Laser device and method for manufacturing electronic device

Abstract

The laser device comprises: a first actuator for adjusting the oscillation wavelength of a pulsed laser; a second actuator for adjusting the spectral line width of the pulsed laser; and a processor, the processor reads data specifying the number of irradiation pulses of the pulsed laser irradiated to a portion of an irradiated object and the difference between the shortest wavelength and the longest wavelength, determines a target spectral line width, controls the second actuator according to the target spectral line width, and controls the first actuator so that the oscillation wavelength changes periodically between the shortest wavelength and the longest wavelength according to the number of irradiation pulses.

Description

Technical Field

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

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

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

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: U.S. Patent Application Publication No. 2002 / 0167975

[0007] Patent Document 2: U.S. Patent Application Publication No. 2013 / 0230064

[0008] Patent Document 3: U.S. Patent Application Publication No. 2005 / 0083983

[0009] Patent Document 4: Japanese Patent Application Laid-Open No. 07-058393

[0010] Patent Document 5: U.S. Patent Application Publication No. 2020 / 0301286 Summary of the invention

[0011] A laser device according to one aspect of the present disclosure comprises: a first actuator for adjusting an oscillation wavelength of a pulsed laser; a second actuator for adjusting a spectral line width of the pulsed laser; and a processor, wherein the processor reads data specifying the number of irradiation pulses of the pulsed laser irradiated to a portion of an object to be irradiated and the difference between the shortest wavelength and the longest wavelength to determine a target spectral line width, the processor controls the second actuator according to the target spectral line width, and the processor controls the first actuator so that the oscillation wavelength changes periodically between the shortest wavelength and the longest wavelength according to the number of irradiation pulses.

[0012] A method for manufacturing an electronic device according to one aspect of the present disclosure includes the following steps: generating a pulsed laser by a laser device, outputting the pulsed laser to an exposure device, exposing the pulsed laser on a photosensitive substrate in the exposure device to manufacture the electronic device, the laser device comprising: a first actuator for adjusting the oscillation wavelength of the pulsed laser; a second actuator for adjusting the spectral line width of the pulsed laser; and a processor, the processor reading data specifying the number of irradiation pulses of the pulsed laser irradiated to a portion of an irradiated object and the difference between the shortest wavelength and the longest wavelength to determine a target spectral line width, the processor controlling the second actuator according to the target spectral line width, and the processor controlling the first actuator so that the oscillation wavelength changes periodically between the shortest wavelength and the longest wavelength according to the number of irradiation pulses. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Hereinafter, several embodiments of the present disclosure will be described as simple examples with reference to the accompanying drawings.

[0014] Figure 1 The structure of an exposure system in a comparative example is schematically shown.

[0015] Figure 2 The structure of a laser device in a comparative example is schematically shown.

[0016] Figure 3 The structure of a laser device in a comparative example is schematically shown.

[0017] Figure 4 The figure shows how the position of the scanning field of the irradiated object changes relative to the position of the pulsed laser.

[0018] Figure 5 The figure shows how the position of the scanning field of the irradiated object changes relative to the position of the pulsed laser.

[0019] Figure 6 The figure shows how the position of the scanning field of the irradiated object changes relative to the position of the pulsed laser.

[0020] Figure 7 This is a graph showing a first example of periodic wavelength change in a comparative example.

[0021] Figure 8 Show Figure 7 The waveform of the moving cumulative spectrum of 30 pulses with wavelength variation is shown.

[0022] Fig. 9 This is a graph showing a second example of periodic wavelength change in the comparative example.

[0023] Fig.10 Show Fig. 9 The waveform of the moving cumulative spectrum of 30 pulses with wavelength variation is shown.

[0024] Fig.11 This is a graph showing a third example of periodic wavelength change in the comparative example.

[0025] Fig.12 Show Fig.11 The waveform of the moving cumulative spectrum of 30 pulses with wavelength variation is shown.

[0026] Fig.13 The structure of the laser device according to the first embodiment is schematically shown.

[0027] Fig.14 The structure of the laser device according to the first embodiment is schematically shown.

[0028] Fig.15 A laser device according to a first modification including an optical system for changing the spectral line width is shown.

[0029] Fig.16 A second modified laser device including an optical system for changing the line width is shown.

[0030] Fig.17 A laser device according to a third modification including an optical system for changing the spectral line width is shown.

[0031] Fig.18 A laser device according to a fourth modification including an optical system for changing the spectral line width is shown.

[0032] Fig.19 A fifth variation of the narrowband device including an optical system for changing the spectral line width is shown.

[0033] Fig. 20 A sixth variation of the narrowband device including an optical system for changing the spectral line width is shown.

[0034] Fig.21 A sixth variation of the narrowband device including an optical system for changing the spectral line width is shown.

[0035] Fig. 22is a flow chart showing the processing steps of line width control and wavelength control performed by the laser control processor.

[0036] Fig.23 This is a flowchart showing the processing procedure of controlling the spectral line width in the first embodiment.

[0037] Fig.24 This is a flowchart showing the processing procedure of controlling the spectral line width in the second embodiment.

[0038] Fig.25 This is a flowchart showing the processing procedure of controlling the spectral line width in the third embodiment.

[0039] Fig.26 Assume that the line width is 0.2 pm, and Figure 7 The moving cumulative spectrum waveform is shown when the wavelength is controlled into a sawtooth wave shape.

[0040] Fig. 27 Assume that the line width is 0.3 pm, and Figure 7 The moving cumulative spectrum waveform is shown when the wavelength is controlled into a sawtooth wave shape.

[0041] Fig.28 Assume that the line width is 0.4 pm, and Figure 7 The moving cumulative spectrum waveform is shown when the wavelength is controlled into a sawtooth wave shape.

[0042] Fig.29 Assume that the line width is 0.5 pm, and Figure 7 The moving cumulative spectrum waveform is shown when the wavelength is controlled into a sawtooth wave shape.

[0043] Fig.30 Assume that the line width is 0.6 pm, and Figure 7 The moving cumulative spectrum waveform is shown when the wavelength is controlled into a sawtooth wave shape.

[0044] Fig.31 Assume that the line width is 0.8 pm, and Figure 7 The moving cumulative spectrum waveform is shown when the wavelength is controlled into a sawtooth wave shape.

[0045] Fig.32 Assume that the line width is 1.0 pm, and Figure 7 The moving cumulative spectrum waveform is shown when the wavelength is controlled into a sawtooth wave shape.

[0046] Fig.33 Assume that the line width is 1.2 pm, and Figure 7 The moving cumulative spectrum waveform is shown when the wavelength is controlled into a sawtooth wave shape.

[0047] Fig.34 It is shown as Figure 7 The graph shows the relationship between the spectral line width and the light intensity ratio when the wavelength is controlled into a sawtooth wave shape.

[0048] Fig.35 It is shown as Figure 7 The graph shows the relationship between the spectral line width and the light intensity ratio when the wavelength is controlled into a sawtooth wave shape.

[0049] Fig.36 Assume that the line width is 0.2 pm, and Fig. 9 The moving cumulative spectrum waveform is shown when the wavelength is controlled into a triangular wave shape.

[0050] Fig.37 Assume that the line width is 0.3 pm, and Fig. 9 The moving cumulative spectrum waveform is shown when the wavelength is controlled into a triangular wave shape.

[0051] Fig.38 Assume that the line width is 0.4 pm, and Fig. 9 The moving cumulative spectrum waveform is shown when the wavelength is controlled into a triangular wave shape.

[0052] Fig.39 Assume that the line width is 0.5 pm, and Fig. 9 The moving cumulative spectrum waveform is shown when the wavelength is controlled into a triangular wave shape.

[0053] Fig.40 Assume that the line width is 0.6 pm, and Fig. 9 The moving cumulative spectrum waveform is shown when the wavelength is controlled into a triangular wave shape.

[0054] Fig.41 Assume that the line width is 0.8 pm, and Fig. 9 The moving cumulative spectrum waveform is shown when the wavelength is controlled into a triangular wave shape.

[0055] Fig.42 Assume that the line width is 1.0 pm, and Fig. 9 The moving cumulative spectrum waveform is shown when the wavelength is controlled into a triangular wave shape.

[0056] Fig.43 Assume that the line width is 1.2 pm, and Fig. 9 The moving cumulative spectrum waveform is shown when the wavelength is controlled into a triangular wave shape.

