Laser device and method for manufacturing electronic device

Abstract

This laser device is provided with: a semiconductor laser that emits continuous light; a first amplifier that amplifies the continuous light and converts the continuous light into pulsed light in synchronization with a light emission trigger signal received from an external device; an optical phase modulator provided on an optical path of the continuous light between the semiconductor laser and the first amplifier; a modulation signal generator that outputs a modulation signal supplied to the optical phase modulator; and a processor for controlling the modulation signal generator, the processor causing the modulation signal generator to generate a modulation signal of the same pattern synchronized with the light emission trigger signal, and modulating the wavelength of the continuous light within a time corresponding to one pulse of the pulsed light by supplying the modulation signal of the same pattern to the optical phase modulator. And adjusting the spectral line width of the pulsed light.

Description

Technical Field

[0001] The present disclosure relates to a laser device and a method for manufacturing an electronic device. Background Art

[0002] In recent years, in semiconductor exposure devices, as semiconductor integrated circuits become smaller and more highly integrated, there is a demand for improved resolution. Therefore, the wavelength of light emitted from the exposure light source is being shortened. For example, as a gas laser device for exposure, a KrF excimer laser device that outputs a laser with a wavelength of about 248nm and an ArF excimer laser device that outputs a laser with a wavelength of about 193nm are used.

[0003] The spectral line width of the natural oscillation light of the KrF excimer laser device and the ArF excimer laser device is as wide as 350pm to 400pm. Therefore, if the projection lens is made of a material that transmits ultraviolet rays such as KrF and ArF lasers, chromatic aberration may sometimes occur. As a result, the resolution may be reduced. Therefore, it is necessary to narrow the spectral line width of the laser output from the gas laser device to a level where the chromatic aberration can be ignored. Therefore, in order to narrow the spectral line width, a narrowing module (Line Narrowing Module: LNM) including narrowing elements (etalon, grating, etc.) is sometimes provided in the laser resonator of the gas laser device. Hereinafter, a gas laser device with a narrowed spectral line width is referred to as a narrowed gas laser device.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: U.S. Patent No. 5760408

[0007] Patent Document 2: U.S. Patent Application Publication No. 2021 / 0226411 Summary of the invention

[0008] A laser device according to one aspect of the present disclosure comprises: a semiconductor laser that emits continuous light; a first amplifier that amplifies the continuous light and converts the continuous light into pulsed light in synchronization with a light emission trigger signal received from an external device; an optical phase modulator that is arranged on an optical path of the continuous light between the semiconductor laser and the first amplifier; a modulation signal generator that outputs a modulation signal that is provided to the optical phase modulator; and a processor that controls the modulation signal generator, wherein the processor causes the modulation signal generator to generate a modulation signal of the same mode that is synchronized with the light emission trigger signal, and by providing the modulation signal of the same mode to the optical phase modulator, the wavelength of the continuous light is modulated within a time equivalent to one pulse of the pulsed light, thereby adjusting the spectral line width of the pulsed light.

[0009] Another aspect of the present invention discloses a method for manufacturing an electronic device, comprising the following steps: generating a laser with an ultraviolet wavelength by a laser device; outputting the laser to an exposure device; and exposing the laser on a photosensitive substrate in the exposure device to manufacture the electronic device, wherein the laser device comprises: a semiconductor laser that emits continuous light; a first amplifier that amplifies the continuous light and converts the continuous light into pulsed light in synchronization with a light emission trigger signal received from an external device; an optical phase modulator that is arranged on an optical path of the continuous light between the semiconductor laser and the first amplifier; a modulation signal generator that outputs a modulation signal provided to the optical phase modulator; a processor that controls the modulation signal generator; and a wavelength conversion system that converts the wavelength of a first pulsed laser output from the first amplifier and outputs a second pulsed laser, wherein the processor causes the modulation signal generator to generate a modulation signal of the same mode that is synchronized with the light emission trigger signal, and by providing the modulation signal of the same mode to the optical phase modulator, the wavelength of the continuous light is modulated within a time equivalent to one pulse of the pulsed light, thereby adjusting the spectral line width of the pulsed light.

[0010] A laser device according to another aspect of the present disclosure comprises: a semiconductor laser that emits continuous light; a first amplifier that amplifies the continuous light and converts the continuous light into pulsed light in synchronization with a light emission trigger signal received from an external device; an optical phase modulator that is arranged on an optical path of the continuous light between the semiconductor laser and the first amplifier; a modulation signal generator that outputs a modulation signal that is provided to the optical phase modulator; and a processor that controls the modulation signal generator, wherein the processor causes the modulation signal generator to generate a modulation signal of the same mode that is synchronized with the light emission trigger signal, and by providing the modulation signal of the same mode to the optical phase modulator, the wavelength of the continuous light is modulated within a time equivalent to one pulse of the pulsed light, and the spectral line width of the pulsed light is adjusted by adjusting the power of the modulation signal.

[0011] Another aspect of the present invention provides a method for manufacturing an electronic device, including the following steps: generating a laser with an ultraviolet wavelength using a laser device; outputting the laser to an exposure device; and exposing the laser on a photosensitive substrate in the exposure device to manufacture the electronic device, wherein the laser device comprises: a semiconductor laser that emits continuous light; a first amplifier that amplifies the continuous light and converts the continuous light into pulsed light in sync with a light-emission trigger signal received from an external device; an optical phase modulator that is disposed on an optical path of the continuous light between the semiconductor laser and the first amplifier; a modulation signal generator that outputs a modulation signal that is provided to the optical phase modulator; and a processor that controls the modulation signal generator, wherein the processor causes the modulation signal generator to generate a modulation signal of the same mode that is synchronized with the light-emission trigger signal, and by providing the modulation signal of the same mode to the optical phase modulator, the wavelength of the continuous light is modulated within a time equivalent to one pulse of the pulsed light, and the spectral line width of the pulsed light is adjusted by adjusting the power of the modulation signal. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Hereinafter, several embodiments of the present disclosure will be described with reference to the accompanying drawings, merely as examples.

[0013] Figure 1 The structure of a laser device according to a comparative example is schematically shown.

[0014] Figure 2 : is a graph showing an example of a white noise spectrum waveform in which the timings of the 11th pulse and the 14th pulse among a plurality of pulses overlap, and a white noise spectrum waveform averaged over 20 pulses.

[0015] Figure 3 This is a graph showing examples of the spectral waveform of each of the first pulse to the fifth pulse and the spectral waveform of the average of 26 pulses.

[0016] Figure 4 The structure of the laser device according to the first embodiment is schematically shown.

[0017] Figure 5 : is a flowchart showing Example 1 of controlling the spectral line width.

[0018] Figure 6 An example of a pseudo-random signal generator using a shift register is shown.

[0019] Figure 7 yes Figure 6 The truth table of the pseudo-random signal generator is shown.

[0020] Figure 8 This is an example of a timing diagram in the solid-state seed device of embodiment 1.

[0021] Fig. 9 The structure of the laser device according to the second embodiment is schematically shown.

[0022] Fig.10 This is an example of a timing diagram in the solid-state seed device of embodiment 2.

[0023] Fig.11 : is a graph showing an example of a spectrum shape when a sine wave with a frequency of fm is applied to an optical phase modulator for modulation.

[0024] Fig.12 is a graph showing the relationship between the frequency sweep width and the spectral line width.

[0025] Fig.13 2 is a flowchart showing a second control example of the spectral line width.

[0026] Fig.14 The structure of the solid seed device according to Modification 1 is schematically shown.

[0027] Fig.15 The structure of the solid seed device according to Modification Example 2 is schematically shown.

[0028] Fig.16 The structure of the exposure device is schematically shown.

[0029] Fig.17 This is a flowchart showing an example of controlling the spectral line width in the third embodiment.

[0030] Fig.18 is a graph showing the relationship between the square root of the power of the modulation signal and the spectral line width.

[0031] Fig.19 An example of a pseudo-random signal generator applied to the laser device of Embodiment 4 is shown.

[0032] Fig. 20 This is a flowchart showing an example of controlling the spectral line width in the fourth embodiment.

[0033] Fig.21 This is a flowchart showing an example of controlling the spectral line width in the fifth embodiment.

