JP4683778B2 - Wavelength control device and control method for laser device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a technique for controlling the center wavelength of an excimer laser device to a desired target wavelength.
[0002]
[Prior art]
Conventionally, a wavelength control technique for narrowing a laser beam oscillated from an excimer laser device or the like and controlling its center wavelength to a desired value is disclosed in, for example, Japanese Patent Laid-Open No. 5-283785. FIG. 7 is a block diagram of the laser device disclosed in the publication, and the prior art will be described below with reference to FIG.
[0003]
In FIG. 7, an excimer laser device 11 includes a laser chamber 12 in which a laser gas that is a laser medium is sealed and windows 17 and 19 that transmit a pulse laser beam 21 are attached to both ends. Inside the laser chamber 12, a high voltage is applied between discharge electrodes (not shown), the laser gas is excited by pulse discharge, and pulsed laser light 21 is generated.
The generated pulsed laser light 21 enters the band narrowing unit 30, is magnified by the prism 32, is reflected by the wavelength selection mirror 34, and enters the grating 33 that is a band narrowing optical element. In the grating 33, only the pulsed laser light 21 having a wavelength near the predetermined center wavelength λc is reflected by diffraction. This is called narrowing the band.
[0004]
At this time, the wavelength selection mirror 34 is mounted on a movable holder 36 that is rotatable by the stepping motor unit 40. When the wavelength selection mirror 34 is rotated in a plane parallel to the paper surface, the incident angle of the pulse laser beam 21 with respect to the grating 33 changes, and the center wavelength λc of the pulse laser beam 21 diffracted by the grating 33 changes. That is, by rotating the wavelength selection mirror 34, it is possible to control the center wavelength λc of the oscillating pulsed laser light 21 to a desired target wavelength λ0.
[0005]
In addition, the excimer laser device 11 extracts a part of the pulsed laser light 21 with the beam splitter 22 and monitors the center wavelength λc of the pulsed laser light 21 with the wavelength monitor 37. The laser controller 29 outputs a command signal to the stepping motor unit 40 based on the monitored center wavelength λc, rotates the wavelength selection mirror 34, and controls the center wavelength λc of the pulsed laser light 21 to a desired target wavelength λ0. Yes. This is called wavelength control.
The narrow-band pulsed laser light 21 is amplified in the laser chamber 12 while reciprocating several times between the grating 33 in the narrow-band unit 30 and the front mirror 16 that partially reflects the pulsed laser light 21. Is done. Then, it is emitted forward (to the left of the paper surface in FIG. 7) as pulsed laser light 21 having a center wavelength λc, and enters an exposure device 25 such as a stepper.
[0006]
[Problems to be solved by the invention]
However, the prior art has the following problems.
In other words, when the excimer laser device 11 is used as an exposure light source for the exposure machine 25, it may be necessary to stop the laser oscillation for a certain period of time in order to replace the wafer or the reticle and stop the laser oscillation.
[0007]
In such a case, the optical component such as the prism 32 and the temperature around the optical component change, and the characteristics of the optical component change, or a fixing component (not shown) that fixes the optical component expands and contracts, so that the center wavelength is increased. λc may shift. Further, as a result of stopping the discharge for a while, the state of the discharge electrode or laser gas may change, and the center wavelength λc may shift. Such a shift in the center wavelength λc that occurs during a pause is referred to as a wavelength pause drift.
As a result, when the laser oscillation is resumed after the pause, the center wavelength λc of the oscillated laser beam 21 is greatly deviated from the target wavelength λ0, and it takes a long time to return it to the target wavelength λ0. .
[0008]
Further, for example, a wavelength change command for changing the target wavelength λ0 to λn may be output from the exposure unit 25 to the laser controller 29 during the pause. In such a case, at the time of re-oscillation, the difference between the center wavelength λc and the new target wavelength λn may be further increased, and in order to adjust the center wavelength λc to the new target wavelength λn, more There is a problem that it takes time.
As a result, the laser beam 21 having the center wavelength λc desired by the exposure unit 25 is not emitted, and the operating rate of the exposure unit 25 is reduced.
[0009]
The present invention has been made paying attention to the above problems, and provides a wavelength control device and a control method capable of quickly and accurately controlling the center wavelength of a pulse laser beam to a target wavelength after a pause. It is aimed.