[0057] Fig.44 It is shown as Fig. 9The graph shows the relationship between the line width and the light intensity ratio when the wavelength is controlled into a triangular wave shape. DETAILED DESCRIPTION

[0058] <Content>

[0059] 1. Comparative Example

[0060] 1.1 Exposure system

[0061] 1.1.1 Structure

[0062] 1.1.2 Action

[0063] 1.2 Laser device 100

[0064] 1.2.1 Structure

[0065] 1.2.2 Action

[0066] 1.3 Narrowband Devices 14

[0067] 1.3.1 Structure

[0068] 1.3.2 Action

[0069] 1.4 Number of irradiation pulses N

[0070] 1.5 Example of periodic wavelength variation

[0071] 1.5.1 Sawtooth Wavelength Change

[0072] 1.5.2 Triangular Wavelength Change

[0073] 1.5.3 Triangular Waveform Wavelength Change in Which the Wavelength is Shifted in the First Half of the Cycle and the Second Half of the Cycle

[0074] 1.6 Issues of Comparative Example

[0075] 2. Laser device 100a that makes the moving cumulative spectrum waveform close to the preferred flat-top shape by controlling the spectrum line width Δλ

[0076] 2.1 Structure

[0077] 2.2 Action

[0078] 2.3 Example of an optical system that changes the line width Δλ

[0079] 2.3.1 Wavefront modifier 15e arranged between output coupling mirror 15 and laser cavity 10

[0080] 2.3.2 Wavefront modulator composed of deformable mirrors 15h

[0081] 2.3.3 Wavefront modulator 15e arranged between the narrowband device 14 and the laser cavity 10

[0082] 2.3.4 Grating 53a capable of changing shape

[0083] 2.3.5 The first prism 41 and the second prism 42 that change the beam expansion rate by rotating in opposite directions

[0084] 2.3.6 Changing the beam expansion ratio by replacing the prism 47

[0085] 2.4 Spectral Line Width Control and Wavelength Control by Laser Control Processor 130

[0086] 2.5 Control of spectral line width Δλ

[0087] 2.6 Function

[0088] 3. Laser device 100a with target maximum spectral line width Δλmax set

[0089] 3.1 Structure and Action

[0090] 3.2 Function

[0091] 4. Laser device 100a that controls the spectral line width Δλ within the allowable range

[0092] 4.1 Structure and Action

[0093] 4.2 Function

[0094] 5. Changes in the moving cumulative spectrum waveform based on the control of the spectrum line width Δλ

[0095] 5.1 Controlling the wavelength into a sawtooth wave

[0096] 5.2 Controlling the wavelength into a triangular wave

[0097] 6. Others

[0098] Below, the embodiments of the present disclosure are described in detail with reference to the accompanying drawings. The embodiments described below show several examples of the present disclosure and do not limit the content of the present disclosure. In addition, the structures and actions described in each embodiment are not necessarily all necessary for the structures and actions of the present disclosure. In addition, the same reference numerals are marked on the same structural elements and repeated descriptions are omitted.

[0099] 1. Comparative Example

[0100] 1.1 Exposure system

[0101] Figure 1The configuration of the exposure system in the comparative example is schematically shown. The comparative example of the present disclosure is a method that the applicant recognizes as only known to the applicant, and is not a publicly known example acknowledged by the applicant himself.

[0102] The exposure system includes a laser device 100 and an exposure device 200. Figure 1 The laser device 100 is schematically shown in FIG.

[0103] The laser device 100 includes a laser control processor 130. The laser device 100 is configured to output a pulsed laser toward the exposure device 200. The laser control processor 130 is a processing device including a memory 132 storing a control program and a CPU (central processing unit) 131 for executing the control program. The laser control processor 130 is specially configured or programmed to execute various processes included in the present disclosure.

[0104] 1.1.1 Structure

[0105] like Figure 1 As shown, the exposure device 200 includes an illumination optical system 201 , a projection optical system 202 , and an exposure control processor 210 .

[0106] The illumination optical system 201 illuminates a reticle pattern of a reticle (not shown) arranged on the reticle stage RT with pulsed laser light incident from the laser device 100 .

[0107] The projection optical system 202 projects the pulsed laser light transmitted through the mask in a reduced size and forms an image on a workpiece (not shown) arranged on a workpiece stage WT. The workpiece is a photosensitive substrate such as a semiconductor wafer coated with a resist film.

[0108] The exposure control processor 210 is a processing device including a memory 212 storing a control program and a CPU 211 executing the control program. The exposure control processor 210 is specially configured or programmed to execute various processes included in the present disclosure.

[0109] 1.1.2 Action

[0110] The exposure control processor 210 sends data including the number of irradiation pulses N, the shortest wavelength λS and the longest wavelength λL, and a trigger signal to the laser control processor 130. The laser control processor 130 controls the laser device 100 according to the data and signal received from the exposure control processor 210.

[0111] The exposure control processor 210 causes the reticle stage RT and the work stage WT to move in parallel in opposite directions in synchronization with each other, thereby exposing the workpiece with the pulsed laser light reflecting the reticle pattern.

[0112] The mask pattern is transferred onto the semiconductor wafer through this exposure process, and then the electronic device can be manufactured through multiple processes.

[0113] 1.2 Laser device 100

[0114] 1.2.1 Structure

[0115] Figure 2 and Figure 3 The structure of the laser device 100 in the comparative example is schematically shown. Figure 2 and Figure 3 , a V axis, an H axis, and a Z axis which are perpendicular to each other are respectively shown. Figure 2 The laser device 100 is shown as viewed in the -V direction. Figure 3 The laser device 100 is shown as viewed in the -H direction.

[0116] The laser device 100 includes a laser cavity 10, a pulse power module (PPM) 13, a band-narrowing device 14, and an output coupling mirror 15 in addition to a laser control processor 130. The band-narrowing device 14 and the output coupling mirror 15 constitute an optical resonator.

[0117] The laser cavity 10 is disposed on the optical path of the optical resonator and is provided with windows 10a and 10b.

[0118] The laser cavity 10 has a pair of electrodes 11a and 11b inside and contains laser gas. As an example, the laser gas contains fluorine gas, argon gas, and neon gas. As another example, the laser gas contains fluorine gas, krypton gas, and neon gas.

[0119] The -V direction and the +V direction coincide with the direction in which the electrodes 11a and 11b face each other. The -Z direction coincides with the traveling direction of the light beam emitted from the window 10a. The +Z direction coincides with the traveling direction of the pulse laser emitted from the window 10b and output via the output coupling mirror 15.

[0120] The pulse power module 13 includes a switch (not shown) and is connected to a charger (not shown).

[0121] The narrowband device 14 includes a beam expander 40 including a first prism 41 and a second prism 42, and a grating 53. The narrowband device 14 will be described in detail later.

[0122] The output coupling mirror 15 is formed by a partially reflecting mirror.

[0123] 1.2.2 Action

[0124] The laser control processor 130 receives data including the number of irradiation pulses N, the shortest wavelength λS, and the longest wavelength λL from the exposure control processor 210. The data may be received from a photolithography control device (not shown) that is different from the exposure device 200. The photolithography control device may control a plurality of exposure devices 200. The laser control processor 130 sends a control signal to the bandwidth narrowing device 14 based on the number of irradiation pulses N, the shortest wavelength λS, and the longest wavelength λL.

[0125] The laser control processor 130 receives a trigger signal from the exposure control processor 210. The laser control processor 130 sends an oscillation trigger signal based on the trigger signal to the pulse power module 13. The switch included in the pulse power module 13 is turned on after receiving the oscillation trigger signal from the laser control unit 31. After the switch is turned on, the pulse power module 13 generates a pulse-shaped high voltage according to the electric energy charged by the charger, and applies the high voltage to the electrodes 11a and 11b.

[0126] When a high voltage is applied to the electrodes 11a and 11b, a discharge is generated between the electrodes 11a and 11b. The laser gas in the laser cavity 10 is excited to transition to a high energy level by the energy of the discharge. Then, when the excited laser gas transitions to a low energy level, light of a wavelength corresponding to the energy level difference is emitted.

[0127] Light generated in the laser cavity 10 is emitted to the outside of the laser cavity 10 through windows 10a and 10b. Light emitted from window 10a enters the band narrowing device 14. Light near a desired wavelength of the light entering the band narrowing device 14 returns to the laser cavity 10 from the band narrowing device 14.

[0128] The output coupling mirror 15 transmits a part of the light emitted from the window 10 b to output the light, and reflects the other part to return the light to the laser cavity 10 .

[0129] In this way, the light emitted from the laser cavity 10 reciprocates between the narrowband device 14 and the output coupling mirror 15. The light is amplified each time it passes through the discharge space between the pair of electrodes 11a and 11b. In addition, the light is narrowbanded each time it returns through the narrowband device 14, and becomes light with a sharp wavelength distribution, and the wavelength distribution has a part of the range of the selected wavelength based on the narrowband device 14 as the central wavelength. The light that is narrowbanded by laser oscillation in this way is output from the output coupling mirror 15 as a pulsed laser. Unless otherwise specified, the wavelength of the pulsed laser refers to the central wavelength.

[0130] The pulse laser light outputted from the laser device 100 is incident on the exposure device 200 .

[0131] 1.3 Narrowband Devices 14

[0132] 1.3.1 Structure

[0133] The first prism 41 is disposed on the optical path of the light beam emitted from the window 10 a . The first prism 41 is supported by a holder 411 .

[0134] The second prism 42 is disposed on the optical path of the light beam that has passed through the first prism 41. The second prism 42 is supported by a holder 421.

[0135] The first prism 41 and the second prism 42 are arranged so that the surfaces of the first prism 41 and the second prism 42, through which the light beams are incident and emitted, are parallel to the V axis. The second prism 42 can be rotated around an axis parallel to the V axis by a rotating table 422. Here, as an example of the rotating table 422, a highly responsive rotating table that is rotated by a piezoelectric element is cited.

[0136] The grating 53 is arranged on the optical path of the light beam after passing through the second prism 42. The direction of the grooves of the grating 53 coincides with the V-axis direction.

[0137] The grating 53 is supported by a holder 531 .

[0138] 1.3.2 Action

[0139] The light emitted from the window 10a changes its traveling direction in a plane parallel to the HZ plane, which is a plane perpendicular to the V axis, through the first prism 41 and the second prism 42, respectively, and expands the beam width in a plane parallel to the HZ plane. As an example, the traveling direction of the light passing through both the first prism 41 and the second prism 42 toward the grating 53 is substantially consistent with the -Z direction.

