Laser device, spectral linewidth measurement method, and electronic device manufacturing method

Abstract

This laser device comprises a wavelength adjustor, and is provided with: a laser oscillator which outputs pulse laser light having a central wavelength that is adjusted by the wavelength adjustor; a spectrum monitor which generates spectrum data of the pulse laser light; and a processor which controls the wavelength adjustor so that the central wavelength of the pulse laser light varies according to a target wavelength that periodically varies to become a plurality of values including a first wavelength and a second wavelength, calculates a first spectral linewidth from spectral data of a plurality of pulses in which the first wavelength is the target wavelength, and calculates a second spectral linewidth from spectral data of a plurality of pulses in which the second wavelength is the target wavelength.

Description

[Technical Field]

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

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

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

[0004] [Patent Document 1] Summary of the specification of U.S. Patent Application Publication No. 2005 / 083983

[0005] A laser apparatus according to one aspect of the present disclosure includes: a laser oscillator including a wavelength tuning device that outputs pulsed laser light having a center wavelength tuned by the wavelength tuning device; a spectrum monitor that generates spectral data of the pulsed laser light; and a processor that controls the wavelength tuning device so that the center wavelength of the pulsed laser light varies in accordance with a target wavelength that periodically varies to a plurality of values ​​including a first wavelength and a second wavelength, calculates a first spectral linewidth from the spectral data of a plurality of pulses having the first wavelength as the target wavelength, and calculates a second spectral linewidth from the spectral data of a plurality of pulses having the second wavelength as the target wavelength.

[0006] A method for measuring a spectral linewidth according to one aspect of the present disclosure includes changing a center wavelength of a pulsed laser beam in accordance with a target wavelength that periodically changes to a plurality of values ​​including a first wavelength and a second wavelength, calculating a first spectral linewidth from spectral data of a plurality of pulses having the first wavelength as the target wavelength, and calculating a second spectral linewidth from spectral data of a plurality of pulses having the second wavelength as the target wavelength.

[0007] A method for manufacturing an electronic device according to one aspect of the present disclosure includes generating pulsed laser light using a laser apparatus including: a laser oscillator including a wavelength adjuster, outputting pulsed laser light having a center wavelength adjusted by the wavelength adjuster; a spectrum monitor generating spectral data of the pulsed laser light; and a processor controlling the wavelength adjuster so that the center wavelength of the pulsed laser light varies in accordance with a target wavelength that periodically varies to a plurality of values ​​including a first wavelength and a second wavelength; calculating a first spectral linewidth from the spectral data of a plurality of pulses having the first wavelength as the target wavelength; and calculating a second spectral linewidth from the spectral data of a plurality of pulses having the second wavelength as the target wavelength; outputting the pulsed laser light to an exposure apparatus; and exposing the pulsed laser light onto a photosensitive substrate in the exposure apparatus to manufacture an electronic device. [Brief explanation of the drawings]

[0008] Some embodiments of the present disclosure will now be described, by way of example only, with reference to the accompanying drawings, in which: [Figure 1] FIG. 1 shows a schematic configuration of an exposure system in a comparative example. [Figure 2] FIG. 2 shows a schematic configuration of a laser device according to a comparative example. [Figure 3] FIG. 3 is a time chart showing a method for measuring the spectral linewidth in a comparative example. [Figure 4] FIG. 4 is a flowchart showing a method for measuring the spectral linewidth in a comparative example. [Figure 5] FIG. 5 shows an example of a spectral waveform for explaining E95. [Figure 6] FIG. 6 is a graph showing an example in which the target wavelength of the pulsed laser beam is changed periodically. [Figure 7] FIG. 7 shows the spectral waveform of the pulsed laser light for each pulse when the target wavelength is changed periodically. [Figure 8] FIG. 8 shows a schematic configuration of the laser device according to the first embodiment. [Figure 9] FIG. 9 is a time chart showing the method for measuring the spectral linewidth in the first embodiment. [Figure 10] FIG. 10 is a flowchart showing a method for measuring a spectral linewidth in the first embodiment. [Figure 11] FIG. 11 is a time chart showing a method for measuring a spectral linewidth in the second embodiment. [Figure 12] FIG. 12 is a time chart showing a method for measuring a spectral linewidth in the third embodiment. Embodiment

[0009] <Contents> 1. Comparative Example 1.1 Configuration of exposure apparatus 100 1.2 Operation of the exposure apparatus 100 1.3 Configuration of laser device 1 1.3.1 Laser oscillator 20 1.3.2 Monitor Module 16 1.3.3 Various processing equipment 1.4 Operation 1.4.1 Laser Control Processor 30 1.4.2 Laser oscillator 20 1.4.3 Monitor Module 16 1.4.4 Wavelength measurement control processor 50 1.4.5 Spectral Measurement Control Processor 60 1.5 Issues in the comparative example 2. Implementation in which fringe waveforms of multiple pulses are integrated for each target wavelength 2.1 Configuration 2.2 Operation 2.3 Effect 3. An embodiment using the fringe waveform of a pulse other than the first pulse of a burst 3.1 Operation 3.2 Effect 4. An embodiment using a continuous pulse fringe waveform 4.1 Operation 4.2 Effect 5.Other

[0010] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. The embodiments described below show some examples of the present disclosure and do not limit the content of the present disclosure. Furthermore, not all of the configurations and operations described in each embodiment are necessarily essential as the configurations and operations of the present disclosure. Note that the same components are given the same reference symbols, and redundant explanations will be omitted.

[0011] 1. Comparative Example 1 shows a schematic configuration of an exposure system in a comparative example. The comparative example in the present disclosure is a configuration that the applicant recognizes as being known only by the applicant, and is not a publicly known example that the applicant acknowledges.

[0012] The exposure system includes a laser apparatus 1 and an exposure apparatus 100. The exposure apparatus 100 is an example of an external apparatus in the present disclosure. The laser apparatus 1 includes a laser control processor 30. The laser control processor 30 is a processing device including a memory 32 in which a control program is stored and a CPU (central processing unit) 31 that executes the control program. The laser control processor 30 is specially configured or programmed to execute various processes included in the present disclosure. The laser control processor 30 constitutes the processor in the present disclosure. The laser apparatus 1 is configured to output pulsed laser light toward the exposure apparatus 100.

[0013] 1.1 Configuration of exposure apparatus 100 The exposure apparatus 100 includes an illumination optical system 101 , a projection optical system 102 , and an exposure control processor 110 . The illumination optical system 101 illuminates a reticle pattern of a reticle (not shown) arranged on a reticle stage RT with pulsed laser light incident from the laser device 1. The projection optical system 102 reduces and projects the pulsed laser light that has passed through the reticle, forming an image on a workpiece (not shown) placed on a workpiece table WT. The workpiece is a photosensitive substrate such as a semiconductor wafer coated with a resist film.

[0014] The exposure control processor 110 is a processing device that includes a memory 112 that stores a control program, and a CPU 111 that executes the control program. The exposure control processor 110 is specially configured or programmed to execute various processes included in the present disclosure. The exposure control processor 110 manages the overall control of the exposure apparatus 100, and transmits and receives various data and signals to and from the laser control processor 30.

[0015] 1.2 Operation of the exposure apparatus 100 The exposure control processor 110 transmits setting data for the target wavelength, the target spectral linewidth, and the target pulse energy, as well as trigger signals, to the laser control processor 30. The laser control processor 30 controls the laser device 1 in accordance with these data and signals. The exposure control processor 110 synchronizes the reticle stage RT and the workpiece table WT and translates them in opposite directions, thereby exposing the workpiece to a pulsed laser beam that reflects the reticle pattern. The reticle pattern is transferred onto the semiconductor wafer through this exposure process, after which electronic devices can be manufactured through multiple processes.

