JP2000156535A - Injection locked narrow-band pulse laser system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make the life of optical elements longer, increase the locking efficiency and the spectrum purity and maintain stable laser output. SOLUTION: When a synchronous oscillation pulse signal TR and an energy instruction value E are inputted from an aligner controller 31 to a laser controller 41, the laser controller 41 sends the synchronous oscillation pulse signal TR to the oscillator stage delay processing part 43 and the amplifying stage delay part 51, and sends a voltage instruction value V0 to the amplifying stage power supply 45. The oscillator stage delay processing part 43 adds a trigger to the oscillator stage power supply 44 with unique delay time, allows the oscillator stage 10 to oscillate and makes harmonic light A incident into the amplifying stage 20. The delay time calculating part 53 calculates real delay time Tre of the amplification stage power supply 45 in the magnetic pulse compression circuit based on the voltage instruction value V0 and the temperature data from the sensor 47, and obtains the delay time τ by subtracting the real delay time Tre from the time sent from the reference delay time setting part 51 Tds. The amplifying stage delay part 51 starts energy transfer in the magnetic pulse compression circuit and synchronize the oscillator stage 10 and the amplification stage 20 after the delay time τ.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection-lock type narrow-band pulse laser device, and more particularly to appropriately adjusting the light emission timings of an oscillator stage and an amplification stage regardless of an output change and environmental changes. The present invention relates to an injection-lock type narrow-band pulse laser device capable of performing the above-described operation.

[0002]

2. Description of the Related Art Conventionally, in a narrow band KrF excimer laser, when 248 nm ultraviolet laser light is pulsed, a part of output laser light is taken out, a laser output and a laser wavelength are detected, and wavelength control and output control are performed. Had gone.

For example, FIG. 19 shows a schematic configuration of a conventional narrow band excimer laser. In this narrow band excimer laser, a laser gas filled in a laser chamber 101 is excited by pulse discharge of a discharge electrode 102. Laser oscillation is performed by a resonator constituted by the front mirror 105 and the rear mirror 104, and the laser output light LA is output from the front mirror 105. Part of the laser output light LA is extracted by the beam splitter 106 and input to the wavelength monitor 107. In the wavelength monitor 107, the beam splitter 107e, the etalon 107b, the lens 1
The interference fringes of the laser output light LA input via the input line 07c are captured by the line sensor 107d, and the result is input to the wavelength controller 108. The wavelength monitor 107
The reference light 107a near the wavelength of the laser output light LA
The reference light 107a is output through a beam splitter 107e, an etalon 107b, and a lens 107c. An interference fringe of the reference light 107a is captured by a line sensor 107d and input to a wavelength controller 108. The wavelength controller 108 calculates the wavelength of the laser output light from the interference fringe of the input laser output light and the interference fringe of the reference light, calculates the wavelength shift from the target wavelength, and based on the calculation result, Via the driver 109,
The wavelength selection element 110 in the band narrowing module 103 is driven to control the wavelength to a desired oscillation wavelength. The wavelength of the laser output light LA is controlled to the target wavelength by such feedback control.

On the other hand, an oscillator stage for generating a narrow band laser beam is connected to an amplification stage for amplifying the laser beam, and a synchronous injection for outputting a narrow band laser beam having a large output from the amplification stage. An (injection lock) type pulse laser is known, and a laser beam having a narrow band can be obtained by using the injection lock type pulse laser (Japanese Patent Application Laid-Open No. 63-54786).
No.).

[0005] Further, in the exposure apparatus, the wavelength can be further shortened due to the requirement that the ultrafine processing can be performed more precisely.
There is a demand for a laser device capable of oscillating an ultraviolet laser beam having a stable output capable of performing fine processing.

[0006] For this reason, as shown in FIG. 20, for example, an injection lock type pulse laser using a solid-state laser has been studied. This injection-lock type pulse laser can output laser light having a wavelength of 193 nm. That is, the Nd: YAG laser 1
The narrow band titanium sapphire laser 122 is oscillated using the second harmonic (532 nm) of the laser light oscillated by the laser 21 as pumping light, and the oscillated 773.6 nm laser light is quadrupled by the wavelength converter 123. 193 nm). Then, this laser light L
B1 is connected to the amplification stage 1 via the total reflection mirrors 131 and 132.
24 and output as amplified laser light LB2. In the amplification in the amplification stage 124, the discharge electrode 126 is discharged in synchronization with the laser oscillation of the oscillator stage 120, and the laser light LB1 input into the chamber 125 filled with the laser excitation gas is converted into the convex mirror 127 and the concave mirror 128. This is performed by amplifying light by stimulated emission until the light is passed through and output. by this,
A 193 nm laser beam with a narrow band can be obtained.

In the injection-lock type pulse laser shown in FIG. 20, if the wavelength of long-wavelength light is selected and the wavelength is monitored, the narrow-band pulsed laser light can be output to a processing apparatus such as an exposure apparatus. The problems that occur in the conventional single-type excimer laser shown in FIG. 19 are as follows: (1) If the wavelength is shortened, such as the oscillation wavelength (193 nm) of the ArF excimer, a durable appropriate base material and coating are obtained. There is no material. For example,
Even with a fluoride crystal material such as fluorite (CaF2), there is a problem in durability, and AR or HR such as an antireflection film is used.
Coats also have durability problems.

(2) When the wavelength is short, such as the oscillation wavelength (193 nm) of the ArF excimer, it is difficult to detect the wavelength and the line width with high accuracy. Specifically, there is no reference light source suitable for the wavelength of 193 nm. In addition, there is no absorption line suitable for the wavelength of 193 nm.
Furthermore, a high-precision etalon for 193 nm cannot be manufactured. Furthermore, there is no durability of the wavelength monitor itself. Such a problem can be solved.

Incidentally, an injection lock type pulse laser is used as a light source for a semiconductor exposure apparatus, and the light source is required to have a very high spectral purity. This is because no matter how thin the line width is, the higher the background light, the worse the resolution of the lens in the semiconductor exposure apparatus.

Here, FIG. 21 is a diagram for explaining the spectral purity. The spectral purity is expressed as: spectral purity (%) = (area within the range of wavelength ± δλ)
/ (Total area) * 100.

On the other hand, it is necessary to maintain the locking efficiency as high as about 95% or more and stably. Here, FIG.
It is a figure for explaining locking efficiency, and locking efficiency can be represented by locking efficiency (%) = N / (A + N) * 100. Here, N is a narrowband light component, and A is a spontaneous emission component.

In the case of an injection-lock type pulse laser, assuming that the spectrum of the narrow-band light N is very small, the spectral purity and the locking efficiency are almost the same.

However, the conventional injection-lock pulse laser cannot satisfy the above-described spectral purity and locking efficiency, and cannot be used as a light source for a semiconductor exposure apparatus. This is because 1) the timing at which the oscillator stage oscillates and the timing at which the amplifier stage oscillates 2) a miss shot occurs. That is, when the light from the oscillator stage is not injected into the amplifier stage and the amplifier stage emits light, only the spontaneous emission component A is output. 3) The light emission pulse width of the oscillator stage 120 and the amplification stage 124 fluctuates. 4) The oscillator stage The light intensity and the light emission pulse width of the amplifier stage 120 and the amplification stage 124 have not been optimized. 5) The laser output of the oscillator stage 120 is not stable.

