Laser device and manufacturing method for electronic device

Abstract

To provide a laser device which can make the output energy large.SOLUTION: A laser device includes an oscillator that emits pulse-shaped seed light, a first amplifier that amplifies the seed light and emits first amplified light, a first beam splitter that divides the first amplified light into first split light and second split light with lower energy than the first split light, a first delay optical system that delays the second split light, a second amplifier that amplifies the delayed second split light and emits a second amplified light, a beam combiner that combines the first split light and the second amplified light to emit combined light, and a pulse stretcher that extends the pulse width of the combined light.SELECTED DRAWING: Figure 3

Description

Technical Field

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

Background Art

[0002] In recent years, in semiconductor exposure apparatuses, as semiconductor integrated circuits have been miniaturized and highly integrated, an improvement in resolution has been demanded. For this reason, the wavelength of light emitted from an exposure light source has been shortened. For example, as a gas laser device for exposure, a KrF excimer laser device that outputs laser light with a wavelength of about 248 nm and an ArF excimer laser device that outputs laser light with a wavelength of about 193 nm are used.

[0003] The spectral linewidth of the spontaneous emission light of a KrF excimer laser device and an ArF excimer laser device is as wide as 350 to 400 pm. Therefore, when a projection lens is configured with a material that transmits ultraviolet light such as KrF and ArF laser light, chromatic aberration may occur. As a result, the resolution may decrease. Therefore, it is necessary to narrow the spectral linewidth of the laser light output from the gas laser device to such an extent that chromatic aberration can be ignored. For this reason, a narrowbanding module (Line Narrowing Module: LNM) including a narrowbanding element (etalon, grating, etc.) may be provided in the laser resonator of the gas laser device to narrow the spectral linewidth. A gas laser device whose spectral linewidth is narrowed is called a narrowbanded gas laser device.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

[0005] A laser device according to one aspect of the present disclosure includes an oscillator that emits pulsed seed light, a first amplifier that amplifies the seed light and emits first amplified light, a first beam splitter that splits the first amplified light into a first split light and a second split light having less energy than the first split light, a first delay optical system that delays the second split light, a second amplifier that amplifies the delayed second split light and emits second amplified light, a beam combiner that emits combined light obtained by combining the first split light and the second amplified light, and a pulse stretcher that stretches the pulse width of the combined light.

[0006] A method for manufacturing an electronic device according to one aspect of the present disclosure includes generating laser light by a laser device including an oscillator that emits pulsed seed light, a first amplifier that amplifies the seed light and emits first amplified light, a first beam splitter that splits the first amplified light into a first split light and a second split light having less energy than the first split light, a first delay optical system that delays the second split light, a second amplifier that amplifies the delayed second split light and emits second amplified light, a beam combiner that emits combined light obtained by combining the first split light and the second amplified light, and a pulse stretcher that stretches the pulse width of the combined light, outputting the laser light to an exposure device, and exposing the laser light onto a photosensitive substrate in the exposure device to manufacture an electronic device.

Brief Description of the Drawings

[0007] Some embodiments of the present disclosure will be described below by way of example only with reference to the accompanying drawings.

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[0008] <Content> 1. Comparative Example 1.1 Configuration of Exposure Device 200 1.2 Operation of Exposure Device 200 1.3 Configuration of Laser Device 100 1.3.1 First and Second Oscillators MO1 and MO2 1.3.2 First and Second Amplifiers PO1 and PO2 1.3.3 First and Second Pulse Stretchers PS1 and PS2 1.3.4 Others 1.4 Operation of Laser Device 100 1.4.1 First and Second Oscillators MO1 and MO2 1.4.2 First and Second Amplifiers PO1 and PO2 1.4.3 First and second pulse stretchers PS1 and PS2 1.4.4 Others 1.5 Problems of the comparative example 2. Laser device 100a for branching the first amplified light Bpoa 2.1 Configuration 2.2 Operation 2.2.1 Timing control 2.2.2 Energy control 2.3 Function 3. Laser device 100b for further branching the second amplified light Bpob 3.1 Configuration 3.2 Operation 3.2.1 Timing control 3.2.2 Energy control 3.3 Function 4. Laser device 100c for further branching the second split light Bpoa2 4.1 Configuration 4.2 Operation 4.2.1 Timing control 4.2.2 Energy control 4.3 Function 5. Others 5.1 Control of the applied voltage 5.2 Configuration of the delay optical system 5.3 Configuration of the beam combiner COM 5.4 Supplementary

[0009] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. The embodiments described below are examples of the present disclosure and do not limit the content of the present disclosure. Also, not all of the configurations and operations described in the embodiments are essential as the configurations and operations of the present disclosure. Note that the same reference numerals are assigned to the same components, and redundant descriptions are omitted.

[0010] 1. Comparative example FIG. 1 shows the configuration of the exposure system in the comparative example. The comparative example of the present disclosure is a form recognized by the applicant as being known only to the applicant, and is not a publicly known example recognized by the applicant.

[0011] The exposure system includes a laser device 100 and an exposure device 200. The laser device 100 is configured to output laser light B toward the exposure device 200.

[0012] 1.1 Configuration of Exposure Device 200 The exposure device 200 includes an illumination optical system 201 and a projection optical system 202. The illumination optical system 201 illuminates a reticle pattern of a reticle (not shown) disposed on a reticle stage RT with the laser light B incident from the laser device 100. The projection optical system 202 reduces and projects the laser light B that has passed through the reticle and forms an image on a workpiece (not shown) disposed on a workpiece table WT. The workpiece is a photosensitive substrate such as a semiconductor wafer coated with a resist film.

[0013] 1.2 Operation of Exposure Device 200 The exposure device 200 synchronously moves the reticle stage RT and the workpiece table WT in opposite directions parallel to each other. As a result, the workpiece is exposed with the laser light B reflecting the reticle pattern. Through such an exposure process, the reticle pattern is transferred onto the semiconductor wafer. Thereafter, an electronic device can be manufactured through a plurality of processes.

[0014] 1.3 Configuration of Laser Device 100 FIG. 2 shows the configuration of the laser device 100 according to the comparative example. The laser device 100 includes first and second oscillators MO1 and MO2, first and second amplifiers PO1 and PO2, first and second pulse stretchers PS1 and PS2, a beam combiner COM, and a processor 130.

[0015] 1.3.1 First and Second Oscillators MO1 and MO2 The first and second oscillators MO1 and MO2 have the same configuration as each other. Each of the first and second oscillators MO1 and MO2 is a master oscillator including a laser chamber 10, a pair of discharge electrodes 11a and 11b, a narrowbanding module 14, and an output coupling mirror 15.

[0016] The narrowbanding module 14 and the output coupling mirror 15 constitute a laser resonator. The laser chamber 10 is disposed in the optical path of the laser resonator. Windows 10a and 10b are provided at both ends of the laser chamber 10. Inside the laser chamber 10, discharge electrodes 11a and 11b are disposed. A pulse power supply 12 is connected to the discharge electrode 11a. The laser chamber 10 is filled with a laser gas containing, for example, argon gas or krypton gas as a rare gas, fluorine gas as a halogen gas, neon gas as a buffer gas, and the like.

[0017] The narrowbanding module 14 includes a prism 14b and a grating 14c. The prism 14b is disposed in the optical path of the light emitted from the window 10a. The grating 14c is disposed in the optical path of the light transmitted through the prism 14b. The output coupling mirror 15 is a partial reflection mirror and is disposed in the optical path of the light emitted from the window 10b.

[0018] 1.3.2 First and Second Amplifiers PO1 and PO2 The first amplifier PO1 is disposed in the optical path of the seed light B1 output from the first oscillator MO1, and the second amplifier PO2 is disposed in the optical path of the seed light B1 output from the second oscillator MO2. The first and second amplifiers PO1 and PO2 have the same configuration as each other. Each of the first and second amplifiers PO1 and PO2 is a power oscillator including a laser chamber 20, a pair of discharge electrodes 21a and 21b, a rear mirror 24, and an output coupling mirror 25.

[0019] Each of the rear mirror 24 and the output coupling mirror 25 is a partially reflective mirror. The reflectivity of the rear mirror 24 is set higher than that of the output coupling mirror 25. The laser resonator is constituted by the rear mirror 24 and the output coupling mirror 25. The laser chamber 20 is arranged in the optical path of the laser resonator. Windows 20a and 20b are provided at both ends of the laser chamber 20. Inside the laser chamber 20, discharge electrodes 21a and 21b are arranged. A pulse power supply 22 is connected to the discharge electrode 21a. The laser chamber 20 is filled with the same laser gas as the laser chamber 10.