[0034] Fig. 22 An example of an optical phase modulator is schematically shown. DETAILED DESCRIPTION

[0035] - Table of Contents - 1. Overview of Laser Device of Comparative Example

[0036] 1.1 Structure

[0037] 1.2 Action

[0038] 1.3 Topics

[0039] 2. Implementation Method 1

[0040] 2.1 Structure

[0041] 2.2 Actions

[0042] 2.3 Specific example of pseudo-random signal generator 2.4 Example of timing diagram

[0043] 2.5 Action and Effect

[0044] 3. Implementation Method 2

[0045] 3.1 Structure

[0046] 3.2 Actions

[0047] 3.3 Explanation of changes in the shape of the spectrum 3.4 Actions and effects

[0048] 4. Modification 1 of Solid Seeder

[0049] 4.1 Structure

[0050] 4.2 Actions

[0051] 5. Modification 2 of Solid Seeder

[0052] 5.1 Structure

[0053] 5.2 Actions

[0054] 6. Other Modifications

[0055] 7. Method for manufacturing electronic device 8. Implementation method 3

[0056] 8.1 Structure

[0057] 8.2 Actions

[0058] 8.3 Action and Effect

[0059] 9. Implementation Method 4

[0060] 9.1 Structure

[0061] 9.2 Actions

[0062] 9.3 Action and Effect

[0063] 10. Implementation Method 5

[0064] 10.1 Structure

[0065] 10.2 Actions

[0066] 10.3 Action and Effect

[0067] 11. Example of optical phase modulator

[0068] 12. Combination of exposure device and laser device

[0069] 13. Others

[0070] Hereinafter, the embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. The embodiments described below represent several examples of the present disclosure and do not limit the content of the present disclosure. In addition, all of the structures and actions described in each embodiment are not necessarily required as the structures and actions of the present disclosure. In addition, the same reference numerals are marked on the same components, and repeated descriptions are omitted.

[0071] 1. Overview of Laser Device of Comparative Example

[0072] 1.1 Structure

[0073] Figure 1The structure of the laser device 10 of the comparative example is schematically shown. The comparative example disclosed in the present invention is a method that the applicant recognizes to be known only by the applicant, and is not a publicly known example recognized by the applicant himself.

[0074] The laser device 10 includes a solid seed device 20 as a master oscillator (Master Oscillator: MO), an excimer amplifier 30 as a power amplifier (Power Amplifier: PA), a monitoring module 40 , an emission aperture 46 , and a laser control processor 50 .

[0075] The solid-state seed generator 20 includes a semiconductor laser system 100 that outputs continuous wave (CW), an optical phase modulator 104 , a solid-state amplifier 106 , a wavelength conversion system 108 , a white noise generator 110 , and a solid-state seed generator control processor 112 .

[0076] The semiconductor laser system 100 includes a distributed feedback (DFB) semiconductor laser that outputs CW laser light at a wavelength of about 773.6 nm. The semiconductor laser system 100 is configured to change the oscillation wavelength by controlling the temperature of the semiconductor laser and / or the current flowing through the semiconductor laser element.

[0077] The optical phase modulator 104 modulates the phase of the CW light output from the semiconductor laser system 100. The white noise generator 110 superimposes a modulation signal on the optical phase modulator 104.

[0078] The solid-state amplifier 106 pulses and amplifies the output light of the optical phase modulator 104. The solid-state amplifier 106 includes a semiconductor optical amplifier (Semiconductor Optical Amplifier: SOA), a titanium sapphire crystal, and a pump pulse laser. By passing a pulse current through the SOA, the SOA pulse-amplifies the CW light output from the optical phase modulator 104 and outputs a pulse laser after pulse amplification. The titanium sapphire crystal is arranged on the optical path of the pulse laser that has been pulse-amplified by the SOA. The pump pulse laser is a laser device that outputs the second harmonic light of the YLF laser. YLF (lithium yttrium fluoride) is a solid-state laser crystal represented by the chemical formula LiYF4. In addition, the solid-state amplifier 106 can also be a structure that includes an optical fiber amplifier instead of an amplifier using a titanium sapphire crystal or in combination with it.

[0079] The wavelength conversion system 108 is a wavelength conversion system including a nonlinear crystal, which performs wavelength conversion on the incident pulsed laser light and performs second harmonic generation twice, and generates pulsed light having an optical frequency four times the optical frequency of the incident pulsed laser light. The wavelength conversion system 108 includes, for example, an LBO crystal and a KBBF crystal. "LBO" is represented by the chemical formula LiB3O5. "KBBF" is represented by the chemical formula KBe2BO3F2. The wavelength conversion system 108 performs wavelength conversion on the pulsed laser light PL1 output from the solid-state amplifier 106, and outputs a pulsed laser light PL2 having a wavelength of about 193.4 nm.

[0080] The solid-state seed device control processor 112 controls the wavelength, power, pulse waveform, spectral line width, etc. of the laser output by the solid-state seed device 20. The solid-state seed device control processor 112 controls the semiconductor laser system 100, the solid-state amplifier 106, the wavelength conversion system 108, and the white noise generator 110 based on the input from the laser control processor 50. In this specification, the processor is a processing device including a storage device storing a control program and a CPU (Central Processing Unit) that executes the control program. The processor is specially configured or programmed to perform various processes included in the present disclosure.

[0081] The excimer amplifier 30 includes a chamber 120, a pulse power module (PPM) 122, a charger 124, a convex mirror 126, and a concave mirror 127. The chamber 120 includes windows 134a, 134b, a pair of electrodes 135a, 135b, and an electrical insulating member 136. ArF laser gas is supplied from a gas supply device (not shown) to the chamber 120. The ArF laser gas contains Ar gas, F2 gas, and Ne gas.

[0082] The PPM 122 includes a switch 123 and a charging capacitor (not shown). The charger 124 holds electric energy for supplying to the PPM 122. The charger 124 is connected to the charging capacitor (not shown). The charger 124 charges the charging capacitor of the PPM 122 according to the instruction from the laser control processor 50.

[0083] The PPM 122 is connected to an electrode 135b in the chamber 120 via a feedthrough in the electrical insulating member 136. The electrode 135a is connected to a ground potential.

[0084] The windows 134 a and 134 b are arranged so that the pulsed laser light amplified by discharge excitation between the electrodes 135 a and 135 b can pass through the windows 134 a and 134 b .

[0085] The convex mirror 126 and the concave mirror 127 are arranged so as to allow the pulse laser PL2 output from the wavelength conversion system 108 to pass through the discharge space between the electrodes 135a and 135b three times to expand the beam.

[0086] The monitoring module 40 includes beam splitters 142 and 143, a spectrum monitor 146, and a light sensor 148. The beam splitter 142 is configured so that the pulse laser PL3 reflected by the beam splitter 142 is incident on the optical path of the pulse laser PL3 output from the excimer amplifier 30 and enters the beam splitter 143. In addition, the beam splitter 142 may also be configured outside the monitoring module 40.

[0087] The beam splitter 143 is configured so that the pulse laser light PL3 ​​reflected by the beam splitter 143 is incident on the spectrum monitor 146 and the pulse laser light PL3 ​​transmitted through the beam splitter 143 is incident on the optical sensor 148 .

[0088] The spectrum monitor 146 monitors the spectrum of the incident pulse laser PL3 and detects the oscillation wavelength of the incident pulse laser PL3. The spectrum monitor 146 may be, for example, an etalon spectrometer. The etalon spectrometer includes a diffusion plate for diffusing the sample light, an etalon, a condenser lens disposed on the emission side of the etalon, and a photodiode array disposed on the focal plane of the condenser lens in order to detect the pattern of interference fringes, and can detect the wavelength by measuring the diameter of the interference fringes.

[0089] The optical sensor 148 detects the pulse energy of the incident pulse laser light PL3. The optical sensor 148 may be, for example, a photodiode or the like.

[0090] The exit aperture 46 is disposed on the optical path of the pulse laser PL3 output from the laser device 10 to the outside, and is configured to switch between outputting the pulse laser PL3 to the outside and shielding the pulse laser PL3. The pulse laser PL3 transmitted through the beam splitter 142 is emitted from the laser device 10 through the exit aperture 46.

[0091] The laser device 10 is connected to the exposure device 80 via a beam transmission unit (BDU) not shown. The BDU is an optical system that transmits the pulse laser PL3 from the laser device 10 to the exposure device 80. The pulse laser PL3 emitted from the laser device 10 enters the exposure device 80.

[0092] The exposure device 80 includes an exposure control processor 86. The exposure control processor 86 controls the exposure device 80. In addition, the exposure control processor 86 is connected to the laser control processor 50. The exposure device 80 is an example of an "external device" in the present disclosure.

[0093] 1.2 Action

[0094] The exposure control processor 86 sends various parameters including a target wavelength, a target line width, and a target pulse energy to the laser control processor 50. In addition, the exposure control processor 86 sends a light emission trigger signal Tr to the laser control processor 50. The laser control processor 50 controls the laser device 10 based on the various parameters and the light emission trigger signal Tr received from the exposure control processor 86. The laser control processor 50 outputs trigger signals Tr1 and Tr2 synchronized with the light emission trigger signal Tr. The trigger signal Tr1 is input to the switch 123 of the PPM 1122, and the trigger signal Tr2 is input to the solid-state amplifier 106.

[0095] The operation of the solid-state seed device 20 is as follows. A CW laser with a wavelength of about 773.6 nm is output from the semiconductor laser system 100. The CW laser is phase-modulated by the optical phase modulator 104, and the shape of the spectrum changes. When a pulse current flows to the SOA in the solid-state amplifier 106 at the timing of the trigger signal Tr2, the CW laser with a changed shape of the spectrum is pulse-amplified, and is further amplified by the solid-state amplifier 106 including an optical fiber amplifier connected downstream of the SOA, and a pulse laser PL1 with a changed shape of the spectrum is output.