In general, when the oscillator stage 120 is an ArF excimer laser, a timing chart from the trigger of the oscillator stage for causing the oscillator stage 120 to emit light to the stage of emitting light from the amplification stage 124 is as shown in FIG. That is, the triggering of the oscillator stage 120 occurs at time T1
At the time T1, the oscillator stage 120
Is discharged, and the excitation of the discharge causes the oscillator stage 120 to emit light and be injected into the amplifier stage 124 during the period TO from the time T2. During the emission of the oscillator stage 120, a trigger is applied to the amplification stage 124 at a time T3 having a predetermined delay time, and the amplification stage 124 discharges. The discharge stage is excited by the discharge, and the amplification stage 124 emits light during the period Ta from the time point T4. Here, the trigger delay time from the application of the trigger of the oscillator stage 120 to the application of the trigger of the amplification stage 124 is (T3-T1), and the emission delay time is (T3).
4-T2). Note that the light emission period To of the oscillator stage 120 is shorter than the light emission period Ta of the amplification stage 124.

When the locking efficiency of the injection-lock type pulse laser operating at such timing is examined, the relationship shown in FIG. 24 is obtained. Here, the light emission period TO is 10 ns, and the light emission period Ta is 20 ns.
ns. FIG. 24 shows the energy of the oscillator stage 120 injected into the amplification stage 124 as a parameter, and from this relationship, the energy of the oscillator stage 120 injected into the amplification stage 124 is equal to or more than a predetermined value, here 5
It can be seen that the locking efficiency cannot be maintained high unless it is 7 μJ or more. In addition, the delay time (T
It can be seen that the locking efficiency cannot be maintained high unless 4-T2) is operated in the range of 20 ns to 60 ns.

FIG. 25 is a graph showing the delay time (T4−T4) using the injection energy of the oscillator stage 120 as a parameter.
T2) shows the relationship between the relative output of the amplification stage 124 and
From this relationship, the value of the delay time (T4-T2) is 22 ns.
Energy efficiency is high in the vicinity, and this delay time (T4-T
If it is not in the range of 2), the stability of the laser output from the amplification stage 124 cannot be maintained.

In the case where a discharge excitation type excimer laser is used as an oscillator stage, even if a trigger for discharge is actually applied to the oscillator stage, jitter, that is, the oscillator stage emits light after an electrical trigger is applied. Since the variation in the time until this is very large, it is difficult to use this discharge excitation type excimer laser as an oscillator stage.

In the case of a discharge excitation type excimer laser, it is difficult to make the emission pulse width of the oscillator stage 10 ns or more. That is, in order to increase the emission pulse width, it is necessary to increase the discharge time, and if the discharge time is increased, the discharge is disturbed and laser oscillation stops.

Therefore, as shown in FIG. 20, an injection-lock type pulse laser using a titanium sapphire laser 122 and a wavelength converter 123 as the oscillator stage 120 has been proposed. Of about 90% and low spectral purity, and cannot be used as a light source for a semiconductor exposure apparatus. This is because the emission pulse width of the Nd: YAG laser 121 as the pumping laser is short (10 ns or less), and therefore, the injection light L output from the titanium sapphire laser 122 and the wavelength conversion unit 123.
This is because the pulse width of B1 also becomes very short. As a result, the delay time (T4-T2) could not be maintained within an allowable range, and the spectral purity and the stability of pulse energy could not be maintained at a high level.

For this reason, various oscillator stage lasers whose emission pulse width can be adjusted by the oscillator stage 120 have been proposed.

[0021]

However, even in the case of an injection lock type pulse laser which can appropriately adjust a light emission pulse width to a desired value as an oscillator stage,
As long as a discharge excitation type excimer laser is used as the amplification stage, there is a problem that high spectral purity and stable pulse energy cannot be maintained.

That is, since the life of a trigger switch using a thyratron is short in a recent discharge excitation type excimer laser, a laser source combined with a solid-state switch such as a GTO and a plurality of magnetic switches is mainly used. The timing from the trigger input by the solid state switch to the actual discharge through the magnetic switch greatly changes depending on the charged voltage and temperature, and the change in the discharge timing of this amplification stage significantly deteriorates the locking efficiency. Even if an appropriate delay time (T4−T2) was set, high spectral purity and stable pulse energy could not be maintained in continuous operation.

In particular, when performing continuous pulse oscillation (burst mode oscillation) by using the light source as a light source of a semiconductor exposure apparatus, a spiking phenomenon occurs in which the laser pulse output in the initial stage of the continuous pulse oscillation increases, and this spiking phenomenon occurs. In order to solve the problem, the charging voltage and the like are set low and stable continuous laser pulse oscillation is always performed. However, the setting control to keep the charging voltage and the like low causes the discharge timing to be delayed. In general, during burst mode oscillation, pulse energy control is also performed for each pulse, so that the discharge timing also changes due to this adjustment control, and high locking efficiency and stable pulse energy cannot be output.

In addition, since the semiconductor exposure apparatus performs continuous pulse oscillation, it is necessary to control the energy to be constant. In some cases, the pulse width time interval of the continuous pulse oscillation is designated to be the same. In some cases, control of time intervals must also be accommodated.

Here, in the laser power supply that performs the above-described pulse compression, a phenomenon in which a discharge timing, that is, a light emission timing is shifted due to a change in a charging voltage or the like, will be described in detail.

FIG. 26 shows an equivalent circuit of a general capacity transfer type magnetic pulse compression discharge device. Also. FIG. 27 shows an example of voltage and current waveforms in each section of the circuit of FIG.

The discharge circuit shown in FIG. 26 is a two-stage magnetic pulse compression circuit utilizing the saturation phenomenon of three magnetic switches AL0 to AL2 composed of saturable reactors.

First, when the first laser oscillation trigger signal is received, an energy command value E or a power supply voltage value V0 of a laser power supply is input from an exposure apparatus (not shown), and a laser controller (not shown) outputs this energy. Is calculated, and the voltage of the high-voltage power supply HV is adjusted based on the calculated value. At this time, the capacitor C0 is precharged with the electric charge from the high voltage power supply HV via the magnetic switch AL0 and the coil L1.

Thereafter, when the pulse oscillation synchronizing signal (trigger signal) TR is received for the first time from the exposure apparatus side, the main switch SW is turned on at the time of this reception (FIG. 27, time t0). When the main switch SW is turned on, the main switch S
The potential VSW of W rapidly drops to 0, and thereafter, the capacitor C0, which is the voltage across the magnetic switch AL0, and the main switch S0.
When the time product (time integral value of the voltage VCO) S0 of the potential difference VCO-VSW of W reaches a limit value determined by the setting characteristics of the magnetic switch AL0, the magnetic switch AL0 saturates at this time t1, and the capacitor C0 and the magnetic switch AL0 The current pulse i0 flows through the loop of the main switch SW and the capacitor C1.

The time δ0 from when the current pulse i0 starts flowing to when it becomes 0 (time t2), that is, the charge transfer time δ0 until the charge is completely transferred from the capacitor C0 to the capacitor C1, is the main switch SW. If the loss due to the above is ignored, the capacitor C0 and the magnetic switch AL
0, which is determined by each capacitance and inductance of the capacitor C1.

On the other hand, when the time product S1 of the voltage VC1 of the capacitor C1 reaches a limit value determined by the setting characteristics of the magnetic switch AL1, the magnetic switch AL1 saturates at time t3 to have a low impedance. As a result, a current pulse i1 flows through the loop of the capacitor C1, the capacitor C2, and the magnetic switch AL1. The current pulse i1 becomes 0 at time t4 after a predetermined transfer time δ1 determined by the capacitances and inductances of the capacitors C1 and C2 and the magnetic switch AL1.