[0020] The discharge directions between the discharge electrodes 11a and 11b and between the discharge electrodes 21a and 21b are the V direction or the -V direction. The output direction of the seed light B1 from the output coupling mirror 15 is the Z direction. The V direction and the Z direction are perpendicular to each other, and the directions perpendicular to both of them are the H direction and the -H direction.

[0021] 1.3.3 First and second pulse stretchers PS1 and PS2 The first pulse stretcher PS1 is arranged in the optical path of the laser light B2 output from the first amplifier PO1, and the second pulse stretcher PS2 is arranged in the optical path of the laser light B2 output from the second amplifier PO2. The first and second pulse stretchers PS1 and PS2 have the same configuration as each other. Each of the first and second pulse stretchers PS1 and PS2 includes first to fourth concave mirrors 31 to 34 and a beam splitter 35. Each of the first to fourth concave mirrors 31 to 34 is a spherical mirror.

[0022] 1.3.4 Others High reflection mirrors 61 and 62 are arranged in the optical paths of the laser lights Bps1 and Bps2 output from the first and second pulse stretchers PS1 and PS2, respectively.

[0023] The beam combiner COM is arranged in the space including the optical paths of both the laser lights Bps1 and Bps2 reflected by the high reflection mirrors 61 and 62, respectively.

[0024] The processor 130 is a processing device that includes a memory 131 in which a control program is stored and a CPU (central processing unit) 132 that executes the control program. The processor 130 is specially configured or programmed to execute various processes included in the present disclosure.

[0025] 1.4 Operation of the laser device 100 1.4.1 First and second oscillators MO1 and MO2 In each of the first and second oscillators MO1 and MO2, when a high-voltage pulse generated by the pulse power supply 12 is applied to the discharge electrode 11a, a discharge occurs inside the laser chamber 10. Due to the energy of this discharge, the laser medium inside the laser chamber 10 is excited and transitions to a high energy level. When the excited laser medium then transitions to a low energy level, it emits light with a wavelength corresponding to the energy level difference. The light generated inside the laser chamber 10 exits the laser chamber 10 through the windows 10a and 10b.

[0026] The light emitted from the window 10a of the laser chamber 10 is expanded in the beam width in the H direction by the prism 14b and enters the grating 14c. The light incident on the grating 14c from the prism 14b is reflected by a plurality of grooves of the grating 14c and diffracted in a direction corresponding to the wavelength of the light. The prism 14b reduces the beam width in the H direction of the diffracted light from the grating 14c and returns the light to the laser chamber 10 through the window 10a.

[0027] The output coupling mirror 15 transmits and outputs a part of the light emitted from the window 10b of the laser chamber 10 and reflects the other part back into the laser chamber 10 through the window 10b.

[0028] In this way, the light emitted from the laser chamber 10 reciprocates between the narrowbanding module 14 and the output coupling mirror 15, and is amplified each time it passes through the discharge space inside the laser chamber 10. This light is narrowbanded each time it is reflected by the narrowbanding module 14. In this way, the laser-oscillated and narrowbanded light is output as the seed light B1 from the output coupling mirror 15.

[0029] 1.4.2 First and Second Amplifiers PO1 and PO2 In each of the first and second amplifiers PO1 and PO2, a high-voltage pulse generated by the pulse power supply 22 is applied to the discharge electrode 21a. The time from when the processor 130 transmits an oscillation trigger signal to the pulse power supply 12 until when it transmits an oscillation trigger signal to the pulse power supply 22 is set so that the timing at which the seed light B1 enters the inside of the laser chamber 20 is synchronized with the timing at which discharge occurs inside the laser chamber 20.

[0030] The seed light B1 reciprocates between the rear mirror 24 and the output coupling mirror 25, and is amplified each time it passes through the discharge space inside the laser chamber 20. The amplified laser light B2 is output from the output coupling mirror 25.

[0031] 1.4.3 First and Second Pulse Stretchers PS1 and PS2 In each of the first and second pulse stretchers PS1 and PS2, the beam splitter 35 transmits a part of the laser light B2 incident in the Z direction from the output coupling mirror 25 as the first output light in the Z direction, and reflects the other part in the V direction.

[0032] The first to fourth concave mirrors 31 to 34 sequentially reflect the laser beam B2 reflected in the V direction by the beam splitter 35 and make it incident on the beam splitter 35 in the V direction. At this time, the beam cross-section of the laser beam B2 incident on the beam splitter 35 in the Z direction is imaged on the beam splitter 35 at a 1:1 size by the first to fourth concave mirrors 31 to 34. The beam splitter 35 reflects a part of the laser beam B2 incident from the fourth concave mirror 34 in the V direction as the second output light in the Z direction and transmits the other part in the V direction.

[0033] There is a time difference corresponding to the time for light to make one round in the delay optical path formed by the first to fourth concave mirrors 31 to 34 between the first output light and the second output light. By spatially overlapping the first output light and the second output light, laser beams Bps1 and Bps2 with an extended pulse width can be emitted.

[0034] By extending the pulse width of the laser beam, the generation of speckles on the surface of the semiconductor wafer exposed by the exposure apparatus 200 is suppressed. Speckles are bright and dark spots generated by interference when the laser beam is scattered to equalize the light intensity distribution of the laser beam. The intensity of the speckles is represented by the speckle contrast SC and can be calculated by the following formula. SC=(λ 2 / (A·Ω)+τ c / TIS) 1 / 2 Here, λ is the wavelength, A is the area of the beam cross-section, Ω is the beam divergence angle, τ c is the coherence time, and TIS is the pulse width calculated by the following formula. TIS=([∫I(t)dt] 2 ) / (∫I(t) 2 dt) Here, t is time and I(t) is the light intensity at time t.

[0035] 1.4.4 Others The highly reflective mirrors 61 and 62 reflect the laser beams Bps1 and Bps2, respectively, toward the beam combiner COM. The beam combiner COM combines the laser beams Bps1 and Bps2 by bringing their optical paths closer together and emits the combined light.

[0036] The processor 130 controls the applied voltages of the first and second oscillators MO1 and MO2 generated by the pulse power supply 12 and the applied voltages of the first and second amplifiers PO1 and PO2 generated by the pulse power supply 22 so that the energy of one pulse of the seed light B1 and the energy of one pulse of the laser light B2 each become desired values. Further, the processor 130 transmits an oscillation trigger signal to the pulse power supplies 12 and 22 so that the repetition frequency of the combined light output from the beam combiner COM becomes a desired value.

[0037] In order to improve the processing speed of the semiconductor wafer in the exposure apparatus 200, it is required to increase the output energy of the laser apparatus 100. As methods for increasing the output energy of the laser apparatus 100, a method of increasing the repetition frequency and a method of increasing the energy per pulse are conceivable. However, if the repetition frequency is increased, the next discharge may occur before the discharge products between the discharge electrodes 11a and 11b and between the discharge electrodes 21a and 21b are removed after one discharge, resulting in unstable discharge. Alternatively, if the rotation speed of a fan (not shown) is increased to remove the discharge products in a short time, the power consumption increases. Also, when the repetition frequency is increased, the influence of the acoustic wave becomes large and the light quality deteriorates. On the other hand, if the energy per pulse is increased, the peak intensity becomes large, so the optical element is likely to deteriorate due to two-photon absorption.

[0038] Therefore, the processor 130 alternately transmits oscillation trigger signals to the pulse power supplies 12 of the first and second oscillators MO1 and MO2. If the repetition frequency of each oscillation trigger signal of the first and second oscillators MO1 and MO2 is set to 6 kHz, the repetition frequency of the combined light can be set to 12 kHz. According to the configuration of the comparative example, compared with the case where laser oscillation is performed at a repetition frequency of 12 kHz using one oscillator and one amplifier, the first and second oscillators MO1 and MO2 and the first and second amplifiers PO1 and PO2 each perform laser oscillation at a repetition frequency of 6 kHz, so the possibility of unstable discharge can be reduced. Also, according to the configuration of the comparative example, compared with the case where laser oscillation is performed at a repetition frequency of 6 kHz using one oscillator and one amplifier, the energy of the laser light per unit time increases without increasing the peak intensity of the laser light, so the deterioration of the optical element is suppressed.