[0016] 1.3 Configuration of laser device 1 2 shows a schematic configuration of a laser apparatus 1 according to a comparative example. The laser apparatus 1 includes a laser oscillator 20, a monitor module 16, a laser control processor 30, a wavelength measurement control processor 50, and a spectrum measurement control processor 60. The laser apparatus 1 is connectable to an exposure apparatus 100. The wavelength measurement control processor 50 and the spectrum measurement control processor 60 constitute the processors of the present disclosure.

[0017] 1.3.1 Laser oscillator 20 The laser oscillator 20 includes a laser chamber 10, a discharge electrode 11a, a power supply 12, a line narrowing module 14, and a spectrum adjuster 15a.

[0018] The line-narrowing module 14 and the spectrum adjuster 15a constitute a laser resonator. The laser chamber 10 is disposed in the optical path of the laser resonator. Windows 10a and 10b are provided at both ends of the laser chamber 10. A discharge electrode 11a and a paired discharge electrode (not shown) are disposed inside the laser chamber 10. The discharge electrode (not shown) is positioned so as to overlap with the discharge electrode 11a in the direction of the V-axis perpendicular to the paper surface. The laser chamber 10 is filled with a laser gas containing, for example, argon gas or krypton gas as a rare gas, fluorine gas as a halogen gas, and neon gas as a buffer gas. The power supply 12 includes a switch 13 and is connected to the discharge electrode 11a and a charger (not shown).

[0019] The line narrowing module 14 includes a plurality of prisms 14a and 14b and a grating 14c. The prisms 14a and 14b are arranged in this order in the optical path of the light emitted from the window 10a. The surfaces of the prisms 14a and 14b where the light enters and exits are both parallel to the V-axis. The prism 14b is supported by a rotation stage 14e. The rotation stage 14e is connected to a wavelength driver 51. The rotation stage 14e corresponds to the wavelength tuner in this disclosure. The grating 14c is disposed in the optical path of the light transmitted through the prisms 14a and 14b. The direction of the grooves of the grating 14c is parallel to the V axis.

[0020] The spectral adjuster 15a includes a cylindrical plano-convex lens 15b and a cylindrical plano-concave lens 15c. The cylindrical plano-concave lens 15c is located between the laser chamber 10 and the cylindrical plano-convex lens 15b. The cylindrical plano-concave lens 15c is supported by a linear stage 15d. The linear stage 15d is connected to a spectral driver 64.

[0021] The cylindrical plano-convex lens 15b and the cylindrical plano-concave lens 15c are arranged so that the convex surface of the cylindrical plano-convex lens 15b faces the concave surface of the cylindrical plano-concave lens 15c. The convex surface of the cylindrical plano-convex lens 15b and the concave surface of the cylindrical plano-concave lens 15c each have a focal axis parallel to the V-axis. The flat surface opposite the convex surface of the cylindrical plano-convex lens 15b is coated with a partially reflective film.

[0022] 1.3.2 Monitor Module 16 The monitor module 16 is disposed in the optical path of the pulsed laser beam between the spectral adjuster 15a and the exposure apparatus 100. The monitor module 16 includes beam splitters 16a, 16b, and 17a, an energy sensor 16c, a high-reflection mirror 17b, a wavelength monitor 18, and a spectral monitor 19.

[0023] Beam splitter 16a is located in the optical path of the pulsed laser beam output from spectrum adjuster 15a. Beam splitter 16a is configured to transmit a portion of the pulsed laser beam toward exposure apparatus 100 with high transmittance and reflect the other portion. Beam splitter 16b is located in the optical path of the pulsed laser beam reflected by beam splitter 16a. Energy sensor 16c is located in the optical path of the pulsed laser beam reflected by beam splitter 16b.

[0024] Beam splitter 17a is located in the optical path of the pulsed laser beam that has passed through beam splitter 16b. High-reflection mirror 17b is located in the optical path of the pulsed laser beam that has been reflected by beam splitter 17a.

[0025] Wavelength monitor 18 is disposed in the optical path of the pulsed laser light transmitted through beam splitter 17a and includes a diffusion plate 18a, an etalon 18b, a condenser lens 18c, and a line sensor 18d.

[0026] The diffusion plate 18a is located in the optical path of the pulsed laser light that has passed through the beam splitter 17a. The diffusion plate 18a has many projections and recesses on its surface, and is configured to transmit and diffuse the pulsed laser light. The etalon 18b is located in the optical path of the pulsed laser light transmitted through the diffusion plate 18a. The etalon 18b includes two partially reflecting mirrors. The two partially reflecting mirrors face each other with a predetermined air gap between them and are bonded together via a spacer.

[0027] The condenser lens 18c is located in the optical path of the pulsed laser light that has passed through the etalon 18b. Line sensor 18d is located on the optical path of the pulsed laser light that has passed through condenser lens 18c, at the focal plane of condenser lens 18c. Line sensor 18d is a light distribution sensor including a large number of light-receiving elements arranged one-dimensionally. Alternatively, a photodiode array or an image sensor including a large number of light-receiving elements arranged two-dimensionally may be used instead of line sensor 18d.

[0028] The line sensor 18d receives interference fringes formed by the etalon 18b and the condenser lens 18c. The interference fringes are an interference pattern of pulsed laser light and have a concentric circular shape, and the square of the distance from the center of the concentric circle is proportional to the change in wavelength.

[0029] The spectrum monitor 19 is disposed in the optical path of the pulsed laser beam reflected by the high-reflection mirror 17b. The spectrum monitor 19 includes a diffusion plate 19a, an etalon 19b, a condenser lens 19c, and a line sensor 19d. These components are similar to the diffusion plate 18a, etalon 18b, condenser lens 18c, and line sensor 18d included in the wavelength monitor 18, respectively. However, the etalon 19b has a smaller free spectral range than the etalon 18b. The condenser lens 19c has a longer focal length than the condenser lens 18c.

[0030] 1.3.3 Various processing equipment The spectrum measurement control processor 60 is a processing device including a memory 62 in which a control program is stored, a CPU 61 that executes the control program, and a counter 63. The spectrum measurement control processor 60 is specially configured or programmed to execute various processes included in the present disclosure.

[0031] The memory 62 also stores various data for calculating the spectral linewidth. The various data include an instrumental function of the spectrum monitor 19. The counter 63 counts the number of pulses of the pulsed laser beam by counting the number of times an electrical signal including pulse energy data output from the energy sensor 16c is received. Alternatively, the counter 63 may count the number of pulses of the pulsed laser beam by counting oscillation trigger signals output from the laser control processor 30.

[0032] The wavelength measurement control processor 50 is a processing device including a memory (not shown) in which a control program is stored, a CPU (not shown) that executes the control program, and a counter (not shown). The wavelength measurement control processor 50 is specially configured or programmed to execute various processes included in the present disclosure. The counter included in the wavelength measurement control processor 50 counts the number of pulses of the pulsed laser light, similar to the counter 63.

[0033] In this disclosure, the laser control processor 30, the wavelength measurement control processor 50, and the spectrum measurement control processor 60 are described as separate components, but the laser control processor 30 may also serve as both the wavelength measurement control processor 50 and the spectrum measurement control processor 60.

[0034] 1.4 Operation 1.4.1 Laser Control Processor 30 The laser control processor 30 transmits setting data for the voltage to be applied to the discharge electrode 11a to the power supply 12 based on setting data for the target pulse energy received from the exposure control processor 110. The laser control processor 30 transmits setting data for the target wavelength and target spectral linewidth received from the exposure control processor 110 to the wavelength measurement control processor 50 and the spectrum measurement control processor 60, respectively. In addition, the laser control processor 30 transmits an oscillation trigger signal based on the trigger signal received from the exposure control processor 110 to the switch 13 included in the power supply 12.

[0035] 1.4.2 Laser oscillator 20 The switch 13 is turned on when it receives an oscillation trigger signal from the laser control processor 30. When the switch 13 is turned on, the power supply 12 generates a pulsed high voltage from the electrical energy stored in a charger (not shown) and applies this high voltage to the discharge electrode 11a.