When the time product S2 of the voltage VC2 of the capacitor C2 reaches a limit value determined by the setting characteristics of the magnetic switch AL2, the magnetic switch AL2 saturates at time t5, whereby the capacitor C2, the peaking capacitor CP, A current pulse i2 flows through the loop of the magnetic switch AL2.

Thereafter, the voltage VCp of the peaking capacitor Cp rises with the progress of charging, and when this voltage VCp reaches a predetermined main discharge starting voltage, at time t6, the laser gas between the main electrodes 206 is broken down and the main discharge is started. Is started. The laser medium is excited by the main discharge, and a laser beam is generated after several nsec.

Thereafter, the voltage of the peaking capacitor Cp rapidly decreases due to the main discharge, and returns to a state before the start of charging after a predetermined time has elapsed.

By repeating such a discharging operation by the switching operation of the main switch SW synchronized with the trigger signal TR, pulse laser oscillation at a predetermined repetition frequency (pulse oscillation frequency) is performed.

According to the magnetic compression circuit of FIG. 26, since the inductance of the charge transfer circuit of each stage composed of the magnetic switch and the capacitor is set so as to become smaller as it goes to the subsequent stage, the current pulses i0 to i2 A pulse compression operation is performed such that the peak value is gradually increased and the conduction width is gradually narrowed. As a result, a strong discharge can be obtained between the main discharge electrodes 206 in a short time. Further, since the magnetic switches AL0 to AL2 are reset to the initial state by the reset circuit of the saturable reactor for each pulse, the saturation point (operating point) of each magnetic switch AL0 to AL2 is set to even the voltage. If they are the same, they will be constant over each pulse.

However, in the above magnetic compression circuit, when the initial charging voltage V0 changes, the saturation times σ0, (σ0 + σ1), and (σ1 + σ2) of the magnetic switches AL0 to AL2 determined by the voltage-time product change accordingly. Accordingly, the time td from the time t0 when the trigger signal TR is input and the main switch SW is rolled to the time t6 when the laser light is actually generated also changes.

The discharge (light emission) timing of the amplification stage changes due to the change of the time td, and the locking efficiency deteriorates.

Therefore, the present invention eliminates the above-mentioned problems, prolongs the life of an optical element, has high locking efficiency and high spectral purity, and can obtain a stable laser output with an injection lock type pulse laser. The purpose is to provide.

[0040]

According to a first aspect of the present invention, there is provided an oscillator stage for oscillating a first pulse laser beam having a narrow band at a first timing, and a second pulse using a magnetic pulse compression circuit. Discharge excitation at the timing of
An amplification stage that stimulates and emits the second pulse laser light as injection light and outputs the amplified second pulse laser light;
In the injection-lock type narrow-band pulse laser device having synchronization control means for appropriately adjusting the timing of the second timing and the second timing, the synchronization control means uses the second pulse laser light to perform a predetermined operation. Delay time setting means for setting a fixed delay time from the oscillation instruction sent from the processing device performing the processing to the second timing in accordance with the first timing; Delay time calculating means for predicting and calculating an actual delay time from the start of energy transfer of the magnetic pulse compression circuit to the second timing based on a parameter, and calculating a delay time obtained by subtracting the actual delay time from the fixed delay time; Energy transfer of the magnetic pulse compression circuit after a delay time calculated by the delay time calculation means from the oscillation instruction has elapsed. Characterized by comprising an energy transfer start means for starting.

According to the first aspect of the present invention, the delay time setting means outputs the second pulse laser beam from an oscillation instruction from a processing apparatus such as an exposure apparatus, corresponding to the first timing of the oscillator stage. The fixed delay time is set to be always constant until the start of energy transfer is controlled so that the discharge of the amplification stage is performed after the fixed delay time elapses. Even when the energy transfer time of the magnetic pulse compression circuit that changes due to the change in the energy value that regulates the output of the device, the synchronization between the first timing and the second timing is always properly controlled, and the locking efficiency and the spectral purity And it is possible to maintain a stable pulse energy.

Further, since the second pulse laser beam is always obtained after a fixed delay time from the oscillation instruction, the use of the second pulse laser beam on the processing apparatus side is facilitated. Further, since the injection-lock type narrow-band pulse laser device is used, the load on the optical element for narrow band can be reduced, and the life of the optical element and the like can be significantly extended.

According to a second aspect of the present invention, the first narrowed band is provided.
The pulsed laser light is excited at a second timing by using an oscillator stage that oscillates the pulsed laser light at a first timing and a magnetic pulse compression circuit, and the first pulsed laser light is stimulated emitted as injection light and amplified. The injection-locked narrow-band pulse laser device, comprising: an amplification stage that outputs a second pulse laser beam; and a synchronization control unit that appropriately synchronizes the first timing and the second timing. The control means includes a magnetic switch operation sensor for detecting when a magnetic switch used on the magnetic pulse compression circuit is turned on, and the second pulse from the start of energy transfer of the magnetic pulse compression circuit based on a parameter related to laser output. The actual delay time until the timing is predicted and calculated, and the first timing corresponding to the second timing based on the predicted calculation is calculated. Delay time calculating means for calculating a delay time for delaying the oscillation of the oscillator stage to achieve, and oscillator stage oscillation delay means for performing the oscillation of the oscillator stage after adding the delay time calculated by the delay time calculating means. It is characterized by having.

In the invention according to claim 2, the delay time calculating means calculates the actual delay time in the magnetic pulse compression circuit,
Since the first timing in the oscillator stage is appropriately controlled based on the calculation result, the magnetic pulse compression circuit which changes according to an environmental change such as temperature or a change in the energy value defining the output from the amplifier stage. Even if the energy transfer time changes, the synchronization between the first timing and the second timing is always properly controlled, the locking efficiency and the spectral purity are high, and the operation and effect of maintaining stable pulse energy can be achieved. Play.

In particular, since the first timing is controlled by the magnetic switch operation sensor from the time when the magnetic switch close to the discharge electrode is actually turned on, the time error can be reduced, and more accurate synchronization timing control is performed. be able to.

Further, since the injection-lock type narrow-band pulse laser device is used, the load on the optical element for narrow band can be reduced, and the life of the optical element and the like can be greatly extended.

According to a third aspect of the present invention, the first band narrowed band is provided.
The pulsed laser light is excited at a second timing by using an oscillator stage that oscillates the pulsed laser light at a first timing and a magnetic pulse compression circuit, and the first pulsed laser light is stimulated emitted as injection light and amplified. The injection-locked narrow-band pulse laser device, comprising: an amplification stage that outputs a second pulse laser beam; and a synchronization control unit that appropriately synchronizes the first timing and the second timing. The control means corresponds to a fixed delay time from an oscillation instruction sent from a processing device that performs a predetermined processing process using the second pulsed laser beam to the second timing, in correspondence with the first timing. Delay time setting means for setting the time, a magnetic switch operation sensor for detecting when a magnetic switch used on the magnetic pulse compression circuit is on, A first delay time obtained by predicting and calculating an actual delay time from the start of energy transfer of the magnetic pulse compression circuit to the second timing based on a parameter related to an output, and subtracting the actual delay time from the fixed delay time A delay time calculating means for calculating energy transfer; and an energy transfer starting means for starting energy transfer of the magnetic pulse compression circuit after a lapse of a first delay time calculated by the first delay time calculating means from the oscillation instruction. Calculating a real delay time from the start of energy transfer of the magnetic pulse compression circuit to the second timing based on a parameter related to a laser output, and a first timing corresponding to a second timing based on the prediction calculation Second delay time calculating means for calculating a second delay time for delaying the oscillation of the oscillator stage to generate Serial second delay time calculating means, characterized by comprising the oscillator stage oscillating delay means for causing the oscillation of the oscillator stage after the second delay plus the time time was calculated.

