Narrow-band gas laser device, wavelength control method, and method for manufacturing electronic device

Abstract

A narrow-band gas laser device has an actuator that changes a center wavelength of pulsed laser light, and a processor that controls the actuator, the processor reading in parameters including a number of irradiation pulses of the pulsed laser light that is irradiated to one site of an irradiation target, a shortest wavelength, and a longest wavelength, setting a first mode in which the center wavelength is changed in a manner that approaches from the shortest wavelength to the longest wavelength, and a second mode in which the center wavelength is changed in a manner that approaches from the longest wavelength to the shortest wavelength, in a manner that at least one of the first mode and the second mode is different between a case where the number of irradiation pulses is even and a case where the number of irradiation pulses is odd, and controls the actuator in a manner that the first mode and the second mode are alternately performed.

Description

TECHNICAL FIELD

[0001] The present application relates to a narrow-band gas laser device, a wavelength control method, and a method for manufacturing electronic devices. BACKGROUND

[0002] With the miniaturization and high integration of semiconductor integrated circuits, an improvement in resolution is required in a semiconductor exposure device. Hereinafter, the semiconductor exposure device will be simply referred to as "exposure device". Therefore, shortening of the wavelength of light output from an exposure light source has been progressing. In the exposure light source, a gas laser device is used instead of a conventional mercury lamp. Currently, as the gas laser device for exposure, a KrF excimer laser device which outputs ultraviolet light having a wavelength of 248 nm, and an ArF excimer laser device which outputs ultraviolet light having a wavelength of 193 nm are used.

[0003] As a current exposure technique, the following immersion exposure has been practically used: in the immersion exposure, a liquid is filled in a gap between a projection lens on the side of an exposure device and a wafer, and by changing the refractive index of the gap, the wavelength exhibited by an exposure light source is shortened. In the case where the ArF excimer laser device is used as the exposure light source to perform the immersion exposure, ultraviolet light having a wavelength of 134 nm in water is irradiated to the wafer. This technique is called ArF immersion exposure. The ArF immersion exposure is also called ArF immersion lithography.

[0004] The spectral line width at the time of natural oscillation of the KrF, ArF excimer laser device is wide, about 350 to 400 pm, and therefore, chromatic aberration of laser (ultraviolet light) which is reduced and projected onto the wafer through the projection lens on the side of the exposure device occurs, and the resolution is reduced. Therefore, it is necessary to narrow the spectral line width of laser output from the gas laser device to the extent that the chromatic aberration can be ignored. The spectral line width is also called spectral width. Therefore, a line narrow module having a narrow-band element is provided in the laser resonator of the gas laser device, and the spectral width is narrowed by the line narrow module. In addition, the narrow-band element can be an etalon, a grating, or the like. The laser device whose spectral width is narrowed like this is called a narrow-band laser device.

[0005] PRIOR ART DOCUMENTS

[0006] PATENT DOCUMENTS

[0007] Patent Document 1: US Patent Application Publication No. 2009 / 0147231 Specification

[0008] Patent Document 2: US Patent Application Publication No. 2002 / 0167975 Specification

[0009] Patent Document 3: US Patent Application Publication No. 2005 / 0083983 Specification

[0010] Patent Literature 4: Japanese Patent Application Laid-Open No. 07-058393

[0011] Patent Literature 5: International Publication No. 2019 / 079010 SUMMARY

[0012] The narrowband gas laser device of one aspect of the present application has an actuator that changes a center wavelength of pulsed laser light, and a processor that controls the actuator, the processor reading in parameters including a number of irradiation pulses of the pulsed laser light that is irradiated to one site of an irradiated object, a shortest wavelength, and a longest wavelength, setting a first mode and a second mode in such a manner that at least one of the first mode and the second mode differs between a case where the number of irradiation pulses is even and a case where the number of irradiation pulses is odd, and controlling the actuator in such a manner that the first mode and the second mode are alternately performed, the first mode being a mode in which the center wavelength is changed in such a manner as to approach from the shortest wavelength to the longest wavelength, and the second mode being a mode in which the center wavelength is changed in such a manner as to approach from the longest wavelength to the shortest wavelength.

[0013] The wavelength control method of one aspect of the present application controls a center wavelength of pulsed laser light that is output from a narrowband gas laser device, the wavelength control method including the steps of reading in parameters including a number of irradiation pulses of the pulsed laser light that is irradiated to one site of an irradiated object, a shortest wavelength, and a longest wavelength, and setting a first mode and a second mode in such a manner that at least one of the first mode and the second mode differs between a case where the number of irradiation pulses is even and a case where the number of irradiation pulses is odd, and controlling an actuator that changes the center wavelength in such a manner that the first mode and the second mode are alternately performed, the first mode being a mode in which the center wavelength is changed in such a manner as to approach from the shortest wavelength to the longest wavelength, and the second mode being a mode in which the center wavelength is changed in such a manner as to approach from the longest wavelength to the shortest wavelength.

[0014] The manufacturing method of an electronic device of one aspect of the present invention includes the steps of generating pulsed laser light by a narrowband gas laser device, outputting the pulsed laser light to an exposure device, and causing the pulsed laser light to be exposed on a photosensitive substrate in the exposure device to manufacture an electronic device, the narrowband gas laser device having an actuator that changes a center wavelength of the pulsed laser light and a processor that controls the actuator, the processor reading in parameters including a number of irradiation pulses of the pulsed laser light irradiated to one site of an irradiated object, a shortest wavelength, and a longest wavelength, setting a first mode and a second mode in such a manner that at least one of the first mode and the second mode differs between a case where the number of irradiation pulses is even and a case where the number of irradiation pulses is odd, and controlling the actuator in such a manner that the first mode and the second mode are alternately performed, the first mode being a mode in which the center wavelength is changed in such a manner as to approach from the shortest wavelength to the longest wavelength, and the second mode being a mode in which the center wavelength is changed in such a manner as to approach from the longest wavelength to the shortest wavelength. BRIEF DESCRIPTION OF DRAWINGS

[0015] Hereinafter, several embodiments of the present invention will be described only by way of example with reference to the attached drawings.

[0016] Figure 1 The structure of an exposure system in a comparative example is schematically shown.

[0017] Figure 2A and Figure 2B The structure of a narrowband gas laser device in a comparative example is schematically shown.

[0018] Figures 3A-3C A condition in which the position of a scan field SF of an irradiated object is changed with respect to the position of pulsed laser light is shown.

[0019] Figure 4 is a graph showing the periodic wavelength change in the comparative example.

[0020] Figure 5 is a graph showing Figure 4 the moving average every 30 pulses in the wavelength change shown in

[0021] Figure 6 is a graph showing Figure 4 the cumulative spectrum of 30 pulses in the wavelength change shown in

[0022] Figure 7 is a graph showing Figure 4 the moving average every 31 pulses in the wavelength change shown in

[0023] Figure 8 is a graph showing Figure 4 the cumulative spectrum of 31 pulses from the first to the 31st in the wavelength change shown in

[0024] Figure 9 is a graph showing the cumulative spectrum of 31 pulses from the 8th to the 38th of the wavelength change shown in Figure 4

[0025] Figure 10 The structure of the exposure system in the first embodiment is shown schematically.

[0026] Figure 11 is a flowchart showing the processing sequence of the wavelength control by the laser control processor.

[0027] Figure 12 is a flowchart showing the processing sequence of the wavelength control in the case where the number N of irradiation pulses is even in the first embodiment.

[0028] Figure 13 is a flowchart showing the processing sequence of the wavelength control in the case where the number N of irradiation pulses is even in the first embodiment.

[0029] Figure 14A is a graph showing the wavelength change set in the case where the number N of irradiation pulses is even in the first embodiment. Figure 14B is a graph showing the progress of the amount of wavelength change in the case where the number N of irradiation pulses is even in the first embodiment. Figure 14C is a graph showing the cumulative spectrum of 30 pulses of the wavelength change shown in Figure 14A

[0030] Figure 15 is a flowchart showing the processing sequence of the wavelength control in the case where the number N of irradiation pulses is odd in the first embodiment.

[0031] Figure 16 is a flowchart showing the processing sequence of the wavelength control in the case where the number N of irradiation pulses is odd in the first embodiment.

[0032] Figure 17A is a graph showing the wavelength change set in the case where the number N of irradiation pulses is odd in the first embodiment. Figure 17B is a graph showing the progress of the amount of wavelength change in the case where the number N of irradiation pulses is odd in the first embodiment. Figure 17C is a graph showing the cumulative spectrum of 31 pulses of the wavelength change shown in Figure 17A

[0033] Figure 18 is a flowchart showing the processing sequence of the wavelength control in the case where the number N of irradiation pulses is even in the second embodiment.

[0034] Figure 19 ​​​is a flowchart showing a processing sequence of the wavelength control in the case where the number N of irradiation pulses is even in the second embodiment.

[0035] Figure 20A is a graph showing the wavelength change set in the case where the number N of irradiation pulses is even in the second embodiment. Figure 20B is a graph showing the progress of the wavelength change amount in the case where the number N of irradiation pulses is even in the second embodiment. Figure 20C is a graph showing the cumulative spectrum of 30 pulses in the wavelength change shown in Figure 20A

[0036] Figure 21 is a flowchart showing a processing sequence of the wavelength control in the case where the number N of irradiation pulses is odd in the third embodiment.

[0037] Figure 22 is a flowchart showing a processing sequence of the wavelength control in the case where the number N of irradiation pulses is odd in the third embodiment.

