Laser device and method for manufacturing electronic device

Abstract

This laser device comprises a first semiconductor laser which outputs first laser light at a continuous oscillation, a first amplifier which pulsates and amplifies the first laser light, a wavelength conversion system which converts the wavelength of first pulse laser light output from the first amplifier and outputs second pulse laser light, an excimer amplifier which amplifies second pulse laser light, a monitor module which measures the wavelength of third pulse laser light output from the excimer amplifier, and a processor which: calculates a central wavelength that is the average value of a wavelength measurement value at the time of reaching a first target wavelength and a wavelength measurement value at the time of reaching a second target wavelength, and the difference in wavelength therebetween; calculates an average current value of the first semiconductor laser so that the difference between a target central wavelength and the central wavelength becomes small; calculates a current value difference so that the target wavelength difference and the wavelength difference becomes small; calculates a first current value at the time of reaching the first target wavelength and a second current value at the time of reaching the second target wavelength from the average current value and the current value difference; and controls the first semiconductor laser.

Description

[Technical Field]

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

[0002] In recent years, semiconductor exposure devices have been required to improve their resolution in response to the miniaturization and high integration of semiconductor integrated circuits. To this end, the wavelength of light emitted from exposure light sources has been shortened. For example, KrF excimer laser devices that output laser light with a wavelength of approximately 248 nm and ArF excimer laser devices that output laser light with a wavelength of approximately 193 nm are used as gas laser devices for exposure.

[0003] The spectral linewidth of the spontaneously oscillating light from KrF excimer laser devices and ArF excimer laser devices is as wide as 350 to 400 pm. Therefore, if a projection lens is constructed using a material that transmits ultraviolet light, such as KrF and ArF laser light, chromatic aberration may occur. As a result, resolution may decrease. Therefore, it is necessary to narrow the spectral linewidth of the laser light output from the gas laser device to a level where chromatic aberration is negligible. Therefore, a line narrowing module (LNM) containing a line narrowing element (e.g., an etalon or grating) may be installed inside the laser resonator of the gas laser device to narrow the spectral linewidth. Hereinafter, a gas laser device with a narrowed spectral linewidth is referred to as a line narrowing gas laser device. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] U.S. Patent Application Publication No. 2021 / 0226414 [Patent Document 2] International Publication No. 2021 / 015919 [Patent Document 3] Overview of International Publication No. 2020 / 231946

[0005] A laser apparatus according to one aspect of the present disclosure includes a wavelength-tunable first semiconductor laser that outputs a continuous wave first laser beam, a first amplifier that pulses and amplifies the first laser beam to output the first pulsed laser beam, a wavelength conversion system that outputs a second pulsed laser beam by wavelength conversion using the first pulsed laser beam, an excimer amplifier that amplifies the second pulsed laser beam to output a third pulsed laser beam, a monitor module that measures the wavelength of the third pulsed laser beam, and a center wavelength that is an average value of a measured value of the wavelength of the third pulsed laser beam output at the first target wavelength and a measured value of the wavelength of the third pulsed laser beam output at the second target wavelength. a processor that calculates a wavelength difference, which is the difference between the length and the wavelength difference, of the first semiconductor laser, calculates an average current value, which is the average of a first current value of the first semiconductor laser at the first target wavelength and a second current value of the first semiconductor laser at the second target wavelength, so that a difference between a target center wavelength, which is the average value of the first target wavelength and the second target wavelength, and the center wavelength becomes small; calculates a current value difference, which is the difference between the first current value and the second current value, so that a difference between a target wavelength difference, which is the difference between the first target wavelength and the second target wavelength, and the wavelength difference becomes small; calculates a first current value and a second current value from the average current value and the current value difference, and controls the first semiconductor laser to have the first current value when outputting a third pulse laser beam at the first target wavelength and the second current value when outputting a third pulse laser beam at the second target wavelength.

[0006] A method for manufacturing an electronic device according to another aspect of the present disclosure includes a wavelength-tunable first semiconductor laser that outputs a continuous wave first laser beam, a first amplifier that pulses and amplifies the first laser beam to output the first pulsed laser beam, a wavelength conversion system that outputs a second pulsed laser beam by wavelength conversion using the first pulsed laser beam, an excimer amplifier that amplifies the second pulsed laser beam to output a third pulsed laser beam, a monitor module that measures the wavelength of the third pulsed laser beam, and a wavelength conversion system that alternately changes a target wavelength of the third pulsed laser beam between the first target wavelength and a second target wavelength that is longer than the first target wavelength, calculates a wavelength difference that is the difference between a center wavelength that is an average value between a measured value of the wavelength of the third pulsed laser beam output at the first target wavelength and a measured value of the wavelength of the third pulsed laser beam output at the second target wavelength, and calculates a target center wavelength that is an average value between the first target wavelength and the second target wavelength. a processor for controlling the first semiconductor laser to output the third pulsed laser beam at the first target wavelength and the second current value at the second target wavelength, the processor calculating an average current value which is an average of a first current value of the first semiconductor laser at the first target wavelength and a second current value of the first semiconductor laser at the second target wavelength so as to reduce a difference between the central wavelength and the central wavelength, calculating a current difference which is a difference between the first current value and the second current value so as to reduce a difference between a target wavelength difference which is a difference between the first target wavelength and the second target wavelength, and calculating the first current value and the second current value from the average current value and the current difference, and generating the third pulsed laser beam by the laser apparatus including the processor, outputting the third pulsed laser beam to an exposure apparatus, and exposing a photosensitive substrate with the third pulsed laser beam in the exposure apparatus to manufacture an electronic device.

[0007] A laser apparatus according to another aspect of the present disclosure includes a wavelength-tunable first semiconductor laser that outputs a continuous wave first laser beam, a first amplifier that pulses and amplifies the first laser beam to output the first pulsed laser beam, a wavelength conversion system that outputs a second pulsed laser beam by wavelength conversion using the first pulsed laser beam, an excimer amplifier that amplifies the second pulsed laser beam to output a third pulsed laser beam, a monitor module that measures the wavelength of the third pulsed laser beam, and a monitor module that alternately changes a target wavelength of the third pulsed laser beam between the first target wavelength and a second target wavelength that is longer than the first target wavelength, and measures an average value of a measured wavelength of the third pulsed laser beam output at the first target wavelength and a measured wavelength of the third pulsed laser beam output at the second target wavelength. a processor that calculates a wavelength difference, which is the difference between the first target wavelength and the second target wavelength, and a center wavelength that is the average value of the first target wavelength and the second target wavelength; calculates a current difference, which is the difference between a first current value of the first semiconductor laser at the first target wavelength and a second current value of the first semiconductor laser at the second target wavelength, so that the difference between the target wavelength difference and the wavelength difference becomes small; calculates a first current value and a second current value from the reference current value of the first semiconductor laser and the current difference, and controls the first semiconductor laser to use the first current value when outputting a third pulse laser beam at the first target wavelength and the second current value when outputting a third pulse laser beam at the second target wavelength; and controls the temperature of the first semiconductor laser so that the center wavelength becomes the target center wavelength that is the average value of the first target wavelength and the second target wavelength.

[0008] A method for manufacturing an electronic device according to another aspect of the present disclosure includes a wavelength-tunable first semiconductor laser that outputs a continuous wave first laser beam, a first amplifier that pulses and amplifies the first laser beam to output the first pulsed laser beam, a wavelength conversion system that outputs a second pulsed laser beam by wavelength conversion using the first pulsed laser beam, an excimer amplifier that amplifies the second pulsed laser beam to output a third pulsed laser beam, a monitor module that measures the wavelength of the third pulsed laser beam, and a wavelength conversion system that alternately changes the target wavelength of the third pulsed laser beam between the first target wavelength and a second target wavelength that is longer than the first target wavelength, calculates a wavelength difference that is the difference between a center wavelength that is an average value of a measured value of the wavelength of the third pulsed laser beam output at the first target wavelength and a measured value of a wavelength of the third pulsed laser beam output at the second target wavelength, and calculates a center wavelength that is the difference between the first target wavelength and the second target wavelength. a processor that calculates a current difference, which is the difference between a first current value of the first semiconductor laser at the first target wavelength and a second current value of the first semiconductor laser at the second target wavelength, so that a difference between the target wavelength difference and the wavelength difference becomes small, calculates the first current value and the second current value from the reference current value of the first semiconductor laser and the current difference, and controls the first semiconductor laser to output the third pulsed laser beam at the first target wavelength or the second current value when the third pulsed laser beam is output at the second target wavelength, and controls the temperature of the first semiconductor laser so that the center wavelength becomes a target center wavelength that is an average value of the first target wavelength and the second target wavelength; [Brief explanation of the drawings]

[0009] Some embodiments of the present disclosure will now be described, by way of example only, with reference to the accompanying drawings, in which: [Figure 1] FIG. 1 is a graph showing an example of a dual wavelength spectrum applied to dual wavelength exposure. [Figure 2] FIG. 2 shows a schematic configuration of an exposure device connected to a laser device. [Figure 3] FIG. 3 is a top view schematically showing the configuration of a laser device according to a comparative example. [Figure 4] FIG. 4 is a side view schematically showing the configuration of a laser device according to a comparative example. [Figure 5] FIG. 5 shows a schematic configuration of the laser device according to the first embodiment. [Figure 6] FIG. 6 is a flowchart illustrating an example of processing executed by the laser control processor in the first embodiment. [Figure 7] FIG. 7 is a graph showing an example of the relationship between the number of pulses and the wavelength of the excimer laser. [Figure 8] FIG. 8 is a graph showing an example of the relationship between the number of pulses and the current value of the semiconductor laser. [Figure 9] FIG. 9 shows a schematic configuration of a semiconductor laser system. [Figure 10] FIG. 10 is a graph showing an example of a two-wavelength spectrum obtained by two-wavelength control. [Figure 11] FIG. 11 is a flowchart showing Example 1 of the temperature control of the semiconductor laser executed by the laser control processor. [Figure 12] FIG. 12 is a graph showing an example of the relationship between the set temperature of the semiconductor laser and the wavelength after excimer amplification. [Figure 13] FIG. 13 is a flowchart showing Example 2 of the temperature control of the semiconductor laser executed by the laser control processor. [Figure 14] FIG. 14 shows a schematic configuration of a wavelength conversion system. [Figure 15] FIG. 15 is a graph showing examples of wavelength conversion efficiency curves of a KBBF crystal and an LBO crystal. [Figure 16] FIG. 16 shows a schematic configuration of a temperature regulation system for a nonlinear crystal. [Figure 17] FIG. 17 is a graph showing an example of the relationship between the target central wavelength after wavelength conversion and the temperature at which the wavelength conversion efficiency is maximized. [Figure 18] FIG. 18 is a flowchart showing an example of control related to wavelength conversion. [Figure 19] FIG. 19 is a graph showing Example 1 of the relationship between the wavelength conversion efficiency curve and the two-wavelength spectrum of a nonlinear optical crystal. [Figure 20] FIG. 20 is a graph showing Example 2 of the relationship between the wavelength conversion efficiency curve and the two-wavelength spectrum of a nonlinear optical crystal. [Figure 21] FIG. 21 is a flowchart illustrating an example of processing executed by the laser control processor in the second embodiment. [Figure 22] FIG. 22 is a flowchart showing an example of the temperature control of the semiconductor laser executed by the laser control processor in the second embodiment. [Figure 23] FIG. 23 shows a schematic diagram of a modified configuration of a solid seeder. [Figure 24] FIG. 24 shows a schematic configuration of a distributed Bragg reflector type semiconductor laser system. [Figure 25] FIG. 25 shows a schematic configuration of a sampled grating distributed reflector type semiconductor laser system. [Figure 26] FIG. 26 shows a schematic configuration of an exposure apparatus. Embodiment