[0039] 1.5 Problems of the Comparative Example In the comparative example, the first and second oscillators MO1 and MO2 and the first and second amplifiers PO1 and PO2 are required. Since each of the first and second oscillators MO1 and MO2 includes the laser chamber 10 and the narrowbanding module 14, there is a problem that the laser device 100 becomes expensive and the installation space becomes large.

[0040] 2. Laser Device 100a for Branching the First Amplified Light Bpoa 2.1 Configuration FIG. 3 schematically shows the configuration of the laser device 100a according to the first embodiment. The laser device 100a includes an oscillator MO, first and second amplifiers POa and POb, a first beam splitter BSa, a first delay optical system DOb, a beam combiner COM, a pulse stretcher PS, and a processor 130. Although FIG. 3 shows several high-reflection mirrors for changing the traveling direction of light, the traveling direction of light and the arrangement of the high-reflection mirrors are not limited to those shown.

[0041] The configurations of the oscillator MO, the first and second amplifiers POa and POb, the beam combiner COM, the pulse stretcher PS, and the processor 130 are the same as those of the first oscillator MO1, the first and second amplifiers PO1 and PO2, the beam combiner COM, the first pulse stretcher PS1, and the processor 130 in the comparative example, respectively.

[0042] The oscillator MO emits pulsed seed light Bmo. The first amplifier POa is disposed in the optical path of the seed light Bmo and amplifies the seed light Bmo to emit first amplified light Bpoa.

[0043] The first beam splitter BSa is disposed in the optical path of the first amplified light Bpoa and splits the first amplified light Bpoa into a first split light Bpoa1 and a second split light Bpoa2. The second split light Bpoa2 has less energy than the first split light Bpoa1. When the first split light Bpoa1 is the light transmitted through the first beam splitter BSa and the second split light Bpoa2 is the light reflected by the first beam splitter BSa, the transmittance of the first beam splitter BSa is desirably 80% or more and 96% or less.

[0044] The first delay optical system DOb is disposed in the optical path of the second split light Bpoa2, delays the second split light Bpoa2, and emits it as the second split light Bdob2. The first delay optical system DOb includes a delay optical path configured by a relay optical system including a plurality of concave mirrors. The configuration of the first delay optical system DOb will be described later with reference to FIG. 10. The second amplifier POb is disposed in the optical path of the delayed second split light Bdob2 and amplifies the second split light Bdob2 to emit second amplified light Bpob.

[0045] The beam combiner COM is disposed in a space including the optical paths of both the first split light Bpoa1 and the second amplified light Bpob. The beam combiner COM emits combined light Bpoa1 + Bpob obtained by coupling the optical paths of the first split light Bpoa1 and the second amplified light Bpob in proximity to each other. The configuration of the beam combiner COM will be described later with reference to FIGS. 11 and 12.

[0046] The pulse stretcher PS is disposed in the optical path of the combined light Bpoa1 + Bpob, stretches the pulse width of the combined light Bpoa1 + Bpob, and emits it as output light Bps. In addition to the pulse stretcher PS disposed in the optical path of the combined light Bpoa1 + Bpob, or instead of the pulse stretcher PS, pulse stretchers (not shown) may be respectively disposed in the optical path of the first split light Bpoa1 and the optical path of the second amplified light Bpob. However, by disposing the pulse stretcher PS in the optical path of the combined light Bpoa1 + Bpob, the number of stages and the optical path length of the pulse stretcher included in the laser device 100a can be reduced.

[0047] Beam splitters with higher transmittance than reflectance are respectively disposed in the optical paths of the first split light Bpoa1 and the second amplified light Bpob. First energy sensors Epoa and second energy sensors Epob are respectively disposed in the optical paths of the light reflected by those beam splitters.

[0048] 2.2 Operation FIG. 4 is a time chart showing the oscillation trigger signals and the pulse time waveforms of the laser lights of the respective parts of the laser device 100a according to the first embodiment. The horizontal axis of FIG. 4 indicates time, and the vertical broken lines in FIG. 4 indicate that the events on the same broken line occur almost simultaneously.

[0049] 2.2.1 Timing Control The processor 130 outputs oscillation trigger signals Tmo, Tpoa, and Tpob to the oscillator MO and the first and second amplifiers POa and POb, respectively. The oscillator MO and the first and second amplifiers POa and POb emit the seed light Bmo and the first and second amplified lights Bpoa and Bpob, respectively, in response to the oscillation trigger signals Tmo, Tpoa, and Tpob.

[0050] The time from when the processor 130 outputs the oscillation trigger signal Tmo to the oscillator MO until it outputs the oscillation trigger signal Tpoa to the first amplifier POa is set such that parameters such as the energy, energy stability, and spectral linewidth of the first amplified light Bpoa are optimized.

[0051] The ratio of the energies of the first and second split lights Bpoa1 and Bpoa2 is determined by the transmittance of the first beam splitter BSa.

[0052] The delay time T1 of the delayed second split light Bdob2 with respect to the second split light Bpoa2 is determined by the optical path length of the delay optical path of the first delay optical system DOb. The time from when the processor 130 outputs the oscillation trigger signal Tpoa to the first amplifier POa until it outputs the oscillation trigger signal Tpob to the second amplifier POb is set such that parameters such as the energy, energy stability, and spectral linewidth of the second amplified light Bpob are optimized, and it becomes longer as the delay time T1 becomes longer.

[0053] The pulse time waveform of the output light Bps output from the pulse stretcher PS corresponds to the composite waveform of the pulse time waveform Wa of the extended first split light Bpoa1 when the pulse stretcher PS extends the pulse width of the first split light Bpoa1 and the pulse time waveform Wb of the extended second amplified light Bpob when the pulse stretcher PS extends the pulse width of the second amplified light Bpob.

[0054] The delay time T1 of the delayed second split light Bdob2 by the first delay optical system DOb is desirably 60% or more and 120% or less of the pulse width T2 of the pulse time waveform Wa. If the pulse width T2 is, for example, 500 ns, the desirable range of the delay time T1 is 300 ns or more and 600 ns or less. Furthermore, the speed of light is 3.0×10 8Since it is m / s, the desirable range of the optical path length of the delay optical path of the first delay optical system DOb is 90 m or more and 180 m or less. If the first delay optical system DOb is composed of, for example, 60 concave mirrors and the distance between adjacent concave mirrors on the optical path is 2.5 m, the optical path length of the delay optical path can be 150 m and the delay time T1 can be 500 ns.

[0055] The pulse time waveform Wa may include a plurality of peaks. The time interval T3 between adjacent peaks may correspond to the time for light to make one round in the delay optical path included in the pulse stretcher PS. Since the optical path length of the first delay optical system DOb is longer than the optical path length of the pulse stretcher PS, the delay time T1 is longer than the time interval T3. It is preferable that the optical path length of the first delay optical system DOb is two times or more the optical path length of the pulse stretcher PS. When the pulse stretcher PS has a configuration in which a plurality of stages of delay optical paths are connected in series, since the combinations of the number of round trips of each delay optical path become diverse, the pulse time waveform Wa becomes a complex waveform including more peaks. The same applies to the pulse time waveform Wb.

[0056] 2.2.2 Energy Control The energy of the seed light Bmo is measured by an energy sensor (not shown), and based on the measurement result, the processor 130 controls the applied voltage HVmo of the oscillator MO. Thereby, the energy of the seed light Bmo is controlled to be within an appropriate range as the seed light of the first amplifier POa.

[0057] In the first delay optical system DOb, the second split light Bpoa2 is attenuated each time it is reflected by a plurality of concave mirrors. Therefore, the energy of the delayed second split light Bdob2 emitted from the first delay optical system DOb is smaller than the energy of the second split light Bpoa2 incident on the first delay optical system DOb. When the energy of the seed light of the second amplifier POb is made equal to the seed light Bmo of the first amplifier POa, the energy of the second split light Bpoa2 incident on the first delay optical system DOb is larger than the energy of the seed light Bmo.

[0058] For example, when the reflectance of one concave mirror is 99% and the second split light Bpoa2 is incident on a delay optical path composed of 60 concave mirrors, the energy of the delayed second split light Bdob2 is attenuated to the 60th power of 99%, that is, 54.7%. For example, as the seed light of the second amplifier POb, energy of 0.5 mJ or more is required. When the energy of one pulse of the first amplified light Bpoa is, for example, 10 mJ, if the transmittance of the first beam splitter BSa is 90%, sufficient second split light Bdob2 can be obtained as the seed light of the second amplifier POb. When the number of concave mirrors is further increased beyond 60, for example, by making the transmittance of the first beam splitter BSa lower than 90%, it is possible to suppress the energy of the second split light Bdob2 from becoming insufficient.