[0010]
[Means, actions and effects for solving the problems]
  In order to achieve the above object, the present invention provides:
  Optical component rotating means for rotating the optical component by the drive mechanism to change the incident angle at which the pulse laser beam is incident on the narrow-band optical element;
  In the wavelength control device for a laser device comprising the laser controller that drives the optical component rotating means to change the incident angle and controls the center wavelength of the pulsed laser light to a predetermined target wavelength,
The optical component rotating means includes a first drive mechanism and a second drive mechanism that rotate the same optical component independently of each other,
The laser controller is
Based on the pause drift of the center wavelength that occurs during the pause of laser oscillation, the optical component is rotated during the pause by outputting a command to the first drive mechanism so that the center wavelength approaches the target wavelength,
When a wavelength change command for instructing the change of the target wavelength is received while the laser oscillation is stopped, the center wavelength approaches the new target wavelength based on the wavelength change command together with the output of the command to the first drive mechanism. To output a command to the second drive mechanism to rotate the optical component during the pause.
[0011]
According to such a configuration, two drive mechanisms are provided for correcting the pause drift and for changing the target wavelength. Thereby, the correction of the pause drift and the target wavelength change can be performed independently of each other at the same time, and the control is always performed without divergence.
[0012]
Also according to the invention,
The first drive mechanism is a piezoelectric element unit;
The second drive mechanism is a stepping motor unit.
Since the piezoelectric element unit is provided, not only correction of pause drift but also wavelength control during oscillation can be performed with high responsiveness by the piezoelectric element unit. Therefore, quick control is possible.
Further, the target wavelength λ0 can be changed over a wide band by changing the target wavelength λ0 with a stepping motor unit having a long stroke.
[0013]
Moreover, according to the present invention,
The first drive mechanism and the second drive mechanism are arranged in series.
As a result, the first and second drive mechanisms drive the same place of the same optical component, and therefore the degree of change in the center wavelength with respect to the drive amount of one drive mechanism is the driving degree of the other drive mechanism. It becomes irrelevant and always constant. Therefore, since the two drive mechanisms can be controlled independently of each other, the control becomes easy.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments according to the present invention will be described in detail with reference to the drawings.
FIG. 1 is a configuration diagram of an excimer laser device 11 according to the embodiment. In FIG. 1, an excimer laser device 11 includes a laser chamber 12 in which a laser gas that is a laser medium is sealed. A front window 17 and a rear window 19 that transmit the pulse laser beam 21 are attached to both ends of the laser chamber 12 by holders (not shown).
[0015]
Inside the laser chamber 12, a pair of discharge electrodes 14, 15 are installed facing the paper surface in FIG. A high voltage is applied between the discharge electrodes 14 and 15 from the high-voltage power source 23 to cause pulse discharge to excite the laser gas, and generate the pulsed laser light 21 at a frequency of, for example, several to several tens of kHz.
The generated pulse laser light 21 travels backward (leftward in FIG. 1), for example, and enters the band narrowing unit 30 that narrows the pulse laser light 21. The narrow band unit 30 is surrounded by a narrow band box 31 and includes prisms 32 and 32, a wavelength selection mirror 34, a grating 33, and the like as optical components. A purge gas supply port 35 is attached to the wall of the narrow-banding box 31, and a purge gas 45 having a low reactivity such as a clean and dry rare gas or high-purity nitrogen is introduced into the narrow-banding box 31. .
[0016]
The pulse laser beam 21 incident on the narrowband unit 30 is magnified by the prisms 32, 32, reflected by the wavelength selection mirror 34, and incident on the grating 33, which is a narrowband optical element. In the grating 33, only the pulsed laser light 21 having the center wavelength λc determined by the incident angle φ is reflected by diffraction.
At this time, the wavelength selection mirror 34 is mounted on a movable holder 36 that is rotatable in a horizontal plane (in a plane parallel to the paper surface in FIG. 1). By rotating the movable holder 36 and rotating the wavelength selection mirror 34, the incident angle φ of the pulsed laser light 21 incident on the grating 33 changes. As a result, the center wavelength λc of the pulsed laser light 21 diffracted by the grating 33 changes. In FIG. 1, 20 represents the laser optical axis of the pulse laser beam 21.