[0140] The light incident on the grating 53 from the second prism 42 is reflected by the plurality of grooves of the grating 53 and diffracted in a direction corresponding to the wavelength of the light. The grating 53 is configured in a Littrow manner so that the incident angle of the light beam incident on the grating 53 from the second prism 42 and the diffraction angle of the diffracted light of the desired wavelength match.

[0141] The second prism 42 and the first prism 41 reduce the beam width of the light returning from the grating 53 in a plane parallel to the HZ plane, and return the light to the laser cavity 10 through the window 10 a.

[0142] The rotating stage 422 is controlled by the laser control processor 130 .

[0143] When the rotating stage 422 slightly rotates the second prism 42, the traveling direction of the light emitted from the second prism 42 toward the grating 53 slightly changes in a plane parallel to the HZ plane. As a result, the incident angle of the light incident from the second prism 42 to the grating 53 slightly changes. As a result, the selected wavelength based on the narrowband device 14 is adjusted, and the oscillation wavelength of the pulsed laser is adjusted. The rotating stage 422 is equivalent to the first actuator in the present disclosure.

[0144] The laser control processor 130 controls the rotating stage 422 of the second prism 42 based on the shortest wavelength λS and the longest wavelength λL received from the exposure control processor 210 .

[0145] The laser control processor 130 controls the rotating stage 422 for each pulse so that the posture of the second prism 42 changes periodically for each plurality of pulses. Thus, the wavelength of the pulsed laser changes in multiple stages between the shortest wavelength λS and the longest wavelength λL, and changes periodically for each plurality of pulses. In this way, the laser device 100 changes the wavelength over a plurality of pulses, thereby being able to perform multi-wavelength oscillation that outputs pulsed laser light having a plurality of wavelengths.

[0146] Exposure device 200 (see Figure 1 ) depends on the wavelength of the pulsed laser. The pulsed laser that oscillates at multiple wavelengths and enters the exposure device 200 can form images at multiple different positions in the direction of the optical path axis of the pulsed laser, and can substantially increase the depth of focus. For example, when exposing a thick resist film, the imaging performance in the thickness direction of the resist film can also be maintained.

[0147] 1.4 Number of irradiation pulses N

[0148] Figures 4 to 6 The figure shows a situation in which the position of the scanning field SF of the irradiated object changes relative to the position of the pulsed laser. The irradiated object is, for example, a semiconductor wafer. The scanning field SF of the semiconductor wafer corresponds to, for example, a region where a plurality of semiconductor chips formed on the semiconductor wafer are formed. A resist film is applied to the scanning field SF. The width of the scanning field SF in the X-axis direction is the same as the width of the beam cross section B of the pulsed laser at the position of the irradiated object in the X-axis direction. The width of the scanning field SF in the Y-axis direction is larger than the width W of the beam cross section B of the pulsed laser at the position of the irradiated object in the Y-axis direction.

[0149] according to Figure 4 , Figure 5 , Figure 6 The steps of exposing the scanning field SF by pulse laser are performed in the order of Figure 4 As shown in FIG. 1 , the workpiece stage WT is positioned so that the end SFy+ in the +Y direction of the scanning field SF is separated from the end By- in the -Y direction of the beam section B by a predetermined distance in the -Y direction. Then, the workpiece stage WT is accelerated in the +Y direction so that the speed reaches V before the end SFy+ in the +Y direction of the scanning field SF coincides with the end By- in the -Y direction of the beam section B. As shown in FIG. Figure 5 As shown, the workpiece table WT is moved so that the position of the scanning field SF moves linearly at a constant speed V relative to the position of the beam cross section B. Figure 6 As shown, the workpiece stage WT is moved until the -Y direction end SFy- of the scanning field SF passes the +Y direction end By+ of the beam section B, and then the exposure of the scanning field SF is completed. In this way, the exposure is performed while the scanning field SF is moved relative to the beam section B.

[0150] The time T required for moving the scanning field SF at a speed V by a distance corresponding to the width W of the beam cross section B of the pulse laser light is as follows.

[0151] T=W / V

[0152] The number N of irradiation pulses of the pulsed laser light irradiated to any one location in the scanning field SF is the same as the number of pulses of the pulsed laser light generated in the required time T, as described below.

[0153] N=F·T

[0154] =F·W / V

[0155] Here, F is the repetition frequency of the pulsed laser.

[0156] The number of irradiation pulses N is also called the number of N gap pulses.

[0157] 1.5 Example of periodic wavelength variation

[0158] 1.5.1 Sawtooth Wavelength Change

[0159] Figure 7 is a graph showing the first example of periodic wavelength variation in the comparative example. Figure 7 and the following Fig. 9 and Fig.11 In FIG. 1 , the horizontal axis represents the pulse number n, and the vertical axis represents the wavelength. The pulse number n is an integer from 1 to 30, and the pulse number n after 30 returns to 1.

[0160] exist Figure 7 In the example shown, the wavelength changes periodically every 30 pulses between the shortest wavelength λS and the longest wavelength λL. Specifically, during the period of generating the 30 pulses of pulsed laser light from the first (n=1) to the 30th (n=30), the wavelength changes from the shortest wavelength λS to the longest wavelength λL in a manner that extends by a certain wavelength shift amount δλ per pulse. Then, the wavelength of the 31st (n=1) pulse returns to the shortest wavelength λS, and similarly, 30 pulses are set as one cycle, and the wavelength is repeatedly changed from the shortest wavelength λS to the longest wavelength λL. The number of irradiation pulses N is set to 30.

[0161] Next, Figure 7 Such a wavelength variation is called a sawtooth-shaped wavelength variation.

[0162] The wavelength shift amount δλ is a value that defines the wavelength change amount per one pulse. When the wavelength is controlled in a sawtooth wave shape, the wavelength shift amount δλ is calculated by the following formula.

[0163] δλ=(λL-λS) / (N-1)

[0164] When the number of irradiation pulses N is 30 (N=30), the wavelength shift amount δλ becomes a value obtained by dividing λL-λS, a difference between the shortest wavelength λS and the longest wavelength λL, by 29.

[0165] Figure 8 Show Figure 7 The moving cumulative spectrum waveform of 30 pulses with wavelength variation is shown. Figure 8 and the following Fig.10 and Fig.12 In the figure, the horizontal axis shows the wavelength and the vertical axis shows the light intensity. Figure 7 In the wavelength change shown, the wavelength is changed in multiple stages between the shortest wavelength λS and the longest wavelength λL. Figure 8 The moving cumulative spectrum waveform shown contains multiple peaks between the shortest wavelength λS and the longest wavelength λL. Figure 8 If the light intensity of the 30 pulses is kept roughly constant, then Figure 8 The plurality of peaks shown have substantially the same light intensity. In the sawtooth-shaped wavelength change, the wavelength difference between the peaks in the shifted cumulative spectrum waveform is the same as the wavelength shift amount δλ.

[0166] exist Figure 7 In the wavelength change shown, the moving cumulative spectrum waveform of 30 pulses becomes the same waveform regardless of which pulse they start from. For example, the moving cumulative spectrum waveform is the same regardless of whether it is the 30 pulses from the 1st (n=1) to the 30th (n=30), the 30 pulses from the 2nd (n=2) to the 31st (n=1), or the 30 pulses starting from any other pulse. Therefore, the 30 pulses that irradiate any part of the scanning field SF of the irradiated object have the same moving cumulative spectrum waveform. As a result, the deviation of the exposure result caused by the irradiation position is small, and high-quality electronic devices can be manufactured.

[0167] 1.5.2 Triangular Wavelength Change

[0168] Fig. 9 This is a graph showing a second example of periodic wavelength change in the comparative example.

[0169] exist Fig. 9In the example shown, during the period of generating 15 pulses of pulsed laser light from the 1st (n=1) to the 15th (n=15), the wavelength changes from the shortest wavelength λS to the longest wavelength λL in a manner extending by a certain wavelength shift amount δλ per pulse. Then, during the period of generating 15 pulses of pulsed laser light from the 16th (n=16) to the 30th (n=30), the wavelength changes from the longest wavelength λL to the shortest wavelength λS in a manner shortening by a certain wavelength shift amount δλ per pulse. Then, similarly, 30 pulses are set as one cycle, and the operation of extending the wavelength to generate 15 pulses in the first half of the cycle and the operation of shortening the wavelength to generate 15 pulses in the second half of the cycle are repeated. The number of irradiation pulses N is set to 30.

[0170] Next, Fig. 9 Such a wavelength change is called a triangular wave-shaped wavelength change.

[0171] like Fig. 9 As shown in FIG. 1 , when the wavelength is controlled to be in a triangular wave shape, the wavelength shift amount δλ is calculated by the following formula.

[0172] δλ=(λL-λS) / (N / 2-1)

[0173] When the number of irradiation pulses N is 30 (N=30), the wavelength shift amount δλ is a value obtained by dividing 14 by the difference between the shortest wavelength λS and the longest wavelength λL.

[0174] exist Figure 7 In the sawtooth-shaped wavelength change shown in FIG. 1 , the wavelength needs to be changed sharply from the time when the 30th (n=30) pulse is output to the time when the 31st (n=1) pulse is output. Fig. 9 In the triangular wave-shaped wavelength change shown, the need to change the wavelength sharply is reduced.