[0010] -table of contents- 1. Explanation of terms 2. Comparative Example 2.1 Overview of the exposure system 2.1.1 Configuration 2.1.2 Operation 2.2 Laser device according to a comparative example 2.2.1 Configuration 2.2.2 Operation 3. Challenges 4. Embodiment 1 4.1 Laser device description 4.1.1 Configuration 4.1.2 Operation 4.1.2.1 Normal control 4.1.2.2 Dual wavelength control 4.1.3 Actions and Effects 4.1.4 Other 4.2 Example of a semiconductor laser system 4.2.1 Configuration 4.2.2 Operation 4.2.3 Other 4.3 Example of temperature control of semiconductor laser 4.3.1 Flowchart example 1 4.3.2 Flowchart example 2 4.3.3 Actions and Effects 4.4 Example of a wavelength conversion system 4.4.1 Configuration 4.4.2 Operation 4.5 Temperature control system for nonlinear crystals 4.5.1 Configuration 4.5.2 Operation 4.5.3 Other 4.6 Wavelength conversion system control method 4.6.1 Flowchart example 4.6.2 Operation 4.6.3 Actions and Effects 5. Embodiment 2 5.1 Configuration 5.2 Operation 5.3 Actions and Effects 6. Embodiment 3 6.1 Configuration 6.2 Operation 6.3 Other 7. Embodiment 4 7.1 Configuration 7.2 Operation 7.3 Other 8. Embodiment 5 8.1 Configuration 8.2 Operation 9. Manufacturing methods for electronic devices 10.Other Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. The embodiments described below show some examples of the present disclosure and do not limit the content of the present disclosure. Furthermore, not all of the configurations and operations described in each embodiment are necessarily essential as the configurations and operations of the present disclosure. Note that the same components are given the same reference symbols, and redundant explanations will be omitted.

[0011] 1. Explanation of terms In this specification, "two wavelength exposure" means that the wavelength is λ S and λ L This refers to two-wavelength exposure achieved by alternately oscillating the laser at two wavelengths.

[0012] FIG. 1 is a graph for explaining two-wavelength parameters in the case of dual-wavelength exposure. In FIG. 1, the horizontal axis represents wavelength λ and the vertical axis represents light intensity In. As shown in FIG. 1, the wavelength on the short wavelength side in dual-wavelength exposure is λ S , the wavelength on the long wavelength side is λ L Let's say.

[0013] The central wavelength λc of the two-wavelength spectrum is expressed by the following equation (1). λc=(λ L +λ S ) / twenty one)

[0014] The wavelength difference Δλ between the two wavelength spectra is expressed by the following equation (2). Δλ=λ L -λ S (2)

[0015] 2. Comparative Example 2.1 Overview of the exposure system 2.1.1 Configuration 2 is a diagram showing a schematic configuration of an exposure system. The exposure system includes a laser apparatus 10 and an exposure apparatus 300. The laser apparatus 10 includes a laser control processor 12. In this specification, a processor refers to a processing device that includes a storage device in which a control program is stored and a CPU (Central Processing Unit) that executes the control program. The processor is specially configured or programmed to execute various processes included in the present disclosure.

[0016] The laser device 10 is configured to output a pulsed laser beam having a variable oscillation wavelength toward the exposure device 300. The configuration of the laser device 10 will be described later (FIGS. 3 and 4).

[0017] The exposure apparatus 300 includes a beam delivery unit (BDU) 302, a high-reflection mirror 304, an illumination optical system 306, a reticle stage RT, a projection optical system 308, a wafer stage WS, and an exposure control processor 310. A wafer holder WH is provided on the wafer stage WS, and a wafer W is placed on the wafer holder WH.

[0018] The BDU 302 is an optical system that transmits pulsed laser light from the laser device 10 to the exposure device 300. The high-reflection mirror 304 is disposed so that the pulsed laser light that has passed through the BDU 302 enters the illumination optical system 306.

[0019] The illumination optical system 306 is an optical system that shapes the pulsed laser light beam incident from the laser device 10 and guides it to the reticle R placed on the reticle stage RT. The illumination optical system 306 shapes the pulsed laser light beam so that the cross section of the beam is roughly rectangular and the light intensity distribution is roughly uniform, and illuminates the reticle pattern on the reticle R. The projection optical system 308 reduces and projects the pulsed laser light that has passed through the reticle R, forming an image on the wafer W on the wafer holder WH. The wafer W is a photosensitive substrate such as a semiconductor wafer coated with a resist film.

[0020] The exposure control processor 310 is a processing device that includes a storage device in which a control program is stored and a CPU that executes the control program. The exposure control processor 310 oversees the control of the exposure apparatus 300. The exposure control processor 310 is connected to the reticle stage RT and the wafer stage WS. The exposure control processor 310 is also connected to the laser control processor 12.

[0021] 2.1.2 Operation The exposure control processor 310 determines the target short wavelength λ S t and target long wavelength λ LThe laser control processor 12 transmits various parameters including the target pulse energy Et, the target pulse energy Et, and the light emission trigger signal Tr to the laser control processor 12. The laser control processor 12 controls the laser device 10 in accordance with these parameters and signals. That is, the laser control processor 12 controls the laser device 10 so that the wavelength λ of the pulsed laser light output from the laser device 10 is equal to or smaller than the target short wavelength λ. S t or target long wavelength λ L The target wavelength is periodically changed to control the oscillation wavelength so that the wavelength becomes equal to t, and the excitation intensity is controlled so that the pulse energy E becomes equal to the target pulse energy Et, and pulse laser light is output in accordance with the light emission trigger signal Tr.

[0022] In this way, the laser device 10 can achieve a target short wavelength λ at a target pulse energy Et. S t and target long wavelength λ L The laser emits two wavelengths t and outputs pulsed laser light in response to a light emission trigger signal Tr.

[0023] The laser control processor 12 also transmits various data to the exposure control processor 310. The various data includes measurement data such as the wavelength and pulse energy of the pulse laser light output in accordance with the light emission trigger signal Tr.

[0024] The exposure control processor 310 synchronizes the reticle stage RT and the wafer holder WH on the wafer stage WS and translates them in opposite directions, thereby exposing the wafer W to pulsed laser light that reflects the reticle pattern.

[0025] When forming a 3D NAND pattern or a contact hole pattern, exposure is performed so that the waveform of the integrated spectrum becomes a desired two-wavelength spectrum in order to ensure the depth of focus.

[0026] 2.2 Laser device according to a comparative example 2.2.1 Configuration 3 and 4 are a top view and a side view, respectively, that schematically show the configuration of a laser device 10 according to a comparative example. The comparative example in the present disclosure is a configuration that the applicant recognizes as being known only by the applicant, and is not a publicly known example that the applicant acknowledges.

[0027] The laser device 10 shown in Figures 3 and 4 is a single-wavelength, narrow-band excimer laser device, and includes a laser control processor 12, a chamber 14, an LNM 20, an output coupling mirror 30, a beam splitter 32, a monitor module 34, and an exit shutter 36.

[0028] The LNM 20 includes a first prism 22, a second prism 24, a rotation stage 26, and a grating 28. The first prism 22, the second prism 24, and the grating 28 are supported by a holder 22a, a holder 24a, and a holder 28a, respectively. The first prism 22 and the second prism 24 are arranged to function as a beam expander. The grating 28 is Littrow-aligned so that the angle of incidence of the light beam incident on the grating 28 from the second prism 24 matches the diffraction angle of the diffracted light of the desired wavelength.

[0029] The second prism 24 is placed on a rotation stage 26 via a holder 24a. The rotation stage 26 is a stage that can be rotated with a relatively high response speed by a piezoelectric element (not shown). The second prism 24 is positioned so that the angle of incidence on the grating 28 changes when rotated around the V axis by the rotation stage 26.

[0030] The output coupling mirror 30 and the LNM 20 together constitute an optical resonator. The chamber 14 is disposed on the optical path of the optical resonator.

[0031] Chamber 14 includes windows 16a and 16b and a pair of electrodes 18a and 18b. A laser gas is supplied from a gas supply device (not shown) into chamber 14. The laser gas may be, for example, an excimer laser gas containing Ar gas or Kr gas as a rare gas, F gas as a halogen gas, and Ne gas as a buffer gas.

[0032] The electrodes 18a and 18b are arranged in the chamber 14 facing each other in the V direction, with the longitudinal direction of the electrodes 18a and 18b coinciding with the optical path of the optical resonator. The laser device 10 includes a pulse power module (PPM) and a charger (not shown). The PPM includes a switch and a charging capacitor, and is connected to the electrode 18b via a feedthrough made of an electrical insulating member (not shown). The electrode 18a is connected to the grounded chamber 14. The charger charges the charging capacitor of the PPM in accordance with commands from the laser control processor 12.

[0033] The windows 16a and 16b are arranged so that pulsed laser light amplified by discharge excitation between the electrodes 18a and 18b can pass through them.

[0034] The output coupling mirror 30 is coated with a film that reflects part of the pulsed laser light and transmits part of it. The beam splitter 32 is disposed on the optical path of the pulsed laser light output from the output coupling mirror 30. The beam splitter 32 is disposed so that the reflected light from the beam splitter 32 enters the monitor module 34. Note that the beam splitter 32 may be included in the monitor module 34.

[0035] The monitor module 34 includes a pulse energy measuring instrument and a spectrum detector. The pulse energy measuring instrument includes an optical sensor (not shown). The optical sensor may be a photodiode that is resistant to ultraviolet light and has excellent high-speed response. The spectrum detector may detect wavelengths using, for example, an etalon spectrometer.

[0036] The exit shutter 36 is disposed on the optical path of the pulsed laser light output from the laser device 10 to the outside, and is configured to be able to output the pulsed laser light to the outside and to block the light. The pulsed laser light that has passed through the beam splitter 32 is emitted from the laser device 10 via the exit shutter 36 and enters the exposure device 300.

[0037] 2.2.2 Operation The laser control processor 12 determines the target short wavelength λ S t and target long wavelength λ L The laser control processor 12 also receives a light emission trigger signal Tr.

[0038] The laser control processor 12 controls the voltage applied to the electrode 18b based on the received target pulse energy Et, including feedback control based on the pulse energy measured by the monitor module 34.

[0039] Under the control of the laser control processor 12, a pulsed high voltage is applied to electrode 18b from the PPM. When high voltage is applied to electrode 18b, a discharge occurs in the discharge space between electrodes 18a and 18b. The energy of this discharge excites the laser gas in chamber 14 and causes it to transition to a higher energy level. When the excited laser gas subsequently transitions to a lower energy level, it emits light with a wavelength corresponding to the difference in energy levels.

[0040] Light generated within chamber 14 exits chamber 14 as a light beam through windows 16a and 16b. The light beam exiting window 16a has its beam width expanded by first prism 22 and second prism 24 in a plane parallel to the HZ plane, which is a plane perpendicular to the V axis. The light beam transmitted through first prism 22 and second prism 24 enters grating 28.

[0041] A light beam incident on the grating 28 is reflected by the multiple grooves of the grating 28 and diffracted in a direction according to the wavelength of the light.

[0042] The first prism 22 and the second prism 24 reduce the beam width of the light beam returned from the grating 28 in a plane parallel to the HZ plane, and return the light beam to the inside of the chamber 14 through the window 16a.

[0043] The output coupling mirror 30 transmits a portion of the light beam emitted from the window 16 b and reflects another portion back into the chamber 14 .

[0044] In this way, the light beam emitted from chamber 14 travels back and forth between LNM 20 and output coupling mirror 30. This light beam is amplified each time it passes through the discharge space in chamber 14. In addition, this light beam is narrowed in band each time it is reflected by LNM 20. The laser-oscillated, narrowed-band light beam is output from output coupling mirror 30 as pulsed laser light.