[0017]
The narrow-band pulsed laser light 21 is reciprocated several times between the grating 33 in the narrow-band unit 30 and the front mirror 16 that partially reflects the pulsed laser light 21. Is amplified by the discharge. Then, it partially passes through the front mirror 16, is emitted forward (to the right in FIG. 1) as pulsed laser light 21, and enters the exposure device 25. A part of the emitted pulsed laser light 21 is extracted downward in FIG. 1 by the beam splitter 22, and its center wavelength λc is monitored by the wavelength monitor 37.
[0018]
Hereinafter, the structure of the movable holder 36 according to the present embodiment will be described in detail.
FIG. 2 is a plan sectional view of the movable holder 36, and FIG. 3 is a front view of the movable holder 36 when the mirror side is viewed from the grating 33 side in the narrow band box 31.
As shown in FIGS. 2 and 3, the movable holder 36 includes a square mirror holder 38 to which the wavelength selection mirror 34 is fixed. The mirror holder 38 is attracted to the band narrowing box 31 by a biasing spring (not shown) and a biasing force of a leaf spring 49.
[0019]
Of the first to fourth corners 38A to 38D of the mirror holder 38, the second corner 38B and the first corner 38A are narrowed by the support member 39 and a manual micrometer 50 not shown in FIG. It is pressed from the banding box 31. The support member 39 has a screw 47 protruding from the narrow band box 31 by a predetermined length, for example, and is fixed by a nut 46. In addition, the manual micrometer 50 can freely change the protruding amount from the narrow band box 31 manually.
A piezo element unit 41 is attached to the third corner 38C of the mirror holder 38 as will be described later. The distal end portion 41B of the piezo element unit 41 is in contact with the ball screw unit 43 by an urging force of a pulling spring and a leaf spring 49 (not shown) and presses the stepping motor unit 40.
[0020]
As shown in FIG. 1, both the stepping motor unit 40 and the piezo element unit 41 are electrically connected to the laser controller 29. The stepping motor unit 40 rotates the motor shaft 48 (see FIG. 2) by a predetermined amount according to the number of pulses of the pulse signal received from the laser controller 29. A rear end portion 43B of a ball screw unit 43 in which a thread is precisely processed is attached to a front end portion 48A of the motor shaft 48 via a coupling 42. The ball screw unit 43 smoothly moves straight in the front-rear direction while rotating by the guide 51.
The tip portion 43A of the ball screw unit 43 is precisely machined into a plane perpendicular to the longitudinal direction, and the tip portion 41B of the piezo element unit 41 precisely machined into a spherical surface is in contact with this plane. Therefore, when the ball screw unit moves back and forth while rotating, the piezo element unit 41 moves back and forth without rotating. A rear end portion 41 </ b> A of the piezo element unit 41 is fixed to an ultraviolet cover 44 fixed to the mirror holder 38.
[0021]
The wiring 52 of the piezo element unit 41 passes through the inside of the ultraviolet cover 44, reaches the outside of the band narrowing box 31 through an introduction hole (not shown), and is connected to the laser controller 29. The piezo element unit 41 expands and contracts in the front-rear direction by a length corresponding to the magnitude of the voltage V applied via the wiring 52. The piezo element unit 41 is maintained at a neutral position of about ½ of the full stroke as an initial position.
[0022]
The laser controller 29 outputs a signal to the movable holder 36 to expand and contract the stepping motor unit 40 or the piezo element unit 41, thereby pushing and pulling the third corner 38 </ b> C of the mirror holder 38 through the ultraviolet cover 44. As a result, the wavelength selection mirror 34 rotates, the incident angle φ is changed, and the center wavelength λc of the pulse laser beam 21 changes.
At this time, based on the center wavelength λc monitored by the wavelength monitor 37, the laser controller 29 adjusts the center wavelength λc to the target wavelength λ0, and performs control so that the wavelength deviation which is the difference between the two becomes smaller than a predetermined allowable value. ing. This is called wavelength control.
[0023]
The laser controller 29 also controls the pulse output of the pulsed laser light 21 by outputting a voltage command to the high-voltage power supply 23 (this is called power lock control).
Further, the laser controller 29 communicates with the exposure unit 25 and performs laser oscillation based on an oscillation command signal from the exposure unit 25. In some cases, the laser controller 29 outputs an oscillation command signal based on its own judgment and performs laser oscillation.