[0059] The pulse time waveform of the combined light Bpoa1 + Bpob corresponds to the composite waveform of the first split light Bpoa1 and the second amplified light Bpob, and is controlled as follows. The energy of the first split light Bpoa1 and the energy of the second amplified light Bpob are measured by the first and second energy sensors Epoa and Epob, respectively. The processor 130 controls the applied voltage HVpoa of the first amplifier POa based on the measurement result by the first energy sensor Epoa, and controls the applied voltage HVpob of the second amplifier POb based on the measurement result by the second energy sensor Epob. The control of the applied voltage based on the measurement result of the energy will be described later with reference to FIG. 9.

[0060] Alternatively, the pulse time waveform of the combined light Bpoa1 + Bpob may be measured by an energy sensor (not shown), and the processor 130 may calculate the energy of the first portion corresponding to the first split light Bpoa1 and the energy of the second portion corresponding to the second amplified light Bpob in the pulse time waveform of the combined light Bpoa1 + Bpob. Further, the pulse time waveform of the output light Bps may be measured by an energy sensor (not shown), and the processor 130 may calculate the energy of the first portion corresponding to a part of the pulse time waveform Wa and the energy of the second portion corresponding to a part of the pulse time waveform Wb in the pulse time waveform of the output light Bps. In either case, the processor 130 may control the applied voltage HVpoa of the first amplifier POa based on the energy of the first portion and control the applied voltage HVpob of the second amplifier POb based on the energy of the second portion.

[0061] The first split light Bpoa1 and the second amplified light Bpob may have equivalent energy. Thus, the energy difference between the first split light Bpoa1 and the second amplified light Bpob may be smaller than the energy difference between the first and second split lights Bpoa1 and Bpoa2. Also, since the first split light Bpoa1 is generated by branching from the first amplified light Bpoa, the energy of the first amplified light Bpoa may be greater than the energy of the second amplified light Bpob.

[0062] 2.3 Operation (1) According to the first embodiment, the laser device 100a includes the following components. (a) An oscillator MO that emits pulsed seed light Bmo, (b) A first amplifier POa that amplifies the seed light Bmo and emits the first amplified light Bpoa, (c) A first beam splitter BSa that splits the first amplified light Bpoa into a first split light Bpoa1 and a second split light Bpoa2 having less energy than the first split light Bpoa1, (d) A first delay optical system DOb that delays the second split light Bpoa2, (e) A second amplifier POb that amplifies the delayed second split light Bdob2 and emits the second amplified light Bpob; (f) A beam combiner COM that combines the first split light Bpoa1 and the second amplified light Bpob and emits the combined light Bpoa1 + Bpob; (g) A pulse stretcher PS that stretches the pulse width of the combined light Bpoa1 + Bpob.

[0063] When the seed light Bmo output from the oscillator MO is split and incident on two amplifiers, in order to make the split seed light Bmo have the required amount of light in each of the two amplifiers, it is necessary to double the output energy of the oscillator MO, and the life of the oscillator MO may be shortened. According to the first embodiment, since the first amplified light Bpoa is split at a stage subsequent to the first amplifier POa, even if there is one oscillator MO and there is light attenuation in the first delay optical system DOb, it is possible to obtain the second split light Bdob2 with a sufficient amount of light as the seed light of the second amplifier POb while suppressing the load on the oscillator MO. Since there is one oscillator MO, and the laser chamber 10 and the narrowbanding module 14 may each be one, it is possible to suppress the laser device 100 from becoming expensive or the installation space from becoming large. Further, since the pulse stretcher PS is provided at a stage subsequent to the beam combiner COM, the number of pulse stretchers can be reduced as compared with the case where a pulse stretcher is provided in each of the optical paths of the first split light Bpoa1 and the second amplified light Bpob.

[0064] (2) According to the first embodiment, the delay time T1 of the second split light Bdob2 by the first delay optical system DOb is 60% or more and 120% or less of the pulse width T2 of the stretched first split light Bpoa1 when the pulse width of the first split light Bpoa1 is stretched by the pulse stretcher PS.

[0065] According to this, by setting the delay time T1 to 60% or more of the pulse width T2, the overlap of the pulse time waveforms Wa and Wb can be reduced and the pulse width of the output light Bps can be increased, and by setting it to 120% or less, the optical path length of the first delay optical system DOb can be suppressed and light attenuation can be suppressed.

[0066] (3) According to the first embodiment, the optical path length of the first delay optical system DOb is 90 m or more and 180 m or less.

[0067] According to this, by setting the optical path length to 90 m or more, the time difference between the first split light Bpoa1 and the second amplified light Bpob can be increased, and the pulse width of the output light Bps can be increased. By setting it to 180 m or less, the attenuation of light in the first delay optical system DOb can be suppressed.

[0068] (4) According to the first embodiment, the optical path length of the first delay optical system DOb is longer than the optical path length of the pulse stretcher PS.

[0069] According to this, the time difference due to the difference in the number of round trips of the delay optical path of the pulse stretcher PS is shorter than the time difference between the first split light Bpoa1 and the second amplified light Bpob incident on the beam combiner COM. Therefore, light with different numbers of round trips in the delay optical path of the pulse stretcher PS is output from the pulse stretcher PS at time intervals shorter than the time difference between the first split light Bpoa1 and the second amplified light Bpob. For this reason, the pulse width of the output light Bps output from the pulse stretcher PS can be increased.

[0070] (5) According to the first embodiment, the energy of the second split light Bpoa2 incident on the first delay optical system DOb is larger than the energy of the seed light Bmo.

[0071] According to this, since the energy of the second split light Bpoa2 is large, the second split light Bdob2 attenuated by the first delay optical system DOb can have a sufficient light amount as the seed light of the second amplifier POb.

[0072] (6) According to the first embodiment, the laser device 100a includes a first energy sensor Epoa that measures the energy of the first split light Bpoa1, a second energy sensor Epob that measures the energy of the second amplified light Bpob, and a processor 130. The processor 130 controls the applied voltage HVpoa of the first amplifier POa based on the measurement result by the first energy sensor Epoa, and controls the applied voltage HVpob of the second amplifier POb based on the measurement result by the second energy sensor Epob.

[0073] According to this, by separately measuring the first split light Bpoa1 and the second amplified light Bpob, and independently controlling the applied voltages HVpoa and HVpob of the first and second amplifiers POa and POb, the pulse time waveform of the combined light Bpoa1 + Bpob can be accurately controlled, and sufficient energy stability can be achieved. Also, the dose amount indicating the energy of the laser light irradiated on one location of the semiconductor wafer can be stabilized.

[0074] (7) According to the first embodiment, the energy of the first amplified light Bpoa is greater than the energy of the second amplified light Bpob.

[0075] According to this, since the energy of the first amplified light Bpoa is large, the first split light Bpoa1 obtained by splitting the first amplified light Bpoa can have a sufficient light amount as a part of the combined light Bpoa1 + Bpob.

[0076] (8) According to the first embodiment, the first split light Bpoa1 is the light transmitted through the first beam splitter BSa, the second split light Bpoa2 is the light reflected by the first beam splitter BSa, and the transmittance of the first beam splitter BSa is 80% or more and 96% or less.

[0077] According to this, the first split light Bpoa1 can have a sufficient light amount as a part of the combined light Bpoa1 + Bpob, and the second split light Bdob2 obtained by delaying the second split light Bpoa2 with the first delay optical system DOb can have a sufficient light amount as the seed light of the second amplifier POb.

[0078] (9) According to the first embodiment, the first delay optical system DOb includes a relay optical system including a plurality of concave mirrors 41 to 46 (see FIG. 10).

[0079] According to this, it is possible to suppress a change in the optical quality in the first delay optical system DOb.

[0080] (10) According to the first embodiment, the beam combiner COM combines the optical paths of the first split light Bpoa1 and the second amplified light Bpob to emit combined light Bpoa1 + Bpob.

[0081] According to this, even if the wavelengths and polarization directions of the first split light Bpoa1 and the second amplified light Bpob are the same, combined light Bpoa1 + Bpob can be generated.

[0082] In other respects, the first embodiment is the same as the comparative example.