[0038] Figure 23A is a graph showing the wavelength change set in the case where the number N of irradiation pulses is odd in the third embodiment. Figure 23B is a graph showing the progress of the wavelength change amount in the case where the number N of irradiation pulses is odd in the third embodiment. Figure 23C is a graph showing the cumulative spectrum of 31 pulses in the wavelength change shown in Figure 23A DETAILED DESCRIPTION

[0039] <CONTENT>

[0040] 1. COMPARATIVE EXAMPLE

[0041] 1.1 Exposure system

[0042] 1.1.1 Configuration

[0043] 1.1.2 Operation

[0044] 1.2 Narrowband gas laser device

[0045] 1.2.1 Configuration

[0046] 1.2.2 Operation

[0047] 1.3 Narrowband device

[0048] 1.3.1 Configuration

[0049] 1.3.2 Operation

[0050] 1.4 Number N of irradiation pulses

[0051] ​​1.5 Examples of wavelength variation of periodicity

[0052] 1.6 Problem of comparative example

[0053] 2. Laser device that sets wavelength variation pattern according to number N of irradiation pulses

[0054] 2.1 Configuration

[0055] 2.2 Main flow

[0056] 2.3 Case where number N of irradiation pulses is even

[0057] 2.4 Specific example of wavelength variation

[0058] 2.5 Case where number N of irradiation pulses is odd

[0059] 2.6 Specific example of wavelength variation

[0060] 2.7 Effects

[0061] 3. Modified example of case where number N of irradiation pulses is even

[0062] 3.1 Operation

[0063] 3.2 Specific example of wavelength variation

[0064] 3.3 Effects

[0065] 4. Modified example of case where number N of irradiation pulses is odd

[0066] 4.1 Operation

[0067] 4.2 Specific example of wavelength variation

[0068] 4.3 Effects

[0069] 5. Others

[0070] Embodiments of the present application will be described below in detail with reference to the accompanying drawings. The embodiments described below show several examples of the present application and do not limit the scope of the present application. Furthermore, the configuration and operation described in each embodiment are not necessarily all essential to the present application. In addition, the same reference numerals are assigned to the same structural elements and repeated description is omitted.

[0071] 1. Comparative example

[0072] 1.1 Exposure system

[0073] Figure 1 The configuration of the exposure system in the comparative example is schematically shown. The comparative example of the present application is a mode that the applicant recognizes as known only to the applicant and is not a publicly known example that the applicant himself acknowledges.

[0074] The exposure system includes a narrow-band gas laser device 100 and an exposure device 200. In Figure 1 The narrow-band gas laser device 100 is shown schematically.

[0075] The narrow-band gas laser device 100 includes a laser control processor 130. The narrow-band gas laser device 100 is configured to output pulsed laser light toward the exposure device 200.

[0076] 1.1.1 Configuration

[0077] As shown in Figure 1 , the exposure device 200 includes an illumination optical system 201, a projection optical system 202, and an exposure control processor 210.

[0078] The illumination optical system 201 illuminates a reticle pattern of an unillustrated reticle arranged on a reticle stage RT with pulsed laser light emitted from the narrow-band gas laser device 100.

[0079] The projection optical system 202 reduces and projects the pulsed laser light that has passed through the reticle, so as to form an image on an unillustrated workpiece arranged on a workpiece stage WT. The workpiece is a photosensitive substrate such as a semiconductor wafer on which a resist film is coated.

[0080] The exposure control processor 210 controls the exposure device 200 as a whole, and transmits and receives various parameters and various signals with the laser control processor 130.

[0081] 1.1.2 Operation

[0082] The exposure control processor 210 transmits various parameters including the shortest wavelength λS and the longest wavelength λL, the number of irradiation pulses N, and a trigger signal to the laser control processor 130. The laser control processor 130 controls the narrow-band gas laser device 100 in accordance with these parameters and the signal.

[0083] The exposure control processor 210 causes the reticle stage RT and the workpiece stage WT to move in mutually opposite directions in parallel in synchronization. Thereby, the workpiece is exposed to the pulsed laser light that reflects the reticle pattern.

[0084] Through this exposure process, the reticle pattern is transferred onto the semiconductor wafer. Then, by going through a plurality of processes, an electronic device can be manufactured.

[0085] 1.2 Narrow-band gas laser device

[0086] 1.2.1 Configuration

[0087] Figure 2A and Figure 2BThe structure of the narrowband gas laser device in the comparative example is shown schematically. In each figure, a V-axis, an H-axis, and a Z-axis perpendicular to each other are shown. Figure 2A A narrowband gas laser device 100 viewed in the -V direction is shown, Figure 2B A narrowband gas laser device 100 viewed in the -H direction is shown.

[0088] The narrowband gas laser device 100 includes, in addition to the laser control processor 130, a laser cavity 10, a narrowband device 14, and an output coupling mirror 15. The narrowband device 14 and the output coupling mirror 15 constitute an optical resonator.

[0089] The laser cavity 10 is disposed on an optical path of the optical resonator. Windows 10a and 10b are provided in the laser cavity 10.

[0090] The laser cavity 10 has a pair of electrodes 11a and 11b inside and houses a laser gas as a laser medium. The laser medium is, for example, F2, ArF, KrF, XeCl, or XeF.

[0091] The -V direction and the +V direction coincide with the directions in which the electrodes 11a and 11b face. The -Z direction coincides with the direction of travel of the light beam emitted from the window 10a. The +Z direction coincides with the direction of travel of the pulsed laser light emitted from the window 10b and output via the output coupling mirror 15.

[0092] The narrowband device 14 includes first and second prisms 41 and 42 and a grating 53. Details of the narrowband device 14 are described later.

[0093] The output coupling mirror 15 is constituted by a partial mirror.

[0094] 1.2.2 Action

[0095] The laser control processor 130 acquires various parameters including the shortest wavelength λS and the longest wavelength λL as target values of the wavelength and the number of irradiation pulses N from the exposure control processor 210. The laser control processor 130 sends a control signal to the narrowband device 14 in accordance with the shortest wavelength λS and the longest wavelength λL and the number of irradiation pulses N.

[0096] 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 a pulse power module not shown. The pulse power module generates a high voltage in a pulse shape when receiving the oscillation trigger signal, and applies the high voltage to the electrodes 11a and 11b.

[0097] When high voltage is applied to the electrodes 11a and 11b, discharge is caused between the electrodes 11a and 11b. By the energy of this discharge, the laser gas in the laser cavity 10 is excited to transition to a high energy level. Then, when the excited laser gas transitions to a low energy level, light of a wavelength corresponding to the difference between the energy levels is emitted.

[0098] The light generated in the laser cavity 10 is emitted to the outside of the laser cavity 10 via the windows 10a and 10b. The light emitted from the window 10a is incident on the narrowbanding device 14 as a light beam. The light in the vicinity of the desired wavelength among the light incident on the narrowbanding device 14 is returned to the laser cavity 10 by being reflected by the narrowbanding device 14.

[0099] The output coupling mirror 15 transmits and outputs a part of the light emitted from the window 10b and reflects the other part to return to the laser cavity 10.

[0100] Thus, the light emitted from the laser cavity 10 reciprocates between the narrowbanding 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 is reflected by the narrowbanding device 14 to become light having a wavelength distribution that is a steep wavelength distribution with a part of the range of the selected wavelength of the narrowbanding device 14 as the center wavelength. The light obtained by performing laser oscillation and narrowbanding like this is output from the output coupling mirror 15 as pulsed laser light. The wavelength of the pulsed laser light refers to the center wavelength unless otherwise specified.

[0101] The pulsed laser light output from the narrowbanding gas laser device 100 is incident on the exposure device 200.

[0102] 1.3 Narrowbanding device

[0103] 1.3.1 Configuration

[0104] The first prism 41 is disposed on the optical path of the light beam emitted from the window 10a. The first prism 41 is supported by a holder 411.

[0105] The second prism 42 is disposed on the optical path of the light beam after passing through the first prism 41. The second prism 42 is supported by a holder 421.

[0106] The first and second prisms 41 and 42 are composed of a material such as calcium fluoride or synthetic quartz that has high transmittance with respect to the selected wavelength of the narrowbanding device 14.

[0107] The first and second prisms 41 and 42 are configured so that the surfaces through which the light beams are emitted are parallel to the V-axis. The first and second prisms 41 and 42 are each rotatable about an axis parallel to the V-axis by a rotation stage 412 and 422. Here, as an example of the rotation stages 412 and 422, a rotation stage having high responsiveness by a piezoelectric element is cited.

[0108] The grating 53 is disposed on the optical path of the light beams after passing through the second prism 42. The direction of the grooves of the grating 53 coincides with the direction of the V-axis.

[0109] The grating 53 is supported by a holder 531.

[0110] 1.3.2 Operation

[0111] The light beams emitted from the window 10a change the traveling direction in a plane parallel to the HZ plane, which is a plane perpendicular to the V-axis, by the first and second prisms 41 and 42, and the beam width is enlarged in the plane parallel to the HZ plane. As an example, the traveling direction of the light beams traveling toward the grating 53 by both the first and second prisms 41 and 42 substantially coincides with the -Z direction.

[0112] The light emitted from the second prism 42 to the grating 53 is reflected by the plurality of grooves of the grating 53, and diffracted in a direction corresponding to the wavelength of the light. Thus, the light reflected by the plurality of grooves of the grating 53 is dispersed in a plane parallel to the HZ plane. The grating 53 is disposed in a Littrow configuration so that the incident angle of the light beams emitted from the second prism 42 to the grating 53 coincides with the diffraction angle of the diffracted light of the desired wavelength.

[0113] The second prism 42 and the first prism 41 reduce the beam width of the light returned from the grating 53 in a plane parallel to the HZ plane, and return the light into the laser cavity 10 via the window 10a.

[0114] The rotation stages 412 and 422 are controlled by the laser control processor 130.

[0115] When the first prism 41 is slightly rotated by the rotation stage 412, the traveling direction of the light beams emitted from the first prism 41 toward the grating 53 is slightly changed in a plane parallel to the HZ plane. Thus, the incident angle of the light beams emitted from the second prism 42 to the grating 53 is slightly changed. Thus, the selected wavelength of the narrowbanding device 14 is changed.