According to the third aspect of the present invention, the delay time setting means outputs the second pulse laser beam from an oscillation instruction from a processing apparatus such as an exposure apparatus, corresponding to the first timing of the oscillator stage. The fixed delay time is set to be always constant until the start of the energy transfer is controlled so that the discharge of the amplifier stage is performed after the fixed delay time has elapsed, and the actual delay in the magnetic pulse compression circuit is also controlled on the oscillator stage side. Since the time is calculated and the first timing in the oscillator stage is appropriately controlled based on the calculation result, the first timing changes depending on environmental changes such as temperature and a change in the energy value defining the output from the amplification stage. Even if the energy transfer time of the magnetic pulse compression circuit changes, the synchronization between the first timing and the second timing is always properly controlled,
The effect is that locking efficiency and spectral purity are high and stable pulse energy can be maintained.

In particular, since the first timing is controlled by the magnetic switch operation sensor from the time when the magnetic switch close to the discharge electrode is actually turned on, the time error can be reduced, and more accurate synchronization timing control can be performed. It can be carried out.

Further, since the second pulse laser beam is always obtained after a fixed delay time from the oscillation instruction, the use of the second pulse laser beam on the processing apparatus side is facilitated. Further, since the injection-lock type narrow-band pulse laser device is used, the load on the optical element for narrow band can be reduced, and the life of the optical element and the like can be significantly extended.

The invention according to claim 4 is the invention according to claims 1 to 3, further comprising a temperature sensor for detecting a temperature of the magnetic pulse compression circuit, and converting the temperature detected by the temperature sensor into the laser output. It is characterized in that it is used as a related parameter.

According to the fourth aspect of the invention, the temperature of the magnetic pulse compression circuit is detected as a parameter related to the laser output. The prediction calculation can be performed accurately, and the synchronization between the first timing and the second timing can be appropriately controlled.

[0053]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing an entire configuration of an injection lock type pulse laser according to a first embodiment of the present invention, and FIG. 2 is a timing chart of signals of respective parts in the injection lock type pulse laser shown in FIG. .

In FIG. 1, the injection lock type pulse laser is mainly composed of an oscillator stage 10 and an amplification stage 20.

The oscillator stage 10 has a narrow-band fundamental wave laser 1 and a wavelength converter 6, and the narrow-band fundamental wave laser 1
Has an amplification medium 4 excited by an oscillator stage power supply 44, and the light emitted by the amplification medium 4 is filtered by a wavelength selection element 3 into light of a predetermined band, and the wavelength selection element 3 and a front mirror 5 The laser oscillates in the optical resonator formed between the two, and outputs the fundamental wave light L as laser light from the front mirror 5 to the wavelength conversion unit 6.

The wavelength converter 6 converts the input fundamental light L into the same wavelength as the output light LB finally output, and outputs the converted light as harmonic light LA. For example, the fundamental light L
Is 773.6 nm, the wavelength conversion unit 6 converts the fundamental light L into a four-fold harmonic by sum frequency mixing.
It is converted into a laser beam of 93.4 nm. This wavelength converter 6
Is realized by a wavelength conversion element having a nonlinear optical effect. For example, using three non-linear optical elements, the first non-linear optical element generates laser light of input wavelengths ω and 2ω, and the second non-linear optical element generates laser light of wavelengths ω and 3ω (ω + 2ω). Then, laser light having the wavelength ω and 4ω (ω + 3ω) is generated by the next nonlinear optical element, and the laser light having the wavelength 4ω is transmitted using a spectroscopic element such as a dichroic mirror or a prism that transmits the laser light. This harmonic light LA is input to the amplification stage 20 via the total reflection mirrors 7 and 8.

The chamber 21 of the amplification stage 20 is filled with ArF gas capable of generating, for example, 193 nm laser light, and has a discharge electrode 24 for exciting this ArF gas to an excimer state. The discharge at the discharge electrode 24 is performed by the amplification stage power supply 45. The input harmonic light LA is applied to the coupling hole 2 of the concave mirror 22.
2 ′, and is input into the chamber 21 via the convex mirror 2
3 and further reflected by the concave mirror 22 and output as output light LB. The harmonic light LA is applied to the chamber 21
By performing optical amplification by stimulated emission while reciprocating inside, harmonic light LA is output as amplified output light LB. Then, the output light LB is input to the illumination optical system 33 of the exposure apparatus 30, and a part of the output light LB1 is extracted by the energy monitor 40 to monitor the energy Ea of the output light LB.

The exposure apparatus controller 31 of the exposure apparatus 30
Inputs an oscillation pulse synchronization signal TR, an energy command E or a power supply voltage value VO of a laser power supply to a laser controller 41 on an injection lock type pulse laser side, and outputs a pulse laser of output light LB from the injection lock type pulse laser. The oscillating timing and its output are instructed, and the exposure device 30 is controlled.

The laser controller 41 converts the oscillation pulse synchronizing signal TR input from the exposure apparatus controller 31 into an oscillator stage delay processing section 43 and an amplification stage delay processing section 4.
2 to the amplification stage delay unit 51 and the amplification stage power supply 4 based on the energy value Ea of the energy monitor 40 and the energy command E required by the exposure apparatus controller 31.
5 is output to the oscillator stage delay processor 43 and the delay time calculator 53 of the amplifier stage delay processor 42.

After the input of the oscillation pulse synchronizing signal TR, the oscillator stage delay processing section 43 outputs the oscillator stage trigger signal TO delayed by a predetermined delay time Tdo to the oscillator stage power supply 44.
Output from the oscillator stage 10, and the narrowed fundamental wave laser 1 of the oscillator stage 10.
Oscillates the fundamental light L, and injects the harmonic light LA into the amplification stage 20 via the wavelength converter 6. This fundamental light L is
After the trigger of the oscillator stage trigger signal TO is applied to the amplifying medium 4, the light is emitted after the lapse of the oscillator stage delay time Tos from the oscillation pulse synchronization signal TR, and is emitted during the period Tb. The delay time from the input of the trigger signal TO until the oscillator stage 10 actually emits light is a unique value determined by the characteristics of the solid-state laser used as the oscillator stage 10.

Voltage command value V input to amplification stage power supply 45
Based on 0, the amplification stage power supply 45 performs charging so as to have a voltage corresponding to the voltage command value V0. The amplification stage power supply 45 is formed of, for example, a magnetic pulse compression circuit as shown in FIG. 26, and a voltage corresponding to the voltage command value V0 is stored and charged in the capacitor C0.