[0175] Fig.10 Show Fig. 9 The waveform of the moving cumulative spectrum of 30 pulses with wavelength variation is shown. Fig.10 The moving cumulative spectrum waveform shown also contains multiple peaks between the shortest wavelength λS and the longest wavelength λL. Fig.10 In the triangular wave-shaped wavelength change, the wavelength difference between the peaks in the moving cumulative spectrum waveform is the same as the wavelength shift amount δλ.

[0176] exist Fig. 9 In the wavelength change shown, the waveform of the moving cumulative spectrum of 30 pulses becomes the same waveform regardless of the pulse from which it is started.

[0177] exist Figure 7 and Fig. 9In any wavelength change, sometimes Figure 8 and Fig.10 The moving cumulative spectrum waveform shown has multiple sharp peaks separated from each other, which cannot be said to be a preferred flat top shape. In this case, in the exposure device 200, imaging is performed at dispersed positions in the direction of the optical path axis of the pulsed laser, and stable exposure performance may not be obtained.

[0178] 1.5.3 Triangular Waveform Wavelength Change in Which the Wavelength is Shifted in the First Half of the Cycle and the Second Half of the Cycle

[0179] Fig.11 This is a graph showing a third example of periodic wavelength change in the comparative example.

[0180] exist Fig.11 In the example shown, the wavelengths are shifted so that no pair of pulses having the same wavelength is generated in each of the 15 pulses in the first half of the cycle from the 1st (n=1) to the 15th (n=15) and each of the 15 pulses in the second half of the cycle from the 16th (n=16) to the 30th (n=30). Specifically, the wavelength shift amount of each of the 15 pulses in the first half of the cycle is set to δλ. 1 When , the 15 pulses from the 1st (n=1) to the 15th (n=15) and the 15 pulses from the 30th (n=30) to the 16th (n=16) have δλ 1 The wavelength difference is / 2. The number of irradiation pulses N is 30.

[0181] like Fig.11 As shown in FIG. 1 , when the wavelength is controlled to be a triangular wave in which the wavelength is shifted in the first half of the cycle and the second half of the cycle, the wavelength shift amount δλ 1 It is calculated by the following formula.

[0182] δλ 1 =(λL-λS) / ((N-1) / 2)

[0183] However, the wavelength is shifted when the 1st (n=1) and N / 2+1th (n=N / 2+1) pulses are output, so the wavelength shift amount δλ is 2 It is calculated by the following formula.

[0184] δλ 2 =δλ 1 / 2

[0185] =(λL-λS) / (N-1)

[0186] The moving cumulative spectrum waveform in this case may have a shape close to a preferred flat top shape because the valleys between the peaks corresponding to the pulses in the first half of the cycle are filled with the peaks corresponding to the pulses in the second half of the cycle.

[0187] 1.6 Issues of Comparative Example

[0188] However, in Fig.11 In the wavelength change shown, when the difference λL-λS between the shortest wavelength λS and the longest wavelength λL increases, the waveform of the moving integrated spectrum may become a state that cannot be said to be a preferable flat top shape.

[0189] Fig.12 Show Fig.11 The waveform of the moving cumulative spectrum of 30 pulses with wavelength variation is shown. When the intervals between the peaks corresponding to the pulses in the first half of the cycle widen, the valleys between the peaks cannot be filled by the peaks corresponding to the pulses in the second half of the cycle. Fig.12 In the case of , the peaks corresponding to the pulses in the first half of the cycle and the peaks corresponding to the pulses in the second half of the cycle appear respectively. Fig.12 There are 30 peaks in the moving cumulative spectrum waveform. The wavelength difference between the peaks is the wavelength shift δλ 1 One half of .

[0190] In the embodiment described below, the spectral line width Δλ of the pulsed laser light is controlled so that the waveform of the moving integrated spectrum approaches a preferred flat-top shape.

[0191] 2. Laser device 100a that makes the moving cumulative spectrum waveform close to the preferred flat-top shape by controlling the spectrum line width Δλ

[0192] 2.1 Structure

[0193] Fig.13 and Fig.14 The structure of the laser device 100 a according to the first embodiment is schematically shown. Fig.13 Equivalent to the comparison example Figure 2 The laser device 100a is viewed from the same direction. Fig.14 Equivalent to the comparison example Figure 3 The laser device 100a is viewed from the same direction.

[0194] The laser device 100a includes a wavefront modulator 15a that transmits a part of the light instead of the output coupling mirror 15. The laser device 100a further includes a detector 17 and a shutter 18.

[0195] The wavefront adjuster 15a comprises a cylindrical plano-convex lens 15b, a cylindrical plano-concave lens 15c and a linear stage 15d. The cylindrical plano-concave lens 15c is located between the laser cavity 10 and the cylindrical plano-convex lens 15b.

[0196] The cylindrical plano-convex lens 15b and the cylindrical plano-concave lens 15c are arranged so that the convex surface of the cylindrical plano-convex lens 15b and the concave surface of the cylindrical plano-concave lens 15c face each other. The convex surface of the cylindrical plano-convex lens 15b and the concave surface of the cylindrical plano-concave lens 15c respectively have focal axes parallel to the V axis. The flat surface on the opposite side of the convex surface of the cylindrical plano-convex lens 15b is coated with a partial reflection film. The wavefront adjuster 15a and the narrowband device 14 constitute an optical resonator.

[0197] A beam splitter 17a is arranged on the optical path of the pulse laser light outputted through the wavefront modifier 15a. The beam splitter 17a transmits a part of the pulse laser light with high transmittance and reflects the other part. A detector 17 is arranged on the optical path of the pulse laser light reflected by the beam splitter 17a. A window 17b may also be arranged between the beam splitter 17a and the detector 17.

[0198] The shutter 18 can be disposed on the optical path of the pulse laser light after passing through the beam splitter 17 a .

[0199] 2.2 Action

[0200] The linear stage 15d moves the cylindrical plano-concave lens 15c along the optical path between the laser cavity 10 and the cylindrical plano-convex lens 15b. As a result, the wavefront of the light from the wavefront adjuster 15a toward the narrowband device 14 is adjusted. The wavefront is adjusted, thereby adjusting the spectral line width Δλ of the pulsed laser. The wavefront adjuster 15a is equivalent to the second actuator in the present disclosure.

[0201] The detector 17 obtains the measurement data of the spectral line width Δλ of the pulsed laser light. The detector 17 may further obtain the measurement data of the wavelength and pulse energy of the pulsed laser light. The detector 17 sends the measurement data to the laser control processor 130 .

[0202] The shutter 18 is switched between a first state in which the pulsed laser is blocked and a second state in which the pulsed laser is passed toward the exposure device 200 by the driving unit 18a so as to appear and disappear in the optical path of the pulsed laser. Putting the shutter 18 in the first state is referred to as "closing the shutter 18", and putting the shutter 18 in the second state is referred to as "opening the shutter 18".

[0203] Reference Figure 22 to Figure 25 The line width control and wavelength control performed by the laser control processor 130 will be described later.

[0204] 2.3 Example of an optical system that changes the spectral line width Δλ

[0205] 2.3.1 Wavefront modifier 15e arranged between output coupling mirror 15 and laser cavity 10

[0206] Fig.15A laser device 100 b according to a first modification including an optical system for changing the spectral line width Δλ is shown. Fig.15 Equivalent to Fig.13 The figure of the laser device 100b is viewed from the same direction, but the illustration of some components is simplified or omitted.

[0207] exist Fig.15 In the embodiment, a wavefront adjuster 15e is arranged between the output coupling mirror 15 and the laser cavity 10. The wavefront adjuster 15e is equivalent to the second actuator in the present disclosure. The wavefront adjuster 15e includes a cylindrical plano-convex lens 15f instead of the cylindrical plano-convex lens 15b, and the cylindrical plano-convex lens 15f does not include a partial reflection film. The cylindrical plano-convex lens 15f allows the light emitted from the laser cavity 10 to pass through with high transmittance and enter the output coupling mirror 15. The output coupling mirror 15 and the narrowband device 14 constitute an optical resonator.

[0208] 2.3.2 Wavefront modulator composed of deformable mirrors 15h

[0209] Fig.16 A second modified laser device 100 c including an optical system for changing the line width Δλ is shown. Fig.16 Equivalent to Fig.13 The figure of the laser device 100 c is viewed from the same direction, but the illustration of some components is simplified or omitted.

[0210] exist Fig.16 In the embodiment, the wavefront adjuster 15h is composed of a deformable mirror with high reflectivity. The wavefront adjuster 15h is equivalent to the second actuator in the present disclosure. The deformable mirror is a mirror that can change the curvature of the reflection surface by extending and retracting the telescopic part 15i. The reflection surface of the deformable mirror is a cylindrical surface, and the focal axis of the reflection surface is parallel to the V axis. The wavefront adjuster 15h and the narrowband device 14 constitute an optical resonator.

[0211] A beam splitter 15g as an output coupling mirror is arranged on the optical path between the wavefront adjuster 15h and the laser cavity 10. The beam splitter 15g transmits a part of the light emitted from the window 10b, thereby allowing the light to reciprocate between the wavefront adjuster 15h and the narrowband device 14. The beam splitter 15g reflects another part of the light emitted from the window 10b, thereby outputting it toward the exposure device 200 as a pulsed laser.

[0212] 2.3.3 Wavefront modulator 15e arranged between the narrowband device 14 and the laser cavity 10

[0213] Fig.17 A laser device 100d according to a third modification including an optical system for changing the line width Δλ is shown. Fig.17 Equivalent to Fig.13The figure of the laser device 100d is viewed in the same direction, but the illustration of some components is simplified or omitted.