[0024]
Hereinafter, a specific control procedure when the laser controller 29 uses the movable holder 36 to correct the wavelength pause drift and change the target wavelength λ0 during the pause will be described.
First, as a first control procedure, a case will be described in which a wavelength change command for instructing change of the target wavelength λ0 does not come during pause and only wavelength pause drift correction is performed.
[0025]
FIG. 4 shows, from above, the fluctuation of the center wavelength λc when the pause drift correction during pause is not performed, the oscillation command (ON / OFF) signal from the exposure unit 25, and the center wavelength λc when the pause drift correction is performed. 5 is a timing chart showing command voltages V output to the piezo element unit 41 when movement and pause drift correction are performed.
Note that the laser controller 29 performs wavelength control based on the center wavelength λc monitored by the wavelength monitor 37 during laser oscillation.
[0026]
As shown in FIG. 4, until time t11, the oscillation command signal is ON and laser oscillation is performed. The laser controller 29 outputs a command voltage V to the piezo element unit 41 based on the center wavelength λc monitored by the wavelength monitor 37 to perform wavelength control, and the center wavelength λc substantially matches the target wavelength λ0. .
At time t11, the oscillation command signal is turned off and the oscillation stops. Along with this, the center wavelength λc when the pause drift correction is not performed gradually moves in one direction due to a temperature change from time t11. Note that, here, the wavelength is described as drifting to the long wavelength side, but there may be cases where the wavelength drifts to the short wavelength side.
When laser oscillation is resumed at time t14, wavelength control is performed, the center wavelength λc approaches the target wavelength λ0, and returns to the target wavelength λ0 at time t16.
[0027]
On the other hand, when the pause drift correction is performed, the following control is performed.
When the laser oscillation pauses for a predetermined time or more, at time t12, the laser controller 29 estimates how much the center wavelength λc deviates from the target wavelength λ0 before the pause during the pause. This estimation is performed based on, for example, information on the pattern in which laser oscillation has been performed so far, the current temperature in the narrow band box 31, the rest time from time t11 to time t12, and the like. It is.
[0028]
The laser controller 29 corrects this shift, and immediately after the re-oscillation, the rotation angle of the wavelength selection mirror 34 for driving the center wavelength λc as close as possible to the target wavelength λ0, and the driving of the piezo element unit 41 for achieving this. Calculate the amount. Then, a voltage signal V corresponding to the calculated drive amount is output to the piezo element unit 41.
Thereby, the piezo element unit 41 drives the movable holder 36 from the time t12 to rotate the wavelength selection mirror 34, and the rotation ends at the time t13. As a result, the center wavelength λc approaches the target wavelength λ0, and the center wavelength λc substantially matches the target wavelength λ0 at time t13.
From time t11 to time t14, laser oscillation is not actually performed and monitoring cannot be performed. Therefore, the chart indicating the center wavelength λc is represented by a broken line.
[0029]
Thereafter, at time t14, laser oscillation is resumed. When the oscillation is resumed, the laser controller 29 controls the wavelength by outputting the command voltage V to the piezo element unit 41 based on the center wavelength λc monitored by the wavelength monitor 37. Thereby, at the time t15, the center wavelength λc substantially coincides with the target wavelength λ0.
That is, by making the center wavelength λc close to the target wavelength λ0 by the piezo element unit 41 in advance while the laser oscillation is stopped, the center wavelength λc can be quickly adjusted to the target wavelength λ0 after the oscillation is resumed. When such a pause drift correction is not performed, the center wavelength λc matches the target wavelength λ0 at time t16, which takes a lot of time.
[0030]
As described above, since the estimation of the shift amount of the center wavelength λc due to the pause drift is performed based on the pause time, the correction is performed again when the pause time becomes longer.
That is, in the above procedure, it is described that the piezo element unit 41 is moved only once and adjusted to the target wavelength λ0. However, the correction is usually performed by moving the piezo element unit 41 many times. Is doing.
[0031]
Next, as a second control procedure, a case will be described where a wavelength change command is issued so as to change the target wavelength λ0 from the exposure unit 25 during correction of pause drift.
FIG. 5 shows, from above, the fluctuation of the center wavelength λc when the pause drift correction during pause is not performed, the oscillation command (ON / OFF) signal from the exposure unit 25, pause drift correction, and the wavelength change command. 6 is a timing chart showing a center wavelength λc when it comes, a command voltage V output to the piezo element unit 41, a wavelength change command D, and a stroke position P of the stepping motor unit 40 in that case.