[0096] The amplified pulse laser light PL1 is incident on the wavelength conversion system 108 and is wavelength-converted into fourth harmonic light having a wavelength of approximately 193.4 nm.

[0097] The variable range of the wavelength of the pulse laser PL2 output from the solid seed device 20 is the amplification band of the excimer amplifier 30, that is, about 193.2 nm to 193.5 nm.

[0098] The trigger signal Tr1 is input to the switch 123 of the PPM 122 to generate discharge in synchronization with the pulse laser PL2 output from the solid seed device 20 entering the discharge space of the chamber 120 of the excimer amplifier 30. As a result, the pulse laser PL2 output from the solid seed device 20 is amplified by the excimer amplifier 30 in three channels.

[0099] The pulse laser light PL3 ​​amplified by the excimer amplifier 30 is sampled by the beam splitter 142 and the beam splitter 143 of the monitoring module 40 , and the spectrum and the pulse energy are measured by the spectrum monitor 146 and the optical sensor 148 .

[0100] Based on the measured spectrum of the pulsed laser PL3 output from the excimer amplifier 30, the laser control processor 50 sends a control signal of the center wavelength to the solid seed device control processor 112 so that the center wavelength approaches the target wavelength as a target value. The solid seed device control processor 112 sends the instruction values ​​of the temperature value and the current value to the semiconductor laser system 100 based on the control signal obtained from the laser control processor 50. The semiconductor laser system 100 changes the temperature and current of the semiconductor laser of the semiconductor laser system 100 and changes the oscillation wavelength based on the instruction values ​​of the temperature value and the current value obtained from the solid seed device control processor 112.

[0101] In addition, based on the measured spectrum of the pulsed laser PL3 output from the excimer amplifier 30, the laser control processor 50 sends a control signal of the spectral line width to the solid seed device control processor 112 so that the spectral line width approaches the target spectral line width as a target value. The solid seed device control processor 112 changes the signal bandwidth and power of the modulation signal output from the white noise generator 110 based on the control signal obtained from the laser control processor 50.

[0102] The optical phase modulator 104 changes the spectrum of the laser light output from the optical phase modulator 104 according to the signal bandwidth and power of the output from the white noise generator 110 .

[0103] Then, the laser control processor 50 changes the charging voltage of the charger 124 so that the measured pulse energy of the pulse laser light PL3 ​​output from the excimer amplifier 30 approaches the target pulse energy which is the target value.

[0104] 1.3 Topics

[0105] The spectrum of a semiconductor laser is very narrow. Even if the wavelength is converted to deep ultraviolet (DUV) light while keeping the original wavelength, the spectral line width required by the exposure device 80 cannot be obtained. When the output light of the semiconductor laser is phase modulated, a frequency band (spectral rise) caused by the modulation is generated around the original spectrum. If white noise is selected for the modulation signal, the spectrum after phase modulation may become a Gaussian-shaped spectrum corresponding to the signal bandwidth and signal intensity of the white noise. By appropriately selecting the signal bandwidth and signal intensity of the white noise, the spectral line width can be made the target width.

[0106] However, in the case of pulsed light, it is known that the spectrum distribution of the signal superimposed on the optical phase modulator 104 in the white noise generator 110 in an extremely short time equivalent to the pulse width (e.g., about 30 nanoseconds) is not an ideal Gaussian distribution, but has a complex shape with multiple peaks, or the shape varies for each pulse (see Figure 2). Therefore, the spectrum that is pulsed after phase modulation also becomes a complex shape, and the spectral shape of each pulse also changes (refer to Figure 3 ). Therefore, there is a problem that the spectral line width of each pulse is unstable.

[0107] Figure 2 : is a graph showing an example of a white noise spectrum waveform in which the timing of the 11th pulse and the 14th pulse overlap each other among a plurality of pulses and an example of an average white noise spectrum waveform of 20 pulses. Figure 2 As shown, the white noise spectrum waveform is close to a Gaussian shape when averaged, but has a complex shape individually and changes greatly for each pulse.

[0108] Figure 3 : is a graph showing an example of the spectrum waveform of each pulse from the 1st pulse to the 5th pulse and the average spectrum waveform of 26 pulses. Figure 3 As shown, the spectral waveform after phase modulation has a complex shape, and the spectral shape changes with each pulse.

[0109] 2. Implementation Method 1

[0110] 2.1 Structure

[0111] Figure 4 The structure of the laser device 11 according to the first embodiment is schematically shown. Figure 4 The structure shown in the figure shows Figure 1 The difference.

[0112] The laser device 11 includes a solid seed device 21 to replace Figure 1 The solid-state seed device 20 includes a pseudo-random signal generator 111 to replace the white noise generator 110. The pseudo-random signal generator 111 overlaps the modulation signal of the optical phase modulator 104. The pseudo-random signal generator 111 is composed of, for example, a multi-stage shift register and a digital filter. Other structures can be similar to Figure 1 same.

[0113] The pseudo-random signal generator 111 is an example of a "modulation signal generator" in the present disclosure. The solid-state amplifier 106 is an example of a "first amplifier" in the present disclosure, and the pulsed laser PL1 output from the solid-state amplifier 106 is an example of a "first pulsed laser" in the present disclosure. The pulsed laser PL2 output from the wavelength conversion system 108 is an example of a "second pulsed laser" in the present disclosure. The wavelength in the range of about 193.2nm to 193.5nm is an example of an "ultraviolet wavelength" in the present disclosure. The excimer amplifier 30 is an example of a "second amplifier" in the present disclosure.

[0114] 2.2 Action

[0115] CW laser light with a wavelength of about 773.6 nm is output from the semiconductor laser of the solid state seed generator 21. The solid state seed generator control processor 112 sends a reset signal for the shift register in the pseudo random signal generator 111 and a timing signal identical to the trigger signal Tr2 to the pseudo random signal generator 111.

[0116] The pseudo-random signal generator 111 receives a reset signal for the shift register from the solid-state seed device control processor 112, and generates a pseudo-random signal having the same pattern in synchronization with the trigger signal Tr2 according to the timing signal of the trigger signal Tr2. The pseudo-random signal is subjected to a subsequent variable band filter to remove unnecessary spectral components of high-frequency components.

[0117] The optical phase modulator 104 changes the shape of the spectrum by phase-modulating the CW laser light using the pseudo-random signal limited to an appropriate frequency band from the pseudo-random signal generator 111 .

[0118] If the cutoff frequency of the variable band filter is changed toward the high frequency side, the spectral line width of the light becomes wider, and if it is changed toward the low frequency side, it becomes narrower. In addition, by changing the timing of inputting the reset signal to the shift register in the pseudo-random signal generator 111, the waveform and spectral shape of the pseudo-random signal are also changed, and the spectrum of the laser light output from the optical phase modulator 104 is also changed.

[0119] When the spectral line width is controlled, the frequency of the pseudo-random signal is adjusted based on the measured spectral line width. Specifically, the cutoff frequency of the variable-band filter is adjusted.

[0120] Figure 5 1 is a flowchart showing an example of controlling the spectral line width. In step S11, the laser control processor 50 measures the spectral line width of the pulse laser PL3 using the spectrum monitor 146 of the monitoring module 40. The spectrum monitor 146 is an example of a "measurement device" in the present disclosure.

[0121] In step S12, the laser control processor 50 determines whether the measured spectral line width is within the target range.

[0122] If the result of determination in step S12 is "Yes", the laser control processor 50 returns to step S11. If the result of determination in step S12 is "No", the laser control processor 50 moves to step S13.

[0123] In step S13, the laser control processor 50 sends an instruction to the solid-state seed device control processor 112, and the solid-state seed device control processor 112 adjusts the frequency of the pseudo-random signal controlling the optical phase modulator 104. After step S13, the laser control processor 50 returns to step S11.

[0124] Other actions can be combined with Figure 1 The operation of the laser device 10 of the comparative example described in is the same as that of the laser device 10 of the comparative example described in . The laser control processor 50 and the solid seed device control processor 112 are examples of the "processor" in the present disclosure.

[0125] 2.3 Specific example of pseudo-random signal generator

[0126] Figure 6 An example of the pseudo random signal generator 111 using the shift register 160 is shown. Here, as an example of the shift register 160, a simple pseudo random signal generator 111 using four D flip-flops FF1 to FF4 is shown.

[0127] The pseudo-random signal generator 111 includes D flip-flops FF1-FF4, an exclusive OR (XOR) circuit 162, a variable band filter 164, and an amplifier 166. Figure 6 As shown, the structure is that four D flip-flops FF1 to FF4 are connected in series, and the Q2 output of the third-stage D flip-flop FF3 and the Q3 output of the fourth-stage D flip-flop FF4 become inputs to the XOR circuit 162, and the output of the XOR circuit 162 is fed back to the first-stage D flip-flop FF1. The Q3 output of the fourth-stage D flip-flop FF4 is input to the variable-band filter 164, and the output from the variable-band filter 164 is amplified and output by the amplifier 166. The passband of the variable-band filter 164 is controlled by a control signal from the solid-state seed generator control processor 112.