[0083] 3. Laser device 100b that further branches the second amplified light Bpob 3.1 Configuration FIG. 5 schematically shows the configuration of the laser device 100b according to the second embodiment. The laser device 100b includes a second beam splitter BSb, a second delay optical system DOc, and a third amplifier POc. The configurations of the second beam splitter BSb, the second delay optical system DOc, and the third amplifier POc are the same as those of the first beam splitter BSa, the first delay optical system DOb, and the second amplifier POb in the first embodiment, respectively.

[0084] The second beam splitter BSb is disposed in the optical path of the second amplified light Bpob, and splits the second amplified light Bpob into a third split light Bpob3 and a fourth split light Bpob4. The fourth split light Bpob4 has less energy than the third split light Bpob3. When the third split light Bpob3 is the light transmitted through the second beam splitter BSb and the fourth split light Bpob4 is the light reflected by the second beam splitter BSb, it is desirable that the transmittance of the second beam splitter BSb be 80% or more and 96% or less.

[0085] The second delay optical system DOc is disposed in the optical path of the fourth split light Bpob4, delays the fourth split light Bpob4, and emits it as the fourth split light Bdoc4. The third amplifier POc is disposed in the optical path of the delayed fourth split light Bdoc4, amplifies the fourth split light Bdoc4, and emits the third amplified light Bpoc.

[0086] The beam combiner COM is disposed in a space including the optical paths of the first split light Bpoa1, the third split light Ppob3, and the third amplified light Bpoc. The beam combiner COM emits combined light Bpoa1 + Bpob3 + Bpoc obtained by combining the optical paths of the first split light Bpoa1, the third split light Ppob3 which is a part of the second amplified light Bpob, and the third amplified light Bpoc in proximity. The configuration of the beam combiner COM will be described later with reference to FIG. 13.

[0087] The pulse stretcher PS is disposed in the optical path of the combined light Bpoa1 + Bpob3 + Bpoc, stretches the pulse width of the combined light Bpoa1 + Bpob3 + Bpoc, and emits it as output light Bps. In addition to the pulse stretcher PS disposed in the optical path of the combined light Bpoa1 + Bpob3 + Bpoc, or instead of the pulse stretcher PS, pulse stretchers (not shown) may be disposed in the optical paths of the first split light Bpoa1, the third split light Ppob3, and the third amplified light Bpoc, respectively.

[0088] In the optical paths of the first split light Bpoa1, the third split light Bpob3, and the third amplified light Bpoc, beam splitters with higher transmittance than reflectance are respectively arranged. In the optical paths of the light reflected by these beam splitters, a first energy sensor Epoa, a second energy sensor Epob, and a third energy sensor Epoc are respectively arranged.

[0089] 3.2 Operation FIG. 6 is a time chart showing the pulse time waveforms of the laser light of each part of the laser device 100b according to the second embodiment.

[0090] 3.2.1 Timing Control The optical path lengths of the delay optical paths of the first and second delay optical systems DOb and Doc may be substantially the same, and the time difference between the first split light Bpoa1 and the third split light Bpob3 and the time difference between the third split light Bpob3 and the third amplified light Bpoc may be substantially the same.

[0091] The pulse time waveform of the output light Bps output from the pulse stretcher PS corresponds to the composite waveform of the pulse time waveforms Wa, Wb, and Wc when the pulse widths of the first split light Bpoa1, the third split light Bpob3, and the third amplified light Bpoc are respectively extended by the pulse stretcher PS.

[0092] The delay time of the fourth split light Bdoc4 delayed by the second delay optical system Doc is desirably 60% or more and 120% or less of the pulse width of the pulse time waveform Wb.

[0093] 3.2.2 Energy Control The pulse time waveform of the combined light Bpoa1 + Bpob3 + Bpoc corresponds to the composite waveform of the first split light Bpoa1, the third split light Bpob3, and the third amplified light Bpoc, and is controlled as follows. The energy of the first split light Bpoa1, the energy of the third split light Bpob3, and the energy of the third amplified light Bpoc are measured by the first, second, and third energy sensors Epoa, Epob, and Epoc, respectively. The processor 130 controls the applied voltage HVpoa of the first amplifier POa based on the measurement result by the first energy sensor Epoa, controls the applied voltage HVpob of the second amplifier POb based on the measurement result by the second energy sensor Epob, and controls the applied voltage HVpoc of the third amplifier POc based on the measurement result by the third energy sensor Epoc.

[0094] Alternatively, the pulse time waveform of the combined light Bpoa1 + Bpob3 + Bpoc is measured by an energy sensor (not shown), and the processor 130 may calculate the energy of the first portion corresponding to the first split light Bpoa1 in the pulse time waveform of the combined light Bpoa1 + Bpob3 + Bpoc, the energy of the second portion corresponding to the third split light Bpob3, and the energy of the third portion corresponding to the third amplified light Bpoc. Also, the pulse time waveform of the output light Bps is measured by an energy sensor (not shown), and the processor 130 may calculate the energy of the first portion corresponding to a part of the pulse time waveform Wa in the pulse time waveform of the output light Bps, the energy of the second portion corresponding to a part of the pulse time waveform Wb, and the energy of the third portion corresponding to a part of the pulse time waveform Wc. In either case, the processor 130 may control the applied voltage HVpoa of the first amplifier POa based on the energy of the first portion, control the applied voltage HVpob of the second amplifier POb based on the energy of the second portion, and control the applied voltage HVpoc of the third amplifier POc based on the energy of the third portion.

[0095] The first split light Bpoa1, the third split light Bpob3, and the third amplified light Bpoc may have the same energy. Since the first split light Bpoa1 is generated by branching from the first amplified light Bpoa and the third split light Bpob3 is generated by branching from the second amplified light Bpob, the energy of each of the first amplified light Bpoa and the second amplified light Bpob may be greater than the energy of any of the first split light Bpoa1, the third split light Bpob3, and the third amplified light Bpoc. Also, the energy difference between the third split light Bpob3 and the third amplified light Bpoc may be smaller than the energy difference between the third and fourth split lights Bpob3 and Bpob4.

[0096] 3.3 Operation (11) According to the second embodiment, the laser device 100b includes the following components in addition to the components of the laser device 100a. (h) A second beam splitter BSb that splits the second amplified light Bpob into a third split light Bpob3 and a fourth split light Bpob4 having less energy than the third split light Bpob3. (i) A second delay optical system DOc that delays the fourth split light Bpob4. (j) A third amplifier POc that amplifies the delayed fourth split light Bdoc4 and emits the third amplified light Bpoc.

[0097] In the second embodiment, the beam combiner COM combines the first split light Bpoa1, the third split light Bpob3 which is a part of the second amplified light Bpob, and the third amplified light Bpoc, and emits a combined light Bpoa1 + Bpob3 + Bpoc.

[0098] According to this, by combining the first split light Bpoa1, the third split light Bpob3, and the third amplified light Bpoc with mutually shifted timings, and extending the pulse width of the combined light Bpoa1 + Bpob3 + Bpoc, the pulse width can be made even larger. And since the second amplified light Bpob is split at a stage subsequent to the second amplifier POb, beam characteristics other than the emission timings of the third and fourth split lights Bpob3 and Bpob4 can be made equivalent to those of the first and second split lights Bpoa1 and Bpoa2, respectively. For this reason, the first and second delay optical systems DOb and DOc can be made to have equivalent specifications to each other, and the second and third amplifiers POb and POc can be made to have equivalent specifications to each other.

[0099] (12) According to the second embodiment, the laser device 100b includes a first energy sensor Epoa that measures the energy of the first split light Bpoa1, a second energy sensor Epob that measures the energy of the third split light Bpob3, a third energy sensor Epoc that measures the energy of the third amplified light Bpoc, and a processor 130. The processor 130 controls the applied voltage HVpoa of the first amplifier POa based on the measurement result by the first energy sensor Epoa, controls the applied voltage HVpob of the second amplifier POb based on the measurement result by the second energy sensor Epob, and controls the applied voltage HVpoc of the third amplifier POc based on the measurement result by the third energy sensor Epoc.

[0100] According to this, by separately measuring the first split light Bpoa1, the third split light Bpob3, and the third amplified light Bpoc, and independently controlling the applied voltages HVpoa, HVpob, and HVpoc of the first, second, and third amplifiers POa, POb, and POc, the pulse time waveform of the combined light Bpoa1 + Bpob3 + Bpoc can be accurately controlled.