[0116] When the second prism 42 is slightly rotated by the rotation stage 422, the traveling direction of the light beams emitted from the second prism 42 toward the grating 53 is slightly changed in a plane parallel to the HZ plane. Thus, the incident angle of the light beams emitted from the second prism 42 to the grating 53 is slightly changed. Thus, the selected wavelength of the narrowbanding device 14 is changed.

[0117] The laser control processor 130 controls the rotation stage 412 of the first prism 41 in accordance with the shortest wavelength λS received from the exposure control processor 210.

[0118] The laser control processor 130 controls the rotation stage 422 of the second prism 42 in such a manner that the second prism 42 is rotated by a little every time the pulsed laser is output. Thereby, the selection wavelength of the narrowbanding device 14 is lengthened by a little every 1 pulse. The rotation stage 422 includes an actuator in the present application.

[0119] After the selection wavelength reaches the longest wavelength λL received from the exposure control processor 210, the laser control processor 130 controls the rotation stage 422 in such a manner that the second prism 42 is rotated by a little in the opposite direction. Thereby, the selection wavelength of the narrowbanding device 14 is shortened by a little every 1 pulse.

[0120] After the selection wavelength returns to the shortest wavelength λS, the laser control processor 130 again lengthens the selection wavelength by a little.

[0121] Thus, the laser control processor 130 controls the rotation stage 422 in such a manner that the posture of the second prism 42 is changed every 1 pulse and is changed periodically every a plurality of pulses. Thereby, the wavelength of the pulsed laser is changed in a plurality of stages between the shortest wavelength λS and the longest wavelength λL and is changed periodically every a plurality of pulses.

[0122] The focal length in the exposure device 200 (refer to Figure 1 ) depends on the wavelength of the pulsed laser. The pulsed laser output from the narrowbanding gas laser device 100 by the multi-wavelength oscillation can be imaged at a plurality of different positions in the direction of the optical path axis of the pulsed laser, and the depth of focus can be substantially increased. For example, even in the case where a resist film having a large thickness is exposed, the imaging performance in the thickness direction of the resist film can be maintained.

[0123] 1.4 Number N of irradiation pulses

[0124] Figures 3A-3C The situation in which the position of the scan field SF of the irradiated object changes with respect to the position of the pulsed laser is shown. The irradiated object is, for example, a semiconductor wafer. The scan field SF of the semiconductor wafer corresponds, for example, to an area in which a number of semiconductor chips formed in the semiconductor wafer are formed. The scan field SF is coated with a resist film. The width in the X-axis direction of the scan field SF is the same as the width in the X-axis direction of the beam cross section B of the pulsed laser at the position of the irradiated object. The width in the Y-axis direction of the scan field SF is larger than the width W in the Y-axis direction of the beam cross section B of the pulsed laser at the position of the irradiated object.

[0125] The order of exposure of the scan field SF by the pulsed laser is performed in the order of Figure 3A , Figure 3B , Figure 3C . First, as shown in Figure 3A , the workpiece table WT is positioned so that the position of the pulsed laser coincides with one end in the Y-axis direction of the scan field SF, and exposure is started. Next, as shown in Figure 3B , the workpiece table WT is moved so that the position of the scan field SF changes at a speed V with respect to the position of the pulsed laser. As shown in Figure 3C , the workpiece table WT is moved until the position of the pulsed laser coincides with the other end in the Y-axis direction of the scan field SF, and exposure of the scan field SF is ended. In this way, exposure is performed while the position of the scan field SF is moved with respect to the position of the pulsed laser.

[0126] The required time T for the scan field SF to move a distance equivalent to the width W of the beam section B of the pulsed laser at the speed V is as follows.

[0127] T = W / V

[0128] The number N of irradiation pulses of the pulsed laser irradiated to any one part of the scan field SF is the same as the number of pulses of the pulsed laser generated in the required time T, as follows.

[0129] N = F · T

[0130] = F · W / V

[0131] Here, F is the repetition frequency of the pulsed laser.

[0132] The number N of irradiation pulses is also referred to as the number of N-seam pulses.

[0133] 1.5 Example of periodic wavelength variation

[0134] Figure 4 is a graph showing the periodic wavelength variation in the comparative example. In Figure 4 , the horizontal axis shows the pulse number n, and the vertical axis shows the wavelength λ.

[0135] In Figure 4In the example shown, the wavelength λ changes periodically every 30 pulses between the shortest wavelength λs and the longest wavelength λL. Specifically, during a period in which 15 pulses from the 1st (n = 1) to the 15th (n = 15) are generated, the wavelength λ changes from the shortest wavelength λs to the longest wavelength λL in such a manner that it becomes longer every 1 pulse by a fixed wavelength change amount. Then, during a period in which 15 pulses from the 16th (n = 16) to the 30th (n = 30) are generated, the wavelength λ changes from the longest wavelength λL to the shortest wavelength λs in such a manner that it becomes shorter every 1 pulse by a certain wavelength change amount. Then, similarly, the operation of generating 15 pulses while making the wavelength longer and the operation of generating 15 pulses while making the wavelength shorter are repeated.

[0136] The average of the shortest wavelength λs and the longest wavelength λL is set to λ0.

[0137] Figure 5 is a graph showing Figure 4 The moving average every 30 pulses in the wavelength change shown. In Figure 5 , the horizontal axis shows the pulse number n, and the vertical axis shows the moving average every 30 pulses λavg. The moving average every 30 pulses λavg is expressed by the following equation.

[0138] λavg = (λ(n-29) + λ(n-28) +... + λ(n)) / 30

[0139] Here, λ(X) is the wavelength λ when the pulse number n is X. For example, the moving average λavg when the pulse number n is 30 corresponds to the arithmetic mean of the wavelengths λ of 30 pulses from the 1st (n = 1) to the 30th (n = 30).

[0140] In the wavelength change shown Figure 4 , the moving average every 30 pulses λavg is constant regardless of the value of the pulse number n, and coincides with Figure 4 the average λ0 shown.

[0141] The case where the moving average every 30 pulses λavg is constant has the following advantages. That is, in the case where the number of irradiation pulses N described with reference to Figures 3A-3C is 30 (N = 30), the 30 pulses irradiated to an arbitrary portion of the scan field SF of the irradiated object all have the same average wavelength. Due to this, the deviation of the exposure result due to the irradiation position is small, and it is possible to manufacture electronic devices of high quality.

[0142] Figure 6 is a graph showing Figure 4A graph of the cumulative spectrum of 30 pulses in the wavelength variation shown. In Figure 6 The horizontal axis indicates the wavelength λ, and the vertical axis indicates the light intensity. In Figure 4 The wavelength is made to vary in a plurality of stages between the shortest wavelength λS and the longest wavelength λL in the wavelength variation shown, and therefore, in Figure 6 A plurality of wavelength peaks appear between the shortest wavelength λS and the longest wavelength λL in the cumulative spectrum shown. As long as the light intensity of the 30 pulses is maintained substantially constant, the plurality of wavelength peaks shown become substantially the same light intensity, and it is possible to make the cumulative spectrum substantially flat in shape. Figure 6

[0143] 1.6 Problems of Comparative Examples

[0144] Figure 7 is a graph showing Figure 4 A graph of the moving average per 31 pulses in the wavelength variation shown. In Figure 7 The horizontal axis indicates the pulse number n, and the vertical axis indicates the moving average per 31 pulses λavg. The moving average per 31 pulses λavg is expressed by the following equation.

[0145] λavg = (λ(n-30) + λ(n-29) +... + λ(n)) / 31

[0146] In the wavelength variation shown, the 31st (n = 31) pulse of the shortest wavelength λS is added to the 31 pulses from the 1st (n = 1) to the 31st (n = 31) compared to the 30 pulses from the 1st (n = 1) to the 30th (n = 30). Therefore, the average value of the wavelength λ of the 31 pulses becomes a value smaller than λ0. Figure 4 Further, the 1st (n = 1) pulse of the shortest wavelength λS is excluded from the 31 pulses from the 2nd (n = 2) to the 32nd (n = 32) compared to the 31 pulses from the 1st (n = 1) to the 31st (n = 31). Therefore, the average value of the wavelength λ of the 31 pulses from the 2nd (n = 2) to the 32nd (n = 32) is slightly larger than that of the 31 pulses from the 1st (n = 1) to the 31st (n = 31).

[0147] As such, the moving average per 31 pulses λavg varies depending on how the consecutive 31 pulses are selected. Therefore, in the case where the number of irradiation pulses N described in the

[0148] The average wavelength differs depending on the irradiation position in the scan field SF in the case where the number of irradiation pulses N described in the Figures 3A-3C explanation is 31 (N = 31). In this case, a deviation occurs in the exposure result depending on the irradiation position, and it is possible to affect the quality of the electronic device.​

[0149] Figure 8 is a graph showing the cumulative spectrum of 31 pulses from the 1st (n = 1) to the 31st (n = 31) in the wavelength variation shown in Figure 4 In Figure 8 , the horizontal axis represents the wavelength λ, and the vertical axis represents the light intensity. With respect to 30 pulses from the 1st (n = 1) to the 30th (n = 30), the 31st (n = 31) pulse of the shortest wavelength λS is added to 31 pulses from the 1st (n = 1) to the 31st (n = 31), and thus a high peak appears near the shortest wavelength λS.

[0150] Figure 9 is a graph showing the cumulative spectrum of 31 pulses from the 8th (n = 8) to the 38th (n = 38) in the wavelength variation shown in Figure 4 In Figure 9 , the horizontal axis represents the wavelength λ, and the vertical axis represents the light intensity. With respect to 30 pulses from the 8th (n = 8) to the 37th (n = 37), the 38th (n = 38) pulse near the average wavelength λ0 is added to 31 pulses from the 8th (n = 8) to the 38th (n = 38), and thus a high peak appears near the average wavelength λ0.

