown can be prevented.

It is a figure which shows schematic structure of the discharge excitation gas laser apparatus used as the premise of this invention. It is a figure explaining the installation position of the optical pulse expander of this invention. It is a figure which shows the structure of the optical pulse width expander of 1st Example of this invention. It is a figure which shows the structural example in the case of controlling a laser output in a 1st Example. It is a figure which shows the structure of the optical pulse width expander of the 2nd Example of this invention. It is a figure which shows the structure of the optical pulse width expander of the 3rd Example of this invention. It is a figure which shows the structure of the optical pulse width expander of the 4th Example of this invention.

Explanation of symbols

10 Optical pulse width expander (OPS)
DESCRIPTION OF SYMBOLS 11 Beam splitter 12a-12d Total reflection mirror 13 Relay lens 14 Slit 15 Beam splitter 21, 22 Actuator 23 Position detection sensor 24 Controller 31 1st sealed container 32 2nd sealed container 33 Heat exchanger 34 Temperature sensor 41 Sealed container 101 Laser chamber 102 High voltage pulse generator 103 Fan 104 Window member 105 Narrow band module 106 Output mirror 107 Wavelength monitor 108 Controller 109 Beam splitter 110 Energy controller 111 Energy monitor

Claims (7)

A splitting optical element that splits the incident laser light into a plurality of parts;
A delay optical system provided in each optical path in which the divided light travels in a direction different from the incident direction of the laser light, so that an optical path difference occurs between a plurality of optical paths in which each of the divided laser light travels;
It is composed of a synthesis optical system that synthesizes the divided laser beams so that each laser beam that has passed through the plurality of optical paths travels again on the same optical path, and the laser pulse width of each synthesized laser beam is synthesized An optical pulse stretcher in which the optical path difference is set to be longer than the laser pulse width of the incident laser light before being performed,
The optical pulse stretcher is further disposed on an emission side of the optical pulse stretcher, and an aperture that molds laser light emitted from the optical pulse stretcher into a predetermined shape, and laser light that has passed through the aperture A beam sampler to extract a part of
A detector that receives the laser beam from the beam sampler and monitors the energy of the incident laser beam;
An optical pulse stretcher comprising: a control device that controls energy of laser light incident on the optical pulse stretcher based on an output of the detector. A splitting optical element that splits the incident laser light into a plurality of parts;
A delay optical system provided in each optical path in which the divided light travels in a direction different from the incident direction of the laser light, so that an optical path difference occurs between a plurality of optical paths in which each of the divided laser light travels;
It is composed of a synthesis optical system that synthesizes the divided laser beams so that each laser beam that has passed through the plurality of optical paths travels again on the same optical path, and the laser pulse width of each synthesized laser beam is synthesized An optical pulse stretcher in which the optical path difference is set to be longer than the laser pulse width of the incident laser light before being performed,
The optical pulse stretcher is further arranged in an optical path formed by the delay optical system, and a beam sampler for taking out a part of the laser light passing through the optical path;
A position sensor that receives the laser beam from the beam sampler and detects the position of the incident laser beam;
A drive mechanism that is provided in at least two of the optical elements forming the delay optical system and drives an angle of the optical element with respect to the optical axis;
A control device that controls the drive mechanism based on the position information of the position sensor so that the position of the laser light passing through the optical path is a predetermined position;
An optical pulse stretcher characterized by the above. The optical pulse stretcher is housed in a sealed container provided with a window member through which a laser beam incident on the optical pulse stretcher and a laser beam output from the optical pulse stretcher pass,
The optical pulse stretcher according to claim 1 or 2, wherein a gas that hardly causes vacuum evacuation or dielectric breakdown is sealed in the sealed container. The optical pulse stretcher is housed in a first sealed container provided with a window member through which a laser beam incident on the optical pulse stretcher and a laser beam output from the optical pulse stretcher pass,
Further, the first sealed container is provided with a window member through which a laser beam incident on the optical pulse stretcher and a laser beam output from the optical pulse stretcher pass, and heat insulation is provided on at least a part of the outer surface. Housed in a second sealed container provided with materials,
Heating and cooling means for heating and cooling the atmosphere between the second sealed container and the first sealed container;
Based on the measurement result of the temperature sensor provided in the atmosphere between the second sealed container and the first sealed container, the ambient temperature between the second sealed container and the first sealed container is made substantially constant. 3. The optical pulse stretcher according to claim 1, further comprising control means for controlling the heating / cooling means so as to be held. 5. The optical pulse stretcher according to claim 4, wherein the first storage container is filled with a gas which is not easily evacuated or has a dielectric breakdown. A laser chamber filled with a laser gas; a pair of discharge electrodes disposed in the laser chamber; a peaking capacitor connected in parallel with the pair of discharge electrodes; and generating a high-voltage pulse discharge in the laser chamber. A high voltage pulse generator for exciting the laser gas to emit laser light, and a laser resonator having a narrow band module for narrowing the laser light, wherein the pair of discharge electrodes is the high voltage In the discharge-excited gas laser apparatus for exposure connected to the output terminal of the magnetic pulse compression circuit mounted on the pulse generator,
6. The exposure discharge excitation gas laser device according to claim 1, wherein the optical pulse expander according to claim 1, 2, 3, 4 or 5 for extending a laser pulse width of laser light emitted from the laser resonator. A discharge-excited gas laser device for exposure, comprising: 7. The discharge-excited gas laser apparatus for exposure according to claim 6, wherein the discharge-excited gas laser apparatus for exposure is any one of a KrF excimer laser apparatus, an ArF excimer laser apparatus, and a fluorine molecular laser apparatus.

Images