The amplification stage delay processing section 42 includes an amplification stage delay section 5
1, reference delay time setting section 52, and delay time calculation section 5
3

The reference delay time setting section 52 sets the amplification stage reference delay time Tds. This amplification stage reference delay time Tds
Is a time from the oscillation pulse synchronizing signal TR to the discharge of the amplification stage power supply 45, and is set to discharge for a period Ta after a predetermined time after the oscillator stage delay time Tos. The output light LB emits light after the amplification stage reference delay time Tds. The period Tb of the oscillator stage light emission is a period including the discharge period Ta of the amplification stage, whereby the locking efficiency and the laser output are output stably.

Therefore, when the oscillator stage delay time Tos is a fixed time, the amplification stage reference delay time Tds becomes longer than the oscillator stage delay time Tos and the period Tb becomes longer than the period Ta. Must always be constant. Therefore, the above-described amplification stage delay setting unit 52 sets the amplification stage reference delay time Tds. Therefore, the amplification stage reference delay time Tds is a set time that changes according to the length of the oscillator stage delay time Tos.

Since the amplification stage power supply 45 uses a magnetic pulse compression circuit, the energy transfer time varies depending on the change in the voltage command value V0 or the environment of the amplification stage power supply, for example, the temperature. Must be adjusted so that the discharge timing of the amplification stage power supply 45 can always be discharged after the amplification stage reference delay time Tds from the oscillation pulse synchronization signal TR.

For this reason, the delay time calculation unit 53 calculates the temperature data from the sensor 47 for detecting the temperature of the magnetic pulse compression circuit and the voltage command value V from the laser controller 41.
0, the actual delay time Tre from the application of the amplification stage trigger TRL until the actual discharge is performed is calculated based on the temperature data and the voltage command value V0, and the actual delay time Tre is calculated from the amplification stage reference delay time Tds. A time τ obtained by subtracting the actual delay time Tre is calculated, and this time τ is output to the amplification stage delay unit 51.

The amplification stage delay unit 51 applies the amplification stage trigger TRL to the switch 46 of the amplification stage power supply 45 after the lapse of the time τ input from the delay time calculation unit 53 from the oscillation pulse synchronizing signal TR, and performs energy transfer. The discharge is started after the actual delay time Tre calculated by the delay time calculator 53.
The switch 46 corresponds to, for example, the switch SW in the magnetic pulse compression circuit of FIG.

As a result, the oscillator stage emission emits light during the period Tb after the oscillation pulse synchronizing signal TR and after the oscillator stage delay time Tos, and the amplification stage discharge emits the oscillation pulse synchronization signal TR.
Thereafter, the discharge is always performed for the period Ta after the amplification stage reference delay time Tds, and the light emission of the oscillator stage 10 and the amplification stage 20
The timing with the discharge (light emission) is synchronized with high accuracy. As a result, a stable laser output with high locking efficiency and high spectral purity can be obtained.

Next, an injection lock type pulse laser according to a second embodiment of the present invention will be described with reference to FIGS. FIG. 3 is a diagram showing the overall configuration of an injection-lock type pulse laser according to a second embodiment of the present invention, and FIG. 4 is a timing chart of signals of various parts in the injection-lock type pulse laser shown in FIG. .

In the first embodiment, the oscillator stage delay time Tos is fixed, and the application timing of the amplification stage trigger TRL is controlled in accordance with the change in the energy transfer time of the amplification stage power supply. Although the light emission timing of the amplification stage 20 and the light emission timing of the amplification stage 20 are controlled, in the second embodiment, the amplification stage delay time Td corresponding to the amplification stage delay time Tds is set to the variable time set to the same time as the actual delay time Tre. And the oscillator stage delay time T
By adjusting o, the application timing of the oscillator stage trigger TO, which should synchronize the light emission timing of the oscillator stage 10 with the amplification stage discharge timing, is to be controlled.

First, the laser controller 41 outputs the voltage command value V0 of the amplification stage power supply 45 based on the energy value Ea of the energy monitor 40 and the energy command E requested by the exposure device controller 31, or
Receiving the laser power supply voltage command VO from the side, the amplification stage power supply 45 performs charging so as to have a voltage corresponding to the voltage command value V0. On the other hand, the voltage command value V0 is input to the delay time calculator 61 of the oscillator stage delay processor 43.

Further, the laser controller 41 outputs the oscillation pulse synchronizing signal TR input from the exposure apparatus controller 31 to the amplification stage power supply 45 and, as the amplification stage trigger TRL, immediately after the transmission pulse synchronizing signal TR is input, the magnetic pulse compression circuit. Is started, and the charged energy is transferred to the discharge electrode 24. This transfer time is
It is the amplification stage delay time Td and the actual delay time Tre.

The amplification stage power supply 45 has a magnetic switch operation sensor 48. This magnetic switch operation sensor 48
This is a sensor that detects the saturation of the saturable reactor used in the magnetic pulse compression circuit, for example, any one of the saturable reactors AL1 and AL2 in FIG. 27, and its configuration will be described later.

For example, if the magnetic switch operation sensor 48 detects the saturation of the saturable reactor AL1,
The magnetic switch operation sensor 48 outputs the detection time to the oscillator stage delay unit 62 of the oscillator stage delay processing unit 43. This detection time is the time Tm from the oscillation pulse synchronization signal TR. This time Tm is equal to the voltage command value V0.
And changes with temperature.

The delay time calculation unit 61 determines whether the magnetic switch operation sensor 48 is based on the voltage command value V 0 input from the laser controller 41 and the temperature data from the sensor 47 for detecting the temperature of the magnetic pulse compression circuit. Calculate the time Tdm from the time of detection to the appropriate oscillator stage oscillation,
A time τ2 is calculated by subtracting the oscillator stage delay time Tdo unique to the oscillator stage power supply 44 from this time Tdm, and this time τ2 is output to the oscillator stage delay unit 62. That is, the oscillation synchronization accuracy is improved by adding a time τ2 for absorbing the fluctuation of the amplification stage delay time Tds to the oscillator stage delay time Tdo for achieving the oscillation synchronization.

The oscillator stage delay section 62 outputs the oscillator stage trigger signal TO to the oscillator stage power supply 44 after a time Tdm obtained by adding the time τ2 to the oscillator stage delay time Tdo from the time point when the magnetic switch operation sensor 48 detects.

That is, in the second embodiment, the time at which the magnetic switch is operated in the magnetic pulse compression circuit is reliably detected, and the time at which the output light LB is emitted is more reliably determined. This is to precisely synchronize with the light emission. That is, in the second embodiment, the time error generated in the magnetic pulse compression circuit is reduced by controlling the magnetic switch operation near the discharge electrode 24 as a starting point.

As a result, the light emitted from the oscillator stage is synchronized with the light emitted from the amplification stage. As a result, the locking efficiency and the spectral purity are high, and a stable laser output can be obtained.

Next, an injection lock type pulse laser according to a third embodiment of the present invention will be described with reference to FIGS. FIG. 5 is a diagram showing an entire configuration of an injection lock type pulse laser according to a third embodiment of the present invention, and FIG. 6 is a timing chart of signals of respective parts in the injection lock type pulse laser shown in FIG. .

In the third embodiment, in addition to the light emission synchronization between the oscillator stage 10 and the amplification stage 20 in the second embodiment, the time from the oscillation pulse synchronization signal TR to the final emission of the amplification stage 20 is obtained. In the same manner as in the first embodiment.

First, the laser controller 41 calculates a voltage command value V0 calculated based on the energy value Ea of the energy monitor 40 and the energy command E required by the exposure apparatus controller 31, or a voltage directly transmitted from the exposure apparatus controller 31. The command value V0 is output to the amplification stage power supply 45, the delay time calculation unit 53 of the amplification stage delay processing unit 42, and the delay time calculation unit 61 of the oscillator stage delay processing unit 43, and the oscillation pulse synchronizing signal TR is processed by the amplification stage delay process. The signal is output to the amplification stage delay unit 51 of the unit 42.