[0151] As shown in Figure 8 and Figure 9 , in the wavelength variation shown in Figure 4 , sometimes the cumulative spectrum of 31 pulses cannot achieve a flat shape. In addition, the shape of the cumulative spectrum of 31 pulses differs depending on how the consecutive 31 pulses are selected, and depending on the irradiation position, a deviation occurs in the exposure result, which can affect the quality of electronic devices.

[0152] In several embodiments described below, the wavelength variation pattern is set in accordance with the number N of irradiation pulses of the pulsed laser irradiated to 1 site. Depending on whether the number N of irradiation pulses is even or odd, the wavelength variation pattern is different.

[0153] 2. Laser device in which the wavelength variation pattern is set in accordance with the number N of irradiation pulses

[0154] 2.1 Structure

[0155] Figure 10 The structure of the exposure system in the 1st embodiment is schematically shown. The laser control processor 130 included in the narrowband gas laser device 100 of the 1st embodiment is a processing device including a memory 132 in which a control program is stored and a CPU (central processing unit) 131 that executes the control program.

[0156] The exposure control processor 210 included in the exposure apparatus 200 is a processing device including a memory 212 in which a control program is stored and a CPU 211 that executes the control program.

[0157] The laser control processor 130 and the exposure control processor 210 are particularly configured or programmed to perform various processes included in the present application.

[0158] The laser control processor 130 is configured to set a wavelength variation pattern in accordance with the shortest wavelength λS and the longest wavelength λL and the number of irradiation pulses N.

[0159] As to other aspects, the structure of the first embodiment is the same as that of the comparative example.

[0160] The various parameters including the shortest wavelength λS and the longest wavelength λL and the number of irradiation pulses N are not limited to being received from the exposure control processor 210, but can be received from an external device. For example, the various parameters can be received from an unillustrated lithography control processor provided separately with respect to the exposure apparatus 200. The lithography control processor can be connected to a plurality of exposure control processors 210 included in a plurality of exposure apparatuses 200 provided in a semiconductor factory.

[0161] Alternatively, the exposure control processor 210 or the lithography control processor can read in the various parameters including the shortest wavelength λS and the longest wavelength λL and the number of irradiation pulses N, set a wavelength variation pattern, and output a target wavelength to the laser control processor 130. In this case, the exposure control processor 210 or the lithography control processor can perform the same processing as that of the laser control processor 130 described below.

[0162] 2.2 Main flow

[0163] Figure 11 is a flowchart showing the processing sequence of the wavelength control performed by the laser control processor 130. The laser control processor 130 sets a wavelength variation pattern and performs wavelength control through the following processing.

[0164] In S100, the laser control processor 130 reads in various parameters received from an external device such as the exposure control processor 210. The various parameters include the shortest wavelength λS, the longest wavelength λL, and the number of irradiation pulses N of the pulsed laser irradiated to one site.

[0165] Next, in S110, the laser control processor 130 determines whether the number of irradiation pulses N is even. In the case where the number of irradiation pulses N is even (S110: YES), the laser control processor 130 causes the processing to proceed to S120. In the case where the number of irradiation pulses N is odd (S110: NO), the laser control processor 130 causes the processing to proceed to S140.

[0166] In S120, the laser control processor 130 performs the wavelength control in the case where the number N of irradiation pulses is even. Details of S120 will be described later. Figure 12 and Figure 13 In S120, the laser control processor 130 performs the wavelength control in the case where the number N of irradiation pulses is even. Details of S120 will be described later.

[0167] In S140, the laser control processor 130 performs the wavelength control in the case where the number N of irradiation pulses is odd. Details of S140 will be described later. Figure 15 and Figure 16 In S140, the laser control processor 130 performs the wavelength control in the case where the number N of irradiation pulses is odd. Details of S140 will be described later.

[0168] In S160, the laser control processor 130 determines whether or not to end the wavelength control. In the case where the wavelength control is not ended (S160: No), the laser control processor 130 returns the process to S100. In the case where the wavelength control is ended (S160: Yes), the laser control processor 130 ends the process of the present flowchart.

[0169] 2.3 Case where the number N of irradiation pulses is even

[0170] Figure 12 and Figure 13 is a flowchart showing a process sequence of the wavelength control in the case where the number N of irradiation pulses is even in the 1st embodiment. Figure 12 and Figure 13 The process shown in FIG. 17 corresponds to the sub-step of S120 of FIG. 16. Figure 11

[0171] For example, in the case where the number N of irradiation pulses of the pulse laser irradiated to one site is 30 (N = 30), in the 1st embodiment, the wavelength variation pattern is set in the following manner.

[0172] The period of the variation of the wavelength is set to 30 pulses.

[0173] In the first 15 pulses of the 30 pulses, the 1st pattern of the wavelength variation in which the wavelength λ is varied in a manner of approaching from the shortest wavelength λS to the longest wavelength λL is performed (S122 to S127).

[0174] In the last 15 pulses of the 30 pulses, the 2nd pattern of the wavelength variation in which the wavelength λ is varied in a manner of approaching from the longest wavelength λL to the shortest wavelength λS is performed (S132 to S137).

[0175] First, in S121, the laser control processor 130 calculates the wavelength variation amount δλ1 by the following equation. The wavelength variation amount δλ1 is a value that specifies the wavelength variation amount per 1 pulse.​

[0176] δλ1= (λL- λS) / (N / 2- 1)

[0177] In a case where the number of irradiation pulses N is 30 (N = 30), the wavelength variation amount δλ1 becomes a value obtained by dividing the difference between the longest wavelength λL and the shortest wavelength λS by 14.

[0178] In the processes of S122 to S127 that follow, the wavelength variation of the 1st mode is performed.

[0179] In S122, the laser control processor 130 sets the counter i for counting the number of pulses to 1.

[0180] Next, in S123, the laser control processor 130 calculates the target wavelength λt by the following equation.

[0181] λt= λS+ (i- 1) · δλ1

[0182] The target wavelength λt in a case where the value of the counter i is 1 (i = 1) becomes the shortest wavelength λS.

[0183] The target wavelength λt increases by the wavelength variation amount δλ1 each time as the value of the counter i increases one by one.

[0184] Next, in S124, the laser control processor 130 controls the rotation stage 422 of the 2nd prism 42 in accordance with the target wavelength λt.

[0185] Next, in S125, the laser control processor 130 determines whether or not a laser pulse is output. It can be determined whether or not a laser pulse is output in accordance with whether or not the oscillation trigger signal is output by the laser control processor 130, or it can be determined whether or not a laser pulse is output in accordance with whether or not the laser pulse is detected by a not-illustrated light detector. In a case where a laser pulse is not output (S125: No), the laser control processor 130 stands by until a laser pulse is output. In a case where a laser pulse is output (S125: Yes), the laser control processor 130 causes the process to proceed to S126.

[0186] In S126, the laser control processor 130 determines whether or not the 1st mode is ended in accordance with whether or not the value of the counter i is N / 2 or more.

[0187] In a case where the number of irradiation pulses N is 30 (N = 30), if the value of the counter i does not reach 15, the output of the first 15 pulses out of the 30 pulses is not ended. Therefore, the laser control processor 130 determines that the 1st mode is not ended (S126: No), and causes the process to proceed to S127.

[0188] If the value of the counter i reaches 15, the output of the first 15 pulses has been completed. Therefore, the laser control processor 130 determines that the first mode is ended (S126: YES), and the process proceeds to Figure 13 S132.

[0189] In S127, the laser control processor 130 adds 1 to the value of the counter i, and returns to S123.

[0190] In Figure 13 the process of S132 to S137, the wavelength change of the second mode is performed.

[0191] In S132, the laser control processor 130 sets the counter i for counting the number of pulses to 1 again.

[0192] Next, in S133, the laser control processor 130 calculates the target wavelength λt by the following equation.

[0193] λt = λL - (i - 1) · δλ1

[0194] The target wavelength λt in the case where the value of the counter i is 1 (i = 1) becomes the longest wavelength λL.

[0195] With the value of the counter i increasing one by one, the target wavelength λt changes by the wavelength change amount -δλ1 each time, and the value of the target wavelength λt decreases.

[0196] The processes of S134 and S135 next are the same as those of Figure 12 S124 and S125, respectively.

[0197] Next, in S136, the laser control processor 130 determines whether or not the second mode is ended depending on whether or not the value of the counter i is N / 2 or more.

[0198] In the case where the number of irradiation pulses N is 30 (N = 30), if the value of the counter i does not reach 15, the output of the last 15 pulses out of 30 pulses is not ended. Therefore, the laser control processor 130 determines that the second mode is not ended (S136: NO), and the process proceeds to S137.

[0199] If the value of the counter i reaches 15, the output of the last 15 pulses has been completed. Therefore, the laser control processor 130 determines that the second mode is ended (S136: YES), and the process proceeds to Figure 13 S138.

[0200] In S137, the laser control processor 130 adds 1 to the value of the counter i, and returns to S133.

[0201] In S138, the laser control processor 130 determines whether or not the various parameters are changed. For example, in a case where new parameters such as the shortest wavelength λS and the longest wavelength λL are received from the exposure control processor 210, it is determined that the various parameters are changed.

[0202] In a case where the various parameters are changed (S138: Yes), the laser control processor 130 ends the processing of the present flowchart, and returns to the processing illustrated in FIG. 12. Figure 11

[0203] In a case where the various parameters are not changed (S138: No), the laser control processor 130 returns to S122 of FIG. 12. The processing of S122 to S138 of FIG. 12 is repeatedly performed, whereby the first mode and the second mode are alternately performed. Figure 12 Figure 13

[0204] 2.4 Specific example of wavelength variation

[0205] Figure 14A is a graph illustrating the wavelength variation set in a case where the number N of pulses to be irradiated is even in the first embodiment. In Figure 14A , the horizontal axis represents the pulse number n, and the vertical axis represents the wavelength λ.