During oscillation, wavelength control is performed in the same manner as in FIG.
[0032]
As shown in FIG. 5, until time t21, the oscillation command signal is ON and laser oscillation is performed. The laser controller 29 performs wavelength control by outputting a command voltage V to the piezo element unit 41 based on the center wavelength λc monitored by the wavelength monitor 37, and the center wavelength λc substantially matches the target wavelength λ0.
At time t21, the oscillation command signal is turned off, and oscillation stops. Accordingly, the center wavelength λc when the pause drift correction is not performed gradually moves in one direction due to a temperature change from time t21. Here, the case where the wavelength drifts to the long wavelength side will be described as an example, but the wavelength may drift to the short wavelength side.
Then, when laser oscillation is resumed at time t27, wavelength control is performed. At this time, as will be described later, a wavelength change command for changing the target wavelength λ0 to a new target wavelength λn is output from the exposure unit 25 to the laser controller 29. Therefore, the laser controller 29 brings the center wavelength λc closer to the new target wavelength λn and matches the target wavelength λn at time t29.
[0033]
On the other hand, when the pause drift correction is performed, the following control is performed.
When the laser oscillation pauses for a predetermined time or more, at time t22, the laser controller 29 estimates how much the center wavelength λc deviates from the target wavelength λ0 before the pause during the pause. This estimation is performed based on, for example, information on the pattern in which laser oscillation has been performed so far, the current temperature in the narrow band box 31, and the rest time from time t21 to time t22. It is.
[0034]
Then, the laser controller 29 corrects this deviation, and immediately after re-oscillation, the rotation angle of the wavelength selection mirror 34 for making the center wavelength λc as close as possible to the target wavelength λ0, and the piezoelectric element unit 41 for achieving this. The driving amount is calculated. At time t22, a voltage signal V corresponding to the calculated drive amount is output to the piezo element unit 41.
Thereby, from time t22, the piezo element unit 41 drives the movable holder 36 and starts to rotate the wavelength selection mirror 34 in order to adjust the center wavelength λc to the target wavelength λ0.
[0035]
During this rotation, it is assumed that a wavelength change command D for changing the target wavelength λ0 to the new target wavelength λn comes from the exposure device 25 at time t24. The laser controller 29 outputs a command for changing the target wavelength λ0 to the stepping motor unit 40 from time t24 to time t25 while keeping the voltage command V for the piezo element unit 41 as it is. As a result, the stepping motor unit 40 moves from the stroke position P to Pn.
[0036]
During this time, the piezo element unit 41 continues to move according to the voltage command V, and reaches the target stroke at time t26.
In the above procedure, the piezo element unit 41 is moved only once to adjust to the target wavelength λ0. However, the correction is usually performed by driving the piezo element unit 41 repeatedly for a minute distance. Is doing. Therefore, while the piezo element unit 41 repeats operation and stop for several degrees, the stepping motor unit 40 continues to move and changes the target wavelength λ0.
Therefore, at time t26, the wavelength selection mirror 34 is rotated by a combination of the pause drift correction by the piezo element unit 41 and the change of the target wavelength λ0 by the stepping motor unit 40. As a result, the angle of the wavelength selection mirror 34 is substantially equivalent to the new target wavelength λn.
[0037]
When laser oscillation is resumed at time t 27, the laser controller 29 performs wavelength control based on the center wavelength λc monitored by the wavelength monitor 37. Since the center wavelength λc is close to the new target wavelength λn by the stepping motor unit 40 and the piezo element unit 41 during the pause, the center wavelength λc is set to the new target in a short time (at time t28). It can be adjusted to the wavelength λ0.
That is, when the target wavelength λ0 during the pause is not changed and the pause drift correction is not performed, the wavelength can be controlled very quickly compared with the case where the center wavelength λc matches the new target wavelength λn at time t29. .
[0038]
As described above, according to the present embodiment, pause drift correction is performed while laser oscillation is paused, and the shift of the center wavelength λc due to temperature change or the like is corrected so as to approach the target wavelength λ0 in advance. As a result, since the center wavelength λc quickly matches the target wavelength λ0 by the wavelength control after the oscillation is resumed, the laser light 21 having the center wavelength λc inappropriate for exposure deviating from the target wavelength λ0 is supplied to the exposure unit 25. Less incident. Further, the time required to obtain the laser beam 21 having the center wavelength λc suitable for exposure is short, and the operating rate of the exposure unit 25 is improved.