The amplification stage power supply 45 is connected to the laser controller 4.
The battery is charged based on the voltage command value V0 input from Step 1.

The reference delay time setting unit 52 sets the amplification stage delay time Tds from the oscillation pulse synchronization signal TR until the amplification stage discharge is performed, and outputs the same to the delay time calculation unit 53. The amplification stage delay time Tds is constant, so that the amplification stage 20 has a constant time after the input of the oscillation pulse synchronization signal TR.
Will output the output light LB. It should be noted that the oscillator stage 10
Oscillator stage delay time To
Is also constant.

The delay time calculating section 53 calculates the voltage command value V 0 inputted from the laser controller 41 and the amplification stage power supply 45.
Based on the temperature data from the sensor 47, the actual delay time Tre from the application of the amplification stage trigger TRL to the discharge of the amplification stage 20 is calculated, and the actual delay time Tre is calculated from the amplification stage delay time Tds which is a fixed time. A time τ1 obtained by subtracting the delay time Tre is calculated, and this time τ1 is output to the amplification stage delay unit 51.

The amplification stage delay unit 51 converts the oscillation pulse synchronizing signal TR input from the laser
However, the delayed amplification stage trigger TRL is applied to the switch 46 of the amplification stage power supply 45 to start energy transfer.

On the other hand, as in the second embodiment, the amplification stage power supply 45 has a magnetic switch operation sensor 48, detects the saturation time of a predetermined saturable reactor, and uses this time as the oscillator stage delay processing unit. The signal is output to the oscillator stage delay unit 62 of the reference numeral 43.

The delay time calculation unit 61 of the oscillator stage delay processing unit 43 determines the magnetic switch based on the voltage command value V 0 input from the laser controller 41 and the temperature data input from the sensor 47 of the amplification stage power supply 45. Motion sensor 4
8, an appropriate time Tdm from the point of detection of the oscillation to the oscillation of the oscillator stage is calculated.
Time τ2 obtained by subtracting 4 inherent oscillator stage delay time Tdo
And outputs this time τ2 to the oscillator stage delay unit 62. Here, the oscillator stage delay time Tdo and the time τ2
Has the same technical significance as in the second embodiment.

The oscillator stage delay unit 62 outputs the oscillator stage trigger signal TO to the oscillator stage power supply 44 after a time Tdm obtained by adding the time τ2 to the oscillator stage delay time Tdo from the time when the magnetic switch operation sensor 48 detects.

As a result, the oscillator stage light emission is synchronized with the amplification stage light emission, so that locking efficiency and spectral purity are high, a stable laser output can be obtained, and output light LB is output from application of the oscillation pulse synchronization signal TR. It is possible to make the time until it is constant. In the present embodiment, it is also possible to calculate the actual delay time Tre based on the laser power supply voltage value and the temperature of the magnetic pulse compression circuit, and output the oscillator stage trigger signal TO based on the calculated value. However, the actual delay time Tre obtained by such calculation includes an error, and in terms of strict oscillation synchronization between the oscillator stage 10 and the amplification stage 20, as described in the third embodiment, the magnetic switch sensor It is more desirable to use the control to obtain the time Tdm.

Here, a specific configuration of the magnetic switch operation sensor 48 according to the second and third embodiments will be described.

FIG. 7 is a diagram showing an arrangement of the magnetic switch operation sensor 48 on the magnetic pulse compression circuit.
7, the magnetic switch operation sensor 48 detects the saturation point of the saturable reactor AL1, and outputs a detection signal Sa to the oscillator stage delay unit 62.

Since the magnetic switch operation sensor 48 detects the temperature of the magnetic pulse compression circuit as a parameter related to the laser output, the energy transfer time accompanying the temperature change of the magnetic pulse compression circuit due to continuous oscillation or the like can be reduced. The prediction calculation can be performed accurately, and the synchronization of the light emission timing of the oscillator stage 10 and the amplification stage 20 can be appropriately controlled.

FIGS. 8 to 12 are diagrams showing specific examples of the magnetic switch operation sensor 48. FIG. In FIG. 8, a magnetic core (or coil) 72 as an inductance means is connected in series with the saturable reactor (magnetic switch) AL1. As shown in FIG. 8A, an induced voltage vs is generated in the magnetic core 72 by self-induction due to a current change of the current pulse i1, and by detecting this induced voltage vs, the rising point t3 of the current pulse i1 is detected. (Corresponding to time point t3 in FIG. 27)
Can be detected.

In FIG. 9, the induced electromotive voltage vs (see FIG. 9B) induced in the secondary winding 73 of the magnetic switch AL1 is detected, and based on this voltage detection, the rising point t3 of the current pulse i1 is determined. I try to detect.

In FIG. 10, a primary coil 74 is connected in series to the magnetic switch AL1, and a secondary coil 7 generated by a current change of a current pulse i0 flowing through the primary coil 74.
5, the induced voltage vs. 5 is detected, and the rising point t3 of the current pulse i1 is detected based on the detected voltage.

In FIG. 11, the air-core coil 77 in the reset circuit 76 of the magnetic switch AL1 (circuit for setting the BH characteristic of the magnetic switch to a predetermined initial state) is connected, and the induced voltage vs. of the air-core coil 77 is detected. Then, the rising point t3 of the current pulse i1 is detected based on the voltage detection.

In FIG. 12, a capacitor C1 is connected in parallel with a resistor.
r1 and r2 are connected, and the rising point t3 of the current pulse i1 is detected based on the detection of the divided voltage vs.

In the meantime, the sensor 47 in the first to third embodiments is a temperature sensor, and detects the temperature of the insulating oil of the magnetic switch by a thermocouple or the like. Alternatively, the function of this temperature sensor can be realized by combining a magnetic switch operation sensor.

FIG. 13 is a diagram showing a configuration in which the functions of the sensor 47 and the magnetic switch operation sensor 48 are realized by two magnetic switch operation sensors 48a and 48b.

That is, the magnetic switch operation sensor 48a
Detects the saturation operation of the magnetic switch AL1 in the same manner as the magnetic switch operation sensor 48, and the magnetic switch operation sensor 48b detects the magnetic switch A preceding the magnetic switch AL1.
When the saturation operation of L0 is detected, the magnetic switch operation sensor 48
a and the magnetic switch operation sensor 48b
Is sent to the delay time calculator 62.
The delay time calculation unit 62 calculates a value corresponding to the temperature data from the time difference between the detection signals Sa and Sb, calculates the time τ2 in consideration of the voltage command value V0, and calculates the oscillator stage delay unit 62. Output to Therefore, a value corresponding to the temperature data can be obtained by the two magnetic switch operation sensors 48a and 48b.

On the other hand, the magnetic switch operation sensor 48a has the same function as the magnetic switch operation sensor 48, and the detection signal Sa of the magnetic switch operation sensor 48a is sent to the oscillator stage delay unit 62, and the detection signal Sa Delay processing is performed based on the time point.

As described above, even if the temperature is not actually detected without providing the sensor 47 as the temperature sensor, a value corresponding to the temperature data can be obtained by combining the magnetic switch operation sensors.