[0036] When a high voltage is applied to the discharge electrode 11a, a discharge occurs inside the laser chamber 10. The energy of this discharge excites the laser medium inside the laser chamber 10, causing it to transition to a higher energy level. When the excited laser medium then transitions to a lower energy level, it emits light with a wavelength corresponding to the difference in energy levels.

[0037] Light generated inside the laser chamber 10 is emitted to the outside of the laser chamber 10 through windows 10a and 10b. The beam width of the light emitted from the window 10a of the laser chamber 10 is expanded by prisms 14a and 14b, and then enters the grating 14c. Light incident on the grating 14c from the prisms 14a and 14b is reflected by the multiple grooves of the grating 14c and diffracted in a direction according to the wavelength of the light.

[0038] Prisms 14a and 14b reduce the beam width of the diffracted light from grating 14c and return the light to laser chamber 10 through window 10a. The spectral adjuster 15a transmits and outputs a portion of the light emitted from the window 10b of the laser chamber 10, and reflects the other portion back into the laser chamber 10 via the window 10b.

[0039] In this way, the light emitted from the laser chamber 10 travels back and forth between the line-narrowing module 14 and the spectrum adjuster 15a, and is amplified each time it passes through the discharge space inside the laser chamber 10. This light is narrowed in line each time it is reflected by the line-narrowing module 14. The light thus oscillated in the laser oscillator 20 and narrowed in line is output as pulsed laser light from the spectrum adjuster 15a.

[0040] The rotary stage 14e included in the line narrowing module 14 rotates the prism 14b around an axis parallel to the V axis in accordance with a drive signal output from the wavelength driver 51. By rotating the prism 14b, the selected wavelength of the line narrowing module 14 is adjusted, and the central wavelength of the pulsed laser light is adjusted.

[0041] The linear stage 15d included in the spectral tuning unit 15a moves the cylindrical plano-concave lens 15c along the optical path between the laser chamber 10 and the cylindrical plano-convex lens 15b in accordance with a drive signal output from the spectral driver 64. This changes the wavefront of the light traveling from the spectral tuning unit 15a to the line narrowing module 14. The change in the wavefront adjusts the spectral waveform and spectral linewidth of the pulsed laser light.

[0042] 1.4.3 Monitor Module 16 The energy sensor 16c detects the pulse energy of the pulsed laser light and outputs pulse energy data to the laser control processor 30, the wavelength measurement control processor 50, and the spectrum measurement control processor 60. The pulse energy data is used by the laser control processor 30 to feedback control the setting data of the voltage applied to the discharge electrode 11a. In addition, the electrical signal containing the pulse energy data can be used by the wavelength measurement control processor 50 and the spectrum measurement control processor 60 to count the number of pulses of the pulsed laser light.

[0043] In wavelength monitor 18, a waveform of interference fringes is generated from the amount of light at each of the light-receiving elements included in line sensor 18d that receive the interference fringes. The waveform of interference fringes is also called a fringe waveform. Line sensor 18d may generate a fringe waveform by integrating the amount of light at each of the light-receiving elements over multiple pulses included in the pulsed laser beam by performing exposure for a fixed period of time.

[0044] In the spectrum monitor 19, a fringe waveform is generated from the amount of light at each of the light receiving elements included in the line sensor 19d that received the interference fringes. The line sensor 19d may generate a fringe waveform by integrating the amount of light at each of the light receiving elements over multiple pulses included in the pulsed laser beam by performing exposure for a fixed period of time.

[0045] 1.4.4 Wavelength measurement control processor 50 The wavelength measurement control processor 50 counts the number of pulses of the pulsed laser light and sends a data output trigger to the wavelength monitor 18 every time a certain number of pulses is accumulated. The wavelength measurement control processor 50 receives a fringe waveform output from the wavelength monitor 18 in accordance with the data output trigger. Using this fringe waveform, the wavelength measurement control processor 50 calculates the central wavelength of the pulsed laser light. The wavelength measurement control processor 50 performs feedback control of the center wavelength of the pulsed laser light by outputting a wavelength control signal to the wavelength driver 51 based on the calculated center wavelength and the target wavelength received from the laser control processor 30.

[0046] 1.4.5 Spectral Measurement Control Processor 60 3 is a time chart showing a method for measuring the spectral linewidth in a comparative example. Individual pulses of pulsed laser light are generated in response to an oscillation trigger signal, and line sensor 19d in spectrum monitor 19 is exposed to light, thereby generating a fringe waveform by integrating the light amounts of multiple pulses. The spectrum measurement control processor 60 counts the number of pulses of the pulsed laser light, and outputs a data output trigger to the spectrum monitor 19 for each accumulated number of pulses n. The accumulated number of pulses n is, for example, 4.

[0047] Fig. 4 is a flowchart showing a method for measuring a spectral linewidth in a comparative example. The process shown in Fig. 4 is executed each time a pulsed laser beam with a cumulative pulse number n is output. In S1, the spectrum measurement control processor 60 receives a fringe waveform obtained by integrating the light amounts of four pulses from the spectrum monitor 19. For example, it receives a fringe waveform i1 obtained by integrating the light amounts of pulses #1 to #4 shown in FIG.

[0048] In S3, the spectrum measurement control processor 60 performs the following process to convert the fringe waveform into a spectral waveform. First, a portion of the fringe waveform corresponding to the free spectral range is extracted. The portion of the waveform extracted from the fringe waveform indicates the relationship between the distance from the center of the concentric circles that make up the interference fringes and the light intensity. Next, the spectrum measurement control processor 60 performs coordinate conversion of this waveform into a relationship between wavelength and light intensity. Converting a portion of the fringe waveform into a relationship between wavelength and light intensity is called mapping to wavelength space. Through this coordinate conversion, the spectrum measurement control processor 60 obtains a spectral waveform. Both the fringe waveform data and the spectral waveform data are examples of spectral data in this disclosure.

[0049] Although the case where the spectrum measurement control processor 60 converts the fringe waveform into a spectral waveform has been described here, the present disclosure is not limited to this case, and the spectrum monitor 19 may also convert the fringe waveform into a spectral waveform.

[0050] In S4, the spectrum measurement control processor 60 calculates the spectral linewidth based on the spectral waveform. For example, the spectral linewidth w1 is calculated based on the spectral waveform obtained from the fringe waveform i1 shown in FIG.

[0051] Calculating the spectral linewidth may include estimating the true spectral waveform incident on the spectrum monitor 19 by deconvolving the spectral waveform with the instrumental function of the spectrum monitor 19, and then calculating the spectral linewidth from the estimated true spectral waveform. The deconvolution may require a calculation time longer than the repetition period of the pulsed laser beam. In Figure 3, an example of the time required to calculate the spectral linewidths w1, w5, etc. is shown by the horizontal length of the pentagonal frame. During one calculation of the spectral linewidth, multiple pulses of pulsed laser beam are newly output.

[0052] The spectral line width may be the full width at half maximum or an index called E95. Figure 5 shows an example of a spectral waveform to explain E95. The horizontal axis of Figure 5 represents wavelength, and the vertical axis represents light intensity. E95 is the full width of the portion of the total energy of this spectrum that occupies 95% of the total energy, centered around the central wavelength λ0.

[0053] The spectral measurement control processor 60 sends the spectral linewidth to the laser control processor 30 . 4, the laser control processor 30 transmits the spectral linewidth to the exposure apparatus 100. After S5, the processing of this flowchart ends. Pulse #5 and subsequent pulses shown in FIG. 3 are similar to pulses #1 to #4.

[0054] 1.5 Issues in the comparative example FIG. 6 is a graph showing an example in which the target wavelength of the pulsed laser beam is changed periodically. The laser oscillator 20 performs laser oscillation at a repetition rate above a certain level for a certain period of time in response to a trigger signal from the exposure control processor 110. Performing laser oscillation at a repetition rate above a certain level and outputting pulsed laser light is called "burst oscillation."