[0045] The monitor module 34 measures the pulse energy and wavelength of the pulsed laser light reflected by the beam splitter 32 and transmits the measured pulse energy and wavelength to the laser control processor 12 .

[0046] The pulsed laser light transmitted through the beam splitter 32 is output from the laser device 10 via an exit shutter 36 .

[0047] The laser control processor 12 changes the oscillation wavelength by controlling the angle of incidence on the grating 28 using the rotation stage 26 on which the second prism 24 is arranged. The laser control processor 12 measures the wavelength with a spectrum monitor 126 (see FIG. 6) in the monitor module 34 and calculates the target wavelength (λ S t and λ LBy controlling in this manner, the oscillation wavelength of the pulsed laser light output from the laser device 10 is adjusted to the target short wavelength λ t for each pulse. S t and target long wavelength λ L t and is controlled.

[0048] 3. Challenges In order to generate an exposure spectrum waveform with two wavelengths, it was necessary to change the wavelength for each pulse with high precision. Also, when an optical element such as the second prism 24 of the LNM 20 is rotated by the rotation stage 26 for each pulse, as the repetition frequency (4 kHz or more) of the laser device 10 increases, it becomes difficult to change the wavelength of the output pulse laser light to the two target wavelengths (λ S t and λ L t), it was difficult to stabilize each with high precision.

[0049] 4. Embodiment 1 4.1 Laser device description 4.1.1 Configuration 5 is a schematic diagram showing the configuration of a laser device 100 according to the first embodiment. In FIG. 5, the laser device 100 includes a solid-state seeder 102 and an excimer amplifier 112, and the spectrum of the pulsed laser light output from the laser device 100 is a two-wavelength spectrum, with the two target wavelengths being target short wavelengths λ S t and target long wavelength λ L Here is an example where t and

[0050] The laser device 100 includes a laser control processor 12A, a solid-state seeder 102 serving as a master oscillator (MO), an excimer amplifier 112 serving as a power amplifier (PA), a monitor module 34A, and an exit shutter 36.

[0051] The solid-state seeder 102 includes a semiconductor laser system 104 that outputs pulsed laser light, a solid-state amplifier 106 that amplifies the pulsed laser light, a wavelength conversion system 108, and a solid-state seeder control processor 110.

[0052] The configuration of the semiconductor laser system 104 will be described in detail later (see FIG. 9). The semiconductor laser system 104 includes, for example, a semiconductor laser 132 (see FIG. 9) that outputs a CW (Continuous Wave) laser beam having a wavelength of approximately 773.6 nm, and a semiconductor optical amplifier (SOA) 136 (see FIG. 9). The oscillation wavelength of the semiconductor laser 132 can be changed by controlling the temperature of a semiconductor laser element 138 (see FIG. 9) and / or the value of the current flowing through the semiconductor laser element 138.

[0053] The SOA 136 pulses and amplifies the CW laser light output from the semiconductor laser 132. By passing a pulse current through the SOA 136, the SOA 136 pulse-amplifies the CW laser light and outputs pulse-amplified pulsed laser light PL1.

[0054] The solid-state amplifier 106 includes a titanium sapphire crystal (not shown) and a pumping pulse laser (not shown). The titanium sapphire crystal is disposed on the optical path of the pulsed laser light PL1 pulse-amplified by the SOA 136. The pumping pulse laser is a laser device that outputs second harmonic light of a YLF laser. YLF (yttrium lithium fluoride) is a solid-state laser crystal expressed by the chemical formula LiYF4.

[0055] The wavelength conversion system 108 includes a nonlinear crystal and converts the wavelength of the incident pulsed laser light to generate a fourth harmonic. The configuration of the wavelength conversion system 108 will be described later (see FIG. 14).

[0056] The solid state seeder control processor 110 controls the semiconductor laser system 104 and the solid state amplifier 106 based on input from the laser control processor 12A.

[0057] The excimer amplifier 112 includes a chamber 113, a pulsed power module (PPM) 117, a charger 119, a convex mirror 120, and a concave mirror 122. The chamber 113 includes windows 114a and 114b, a pair of electrodes 115a and 115b, and an electrical insulating member 116. An ArF laser gas containing, for example, Ar gas, F gas, and Ne gas is introduced into the chamber 113.

[0058] The PPM 117 includes a switch 118 and a charging capacitor (not shown). A charger 119 holds electrical energy to be supplied to the PPM 117. The charger 119 is connected to the charging capacitor. The PPM 117 is connected to an electrode 115b in the chamber 113 via a feedthrough in an electrical insulator 116. The electrode 115a is connected to ground potential.

[0059] The convex mirror 120 and the concave mirror 122 are arranged so that the pulsed laser light PL2 output from the wavelength conversion system 108 passes through the discharge space between the electrodes 115a and 115b three times to expand the beam.

[0060] The monitor module 34A includes beam splitters 32A and 124, a spectrum monitor 126, and an optical sensor 128. The beam splitter 32A is disposed on the optical path of the pulsed laser beam PL3 output from the excimer amplifier 112 so that the pulsed laser beam PL3 is reflected by the beam splitter 32A and enters the beam splitter 124. The beam splitter 32A may be disposed outside the monitor module 34A, similar to the beam splitter 32 shown in FIG. 3 .

[0061] The beam splitter 124 is disposed so that the pulsed laser light PL3 ​​reflected by the beam splitter 124 enters the spectrum monitor 126 and so that the pulsed laser light PL3 ​​transmitted through the beam splitter 124 enters the optical sensor 128.

[0062] The spectrum monitor 126 monitors the spectrum of the incident pulsed laser beam PL3 and detects the wavelength of the incident pulsed laser beam PL3. The spectrum monitor 126 may be, for example, an etalon spectrometer. The etalon spectrometer includes a diffuser plate that diffuses the sample light, an etalon, a condenser lens disposed on the exit side of the etalon, and a photodiode array disposed on the focal plane of the condenser lens to detect the pattern of interference fringes, and can detect the wavelength by measuring the diameter of the interference fringes.

[0063] The optical sensor 128 is disposed so that the pulsed laser light that has passed through the beam splitter 124 is incident on it. The optical sensor 128 detects the pulse energy of the incident pulsed laser light. The optical sensor 128 may be, for example, a photodiode.

[0064] 4.1.2 Operation 4.1.2.1 Normal control Continuous wave laser light having a wavelength of approximately 773.6 nm is output from the semiconductor laser element 138. When a pulse current is applied to the SOA 136 in response to a trigger signal Tr2, the SOA 136 is pulse-amplified and outputs pulsed laser light PL1. The pulsed laser light PL1 is an example of the "first pulsed laser light" in this disclosure.

[0065] This pulsed laser light PL1 is further amplified by the solid-state amplifier 106.

[0066] The wavelength conversion system 108 converts the pulsed laser light PL1 amplified by the solid-state amplifier 106 into fourth harmonic light with a wavelength of approximately 193.4 nm, and outputs the pulsed laser light PL2. The pulsed laser light PL2 is an example of the "second pulsed laser light" in this disclosure. The fourth harmonic light obtained by the wavelength conversion system 108 is an example of the "first harmonic light" in this disclosure.

[0067] The wavelength of the pulsed laser light PL2 output from the solid-state seeder 102 can be tuned within a range of approximately 193.2 nm to 193.5 nm, which is the amplification wavelength band of the excimer amplifier 112.

[0068] A trigger signal Tr1 is input to the switch 118 of the PPM 117, and a trigger signal Tr2 is input to the SOA 136 and the pumping pulse laser so that a discharge occurs in synchronization with the pulse laser light PL2 output from the solid seeder 102 entering the discharge space of the chamber 113 of the excimer amplifier 112.

[0069] As a result, the pulsed laser light PL2 output from the solid-state seeder 102 is three-pass amplified by the excimer amplifier 112. The excimer amplifier 112 outputs the amplified pulsed laser light PL3. The pulsed laser light PL3 ​​is an example of the "third pulsed laser light" in this disclosure.

[0070] The pulsed laser light PL3 ​​amplified by the excimer amplifier 112 is sampled by the beam splitter 32A of the monitor module 34A, and the pulse energy E and wavelength λ are measured.

[0071] The laser control processor 12A and the solid-state seeder control processor 110 control the oscillation wavelength of the semiconductor laser 132 of the semiconductor laser system 104 so that the wavelength λ of the pulsed laser light PL3 ​​output from the excimer amplifier 112 and measured approaches a target value.

[0072] Furthermore, the laser control processor 12A and the solid-state seeder control processor 110 control the charging voltage of the charger 119 so that the pulse energy E of the pulsed laser light PL3 ​​output from the excimer amplifier 112 and measured approaches a target value.

[0073] 4.1.2.2 Dual wavelength control FIG. 6 is a flowchart showing an example of processing executed by the laser control processor 12A in the first embodiment.

[0074] In step S11, the laser control processor 12A reads the target two-wavelength control parameter data from the exposure control processor 310. The target two-wavelength control parameter data includes the target short wavelength λ St and target long wavelength λ L t included. Target short wavelength λ S t is an example of the "first target wavelength" in this disclosure, and the target long wavelength λ L t is an example of a "second target wavelength" in this disclosure.

[0075] In step S12, the laser control processor 12A calculates the target center wavelength λct and the target wavelength difference Δλt of the two-wavelength spectrum using the following equations.

[0076] λct=(λ S t+λ L t) / 2 Δλt=λ L t-λ S t In step S13, the laser control processor 12A sets initial values ​​for the average current value Ic and the current value difference ΔI of the current flowing through the semiconductor laser 132. The initial value of the average current value Ic is set to a reference current value Ics (Ic=Ics). The reference current value Ics is a current value at which the semiconductor laser 132 can oscillate and at which the wavelength and performance of the semiconductor laser element 138 can be maintained even if the current is changed within a range that changes the wavelength. The reference current value Ics may be a central value in the variable range of the current flowing through the semiconductor laser 132.

[0077] The initial value of the current difference ΔI may be set to, for example, ΔI0. The current difference ΔI may be set to the initial value ΔI0 in such a manner that the current difference ΔI is proportional to the wavelength difference Δλ.

[0078] In step S14, the laser control processor 12A determines the current value I to be applied to the semiconductor laser 132 during short wavelength oscillation. S and the current value I flowing through the semiconductor laser element 138 during long wavelength oscillation. L and are calculated using the following formulas.

[0079] I S =Ic-ΔI / 2 I L =Ic+ΔI / 2 That is, the laser control processor 12A calculates the current value I by subtracting 1 / 2 of the current difference ΔI from the average current value Ic. S The current value I is calculated by adding 1 / 2 of the current difference ΔI to the average current value Ic. L is required.

[0080] Next, in step S15, the laser control processor 12A sets the command current value I of the semiconductor laser 132 to I S Set to.

[0081] In step S16, the laser control processor 12A determines whether or not the monitor module 34A has detected excimer laser light. If the excimer laser light has not been detected (step S16: No), the laser control processor 12A waits until the excimer laser light is detected. If the excimer laser light has been detected (step S16: Yes), the laser control processor 12A proceeds to step S17.

[0082] In step S17, the laser control processor 12A determines the wavelength λ of the excimer laser light on the short wavelength side based on the information from the monitor module 34A. S Measure.

[0083] Steps S15 to S17 are processes for measuring and controlling the wavelength when the wavelength is short.

[0084] In step S18, the laser control processor 12A sets the command current value I of the semiconductor laser element 138 to I L Set to.

[0085] In step S19, the laser control processor 12A determines whether or not the monitor module 34A has detected excimer laser light. If the excimer laser light has not been detected (step S19: No), the laser control processor 12A waits until the excimer laser light is detected. If the excimer laser light has been detected (step S19: Yes), the laser control processor 12A proceeds to step S20.