[0101] (13) According to the second embodiment, the energy of each of the first amplified light Bpoa and the second amplified light Bpob is larger than the energy of the third amplified light Bpoc.

[0102] According to this, since the energy of each of the first amplified light Bpoa and the second amplified light Bpob is large, each of the first split light Bpoa1 and the third split light Bpob3 obtained by splitting the first amplified light Bpoa and the second amplified light Bpob can have a sufficient light quantity as a part of the combined light Bpoa1 + Bpob3 + Bpoc.

[0103] (14) According to the second embodiment, the third split light Bpob3 is the light transmitted through the second beam splitter BSb, the fourth split light Bpob4 is the light reflected by the second beam splitter BSb, and the transmittance of the second beam splitter BSb is 80% or more and 96% or less.

[0104] According to this, the third split light Bpob3 can have a sufficient light quantity as a part of the combined light Bpoa1 + Bpob3 + Bpoc, and the fourth split light Bdoc4 can have a sufficient light quantity as the seed light of the third amplifier POc.

[0105] In other respects, the second embodiment is the same as the first embodiment.

[0106] 4. Laser device 100c for further branching the second split light Bpoa2 4.1 Configuration FIG. 7 schematically shows the configuration of the laser device 100c according to the third embodiment. The laser device 100c includes a second beam splitter BSc, a second delay optical system DOc, and a third amplifier POc. The configurations of the second delay optical system DOc and the third amplifier POc are the same as those of the first delay optical system DOb and the second amplifier POb in the first embodiment, respectively.

[0107] The second beam splitter BSc is disposed in the optical path of the second split light Bpoa2 and splits the second split light Bpoa2 into a third split light Bpoa3 and a fourth split light Bpoa4. The third split light Bpoa3 is the light reflected by the second beam splitter BSc, and the fourth split light Bpoa4 is the light transmitted through the second beam splitter BSc. The first delay optical system DOb delays a part of the third split light Bpoa3, which is a part of the second split light Bpoa2, and the second amplifier POb amplifies the delayed third split light Bdob3 to emit a second amplified light Bpob.

[0108] The second delay optical system DOc is disposed in the optical path of the fourth split light Bpoa4, delays the fourth split light Bpoa4, and emits it as a fourth split light Bdoc4. The third amplifier POc is disposed in the optical path of the delayed fourth split light Bdoc4, amplifies the fourth split light Bdoc4, and emits a third amplified light Bpoc.

[0109] The optical path length of the delay optical path of the second delay optical system DOc is larger than that of the first delay optical system DOb. The optical path length of the delay optical path of the second delay optical system DOc may be approximately twice that of the first delay optical system DOb, and in the second delay optical system DOc, light is significantly attenuated more than in the first delay optical system DOb. In order to make the energy of the seed light of the third amplifier POc equivalent to that of the seed light of the second amplifier POb, the energy of the fourth split light Bpoa4 is made larger than the energy of the third split light Bpoa3. Therefore, it is desirable that the reflectance of the second beam splitter BSc be 20% or more and 40% or less.

[0110] In the first and second embodiments, the seed light of the second amplifier POb was obtained from the second split light Bpoa2 reflected by the first beam splitter BSa, whereas in the third embodiment, it is necessary to obtain the seed lights of both the second and third amplifiers POb and POc from the second split light Bpoa2 reflected by the first beam splitter BSa. Therefore, it is desirable that the transmittance of the first beam splitter BSa be 70% or more and 90% or less.

[0111] The beam combiner COM is arranged in a space including three optical paths of a first split light Bpoa1, a second amplified light Ppob, and a third amplified light Bpoc. The beam combiner COM emits a combined light Bpoa1 + Bpob + Bpoc obtained by combining the optical paths of the first split light Bpoa1, the second amplified light Bpob, and the third amplified light Bpoc in proximity to each other.

[0112] The pulse stretcher PS is arranged in the optical path of the combined light Bpoa1 + Bpob + Bpoc, stretches the pulse width of the combined light Bpoa1 + Bpob + Bpoc, and emits it as output light Bps. In addition to the pulse stretcher PS arranged in the optical path of the combined light Bpoa1 + Bpob + Bpoc, or instead of the pulse stretcher PS, pulse stretchers (not shown) may be arranged in the optical paths of the first split light Bpoa1, the second amplified light Ppob, and the third amplified light Bpoc, respectively.

[0113] In the optical paths of the first split light Bpoa1, the second amplified light Bpob, and the third amplified light Bpoc, beam splitters with higher transmittance than reflectance are arranged respectively. In the optical paths of the light reflected by those beam splitters, a first energy sensor Epoa, a second energy sensor Epob, and a third energy sensor Epoc are arranged respectively.

[0114] 4.2 Operation FIG. 8 is a time chart showing the pulse time waveforms of the laser light of each part of the laser device 100c according to the third embodiment.

[0115] 4.2.1 Timing Control The time difference between the first split light Bpoa1 and the second amplified light Bpob and the time difference between the second amplified light Bpob and the third amplified light Bpoc may be substantially the same.

[0116] The pulse time waveform of the output light Bps output from the pulse stretcher PS corresponds to the composite waveform of the pulse time waveforms Wa, Wb, and Wc when the pulse widths of the first divided light Bpoa1, the second amplified light Bpob, and the third amplified light Bpoc are respectively stretched by the pulse stretcher PS.

[0117] The delay time of the delayed fourth divided light Bdoc4 by the second delay optical system DOc is preferably 120% or more and 240% or less of the pulse width of the pulse time waveform Wa. The desirable range of the optical path length of the delay optical path of the second delay optical system DOc is 180 m or more and 360 m or less. Further, the optical path length of the second delay optical system DOc is longer than twice the optical path length of the pulse stretcher PS, and more preferably 4 times or more the optical path length of the pulse stretcher PS.

[0118] 4.2.2 Energy Control The pulse time waveform of the combined light Bpoa1 + Bpob + Bpoc corresponds to the composite waveform of the first divided light Bpoa1, the second amplified light Bpob, and the third amplified light Bpoc, and is controlled as follows. The energy of the first divided light Bpoa1, the energy of the second amplified light Bpob, and the energy of the third amplified light Bpoc are respectively measured by the first, second, and third energy sensors Epoa, Epob, and Epoc. The processor 130 controls the applied voltage HVpoa of the first amplifier POa based on the measurement result by the first energy sensor Epoa, controls the applied voltage HVpob of the second amplifier POb based on the measurement result by the second energy sensor Epob, and controls the applied voltage HVpoc of the third amplifier POc based on the measurement result by the third energy sensor Epoc.

[0119] Alternatively, the pulse time waveform of the combined light Bpoa1 + Bpob + Bpoc is measured by an energy sensor (not shown), and the processor 130 calculates, for example, the energy of the first part corresponding to the first split light Bpoa1 among the pulse time waveforms of the combined light Bpoa1 + Bpob + Bpoc, the energy of the second part corresponding to the second amplified light Bpob, and the energy of the third part corresponding to the third amplified light Bpoc. Further, the pulse time waveform of the output light Bps is measured by an energy sensor (not shown), and the processor 130 calculates the energy of the first part corresponding to a part of the pulse time waveform Wa among the pulse time waveforms of the output light Bps, the energy of the second part corresponding to a part of the pulse time waveform Wb, and the energy of the third part corresponding to a part of the pulse time waveform Wc. In any case, the processor 130 may control the applied voltage HVpoa of the first amplifier POa based on the energy of the first part, control the applied voltage HVpob of the second amplifier POb based on the energy of the second part, and control the applied voltage HVpoc of the third amplifier POc based on the energy of the third part.

[0120] The first split light Bpoa1, the second amplified light Bpob, and the third amplified light Bpoc may have equal energy. Since the first split light Bpoa1 is generated by branching from the first amplified light Bpoa, the energy of the first amplified light Bpoa may be greater than the energy of either the second amplified light Bpob or the third amplified light Bpoc.

[0121] 4.3 Operation (15) According to the third embodiment, the laser device 100c includes the following components in addition to the components of the laser device 100a. (h) A second beam splitter BSc that splits the second split light Bpoa2 into a third split light Bpoa3 and a fourth split light Bpoa4. (i) A second delay optical system DOc that delays the fourth split light Bpoa4. (j) A third amplifier POc that amplifies the delayed fourth split light Bdoc4 and emits the third amplified light Bpoc.