The above-described delay time calculation units 53 and 61
Uses temperature data, but without using this temperature data, a certain degree of synchronization can be achieved, so if the permissible value is large, it is not necessary to use temperature data. Can be deleted.

The above-described delay time calculation units 53 and 61
May calculate the time τ, τ1, τ2 using a table. That is, τ, τ1, τ2 calculated in advance corresponding to the voltage command value V0 and the temperature data may be immediately converted and output. In this case, high-speed output is possible. In particular, in the second and third embodiments,
Further, it is possible to detect the operation of the magnetic switch near the discharge electrode 24 side, and it is possible to achieve more accurate synchronization.

The injection-lock type pulse laser described above has a titanium sapphire laser (773.6n) as the narrow-band fundamental wave laser 1 in the oscillator stage 10.
Although the case where m) is used has been described, as shown in FIG. 14, this titanium sapphire laser is actually optically pumped by a pumping pulse laser PL. As the pumping pulse laser PL, specifically, the second harmonic (532 nm) of a YAG laser or the second harmonic (527 nm) of a YLF laser is used. The oscillator stage trigger signal TO is transmitted from the unit 43.

Further, a specific configuration of an injection lock type pulse laser to which the first to third embodiments are applied will be described with reference to FIG.

In FIG. 15, the output light of the narrow band CW titanium sapphire laser or the narrow band CW semiconductor laser is further amplified by a pulsed titanium sapphire laser amplification stage 80 and input to the wavelength conversion section 6, where the wavelength conversion is performed. A configuration in which the harmonic light from the section 6 is input to the amplification stage 20 is an injection lock type pulse laser.

That is, in the oscillator stage 10, first, C
A W (continuous oscillation) laser beam is oscillated. This includes
A CW titanium sapphire laser or a CW semiconductor laser is used. In the case of a CW titanium sapphire laser, an argon ion laser (multiline of 488 nm, 515 nm, etc.) PL1 is used as the pumping CW laser. Pumping C for CW semiconductor laser
The W laser PL1 is unnecessary. The CW laser light from the CW laser 81 is applied to a titanium sapphire laser amplification stage 80.
And pulsed by the pumping pulse laser PL2. This titanium sapphire laser amplification stage 8
0 is specifically realized by a ring resonator or the like. Then, the fundamental light L (773.6 nm) of the pulse output from the titanium sapphire laser amplification stage 80 is input to the wavelength conversion unit 6, and the harmonic light LA as the fourth harmonic is output.
(193.4 nm) is input to the amplification stage 20.

The advantage of using the CW laser 81 is that
This is because a single mode laser beam having a very narrow spectrum width can be obtained because the laser is used. However, since the light intensity of the laser light from the CW laser is very low, the laser light is amplified by the titanium sapphire laser amplification stage 80 into a very strong pulsed laser light.
As described above, the pumping pulse laser PL2
In practice, the second harmonic of a YAG laser or a YLF laser can be used.

With such a configuration, a pulse laser beam having a narrow band can be obtained with a high output.

Here, the case where the light emission pulse width of the laser light injected from the oscillator stage 10 is changed will be described.

FIG. 16 is a diagram showing a measurement relation of laser emission by the injection lock type pulse laser according to the present invention. When an oscillator stage trigger signal TO is input from the laser controller 41 to the oscillator stage power supply 44 via the oscillator stage delay processing section 43, the oscillator stage power supply 44
Excites a rod (not shown) of a YLF (or YAG) laser as the pumping pulse laser PL, and the pumping pulse laser PL outputs a laser beam of 1054 (1064) nm with a predetermined light emission pulse width. This laser light is converted into second harmonic light (536n
m) is converted into laser light. The method of adjusting the emission pulse width of the laser light is realized by changing the gain, the resonator length, the Q value, or the pulse waveform of the Q switch driver of the YLF (YAG) laser.

The second harmonic light excites a titanium sapphire rod, which is the amplification medium 4 of the narrow band titanium sapphire laser 1a as the narrow band fundamental wave laser 1, emits light with a predetermined light emission pulse width, and emits light with a wavelength of 773. The laser light with a narrow band of 0.6 nm is output as the fundamental light L. The fundamental light L is converted by the wavelength converter 6 into the fourth harmonic light LA (19).
3.4 nm) and output as harmonic light having a predetermined light emission pulse width.

A part of the harmonic light LA is extracted by the beam splitter 91 and detected by the optical sensor 93. On the other hand, the harmonic light LA transmitted through the beam splitter 91 is input to the amplification stage 20. Here, the amplification stage 20 discharges and amplifies and outputs by the synchronous control realized by the above-described first to third embodiments. A part of the output light LB is extracted by the beam splitter 92,
The light is detected by the optical sensor 94.

The light sensor 93 measures the light emission timing, light emission pulse width and pulse energy of the injected harmonic light LA, and the light sensor 94 outputs the output light LB.
The light emission timing, the light emission pulse width and the pulse energy can be measured, and the spectral purity can be measured.
The emission pulse width of the narrow band titanium sapphire laser 1a can be controlled by changing the resonator and the Q value of the YLF laser serving as the pumping pulse laser PL. Further, by converting the laser light by the wavelength conversion units 90 and 6, the pulse width of the injection light can be controlled at an arbitrary timing. Further, by adjusting the delay of the oscillator stage delay processing unit 43 and the amplification stage delay processing unit 42, it is possible to control the input of the injection light and the excitation timing of the amplification stage 20 at an arbitrary timing.

Here, the relationship between the pulse width of the injected light (harmonic light LA) and the spectral purity is measured, as shown in FIG.

From FIG. 17, it can be seen from FIG. 17 that, by increasing the pulse width of the injection light, the allowable range of the delay time of the injection timing at which the spectral purity can be maintained high is about the same as the length of the pulse width of the injection light. It can be seen that the length can be increased.

This means that the spectral purity does not deteriorate even if the timing of the injection light and the excitation of the amplification stage slightly changes due to the jitter, because the allowable range of the delay time extends.

FIG. 18 shows the relationship between the pulse width and the pulse energy of the injected light. From FIG. 18, it is understood that when the pulse width of the injection light becomes longer, the allowable range in which the amplified pulse energy is stable can be made as long as the length of the pulse width of the injection light becomes longer.

This means that the pulse energy of the amplification stage can be stably maintained even if the injection timing of the injection light and the excitation stage of the amplification stage change due to the extended delay time allowable range.

In the above embodiment, the solid-state laser is used as the laser in the oscillator stage. This is because the solid-state laser can more stably emit the injection light. If a stable output can be obtained even by using a gas laser or a liquid laser, the oscillator can be used as an oscillator stage. For example, it is possible to use an excimer laser capable of performing a stable laser output while maintaining a constant power supply voltage and temperature, and it is needless to say that the present invention is not limited to a solid-state laser.

[Brief description of the drawings]

FIG. 1 is a diagram showing an overall configuration of an injection lock type pulse laser according to a first embodiment of the present invention.

FIG. 2 is a timing chart of signals of respective parts of the injection lock type pulse laser shown in FIG.

FIG. 3 is a diagram illustrating an entire configuration of an injection-locked pulse laser according to a second embodiment of the present invention.

4 is a timing chart of signals of respective parts of the injection lock type pulse laser shown in FIG.

FIG. 5 is a diagram showing an overall configuration of an injection-lock type pulse laser according to a third embodiment of the present invention.

6 is a timing chart of signals of respective parts of the injection lock type pulse laser shown in FIG.