[0039]
Further, according to the present embodiment, the target wavelength λ 0 is changed based on the wavelength change command D from the exposure device 25 in addition to the pause drift correction during the pause of the laser oscillation. Thereby, the center wavelength λc quickly matches the new target wavelength λn by the wavelength control after the oscillation is resumed.
[0040]
Further, according to the present embodiment, the first drive mechanism (piezo element unit 41) for performing pause drift correction, and the second drive mechanism (stepping motor unit 40) for changing the target wavelength λ0. These two drive mechanisms are provided.
Therefore, even if a wavelength change command is input during pause drift correction, the laser controller 29 can perform each process independently without wondering which process should be preferentially performed. That is, the control is always performed without divergence.
That is, although the first drive mechanism has been described as the piezo element unit 41, the present invention is not limited to this. That is, both the first and second drive mechanisms may be stepping motor units, and both may be the piezo element unit 41.
[0041]
However, as described in the embodiment, it is preferable that the pause drift correction is performed by the piezo element unit 41 and the target wavelength λ0 is changed by the stepping motor unit 40.
That is, by changing the target wavelength λ0 by the stepping motor unit 40 having a long stroke, the target wavelength λ0 can be changed over a wide band.
[0042]
Further, pause drift correction must be performed every time laser oscillation is paused, and the frequency is high. Therefore, it is necessary to correct this with high accuracy, and accurate correction is possible by performing pause drift correction by the piezo element unit 41 that can drive a minute stroke more precisely.
Further, the first and second drive mechanisms are arranged in series, and one corner of the wavelength selection mirror 34 is pressed and rotated to control the center wavelength λc. However, the present invention is not limited to this. Absent. For example, the grating 33 and the prism 32 may be rotated.
[0043]
Further, for example, separate optical components may be rotated such that the wavelength selection mirror 34 is rotated by the stepping motor unit 40 and the prism 32 is rotated by the piezo element unit 41.
However, as described in the above embodiment, it is preferable that the stepping motor unit 40 and the piezoelectric element unit 41 are arranged in series and only one of the optical components is rotated. That is, since the first and second drive mechanisms drive the same place of the same optical component, the amount of change in the center wavelength with respect to the drive amount of one drive mechanism becomes independent of whether the other drive mechanism is driven, Always constant. Therefore, since the two drive mechanisms can be controlled independently of each other, the control becomes easy.
On the other hand, if the stepping motor unit 40 and the piezo element unit 41 are arranged at different locations, when one drive mechanism is driven, the drive amount required to change the center wavelength λc in the other drive mechanism. Is affected. That is, in order to change the center wavelength λc, the expansion / contraction amount of the piezo element unit 41 and the stepping motor unit 40 must be controlled in consideration of the mutual influence, which makes the control difficult.
[0044]
FIG. 6 shows an example in which the prism 32 is mounted on a rotatable movable holder 36 and the movable holder 36 is driven by a stepping motor unit 40 and a piezo element unit 41.
In this way, by using a configuration that does not use the wavelength selection mirror 34, the optical path length is shortened, so that the output is increased. For example, even in the case of an ArF excimer laser device with a small gain, an output with a necessary magnitude can be obtained. Oscillation is possible.
[0045]
According to the present invention, the wavelength control during laser oscillation is performed by the piezo element unit 41. Since the piezo element unit 41 has a short response time to the command, the responsiveness to the control is good, and the wavelength quickly matches the target wavelength λ0.
[0046]
In the description of the present embodiment, the new target wavelength λn is described as being on the longer wavelength side than the target wavelength λ0. However, the present invention is not limited to this. For example, the center wavelength λc may shift to the longer wavelength side due to pause drift, while the new target wavelength λn may be shorter than the target wavelength λ0. In such a case, the deviation due to the pause drift and the deviation due to the change of the target wavelength λ0 are added, so that the difference from the center wavelength λc to the new target wavelength λn is further increased.