[0055] When the trigger signal from the exposure control processor 110 stops, the laser oscillator 20 stops burst oscillation. After that, the laser oscillator 20 starts burst oscillation again in response to the trigger signal from the exposure control processor 110. The period between the first burst oscillation and the subsequent second burst oscillation is called the "stop period."

[0056] The period during which burst oscillation is performed corresponds, for example, to the period during which exposure of one exposure area of ​​a semiconductor wafer is performed in exposure apparatus 100. The idle period corresponds, for example, to the period during which the imaging position of the reticle pattern is moved from one exposure area to another exposure area in exposure apparatus 100, or the period during which the semiconductor wafer is replaced. Adjustment oscillation may be performed during the idle period to adjust various parameters.

[0057] The target wavelength is periodically changed to a plurality of values ​​including the first wavelength λa and the second wavelength λb, and the rotary stage 14e is controlled in accordance with the target wavelength, thereby periodically changing the central wavelength of the pulsed laser beam. The focal length in the exposure apparatus 100 depends on the wavelength of the pulsed laser beam. The periodic change in the central wavelength periodically changes the imaging position in the direction of the optical path axis of the pulsed laser beam, thereby effectively increasing the depth of focus. For example, even when exposing a thick resist film, imaging performance in the thickness direction of the resist film can be maintained. Alternatively, the resist profile, which indicates the cross-sectional shape of the developed resist film, can be adjusted.

[0058] However, if the target wavelength is changed periodically, the spectral linewidth may not be measured properly. This will be explained with reference to FIG.

[0059] Fig. 7 shows the spectral waveform of pulsed laser light for each pulse when the target wavelength is changed periodically. Fig. 7 shows the case where pulses P1 to P8 are output in ascending order of their numbers while the target wavelength is switched between the first wavelength λa and the second wavelength λb, one pulse at a time. Pulses P1, P3, P5, and P7 have the first wavelength λa as their target wavelength, and pulses P2, P4, P6, and P8 have the second wavelength λb as their target wavelength.

[0060] The average spectral waveform shown at the bottom of FIG. 7 is obtained by dividing the optical intensity of the integrated spectral waveform obtained by integrating the spectral waveforms of pulses P1 to P8 by the number of pulses, 8. When spectral waveforms are averaged, the spectral waveforms of the individual pulses may have a shape that is significantly different from their average spectral waveform. The average spectral waveform may include peaks near the first wavelength λa and the second wavelength λb, or may have a substantially flat-top shape between the first wavelength λa and the second wavelength λb. Such an average spectral waveform may be useful, for example, for evaluating the wavelength distribution of multiple pulses irradiated onto a single location on a semiconductor wafer. However, an average spectral waveform that is significantly different from the spectral waveforms of the individual pulses may not be useful, for example, for appropriately controlling the spectral adjuster 15a.

[0061] 2. Implementation in which fringe waveforms of multiple pulses are integrated for each target wavelength 2.1 Configuration 8 shows a schematic configuration of a laser device 1a according to the first embodiment. The laser device 1a according to the first embodiment differs from the laser device 1 according to the comparative example in the following respects. The memory 62 of the spectrum measurement control processor 60 includes first and second buffers Bu1 and Bu2. The wavelength measurement control processor 50 also transmits the wavelength control signal to the wavelength driver 51 to the spectrum measurement control processor 60 .

[0062] The first and second buffers Bu1 and Bu2 are memory areas that temporarily store integrated fringe waveforms obtained by integrating fringe waveforms. The spectrum measurement control processor 60 determines whether the fringe waveform received from the spectrum monitor 19 is a fringe waveform of a pulse having the first wavelength λa or the second wavelength λb as the target wavelength. This determination can be made based on a wavelength control signal that indicates the control content of the rotation stage 14e by the wavelength measurement control processor 50. The CPU 61 included in the spectrum measurement control processor 60, or a selector (not shown) connected thereto, integrates and stores the fringe waveform in either the first or second buffer Bu1 or Bu2 according to the determination result. The number of buffers is not limited to two; more buffers may be provided depending on the number of target wavelengths.

[0063] 2.2 Operation FIG. 9 is a time chart showing the method for measuring the spectral linewidth in the first embodiment. The wavelength measurement control processor 50 controls the rotation stage 14e by outputting a wavelength control signal in accordance with the target wavelength that periodically changes between a first wavelength λa and a second wavelength λb. The central wavelength of the pulsed laser light changes in response to the change in the target wavelength. Pulses with the first wavelength λa as the target wavelength are designated a1, a2, . . . , and pulses with the second wavelength λb as the target wavelength are designated b1, b2, . . . Here, a case will be described in which the target wavelength switches between the first wavelength λa and the second wavelength λb one pulse at a time, but the switching of the target wavelength is not limited to one pulse at a time.

[0064] The spectrum measurement control processor 60 outputs a data output trigger for each pulse of the pulsed laser light. The spectrum monitor 19 outputs fringe waveforms fa1, fb1, fa2, fb2, ... for each pulse in accordance with the data output trigger.

[0065] FIG. 10 is a flowchart showing a method for measuring a spectral linewidth in the first embodiment. In S1a, spectrum measurement control processor 60 receives fringe waveforms fa1, fb1, fa2, fb2, and so on for each pulse from spectrum monitor 19. As shown in Fig. 9, fringe waveforms fa1, fb1, fa2, fb2, and so on include fringe waveforms fa1, fa2, and so on of pulses a1, a2, and so on whose target wavelength is the first wavelength λa, and fringe waveforms fb1, fb2, and so on of pulses b1, b2, and so on whose target wavelength is the second wavelength λb. The period from when spectrum measurement control processor 60 receives fringe waveform fa1 of pulse a1 to when it receives fringe waveform fa4 of pulse a4 partially overlaps with the period from when spectrum measurement control processor 60 receives fringe waveform fb1 of pulse b1 to when it receives fringe waveform fb4 of pulse b4.

[0066] The spectrum measurement control processor 60 accumulates fringe waveforms as they are received sequentially, updating the accumulated fringe waveform. Each time the spectrum measurement control processor 60 updates the accumulated fringe waveform, it overwrites and stores the updated waveform in a different buffer depending on the target wavelength. The accumulated fringe waveform ia1 is obtained by accumulating fringe waveforms fa1, fa2, ... of multiple pulses a1, a2, ... whose target wavelength is a first wavelength λa, and the accumulated fringe waveform ib1 is obtained by accumulating fringe waveforms fb1, fb2, ... of multiple pulses b1, b2, ... whose target wavelength is a second wavelength λb. The accumulated fringe waveform ia1 is stored in a first buffer Bu1, and the accumulated fringe waveform ib1 is stored in a second buffer Bu2. The accumulated fringe waveform ia1 corresponds to the first accumulated fringe waveform in this disclosure, and the accumulated fringe waveform ib1 corresponds to the second accumulated fringe waveform in this disclosure. The data for the integrated fringe waveform ia1 is an example of first integrated spectral data in the present disclosure, and the data for the integrated fringe waveform ib1 is an example of second integrated spectral data in the present disclosure. If the number of integrated pulses n is 4, the fringe waveforms fa1 to fa4 are integrated, and once the fringe waveforms fb1 to fb4 have been integrated, the process proceeds to S2a.

[0067] In S2a, the spectrum measurement control processor 60 calculates an average fringe waveform by dividing the light intensity of each of the integrated fringe waveforms ia1 and ib1 by the number of integrated pulses n. The average fringe waveform is calculated for each target wavelength. The average fringe waveform obtained from the integrated fringe waveform ia1 corresponds to the first average fringe waveform in this disclosure, and this data is an example of first average spectral data. The average fringe waveform obtained from the integrated fringe waveform ib1 corresponds to the second average fringe waveform in this disclosure, and this data is an example of second average spectral data. The integrated fringe waveform data and the average fringe waveform data are both examples of spectral data in this disclosure.