[0128] Figure 7 yes Figure 6 The truth table of the pseudo-random signal generator 111 is shown in FIG. As shown in the figure, the pseudo-random signal generator 111 repeats the same random pattern (pseudo-random pattern) every time the clock is counted 16 times (15 cycles). The digital output of Q3 is band-limited by a filter. The arrangement of "0" or "1" of Q3 becomes a random pattern of binary code.

[0129] Figure 6 and Figure 7 The example shown is a pseudo-random pattern with a period of 15, but by increasing the number of D flip-flops or XOR circuits, with feedback from the appropriate positions, the length of the pattern can be increased to 2. n -1. Here, n is equal to the number of D flip-flops.

[0130] By increasing the frequency of the clock, it is possible to generate a pseudo-random signal having a higher frequency band.

[0131] 2.4 Timing Diagram Example

[0132] Figure 8This is an example of a timing chart in the solid seed device 21 of the first embodiment. Figure 8 The top level F8A indicates the state of the trigger signal Tr2. Figure 8 F8B, which is the second stage from the top of , represents the waveform of the pseudo-random signal after passing through the variable-band filter 164. Figure 8 F8C of the third stage from the top represents the timing of the SOA injection current. Figure 8 The lowest level F8D represents the output waveform of SOA.

[0133] Figure 8 The time Ta in the above is the time when the pulse is amplified by the increase of the current injection of the SOA. This time Ta can be equivalent to the time of one pulse. The first delay time (delay1) relative to the trigger signal Tr2 is adjusted so as to match the timing when the light modulated by the pseudo-random signal that becomes the target time waveform is amplified by the increase of the injection current of the SOA.

[0134] After the second delay time (delay2) from the timing of the trigger signal Tr2, a pulse current (injection current) flows into the SOA. Delay2 is the sum of the time from when the phase-modulated laser light reaches the SOA and when the SOA starts amplification and the time of delay1.

[0135] After a third delay time (delay3) from the timing when the injection current of the SOA starts to increase, the pulse light is output from the SOA. Delay3 is the time during which the continuous light incident on the SOA is pulsed in the SOA and propagates in the SOA and is delayed.

[0136] like Figure 8 As shown, the pseudo random signal generated within a predetermined period (roughly a period of time Ta) after the timing of the trigger signal Tr2 by delay1 has a waveform of the same pattern every time.

[0137] 2.5 Action and Effect

[0138] According to Embodiment 1, since a pseudo-random signal of the same pattern is generated synchronously with the trigger signal Tr2, and superimposed on the optical phase modulator 104, wherein the trigger signal Tr2 is synchronized with the generation timing of the pulse light, a modulation signal having the same waveform for each pulse is superimposed on the optical phase modulator 104, and the spectral shape of the superimposed signal also becomes the same for each pulse. Therefore, the spectrum of the laser light output from the optical phase modulator 104 is modulated to be the same for each pulse, so the spectral shape becomes the same for each pulse, and the spectral line width also becomes the same for each pulse, and becomes stable.

[0139] 2.6 Others

[0140] exist Figure 4In the example shown, a part of the pulsed laser PL3 output from the excimer amplifier 30 is sampled and the spectral line width is measured by the spectrum monitor 146, but it is sufficient to measure the spectral line width of the pulsed laser after pulse amplification by the solid-state amplifier 106. For example, a beam splitter may be arranged on the optical path between the solid-state amplifier 106 and the wavelength conversion system 108, and a part of the pulsed laser PL1 output from the solid-state amplifier 106 may be sampled and guided to a measuring device such as a spectrum monitor, so as to measure the spectral line width of the pulsed laser PL1.

[0141] In addition, for example, a beam splitter may be arranged on the optical path between the wavelength conversion system 108 and the excimer amplifier 30 to sample a portion of the pulsed laser PL2 output from the wavelength conversion system 108 and guide it to a measuring device such as a spectrum monitor to measure the spectral line width of the pulsed laser PL2.

[0142] That is, the pulse lasers PL1 , PL2 , and PL3 propagating on the downstream side of the solid-state amplifier 106 are examples of “pulse lasers pulse-amplified by the first amplifier” in the present disclosure.

[0143] In addition, in Embodiment 1, the CW light of the semiconductor laser is pulsed into laser light by passing a pulse current through the SOA, but the method of generating pulsed laser light is not limited to this example. For example, the CW light of the semiconductor laser can also be amplified into pulsed laser light by exciting the excitation light of the titanium sapphire crystal of the solid-state amplifier 106 with pulsed light.

[0144] Alternatively, a configuration may be used in which an aperture is used to pulse light instead of an SOA. Examples of the aperture include an aperture that combines an EO (Electro Optical) Pockels cell and a polarizer, or a Mach-Zehnder optical modulator that uses the EO effect.

[0145] 3. Implementation Method 2

[0146] 3.1 Structure

[0147] Fig. 9 The structure of the laser device 12 according to the second embodiment is schematically shown. Fig. 9 The structure shown in the figure shows Figure 1 The difference. Fig. 9 The laser device 12 shown includes a solid-state seeder 22 in place of Figure 1The solid-state seed device 20. The solid-state seed device 22 includes a scanning frequency generator 180 instead of the white noise generator 110. The scanning frequency generator 180 superimposes a modulation signal on the optical phase modulator 104. The scanning frequency generator 180 is, for example, composed of a voltage-controlled oscillator (VCO) whose oscillation frequency changes according to an applied voltage. The scanning frequency generator 180 is an example of a "modulation signal generator" in the present disclosure.

[0148] In addition, the solid-state seed device 22 is provided with an optical bandpass filter (BPF) 182 in the optical path between the optical phase modulator 104 and the solid-state amplifier 106. Figure 1 same.

[0149] 3.2 Action

[0150] A CW laser with a wavelength of about 773.6 nm is output from the semiconductor laser of the solid-state seed device 22. The solid-state seed device control processor 112 sends the trigger signal Tr2 to the scanning frequency generator 180. After setting the delay time of delay1 for the timing of the trigger signal Tr2, the scanning frequency generator 180 changes the frequency at a substantially fixed scanning speed (frequency change per unit time) within the desired time to scan the frequency and output a frequency scanning signal.

[0151] The optical phase modulator 104 modulates the phase of the CW laser light using the frequency sweep signal provided from the sweep frequency generator 180 to change the shape of the spectrum.

[0152] Fig.10 This is an example of a timing diagram in the solid seed device 22 of the second embodiment. Fig.10 , the respective graphs of the trigger signal Tr2, the frequency shift of the frequency sweep signal, the frequency sweep signal, the light waveform (CW light) before amplification by the SOA, the SOA injection current, and the SOA output waveform are shown from top to bottom.

[0153] In addition, the frequency shift graph of the frequency sweep signal shown in the second level from the top shows an example in which the vertical axis is frequency, the basic frequency is fm, and the sweep width is Δf. That is, the frequency of the frequency sweep signal can change from fm to fm+Δf. In addition, the sweep width Δf satisfies Δf<fm. Fig.10 , an example of sweeping the frequency in the positive direction is shown, but the frequency can also be swept in the negative direction.

[0154] The frequency shift of the frequency sweep signal starts after the timing of the trigger signal Tr2 is delayed by the delay time of delay1, and the frequency changes at a fixed ratio during the time Tb. Delay1 is adjusted so that the light modulated by the frequency sweep signal of the time Tb is pulsed by the SOA in the solid-state amplifier 106. The time Tb is Figure 8 The time Ta described in is equal to or greater than the time Ta, and is preferably approximately the same as the time Ta. Fig.10 The delay2 and delay3 shown are the same as Figure 8 same.

[0155] 3.3 Explanation of the shape change of the spectrum

[0156] Reference Fig.11 , which explains the change in the shape of the spectrum. Fig.11 The optical spectrum shape is shown when a sine wave with a frequency fm is applied to the optical phase modulator 104. At this time, a sideband with a distance fm is generated around the carrier frequency fc (see Figure F11A). Fig.11 In the graph F11A shown above, the spectrum SP0 shown by the dashed line represents a spectrum without modulation (before modulation). In addition, the spectrum SP1 shown by the solid line represents a spectrum when a sine wave with a frequency fm is applied for modulation.

[0157] The solid state seeder control processor 112 changes the spectral line width by sweeping the modulation frequency fm (see Figure F11B). Fig.11 In the graph F11B shown in the lower stage of , the case where scanning is performed from the spectrum SP2 shown by the dotted line toward the spectrum SP3 shown by the solid line on the high-frequency side is shown, but scanning may be performed toward the low-frequency side.

[0158] The solid seed device 22 uses only the +1st sideband of the frequency fc+fm shown in the graph F11B, and the other spectral components (in Fig.11 In the example of the optical phase modulator 104, the optical bandpass filter 182 is cut off. In this way, in order to cut off unnecessary spectral components, in the solid-state seed device 22, an optical bandpass filter 182 is configured at the post-stage of the output of the optical phase modulator 104. In the diagram F11B, an example of the transmission characteristics of the optical bandpass filter 182 is shown by a double-dashed line. In this way, only the spectral components of the light selected by the optical bandpass filter 182, such as the components of fc+fm (+1-order sideband), are input to the solid-state amplifier 106.