FIG. 7 is a diagram showing an arrangement configuration of a magnetic switch operation sensor on a magnetic pulse compression circuit.

FIG. 8 is a diagram showing a specific example of a magnetic switch operation sensor.

FIG. 9 is a diagram showing a specific example of a magnetic switch operation sensor.

FIG. 10 is a diagram showing a specific example of a magnetic switch operation sensor.

FIG. 11 is a diagram showing a specific example of a magnetic switch operation sensor.

FIG. 12 is a diagram showing a specific example of a magnetic switch operation sensor.

FIG. 13 is a diagram showing a configuration in which the functions of a sensor 47 and a magnetic switch operation sensor 48 are realized by two magnetic switch operation sensors.

FIG. 14 is a diagram showing a specific configuration of an injection lock type pulse laser according to the first to third embodiments.

FIG. 15 is a diagram showing a specific configuration of an injection lock type pulse laser according to the first to third embodiments.

FIG. 16 is a block diagram for measuring performance by the injection lock type pulse laser according to the embodiment of the present invention.

FIG. 17 is a diagram showing the relationship between the pulse width of injection light and the spectral purity of output light.

FIG. 18 is a diagram showing a relationship between a pulse width and a pulse energy of injection light.

FIG. 19 is a diagram showing a schematic configuration of a conventional narrow-band excimer laser.

FIG. 20 is a diagram showing an example of an injection lock type pulse laser.

FIG. 21 is a diagram illustrating spectral purity.

FIG. 22 is a diagram illustrating locking efficiency.

FIG. 23 is a timing chart of signals of respective parts in a conventional injection lock type pulse laser.

FIG. 24 is a diagram showing a relationship between implantation energy and locking efficiency.

FIG. 25 is a diagram showing a relationship between injection energy and relative laser output.

FIG. 26 is a diagram showing an equivalent circuit of a general capacity transfer type magnetic pulse compression discharge device.

27 is a diagram illustrating an example of waveforms of a voltage and a current in each section of the circuit in FIG. 26;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Narrow band fundamental wave laser 2 ... Rear mirror 3 ... Wavelength selection element 4 ... Amplification medium 5 ... Front mirror 6 ... Wavelength conversion part 7, 8 ... Total reflection mirror 10 ... Oscillator stage 20 ... Amplification stage 21 ... Chamber 22 ... Concave mirror 23 ... Convex mirror 24 ... Discharge electrode 30 ... Exposure device 31 ... Exposure device controller 32 ...
Wafer table 40 ... Energy monitor 41 ... Laser controller 42 ... Amplification stage delay processing unit 43 ... Oscillator stage delay processing unit 44 ... Oscillator stage power supply 45 ... Amplification stage power supply 46 ... Switch 47 ... Sensor 48,48a, 48b ... Magnetic switch operation sensor Reference numeral 51: amplification stage delay unit 52: reference delay time setting unit 53, 61: delay time calculation unit 62: oscillator stage delay unit TR: oscillation pulse synchronization signal V0: voltage command value TO: oscillator stage trigger signal TRL: amplification stage trigger τ , Τ1, τ2: delay time Tds: amplification stage reference delay time Tos: oscillator stage delay time Tre: actual delay time

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01S 3/225 H01S 3/223 EF term (Reference) 2H097 AA03 BB02 CA13 CA17 LA10 5F046 BA03 CA04 DA01 DB01 DC01 5F071 AA06 GG02 GG03 GG05 GG07 HH05 HH07 JJ03 JJ05

Claims (4)

[Claims] 1. An oscillator stage for oscillating a narrowed first pulse laser beam at a first timing, and a discharge excitation at a second timing using a magnetic pulse compression circuit to produce the first pulse laser beam. Having an amplification stage for outputting a second pulse laser beam amplified by stimulated emission of the first pulse as injection light, and synchronization control means for appropriately synchronizing and adjusting the first timing and the second timing. In the lock-type narrow-band pulse laser device, the synchronization control unit may perform a process from an oscillation instruction transmitted from a processing device that performs a predetermined processing process using the second pulse laser light to the second timing. Delay time setting means for setting a fixed delay time corresponding to the first timing; and a magnetic pulse compression circuit based on parameters related to laser output. Delay time calculating means for predicting and calculating an actual delay time from the start of energy transfer to the second timing, and calculating a delay time obtained by subtracting the actual delay time from the fixed delay time; and calculating the delay time from the oscillation instruction. And an energy transfer start means for starting the energy transfer of the magnetic pulse compression circuit after the elapse of the delay time calculated by the means. 2. An oscillator stage for oscillating a narrowed first pulse laser beam at a first timing, and discharge excitation at a second timing by using a magnetic pulse compression circuit to produce the first pulse laser beam. Having an amplification stage for outputting a second pulse laser beam amplified by stimulated emission of the first pulse as injection light, and synchronization control means for appropriately synchronizing and adjusting the first timing and the second timing. In the lock-type narrow band pulse laser device, the synchronization control means includes: a magnetic switch operation sensor that detects an ON time of a magnetic switch used on the magnetic pulse compression circuit; and the magnetic pulse based on a parameter related to a laser output. The actual delay time from the start of energy transfer of the compression circuit to the second timing is predicted and calculated. Delay time calculating means for calculating a delay time for delaying oscillation of the oscillator stage in order to generate a first timing corresponding to the clock, and after a time obtained by adding the delay time calculated by the delay time calculating means, An injection-lock type narrow-band pulse laser device comprising: an oscillator stage oscillation delay means for performing oscillation. 3. An oscillator stage for oscillating the narrowed first pulsed laser light at a first timing, and discharge excitation at a second timing using a magnetic pulse compression circuit to produce the first pulsed laser light. Having an amplification stage for outputting a second pulse laser beam amplified by stimulated emission of the first pulse as injection light, and synchronization control means for appropriately synchronizing and adjusting the first timing and the second timing. In the lock-type narrow-band pulse laser device, the synchronization control unit may perform a process from an oscillation instruction sent from a processing device that performs a predetermined processing process using the second pulse laser light to the second timing. Delay time setting means for setting a fixed delay time in accordance with the first timing; and detecting when a magnetic switch used on the magnetic pulse compression circuit is on. A magnetic switch operation sensor, and a real delay time from the start of energy transfer of the magnetic pulse compression circuit to the second timing is calculated based on parameters related to laser output, and the real delay time is calculated from the fixed delay time. A first delay time calculating means for calculating a subtracted first delay time; and an energy transfer of the magnetic pulse compression circuit after a lapse of the first delay time calculated by the first delay time calculating means from the oscillation instruction. Means for starting energy transfer to be started, and a predictive calculation of an actual delay time from the start of energy transfer of the magnetic pulse compression circuit to the second timing based on a parameter related to laser output, and a second timing based on the predictive calculation. A second delay time for delaying the oscillation of the oscillator stage to generate a first timing corresponding to A second delay time calculating means for outputting the second delay time, and an oscillator stage oscillation delay means for causing the oscillator stage to oscillate after adding the second delay time calculated by the second delay time calculating means. An injection-lock type narrow-band pulse laser device characterized by the following. 4. The apparatus according to claim 1, further comprising a temperature sensor for detecting a temperature of the magnetic pulse compression circuit, wherein the temperature detected by the temperature sensor is used as a parameter related to the laser output.
4. The injection-lock type narrow-band pulse laser device according to any one of Items 1 to 3.