[0068] In S3a, the spectrum measurement control processor 60 extracts a portion of the average fringe waveform that corresponds to the free spectral range and converts this waveform into a spectral waveform. The conversion to a spectral waveform is performed for each target wavelength. The spectral waveform obtained by converting the average fringe waveform obtained from the integrated fringe waveform ia1 corresponds to the first spectral waveform in this disclosure, and the spectral waveform obtained by converting the average fringe waveform obtained from the integrated fringe waveform ib1 corresponds to the second spectral waveform in this disclosure.

[0069] In S4a, the spectrum measurement control processor 60 calculates the spectral linewidth based on the spectral waveform. The spectral linewidth is calculated for each target wavelength. For example, as shown in FIG. 9, the spectral linewidth wa1 is calculated based on the spectral waveform obtained from the integrated fringe waveform ia1, and the spectral linewidth wb1 is calculated based on the spectral waveform obtained from the integrated fringe waveform ib1. The spectral linewidth wa1 corresponds to the first spectral linewidth in this disclosure, and the spectral linewidth wb1 corresponds to the second spectral linewidth in this disclosure.

[0070] The spectral measurement control processor 60 sends the spectral linewidth to the laser control processor 30 . In S5a of Figure 10, the laser control processor 30 transmits the spectral linewidth to the exposure apparatus 100. Transmission to the exposure apparatus 100 is performed without distinguishing between target wavelengths. The laser control processor 30 may also transmit the spectral linewidth to a lithography control processor (not shown). The lithography control processor may be a processor that oversees the control of multiple exposure apparatuses. After S5a, the processing of this flowchart ends. Pulse a5 and subsequent pulses shown in FIG. 9 are similar to pulses a1 to a4, and pulse b5 and subsequent pulses are similar to pulses b1 to b4.

[0071] Here, we have described calculating the spectral linewidth based on the fringe waveform received from spectrum monitor 19, but this fringe waveform can also be used to calculate the center wavelength. For example, a first center wavelength can be calculated from the fringe waveform of a pulse whose target wavelength is a first wavelength λa, and a second center wavelength can be calculated from the fringe waveform of a pulse whose target wavelength is a second wavelength λb. Etalon 19b included in spectrum monitor 19 has a smaller free spectral range than etalon 18b included in wavelength monitor 18, so the center wavelength can be measured with high resolution by using the fringe waveform received from spectrum monitor 19.

[0072] 2.3 Effect (1) According to the first embodiment, the laser apparatus 1a includes a laser oscillator 20, a spectrum monitor 19, a wavelength measurement control processor 50, and a spectrum measurement control processor 60. The laser oscillator 20 includes a rotation stage 14e and outputs pulsed laser light having a center wavelength adjusted by the rotation stage 14e. The spectrum monitor 19 acquires fringe waveforms fa1, fb1, fa2, fb2, ... of the pulsed laser light. The wavelength measurement control processor 50 controls the rotation stage 14e so that the center wavelength of the pulsed laser light changes in accordance with a target wavelength that periodically changes to a plurality of values ​​including a first wavelength λa and a second wavelength λb. The spectrum measurement control processor 60 calculates a spectral linewidth wa1 from the fringe waveforms fa1, fa2, ... of multiple pulses a1, a2, ... with the first wavelength λa as the target wavelength, and calculates a spectral linewidth wb1 from the fringe waveforms fb1, fb2, ... of multiple pulses b1, b2, ... with the second wavelength λb as the target wavelength. This allows the spectral linewidths wa1 and wb1 to be calculated appropriately for each target wavelength.

[0073] (2) According to the first embodiment, the spectrum measurement control processor 60 determines whether the fringe waveform received from the spectrum monitor 19 is a fringe waveform of a pulse having the first wavelength λa or the second wavelength λb as the target wavelength, based on information indicating the control content of the rotation stage 14e by the wavelength measurement control processor 50. This makes it possible to accurately determine whether the fringe waveform is of a pulse having the first wavelength λa or the second wavelength λb as the target wavelength, and to calculate the spectral linewidths wa1 and wb1 for each target wavelength.

[0074] (3) According to the first embodiment, the spectrum measurement control processor 60 includes first and second buffers Bu1 and Bu2. The spectrum measurement control processor 60 stores an integrated fringe waveform ia1 of pulses a1, a2, ..., with a first wavelength λa as the target wavelength in the first buffer Bu1, and stores an integrated fringe waveform ib1 of pulses b1, b2, ..., with a second wavelength λb as the target wavelength in the second buffer Bu2. According to this, by using a plurality of buffers Bu1 and Bu2, the calculation of the spectral linewidths wa1 and wb1 for each target wavelength can be made more efficient.

[0075] (4) According to the first embodiment, the spectrum measurement control processor 60 accumulates and updates the accumulated fringe waveform ia1 each time it receives fringe waveforms fa1, fa2, ... of pulses a1, a2, ... whose target wavelength is the first wavelength λa, and overwrites and stores the accumulated fringe waveform ia1 in the first buffer Bu1 each time it receives fringe waveforms fb1, fb2, ... of pulses b1, b2, ... whose target wavelength is the second wavelength λb, and overwrites and stores the accumulated fringe waveform ib1 in the second buffer Bu2 each time it receives fringe waveforms fb1, fb2, ... of pulses b1, b2, ... whose target wavelength is the second wavelength λb. According to this, each time a fringe waveform is received, it is accumulated to update the accumulated fringe waveforms ia1 and ib1, and then overwritten and stored, so there is no need to store the fringe waveform for each pulse, and the required storage area can be reduced.

[0076] (5) According to the first embodiment, the spectrum measurement control processor 60 accumulates the fringe waveforms fa1 to fa4 of pulses a1 to a4 having the first wavelength λa as the target wavelength each time the spectrum measurement control processor 60 receives them, updates the accumulated fringe waveform ia1, and stores the accumulated fringe waveform ia1 in the first buffer Bu1 each time the spectrum measurement control processor 60 receives them, updates the accumulated fringe waveform ib1, and stores the accumulated fringe waveform ib1 in the second buffer Bu2 each time the spectrum measurement control processor 60 receives them. Here, the period from when the spectrum measurement control processor 60 receives the fringe waveform fa1 of pulse a1 to when it receives the fringe waveform fa4 of pulse a4 partially overlaps with the period from when the spectrum measurement control processor 60 receives the fringe waveform fb1 of pulse b1 to when it receives the fringe waveform fb4 of pulse b4. This allows the integrated fringe waveform ia1 stored in the first buffer Bu1 and the integrated fringe waveform ib1 stored in the second buffer Bu2 to be updated while the other is maintained, thereby enabling efficient updating of the integrated fringe waveforms ia1 and ib1 for each target wavelength.

[0077] (6) According to the first embodiment, the spectrum measurement control processor 60 calculates first integrated spectral data by integrating fringe waveforms fa1, fa2, ... of multiple pulses a1, a2, ... having a first wavelength λa as a target wavelength, and calculates a spectral linewidth wa1 from the first integrated spectral data. The spectrum measurement control processor 60 calculates second integrated spectral data by integrating fringe waveforms fb1, fb2, ... of multiple pulses b1, b2, ... having a second wavelength λb as a target wavelength, and calculates a spectral linewidth wb1 from the second integrated spectral data. When the spectrum monitor 19 converts the fringe waveforms into spectral waveforms, the spectrum measurement control processor 60 may calculate the first and second integrated spectral data by integrating the spectral waveforms for each target wavelength. According to this, the fringe waveform or the spectral waveform is integrated for each target wavelength, so that the spectral linewidths wa1 and wb1 can be calculated appropriately for each target wavelength.