[0122] In the third embodiment, the first delay optical system DOb delays the third split light Bpoa3 which is a part of the second split light Bpoa2. The second amplifier POb amplifies the delayed third split light Bdob3 and emits the second amplified light Bpob. The beam combiner COM combines the first split light Bpoa1, the second amplified light Bpob, and the third amplified light Bpoc, and emits the combined light Bpoa1 + Bpob + Bpoc.

[0123] According to this, by combining the first split light Bpoa1, the second amplified light Bpob, and the third amplified light Bpoc with mutually shifted timings, and extending the pulse width of the combined light Bpoa1 + Bpob + Bpoc, the pulse width can be made even larger. And since the second split light Bpoa2 is split after the first amplifier POa, even if there is one oscillator MO and there is attenuation of the light amount in the first and second delay optical systems DOb and DOc, sufficient light amounts of the third and fourth split lights Bdob3 and Bdoc4 can be obtained as the seed light for the second and third amplifiers POb and POc while suppressing the load on the oscillator MO.

[0124] (16) According to the third embodiment, the optical path length of the second delay optical system DOc is larger than the optical path length of the first delay optical system DOb.

[0125] According to this, since the optical path lengths of the first and second delay optical systems DOb and DOc are different, the timings of the second and third amplified lights Bpob and Bpoc can be shifted from each other.

[0126] (17) According to the third embodiment, the third split light Bpoa3 is the light reflected by the second beam splitter BSc, the fourth split light Bpoa4 is the light transmitted through the second beam splitter BSc, and the reflectance of the second beam splitter BSc is 20% or more and 40% or less.

[0127] According to this, by making the energy of the fourth split light Bpoa4 larger than that of the third split light Bpoa3, even if the attenuation in the second delay optical system DOc is larger than the attenuation in the first delay optical system DOb, the fourth split light Bdoc4 can have a sufficient light amount as the seed light of the third amplifier POc.

[0128] (18) According to the third embodiment, the first split light Bpoa1 is the light transmitted through the first beam splitter BSa, the second split light Bpoa2 is the light reflected by the first beam splitter BSa, and the transmittance of the first beam splitter BSa is 70% or more and 90% or less.

[0129] According to this, the third and fourth split lights Bdob3 and Bdoc4 can have a sufficient light amount as the seed lights of the second and third amplifiers POb and POc.

[0130] (19) According to the third embodiment, the laser device 100c includes a first energy sensor Epoa that measures the energy of the first split light Bpoa1, a second energy sensor Epob that measures the energy of the second amplified light Bpob, a third energy sensor Epoc that measures the energy of the third amplified light Bpoc, and a processor 130. The processor 130 controls the applied voltage HVpoa of the first amplifier POa based on the measurement result by the first energy sensor Epoa, controls the applied voltage HVpob of the second amplifier POb based on the measurement result by the second energy sensor Epob, and controls the applied voltage HVpoc of the third amplifier POc based on the measurement result by the third energy sensor Epoc.

[0131] According to this, by separately measuring the first split light Bpoa1, the second amplified light Bpob, and the third amplified light Bpoc, and independently controlling the applied voltages HVpoa, HVpob, and HVpoc of the first, second, and third amplifiers POa, POb, and POc, the pulse time waveform of the combined light Bpoa1 + Bpob + Bpoc can be accurately controlled.

[0132] Regarding other points, the third embodiment is the same as the first embodiment.

[0133] 5. Others 5.1 Control of applied voltage FIG. 9 is a flowchart of the control of the applied voltage executed by the processor 130 in the first to third embodiments. In FIG. 9, the following seven controls are collectively described as the control of the applied voltage HV based on the energy E of the laser beam. (a) Control of the applied voltage HVmo of the oscillator MO based on the energy of the seed light Bmo measured by an energy sensor (not shown) (b) Control of the applied voltage HVpoa of the first amplifier POa based on the energy of the first split light Bpoa1 measured by the first energy sensor Epoa (c) Control of the applied voltage HVpob of the second amplifier POb based on the energy of the second amplified light Bpob or the third split light Bpob3 measured by the second energy sensor Epob (d) Control of the applied voltage HVpoc of the third amplifier POc based on the energy of the third amplified light Bpoc measured by the third energy sensor Epoc (e) Control of the applied voltage HVpoa of the first amplifier POa based on the energy of the output light Bps, the combined light Bpoa1 + Bpob, the combined light Bpoa1 + Bpob3 + Bpoc, or the first part of the combined light Bpoa1 + Bpob + Bpoc measured by an energy sensor (not shown) (f) Control of the applied voltage HVpob of the second amplifier POb based on the energy of the output light Bps, the combined light Bpoa1 + Bpob, the combined light Bpoa1 + Bpob3 + Bpoc, or the second part of the combined light Bpoa1 + Bpob + Bpoc measured by an energy sensor (not shown) (g) Control of the applied voltage HVpoc of the third amplifier POc based on the energy of the output light Bps, the combined light Bpoa1 + Bpob3 + Bpoc, or the third part of the combined light Bpoa1 + Bpob + Bpoc measured by an energy sensor (not shown)

[0134] In S1, the processor 130 obtains the result of measuring the energy E of the laser light while changing the applied voltage HV, and calculates the slope k of the energy E with respect to the applied voltage HV. This calculation is performed at regular intervals.

[0135] In S2, the processor 130 outputs an oscillation trigger signal to output one pulse of laser light.

[0136] In S3, the processor 130 obtains the measurement result of the energy E of the laser light and calculates the difference ΔE from the target value.

[0137] In S4, the processor 130 calculates the correction amount ΔHV of the applied voltage HV by the following formula. ΔHV = ΔE / k

[0138] In S5, the processor 130 corrects the applied voltage HV of the next pulse using the correction amount ΔHV.

[0139] After S5, the processor 130 returns the process to S2. In this way, the applied voltage HV is controlled so that the energy E of the laser light approaches the target value.

[0140] 5.2 Configuration of the Delay Optical System FIG. 10 shows a configuration example of a first delay optical system DOb used in the first and second embodiments. The first delay optical system DOb includes a plurality of concave mirrors 41 to 46. The concave mirrors 41 to 46 are arranged to reflect the second split light Bpoa2 in ascending order of their numbers. By arranging the distance L between adjacent mirrors on the optical path to be equal to the radius of curvature R of each of the concave mirrors 41 to 46, a relay optical system is configured. The value obtained by multiplying the number of concave mirrors by the distance L becomes the optical path length of the first delay optical system DOb.

[0141] The first delay optical system DOb shown in FIG. 10 can also be used in the third embodiment. In that case, instead of the second split light Bpoa2, the third split light Bpoa3 is incident on the concave mirrors 41 to 46. The second delay optical system DOc used in the second and third embodiments may be the same as the first delay optical system DOb.

[0142] 5.3 Configuration of Beam Combiner COM FIG. 11 shows a first configuration example of the beam combiner COM used in the first embodiment. The beam combiner COM according to the first configuration example includes a prism mirror 51 coated with a high reflection film 511.

[0143] The first split light Bpoa1 and the second amplified light Bpob enter the beam combiner COM through optical paths perpendicular to each other. The high reflection surface coated with the high reflection film 511 is inclined at 45 degrees with respect to both the first split light Bpoa1 and the second amplified light Bpob. The high reflection surface of the prism mirror 51 and another surface form a ridge line 510 at an angle of 45 degrees or less. The second amplified light Bpob does not enter the prism mirror 51 and passes through a position as close as possible to the ridge line 510 of the prism mirror 51. The first split light Bpoa1 is incident on a position as close as possible to the ridge line 510 of the high reflection surface and is reflected in a direction parallel to the second amplified light Bpob. Thereby, the first split light Bpoa1 and the second amplified light Bpob can be brought close to each other.

[0144] FIG. 12 shows a second configuration example of the beam combiner COM used in the first embodiment. The beam combiner COM according to the second configuration example has a configuration in which a high reflection film 521 is coated on a part of a plane substrate 52 that is transparent to the second amplified light Bpob, and a reflection suppression film is coated on another part.

[0145] The first split light Bpoa1 and the second amplified light Bpob enter the planar substrate 52 through optical paths perpendicular to each other. The highly reflective surface coated with the high-reflection film 521 is inclined at 45 degrees with respect to both the first split light Bpoa1 and the second amplified light Bpob. The second amplified light Bpob passes through a position as close as possible to the boundary between the portion coated with the reflection suppression film and the portion coated with the high-reflection film 521. The first split light Bpoa1 is incident on a position as close as possible to the boundary between the portion coated with the high-reflection film 521 and the portion coated with the reflection suppression film, and is reflected in a direction parallel to the second amplified light Bpob. Thereby, the first split light Bpoa1 and the second amplified light Bpob can be brought close to each other.