[0214] exist Fig.17 In the embodiment, a wavefront adjuster 15e is arranged between the narrowband device 14 and the laser cavity 10. The structure of the wavefront adjuster 15e is similar to that of the reference Fig.15 The structure is the same as that described above. The output coupling mirror 15 and the band-narrowing device 14 constitute an optical resonator.

[0215] 2.3.4 Grating 53a capable of changing shape

[0216] Fig.18 A fourth modified laser device 100 e including an optical system for changing the line width Δλ is shown. Fig.18 Equivalent to Fig.13 The figure of the laser device 100e is viewed in the same direction, but the illustration of some components is simplified or omitted.

[0217] The laser device 100e includes a narrowband device 14e, and the narrowband device 14e includes a grating 53a. The curvature of the envelope surface 53c of the groove of the grating 53a is configured to be changeable by the extension and contraction of the telescopic portion 53b. The envelope surface 53c of the groove of the grating 53a is a cylindrical surface, and the focal axis of the envelope surface 53c is parallel to the V axis. The output coupling mirror 15 and the narrowband device 14e constitute an optical resonator. By changing the curvature of the envelope surface 53c of the groove of the grating 53a, the spectral line width Δλ of the pulsed laser is changed. The grating 53a is equivalent to the second actuator in the present disclosure.

[0218] 2.3.5 The first prism 41 and the second prism 42 that change the beam expansion rate by rotating in opposite directions

[0219] Fig.19 A fifth modified narrowband device 14f including an optical system for changing the spectral line width Δλ is shown.

[0220] The first prism 41 can be rotated around an axis parallel to the V axis by means of a rotating table 412. Figure 2 In the embodiment, by rotating the second prism 42, the incident angle of the light incident on the grating 53 is changed, and the selected wavelength is changed. Fig.19 In the embodiment of the present invention, the first prism 41 and the second prism 42 are rotated in opposite directions. When the first prism 41 and the second prism 42 are rotated in opposite directions, the incident angle of the light incident on the grating 53 does not change significantly, but the beam expansion rate of the light realized by the first prism 41 and the second prism 42 changes. Therefore, the wavelength of the pulsed laser does not change significantly, but the spectral line width Δλ of the pulsed laser changes.

[0221] By adjusting the rotation angles of the first prism 41 and the second prism 42 respectively, the incident angle of the light incident on the grating 53 and the beam expansion rate of the light realized by the first prism 41 and the second prism 42 can also be changed. In this way, both the wavelength and the spectral line width Δλ of the pulsed laser can be changed. The rotating tables 412 and 422 constitute both the first actuator and the second actuator in the present disclosure. The laser device including such a narrowband device 14f is also equivalent to the laser device of the present disclosure having the first actuator and the second actuator.

[0222] 2.3.6 Changing the beam expansion ratio by replacing the prism 47

[0223] Fig. 20 and Fig.21 A sixth modified bandwidth narrowing device 14g including an optical system for changing the spectral line width Δλ is shown. The bandwidth narrowing device 14g includes prisms 43 to 47 .

[0224] like Fig. 20 As shown, prisms 43, 44, 45, and 46 are arranged in this order from the laser cavity 10 side toward the grating 53. The prism 44 changes both the beam width and the traveling direction of the light incident from the prism 43 and causes the light to enter the prism 45.

[0225] The prism 44 and the prism 47 are arranged on a single-axis stage 48. Fig.21 As shown in FIG. 4 , prism 47 can be arranged on the optical path of the optical resonator instead of prism 44. Prism 47 changes the traveling direction of light incident from prism 43 and makes it incident on prism 45 in the same way as prism 44. However, prism 47 differs from prism 44 in the expansion rate of the beam width. For example, prism 47 can also make the light incident from prism 43 incident on prism 45 without expanding the beam width.

[0226] By replacing the prism 47 and the prism 44, the incident angle of the light incident from the prism 46 to the grating 53 does not change significantly, but the beam width of the light incident from the prism 46 to the grating 53 changes. That is, the expansion rate of the beam width in the beam expander 40 changes. Therefore, before and after the replacement of the prism 47 and the prism 44, the wavelength of the pulsed laser does not change significantly, but the spectral line width Δλ of the pulsed laser changes. The single-axis stage 48 is equivalent to the second actuator in the present disclosure.

[0227] 2.4 Spectral Line Width Control and Wavelength Control by Laser Control Processor 130

[0228] Fig. 22 : is a flowchart showing the processing steps of line width control and wavelength control performed by the laser control processor 130. Fig. 22 and the following Figure 23 to Figure 25 Examples include Figure 7The process shown here is performed when the wavelength is controlled to be a sawtooth wave.

[0229] In S100, the laser control processor 130 reads the control parameter data received from the exposure control processor 210. The data read by the laser control processor 130 includes the number of irradiation pulses N of the pulsed laser irradiated to one part of the irradiated object and the combination of the shortest wavelength λS and the longest wavelength λL. The combination of the shortest wavelength λS and the longest wavelength λL is an example of data specifying the difference λL-λS between the shortest wavelength λS and the longest wavelength λL in the present disclosure.

[0230] Alternatively, the laser control processor 130 may read in, instead of the combination of the shortest wavelength λS and the longest wavelength λL, any one of the combination of the shortest wavelength λS and the difference λL-λS, the combination of the longest wavelength λL and the difference λL-λS, and the combination of the average wavelength (λS+λL) / 2 and the difference λL-λS.

[0231] In S110 , the laser control processor 130 calculates the wavelength shift amount δλ by the following equation.

[0232] δλ=(λL-λS) / (N-1)

[0233] In S120, the laser control processor 130 controls the spectral line width Δλ. Figure 23 to Figure 25 The details of S120 will be described later.

[0234] S130 to S200 are processes for controlling the rotating stage 422 so that the oscillation wavelength is periodically changed between the shortest wavelength λS and the longest wavelength λL for each irradiation pulse number N. In S130 , the laser control processor 130 sets the value of the pulse number n to 1.

[0235] In S140 , the laser control processor 130 calculates the target wavelength λt using the following equation.

[0236] λt=λS+(n-1)·δλ

[0237] If the value of the pulse number n is 1, the target wavelength λt becomes the same value as the shortest wavelength λS, and each time the value of the pulse number n increases by 1, the wavelength shift amount δλ is added to the target wavelength λt.

[0238] In S150, the laser control processor 130 controls the rotating stage 422 according to the target wavelength λt. By controlling the rotating stage 422, the second prism 42 rotates, and the selected wavelength by the narrowband device 14 changes.

[0239] In S160, the laser control processor 130 determines whether laser oscillation has occurred. The determination of whether laser oscillation has occurred is based on the data received from the detector 17. Alternatively, the determination may be made based on whether an oscillation trigger signal is sent to the pulse power module 13.

[0240] In S170, the laser control processor 130 determines whether the value of the pulse number n is greater than the irradiation pulse number N. When the value of the pulse number n is less than the irradiation pulse number N (S170: No), the laser control processor 130 advances the process to S180. When the value of the pulse number n is greater than the irradiation pulse number N (S170: Yes), the laser control processor 130 advances the process to S190.

[0241] In S180 , the laser control processor 130 adds 1 to the value of the pulse number n to update the value of n. After S180 , the laser control processor 130 returns the process to S140 .

[0242] In S190, the laser control processor 130 determines whether to terminate wavelength control. If wavelength control is not terminated (S190: No), the laser control processor 130 advances the process to S200. If wavelength control is terminated (S190: Yes), the laser control processor 130 terminates the process of this flowchart.

[0243] In S200, the laser control processor 130 determines whether to change the control parameters. If the control parameters are not changed (S200: No), the laser control processor 130 returns the process to S130. In S130, the pulse number n is returned to 1 and the above-mentioned operation is repeated, thereby changing the wavelength in a sawtooth wave shape. If the control parameters are changed (S200: Yes), the laser control processor 130 returns the process to S100.

[0244] 2.5 Control of spectral line width Δλ

[0245] Fig.23 This is a flowchart showing the processing procedure of controlling the spectral line width Δλ in the first embodiment. Fig.23 The processing shown is equivalent to Fig. 22 The S120 subroutine.

[0246] In S121 , the laser control processor 130 determines the target minimum line width Δλmin as a value calculated by the following equation: The target minimum line width Δλmin is a lower limit value of the line width control and is an example of the target line width in the present disclosure.

[0247] Δλmin=Dmin·(λL-λS) / (N-1)

[0248] Dmin is a coefficient, and is preferably greater than 1. For the range of Dmin, refer to Fig.34 , Fig.35 , Fig.44 etc. will be described later. The target minimum spectral line width Δλmin is equivalent to the value obtained by multiplying the wavelength difference between peaks in the moving cumulative spectrum waveform (λL-λS) / (N-1) by the coefficient Dmin. Therefore, the target minimum spectral line width Δλmin is set so that the spectral line width Δλ increases as the wavelength difference between peaks (λL-λS) / (N-1) increases. Fig.23 In the example, it is also possible not to set the upper limit value of the spectral line width control.

[0249] Fig.23 The process of controlling the wavelength to be sawtooth wave is shown, but in the case of Fig. 9 When the wavelength is controlled to be in a triangular wave shape as shown, the target minimum line width Δλmin is calculated by the following formula.