[0078] (7) According to the first embodiment, the spectrum measurement control processor 60 calculates first average spectrum data by averaging fringe waveforms fa1, fa2, ... of multiple pulses a1, a2, ... having a first wavelength λa as a target wavelength, and calculates a spectral linewidth wa1 from the first average spectrum data. The spectrum measurement control processor 60 calculates second average spectrum data by averaging fringe waveforms fb1, fb2, ... of multiple pulses b1, b2, ... having a second wavelength λb as a target wavelength, and calculates a spectral linewidth wb1 from the second average spectrum data. If the spectrum monitor 19 converts the fringe waveforms into spectral waveforms, the spectrum measurement control processor 60 may calculate the first and second average spectrum data by averaging the spectral waveforms for each target wavelength. According to this, the fringe waveform or spectral waveform is averaged for each target wavelength, so that the spectral linewidths wa1 and wb1 can be calculated appropriately for each target wavelength.

[0079] (8) According to the first embodiment, the spectrum measurement control processor 60 receives fringe waveforms fa1, fb1, fa2, fb2, ... for each pulse from the spectrum monitor 19. The spectrum measurement control processor 60 integrates the fringe waveforms fa1, fa2, ... of multiple pulses a1, a2, ... having a first wavelength λa as a target wavelength to calculate an integrated fringe waveform ia1, calculates a first spectral waveform from the integrated fringe waveform ia1, and calculates a spectral linewidth wa1 from the first spectral waveform. The spectrum measurement control processor 60 integrates the fringe waveforms fb1, fb2, ... of multiple pulses b1, b2, ... having a second wavelength λb as a target wavelength to calculate an integrated fringe waveform ib1, calculates a second spectral waveform from the integrated fringe waveform ib1, and calculates a spectral linewidth wb1 from the second spectral waveform. According to this, since the fringe waveform is integrated for each target wavelength, the spectral linewidths wa1 and wb1 can be calculated appropriately for each target wavelength.

[0080] (9) According to the first embodiment, the spectrum measurement control processor 60 calculates a first average fringe waveform by averaging fringe waveforms fa1, fa2, ... of multiple pulses a1, a2, ... having a first wavelength λa as a target wavelength, calculates a first spectral waveform from the first average fringe waveform, and calculates a spectral linewidth wa1 from the first spectral waveform.The spectrum measurement control processor 60 calculates a second average fringe waveform by averaging fringe waveforms fb1, fb2, ... of multiple pulses b1, b2, ... having a second wavelength λb as a target wavelength, calculates a second spectral waveform from the second average fringe waveform, and calculates a spectral linewidth wb1 from the second spectral waveform. According to this, the fringe waveforms are averaged for each target wavelength, so that the spectral linewidths wa1 and wb1 can be calculated appropriately for each target wavelength.

[0081] (10) According to the first embodiment, the laser control processor 30 included in the laser apparatus 1a transmits the spectral linewidth wa1 for the first wavelength λa and the spectral linewidth wb1 for the second wavelength λb to the exposure apparatus 100 without distinguishing between them. This eliminates the need to transmit information for distinguishing the target wavelength, thereby reducing the load on the communication device.

[0082] (11) According to the first embodiment, the spectrum measurement control processor 60 calculates a first center wavelength from fringe waveforms fa1, fa2, ... of multiple pulses a1, a2, ... having a first wavelength λa as a target wavelength, and calculates a second center wavelength from fringe waveforms fb1, fb2, ... of multiple pulses b1, b2, ... having a second wavelength λb as a target wavelength. This allows the fringe waveforms fa1, fb1, fa2, fb2, ... generated by spectrum monitor 19 to be used to calculate the center wavelength. The center wavelength calculated in this manner can also be used to calibrate wavelength monitor 18. In other respects, the first embodiment is similar to the comparative example.

[0083] 3. An embodiment using the fringe waveform of a pulse other than the first pulse of a burst 3.1 Operation 11 is a time chart showing a method for measuring a spectral linewidth in the second embodiment. The configuration of the laser apparatus 1a according to the second embodiment is different from that of the first embodiment in that the memory 62 of the spectrum measurement control processor 60 includes a buffer (not shown) for discarding data, but is otherwise similar to that of the first embodiment.

[0084] The wavelength measurement control processor 50 generates a wavelength control signal to switch the target wavelength between the first wavelength λa and the second wavelength λb every three pulses, but the switching of the target wavelength is not limited to every three pulses.

[0085] 9, the spectrum measurement control processor 60 outputs a data output trigger for each pulse of the pulsed laser light. The spectrum monitor 19 outputs fringe waveforms fa1, fa2, ... and fb1, fb2, ... for each pulse in accordance with the data output trigger.

[0086] 10, the spectrum measurement control processor 60 receives fringe waveforms fa1, fa2, . . . and fb1, fb2, . . . for each pulse from the spectrum monitor 19.

[0087] The spectrum measurement control processor 60 stores fringe waveforms fa1, fa2, and fa3 of the first pulses a1, a2, and a3 of the burst of pulsed laser light output by burst oscillation in a data discard buffer (not shown). The number of pulses stored in the data discard buffer is three, but is not limited to this.

[0088] The data of the fringe waveforms fa1, fa2, and fa3 are temporarily stored in a buffer and then discarded. Alternatively, the data may be discarded without being temporarily stored in a buffer. Alternatively, the data may be stored separately as log data in a non-volatile memory (not shown).

[0089] The spectrum measurement control processor 60 integrates the fringe waveforms fb1, fb2, fb3, and fb4 of the pulses b1, b2, b3, and b4, and stores the integrated fringe waveform ib1 in the second buffer Bu2.

[0090] The spectrum measurement control processor 60 integrates the fringe waveforms fa4, fa5, fa6, and fa7 of the pulses a4, a5, a6, and a7, and stores the integrated fringe waveform ia4 in the first buffer Bu1.

[0091] 10, the spectrum measurement control processor 60 calculates the spectral linewidth based on the spectral waveform, except that the fringe waveforms fa1, fa2, and fa3 of the first pulses a1, a2, and a3 of the burst are excluded from the calculation of the spectral linewidth. The spectral linewidth is calculated for each target wavelength. For example, as shown in Figure 11, the spectral linewidth wb1 is calculated based on the spectral waveform obtained from the integrated fringe waveform ib1, and the spectral linewidth wa4 is calculated based on the spectral waveform obtained from the integrated fringe waveform ia4. Pulse b5 and onwards are similar to pulses b1 to b4, and pulse a8 and onwards are similar to pulses a4 to a7.

[0092] 3.2 Effect (12) According to the second embodiment, the laser oscillator 20 is configured to output pulsed laser light by performing multiple burst oscillations, including a first burst oscillation and a second burst oscillation that follows the first burst oscillation. The spectrum measurement control processor 60 calculates the spectral linewidths wb1 and wa4 by excluding the fringe waveforms fa1 to fa3 of the first pulses a1 to a3 of each burst. According to this, the fringe waveforms fa1 to fa3 of the pulses a1 to a3 that are not used as exposure light in the exposure tool 100 are excluded, so the load of calculating the spectral linewidth can be reduced.

[0093] (13) According to the second embodiment, the spectrum measurement control processor 60 discards the excluded fringe waveforms fa1 to fa3. According to this, by discarding the fringe waveforms fa1 to fa3, the required storage area can be reduced.

[0094] (14) According to the second embodiment, the spectrum measurement control processor 60 stores the excluded fringe waveforms fa1 to fa3 separately. According to this, by storing the fringe waveforms fa1 to fa3 that were not used in calculating the spectral linewidth, they can be used for data analysis in the event of a malfunction. In other respects, the second embodiment is similar to the first embodiment.

[0095] 4. An embodiment using a continuous pulse fringe waveform 4.1 Operation 12 is a time chart showing a method for measuring the spectral linewidth in the third embodiment. The configuration of the laser device 1a according to the third embodiment is the same as that of the second embodiment.

[0096] The wavelength measurement control processor 50 generates a wavelength control signal to switch the target wavelength between the first wavelength λa and the second wavelength λb by five pulses at a time. That is, one cycle of wavelength change includes successively outputting a first number of pulses of the first wavelength λa and successively outputting a second number of pulses of the second wavelength λb, where the first number and the second number are, for example, 5. In this way, the target wavelength is switched by a number of pulses greater than the cumulative number of pulses n, for example, 4 pulses.