[0159] Fig.12 This is a graph showing the relationship between the frequency sweep width and the spectral line width. The spectral line width of light changes in a manner that it becomes wider as the sweep width of the modulation frequency fm increases, and becomes narrower as the sweep width becomes narrower. Fig.12 As shown, the sweep width of the modulation frequency fm is roughly in a linear relationship with the spectral line width.

[0160] In the case of controlling the spectral line width, the sweep width of the modulation frequency fm is adjusted based on the spectral line width measured by the monitoring module to obtain the target spectral line width.

[0161] Fig.13 is a flow chart showing Example 2 of controlling the spectral line width. Fig.13 The flowchart shown in the figure shows Figure 5 The difference. Fig.13 The flowchart shown includes step S14 instead of Figure 5 That is, when the determination result of step S12 is "No", the laser control processor 50 transfers to step S14.

[0162] In step S14, the laser control processor 50 sends an instruction to the solid seed device control processor 112, and the solid seed device control processor 112 adjusts the sweep width of the frequency sweep signal of the optical phase modulator 104. After step S14, the laser control processor 50 returns to step S11. The other steps can be the same as Figure 5 same.

[0163] 3.4 Action and Effect

[0164] According to Embodiment 2, since the waveform of the modulation signal input to the optical phase modulator 104 is synchronized with the trigger signal Tr2, the pulsed laser light is modulated with the same waveform. As a result, each pulse has the same spectral shape and the same spectral line width.

[0165] In order to easily control the line width, such as Fig.12 As shown, the linearity of the relationship between the sweep width of the modulation frequency fm and the spectral line width is good. By sweeping the frequency at a fixed sweep speed, a spectrum waveform close to a rectangle is obtained. In addition, by changing the sweep speed, spectra of various shapes can be obtained.

[0166] 4. Modification 1 of Solid Seeder

[0167] 4.1 Structure

[0168] right Figure 4 A modified example of the solid seed device 21 described in is described. Fig.14 The structure of the solid seed device 23 of the modification example 1 is schematically shown. Figure 4 Solid seed device 21 and application Fig.14 The solid-state seed device 23 shown. The solid-state seed device 23 can also be a structure having two seed lights input to the wavelength conversion system 240.

[0169] The solid-state seed generator 23 includes a first solid-state laser device 200 , a second solid-state laser device 210 , a dichroic mirror 230 , a wavelength conversion system 240 , a solid-state seed generator control processor 112 , and a pseudo-random signal generator 111 .

[0170] The solid-state seed device 23 has the following system structure: in the wavelength conversion system 240, the pulse laser PL4 with a wavelength of about 1554nm output from the first solid-state laser device 200 and the pulse laser PL5 with a wavelength of about 257.6nm output from the second solid-state laser device 210 are converted into a pulse laser PL2 with a wavelength of about 193.4nm by performing secondary frequency summing.

[0171] The first solid-state laser device 200 includes a semiconductor laser system 204 and a solid-state amplifier 206. The semiconductor laser system 204 can be used in conjunction with Figure 4 The semiconductor laser system 204 has the same structure as the semiconductor laser system 100 shown, but has an oscillation wavelength different from that of the semiconductor laser system 100. The semiconductor laser system 204 includes a semiconductor laser that performs CW oscillation in a single longitudinal mode at a wavelength of approximately 1554 nm.

[0172] The solid-state amplifier 206 may be an optical parametric amplifier (OPA), such as PPLN (periodically poled lithium niobate) or PPKTP (periodically poled KTP).

[0173] The solid-state amplifier 206 is configured to amplify the pulses of seed light by inputting a 1030 nm pulse laser light described later as pump light and a laser light output from the semiconductor laser system 204 as seed light.

[0174] The second solid-state laser device 210 includes a semiconductor laser system 212, an optical phase modulator 104, a solid-state amplifier 216, two nonlinear crystals, namely, an LBO crystal 220 and a CLBO crystal 222, and a dichroic mirror 224. The LBO crystal 220 and the CLBO crystal 222 generate second harmonics twice and convert the wavelength to quadruple the optical frequency. "CLBO" is composed of the chemical formula CsLiB6O 10 express.

[0175] Semiconductor laser system 212 can be used with Figure 2 The semiconductor laser system 212 has the same structure as the semiconductor laser system 100 shown, but has an oscillation wavelength different from that of the semiconductor laser system 100. The semiconductor laser system 212 includes a semiconductor laser that performs CW oscillation in a single longitudinal mode at a wavelength of about 1030 nm.

[0176] The solid-state amplifier 216 may be a structure including a Yb fiber amplifier and a Yb:YAG crystal, for example. The solid-state amplifier 216 may also be a structure similar to the solid-state amplifier 106. The optical phase modulator 104 is arranged on the optical path between the semiconductor laser system 212 and the solid-state amplifier 216. The solid-state amplifier 216 is an example of a "first amplifier" in the present disclosure.

[0177] The dichroic mirror 224 is arranged on the optical path between the LBO crystal 220 and the CLBO crystal 222, so that the pulsed laser with a wavelength of about 515 nm is transmitted with high transmittance, and the pulsed laser with a wavelength of about 1030 nm is reflected with high reflectivity. The dichroic mirror 224 is arranged so that the pulsed laser with a wavelength of about 1030 nm reflected with high reflectivity is incident as the pump light of the solid-state amplifier 206. Instead of the dichroic mirror 224, a beam splitter (not shown) may be arranged between the LBO crystal 220 and the solid-state amplifier 216, so that the pulsed laser emitted from the solid-state amplifier 216 is branched to be incident on the LBO crystal 220 and the solid-state amplifier 206 respectively.

[0178] The wavelength conversion system 240 includes CLBO crystals 242 and 243 and rotating stages 252 and 253. The CLBO crystals 242 and 243 are respectively arranged on rotating stages 252 and 253 including piezoelectric elements, and are configured to be able to change the incident angle of each crystal at high speed.

[0179] The color dichroic mirror 230 is a structure that reflects the pulse laser PL4 with a wavelength of about 1554nm output from the first solid-state laser device 200 with high reflectivity, and allows the pulse laser PL5 with a wavelength of about 257.6nm output from the second solid-state laser device 210 to pass through with high transmittance, and is configured to allow the two pulse lasers to coaxially enter the wavelength conversion system 240.

[0180] 4.2 Action

[0181] In the solid seed device 23, by setting the wavelength of the pulsed laser PL5 output from the second solid-state laser device 210 to be fixed and changing the wavelength of the pulsed laser PL4 output from the first solid-state laser device 200 according to each pulse, the wavelength of the pulsed laser PL2 output from the wavelength conversion system 240 can be changed.

[0182] The second solid-state laser device 210 operates as follows. The solid-state laser device control processor 112 fixes the oscillation wavelength of the second solid-state laser device 210 to 1030 nm. That is, the solid-state laser device control processor 112 fixes the current value of the semiconductor laser in the semiconductor laser system 212, causes the semiconductor laser to oscillate continuously, and outputs CW laser light from the semiconductor laser.

[0183] The CW laser light outputted from the semiconductor laser system 212 is phase-modulated by the optical phase modulator 104 and then input to the solid-state amplifier 216. The operation of the pseudo-random signal generator 111 and the optical phase modulator 104 is similar to the operation of the solid-state amplifier 216. Figure 4 The described embodiment 1 is the same.

[0184] The solid-state seed generator control processor 112 performs pulse amplification of the CW laser through the solid-state amplifier 216 in synchronization with the trigger signal Tr2. The solid-state amplifier 216 outputs a pulse laser PL6 with a wavelength of 1030 nm.

[0185] The pulsed laser PL6 with a wavelength of 1030 nm output from the solid-state amplifier 216 is converted into a second harmonic light with a wavelength of 515 nm by the LBO crystal 220. The second harmonic light with a wavelength of 515 nm passes through the dichroic mirror 224 with high transmittance and is converted into a pulsed laser PL5 with a wavelength of 257.6 nm by the CLBO crystal 222.

[0186] Here, the dichroic mirror 224 reflects the 1030 nm pulse laser light that cannot be wavelength-converted by the LBO crystal 220 at a high reflectivity, and allows the light to enter the solid-state amplifier 206 of the first solid-state laser device 200 as pump light.

[0187] On the other hand, the laser control processor 50 and the solid-state seed device control processor 112 can change the wavelength of the pulsed laser PL4 output from the first solid-state laser device 200 around 1554 nm by controlling the temperature value and / or current value of the semiconductor laser in the semiconductor laser system 204 of the first solid-state laser device 200. The solid-state seed device control processor 112 can change the oscillation wavelength of the semiconductor laser system 204 for each pulse.

[0188] The CLBO crystal 242 of the wavelength conversion system 240 performs sum frequency mixing on the pulsed laser PL4 with a wavelength of about 1554 nm output from the first solid-state laser device 200 and the pulsed laser PL5 with a wavelength of 257.6 nm output from the CLBO crystal 222, and converts the wavelength into a pulsed laser with a wavelength of about 220.9 nm. Furthermore, the CLBO crystal 243 performs sum frequency mixing on the pulsed laser with a wavelength of about 220.9 nm and the pulsed laser with a wavelength of 1554 nm, and converts the wavelength into a pulsed laser PL2 with a wavelength of about 193.4 nm. Then, the pulsed laser PL2 is output from the wavelength conversion system 240.