[0086] In step S20, the laser control processor 12A determines the wavelength λ of the excimer laser light on the long wavelength side based on the information from the monitor module 34. L Measure.

[0087] Steps S18 to S20 are processes for measuring and controlling the wavelength when the wavelength is long.

[0088] Next, in step S21, the laser control processor 12A calculates the wavelength λ obtained in step S17. S and the wavelength λ obtained in step S20 L Based on the measured values, the central wavelength λc and wavelength difference Δλ of the two-wavelength spectrum are calculated using equations (1) and (2).

[0089] In step S22, the laser control processor 12A calculates the difference δλc between the central wavelength λc of the two-wavelength spectrum and the target central wavelength of the two-wavelength spectrum using the following equation.

[0090] δλc=λc-λct In step S23, the laser control processor 12A calculates the difference δΔλc between the wavelength difference Δλ and the target wavelength difference Δλt using the following equation.

[0091] δΔλc=Δλ-Δλt Steps S21 to S23 are processes for evaluating the two-wavelength spectrum.

[0092] In step S24, the laser control processor 12A calculates the average current value Ica of the semiconductor laser 132 at which the difference δλc approaches zero.

[0093] In step S25, the laser control processor 12A calculates the difference ΔIa in the current values ​​of the semiconductor laser 132 at which the difference δΔλc approaches zero.

[0094] In step S26, the laser control processor 12A sets the value of the average current value Ic to Ica obtained in step S24 to update the value of the average current value Ic, and sets the value of the current value difference ΔI to ΔIa obtained in step S25 to update the value of the current value difference ΔI.

[0095] Steps S24 to S26 are processes for calculating and setting the correction value of the current for the semiconductor laser 132 based on the evaluation result of the two-wavelength spectrum.

[0096] In step S27, the laser control processor 12A determines whether or not to continue the two-wavelength control. If the two-wavelength control is to be continued (step S27: Yes), the laser control processor 12A proceeds to step S28. If the two-wavelength control is not to be continued (step S27: No), the laser control processor 12A ends the processing of this flowchart.

[0097] In step S28, the laser control processor 12A determines whether or not to update the dual-wavelength control parameter. If the dual-wavelength control parameter is not to be updated (step S28: No), the laser control processor 12A returns the process to step S14. If the dual-wavelength control parameter is to be updated (step S28: Yes), the laser control processor 12A returns the process to step S11.

[0098] 7 is a timing chart showing an example of the relationship between the number of pulses and wavelength of excimer laser light output from the laser device 100. The horizontal axis represents the number of pulses (or time), and the vertical axis represents the wavelength. As shown in FIG. 7, the laser device 100 outputs a pulse having a wavelength λ on the short wavelength side for each pulse. S and the excimer laser light with a wavelength λ L Here, the odd-numbered pulses are output alternately at wavelengths λ on the short wavelength side. S The excimer laser light of the even-numbered pulses has a wavelength λ L In this example, the excimer laser beam has a wavelength λ L , the even-numbered pulses have a wavelength λ on the shorter wavelength side Smay be.

[0099] As shown in FIG. 7, the excimer laser light output from the laser device 100 has a wavelength λ S , the wavelength on the long wavelength side λ L Each of these can vary from pulse to pulse with respect to the two target wavelengths. S , λ L The wavelength difference Δλ and the center wavelength λc calculated from the above may also vary.

[0100] 8 is a timing chart showing an example of the relationship between the number of pulses of excimer laser light output from the laser device 100 and the current value of the semiconductor laser 132. In FIG. 8, the horizontal axis represents the number of pulses (or time), and the vertical axis represents the current value. The horizontal axis in FIG. 8 corresponds to the horizontal axis in FIG. 7, and odd-numbered pulses have a wavelength λ on the short wavelength side. S , the even-numbered pulses have a wavelength λ on the longer wavelength side L 8 shows an example of two-wavelength control of excimer laser light. As shown in FIG. 8, the laser device 100 controls the current value I flowing through the semiconductor laser 132 to a current value I S and the current value I at long wavelength L and alternately change to.

[0101] The wavelength control for periodically changing the two wavelengths is performed as follows, as explained in the flowchart of FIG.

[0102] The laser device 100 measures the wavelength λ for each pulse. S and λ L , the wavelength difference Δλ between the most recent two pulses (corresponding to one wavelength change period) is calculated, and this is fed back to the difference ΔI in the current value of the semiconductor laser 132. That is, the laser control processor 12A corrects the difference ΔI in the current value based on the difference δΔλ between the target wavelength difference Δλt and the most recent wavelength difference Δλ, and calculates the current value I for the next short wavelength oscillation. S and the current value I during long wavelength oscillation L This is reflected in the control of the

[0103] The laser device 100 also measures the wavelength λS and λ L The laser control processor 12A calculates the central wavelength λc of the two most recent wavelengths from the calculated values ​​and feeds it back to the average current value Ic of the semiconductor laser element 138. That is, the laser control processor 12A corrects the average current value Ic based on the difference δλc between the target central wavelength λct and the most recent central wavelength λc, and calculates the current value Ic at the time of the next short wavelength oscillation. S and the current value I during long wavelength oscillation L This is reflected in the control of the

[0104] Current value I during short wavelength oscillation S is an example of the "first current value" in this disclosure, and the current value I L is an example of a "second current value" in the present disclosure. Laser control processor 12A is an example of a "processor" in the present disclosure.

[0105] 4.1.3 Actions and Effects According to the laser device 100 of the first embodiment, a configuration of the laser device 100 including a solid-state seeder 102 including a wavelength-tunable semiconductor laser 132 and an excimer amplifier 112 is adopted, and the wavelength λ measured for each pulse alternately changes to the target short wavelength λ for each pulse. S t and target long wavelength λ L The current value I flowing through the semiconductor laser 132 is controlled so that the wavelengths approach t, ​​respectively. This makes it possible to perform high-precision two-wavelength exposure even at a repetition rate of 4 kHz or more.

[0106] 4.1.4 Other In the first embodiment, the CW light output from the semiconductor laser 132 is converted into a pulsed laser light by passing a pulsed current through the SOA 136, but the method for generating the pulsed laser light is not limited to this example. For example, the CW light output from the semiconductor laser 132 may be amplified into a pulsed laser light by exciting the pumping light of the titanium sapphire crystal of the solid-state amplifier 106 with the pulsed light.

[0107] The solid-state seeder 102 may include a CW semiconductor laser and a pulser, and may also include a system that controls the current flowing through the semiconductor laser to change the wavelength. Alternatively, an optical shutter may be used to generate optical pulses instead of the SOA 136. An example of the optical shutter may be a combination of an EO (Electro-Optical) Pockels cell and a polarizer.

[0108] In the first embodiment, an example of a multi-pass amplifier is shown as the excimer amplifier 112, but the excimer amplifier 112 is not limited to a multi-pass amplifier, and may be, for example, an amplifier equipped with an optical resonator such as a Fabry-Perot resonator or a ring resonator.

[0109] In the first embodiment, an example of the solid-state seeder 102 and the ArF excimer amplifier is shown, but the present invention is not limited to this embodiment. A combination of an excimer amplifier using KrF laser gas and a solid-state seeder oscillating in the amplification wavelength region of the KrF excimer may also be used. Specifically, the solid-state seeder may include a semiconductor laser system that outputs pulsed laser light with a wavelength of approximately 745.2 nm, a solid-state amplifier, and a wavelength conversion system that converts the wavelength of the pulsed laser light to third harmonic light with a wavelength of approximately 248.4 nm. The nonlinear crystals used in the wavelength conversion system in this case may be an LBO crystal that converts the wavelength to second harmonic light and a CLBO crystal that generates the sum frequency of the second harmonic light and the fundamental wave.

[0110] 4.2 Example of a semiconductor laser system 4.2.1 Configuration 9 schematically illustrates the configuration of a semiconductor laser system 104. The semiconductor laser system 104 includes a single-longitudinal-mode distributed feedback (DFB) semiconductor laser 132, a semiconductor laser control processor 134, and an SOA 136. The semiconductor laser 132 includes a semiconductor laser element 138, a Peltier element 148, a temperature sensor 150, a current controller 152, and a temperature controller 154. The semiconductor laser element 138 includes a first cladding layer 140, an active layer 142, and a second cladding layer 144, and includes a grating 146 at the boundary between the active layer 142 and the second cladding layer 144. The semiconductor laser 132 is an example of a "first semiconductor laser" in this disclosure.

[0111] The Peltier element 148 and the temperature sensor 150 are fixed to the semiconductor laser element 138. The semiconductor laser control processor 134 is provided with signal lines for receiving data on the current value I and the set temperature Ts from the solid-state seeder control processor 110. The current controller 152 is provided with a signal line for receiving data on the current value I from the semiconductor laser control processor 134. The temperature controller 154 is provided with a signal line for receiving data on the set temperature Ts from the semiconductor laser control processor 134.

[0112] 4.2.2 Operation The central oscillation wavelength of the semiconductor laser 132 can be changed by changing the set temperature Ts of the semiconductor laser element 138 and / or the current value I flowing through the semiconductor laser element 138. The solid-state seeder control processor 110 obtains the set temperature Ts and the current value I from the laser control processor 12A and sends them to the semiconductor laser control processor 134. The semiconductor laser control processor 134 controls the temperature controller 154 and the current controller 152, respectively, in accordance with the set temperature Ts and the current value I.

[0113] When changing the oscillation wavelength of the semiconductor laser 132 at high speed, the value of the current I flowing through the semiconductor laser element 138 is changed at high speed, thereby making it possible to change the wavelength of the CW laser light at high speed.

[0114] The solid-state seeder control processor 110 also receives a trigger signal Tr2 from the laser control processor 12 A. When the trigger signal Tr2 is input to the solid-state seeder 102, a pulse signal is input to the SOA 136.

[0115] By passing a pulse current corresponding to this pulse signal through the semiconductor of the SOA 136, the CW laser light output from the semiconductor laser 132 is pulse-amplified, and pulsed laser light PL1 is output. The CW laser light having a wavelength of approximately 773.6 nm output from the semiconductor laser 132 is an example of a "first laser light" in this disclosure. The SOA 136 is an example of a "first amplifier" in this disclosure.

[0116] 10 is a graph showing an example of a two-wavelength spectrum of pulsed laser light PL1 output from the semiconductor laser system 104. By changing the current value I for each pulse, as shown in FIG. S Pulsed laser light PL1 with wavelength λ1 L The pulsed laser beam PL1 can be output alternately.

[0117] 4.2.3 Other The SOA 136 is not limited to a mode in which it performs pulsing and amplification, and may, for example, perform CW amplification by passing a direct current through the SOA 136. In that case, the subsequent solid-state amplifier 106 is an amplifier that performs pulse amplification.

[0118] 4.3 Example of temperature control of semiconductor laser 4.3.1 Flowchart example 1 Fig. 11 is a flowchart showing Example 1 of the temperature control of the semiconductor laser executed by the laser control processor 12 A. Fig. 11 shows an example of controlling the temperature of the semiconductor laser 132 based on the target center wavelength λct.

[0119] In step S31, the laser control processor 12A reads data on the target central wavelength λct.

[0120] In step S32, the laser control processor 12A calls up the relational expression between the set temperature Ts of the semiconductor laser when a current of the reference current value Ics is passed through the semiconductor laser 132 and the wavelength λ after excimer amplification.

[0121] In step S33, the laser control processor 12A calculates the set temperature Ts of the semiconductor laser 132 corresponding to the target center wavelength λct from the above relational expression.