[0097] 9, the spectrum measurement control processor 60 outputs a data output trigger for each pulse of the pulsed laser light. The spectrum monitor 19 outputs fringe waveforms fa1, fa2, ... and fb1, fb2, ... for each pulse in accordance with the data output trigger.

[0098] 10, the spectrum measurement control processor 60 receives fringe waveforms fa1, fa2, . . . and fb1, fb2, . . . for each pulse from the spectrum monitor 19.

[0099] The spectrum measurement control processor 60 accumulates the fringe waveforms fa1, fa2, fa3, and fa4 of pulses a1, a2, a3, and a4 as they are received in sequence, and updates the accumulated fringe waveform ia1. Each time the spectrum measurement control processor 60 updates the accumulated fringe waveform ia1, it overwrites and stores it in the first buffer Bu1.

[0100] The spectrum measurement control processor 60 accumulates the fringe waveforms fb1, fb2, fb3, and fb4 of pulses b1, b2, b3, and b4 as they are received in sequence, and updates the accumulated fringe waveform ib1. Each time the spectrum measurement control processor 60 updates the accumulated fringe waveform ib1, it overwrites and stores it in the second buffer Bu2.

[0101] The spectrum measurement control processor 60 stores the fringe waveforms fa5 and fb5 of the remaining pulses a5 and b5, excluding the four pulses corresponding to the cumulative pulse number n out of the five pulses output continuously without switching the target wavelength, in a buffer (not shown) for discarding data.

[0102] The data of the fringe waveforms fa5 and fb5 are temporarily stored in a buffer and then discarded. Alternatively, the data may be discarded without being temporarily stored in a buffer. Alternatively, the data may be stored separately as log data in a non-volatile memory (not shown).

[0103] As in S4a of FIG. 10, the spectrum measurement control processor 60 calculates the spectral linewidth based on the spectral waveform. As a result, fringe waveforms fa5 of pulses a5 other than the third number of pulses a1-a4 corresponding to the cumulative pulse number n among five pulses a1-a5 output continuously with the first wavelength λa as the target wavelength are excluded, and the spectral linewidth wa1 is calculated based on the fringe waveforms fa1-fa4 of the third number of pulses a1-a4. Furthermore, fringe waveforms fb5 of pulses b5 other than the fourth number of pulses b1-b4 corresponding to the cumulative pulse number n among five pulses b1-b5 output continuously with the second wavelength λb as the target wavelength are excluded, and the spectral linewidth wb1 is calculated based on the fringe waveforms fb1-fb4 of the fourth number of pulses b1-b4. In this way, the spectral linewidth is calculated for each target wavelength. The third and fourth numbers are, for example, 4.

[0104] The period during which the spectral linewidth wa1 is calculated based on the integrated fringe waveform ia1 stored in the first buffer Bu1 partially overlaps with the period from when the spectrum measurement control processor 60 receives the fringe waveform fb1 of pulse b1 until when it receives the fringe waveform fb4 of pulse b4. Even if these periods partially overlap, the data of the integrated fringe waveform ib1 can be stored in the second buffer Bu2 while the data of the integrated fringe waveform ia1 remains stored in the first buffer Bu1. The period during which the spectral linewidth wb1 is calculated based on the integrated fringe waveform ib1 stored in the second buffer Bu2 partially overlaps with the period from when the spectrum measurement control processor 60 receives the fringe waveform fa6 of pulse a6 until it receives the fringe waveform fa9 of pulse a9. Even though these periods partially overlap, the data of the integrated fringe waveform ia6 can be stored in the first buffer Bu1 while the data of the integrated fringe waveform ib1 remains stored in the second buffer Bu2. Pulse a6 and onwards are similar to pulses a1 to a5, and pulse b6 and onwards are similar to pulses b1 to b5.

[0105] 4.2 Effect (15) According to the third embodiment, one cycle of the periodic change in the target wavelength includes consecutively outputting a first number of pulses a1-a5 having a first wavelength λa and consecutively outputting a second number of pulses b1-b5 having a second wavelength λb. The spectrum measurement control processor 60 calculates a spectral linewidth wa1 based on the fringe waveforms fa1-fa4 of the third number of pulses a1-a4 among the first number of pulses a1-a5, excluding the fringe waveform fa5 of the pulse a5 other than the third number of pulses a1-a4 among the first number of pulses a1-a5. The spectrum measurement control processor 60 calculates a spectral linewidth wb1 based on the fringe waveforms fb1-fb4 of the fourth number of pulses b1-b4 among the second number of pulses b1-b5, excluding the fringe waveform fb5 of the pulse b5 other than the fourth number of pulses b1-b4 among the second number of pulses b1-b5. According to this, pulses output continuously at the same target wavelength have little fluctuation in the fringe waveform, so by using the fringe waveform of such pulses to calculate the spectral linewidth, the spectral linewidths wa1 and wb1 can be calculated appropriately.

[0106] (16) According to the third embodiment, the spectrum measurement control processor 60 discards the excluded fringe waveforms fa5 and fb5. According to this, by discarding the fringe waveforms fa5 and fb5, the required storage area can be reduced.

[0107] (17) According to the third embodiment, the spectrum measurement control processor 60 stores the excluded fringe waveforms fa5 and fb5 separately. According to this, by storing the fringe waveforms fa5 and fb5 that were not used in calculating the spectral linewidth, they can be used for data analysis in the event of a malfunction.

[0108] (18) According to the third embodiment, the spectrum measurement control processor 60 accumulates the fringe waveforms fa1 to fa4 of pulses a1 to a4 having a target wavelength of the first wavelength λa as they are sequentially received, updates the accumulated fringe waveform ia1, and stores the accumulated fringe waveform ia1 in the first buffer Bu1 each time it is updated. The spectrum measurement control processor 60 accumulates the fringe waveforms fb1 to fb4 of pulses b1 to b4 having a target wavelength of the second wavelength λb as they are sequentially received, updates the accumulated fringe waveform ib1, and stores the accumulated fringe waveform ib1 in the second buffer Bu2 each time it is updated. Here, the period during which the spectrum measurement control processor 60 calculates the spectral linewidth wa1 based on the accumulated fringe waveform ia1 stored in the first buffer Bu1 partially overlaps with the period from when the spectrum measurement control processor 60 receives the fringe waveform fb1 of pulse b1 to when it receives the fringe waveform fb4 of pulse b4. This allows the data of the integrated fringe waveform ib1 to be stored in the second buffer Bu2 while the data of the integrated fringe waveform ia1 remains stored in the first buffer Bu1, thereby enabling the calculation of the spectral linewidth wa1 and the accumulation of the fringe waveforms fb1 to fb4 to be performed efficiently. In other respects, the third embodiment is similar to the first embodiment.

[0109] 5.Other The above description is intended to be illustrative rather than limiting. Thus, it will be apparent to one skilled in the art that modifications can be made to the disclosed embodiments without departing from the scope of the claims. It will also be apparent to one skilled in the art that the disclosed embodiments can be used in combination.

[0110] Terms used throughout this specification and claims should be construed as "open ended" unless expressly stated otherwise. For example, words such as "comprise," "have," "comprise," and "equip" should be construed as meaning "without excluding the presence of elements other than those listed." In addition, the modifier "a" should be construed as meaning "at least one" or "one or more." In addition, the term "at least one of A, B, and C" should be construed as "A," "B," "C," "A+B," "A+C," "B+C," or "A+B+C." Furthermore, it should be construed as including combinations of these with elements other than "A," "B," and "C."