[0189] 4.3 Others

[0190] exist Fig.14, an example in which the optical phase modulator 104 is arranged in the second solid-state laser device 210 is described, but the optical phase modulator 104 may also be arranged in the optical path of the CW laser of the semiconductor laser system 204 in the first solid-state laser device 200. That is, the optical phase modulator 104 may also be arranged in the optical path between the semiconductor laser system 204 and the solid-state amplifier 206.

[0191] 5. Modification 2 of Solid Seeder

[0192] 5.1 Structure

[0193] right Fig. 9 A modified example of the solid seed device 22 described in is described. Fig.15 The structure of the solid seed device 24 of the second modification is schematically shown. Fig. 9 Solid seed device 22 is used Fig.15 The solid seed device 24 is shown. Fig.15 The structure shown in the figure shows Fig.14 The solid-state seed device 24 has a scanning frequency generator 180, and an optical bandpass filter 182 is provided on the optical path between the optical phase modulator 104 and the solid-state amplifier 216 to replace Fig.14 The pseudo random signal generator 111 in the other structures can be Fig.14 same.

[0194] 5.2 Action

[0195] Fig.15 The operation of the scanning frequency generator 180, the optical phase modulator 104 and the optical bandpass filter 182 shown in FIG. Fig. 9 The same as implementation mode 2 described in .

[0196] The CW laser light output from the semiconductor laser system 212 is transformed into a desired spectral shape by passing through the optical phase modulator 104 and the optical bandpass filter 182 to which the frequency sweep signal output from the sweep frequency generator 180 is applied, and thus becomes the same spectral shape for each pulse. Figure 4 The same as the implementation mode 1 described in . Fig.15 The solid-state seed generator 24 and the optical phase modulator 104 shown can also be arranged on the optical path of the CW laser of the semiconductor laser system 204 in the first solid-state laser device 200 .

[0197] 6. Other Modifications

[0198] The semiconductor laser used in the semiconductor laser system is not limited to the DFB laser, and may be a distributed bragg reflector (DBR) semiconductor laser or a sampled grating distributed bragg reflector (SG-DBR) semiconductor laser.

[0199] In Embodiments 1 and 2, an example of a three-channel multi-channel amplifier is shown as an excimer amplifier, but the amplifier is not limited to a multi-channel amplifier, and may be an amplifier including an optical resonator such as a Fabry-Perot resonator or a ring resonator, for example.

[0200] In Embodiment 1 and Embodiment 2, an example of a structure combining a solid-state seed device and an ArF excimer amplifier is shown, but it is not limited to this embodiment, and it can also be a combination of an excimer amplifier containing KrF laser gas and a solid-state seed device oscillating in the amplification band of the KrF excimer. As a specific example, the solid-state seed device can also be a semiconductor laser system that outputs a pulsed laser with a wavelength of about 745.2nm, a solid-state amplifier, and a wavelength conversion system that converts the wavelength into a third harmonic light with a wavelength of about 248.4nm. The wavelength conversion element in this case can also be an LBO crystal that converts the wavelength into a second harmonic light and a CLBO crystal that performs sum frequency mixing on the second harmonic light and the fundamental wave.

[0201] 7. About the manufacturing method of electronic devices

[0202] Fig.16 The structure example of the exposure device 80 is schematically shown. The exposure device 80 includes an illumination optical system 806 and a projection optical system 808. The laser device 11 generates laser light and outputs the laser light to the exposure device 80. The illumination optical system 806 illuminates the mask pattern of the mask (not shown) arranged on the mask stage RT using the laser light incident from the laser device 11. The projection optical system 808 performs reduced projection of the laser light transmitted through the mask so as to form an image on the workpiece (not shown) arranged on the workpiece stage WT. The workpiece is a photosensitive substrate such as a semiconductor wafer coated with a photoresist.

[0203] The exposure device 80 exposes the workpiece with a laser reflecting the mask pattern by synchronously moving the mask stage RT and the workpiece stage WT in parallel. After the mask pattern is transferred to the semiconductor wafer through the above exposure process, a semiconductor device can be manufactured through multiple processes. A semiconductor device is an example of an "electronic device" in the present disclosure. The laser device 12 can also be used instead of the laser device 11.

[0204] 8. Implementation Method 3

[0205] 8.1 Structure

[0206] The structure of the laser device of the third embodiment Figure 4 The laser device of the third embodiment is different from the laser device 11 of the first embodiment in the content of the control performed by the laser control processor 50 .

[0207] 8.2 Action

[0208] The operation of the laser device of Embodiment 3 will be described below in terms of differences from the operation of the laser device 11 of Embodiment 1. In the laser device 11 of Embodiment 1, the spectral line width of the pulsed laser PL3 is controlled by adjusting the frequency of a pseudo-random signal, which is used as a modulation signal for controlling the optical phase modulator 104. In contrast, in the laser device of Embodiment 3, the spectral line width of the pulsed laser PL3 is controlled by adjusting the power of a modulation signal of the same mode synchronized with the light emission trigger signal Tr.

[0209] Fig.17 FIG. 4 is a flowchart showing an example of controlling the spectral line width in Embodiment 3. Fig.17 Instead of the flowchart shown Figure 5 The flowchart shown in Fig.17 In step S21, the laser control processor 50 uses the spectrum monitor 146 of the monitoring module 40 to measure the spectral line width of the output of the excimer amplifier 30, that is, the pulse laser PL3.

[0210] In step S22, the laser control processor 50 calculates the difference between the target line width regularly updated by the exposure control processor 86 and the measurement result (measured line width) of step S21.

[0211] In step S23, the laser control processor 50 determines whether the difference calculated in step S22 is within the allowable range. If the determination result in step S23 is "yes", that is, if the difference is within the allowable range, the laser control processor 50 returns to step S21.

[0212] On the other hand, when the result of determination in step S23 is “NO”, that is, when the difference is outside the allowable range, the laser control processor 50 proceeds to step S24 .

[0213] In step S24, the laser control processor 50 determines the power of the modulation signal based on a predetermined function and the difference calculated in step S22, and changes the power of the modulation signal superimposed on the optical phase modulator 104, wherein the function represents the relationship between the square root of the power of the modulation signal and the spectral line width. When the spectral line width measured by the laser control processor 50 in step S21 (the measurement result of step S21) is smaller than the target range, the power of the modulation signal is increased. On the other hand, when the spectral line width measured in step S21 is larger than the target range, the laser control processor 50 reduces the power of the modulation signal. In addition, instead of the predetermined function representing the relationship between the square root of the power of the modulation signal and the spectral line width, pre-recorded table data representing the relationship between the square root of the power of the modulation signal and the spectral line width can be used. The action of step S24 can also be performed by the solid seed device control processor 112 according to the instruction of the laser control processor 50.

[0214] After step S24, the laser control processor 50 returns to step S21. The other operations may be the same as those of the laser device 11 in the first embodiment.

[0215] Fig.18 This is a graph showing the relationship between the square root of the power of the modulation signal and the spectral line width. Fig.18 The black dots shown plot the experimentally obtained measurement results, and the dashed straight line is an approximate straight line derived from these plotted points. Fig.18 As shown, the square root of the power of the modulated signal is approximately linearly related to the spectral line width. By storing the function or table data defining the relationship represented by the dotted line in the memory of the laser control processor 50 or the solid seed device control processor 112, the laser control processor 50 or the solid seed device control processor 112 can perform the processing of step S24.

[0216] 8.3 Action and Effect

[0217] According to the laser device of the third embodiment, the linearity of the relationship between the square root of the power of the modulation signal and the line width of the pulse laser PL3 is high (see Fig.18 ), so the spectral line width can be controlled more easily and with high precision.

[0218] 9. Implementation Method 4

[0219] 9.1 Structure

[0220] Fig.19 3 is a block diagram showing an example of a pseudo-random signal generator 312 applied to a laser device according to Embodiment 4. The laser device according to Embodiment 4 includes Fig.19 The pseudo-random signal generator 312 shown in FIG. Figure 6The pseudo random signal generator 111 is shown. Other structures may be the same as the laser device 11 of the first embodiment.

[0221] A trigger regeneration circuit 314 and an initial value setting circuit 316 are added to the pseudo random signal generator 312, and the initial value of the shift register 360 is adjusted so that the shape of the spectral waveform (spectral shape) of the generated pulse laser light PL3 ​​becomes a single peak.