[0122] In step S34, the laser control processor 12A sets the set temperature of the semiconductor laser 132 to Ts.

[0123] In step S35, the laser control processor 12A determines whether or not to continue temperature control of the semiconductor laser 132. If the temperature control is not to be continued (step S35: No), the laser control processor 12A ends the flowchart of Fig. 11. If the temperature control is to be continued (step S35: Yes), the laser control processor 12A proceeds to step S36.

[0124] In step S36, the laser control processor 12A determines whether or not to change the target central wavelength λct. If the target central wavelength λct is not to be changed (step S36: No), the laser control processor 12A returns the process to step S35. If the target central wavelength λct is to be changed (step S36: Yes), the laser control processor 12A returns the process to step S31.

[0125] 12 is a graph showing an example of the relationship between the set temperature Ts of the semiconductor laser 132 and the wavelength λ after excimer amplification for a reference current value Ics. In FIG. 12, the horizontal axis represents the wavelength λ after excimer amplification, and the vertical axis represents the set temperature Ts of the semiconductor laser 132. As the relational expression used in step S32 of FIG. 11, the relationship shown in FIG. 12 may be measured in advance, and an approximate line or an approximate curve may be obtained from the measured data. Furthermore, table data may be used instead of the approximate line or the approximate curve as the relational expression.

[0126] 4.3.2 Flowchart example 2 Fig. 13 is a flowchart showing Example 2 of the temperature control of the semiconductor laser 132 executed by the laser control processor 12A. Fig. 13 shows an example of controlling the temperature of the semiconductor laser 132 based on the average current value Ic.

[0127] In step S41, the laser control processor 12A reads the average current value Ic of the semiconductor laser 132.

[0128] In step S42, the laser control processor 12A calculates the difference ΔIcs between the average current value Ic and the reference current value Ics using the following equation.

[0129] δIcs=Ic-Ics In step S43, the laser control processor 12A determines whether the absolute value of the difference ΔIcs is equal to or less than the allowable value ΔIstr. That is, the laser control processor 12A determines whether |ΔIcs|≦ΔIstr is satisfied. If |ΔIcs|≦ΔIstr is satisfied (step S43: Yes), the laser control processor 12A returns the process to step S41. If |ΔIcs|≦ΔIstr is not satisfied (step S43: No), the semiconductor laser control processor 134 proceeds to step S44.

[0130] In step S44, the laser control processor 12A changes the set temperature Ts of the semiconductor laser 132 so that the difference ΔIcs approaches zero.

[0131] In step S45, the laser control processor 12A determines whether or not to continue temperature control of the semiconductor laser 132. If the temperature control is to be continued (step S45: Yes), the laser control processor 12A returns the process to step S41. If the temperature control is not to be continued (step S45: No), the laser control processor 12A ends the process of the flowchart in FIG.

[0132] 4.3.3 Actions and Effects When the target center wavelength λct is changed significantly, it may not be possible to control the wavelength λ after excimer amplification using only the current value I of the semiconductor laser 132. By setting the temperature of the semiconductor laser 132 as shown in Figure 11 or 13, it is possible to maintain the average current value Ic flowing through the semiconductor laser 132 near the reference current value Ics even when the target center wavelength λct is changed significantly.

[0133] As a result, even if the target wavelength of the two-wavelength spectrum is changed significantly, it is possible to precisely align the wavelengths to two wavelengths for each pulse.

[0134] 4.4 Example of a wavelength conversion system 4.4.1 Configuration 14 is a schematic diagram of a wavelength conversion system 108. The wavelength conversion system 108 includes a KBBF crystal 162, an LBO crystal 164, rotation stages 166 and 168 as actuators, and a rotation stage driver 170 as a controller for the actuators. "KBBF" is represented by the chemical formula KBe2BO3F2. "LBO" is represented by the chemical formula LiB3O5. The KBBF crystal 162 is an example of a "first nonlinear crystal" in this disclosure.

[0135] The KBBF crystal 162 is placed on a rotation stage 166. The LBO crystal 164 is placed on a rotation stage 168. In order to rotate the wavelength conversion element at high speed, each of the rotation stages 166 and 168 is a rotation stage including a piezoelectric element. A rotation stage driver 170 controls the angle of each of the rotation stages 166 and 168.

[0136] The actuator may also be a heater for controlling the temperature of the nonlinear crystal, and the controller may be a temperature controller.

[0137] 4.4.2 Operation The pulsed laser light PL1 input to the wavelength conversion system 108 is incident on the LBO crystal 164. The LBO crystal 164 converts the pulsed laser light PL1 having a wavelength of approximately 773.6 nm into pulsed laser light having a wavelength of approximately 386.8 nm, which is second harmonic light.

[0138] The KBBF crystal 162 converts the pulsed laser light having a wavelength of approximately 386.8 nm output from the LBO crystal 164 into pulsed laser light PL2 having a wavelength of approximately 193.4 nm, which is second harmonic light.

[0139] The pulsed laser light PL2 converted to have a wavelength of approximately 193.4 nm is output from the wavelength conversion system 108.

[0140] In the case of single-wavelength oscillation, the laser control processor 12A controls the angles of incidence of the KBBF crystal 162 and the LBO crystal 164 so as to maximize the wavelength conversion efficiency at the target wavelength λt, i.e., to achieve phase matching. The angles of incidence of the KBBF crystal 162 and the LBO crystal 164 are controlled by the rotation of rotation stages 166 and 168.

[0141] Fig. 15 is a graph schematically showing the wavelength conversion efficiency curves of the KBBF crystal 162 and the LBO crystal 164. In Fig. 15, the horizontal axis represents the wavelength λ after wavelength conversion, and the vertical axis represents the wavelength conversion efficiency η. As shown in Fig. 15, the wavelength conversion efficiency of the KBBF crystal 162, which is the downstream nonlinear crystal, decreases when the wavelength λ after wavelength conversion deviates to some extent. Therefore, when the target wavelength difference Δλt between the two wavelength spectra is large, the pulse energy of the wavelength-converted light may decrease if the incident angle of the KBBF crystal 162 is not controlled to achieve phase matching for each pulse.

[0142] 4.5 Temperature control system for nonlinear crystals 4.5.1 Configuration 16 is a schematic diagram showing an example of the configuration of a nonlinear crystal temperature adjustment system 180. The temperature adjustment system 180 shown in FIG. 16 can be applied to temperature adjustment of the KBBF crystal 162 and the LBO crystal 164 in FIG.

[0143] The nonlinear crystal temperature regulation system 180 includes a nonlinear crystal 182 , a nonlinear crystal holder 184 , a temperature sensor 186 , a heater 188 , and a temperature controller 190 .

[0144] The nonlinear crystal 182 is fixed to a nonlinear crystal holder 184. The temperature sensor 186 is disposed in the nonlinear crystal holder 184 near the nonlinear crystal 182. The heater 188 is disposed within the nonlinear crystal holder 184.

[0145] Furthermore, a rotation stage 192 for controlling the angle of incidence of the nonlinear crystal 182 and a rotation stage controller 194 for controlling the rotation stage 192 may be additionally provided.

[0146] 4.5.2 Operation The temperature controller 190 receives data on the temperature Tn of the nonlinear crystal 182 from the laser control processor 12A. The temperature controller 190 controls the power of the heater 188 so that the temperature Tn is the received temperature Tn, thereby controlling the temperature of the nonlinear crystal 182 to approach Tn.

[0147] The laser control processor 12A determines and sets the temperature Tn of the nonlinear crystal 182 from the target wavelength λt based on data on the relationship between wavelength and temperature at which the wavelength conversion efficiency of the nonlinear crystal 182 is maximized. The data may be measured in advance, and an approximate straight line or approximate curve may be calculated and stored, or may be stored as table data.

[0148] If phase matching cannot be achieved by temperature control alone, phase matching may be achieved by controlling the angle of incidence with the rotation stage 192 .

[0149] Fig. 17 is data stored in the laser control processor 12A on the relationship between the wavelength and temperature at which the wavelength conversion efficiency of the nonlinear crystal 182 is maximized, and is a graph showing the relationship between the target center wavelength after wavelength conversion and the temperature T at which the wavelength conversion efficiency is maximized. In Fig. 17, the horizontal axis represents the target center wavelength after wavelength conversion, and the vertical axis represents the temperature T at which the wavelength conversion efficiency is maximized. As shown in Fig. 17, when the target center wavelength after wavelength conversion is λct, the temperature at which the wavelength conversion efficiency is maximized is Tn.

[0150] 4.5.3 Other If the nonlinear crystal 182 is a KBBF crystal or an LBO crystal, there is no need to place the nonlinear crystal 182 in a cell. On the other hand, if the nonlinear crystal 182 is a CLBO crystal, it is hygroscopic, so the nonlinear crystal 182 and the nonlinear crystal holder 184 must be placed in a cell (not shown) and controlled at, for example, 120 to 170°C. "CLBO" has the chemical formula CsLiBO 10 It is expressed as:

[0151] 4.6 Wavelength conversion system control method 4.6.1 Flowchart example FIG. 18 is a flowchart showing an example of control of the wavelength conversion system 108 executed by the laser control processor.

[0152] In step S51, the laser control processor 12A reads the calculated values ​​of the target center wavelength λct and the target wavelength difference Δλt of the two-wavelength spectrum from the two-wavelength control parameter data received from the exposure control processor 310.

[0153] In step S52, the laser control processor 12A determines whether the target wavelength difference Δλt between the two-wavelength spectra acquired in step S51 is within the allowable range Δλtr for a decrease in wavelength conversion efficiency. That is, the laser control processor 12A determines whether Δλt≦Δλtr is satisfied. If Δλt≦Δλtr is satisfied (step S52: Yes), the laser control processor 12A proceeds to step S53. If Δλt≦Δλtr is not satisfied (step S52: No), the laser control processor 12A proceeds to step S56.

[0154] In step S53, the laser control processor 12A controls the angles of incidence of the KBBF crystal 162 and the LBO crystal 164 so that the wavelength at which the wavelength conversion efficiency is maximized becomes the target central wavelength λct obtained in step S51.

[0155] In step S54, the laser control processor 12A determines whether or not to continue the two-wavelength control. If the two-wavelength control is to be continued (step S54: Yes), the laser control processor 12A proceeds to step S55. If the two-wavelength control is not to be continued (step S54: No), the laser control processor 12A ends the processing of the flowchart in FIG.

[0156] In step S55, the laser control processor 12A determines whether the target center wavelength λct or the target wavelength difference Δλt of the two-wavelength spectrum has changed. If the target center wavelength λct or the target wavelength difference Δλt of the two-wavelength spectrum has not changed (step S55: No), the laser control processor 12A returns the process to step S53. If the target center wavelength λct or the target wavelength difference Δλt of the two-wavelength spectrum has changed (step S55: Yes), the laser control processor 12A returns the process to step S51.

[0157] In step S56, the laser control processor 12A determines that the wavelength at which the wavelength conversion efficiency is maximized is the target short wavelength λ S The incident angles of the KBBF crystal 162 and the LBO crystal 164 are controlled so that t is satisfied.

[0158] In step S57, the laser control processor 12A determines whether or not excimer laser light has been detected by the spectrum monitor 126. If excimer laser light has not been detected (step S57: No), the laser control processor 12A waits until excimer laser light is detected. If excimer laser light has been detected (step S57: Yes), the laser control processor 12A proceeds to step S58.

[0159] In step S58, the laser control processor 12A determines that the wavelength at which the wavelength conversion efficiency is maximized is the target long wavelength λ L The incident angles of the KBBF crystal 162 and the LBO crystal 164 are controlled so that t is satisfied.