[0206] The first mode of the wavelength variation includes 15 pulses from the first (n = 1) to the 15th (n = 15). The first mode starts from the shortest wavelength λS, and the wavelength is changed by the wavelength variation amount δλ1 at a time every 1 pulse, and finally becomes the longest wavelength λL.

[0207] The second mode of the wavelength variation includes 15 pulses from the 16th (n = 16) to the 30th (n = 30). The second mode starts from the longest wavelength λL, and the wavelength is changed by the wavelength variation amount -δλ1 at a time every 1 pulse, and finally becomes the shortest wavelength λS.

[0208] By thus setting the first mode and the second mode, the wavelength variation mode becomes a mode with a period of 30 pulses, and therefore, the moving average value every 30 pulses is constant regardless of how the 30 consecutive pulses are selected.

[0209] Figure 14B is a graph illustrating the passage of the wavelength variation amount in a case where the number N of pulses to be irradiated is even in the first embodiment. In Figure 14B , the horizontal axis represents the pulse number n, and the vertical axis represents the wavelength variation amount δλ.

[0210] In 14 pulses from the second (n = 2) to the 15th (n = 15), the wavelength variation amount δλ is constant, and is δλ1. That is, the wavelength λ is increased by δλ1 at a time every 1 pulse with respect to the previous pulse.​​​

[0211] In the 16th (n = 16) pulse, the wavelength variation amount δλ is 0. That is, the wavelength λ does not change with respect to the previous pulse.

[0212] In the 14 pulses from the 17th (n = 17) to the 30th (n = 30), the wavelength variation amount δλ is constant, -δλ1. That is, the wavelength λ changes by -δλ1 each time with respect to the previous pulse, and the value of the wavelength λ decreases.

[0213] In the 31st (n = 31) pulse, the wavelength variation amount δλ is 0. That is, the wavelength λ does not change with respect to the previous pulse.

[0214] In the 1st embodiment, in the case where the number of irradiation pulses N is even, the wavelength λ is repeatedly increased and decreased as described above.

[0215] Figure 14C is a graph showing the cumulative spectrum of the 30 pulses in the wavelength variation shown in Figure 14A In Figure 14C , the horizontal axis represents the wavelength λ, and the vertical axis represents the light intensity. In Figure 14A , the wavelength is caused to change in a plurality of stages between the shortest wavelength λs and the longest wavelength λL, and thus, in the cumulative spectrum shown in Figure 14C , a plurality of wavelength peaks appear between the shortest wavelength λs and the longest wavelength λL. As long as the light intensity of the 30 pulses is maintained substantially constant, the plurality of wavelength peaks shown in Figure 14C become substantially the same light intensity as each other, and it is possible to cause the cumulative spectrum to have a substantially flat shape.

[0216] 2.5 Case where the number of irradiation pulses N is odd

[0217] Figure 15 and Figure 16 is a flowchart showing the processing sequence of the wavelength control in the case where the number of irradiation pulses N is odd in the 1st embodiment. Figure 15 and Figure 16 the processing shown in Figure 11 corresponds to the sub-step of S140 of

[0218] For example, in the case where the number of irradiation pulses N of the pulsed laser irradiated to one site is 31 (N = 31), in the 1st embodiment, the wavelength variation pattern is set in the following manner.

[0219] The period of the variation of the wavelength is set to 31 pulses.

[0220] In the first 16 pulses of the 31 pulses, the 1st pattern of causing the wavelength λ to vary in a manner approaching from the shortest wavelength λs to the longest wavelength λL is performed.

[0221] In the last 15 of the 31 pulses, a second mode is performed, in which the wavelength λ changes in a manner that approaches the shortest wavelength λS from the longest wavelength λL.

[0222] First, in S141, the laser control processor 130 calculates the wavelength change δλ1 using the following formula.

[0223] δλ1=(λL-λS) / ((N-1) / 2)

[0224] When the number of irradiation pulses N is 31 (N=31), the wavelength change δλ1 is the value obtained by dividing the difference between the longest wavelength λL and the shortest wavelength λS by 15.

[0225] In the following processing steps S142 to S147, the wavelength of mode 1 is changed.

[0226] The processing of S142 to S145 is respectively with Figure 12 The processing of S122 to S125 is the same.

[0227] In S146, the laser control processor 130 determines whether the first mode has ended based on whether the value of counter i is greater than (N+1) / 2.

[0228] When the number of irradiation pulses N is 31 (N=31), if the value of counter i has not reached 16, the output of the first 16 pulses out of the 31 pulses has not ended. Therefore, the laser control processor 130 determines that the first mode has not ended (S146: No), and causes the process to proceed to S147.

[0229] If the value of counter i reaches 16, the output of the initial 16 pulses has been completed. Therefore, the laser control processor 130 determines that mode 1 has ended (S146: Yes), and initiates processing. Figure 16 S152.

[0230] In S147, the laser control processor 130 increments the value of counter i by 1 and returns to S143.

[0231] exist Figure 16 In the processing of S152 to S157, the wavelength of the second mode is changed.

[0232] In S152, the laser control processor 130 sets the counter i, which is used to count the number of pulses, back to 1.

[0233] Next, in S153, the laser control processor 130 calculates the target wavelength λt using the following formula.

[0234] λt=λL-(i-0.5)·δλ1

[0235] The target wavelength λt in the case where the value of the counter i is 1 (i = 1) becomes a value obtained by subtracting half of δλ1 from the longest wavelength λL.

[0236] The target wavelength λt is changed by the wavelength change amount -δλ1 each time as the value of the counter i increases one by one, and the value of the target wavelength λt decreases.

[0237] The processes of S154 and S155 next are the same as those of S124 and S125 of Figure 12 , respectively.

[0238] Next, in S156, the laser control processor 130 determines whether or not the second mode is ended depending on whether or not the value of the counter i is N / 2 or more.

[0239] In the case where the number of irradiation pulses N is 31 (N = 31), if the value of the counter i does not reach 15, the output of the last 15 pulses among the 31 pulses is not ended. Therefore, the laser control processor 130 determines that the second mode is not ended (S156: No), and the process proceeds to S157.

[0240] If the value of the counter i reaches 15, the output of the last 15 pulses is completed. Therefore, the laser control processor 130 determines that the second mode is ended (S156: Yes), and the process proceeds to S158 of Figure 13 .

[0241] In S157, the laser control processor 130 adds 1 to the value of the counter i, and returns to S153.

[0242] In S158, the laser control processor 130 determines whether or not the various parameters are changed. For example, in the case where new parameters such as the shortest wavelength λS and the longest wavelength λL are received from the exposure control processor 210, it is determined that the various parameters are changed.

[0243] In the case where the various parameters are changed (S158: Yes), the laser control processor 130 ends the process of the present flowchart, and returns to the process shown in Figure 11 .

[0244] In the case where the various parameters are not changed (S158: No), the laser control processor 130 returns to S142 of Figure 15 . The processes of S142 to S158 of Figure 16 are repeated, whereby the first mode and the second mode are alternately performed.

[0245] 2.6 Specific example of wavelength change

[0246] Figure 17Ais a graph showing the wavelength change set in the case where the number of irradiation pulses N is odd in the first embodiment. In Figure 17A In Fig. 1, the horizontal axis represents the pulse number n, and the vertical axis represents the wavelength λ.

[0247] The first mode of the wavelength change includes 16 pulses from the first (n = 1) to the 16th (n = 16). The first mode starts from the shortest wavelength λS, and the wavelength is changed by the wavelength change amount δλl at a time every 1 pulse, and finally becomes the longest wavelength λL.

[0248] The second mode of the wavelength change includes 15 pulses from the 17th (n = 17) to the 31st (n = 31). The second mode starts from a value obtained by subtracting half of δλl from the longest wavelength λL, and the wavelength is changed by the wavelength change amount -δλl at a time every 1 pulse, and finally becomes a value obtained by adding half of δλl to the shortest wavelength λS.

[0249] By thus setting the first mode and the second mode, the wavelength change mode becomes a mode with a period of 31 pulses, and therefore, the moving average value every 31 pulses is constant regardless of how the consecutive 31 pulses are selected.

[0250] Figure 17B is a graph showing the change of the wavelength change amount in the case where the number of irradiation pulses N is odd in the first embodiment. In Figure 17B In Fig. 1, the horizontal axis represents the pulse number n, and the vertical axis represents the wavelength change amount δλ.

[0251] In the 15 pulses from the second (n = 2) to the 16th (n = 16), the wavelength change amount δλ is constant at δλl. That is, the wavelength λ is increased by δλl at a time every 1 pulse from the previous pulse.

[0252] In the 17th (n = 17) pulse, the wavelength change amount δλ is -δλl / 2.

[0253] In the 14 pulses from the 18th (n = 18) to the 31st (n = 31), the wavelength change amount δλ is constant at -δλl. That is, the wavelength λ is changed by -δλl at a time every 1 pulse from the previous pulse, and the value of the wavelength λ is decreased.

[0254] In the 32nd (n = 32) pulse, the wavelength change amount δλ is -δλl / 2.

[0255] In the first embodiment, in the case where the number of irradiation pulses N is odd, the wavelength λ is repeatedly increased and decreased as described above.