[0222] The pseudo-random signal generator 312 includes D flip-flops FF1-FF36, at least one XOR circuit 162, a variable band filter 164, and an amplifier 166. Fig.19 As shown, 36 D flip-flops FF1 to FF36 are connected in series, and the Q output of the 11th-stage D flip-flop FF11 and the Q output of the 36th-stage D flip-flop FF36 become inputs to the XOR circuit 162, and the output of the XOR circuit 162 is fed back to the 1st-stage D flip-flop FF1. The Q output of the 36th-stage D flip-flop FF36 is also input to the variable-band filter 164, and the output from the variable-band filter 164 is amplified and output by the amplifier 166. The passband of the variable-band filter 164 and the output power of the amplifier 166 are controlled by the control signal from the solid-state seed generator control processor 112.

[0223] The trigger regeneration circuit 314 generates a timing signal for changing the initial value of the D flip-flops FF1 to FF36 based on the trigger signal Tr2 from the solid-state seed device control processor 112 and the clock of the pseudo-random signal generator 312.

[0224] In the initial value setting circuit 316, in synchronization with the timing signal generated by the trigger regeneration circuit 314, a signal is sent to the SET terminal or the CLR terminal of the D flip-flops FF1 to FF36 according to the control signal from the solid state seed device control processor 112, so that the initial value of the D flip-flops FF1 to FF36 becomes "0" or "1" ("low" or "high"). For example, when the initial value is set to "0", a signal is sent to the CLR terminal, and when the initial value is set to "1", a signal is sent to the SET terminal.

[0225] In addition, Fig.19In the example of using 36-stage D flip-flops, the number of stages of the D flip-flops is not limited to this example. For example, the number of stages, feedback positions, and the number of XORs can be appropriately configured and connected according to a known feedback polynomial. In addition, the shift register 360 composed of multiple stages of the above-mentioned D flip-flops can also be composed of an FPGA (Field Programmable Gate Array) or the like. In addition, the power of the output modulated signal is adjusted by the amplifier 166, but a variable attenuator can be inserted in the rear stage or the front stage of the amplifier 166 to adjust the output power. In addition, an XNOR circuit can be used instead of the XOR circuit 162. The pseudo-random signal generator 312 is an example of a "modulation signal generator" in the present disclosure. The amplifier 166 is an example of a "third amplifier" in the present disclosure.

[0226] 9.2 Action

[0227] Fig. 20 FIG. 4 is a flowchart showing an example of controlling the spectral line width in Embodiment 4. Fig. 20 Instead of the flowchart shown Fig.17 The flowchart shown in Fig. 20 In step S31 , the laser control processor 50 uses the spectrum monitor 146 of the monitoring module 40 to measure the spectrum waveform of the output of the excimer amplifier 30 , that is, the pulsed laser PL3 .

[0228] In step S32, the laser control processor 50 checks whether the measured spectrum shape is unimodal or multimodal, and determines whether the spectrum waveform is unimodal. If the determination result of step S32 is "no", that is, if the spectrum shape is multimodal, the laser control processor 50 transfers to step S33.

[0229] In step S33, the laser control processor 50 changes the initial value of the shift register 360 via the solid state seed device control processor 112, and returns to step S31.

[0230] On the other hand, when the result of determination in step S32 is “Yes”, that is, when the spectrum shape is unimodal, the laser control processor 50 proceeds to step S34 .

[0231] In step S34, the laser control processor 50 measures the spectral line width according to the acquired spectral waveform.

[0232] In step S35, the laser control processor 50 calculates the difference between the target line width regularly updated by the exposure control processor 86 and the measurement result of step S34.

[0233] In step S36, the laser control processor 50 determines whether the calculated difference is within the allowable range. If the result of the determination in step S36 is "yes", that is, if the difference is within the allowable range, the laser control processor 50 returns to step S31.

[0234] On the other hand, if the result of determination in step S36 is "No", that is, if the difference is outside the permissible range, the laser control processor 50 proceeds to step S37. Fig.17 The same as step S24. In addition, in step S37, instead of adjusting the power of the modulation signal, the bandwidth of the modulation signal can be adjusted using the variable band filter 164. After step S37, the laser control processor 50 returns to step S31. Other actions can be the same as the actions of the laser device of embodiment 3.

[0235] 9.3 Action and Effect

[0236] According to the laser device of the fourth embodiment, by adjusting the initial value of the shift register 360, the spectral shape of the single peak can be controlled to be the target spectral line width. Fig.18 As described in , since the linearity of the relationship between the square root of the power of the modulation signal and the spectral line width is high, the spectral line width can be controlled more easily and with high precision.

[0237] In addition, in place of Fig. 20 In step S37 shown in the figure, when the bandwidth of the modulation signal is adjusted, since the linearity of the relationship between the bandwidth of the modulation signal and the spectral line width is high, the spectral line width can be controlled more easily and with high precision.

[0238] 10. Implementation Method 5

[0239] 10.1 Structure

[0240] The structure of the laser device of the fifth embodiment is the same as that of the laser device of the fourth embodiment. The laser device of the fifth embodiment is different from the laser device of the fourth embodiment in the content of the control performed by the laser control processor 50 .

[0241] 10.2 Actions

[0242] Regarding the operation of the laser device of Embodiment 5, the difference from the operation of the laser device of Embodiment 4 is described. The laser device of Embodiment 5 performs coarse adjustment on the spectral line width of the pulsed laser PL3 by changing the bandwidth of the modulation signal superimposed on the optical phase modulator 104, and performs fine adjustment on the spectral line width of the pulsed laser PL3 by changing the power of the modulation signal. Fine adjustment is an adjustment with a smaller adjustment amount than coarse adjustment. For example, the range of the adjustment amount of the spectral line width that can be adjusted by fine adjustment may be less than 0.4 pm, and the range of the adjustment amount of the spectral line width that can be adjusted by coarse adjustment may be greater than 0.4 pm and less than 3 pm.

[0243] The laser control processor 50 of the laser device of Embodiment 5 determines whether to implement coarse adjustment or fine adjustment according to the size of the difference between the target spectral line width and the measured spectral line width. It is also possible to implement fine adjustment when the difference from the target value is outside the allowable range and less than 0.4 pm (hereinafter referred to as the allowable range of fine adjustment), and implement coarse adjustment when the difference from the target value is outside the allowable range and greater than 0.4 pm and less than 3 pm (hereinafter referred to as the allowable range of coarse adjustment).

[0244] Fig.21 FIG. 5 is a flowchart showing an example of controlling the spectral line width in Embodiment 5. Fig.21 Instead of the flowchart shown Fig. 20 The flowchart shown. Fig.21 The flowchart shown in the figure shows Fig. 20 The difference.

[0245] Fig.21 The flowchart shown includes steps S38 to S41 instead of Fig. 20 Steps S36 and S37 are shown.

[0246] After step S35, in step S38, the laser control processor 50 determines whether the difference calculated in step S35 is within the allowable range of coarse adjustment. If the determination result of step S38 is "No", that is, if the difference is outside the allowable range of coarse adjustment, the laser control processor 50 transfers to step S39.

[0247] In step S39, the laser control processor 50 changes the bandwidth of the modulation signal superimposed on the optical phase modulator 104 through the variable band filter 164. Step S39 applies the method of embodiment 1. The action of step S39 can also be performed by the solid-state seed device control processor 112 according to the instruction of the laser control processor 50. After step S39, the laser control processor 50 returns to step S31.

[0248] If the result of determination in step S38 is "yes", that is, if the difference is within the permissible range of coarse adjustment, the laser control processor 50 transfers to step S40. In step S40, the laser control processor 50 determines whether the difference calculated in step S35 is within the permissible range of fine adjustment. If the result of determination in step S40 is "yes", that is, if the difference is within the permissible range of fine adjustment, the laser control processor 50 returns to step S31.

[0249] If the result of determination in step S40 is "No", that is, if the difference is outside the allowable range of fine adjustment, the laser control processor 50 transfers to step S41. Step S41 is Fig.17 After step S41, the laser control processor 50 returns to step S31. Other operations may be the same as those of the laser device of embodiment 4.

[0250] 10.3 Action and Effect

[0251] According to the laser device of the fifth embodiment, the spectral shape of the single peak can be always controlled to the target spectral line width by adjusting the initial value of the shift register 360. In addition, in the laser device of the fifth embodiment, the bandwidth of the modulation signal is changed when the spectral line width is roughly adjusted, and the power of the modulation signal is changed when the spectral line width is finely adjusted. Therefore, compared with the case where the line width is controlled only by the power of the modulation signal, the amount of change of the power of the modulation signal is small, so the overall stability of the modulation signal generator including the pseudo-random signal generator 111 is good, the heat load applied to the optical phase modulator 104 is small, and stable control can be performed.

[0252] Furthermore, compared with the case of performing line width control only by the bandwidth of the modulation signal, the setting resolution can be finer by using the change in the power of the modulation signal.

[0253] 11. Example of optical phase modulator

[0254] Fig. 22 An example of an optical phase modulator 104 is schematically shown. The optical phase modulator 104 is an electro-optical (EO) modulator, and modulates the phase of a laser pulse by applying a voltage signal as a phase modulation signal to an electro-optical element (for example, lithium niobate). Fig. 22 The optical phase modulator 104 shown is configured by placing electrodes 402 a and 402 b on the surface of a lithium niobate crystal 400 via an optical waveguide 404 , and applying a voltage signal between the electrodes 402 a and 402 b .