[0250] Δλmin=Dmin·(λL-λS) / (N / 2-1)

[0251] The target minimum spectral line width Δλmin is equivalent to the value obtained by multiplying the wavelength difference between peaks in the moving cumulative spectrum waveform (λL-λS) / (N / 2-1) by the coefficient Dmin. Therefore, the target minimum spectral line width Δλmin is set so that the spectral line width Δλ increases as the wavelength difference between peaks (λL-λS) / (N / 2-1) increases.

[0252] In such Fig.11 When the wavelength is controlled to be in a triangular wave shape in which the wavelength is shifted in the first half of the cycle and the second half of the cycle as shown, the target minimum line width Δλmin is calculated by the following formula.

[0253] Δλmin=Dmin·(λL-λS) / (N-1)

[0254] The target minimum spectral line width Δλmin corresponds to a value obtained by multiplying the wavelength difference (λL-λS) / (N-1) between peaks in the moving cumulative spectrum waveform by a coefficient Dmin.

[0255] By determining the target line width in this way, the target line width becomes larger when the difference λL-λS between the shortest wavelength λS and the longest wavelength λL is the first value and the number of irradiation pulses N is the second value than the target line width when the difference λL-λS is the third value greater than the first value and the number of irradiation pulses N is the fourth value less than the second value. Alternatively, the target line width becomes larger when the difference λL-λS between the shortest wavelength λS and the longest wavelength λL is the first value and the number of irradiation pulses N is the second value than the target line width when the difference λL-λS is the third value greater than the first value and the number of irradiation pulses N is the fourth value less than the second value.

[0256] Following S121, in S123, the laser control processor 130 closes the shutter 18 and starts adjusting the oscillation.

[0257] In S124 , the laser control processor 130 receives the measurement data of the spectral line width Δλ from the detector 17 , and calculates the measurement value of the spectral line width Δλ based on the measurement data.

[0258] In S125 , the laser control processor 130 determines whether the measured value of the line width Δλ is equal to or larger than the target minimum line width Δλmin.

[0259] When the measured value of the line width Δλ is smaller than the target minimum line width Δλmin ( S125 : No), the laser control processor 130 advances the process to S126 .

[0260] In S126, the laser control processor 130 controls the wavefront adjuster 15a to increase the spectral line width Δλ.

[0261] After S126, the laser control processor 130 returns the process to S124.

[0262] When the measured value of the line width Δλ is equal to or larger than the target minimum line width Δλmin ( S125 : YES), the laser control processor 130 advances the process to S129 .

[0263] In S129 , the laser control processor 130 ends adjusting the oscillation and opens the shutter 18 .

[0264] After S129, the laser control processor 130 ends the processing of this flowchart and returns to Fig. 22 Processing shown.

[0265] 2.6 Function

[0266] According to the first embodiment, the laser device 100a includes a rotating table 422 for adjusting the oscillation wavelength of the pulsed laser, a wavefront adjuster 15a for adjusting the spectral line width Δλ of the pulsed laser, and a laser control processor 130. The laser control processor 130 reads data specifying the number of irradiation pulses N of the pulsed laser irradiated to one portion of the irradiated object and the difference λL-λS between the shortest wavelength λS and the longest wavelength λL, determines a target minimum spectral line width Δλmin, controls the wavefront adjuster 15a based on the target minimum spectral line width Δλmin, and controls the rotating table 422 so that the oscillation wavelength changes periodically between the shortest wavelength λS and the longest wavelength λL per the number of irradiation pulses N.

[0267] Thus, by controlling the line width Δλ according to the number of irradiation pulses N and the difference λL-λS between the shortest wavelength λS and the longest wavelength λL, a plurality of sharp peaks in the shift integrated spectrum can be mitigated.

[0268] According to the first embodiment, the laser device 100a further includes a shutter 18 disposed on the optical path of the pulsed laser. The laser control processor 130 determines the target minimum spectral line width Δλmin as the target spectral line width, closes the shutter 18, controls the wavefront adjuster 15a to gradually increase the spectral line width Δλ, and opens the shutter 18 after the measured value of the spectral line width Δλ becomes greater than the target minimum spectral line width Δλmin.

[0269] Thus, the output of pulse laser to exposure device 200 is stopped until pulse laser having a target minimum line width Δλmin or more is obtained, and after pulse laser having a target minimum line width Δλmin or more can be output, it can be output to exposure device 200.

[0270] According to the first embodiment, the moving cumulative spectrum waveform of each irradiation pulse number N of the pulse laser includes multiple peaks, and the laser control processor 130 determines the target minimum spectral line width Δλmin in such a way that the spectral line width Δλ increases when the wavelength difference between the peaks (λL-λS) / (N-1) increases.

[0271] Thus, the target minimum line width Δλmin can be determined to be an appropriate value based on the wavelength difference between peaks (λL-λS) / (N-1).

[0272] Regarding other aspects, the first embodiment is the same as the comparative example.

[0273] 3. Laser device 100a with target maximum spectral line width Δλmax set

[0274] 3.1 Structure and Action

[0275] Fig.24This is a flowchart showing the processing procedure of controlling the spectral line width Δλ in the second embodiment. Fig.24 The processing shown is equivalent to Fig. 22 The structure of the laser device 100a of the second embodiment is the same as that of the first embodiment, and the operation of the laser device 100a of the second embodiment is the same as that of the first embodiment except for the control of the spectral line width Δλ.

[0276] The process of S121 is the same as the corresponding process in the first embodiment.

[0277] Following S121, in S122a, the laser control processor 130 determines the target maximum line width Δλmax as a value calculated by the following equation: The target maximum line width Δλmax is an upper limit value of the line width control and is an example of the target line width in the present disclosure.

[0278] Δλmax=Dmax·(λL-λS) / (N-1)

[0279] Dmax is a coefficient, preferably less than 2.5. For the range of Dmax, refer to Fig.34 , Fig.35 , Fig.44 etc. will be described later. The target maximum spectral line width Δλmax is equivalent to the value obtained by multiplying the wavelength difference between peaks in the moving cumulative spectrum waveform (λL-λS) / (N-1) by the coefficient Dmax. Therefore, the target maximum spectral line width Δλmax is set so that the spectral line width Δλ increases as the wavelength difference between peaks (λL-λS) / (N-1) increases.

[0280] Fig.24 The process of controlling the wavelength to be sawtooth wave is shown, but in the case of Fig. 9 When the wavelength is controlled to be in a triangular wave shape as shown, the target maximum line width Δλmax is calculated by the following formula.

[0281] Δλmax=Dmax·(λL-λS) / (N / 2-1)

[0282] That is, the target maximum line width Δλmax is set so that the line width Δλ increases as the wavelength difference between peaks (λL-λS) / (N / 2-1) increases.

[0283] In such Fig.11 When the wavelength is controlled to be in a triangular wave shape in which the wavelength is shifted in the first half of the cycle and the second half of the cycle as shown, the target maximum line width Δλmax is calculated by the following formula.

[0284] Δλmax=Dmax·(λL-λS) / (N-1)

[0285] The processes of S123 to S126 after S122a are the same as the corresponding processes in the first embodiment. If the determination of S125 is "YES", the laser control processor 130 advances the process to S127a.

[0286] In S127a, the laser control processor 130 determines whether the measured value of the line width Δλ is equal to or smaller than the target maximum line width Δλmax.

[0287] When the measured value of the line width Δλ is larger than the target maximum line width Δλmax ( S127 a : No), the laser control processor 130 advances the process to S128 a .

[0288] In S128a, the laser control processor 130 controls the wavefront adjuster 15a to reduce the spectral line width Δλ.

[0289] After S128a, the laser control processor 130 returns the process to S124.

[0290] When the measured value of the line width Δλ is equal to or smaller than the target maximum line width Δλmax ( S127 a : YES), the laser control processor 130 advances the process to S129 .

[0291] The process of S129 is the same as the corresponding process in the first embodiment.

[0292] After S129, the laser control processor 130 ends the processing of this flowchart and returns to Fig. 22 Processing shown.

[0293] 3.2 Function

[0294] According to the second embodiment, the spectrum width can be controlled to be between the target minimum spectrum line width Δλmin and the target maximum spectrum line width Δλmax.

[0295] Regarding other aspects, the second embodiment is the same as the first embodiment.

[0296] 4. Laser device 100a that controls the spectral line width Δλ within the allowable range

[0297] 4.1 Structure and Action

[0298] Fig.25 This is a flowchart showing the processing procedure of controlling the spectral line width Δλ in the third embodiment. Fig.25 The processing shown is equivalent to Fig. 22The structure of the laser device 100a of the third embodiment is the same as that of the first embodiment, and the operation of the laser device 100a of the third embodiment is the same as that of the first embodiment except for the control of the spectral line width Δλ.

[0299] In S121b, the laser control processor 130 determines the target line width Δλt as a value calculated by the following equation.

[0300] Δλt=D·(λL-λS) / (N-1)

[0301] D is a coefficient, and is preferably greater than or equal to 1 and less than or equal to 2.5. Fig.34 , Fig.35 , Fig.44 The target line width Δλt is equivalent to the value obtained by multiplying the wavelength difference (λL-λS) / (N-1) between the peaks in the moving cumulative spectrum waveform by the coefficient D. Therefore, the target line width Δλt is set so that the line width Δλ increases as the wavelength difference (λL-λS) / (N-1) between the peaks increases.

[0302] Fig.25 The process of controlling the wavelength to be sawtooth wave is shown, but in the case of Fig. 9 When the wavelength is controlled to be in a triangular wave shape as shown, the target line width Δλt is calculated by the following formula.