[0160] In step S59, the laser control processor 12A determines whether or not excimer laser light has been detected by the spectrum monitor 126. If excimer laser light has not been detected (step S59: No), the laser control processor 12A waits until excimer laser light is detected. If excimer laser light has been detected (step S59: Yes), the laser control processor 12A proceeds to step S60.

[0161] In step S60, the laser control processor 12A determines whether or not to continue the two-wavelength control. If the two-wavelength control is to be continued (step S60: Yes), the laser control processor 12A proceeds to step S61. If the two-wavelength control is not to be continued (step S60: No), the laser control processor 12A ends the processing of the flowchart in FIG.

[0162] In step S61, the laser control processor 12A determines whether the target center wavelength λct or the target wavelength difference Δλt of the two-wavelength spectrum has changed. If the target center wavelength λct or the target wavelength difference Δλt of the two-wavelength spectrum has not changed (step S61: No), the laser control processor 12A returns the process to step S56. If the target center wavelength λct or the target wavelength difference Δλt of the two-wavelength spectrum has changed (step S61: Yes), the laser control processor 12A returns the process to step S51.

[0163] 4.6.2 Operation 18, the laser control processor 12A determines whether the decrease in wavelength conversion efficiency caused by the target wavelength difference Δλt between the two wavelength spectra is within an allowable range (step S52). The target wavelength difference Δλt is, for example, in the range of 1 pm to 2 pm. Depending on the result of this determination, the laser control processor 12A switches the control of the incident angles of the wavelength conversion elements, the KBBF crystal 162 and the LBO crystal 164.

[0164] 19 and 20 are graphs showing the relationship between the wavelength λ after excimer amplification and the wavelength conversion efficiency. In Fig. 19 and Fig. 20, the horizontal axis represents the wavelength λ after excimer amplification, and the vertical axis represents the wavelength conversion efficiency. In the figures, "WCE(LBO)" represents the wavelength conversion efficiency curve of the LBO crystal 164, and "WCE(KBBF)" represents the wavelength conversion efficiency curve of the KBBF crystal 162.

[0165] As shown in FIG. 19, if the target wavelength difference Δλt of the two-wavelength spectrum is within a range in which a decrease in wavelength conversion efficiency is suppressed, the laser control processor 12A controls the angles of incidence of the KBBF crystal 162 and the LBO crystal 164 so as to maximize the wavelength conversion efficiency at the target center wavelength λct of the two-wavelength spectrum (step S53 in FIG. 18).

[0166] On the other hand, as shown in FIG. 20, when the target wavelength difference Δλt of the two-wavelength spectrum is larger than the range in which the decrease in wavelength conversion efficiency is suppressed, the laser control processor 12A synchronizes with the target short wavelength λ for each pulse. S t and target long wavelength λL At least the angle of incidence of the KBBF crystal 162, which is a nonlinear crystal arranged at the most downstream of the wavelength conversion system 108, is controlled so that the wavelength t becomes t (steps S56 and S58 in FIG. 18).

[0167] If the target wavelength difference Δλt between the two wavelength spectra is larger, the target short wavelength λ S t and target long wavelength λ L The incident angle of the LBO crystal 164, which is the second nonlinear crystal from the downstream side, may also be controlled so that t is obtained.

[0168] 4.6.3 Actions and Effects As explained in FIG. 18, if the target wavelength difference Δλt is within the allowable range, the change in wavelength conversion efficiency is suppressed, and therefore the pulse energy and the wavelength λ of the spectrum of the two wavelengths can be controlled. S and λ L is controlled with high precision for each pulse.

[0169] When the target wavelength difference Δλt≦1 pm to 2 pm, it is possible to form a resist pattern for a contact hole and provide a margin for the process by increasing the depth of focus.

[0170] When the target wavelength difference Δλt is greater than 1 pm to 2 pm, it can also be used to form thick-film resist in the 3D semiconductor manufacturing process.

[0171] 5. Embodiment 2 5.1 Configuration The configuration of the second embodiment may be the same as that of the first embodiment.

[0172] 5.2 Operation Fig. 21 is a flowchart showing an example of processing executed by the laser control processor 12A in embodiment 2. Differences between Fig. 21 and Fig. 6 will be described.

[0173] In FIG. 6, after the average current value Ic is set to the initial value, the reference current value Ics, in step S13, the average current value Ica is calculated so that the difference Δλc between the center wavelength λc of the two-wavelength spectrum and the target center wavelength approaches 0, and the value of the average current value Ic is dynamically updated (steps S22, S25, and S26). However, in FIG. 21, after the average current value Ic is set to the reference current value Ics in step S13, the value of this average current value Ic is fixed to the reference current value Ics.

[0174] That is, in FIG. 21, steps S22 and S24 are deleted, and step S26 is replaced with step S26B.

[0175] In step S26B, the laser control processor 12A replaces the value of the current difference ΔI with ΔIa, thereby updating the current difference ΔI.

[0176] The other steps may be the same as those in FIG.

[0177] Fig. 22 is a flowchart showing an example of temperature control of the semiconductor laser 132 executed by the laser control processor 12A in embodiment 2. Fig. 22 shows an example of feeding back the central wavelength λc of the two-wavelength spectrum to the set temperature Ts of the semiconductor laser 132.

[0178] In step S211, the laser control processor 12A reads the target central wavelength λct of the two-wavelength spectrum.

[0179] In step S212, the laser control processor 12A measures the central wavelength λc of the two-wavelength spectrum for each period, and reads a predetermined number of samples of data for calculating the central wavelength λc.

[0180] In step S213, the laser control processor 12A calculates the averaged center wavelength λcav of the measured two-wavelength spectrum. That is, the laser control processor 12A calculates the average value (center wavelength λcav) from the data of the center wavelength λc of the predetermined number of samples read out in step S212.

[0181] Steps S214 and S215 are the same processes as steps S32 and S33 in FIG.

[0182] In step S216, the laser control processor 12A calculates the difference δλcav between the averaged center wavelength λcav and the target center wavelength λct of the two-wavelength spectrum using the following equation.

[0183] δλcav=λcav-λct In step S217, the laser control processor 12A calculates the set temperature Ts of the semiconductor laser 132 at which the difference Δλcav approaches 0. The laser control processor 12A obtains the set temperature Ts based on the relationship described with reference to FIG.

[0184] Next, in step S218, the laser control processor 12A sets the set temperature of the semiconductor laser to Ts.

[0185] In step S219, the laser control processor 12A determines whether or not to continue temperature control of the semiconductor laser 132. If temperature control is to be continued (step S219: Yes), the laser control processor 12A proceeds to step S220. If temperature control is not to be continued (step S219: No), the laser control processor 12A ends the processing of the flowchart in FIG.

[0186] In step S220, the laser control processor 12A determines whether or not to change the target center wavelength λct. If the target center wavelength λct is not to be changed (step S220: No), the laser control processor 12A returns the process to step S212. If the target center wavelength λct is to be changed (step S220: Yes), the laser control processor 12A returns the process to step S211.

[0187] It is difficult to control the temperature of the semiconductor laser 132 at high speed for each pulse. Therefore, as shown in the flowchart of Fig. 22, it is preferable to average the center wavelength λc of the measured two-wavelength spectrum over a predetermined number of samples and feed back the average value to the set temperature Ts of the semiconductor laser 132 so that it approaches the target center wavelength λct.

[0188] 5.3 Actions and Effects According to the second embodiment, the same effects as those of the first embodiment can be obtained.

[0189] 5.4 Other The average value of the central wavelength λc of the measured two-wavelength spectrum is not limited to the arithmetic average, and may be a moving average value. 6. Embodiment 3 6.1 Configuration In the third embodiment, a modification of the solid-state seeder 102 will be described. A solid-state seeder 200 shown in Fig. 23 can be applied instead of the solid-state seeder 102 shown in Fig. 5. The solid-state seeder 200 includes a first solid-state laser device 202, a second solid-state laser device 208, a dichroic mirror 220, a wavelength conversion system 222, and a solid-state seeder control processor 232.

[0190] The solid-state seeder 200 is a system configuration in which pulsed laser light PL1 having a wavelength of approximately 1554 nm output from a first solid-state laser device 202 and pulsed laser light PL4 having a wavelength of approximately 257.6 nm output from a second solid-state laser device 208 are converted into pulsed laser light PL2 having a wavelength of approximately 193.4 nm by two-fold sum frequency conversion in a wavelength conversion system 222.

[0191] The first solid-state laser device 202 includes a first semiconductor laser system 204 and a first solid-state amplifier 206. In Fig. 23, notations with numbers such as "semiconductor laser system 1" and "solid-state amplifier 1" respectively represent the first semiconductor laser system and the first solid-state amplifier.

[0192] 10, the first semiconductor laser system 204 can have a similar configuration to the semiconductor laser system 104, but has a different oscillation wavelength from the semiconductor laser system 104. The first semiconductor laser system 204 includes a semiconductor laser 132 that oscillates in a single longitudinal mode CW at a wavelength of approximately 1554 nm, and an SOA 136. Here, the semiconductor laser 132 and the SOA 136 used in the first semiconductor laser system 204 are referred to as the first semiconductor laser and the first SOA.

[0193] The first solid-state amplifier 206 is an optical parametric amplifier (OPA), such as PPLN (periodically poled lithium niobate) or PPKTP (periodically poled potassium titanyl phosphate).

[0194] The first solid-state amplifier 206 is configured to pulse amplify the seed light by inputting a 1030 nm pulsed laser light, which will be described later, as pump light and a laser light output from the first semiconductor laser system 204 as seed light.

[0195] The second solid-state laser device 208 includes a second semiconductor laser system 210, a second solid-state amplifier 212, two nonlinear crystals for wavelength conversion to fourth harmonic light, an LBO crystal 214 and a first CLBO crystal 216, and a dichroic mirror 218. The fourth harmonic light output from the first CLBO crystal 216 is an example of "second harmonic light" in this disclosure. The LBO crystal 214 and the first CLBO crystal 216 are examples of "second nonlinear crystals" in this disclosure.

[0196] The second semiconductor laser system 210 can have a configuration similar to that of the semiconductor laser system 104 shown in FIG. 10 , but has a different oscillation wavelength from that of the semiconductor laser system 104. The second semiconductor laser system 210 includes a semiconductor laser 132 that oscillates in a single longitudinal mode at a wavelength of approximately 1030 nm, and an SOA 136. Here, the semiconductor laser 132 and the SOA 136 used in the second semiconductor laser system 210 are referred to as the second semiconductor laser and the second SOA. The continuous wave laser light having a wavelength of approximately 1030 nm output from the second semiconductor laser is an example of the "second laser light" in this disclosure. The second SOA is an example of the "second amplifier" in this disclosure.

[0197] The second solid-state amplifier 212 includes, for example, a Yb fiber amplifier or a Yb:YAG crystal.

[0198] The dichroic mirror 218 is disposed on the optical path between the LBO crystal 214 and the first CLBO crystal 216, and has high transmittance for pulsed laser light with a wavelength of approximately 515 nm and high reflectance for pulsed laser light with a wavelength of approximately 1030 nm. The dichroic mirror 218 is disposed so that the highly reflected pulsed laser light with a wavelength of approximately 1030 nm enters the first solid-state amplifier 206 as pump light for the first solid-state amplifier 206.

[0199] The wavelength conversion system 222 includes a second CLBO crystal 224, a third CLBO crystal 226, and rotation stages 228 and 230. The second CLBO crystal 224 and the third CLBO crystal 226 are placed on rotation stages 228 and 230, which include piezoelectric elements, respectively, and are configured so that the incident angle of each crystal can be changed at high speed.

[0200] The dichroic mirror 220 is configured to highly reflect the pulsed laser light having a wavelength of approximately 1554 nm output from the first solid-state laser device 202 and to highly transmit the pulsed laser light having a wavelength of approximately 257.6 nm output from the second solid-state laser device 208, and is positioned so that both pulsed laser lights enter the wavelength conversion system 222 coaxially.