[0255] An input optical fiber 410 and a lens 412 are arranged on the optical input port side of the optical phase modulator 104, and a lens 414 and an output optical fiber 416 are arranged on the optical output port side. The lens 412 and the lens 414 are arranged to face each other with the lithium niobate crystal 400 interposed therebetween. The laser light guided by the input optical fiber 410 is input to the lithium niobate crystal 400 via the lens 412. The laser light that has passed through the optical waveguide 404 is incident on the output optical fiber 416 via the lens 414, and is guided by the output optical fiber 416 to the solid-state amplifier 106 (see Figure 4 ).

[0256] 12. Combination of exposure device and laser device

[0257] Can also be substituted with Fig.16 The laser device 11 is used together with the exposure device 80 shown in the figure, and the laser device of each of Embodiment 3 to Embodiment 5 is applied to manufacture a semiconductor device.

[0258] 13. Others

[0259] The above description is not limiting but merely illustrative. Therefore, it is obvious to those skilled in the art that the embodiments of the present disclosure can be changed without departing from the claims. In addition, it is obvious to those skilled in the art that the embodiments of the present disclosure can be used in combination.

[0260] Unless otherwise expressly stated, the terms used in this specification and the claims as a whole should be interpreted as "non-limiting" terms. For example, terms such as "including", "having", "having", and "having" should be interpreted as "not excluding the existence of constituent elements other than the recorded constituent elements". In addition, the modifier "1" should be interpreted as "at least 1" or "1 or more". In addition, the term "at least one of A, B and C" should be interpreted as "A", "B", "C", "A+B", "A+C", "B+C" or "A+B+C". Furthermore, it should be interpreted as also including their combination with constituent elements other than "A", "B" and "C".

Claims

1. A laser device, wherein: The laser device comprises: A semiconductor laser that emits continuous light; a first amplifier that amplifies the continuous light and converts the continuous light into pulse light in synchronization with a light emission trigger signal received from an external device; an optical phase modulator disposed on an optical path of the continuous light between the semiconductor laser and the first amplifier; a modulation signal generator, the output of which is provided to the modulation signal of the optical phase modulator; as well as a processor that controls the modulation signal generator, The processor enables the modulation signal generator to generate the modulation signal of the same mode synchronized with the light-emitting trigger signal, and by providing the modulation signal of the same mode to the optical phase modulator, the wavelength of the continuous light is modulated within a time equivalent to one pulse of the pulse light, thereby adjusting the spectral line width of the pulse light.

2. The laser device according to claim 1, wherein: The modulated signal is a pseudo-random signal.

3. The laser device according to claim 2, wherein: The modulation signal generator includes a shift register.

4. The laser device according to claim 3, wherein: The modulation signal generator includes a band-variable filter.

5. The laser device according to claim 4, wherein: The processor controls the passband of the variable band filter to adjust the spectral line width.

6. The laser device according to claim 5, wherein: The processor changes the cutoff frequency of the variable band filter toward the high frequency side when the spectral line width is smaller than the target spectral line width, and changes the cutoff frequency of the variable band filter toward the low frequency side when the spectral line width is larger than the target spectral line width.

7. The laser device according to claim 1, wherein: The modulation signal is a frequency sweep signal.

8. The laser device according to claim 7, wherein: The modulation signal generator includes a scanning frequency generator.

9. The laser device according to claim 8, wherein: The modulation signal generator includes a voltage-controlled oscillator whose oscillation frequency changes according to an applied voltage.

10. The laser device according to claim 8, wherein: The modulation signal generator sweeps the frequency at a fixed sweep speed within the time corresponding to the one pulse.

11. The laser device according to claim 8, wherein: The laser device includes an optical bandpass filter on the optical path between the optical phase modulator and the first amplifier.

12. The laser device according to claim 8, wherein: The processor controls the sweep width of the frequency sweep signal to adjust the spectral line width.

13. The laser device according to claim 12, wherein: The processor increases the scanning width when the spectral line width is smaller than the target spectral line width, and decreases the scanning width when the spectral line width is larger than the target spectral line width.

14. The laser device according to claim 1, wherein: The laser device further includes a wavelength conversion system that converts the wavelength of the first pulse laser light output from the first amplifier to output a second pulse laser light.

15. The laser device according to claim 14, wherein: The wavelength conversion system includes a plurality of nonlinear crystals, The second pulse laser light having an ultraviolet wavelength is output from the wavelength conversion system.

16. The laser device according to claim 14, wherein: The laser device further includes a second amplifier for amplifying the second pulse laser light.

17. The laser device according to claim 1, wherein: The laser device further includes a measuring device for measuring a spectral line width of the pulse laser light after the pulse is amplified by the first amplifier. The processor controls the modulation signal generator so that the spectral line width measured by the measurer becomes a target spectral line width.

18. The laser device according to claim 1, wherein: The first amplifier comprises a semiconductor optical amplifier.

19. The laser device according to claim 16, wherein: The second amplifier includes an excimer amplifier.

20. A method for manufacturing an electronic device, wherein: The manufacturing method of the electronic device comprises the following steps: generating laser light of ultraviolet wavelength by means of a laser device; outputting the laser light to an exposure device; and exposing the laser on a photosensitive substrate in the exposure device to manufacture an electronic device, The laser device comprises: A semiconductor laser that emits continuous light; a first amplifier that amplifies the continuous light and converts the continuous light into pulse light in synchronization with a light emission trigger signal received from an external device; an optical phase modulator disposed on an optical path of the continuous light between the semiconductor laser and the first amplifier; a modulation signal generator, the output of which is provided to the modulation signal of the optical phase modulator; a processor that controls the modulation signal generator; as well as a wavelength conversion system that converts the wavelength of the first pulse laser output from the first amplifier to output a second pulse laser, The processor enables the modulation signal generator to generate the modulation signal of the same mode synchronized with the light-emitting trigger signal, and by providing the modulation signal of the same mode to the optical phase modulator, the wavelength of the continuous light is modulated within a time equivalent to one pulse of the pulse light, thereby adjusting the spectral line width of the pulse light.

21. A laser device, wherein: The laser device comprises: A semiconductor laser that emits continuous light; a first amplifier that amplifies the continuous light and converts the continuous light into pulse light in synchronization with a light emission trigger signal received from an external device; an optical phase modulator disposed on an optical path of the continuous light between the semiconductor laser and the first amplifier; a modulation signal generator, the output of which is provided to the modulation signal of the optical phase modulator; as well as a processor that controls the modulation signal generator, The processor enables the modulation signal generator to generate the modulation signal of the same mode synchronized with the light-emitting trigger signal, and provides the modulation signal of the same mode to the optical phase modulator to modulate the wavelength of the continuous light within a time equivalent to one pulse of the pulse light, and adjusts the spectral line width of the pulse light by adjusting the power of the modulation signal.

22. The laser device according to claim 21, wherein: The processor increases the power of the modulation signal when the spectral line width is smaller than the target spectral line width, and decreases the power of the modulation signal when the spectral line width is larger than the target spectral line width.

23. The laser device according to claim 22, wherein: The processor determines the power of the modulation signal based on a function representing the relationship between the square root of the power of the modulation signal and the spectral line width.

24. The laser device according to claim 22, wherein: The processor determines the power of the modulation signal based on table data indicating a relationship between a square root of the power of the modulation signal and the spectral line width.

25. The laser device according to claim 21, wherein: The modulation signal generator includes a shift register and an initial value setting circuit. The processor sets the initial value of the shift register so that the spectrum modulated by the optical phase modulator becomes unimodal.

26. The laser device according to claim 21, wherein: The processor roughly adjusts the spectral line width by adjusting the bandwidth of the modulation signal, and finely adjusts the spectral line width by adjusting the power of the modulation signal.

27. The laser device according to claim 21, wherein: The modulation signal generator includes a third amplifier that adjusts the power of the modulation signal according to a control signal from the processor.

28. The laser device according to claim 21, wherein: The modulation signal generator includes a variable attenuator that adjusts the power of the modulation signal according to a control signal from the processor.

29. A method for manufacturing an electronic device, wherein: The manufacturing method of the electronic device comprises the following steps: Using a laser device to generate ultraviolet wavelength laser light; outputting the laser light to an exposure device; and exposing the laser on a photosensitive substrate in the exposure device to manufacture an electronic device, The laser device comprises: A semiconductor laser that emits continuous light; a first amplifier that amplifies the continuous light and converts the continuous light into pulse light in synchronization with a light emission trigger signal received from an external device; an optical phase modulator disposed on an optical path of the continuous light between the semiconductor laser and the first amplifier; a modulation signal generator, the output of which is provided to the modulation signal of the optical phase modulator; as well as a processor that controls the modulation signal generator, The processor enables the modulation signal generator to generate the modulation signal of the same mode synchronized with the light-emitting trigger signal, and provides the modulation signal of the same mode to the optical phase modulator to modulate the wavelength of the continuous light within a time equivalent to one pulse of the pulse light, and adjusts the spectral line width of the pulse light by adjusting the power of the modulation signal.

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