Accordingly, when the pause drift correction and the change of the target wavelength λ0 according to the present invention are not performed, the time until the center wavelength λc matches the new target wavelength λn at the time t29 after the re-oscillation at the time t27. But longer. On the other hand, according to the present invention, since the center wavelength λc is approximately brought close to the new target wavelength λn during the downtime, rapid wavelength control is possible. In such a case, the effect of the present invention is achieved. But it gets bigger.
[0047]
Further, although the case where the grating 33 is used as the band narrowing optical element has been described, an etalon may be used.
Furthermore, although the present invention has been described with respect to an excimer laser device, the present invention can be similarly applied to a fluorine molecular laser device.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of an excimer laser device according to an embodiment.
FIG. 2 is a plan sectional view of the movable holder.
FIG. 3 is a front view of a movable holder.
FIG. 4 is a timing chart illustrating a first control procedure.
FIG. 5 is a timing chart illustrating a second control procedure.
FIG. 6 is a configuration example of an excimer laser device when a prism is driven.
FIG. 7 is a configuration diagram of an excimer laser device according to a conventional technique.
[Explanation of symbols]
11: Excimer laser device, 12: Laser chamber, 15: Discharge electrode, 16: Front mirror, 17: Front window, 19: Rear window, 20: Laser optical axis, 21: Laser light, 22: Beam splitter, 25: Exposure 29: Laser controller, 30: Narrow band unit, 31: Narrow band box, 32: Prism, 33: Grating, 34: Wavelength selection mirror, 35: Purge gas inlet, 36: Movable holder, 37: Wavelength Monitor: 38: Mirror holder, 39: Support member, 40: Stepping motor unit, 41: Piezo element unit, 42: Coupling, 43: Ball screw unit, 44: UV cover, 45: Purge gas, 46: Nut, 47: Screw 48: motor shaft, 49: leaf spring, 50: manual micrometer 51: guide, 52: wiring.

Claims (4)

Optical component rotating means for rotating the optical component by the drive mechanism and changing the incident angle (φ) where the pulse laser beam (21) is incident on the narrow-band optical element (33),
A laser controller (29) for driving the optical component rotating means to change the incident angle (φ) and controlling the center wavelength (λc) of the pulsed laser beam (21) to a predetermined target wavelength (λ0). In the wavelength control device for a laser device,
The optical component rotating means includes a first drive mechanism (41) and a second drive mechanism (40) that rotate the same optical component independently of each other,
The laser controller (29)
Based on the pause drift of the center wavelength (λc) that occurs during the pause of laser oscillation, a command is output to the first drive mechanism (41) so that the center wavelength (λc) approaches the target wavelength (λ0). Rotate the optical components inside,
When a wavelength change command for instructing the change of the target wavelength (λ0) is received while the laser oscillation is suspended, the center wavelength (based on the wavelength change command is output together with the output of the command to the first drive mechanism (41). A wavelength control device for a laser device , wherein a command is output to the second drive mechanism (40) so that λc) approaches a new target wavelength (λn), and the optical component is rotated during a pause . The wavelength control device for a laser device according to claim 1,
The first drive mechanism (41) is a piezoelectric element unit;
The wavelength control device for a laser device, wherein the second drive mechanism (40) is a stepping motor unit. The wavelength control device for a laser device according to claim 1 or 2,
The wavelength control device for a laser device, wherein the first drive mechanism (41) and the second drive mechanism (40) are arranged in series. The optical component is rotated with respect to the laser optical axis (20) by the drive mechanism to change the incident angle (φ) of the pulsed laser light (21) to the narrow band optical element (33),
In the wavelength control method of the laser device for controlling the center wavelength (λc) of the pulse laser beam (21) to a predetermined target wavelength (λ0),
Using a first drive mechanism (41) and a second drive mechanism (40) that rotate the same optical component independently of each other;
A command is output to the first drive mechanism (41) so that the center wavelength (λc) approaches the target wavelength (λ0) based on the shift of the center wavelength (λc) that occurs during the suspension of laser oscillation. Rotate the optical components,
When a wavelength change command for instructing the change of the target wavelength (λ0) is received while the laser oscillation is stopped, the center wavelength (based on the wavelength change command is output together with the output of the command to the first drive mechanism (41). A wavelength control method for a laser device, comprising: outputting a command to the second drive mechanism (40) so that λc) approaches a new target wavelength (λn) to rotate the optical component during the pause.

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