[0201] 6.2 Operation In the solid-state seeder 200, the wavelength of the pulsed laser light PL4 output from the second solid-state laser device 208 is fixed, and the wavelength of the pulsed laser light PL1 output from the first solid-state laser device 202 is changed for each pulse, thereby changing the wavelength of the pulsed laser light PL2 output from the wavelength conversion system 222.

[0202] The operation of the second solid-state laser device 208 is as follows: The laser control processor 12A fixes the oscillation wavelength of the second solid-state laser device 208 to 1030 nm. That is, the laser control processor 12A keeps the current value of the second semiconductor laser in the second semiconductor laser system 210 constant, causes the second semiconductor laser to oscillate continuously, and causes the second semiconductor laser to output CW laser light.

[0203] Furthermore, in response to the trigger signal Tr2, the laser control processor 12A causes the CW laser light to be pulse-amplified by the second SOA and the second solid-state amplifier 212. The second solid-state amplifier 212 outputs pulsed laser light PL5 having a wavelength of 1030 nm. The pulsed laser light PL5 is an example of the "fifth pulsed laser light" in this disclosure.

[0204] Pulsed laser light PL5 having a wavelength of 1030 nm output from the second solid-state amplifier 212 is converted into second harmonic light having a wavelength of 515 nm by the LBO crystal 214. The second harmonic light having a wavelength of 515 nm is highly transmitted through the dichroic mirror 218 and converted into pulsed laser light PL4 having a wavelength of 257.6 nm by the first CLBO crystal 216. The second solid-state laser device 208 is an example of a "solid-state laser device" in the present disclosure. The pulsed laser light PL4 is an example of a "fourth pulsed laser light" in the present disclosure.

[0205] Here, the dichroic mirror 218 highly reflects the 1030 nm pulsed laser light that could not be wavelength converted by the LBO crystal 214 and makes it incident as pump light for the first solid-state amplifier 206 of the first solid-state laser device 202 .

[0206] In response to this, the laser control processor 12A controls the current value of the first semiconductor laser in the first semiconductor laser system 204, thereby alternately changing the wavelength of the pulsed laser light PL1 output from the first solid-state laser device 202 for each pulse around 1554 nm.

[0207] The pulsed laser light PL1 having a wavelength of approximately 1554 nm output from the first solid-state laser device 202 and the pulsed laser light PL4 having a wavelength of 257.6 nm output from the first CLBO crystal 224 are sum-frequency converted into a pulsed laser light having a wavelength of approximately 220.9 nm by the second CLBO crystal 224. Furthermore, the pulsed laser light having a wavelength of approximately 220.9 nm and the pulsed laser light having a wavelength of 1554 nm are sum-frequency converted into a pulsed laser light PL2 having a wavelength of approximately 193.4 nm by the third CLBO crystal 226. Then, the wavelength is alternately changed from λ S and λ L The pulsed laser beam PL2 is outputted.

[0208] The laser control processor 12A performs control as shown in the flowchart of FIG. 6 to obtain the target two-wavelength spectrum λ S t and λ L The wavelength is controlled alternately for each pulse so as to approach t.

[0209] 6.3 Other In a system using a solid seeder 200, by performing control as shown in the flowchart of embodiment 2 (FIG. 21), it is also possible to control the wavelength of the pulsed laser light PL2 for each pulse so that the wavelength approaches the target two wavelengths.

[0210] 7. Embodiment 4 7.1 Configuration 24 schematically illustrates a configuration example of a distributed Bragg reflector (DBR) semiconductor laser system 240. The semiconductor laser system 240 can be applied to the semiconductor laser system 104 in FIG. 6, the first semiconductor laser system 204 in FIG. 23, or the second semiconductor laser system 210.

[0211] The semiconductor laser system 240 includes a single-longitudinal mode distributed Bragg reflector (DBR) semiconductor laser 242 instead of the semiconductor laser 132 in FIG.

[0212] The semiconductor laser element 244 includes a feedback layer 246, an active layer 248, and a phase adjustment region 250 between the first cladding layer 140 and the second cladding layer 144. The feedback layer 246 includes a grating 146 at the boundary between the feedback layer 246 and the second cladding layer 144. The phase adjustment region 250 is disposed between the feedback layer 246 and the active layer 248.

[0213] In the semiconductor laser device 244, electrodes 252, 254, and 256 are disposed on the first cladding layer 140. The electrodes 252, 254, and 256 are provided corresponding to the feedback layer 246, the active layer 248, and the phase adjustment region 250, respectively.

[0214] The other configuration is the same as in Fig. 9. However, current controller 152 is connected to electrodes 252, 254, and 256 by wiring, and is configured so as to be able to independently control the value of the current flowing through each wiring.

[0215] 7.2 Operation The central oscillation wavelength of the semiconductor laser 242 can be changed by changing the set temperature Ts of the semiconductor laser element 244 and / or the current value Itu1 or Itu2 flowing through the semiconductor laser element 244. The solid-state seeder control processor 110 acquires the set temperature Ts, the current value Itu1, the current value Itu2, and the current value Iemit from the laser control processor 12A and sends them to the semiconductor laser control processor 134. The semiconductor laser control processor 134 controls the temperature controller 154 in accordance with the set temperature Ts, and controls the current controller 152 in accordance with the current value Itu1, the current value Itu2, and the current value Iemit.

[0216] When the oscillation wavelength of the semiconductor laser 242 is changed at high speed within a fine adjustment range, the current value Itu2 flowing through the phase adjustment region 250 is changed at high speed, whereby the wavelength of the CW laser light can be changed at high speed.

[0217] When changing the oscillation wavelength of the semiconductor laser 242 at high speed and over a wide range, the wavelength of the CW laser light can be changed at high speed by quickly changing the current value Itu1 flowing through the grating 146. However, since there are wavelengths that cannot be oscillated, the current value Itu2 to the phase adjustment region 250 may also be used in combination.

[0218] To oscillate the semiconductor laser 242 and obtain a desired power, a current value Iemit flowing through the active layer 248 is input.

[0219] The solid-state seeder control processor 110 also receives a trigger signal Tr2 from the laser control processor 12 A. When the trigger signal Tr2 is input to the solid-state seeder 200, a pulse signal is input to the SOA 136.

[0220] When the trigger signal Tr2 is input to the solid-state seeder 102 or the solid-state seeder 200, a pulse signal is input to the SOA 136.

[0221] By passing a pulse current corresponding to this pulse signal through the semiconductor of the SOA 136, the CW laser light output from the semiconductor laser element 244 is pulse-amplified and pulsed laser light PL1 is output.

[0222] 7.3 Other The SOA 136 may also perform CW amplification by passing a direct current through it, in which case the subsequent solid-state amplifier 106, the first solid-state amplifier 206, or the second solid-state amplifier 212 is an amplifier that performs pulse amplification.

[0223] 7.4 Actions and Effects 10, the current value I, which is a parameter for adjusting wavelength tunability and output power, is the same, so changing the wavelength also changes the output power. In contrast, the parameter that mainly determines the output power of the distributed Bragg reflector semiconductor laser 242 is Iemit flowing in the active layer 248, so the output power fluctuates little even when the current value Itu1 or Itu2 is changed.

[0224] The wavelength tunability of the semiconductor laser 242 and the semiconductor laser 132 is caused by a change in the refractive index in response to a change in the carrier density in the laser waveguide, so that the carrier density is almost fixed at the oscillation threshold carrier density above the laser oscillation threshold current in the distributed feedback semiconductor laser 132. Therefore, above the laser oscillation threshold current, the amount of wavelength tunability is relatively small even if the injection current is increased or decreased.

[0225] In contrast, in the distributed Bragg reflector semiconductor laser 242, the carrier density of the active layer 248 is almost fixed at the oscillation threshold carrier density at a laser oscillation threshold current or higher, as in the semiconductor laser 132, but the portion of the grating 146 and the phase adjustment region 250 do not have laser gain, so the carrier density can vary greatly depending on the injected current. Therefore, the distributed Bragg reflector semiconductor laser 242 has a larger wavelength tunability than the distributed Bragg reflector semiconductor laser 132.

[0226] 8. Embodiment 5 8.1 Configuration 25 schematically illustrates a configuration example of a sampled grating distributed Bragg reflector (SG-DBR) semiconductor laser system 260. The semiconductor laser system 260 can be applied to the semiconductor laser system 104 in FIG. 6, the first semiconductor laser system 204 in FIG. 24, or the second semiconductor laser system 210.

[0227] The semiconductor laser system 260 includes a single longitudinal mode sampled grating distributed reflector (SG-DBR) semiconductor laser 262 instead of the semiconductor laser 132 in FIG.

[0228] The semiconductor laser element 264 includes an active layer 248 , a phase adjustment region 250 , a first feedback layer 266 , and a second feedback layer 268 between the first cladding layer 140 and the second cladding layer 144 .

[0229] The first feedback layer 266 includes a first grating 146a at the interface between the first feedback layer 266 and the second cladding layer 144. The second feedback layer 268 includes a second grating 146b at the interface between the second feedback layer 268 and the second cladding layer 144. The active layer 248 and the phase adjustment region 250 are disposed between the first feedback layer 266 and the second feedback layer 268.

[0230] In the semiconductor laser device 264, electrodes 254, 256, 270, and 272 are disposed on the first cladding layer 140. The electrodes 254, 256, 270, and 272 are provided corresponding to the active layer 248, the phase adjustment region 250, the first feedback layer 266, and the second feedback layer 268, respectively. The other configuration is the same as in Fig. 9. However, current controller 152 is connected to electrodes 254, 256, 270, and 272 by wiring, and is configured so as to be able to independently control the value of the current flowing through each wiring.

[0231] 8.2 Operation The central oscillation wavelength of the semiconductor laser 262 can be changed by changing the set temperature Ts of the semiconductor laser element 264 and / or at least one of the current values ​​Itu1, Itu2, and Itu3 flowing through the semiconductor laser element 264. The solid-state seeder control processor 110 acquires the set temperature Ts, the current values ​​Itu1, Itu2, Itu3, and Iemit from the laser control processor 12A and transmits them to the semiconductor laser control processor 134. The semiconductor laser control processor 134 controls the current controller 152 in accordance with the current values ​​Itu1, Itu2, Itu3, and Iemit.

[0232] When the oscillation wavelength of the semiconductor laser 262 is changed at high speed within a fine adjustment range, the current value Itu2 flowing through the phase adjustment region 250 is changed at high speed, whereby the wavelength of the CW laser light can be changed at high speed.

[0233] When changing the oscillation wavelength of the semiconductor laser 262 at high speed and over a wide range, the wavelength of the CW laser light can be changed at high speed by quickly changing the current value Itu1 flowing through the first grating 146a and the current value Itu3 flowing through the second grating 146b. However, since there are wavelengths that cannot be oscillated, the current value Itu2 to the phase adjustment region 250 may also be used.

[0234] To oscillate the semiconductor laser 262 and obtain a desired power, a current value Iemit flowing through the active layer 248 is input.

[0235] The laser control processor 12A commands the solid state seeder control processor 110 or 232 the current values ​​Iemit, Itu1, Itu2, and the set temperature Ts.

[0236] When the trigger signal Tr2 is input to the solid-state seeder 102 or the solid-state seeder 200, a pulse signal is input to the SOA 136.

[0237] By passing a pulse current corresponding to this pulse signal through the semiconductor of the SOA 136, the CW laser light output from the semiconductor laser element 264 is pulse-amplified and a pulsed laser light is output.