[0303] Δλt=D·(λL-λS) / (N / 2-1)

[0304] That is, the target line width Δλt is set so that the line width Δλ increases as the wavelength difference between peaks (λL-λS) / (N / 2-1) increases.

[0305] In such Fig.11 When the wavelength is controlled to be in a triangular wave shape in which the wavelength is shifted in the first half of the cycle and the second half of the cycle as shown, the target line width Δλt is calculated by the following formula.

[0306] Δλt=D·(λL-λS) / (N-1)

[0307] The processes of S123 and S124 after S121b are the same as the corresponding processes in the first embodiment.

[0308] Following S124, in S125b, the laser control processor 130 determines whether the measured value of the line width Δλ is equal to or greater than the lower limit value of the allowable range using the following equation.

[0309] Δλ≥Δλt-Δλerror

[0310] Δλerror is an allowable error, and the lower limit value of the allowable range is obtained by subtracting the allowable error Δλerror from the target line width Δλt.

[0311] When the measured value of the line width Δλ is smaller than the lower limit value of the allowable range ( S125 b : No), the laser control processor 130 advances the process to S126 .

[0312] The process of S126 is the same as the corresponding process in the first embodiment.

[0313] After S126, the laser control processor 130 returns the process to S124.

[0314] When the measured value of the line width Δλ is equal to or greater than the lower limit value of the allowable range ( S125 b : YES), the laser control processor 130 advances the process to S127 b .

[0315] In S127b, the laser control processor 130 determines whether the measured value of the line width Δλ is equal to or less than the upper limit of the allowable range using the following equation.

[0316] Δλ≤Δλt+Δλerror

[0317] The upper limit value of the permissible range is obtained by adding the permissible error Δλerror to the target spectral line width Δλt.

[0318] When the measured value of the line width Δλ is larger than the upper limit value of the allowable range ( S127 b : No), the laser control processor 130 advances the process to S128 a .

[0319] In S128a, the laser control processor 130 controls the wavefront adjuster 15a to reduce the spectral line width Δλ.

[0320] After S128a, the laser control processor 130 returns the process to S124.

[0321] When the measured value of the line width Δλ is equal to or less than the upper limit value of the allowable range ( S127 b : YES), the laser control processor 130 advances the process to S129 .

[0322] The process of S129 is the same as the corresponding process in the first embodiment.

[0323] After S129, the laser control processor 130 ends the processing of this flowchart and returns to Fig. 22 Processing shown.

[0324] 4.2 Function

[0325] According to the third embodiment, the spectral line width Δλ can be controlled within the permissible range defined by the permissible error Δλerror around the target spectral line width Δλt.

[0326] Regarding other aspects, the third embodiment is the same as the first embodiment.

[0327] 5. Changes in the moving cumulative spectrum waveform based on the control of the spectrum line width Δλ

[0328] 5.1 Controlling the wavelength into a sawtooth wave

[0329] Figure 26 to Figure 33 Shown as Figure 7 The moving cumulative spectrum waveform is shown when the wavelength is controlled to be a sawtooth wave. Figure 26 to Figure 33 In the figure, the horizontal axis shows the wavelength and the vertical axis shows the light intensity. Figure 26 to Figure 33 In all cases, the number of irradiation pulses N is set to 30, and the wavelength difference between the shortest wavelength λS and the longest wavelength λL is set to 10 pm. Figure 26 to Figure 33 In , the line widths Δλ are different from each other. Fig.26 In the spectrum, the line width Δλ is 0.2pm. Fig. 27 In the spectrum, the line width Δλ is 0.3 pm. Fig.28 In the spectrum, the line width Δλ is 0.4 pm. Fig.29 In the spectrum, the line width Δλ is 0.5 pm. Fig.30 In the spectrum, the line width Δλ is 0.6 pm. Fig.31 In the spectrum, the line width Δλ is 0.8 pm. Fig.32 In the spectrum, the line width Δλ is 1.0 pm. Fig.33 In the figure, the line width Δλ is 1.2 pm. The line width Δλ is the full width at half maximum.

[0330] like Figure 26 to Figure 28 As shown, the smaller the line width Δλ is, the steeper the peak corresponding to each pulse in the moving cumulative spectrum waveform becomes. Conversely, the larger the line width Δλ is, the more the steepness of the peak corresponding to each pulse in the moving cumulative spectrum waveform is relaxed.

[0331] exist Figure 26 to Figure 28 In the figure, the maximum intensity Imax and the minimum intensity Imin of the flat-top region are shown respectively. The flat-top region is the wavelength region between the shortest wavelength λS and the longest wavelength λL, which means the wavelength region where the moving cumulative spectrum waveform is regarded as a flat-top shape. The maximum intensity Imax of the flat-top region is the maximum value of the light intensity in the wavelength region from the shortest wavelength λS to the longest wavelength λL in the moving cumulative spectrum waveform. The minimum intensity Imin of the flat-top region is the minimum value of the light intensity in the wavelength region from the wavelength equivalent to λS+Δλ to the wavelength equivalent to λL-Δλ in the moving cumulative spectrum waveform.

[0332] like Figure 29 to Figure 33 As shown in FIG. 1 , when the line width Δλ is further increased, the wavelength region near the average wavelength in the moving cumulative spectrum waveform becomes roughly flat. However, as the line width Δλ increases, the inclination in the wavelength region near the shortest wavelength λS and the longest wavelength λL in the moving cumulative spectrum waveform becomes gentle, and sometimes it cannot be said to be a preferred flat-top shape.

[0333] exist Figure 29 to Figure 33 The maximum intensity Imax and the minimum intensity Imin of the flat top area are shown in 2 The minimum intensity of the flat top area Imin 2 It is the minimum value of the light intensity in the wavelength range from the shortest wavelength λS to the longest wavelength λL in the moving integrated spectrum waveform.

[0334] exist Figure 26 to Figure 28 The minimum intensity Imin is omitted 2 . Figure 29 to Figure 33 The illustration of the minimum intensity Imin is omitted.

[0335] Fig.34 It is shown as Figure 7 FIG. 4 is a graph showing the relationship between the line width Δλ and the light intensity ratio Imin / Imax when the wavelength is controlled into a sawtooth wave shape. Fig.34 In addition to the spectral line width Δλ, the horizontal axis also shows the normalized spectral line width Δλ / ((λL-λS) / (N-1)). The normalized spectral line width Δλ / ((λL-λS) / (N-1)) is a parameter obtained by dividing the spectral line width Δλ by the wavelength difference between peaks (λL-λS) / (N-1).

[0336] The higher the light intensity ratio Imin / Imax is, the more the sharpness of the moving cumulative spectrum waveform is relaxed. In order to obtain stable exposure performance, the light intensity ratio Imin / Imax is preferably 0.71 or more, and more preferably 0.90 or more.

[0337] according to Fig.34 In order to make the light intensity ratio Imin / Imax greater than 0.71, the normalized line width Δλ / ((λL-λS) / (N-1)) is preferably greater than 1. In order to make the light intensity ratio Imin / Imax greater than 0.90, the normalized line width Δλ / ((λL-λS) / (N-1)) is preferably greater than 1.2.

[0338] Fig.35 It is shown as Figure 7 The line width Δλ and the light intensity ratio Imin when the wavelength is controlled to be sawtooth wave are shown in FIG. 2 / Imax curve diagram. Fig.35 The horizontal axis of shows, in addition to the spectral line width Δλ, the normalized spectral line width Δλ / ((λL-λS) / (N-1)).

[0339] Light intensity ratio Imin 2 The higher / Imax is, the less sharp the peaks corresponding to the pulses in the moving cumulative spectrum waveform are, and the steeper the slopes in the wavelength regions near the shortest wavelength λS and the longest wavelength λL in the moving cumulative spectrum waveform are, forming a preferred flat-top shape. In order to obtain stable exposure performance, it is preferred that the light intensity be greater than Imin. 2 / Imax is 0.71 or more.

[0340] according to Fig.35 , in order to make the light intensity higher than Imin 2 / Imax is not less than 0.71, and the normalized line width Δλ / ((λL-λS) / (N-1)) is preferably not less than 1 and not more than 2.5.

[0341] By determining the above-mentioned coefficients Dmin, Dmax and D according to the preferred range of the normalized spectral line width Δλ / ((λL-λS) / (N-1)), the target minimum spectral line width Δλmin, the target maximum spectral line width Δλmax and the target spectral line width Δλt can be determined.

[0342] 5.2 Controlling the wavelength into a triangular wave

[0343] Figure 36 to Figure 43 Shown as Fig. 9 The moving cumulative spectrum waveform is shown when the wavelength is controlled to be a triangular wave. Figure 36 to Figure 43 In the figure, the horizontal axis shows the wavelength and the vertical axis shows the light intensity. Figure 36 to Figure 43 In all cases, the number of irradiation pulses N is set to 30, and the wavelength difference between the shortest wavelength λS and the longest wavelength λL is set to 5 pm. Figure 36 to Figure 43 In , the line widths Δλ are different from each other. Fig.36 In the spectrum, the line width Δλ is 0.2pm. Fig.37 In the spectrum, the line width Δλ is 0.3 pm. Fig.38 In the spectrum, the line width Δλ is 0.4 pm. Fig.39 In the spectrum, the line width Δλ is 0.5 pm. Fig.40 In the spectrum, the line width Δλ is 0.6 pm. Fig.41 In the spectrum, the line width Δλ is 0.8 pm. Fig.42 In the spectrum, the line width Δλ is 1.0 pm. Fig.43 In the spectrum, the line width Δλ is 1.2 pm.