[0256] Figure 17C is a graph showing the cumulative spectrum of 31 pulses in the wavelength change shown in Fig. 1. In Figure 17A Fig. 2 is a graph showing the cumulative spectrum of 31 pulses in the wavelength change shown in Fig. 1. InFigure 17C In the diagram, the horizontal axis represents wavelength λ, and the vertical axis represents light intensity. Figure 17A In the wavelength variations shown, the pulses included in mode 1 and mode 2 are offset by δλ¹ / ², therefore, in Figure 17C The cumulative spectrum shown does not exhibit any obvious steep wavelength peaks. By keeping the light intensity of the 31 pulses approximately constant, the cumulative spectrum can be made to have a roughly flat-topped shape.

[0257] 2.7 Function

[0258] According to the first embodiment, the narrowband gas laser device 100 includes a rotating stage 422 for varying the center wavelength λ of a pulsed laser, and a laser control processor 130 for controlling the rotating stage 422. The laser control processor 130 reads parameters including the number of irradiation pulses N, the shortest wavelength λS, and the longest wavelength λL of the pulsed laser irradiating a portion of an irradiated object (S100). Furthermore, the laser control processor 130 sets the first mode and the second mode in a manner that at least one of the first mode and the second mode differs when the number of irradiation pulses N is even and when the number of irradiation pulses N is odd. The first mode is a mode in which the center wavelength λ varies from the shortest wavelength λS to the longest wavelength λL, and the second mode is a mode in which the center wavelength λ varies from the longest wavelength λL to the shortest wavelength λS (S110). The laser control processor 130 alternates between the first mode and the second mode. Figure 12 , Figure 13 , Figure 15 , Figure 16 The rotary table 422 is controlled in a manner that allows for different wavelength variations δλ1 depending on whether the number of irradiation pulses N is even or odd (S121, S141). Alternatively, the target wavelength λt of the second mode may also differ depending on whether the number of irradiation pulses N is even or odd (S133, S153).

[0259] Therefore, appropriate wavelength variation modes can be set for both even-numbered and odd-numbered illumination pulses N. Since the moving average of the illumination pulse number N remains constant regardless of the selected consecutive N pulses, differences in the average wavelength due to the illumination position in the scanning field SF are prevented, reducing deviations in exposure results caused by the illumination position.

[0260] According to the first embodiment, in a case where the number N of irradiation pulses is odd, the laser control processor 130 sets either of the first mode and the second mode in such a manner that the wavelength variation amount -δλ1 / 2 between the first pulse (n = 17 or n = 32) and the previous pulse and the wavelength variation amount -δλ1 or δλ1 between the other pulses and the respective previous pulses are different in either of the first mode and the second mode. Figure 17A , Figure 17B ).

[0261] Thus, in a case where the number N of irradiation pulses is odd, even if the number of pulses of the first mode and the number of pulses of the second mode are different, it is possible to arrange the plurality of pulses approximately equally in the wavelength region between the shortest wavelength λS and the longest wavelength λL, and it is possible to make the cumulative spectrum approximately flat.

[0262] According to the first embodiment, in a case where the number N of irradiation pulses is odd, the wavelength variation amount -δλ1 / 2 between the first pulse (n = 17, n = 32) and the previous pulse and the wavelength variation amount -δλ1 or δλ1 between the other pulses and the respective previous pulses are different in either of the first mode and the second mode. Figure 17A , Figure 17B ).

[0263] Thus, in a case where the number N of irradiation pulses is odd, by staggering the wavelength variation amount of the first pulse in either of the first mode and the second mode, it is possible to make the cumulative spectrum approximately flat.

[0264] According to the first embodiment, in a case where the number N of irradiation pulses is odd, the number of pulses (N + 1) / 2 in the first mode is made larger than the number of pulses (N - 1) / 2 in the second mode (S146, S156). Moreover, the wavelength variation amount -δλ1 / 2 between the first pulse (n = 32) and the previous pulse in the first mode and the wavelength variation amount -δλ1 / 2 between the first pulse (n = 17) and the previous pulse in the second mode are half the wavelength variation amount -δλ1 between the other pulses and the respective previous pulses in the second mode. Figure 17A , Figure 17B ).

[0265] Thus, in a case where the number N of irradiation pulses is odd, the wavelength variation amount of the first pulse in the first mode and the second mode is staggered by half, and it is possible to make the cumulative spectrum approximately flat.

[0266] According to the first embodiment, when the number of irradiation pulses N is odd, the laser control processor 130 sets the number of pulses in the first mode of the irradiation pulse number N to (N+1) / 2 (S146). Furthermore, the wavelength change δλ1 between the second and subsequent pulses in the first mode and the previous pulse is set to (λL-λS) / ((N-1) / 2) (S141). The wavelength change between the initial pulse (n=32) in the first mode and the previous pulse is set to -δλ1 / 2 ( Figure 17A , Figure 17B The wavelength change between the second and subsequent pulses in mode 2 and the previous pulse is set to -δλ1. Figure 17A , Figure 17B The wavelength change between the initial pulse (n=17) and the previous pulse in mode 2 is set to -δλ1 / 2. Figure 17A , Figure 17B ).

[0267] Therefore, when the number of irradiation pulses N is odd, by specifying the wavelength changes of the first mode and the second mode, the cumulative spectrum can be made to have an approximately flat-top shape.

[0268] According to the first embodiment, when the number of irradiation pulses N is even, the laser control processor 130 sets the number of pulses in the first mode of the irradiation pulse number N to N / 2 (S126). Furthermore, the wavelength change between the first pulse (n=31) in the first mode and the previous pulse is set to 0 ( Figure 14A , Figure 14B In mode 1, the wavelength change δλ1 between the second and subsequent pulses and the previous pulse is set to (λL-λS) / (N / 2-1)(S121). In mode 2, the wavelength change between the initial pulse (n=16) and the previous pulse is set to 0. Figure 14A , Figure 14B The wavelength change between the second and subsequent pulses in mode 2 and the previous pulse is set to -δλ1. Figure 14A , Figure 14B ).

[0269] Therefore, by varying the wavelength in multiple stages between the shortest wavelength λS and the longest wavelength λL, multiple wavelength peaks appear in the cumulative spectrum. If the light intensity of each pulse is kept approximately constant, these wavelength peaks become approximately the same light intensity, making the cumulative spectrum approximately flat-topped.

[0270] In other respects, the first embodiment is the same as the comparative example.

[0271] 3. Variations when the number of irradiation pulses N is even.

[0272] 3.1 Actions

[0273] Figure 18 and Figure 19 This is a flowchart showing the processing sequence of wavelength control when the number of irradiation pulses N is an even number in the second embodiment. Figure 18 and Figure 19 The process shown is equivalent to Figure 11 The sub-step of S120 is a variation of the case where the number of irradiation pulses N is even in the first embodiment.

[0274] In the second embodiment, the first mode is performed in the first 15 pulses out of 30 pulses, and the second mode is performed in the last 15 pulses, which is the same as in the first embodiment.

[0275] First, in S121a, the laser control processor 130 calculates the wavelength change δλ1 using the following formula.

[0276] δλ1=(λL-λS) / (N / 2)

[0277] When the number of irradiation pulses N is 30 (N=30), the wavelength change δλ1 is the value obtained by dividing the difference between the longest wavelength λL and the shortest wavelength λS by 15.

[0278] In the following processes S122 to S127, the wavelength of mode 1 is changed.

[0279] The processing of S122 to S127 is respectively with Figure 12 The processing of S122 to S127 is the same.

[0280] exist Figure 19 In the processing of S132 to S137, the wavelength of the second mode is changed.

[0281] The processing of S132~S137 and S138 is respectively with Figure 13 The processing of S132 to S137 and S138 is the same.

[0282] 3.2 Specific examples of wavelength variation

[0283] Figure 20A This is a graph showing the wavelength variation set in the second embodiment when the number of irradiation pulses N is an even number. Figure 20A In the diagram, the horizontal axis represents the pulse number n, and the vertical axis represents the wavelength λ.

[0284] The first pattern of wavelength variation includes 15 pulses from the first (n=l) to the 15th (n=l5). The first pattern starts from the shortest wavelength λs, and the wavelength is changed by the wavelength variation amount δλl every 1 pulse. However, the wavelength variation amount (λL-λS) / (N / 2) in the second embodiment is slightly smaller than the wavelength variation amount (λL-λS) / (N / 2-l) in the first embodiment, and thus the 15th (n=l5) pulse does not reach the longest wavelength λL.

[0285] The second pattern of wavelength variation includes 15 pulses from the 16th (n=l6) to the 30th (n=30). The second pattern starts from the longest wavelength λL, and the wavelength is changed by the wavelength variation amount -δλl every 1 pulse. However, the 30th (n=30) pulse does not reach the shortest wavelength λS.

[0286] By thus setting the first pattern and the second pattern, the wavelength variation pattern becomes a pattern with a period of 30 pulses, and thus the moving average every 30 pulses is constant regardless of how the 30 consecutive pulses are selected.

[0287] The wavelength difference between the wavelength of the last 15th (n=l5) pulse of the first pattern and the wavelength of the first 16th (n=l6) pulse of the second pattern, i.e., the longest wavelength λL, is δλl. That is, the wavelength variation amount of the first 16th (n=l6) pulse of the second pattern is δλl.

[0288] The wavelength difference between the wavelength of the last 30th (n=30) pulse of the second pattern and the wavelength of the first 31st (n=31) pulse of the first pattern, i.e., the shortest wavelength λS, is -δλl. That is, the wavelength variation amount of the first 31st (n=31) pulse of the first pattern is -δλl.

[0289] Figure 20B Fig. 16 is a graph showing the progress of the wavelength variation amount in the case where the number N of pulses to be irradiated is even in the second embodiment. In Fig. 16, the horizontal axis represents the pulse number n, and the vertical axis represents the wavelength variation amount δλ. Figure 20B

[0290] In the 15 pulses from the second (n=2) to the 16th (n=l6), the wavelength variation amount δλ is constant, and is δλl. That is, the wavelength λ is increased by δλl every time from the previous pulse.