[0238] 8.4 Actions and Effects The SG-DBR semiconductor laser 262 has a feature that the output power fluctuates little even when the current value Itu1, Itu2, or Itu3 is changed, since the parameter that mainly determines the output power is Iemit that flows in the active layer.

[0239] The semiconductor laser 262 has a slightly different corrugation period between the first grating 146a and the second grating 146b, so that the wavelength can be tuned over a much wider range than the distributed reflection type semiconductor laser 242, with some being able to tune by more than 100 nm.

[0240] 9. Manufacturing methods for electronic devices 26 shows a schematic configuration example of an exposure apparatus 300. The exposure apparatus 300 includes an illumination optical system 306 and a projection optical system 308. The illumination optical system 306 illuminates the reticle pattern on the reticle stage RT with laser light incident from the laser apparatus 100. The projection optical system 308 reduces and projects the laser light that has passed through the reticle R, forming an image on a workpiece (not shown) placed on a workpiece table WT. The workpiece is a photosensitive substrate such as a semiconductor wafer coated with photoresist.

[0241] The exposure apparatus 300 exposes the workpiece with laser light reflecting the reticle pattern by synchronously moving the reticle stage RT and the workpiece table WT in parallel in opposite directions. After the reticle pattern is transferred to the semiconductor wafer through the exposure process described above, a semiconductor device can be manufactured through multiple processes. A semiconductor device is an example of an "electronic device" in this disclosure.

[0242] 10.Other The above description is intended to be illustrative rather than limiting. Thus, it will be apparent to one skilled in the art that modifications can be made to the disclosed embodiments without departing from the scope of the claims. It will also be apparent to one skilled in the art that the disclosed embodiments can be used in combination.

[0243] Terms used throughout this specification and claims should be construed as "open ended" unless expressly stated otherwise. For example, terms such as "comprise," "have," "comprise," and "equip" should be construed as meaning "without excluding the presence of elements other than those listed." In addition, the modifier "a" should be construed as meaning "at least one" or "one or more." In addition, the term "at least one of A, B, and C" should be construed as "A," "B," "C," "A+B," "A+C," "B+C," or "A+B+C." Furthermore, it should be construed as including combinations of these with elements other than "A," "B," and "C."

Claims

1. a first wavelength-tunable semiconductor laser that outputs a first continuous wave laser beam; a first amplifier that pulses and amplifies the first laser beam and outputs a first pulsed laser beam; a wavelength conversion system that outputs a second pulsed laser beam by wavelength conversion using the first pulsed laser beam; an excimer amplifier that amplifies the second pulsed laser beam and outputs a third pulsed laser beam; a monitor module that measures the wavelength of the third pulsed laser beam; Alternately changing the target wavelength of the third pulsed laser beam between a first target wavelength and a second target wavelength that is longer than the first target wavelength; calculating a center wavelength that is an average value between a measured value of the wavelength of the third pulse laser beam output at the first target wavelength and a measured value of the wavelength of the third pulse laser beam output at the second target wavelength, and a wavelength difference that is a difference between the center wavelength and the measured value; calculating an average current value which is an average value of a first current value of the first semiconductor laser at the first target wavelength and a second current value of the first semiconductor laser at the second target wavelength so that a difference between a target central wavelength which is an average value of the first target wavelength and the second target wavelength becomes small; calculating a current value difference that is the difference between the first current value and the second current value so that a difference between a target wavelength difference that is the difference between the first target wavelength and the second target wavelength and the wavelength difference becomes small; a processor that calculates the first current value and the second current value from the average current value and the current value difference, and controls the first semiconductor laser to set the first current value when the third pulse laser beam is output at the first target wavelength, and the second current value when the third pulse laser beam is output at the second target wavelength; A laser device comprising:

2. 10. The laser device according to claim 1, further comprising: The processor: controlling the temperature of the first semiconductor laser so that the average current value becomes a reference current value of the first semiconductor laser; Laser device.

3. 10. The laser device according to claim 1, further comprising: the processor controls the temperature of the first semiconductor laser based on a relationship between the temperature of the first semiconductor laser and the wavelength of the third pulsed laser beam so that the center wavelength becomes the target center wavelength. Laser device.

4. 4. The laser device according to claim 3, The processor: determining a relationship between the temperature of the first semiconductor laser and the wavelength of the third pulsed laser beam by an approximate straight line; Laser device.

5. 4. The laser device according to claim 3, The processor: obtaining an approximation curve of the relationship between the temperature of the first semiconductor laser and the wavelength of the third pulsed laser beam; Laser device.

6. 2. The laser device according to claim 1, the wavelength conversion system includes a first nonlinear crystal and an actuator; The processor: controlling the actuator so that the first nonlinear crystal is phase-matched at the target center wavelength; Laser device.

7. 7. The laser device according to claim 6, the actuator is a rotation stage that controls the angle of incidence onto the first nonlinear crystal; Laser device.

8. 7. The laser device according to claim 6, the actuator is a heater and controls the temperature of the first nonlinear crystal; Laser device.

9. 2. The laser device according to claim 1, The wavelength conversion system includes: a first nonlinear crystal; a rotation stage that rotates the first nonlinear crystal; the processor controls the rotation stage so that the wavelength at which wavelength conversion efficiency is maximized becomes the target wavelength. Laser device.

10. 2. The laser device according to claim 1, the wavelength conversion system outputs the second pulsed laser beam which is a first harmonic beam of the first pulsed laser beam. Laser device.

11. 10. The laser device according to claim 1, further comprising: a solid-state laser device that outputs a fourth pulsed laser beam; the wavelength conversion system performs sum frequency conversion on the first pulse laser beam and the fourth pulse laser beam to output the second pulse laser beam. Laser device.

12. 12. The laser device according to claim 11, The solid-state laser device is a second semiconductor laser that outputs a second continuous wave laser beam; a second amplifier that pulses and amplifies the second laser beam to output a fifth pulsed laser beam; a second nonlinear crystal that receives the fifth pulsed laser beam and outputs second harmonic light, which is the fourth pulsed laser beam; Laser device.

13. 2. The laser device according to claim 1, the first semiconductor laser is at least one of a distributed feedback semiconductor laser, a distributed reflection semiconductor laser, and a sampled grating distributed reflection semiconductor laser; Laser device.

14. 2. The laser device according to claim 1, the first semiconductor laser is a distributed Bragg reflector type semiconductor laser, the processor changes the wavelength of the first semiconductor laser by controlling a current flowing through a phase adjustment region of the distributed Bragg reflector semiconductor laser; Laser device.

15. 2. The laser device according to claim 1, the first semiconductor laser is a sampled grating distributed reflector type semiconductor laser, the processor changes the wavelength of the first semiconductor laser by controlling a current flowing through a phase adjustment region of the sampled grating distributed reflector semiconductor laser; Laser device.

16. A method for manufacturing an electronic device, comprising: a first wavelength-tunable semiconductor laser that outputs a first continuous wave laser beam; a first amplifier that pulses and amplifies the first laser beam and outputs a first pulsed laser beam; a wavelength conversion system that outputs a second pulsed laser beam by wavelength conversion using the first pulsed laser beam; an excimer amplifier that amplifies the second pulsed laser beam and outputs a third pulsed laser beam; a monitor module that measures the wavelength of the third pulsed laser beam; Alternately changing the target wavelength of the third pulsed laser beam between a first target wavelength and a second target wavelength that is longer than the first target wavelength; calculating a center wavelength that is an average value between a measured value of the wavelength of the third pulse laser beam output at the first target wavelength and a measured value of the wavelength of the third pulse laser beam output at the second target wavelength, and a wavelength difference that is a difference between the center wavelength and the measured value; calculating an average current value which is an average value of a first current value of the first semiconductor laser at the first target wavelength and a second current value of the first semiconductor laser at the second target wavelength so that a difference between a target central wavelength which is an average value of the first target wavelength and the second target wavelength becomes small; calculating a current value difference that is the difference between the first current value and the second current value so that a difference between a target wavelength difference that is the difference between the first target wavelength and the second target wavelength and the wavelength difference becomes small; a processor that calculates the first current value and the second current value from the average current value and the current value difference, and controls the first semiconductor laser to set the first current value when the third pulse laser beam is output at the first target wavelength, and the second current value when the third pulse laser beam is output at the second target wavelength, outputting the third pulsed laser beam to an exposure device; a third pulsed laser beam being incident on a photosensitive substrate in the exposure apparatus to produce an electronic device;

17. a first wavelength-tunable semiconductor laser that outputs a first continuous wave laser beam; a first amplifier that pulses and amplifies the first laser beam and outputs a first pulsed laser beam; a wavelength conversion system that outputs a second pulsed laser beam by wavelength conversion using the first pulsed laser beam; an excimer amplifier that amplifies the second pulsed laser beam and outputs a third pulsed laser beam; a monitor module that measures the wavelength of the third pulsed laser beam; Alternately changing the target wavelength of the third pulsed laser beam between a first target wavelength and a second target wavelength that is longer than the first target wavelength; calculating a center wavelength that is an average value between a measured value of the wavelength of the third pulse laser beam output at the first target wavelength and a measured value of the wavelength of the third pulse laser beam output at the second target wavelength, and a wavelength difference that is a difference between the center wavelength and the measured value; calculating a current value difference which is a difference between a first current value of the first semiconductor laser at the first target wavelength and a second current value of the first semiconductor laser at the second target wavelength so that a difference between a target wavelength difference which is a difference between the first target wavelength and the second target wavelength and the wavelength difference becomes small; calculating the first current value and the second current value from a reference current value of the first semiconductor laser and the current value difference, and controlling the first semiconductor laser to use the first current value when outputting the third pulse laser light at the first target wavelength and the second current value when outputting the third pulse laser light at the second target wavelength; a processor that controls the temperature of the first semiconductor laser so that the center wavelength becomes a target center wavelength that is an average value of the first target wavelength and the second target wavelength; A laser device comprising:

18. 18. The laser device of claim 17, a value obtained by subtracting half of the current value difference from the reference current value is the first current value; The second current value is the reference current value plus half of the current value difference. Laser device.

19. A method for manufacturing an electronic device, comprising: a first wavelength-tunable semiconductor laser that outputs a first continuous wave laser beam; a first amplifier that pulses and amplifies the first laser beam and outputs a first pulsed laser beam; a wavelength conversion system that outputs a second pulsed laser beam by wavelength conversion using the first pulsed laser beam; an excimer amplifier that amplifies the second pulsed laser beam and outputs a third pulsed laser beam; a monitor module that measures the wavelength of the third pulsed laser beam; Alternately changing the target wavelength of the third pulsed laser beam between a first target wavelength and a second target wavelength that is longer than the first target wavelength; calculating a center wavelength that is an average value between a measured value of the wavelength of the third pulse laser beam output at the first target wavelength and a measured value of the wavelength of the third pulse laser beam output at the second target wavelength, and a wavelength difference that is a difference between the center wavelength and the measured value; calculating a current value difference which is a difference between a first current value of the first semiconductor laser at the first target wavelength and a second current value of the first semiconductor laser at the second target wavelength so that a difference between a target wavelength difference which is a difference between the first target wavelength and the second target wavelength and the wavelength difference becomes small; calculating the first current value and the second current value from a reference current value of the first semiconductor laser and the current value difference, and controlling the first semiconductor laser to use the first current value when outputting the third pulse laser light at the first target wavelength and the second current value when outputting the third pulse laser light at the second target wavelength; a processor that controls the temperature of the first semiconductor laser so that the center wavelength becomes a target center wavelength that is an average value of the first target wavelength and the second target wavelength; generating the third pulsed laser light by a laser device comprising: outputting the third pulsed laser beam to an exposure device; a third pulsed laser beam being incident on a photosensitive substrate in the exposure apparatus to produce an electronic device;

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