[0344] like Figure 36 to Figure 38As shown, the smaller the line width Δλ is, the steeper the peak corresponding to each pulse in the moving cumulative spectrum waveform becomes. Conversely, the larger the line width Δλ is, the more the steepness of the peak corresponding to each pulse in the moving cumulative spectrum waveform is relaxed.

[0345] exist Figure 36 to Figure 38 In the figure, the maximum intensity Imax and the minimum intensity Imin of the flat top area are shown respectively. Figure 39 to Figure 43 The illustration of the maximum intensity Imax and the minimum intensity Imin is omitted.

[0346] like Figure 39 to Figure 43 As shown in FIG. 1 , when the line width Δλ is further increased, the wavelength region near the average wavelength in the moving cumulative spectrum waveform becomes roughly flat. However, as the line width Δλ increases, the inclination in the wavelength region near the shortest wavelength λS and the longest wavelength λL in the moving cumulative spectrum waveform becomes gentle, and sometimes it cannot be said to be a preferred flat-top shape.

[0347] Fig.44 It is shown as Fig. 9 FIG. 4 is a graph showing the relationship between the line width Δλ and the light intensity ratio Imin / Imax when the wavelength is controlled to be in a triangular wave shape. Fig.44 In addition to the spectral line width Δλ, the horizontal axis also shows the normalized spectral line width Δλ / ((λL-λS) / (N / 2-1)). The normalized spectral line width Δλ / ((λL-λS) / (N / 2-1)) is a parameter obtained by dividing the spectral line width Δλ by the wavelength difference between peaks (λL-λS) / (N / 2-1).

[0348] In order to obtain stable exposure performance, the light intensity ratio Imin / Imax is preferably 0.71 or more, more preferably 0.90 or more.

[0349] In order to make the light intensity ratio Imin / Imax greater than or equal to 0.71, the normalized line width Δλ / ((λL-λS) / (N / 2-1)) is preferably greater than or equal to 1. In order to make the light intensity ratio Imin / Imax greater than or equal to 0.90, the normalized line width Δλ / ((λL-λS) / (N / 2-1)) is preferably greater than or equal to 1.2.

[0350] When the wavelength is controlled to be a triangular wave, the line width Δλ and the light intensity ratio Imin 2 The relationship between / Imax is not shown in the figure, but Fig.35 Similarly to the above description, it is preferable that the normalized line width Δλ / ((λL-λS) / (N / 2-1)) is 2.5 or less.

[0351] By determining the above-mentioned coefficients Dmin, Dmax and D according to the preferred range of the normalized spectral line width Δλ / ((λL-λS) / (N / 2-1)), the target minimum spectral line width Δλmin, the target maximum spectral line width Δλmax and the target spectral line width Δλt can be determined.

[0352] 6. Others

[0353] The above description is not limiting but simply illustrative. Therefore, those skilled in the art will appreciate that changes can be made to the embodiments of the present disclosure without departing from the claims. In addition, those skilled in the art will appreciate that the embodiments of the present disclosure can be used in combination.

[0354] Unless explicitly stated otherwise, the terms used in this specification and claims as a whole should be interpreted as "non-limiting" terms. For example, terms such as "including", "having", "having", and "having" should be interpreted as "excluding the existence of structural elements other than the structural elements to be recorded". In addition, the modifier "one" should be interpreted as meaning "at least one" or "one or more". In addition, terms such as "at least one of A, B, and C" should be interpreted as "A", "B", "C", "A+B", "A+C", "B+C", or "A+B+C". Furthermore, it should be interpreted as also including combinations of them and parts other than "A", "B", and "C".

Claims

1. A laser device, comprising: A narrowband device including a first actuator for adjusting an oscillation wavelength of a pulsed laser; A line width adjuster as a second actuator, which adjusts the line width of the pulsed laser; and processor, The processor reads data specifying the number of irradiation pulses of the pulsed laser irradiated to one portion of the irradiated object and the difference between the shortest wavelength and the longest wavelength, and determines a target spectral line width in such a manner that the spectral line width increases as the wavelength difference between a plurality of peaks of a moving cumulative spectrum waveform per the number of irradiation pulses of the pulsed laser increases. The processor controls the second actuator according to the target spectral line width. The processor controls the first actuator so that the oscillation wavelength changes periodically between the shortest wavelength and the longest wavelength per the number of irradiation pulses. The processor thereby relaxes the sharpness of the peak in the moving cumulative spectrum waveform so that the moving cumulative spectrum waveform approaches a flat-top shape.

2. The laser device according to claim 1, wherein: The laser device further includes an optical shutter arranged on the optical path of the pulse laser. The processor determines a target minimum spectral line width as the target spectral line width, The processor closes the shutter, controls the second actuator so that the line width gradually increases, and opens the shutter after the measured value of the line width becomes equal to or larger than the target minimum line width.

3. The laser device according to claim 1, wherein: The laser device further includes an optical shutter arranged on the optical path of the pulse laser. The processor determines a target minimum spectral line width and a target maximum spectral line width as the target spectral line width, The processor closes the shutter, controls the second actuator so that the line width changes, and opens the shutter after the measured value of the line width becomes greater than or equal to the target minimum line width and less than or equal to the target maximum line width.

4. The laser device according to claim 1, wherein: The processor determines the target spectral line width in the following manner: compared with the target spectral line width when the difference is the first value and the number of irradiation pulses is the second value, the target spectral line width becomes a larger value when the difference is the third value larger than the first value and the number of irradiation pulses is the fourth value less than the second value.

5. The laser device according to claim 1, wherein: The processor determines the target spectral line width in the following manner: compared with the target spectral line width when the difference is the first value and the number of irradiation pulses is the second value, the target spectral line width when the difference is the third value greater than the first value and the number of irradiation pulses is the fourth value smaller than the second value becomes a larger value.

6. The laser device according to claim 1, wherein: The processor determines the target line width so that the line width increases as a value obtained by dividing the difference by a value obtained by subtracting 1 from the number of irradiation pulses increases.

7. The laser device according to claim 1, wherein: The processor determines the target spectral line width such that the spectral line width increases as a value obtained by dividing the difference by a value obtained by dividing the number of irradiation pulses by 2 and subtracting 1 increases.

8. The laser device according to claim 1, wherein: The processor determines the target spectral line width so that a light intensity ratio obtained by dividing a minimum intensity of a flat-top region in the moving cumulative spectrum waveform by a maximum intensity of the flat-top region becomes equal to or greater than 0.

71.

9. The laser device according to claim 8, wherein: The minimum intensity is the minimum value of light intensity in the wavelength region from a value obtained by adding the spectral line width to the shortest wavelength to a value obtained by subtracting the spectral line width from the longest wavelength in the moving integrated spectrum waveform.

10. The laser device according to claim 8, wherein: The minimum intensity is a minimum value of light intensity in a wavelength range from the shortest wavelength to the longest wavelength in the moving integrated spectrum waveform.

11. The laser device according to claim 8, wherein: The processor determines the target spectral line width so that the light intensity ratio becomes equal to or greater than 0.

90.

12. The laser device according to claim 1, wherein: The processor determines the target line width so that a parameter obtained by dividing the line width by the wavelength difference between the peaks becomes equal to or greater than 1.

13. The laser device according to claim 12, wherein: The processor determines the target line width so that the parameter becomes equal to or less than 2.

5.

14. The laser device according to claim 12, wherein: The processor determines the target line width so that the parameter becomes equal to or greater than 1.

2.

15. The laser device according to claim 1, wherein: The processor determines the target line width so that a parameter obtained by dividing the line width by a value obtained by dividing the difference by a value obtained by subtracting 1 from the number of irradiation pulses becomes equal to or greater than 1.

16. The laser device according to claim 15, wherein: The processor determines the target line width so that the parameter becomes equal to or less than 2.

5.

17. The laser device according to claim 1, wherein: The processor determines the target line width so that a parameter obtained by dividing the line width by a value obtained by dividing the difference by the value obtained by subtracting 1 from the number of irradiation pulses divided by 2 becomes equal to or greater than 1.

18. The laser device according to claim 17, wherein: The processor determines the target line width so that the parameter becomes equal to or less than 2.

5.

19. A method for manufacturing an electronic device, comprising the following steps: Generate pulsed laser light through a laser device, outputting the pulse laser to an exposure device, exposing the pulsed laser on a photosensitive substrate in the exposure device to manufacture the electronic device, The laser device has: A narrowband device comprising a first actuator for adjusting an oscillation wavelength of the pulsed laser; A line width adjuster as a second actuator, which adjusts the line width of the pulsed laser; and processor, The processor reads data specifying the number of irradiation pulses of the pulsed laser irradiated to one portion of the irradiated object and the difference between the shortest wavelength and the longest wavelength, and determines a target spectral line width in such a manner that the spectral line width increases as the wavelength difference between a plurality of peaks of a moving cumulative spectrum waveform per the number of irradiation pulses of the pulsed laser increases. The processor controls the second actuator according to the target spectral line width. The processor controls the first actuator so that the oscillation wavelength changes periodically between the shortest wavelength and the longest wavelength per the number of irradiation pulses. The processor thereby relaxes the sharpness of the peak in the moving cumulative spectrum waveform so that the moving cumulative spectrum waveform approaches a flat-top shape.

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