Claims

1. a laser oscillator including a wavelength tuning device and outputting a pulsed laser beam having a center wavelength tuned by the wavelength tuning device; a spectrum monitor that generates spectrum data of the pulsed laser light; 1. A processor, comprising: controlling the wavelength tuner so that the center wavelength of the pulsed laser beam changes in accordance with a target wavelength that periodically changes to a plurality of values ​​including a first wavelength and a second wavelength; calculating a first spectral linewidth from spectral data of a plurality of pulses with the first wavelength as the target wavelength; A second spectral linewidth is calculated from the spectral data of a plurality of pulses with the second wavelength as the target wavelength. the processor; A laser device comprising:

2. 2. The laser device according to claim 1, the processor determines whether the spectral data received from the spectrum monitor is spectral data of a pulse having one of the plurality of values ​​as the target wavelength, based on information indicating the control content of the wavelength tuning device by the processor; Laser device.

3. 2. The laser device according to claim 1, The processor: including first and second buffers; storing spectral data of a pulse having the first wavelength as the target wavelength in the first buffer; storing spectral data of a pulse having the second wavelength as the target wavelength in the second buffer; Laser device.

4. 2. The laser device according to claim 1, The processor: including first and second buffers; updating first integrated spectral data by integrating spectral data of a pulse having the first wavelength as the target wavelength each time the spectral data is received, and overwriting and storing the first integrated spectral data in the first buffer each time the first integrated spectral data is updated; updating second integrated spectral data by integrating the spectral data of a pulse having the second wavelength as the target wavelength each time the spectral data is received, and overwriting and storing the second integrated spectral data in the second buffer each time the second integrated spectral data is updated; Laser device.

5. 2. The laser device according to claim 1, The processor: including first and second buffers; updating first integrated spectral data by integrating spectral data of the a1-th to an-th pulses each time the spectral data is sequentially received, the first integrated spectral data being set to the first wavelength as the target wavelength, and storing the first integrated spectral data in the first buffer each time the first integrated spectral data is updated; the spectral data of the b1-th to bn-th pulses having the second wavelength as the target wavelength are accumulated each time the spectral data is sequentially received, to update second accumulated spectral data, and the second accumulated spectral data is stored in the second buffer each time the second accumulated spectral data is updated; a period from when the processor receives the spectral data of the a1 pulse to when it receives the spectral data of the an pulse and a period from when the processor receives the spectral data of the b1 pulse to when it receives the spectral data of the bn pulse partially overlap with each other; Laser device.

6. 2. The laser device according to claim 1, The processor: calculating first integrated spectral data by integrating spectral data of a plurality of pulses with the first wavelength as the target wavelength, and calculating the first spectral linewidth from the first integrated spectral data; calculating second integrated spectral data by integrating spectral data of a plurality of pulses with the second wavelength as the target wavelength, and calculating the second spectral linewidth from the second integrated spectral data; Laser device.

7. 2. The laser device according to claim 1, The processor: calculating first average spectral data by averaging spectral data of a plurality of pulses having the first wavelength as the target wavelength, and calculating the first spectral linewidth from the first average spectral data; calculating second average spectral data by averaging spectral data of a plurality of pulses having the second wavelength as the target wavelength, and calculating the second spectral linewidth from the second average spectral data; Laser device.

8. 2. The laser device according to claim 1, The processor: receiving the spectral data including pulse-by-pulse fringe waveforms from the spectral monitor; calculating a first integrated fringe waveform by integrating fringe waveforms of a plurality of pulses having the first wavelength as the target wavelength, calculating a first spectral waveform from the first integrated fringe waveform, and calculating the first spectral linewidth from the first spectral waveform; calculating a second integrated fringe waveform by integrating fringe waveforms of a plurality of pulses having the second wavelength as the target wavelength, calculating a second spectral waveform from the second integrated fringe waveform, and calculating the second spectral linewidth from the second spectral waveform; Laser device.

9. 2. The laser device according to claim 1, The processor: receiving the spectral data including pulse-by-pulse fringe waveforms from the spectral monitor; calculating a first average fringe waveform by averaging fringe waveforms of a plurality of pulses having the first wavelength as the target wavelength, calculating a first spectral waveform from the first average fringe waveform, and calculating the first spectral linewidth from the first spectral waveform; calculating a second average fringe waveform by averaging fringe waveforms of a plurality of pulses having the second wavelength as the target wavelength, calculating a second spectral waveform from the second average fringe waveform, and calculating the second spectral linewidth from the second spectral waveform; Laser device.

10. 2. The laser device according to claim 1, the processor transmits the spectral line width in the case of the first wavelength and the spectral line width in the case of the second wavelength to an external device without distinguishing between them; Laser device.

11. 2. The laser device according to claim 1, The processor: calculating a first center wavelength from spectrum data of a plurality of pulses with the first wavelength as the target wavelength; calculating a second central wavelength from spectrum data of a plurality of pulses with the second wavelength as the target wavelength; Laser device.

12. 2. The laser device according to claim 1, the laser oscillator is configured to output the pulsed laser light by performing a plurality of burst oscillations including a first burst oscillation and a second burst oscillation performed subsequent to the first burst oscillation, the processor calculates the first and second spectral linewidths by excluding the spectral data of the first pulse of each burst. Laser device.

13. 13. The laser device according to claim 12, the processor discards the excluded spectral data. Laser device.

14. 13. The laser device according to claim 12, the processor separately stores the excluded spectral data. Laser device.

15. 2. The laser device according to claim 1, one cycle of the periodic change of the target wavelength includes successively outputting a first number of pulses of the first wavelength and successively outputting a second number of pulses of the second wavelength; The processor: excluding spectral data of pulses other than a third number of pulses from the first number of pulses, and calculating the first spectral linewidth based on spectral data of the third number of pulses from the first number of pulses; excluding spectral data of pulses other than a fourth number of pulses from the second number of pulses, and calculating the second spectral linewidth based on spectral data of the fourth number of pulses from the second number of pulses; Laser device.

16. 16. The laser device of claim 15, the processor discards the excluded spectral data. Laser device.

17. 16. The laser device of claim 15, the processor separately stores the excluded spectral data. Laser device.

18. 2. The laser device according to claim 1, The processor: including first and second buffers; updating first integrated spectral data by integrating spectral data of the a1-th to an-th pulses each time the spectral data is sequentially received, the first integrated spectral data being set to the first wavelength as the target wavelength, and storing the first integrated spectral data in the first buffer each time the first integrated spectral data is updated; the spectral data of the b1-th to bn-th pulses having the second wavelength as the target wavelength are accumulated each time the spectral data is sequentially received, to update second accumulated spectral data, and the second accumulated spectral data is stored in the second buffer each time the second accumulated spectral data is updated; a period in which the first spectral linewidth is calculated based on the first integrated spectral data stored in the first buffer and a period from when the processor receives the spectral data of the b1 pulse to when the processor receives the spectral data of the bn pulse partially overlap each other; Laser device.

19. changing the central wavelength of the pulsed laser beam in accordance with a target wavelength that periodically varies among a plurality of values ​​including a first wavelength and a second wavelength; calculating a first spectral linewidth from spectral data of a plurality of pulses with the first wavelength as the target wavelength; A second spectral linewidth is calculated from the spectral data of a plurality of pulses with the second wavelength as the target wavelength. A method for measuring spectral linewidth, including:

20. A method for manufacturing an electronic device, comprising: a laser oscillator including a wavelength tuning device and outputting a pulsed laser beam having a center wavelength tuned by the wavelength tuning device; a spectrum monitor that generates spectrum data of the pulsed laser light; 1. A processor, comprising: controlling the wavelength tuner so that the center wavelength of the pulsed laser beam changes in accordance with a target wavelength that periodically changes to a plurality of values ​​including a first wavelength and a second wavelength; calculating a first spectral linewidth from spectral data of a plurality of pulses with the first wavelength as the target wavelength; A second spectral linewidth is calculated from the spectral data of a plurality of pulses with the second wavelength as the target wavelength. the processor; The pulsed laser light is generated by a laser device comprising: outputting the pulsed laser light to an exposure device; In order to manufacture the electronic device, a photosensitive substrate is exposed to the pulsed laser light in the exposure apparatus. A method for manufacturing an electronic device, comprising:

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