[0146] FIG. 13 shows a third configuration example of the beam combiner COM used in the second embodiment. The beam combiner COM according to the third configuration example includes a prism mirror 53 coated with a high-reflection film 531 and a prism mirror 54 coated with a high-reflection film 541.

[0147] The first split light Bpoa1 and the third amplified light Bpoc enter the beam combiner COM through optical paths in opposite directions, and the third split light Bpob3 enters the beam combiner COM through an optical path perpendicular to both the first split light Bpoa1 and the third amplified light Bpoc. The highly reflective surface coated with the high-reflection film 531 and the highly reflective surface coated with the high-reflection film 541 are inclined at 45 degrees with respect to any of the first split light Bpoa1, the third split light Bpob3, and the third amplified light Bpoc.

[0148] The highly reflective surface of the prism mirror 53 and another surface form a ridge line 530 at an angle of 45 degrees or less, and the highly reflective surface of the prism mirror 54 and another surface form a ridge line 540 at an angle of 45 degrees or less. The distance between the ridge line 530 and the ridge line 540 is approximately equal to the beam width of the third split light Bpob3.

[0149] The third split light Bpob3 does not enter either of the prism mirrors 53 and 54, and passes between the ridge lines 530 and 540 of the prism mirrors 53 and 54. The first split light Bpoa1 is incident on a position as close as possible to the ridge line 530 among the highly reflective surfaces of the prism mirror 53, and is reflected in a direction parallel to the third split light Bpob3. The third amplified light Bpoc is incident on a position as close as possible to the ridge line 540 among the highly reflective surfaces of the prism mirror 54, and is reflected in a direction parallel to the third split light Bpob3. Thereby, the first split light Bpoa1, the third split light Bpob3, and the third amplified light Bpoc can be brought close to each other.

[0150] The beam combiner COM shown in FIG. 13 can also be used in the third embodiment. In that case, instead of the third split light Bpob3, the second amplified light Bpob passes between the ridge lines 530 and 540.

[0151] In the second and third embodiments, three beams may be brought close to each other by combining two beam combiners COM shown in FIG. 11 or FIG. 12.

[0152] 5.4 Supplementary The above description is intended to be illustrative, not restrictive. Thus, it is apparent to those skilled in the art that modifications can be made to the embodiments of the present disclosure without departing from the scope of the claims. It is also apparent to those skilled in the art that the embodiments of the present disclosure can be used in combination.

[0153] The terms used throughout this specification and the claims should be construed as "non-limiting" terms unless otherwise specified. For example, terms such as "comprising", "having", "including", and "containing" should be construed as not excluding the presence of elements other than those described. Also, the modifier "one" should be construed to mean "at least one" or "one or more". Further, 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". Moreover, it should be construed to include combinations with things other than "A", "B", and "C".

Claims

1. An oscillator that emits pulsed seed light, A first amplifier that amplifies the seed light and emits first amplified light, A first beam splitter that splits the first amplified light into a first split light and a second split light having less energy than the first split light, A first delay optical system that delays the second split light, A second amplifier that amplifies the delayed second split light and emits second amplified light, A beam combiner that emits combined light obtained by combining the first split light and the second amplified light, A pulse stretcher that stretches the pulse width of the combined light, A laser device comprising the above.

2. The laser device according to Claim 1, wherein the delay time of the second split light by the first delay optical system is 60% or more and 120% or less of the pulse width of the stretched first split light when the first split light is stretched by the pulse stretcher. Laser device.

3. The laser device according to Claim 1, wherein the optical path length of the first delay optical system is 90 m or more and 180 m or less. Laser device.

4. The laser device according to Claim 1, wherein the optical path length of the first delay optical system is longer than the optical path length of the pulse stretcher. Laser device.

5. The laser device according to Claim 1, wherein the energy of the second split light incident on the first delay optical system is greater than the energy of the seed light. Laser device.

6. The laser device according to Claim 1, further comprising a first energy sensor that measures the energy of the first split light, a second energy sensor that measures the energy of the second amplified light, and a processor, wherein the processor controls the applied voltage of the first amplifier based on the measurement result by the first energy sensor and controls the applied voltage of the second amplifier based on the measurement result by the second energy sensor. Laser device.

7. The laser device according to Claim 1, wherein the energy of the first amplified light is greater than the energy of the second amplified light. Laser device.

8. The laser device according to Claim 1, wherein the first split light is the light transmitted through the first beam splitter, the second split light is the light reflected by the first beam splitter, and the transmittance of the first beam splitter is 80% or more and 96% or less. Laser device.

9. The laser device according to Claim 1, ​ The first delay optical system includes a relay optical system including a plurality of concave mirrors laser device.

10. The laser device according to claim 1, The beam combiner combines the optical paths of the first split light and the second amplified light to emit the combined light laser device.

11. The laser device according to claim 1, A second beam splitter that splits the second amplified light into a third split light and a fourth split light having less energy than the third split light; A second delay optical system that delays the fourth split light; A third amplifier that amplifies the delayed fourth split light to emit a third amplified light; further comprising The beam combiner combines the first split light, the third split light which is a part of the second amplified light, and the third amplified light to emit the combined light. laser device.

12. The laser device according to claim 11, A first energy sensor that measures the energy of the first split light; A second energy sensor that measures the energy of the third split light; A third energy sensor that measures the energy of the third amplified light; A processor; further comprising The processor controls the applied voltage of the first amplifier based on the measurement result of the first energy sensor, controls the applied voltage of the second amplifier based on the measurement result of the second energy sensor, and controls the applied voltage of the third amplifier based on the measurement result of the third energy sensor. laser device.

13. The laser device according to claim 11, The energy of each of the first amplified light and the second amplified light is greater than the energy of the third amplified light laser device.

14. The laser device according to claim 11, The third split light is the light transmitted through the second beam splitter, The fourth split light is the light reflected by the second beam splitter, The transmittance of the second beam splitter is 80% or more and 96% or less. laser device.

15. The laser device according to claim 1, A second beam splitter that splits the second split light into a third split light and a fourth split light; A second delay optical system that delays the fourth split light; A third amplifier that amplifies the delayed fourth split light to emit a third amplified light; further comprising The first delay optical system delays the third split light, which is a part of the second split light, The second amplifier amplifies the delayed third split light and emits the second amplified light, The beam combiner combines the first split light, the second amplified light, and the third amplified light and emits the combined light, Laser device.

16. The laser device according to claim 15, wherein the optical path length of the second delay optical system is greater than the optical path length of the first delay optical system Laser device.

17. The laser device according to claim 15, wherein the third split light is the light reflected by the second beam splitter, the fourth split light is the light transmitted through the second beam splitter, and the reflectivity of the second beam splitter is 20% or more and 40% or less. Laser device.

18. The laser device according to claim 15, wherein the first split light is the light transmitted through the first beam splitter, the second split light is the light reflected by the first beam splitter, and the transmittance of the first beam splitter is 70% or more and 90% or less. Laser device.

19. The laser device according to claim 15, further comprising a first energy sensor that measures the energy of the first split light, a second energy sensor that measures the energy of the second amplified light, a third energy sensor that measures the energy of the third amplified light, and a processor, wherein the processor controls the applied voltage of the first amplifier based on the measurement result of the first energy sensor, controls the applied voltage of the second amplifier based on the measurement result of the second energy sensor, and controls the applied voltage of the third amplifier based on the measurement result of the third energy sensor. Laser device.

20. A method for manufacturing an electronic device, comprising: an oscillator that emits pulsed seed light, a first amplifier that amplifies the seed light and emits first amplified light, a first beam splitter that splits the first amplified light into a first split light and a second split light having less energy than the first split light, a first delay optical system that delays the second split light, a second amplifier that amplifies the delayed second split light and emits second amplified light, and a beam combiner that emits combined light obtained by combining the first split light and the second amplified light. ​ A pulse stretcher that stretches the pulse width of the combined light, generates laser light by a laser device including, outputs the laser light to an exposure device, and exposes the laser light on a photosensitive substrate in the exposure device in order to manufacture the electronic device. A method for manufacturing an electronic device including this.

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