[0291] In the 15 pulses from the 17th (n=l7) to the 31st (n=31), the wavelength variation amount δλ is constant, and is -δλl. That is, the wavelength λ is changed by -δλl every time from the previous pulse, and the value of the wavelength λ is decreased.

[0292] ​In the second embodiment, in the case where the number N of irradiation pulses is even, the wavelength λ is repeatedly increased and decreased as described above.

[0293] Figure 20C is a graph showing the cumulative spectrum of 30 pulses in the wavelength variation shown in Figure 20A In Figure 20C , the horizontal axis represents the wavelength λ, and the vertical axis represents the light intensity. In Figure 20A , the wavelength is multistage- varied between the shortest wavelength λS and the longest wavelength λL, and thus, in the cumulative spectrum shown in Figure 20C , a plurality of wavelength peaks appear between the shortest wavelength λS and the longest wavelength λL. If the light intensity of 30 pulses is maintained substantially constant, the plurality of wavelength peaks shown in Figure 20C become substantially the same light intensity as each other, and it is possible to make the cumulative spectrum substantially flat. However, only one pulse is generated in each of the longest wavelength λL and the shortest wavelength λS, and thus, the light intensity in the longest wavelength λL and the shortest wavelength λS becomes a light intensity of about half the intensity of the other wavelength peaks.

[0294] 3.3 Effects

[0295] According to the second embodiment, in the case where the number N of irradiation pulses is even, the laser control processor 130 sets the number of pulses in the first pattern in the number N of irradiation pulses to N / 2 (S126). Further, the wavelength variation amount δλ1 between each pulse in the first pattern and the previous pulse is set to (λL-λS) / (N / 2) (S121a). The wavelength variation amount between each pulse in the second pattern and the previous pulse is set to -δλ1 (S121b). Figure 20A Figure 20B ).

[0296] Thus, since the wavelength is multistage-varied between the shortest wavelength λS and the longest wavelength λL, a plurality of wavelength peaks appear in the cumulative spectrum, and as long as the light intensity of each pulse is maintained substantially constant, these wavelength peaks become substantially the same light intensity as each other, and it is possible to make the cumulative spectrum substantially flat.

[0297] As for other aspects, the second embodiment is the same as the first embodiment.

[0298] 4. Modified example of the case where the number N of irradiation pulses is odd

[0299] 4.1 Action

[0300] Figure 21 and Figure 22 is a flowchart showing the processing order of the wavelength control in the case where the number N of irradiation pulses is odd in the third embodiment. Figure 21 and Figure 22 the processing shown in​Figure 11 The subroutine of S140 is a variation of the case where the number of irradiation pulses N is odd in the first embodiment.

[0301] In the third embodiment, the first mode is performed in the first 16 pulses out of 31 pulses, and the second mode is performed in the last 15 pulses, which is the same as in the first embodiment.

[0302] First, in S141a, the laser control processor 130 calculates the wavelength changes δλ1 and δλ2 using the following formulas.

[0303] δλ1=(λL-λS) / ((N-1) / 2)

[0304] δλ2=-(λL-λS) / ((N+1) / 2)

[0305] The wavelength change δλ1 is the wavelength change used in mode 1. When the number of irradiation pulses N is 31 (N=31), the wavelength change δλ1 is the value obtained by dividing the difference between the longest wavelength λL and the shortest wavelength λS by 15.

[0306] The wavelength change δλ2 is the wavelength change used in mode 2. When the number of irradiation pulses N is 31 (N=31), the wavelength change δλ2 is the value obtained by multiplying the difference between the longest wavelength λL and the shortest wavelength λS by 16 by -1.

[0307] In the following processing steps S142 to S147, the wavelength of mode 1 is changed.

[0308] The processing of S142 to S147 is respectively with Figure 15 The processing of S142 to S147 is the same.

[0309] exist Figure 22 In the processing of S152 to S157, the wavelength of the second mode is changed.

[0310] In S152, the laser control processor 130 sets the counter i, which is used to count the number of pulses, back to 1.

[0311] Next, in S153a, the laser control processor 130 calculates the target wavelength λt using the following formula.

[0312] λt=λL+i·δλ2

[0313] When the value of counter i is 1 (i=1), the target wavelength λt becomes the value obtained by adding δλ2 to the longest wavelength λL.

[0314] The target wavelength λt is decreased by the wavelength variation amount δλ2 each time as the value of the counter i increases one by one.

[0315] The processes of S154 to S158 next are the same as those of S154 to S158 of Figure 16 the first embodiment.

[0316] 4.2 Specific example of wavelength variation

[0317] Figure 23A is a graph showing the wavelength variation set in the case where the number N of irradiation pulses is odd in the third embodiment. In Figure 23A , the horizontal axis represents the pulse number n, and the vertical axis represents the wavelength λ.

[0318] The first mode of wavelength variation includes 16 pulses from the first (n = 1) to the 16th (n = 16). The first mode starts from the shortest wavelength λs, and the wavelength is varied by the wavelength variation amount δλl each time by 1 pulse, and finally becomes the longest wavelength λL.

[0319] The second mode of wavelength variation includes 15 pulses from the 17th (n = 17) to the 31st (n = 31). The second mode starts from the value obtained by adding δλ2 to the longest wavelength λL, and the wavelength is varied by the wavelength variation amount δλ2 each time by 1 pulse, and finally becomes a value larger than the shortest wavelength λs by -δλ2.

[0320] By thus setting the first mode and the second mode, the wavelength variation mode becomes a mode with a period of 31 pulses, and therefore, the moving average value per 31 pulses is constant regardless of how the 31 consecutive pulses are selected.

[0321] The wavelength difference between the wavelength of the last 16th (n = 16) pulse of the first mode, which is the longest wavelength λL, and the wavelength of the first 17th (n = 17) pulse of the second mode is δλ2. That is, the wavelength variation amount of the first 17th (n = 17) pulse of the second mode is δλ2. The wavelength variation amount δλ2 has an absolute value slightly smaller than that of the wavelength variation amount δλl.

[0322] The wavelength difference between the wavelength of the last 31st (n = 31) pulse of the second mode and the wavelength of the first 32nd (n = 32) pulse of the first mode, which is the shortest wavelength λs, is δλ2. That is, the wavelength variation amount of the first pulse of the first mode is δλ2.

[0323] Figure 23B is a graph showing the passage of the wavelength variation amount in the case where the number N of irradiation pulses is odd in the third embodiment. In Figure 23B , the horizontal axis represents the pulse number n, and the vertical axis represents the wavelength variation amount δλ.

[0324] In 15 pulses from the 2nd (n = 2) to the 16th (n = 16), the wavelength variation δλ is constant, and is δλ1. That is, the wavelength λ is increased by δλ1 each time from the previous pulse.

[0325] In 16 pulses from the 17th (n = 17) to the 32nd (n = 32), the wavelength variation δλ is constant, and is δλ2. That is, the wavelength λ is decreased by δλ2 each time from the previous pulse.

[0326] In the 3rd embodiment, in the case where the number of irradiation pulses N is odd, the wavelength λ is repeatedly increased and decreased as described above.

[0327] Figure 23C is a graph showing the cumulative spectrum of 31 pulses in the wavelength variation shown in Figure 23A is a graph showing the cumulative spectrum of 31 pulses in the wavelength variation shown in Figure 23C In Figure 23A is a graph showing the cumulative spectrum of 31 pulses in the wavelength variation shown in Figure 23C In the cumulative spectrum shown in Figure 23C The multiple wavelength peaks shown in

[0328] 4.3 Effects

[0329] According to the 3rd embodiment, in the case where the number of irradiation pulses N is odd, the laser control processor 130 sets the 1st mode and the 2nd mode in such a manner that the absolute value of the wavelength variation δλ1 between each pulse in the 1st mode and the previous pulse is different from the absolute value of the wavelength variation δλ2 between each pulse in the 2nd mode and the previous pulse (S141a).

[0330] Thus, in the case where the number of irradiation pulses N is odd, even if the number of pulses in the 1st mode and the number of pulses in the 2nd mode are different, it is possible to arrange multiple pulses approximately equally in the wavelength region between the shortest wavelength λS and the longest wavelength λL, and it is possible to make the cumulative spectrum approximately flat.

[0331] According to the third embodiment, in the case where the number N of irradiation pulses is odd, the ratio of the absolute value of the wavelength variation amount δλ1 between each pulse and the previous pulse in the first mode to the absolute value of the wavelength variation amount δλ2 between each pulse and the previous pulse in the second mode is equal to the ratio of the number of pulses in the second mode (N-1) / 2 to the number of pulses in the first mode (N+1) / 2 in the number N of irradiation pulses (S141a, S146, S156).

[0332] Thus, in the case where the number N of irradiation pulses is odd, the number of pulses in the first mode and the number of pulses in the second mode can be set so that the cumulative spectrum becomes a substantially flat shape.

[0333] According to the third embodiment, in the case where the number N of irradiation pulses is odd, the laser control processor 130 sets the number of pulses in the first mode in the number N of irradiation pulses to (N+1) / 2 (S146). Further, the wavelength variation amount δλ1 between each pulse and the previous pulse in the first mode is set to (λL-λS) / ((N-1) / 2), and the wavelength variation amount δλ2 between each pulse and the previous pulse in the second mode is set to -(λL-λS) / ((N+1) / 2) (S141a).

[0334] Thus, in the case where the number N of irradiation pulses is odd, even if the number of pulses in the first mode and the number of pulses in the second mode are different, the cumulative spectrum can be made to become a substantially flat shape.

[0335] As for other aspects, the third embodiment is the same as the first embodiment.

[0336] Alternatively, the second embodiment can be applied in the case where the number N of irradiation pulses is even, and the third embodiment can be applied in the case where the number N of irradiation pulses is odd, in a combined manner.

[0337] 5. Other

[0338] The above description is not restrictive, but is a simple example. Therefore, it is understood by those skilled in the art that modifications can be made to the embodiments of the present application without departing from the scope of the claims. Further, it is understood by those skilled in the art that the embodiments of the present application can be used in combination.

[0339] The terms used in the specification and the claims should be interpreted as "non- limiting" terms if not specifically stated otherwise. For example, the terms such as "comprise" or "comprising" should be interpreted as "not limited to the recited parts". The term such as "have" should be interpreted as "not limited to the recited parts". In addition, the indefinite article "a" should be interpreted as "at least one" or "one or more". Furthermore, the term 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". And, it should be interpreted as further including a combination of parts other than "A", "B", and "C".

Claims

1. A narrowband gas laser device, comprising: An actuator that changes the center wavelength of a pulsed laser; and A processor controls the actuator by reading parameters including the number of irradiation pulses, the shortest wavelength, and the longest wavelength of a pulsed laser irradiating a portion of an irradiated object. The processor sets the first and second modes in a manner different from at least one of the following: when the number of irradiation pulses is even and when the number of irradiation pulses is odd. The processor controls the actuator by alternating between the first and second modes. The first mode is a mode in which the center wavelength varies from the shortest wavelength to the longest wavelength, and the second mode is a mode in which the center wavelength varies from the longest wavelength to the shortest wavelength. When the number of irradiation pulses is odd, the processor sets any of the first and second modes in such a way that the wavelength change between one pulse and the previous pulse is different from the wavelength change between each of the other multiple pulses and the previous pulse.

2. The narrowband gas laser device according to claim 1, wherein, In either the first mode or the second mode, the wavelength change between the initial pulse and the previous pulse is different from the wavelength change between each of the other pulses and the previous pulse.

3. The narrowband gas laser device according to claim 1, wherein, The number of pulses in the first mode of the irradiation pulse count is greater than the number of pulses in the second mode of the irradiation pulse count. The wavelength change between the initial pulse and the preceding pulse in the first mode and the wavelength change between the initial pulse and the preceding pulse in the second mode are half the wavelength changes between each of the other pulses and the preceding pulse in the second mode.

4. The narrowband gas laser device according to claim 1, wherein, When the processor sets the shortest wavelength to λS and the longest wavelength to λL, Set the number of pulses in the first mode of the irradiation pulse number N to (N+1) / 2. Let the wavelength change δλ1 between the second and subsequent pulses in the first mode and the previous pulse be (λL-λS) / ((N-1) / 2). The wavelength change between the initial pulse and the previous pulse in the first mode is set to -δλ1 / 2. The wavelength change between the second and subsequent pulses in the second mode and the previous pulse is set to -δλ1. The wavelength change between the initial pulse and the previous pulse in the second mode is set to -δλ1 / 2.

5. The narrowband gas laser device according to claim 1, wherein, When the number of irradiation pulses is odd, the processor sets the first mode and the second mode in such a way that the absolute value of the wavelength change between each pulse in the first mode and the previous pulse is different from the absolute value of the wavelength change between each pulse in the second mode and the previous pulse.

6. The narrowband gas laser device according to claim 5, wherein, The ratio of the absolute value of the wavelength change between each pulse in the first mode and the previous pulse to the absolute value of the wavelength change between each pulse in the second mode and the previous pulse is equal to the ratio of the number of pulses in the second mode to the number of pulses in the first mode in the total number of irradiation pulses.

7. The narrowband gas laser device according to claim 5, wherein, When the processor sets the shortest wavelength to λS and the longest wavelength to λL, Set the number of pulses in the first mode of the irradiation pulse number N to (N+1) / 2. The wavelength change between each pulse in the first mode and the previous pulse is set as (λL-λS) / ((N-1) / 2). The wavelength change between each pulse in the second mode and the previous pulse is set as -(λL-λS) / ((N+1) / 2).

8. The narrowband gas laser device according to claim 1, wherein, When the processor sets the shortest wavelength to λS and the longest wavelength to λL, and the number of irradiation pulses is even, Set the number of pulses in the first mode of the irradiation pulse number N to N / 2. Set the wavelength change between the initial pulse and the previous pulse in the first mode to 0. Let the wavelength change δλ1 between the second and subsequent pulses in the first mode and the previous pulse be (λL-λS) / (N / 2-1). The wavelength change between the initial pulse and the previous pulse in the second mode is set to 0. The wavelength change between the second and subsequent pulses in the second mode and the previous pulse is set to -δλ1.

9. The narrowband gas laser device according to claim 1, wherein, When the processor sets the shortest wavelength to λS and the longest wavelength to λL, and the number of irradiation pulses is even, Set the number of pulses in the first mode of the irradiation pulse number N to N / 2. The wavelength change δλ1 between each pulse in the first mode and the previous pulse is set as (λL-λS) / (N / 2). The wavelength change between each pulse in the second mode and the previous pulse is set to -δλ1.

10. A wavelength control method for controlling the center wavelength of a pulsed laser output from a narrowband gas laser device, wherein, The wavelength control method includes the following steps: The system reads in parameters including the number of irradiation pulses, the shortest wavelength, and the longest wavelength of the pulsed laser applied to one part of the irradiated object; and... The first mode and the second mode are set in a manner that differs from at least one of the following: when the number of irradiation pulses is even and when the number of irradiation pulses is odd. The actuator that changes the center wavelength is controlled by alternating between the first mode and the second mode, wherein the first mode changes the center wavelength in a manner that approaches the longest wavelength, and the second mode changes the center wavelength in a manner that approaches the shortest wavelength. When the number of irradiation pulses is odd, the first mode and the second mode are set in such a way that in either the first mode or the second mode, the wavelength change between one pulse and the previous pulse is different from the wavelength change between each of the other multiple pulses and the previous pulse.

11. The wavelength control method according to claim 10, wherein, In either the first mode or the second mode, the wavelength change between the initial pulse and the previous pulse is different from the wavelength change between each of the other pulses and the previous pulse.

12. The wavelength control method according to claim 10, wherein, The number of pulses in the first mode of the irradiation pulse count is greater than the number of pulses in the second mode of the irradiation pulse count. The wavelength change between the initial pulse and the preceding pulse in the first mode and the wavelength change between the initial pulse and the preceding pulse in the second mode are half the wavelength changes between each of the other pulses and the preceding pulse in the second mode.

13. The wavelength control method according to claim 10, wherein, When the shortest wavelength is set to λS and the longest wavelength is set to λL, Set the number of pulses in the first mode of the irradiation pulse number N to (N+1) / 2. Let the wavelength change δλ1 between the second and subsequent pulses in the first mode and the previous pulse be (λL-λS) / ((N-1) / 2). The wavelength change between the initial pulse and the previous pulse in the first mode is set to -δλ1 / 2. The wavelength change between the second and subsequent pulses in the second mode and the previous pulse is set to -δλ1. The wavelength change between the initial pulse and the previous pulse in the second mode is set to -δλ1 / 2.

14. The wavelength control method according to claim 10, wherein, When the number of irradiation pulses is odd, the first mode and the second mode are set in such a way that the absolute value of the wavelength change between each pulse in the first mode and the previous pulse is different from the absolute value of the wavelength change between each pulse in the second mode and the previous pulse.

15. The wavelength control method according to claim 14, wherein, The ratio of the absolute value of the wavelength change between each pulse in the first mode and the previous pulse to the absolute value of the wavelength change between each pulse in the second mode and the previous pulse is equal to the ratio of the number of pulses in the second mode to the number of pulses in the first mode in the total number of irradiation pulses.

16. The wavelength control method according to claim 14, wherein, When the shortest wavelength is set to λS and the longest wavelength is set to λL, Set the number of pulses in the first mode of the irradiation pulse number N to (N+1) / 2. The wavelength change between each pulse in the first mode and the previous pulse is set as (λL-λS) / ((N-1) / 2). The wavelength change between each pulse in the second mode and the previous pulse is set as -(λL-λS) / ((N+1) / 2).

17. The wavelength control method according to claim 10, wherein, When the shortest wavelength is set to λS and the longest wavelength is set to λL, and the number of irradiation pulses is even, Set the number of pulses in the first mode of the irradiation pulse number N to N / 2. Set the wavelength change between the initial pulse and the previous pulse in the first mode to 0. Let the wavelength change δλ1 between the second and subsequent pulses in the first mode and the previous pulse be (λL-λS) / (N / 2-1). The wavelength change between the initial pulse and the previous pulse in the second mode is set to 0. The wavelength change between the second and subsequent pulses in the second mode and the previous pulse is set to -δλ1.

18. A method for manufacturing an electronic device, comprising the following steps: Pulsed lasers are generated using a narrowband gas laser device. The pulsed laser is output to the exposure device. The pulsed laser is used to expose a photosensitive substrate within the exposure apparatus to manufacture electronic devices. The narrowband gas laser device has the following features: An actuator that changes the center wavelength of a pulsed laser; and A processor controls the actuator by reading parameters including the number of irradiation pulses, the shortest wavelength, and the longest wavelength of the pulsed laser irradiating a portion of the irradiated object. The processor sets the first mode and the second mode in a manner different from at least one of the following: when the number of irradiation pulses is even and when the number of irradiation pulses is odd. The processor controls the actuator by alternating between the first mode and the second mode. The first mode is a mode in which the center wavelength varies from the shortest wavelength to the longest wavelength, and the second mode is a mode in which the center wavelength varies from the longest wavelength to the shortest wavelength. When the number of irradiation pulses is odd, the processor sets any of the first and second modes in such a way that the wavelength change between one pulse and the previous pulse is different from the wavelength change between each of the other multiple pulses and the previous pulse.

Images