Method for evaluating deterioration of line sensor, spectrum measuring apparatus, and computer-readable medium

Abstract

A method for assessing degradation of a line sensor, the method comprising: detecting an interference pattern of pulsed laser light using a line sensor; calculating an assessment value that serves as an index for degradation and storing the assessment value in a storage device, for each of a plurality of sensor channels included in at least a partial sensor channel range of the line sensor or for each group of sensor channels, on the basis of signal values obtained from the sensor channels and depending on the light intensity of an interference pattern, and storing the assessment values in a storage device; and determining a degradation state of the line sensor on the basis of the assessment values.

Description

Technical Field

[0001] The present disclosure relates to a method for evaluating deterioration of a line sensor, a spectrum measuring apparatus, and a computer-readable medium.

Background Art

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

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

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

[0005] A method for evaluating the deterioration of a line sensor according to one aspect of the present disclosure includes detecting interference fringes of pulsed laser light using the line sensor, calculating an evaluation value serving as an index of deterioration for each sensor channel or for each group of sensor channels based on signal values obtained from each of a plurality of sensor channels included in at least a part of the sensor channel range of the line sensor according to the light intensity of the interference fringes, storing the evaluation value in a storage device, and determining the deterioration state of the line sensor based on the evaluation value.

[0006] A spectral measurement apparatus according to another aspect of the present disclosure includes an optical system that generates interference fringes when pulsed laser light is incident thereon, a line sensor that detects the interference fringes, and a processor that processes information obtained from the line sensor. The processor calculates an evaluation value serving as an index of deterioration for each sensor channel or for each group of sensor channels based on signal values obtained from each of a plurality of sensor channels included in at least a part of the sensor channel range of the line sensor according to the light intensity of the interference fringes, stores the evaluation value in a storage device, and determines the deterioration state of the line sensor based on the evaluation value.

[0007] A computer-readable medium according to another aspect of the present disclosure is a non-transitory computer-readable medium that records a program for causing a processor to execute a process of acquiring a signal output from a line sensor that detects interference fringes of pulsed laser light, a process of calculating an evaluation value serving as an index of deterioration for each sensor channel or for each group of sensor channels based on signal values obtained from each of a plurality of sensor channels included in at least a part of the sensor channel range of the line sensor according to the light intensity of the interference fringes, storing the evaluation value in a storage device, and a process of determining the deterioration state of the line sensor based on the evaluation value.

Brief Description of the Drawings

[0008] Some embodiments of the present disclosure will be described below by way of example only with reference to the accompanying drawings.

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[0009] -Table of Contents- 1. Description of Terms and Technologies 1.1 Principle of Etalon Spectrometer 1.2 Calculation of Measurement Wavelength 1.3 Explanation of Fringe Order MavEx 2. Overview of Laser Device According to Comparative Example 1 2.1 Configuration 2.2 Operation 3. Overview of Laser Device According to Comparative Example 2 3.1 Configuration 3.2 Operation 4. Problems 5. Embodiment 1 5.1 Configuration 5.2 Operation 5.3 Function and Effect 6. Embodiment 2 6.1 Configuration 6.2 Operation 6.3 Function and Effect 7. Embodiment 3 7.1 Configuration 7.2 Operation 7.3 Function and Effect 8. Embodiment 4 8.1 Configuration 8.2 Operation 8.3 Function and Effect 9. Embodiment 5 9.1 Configuration 9.2 Operation 9.3 Function and Effect 10. Embodiment 6 10.1 Configuration 10.2 Operation 10.3 Function and Effect 11. Other Examples of Laser Devices 12. Regarding Computer-Readable Media Recorded with a Program 13. Manufacturing Method of Electronic Devices 14. Others 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. Also, not all of the configurations and operations described in each embodiment are essential as the configurations and operations of the present disclosure. The same reference numerals are assigned to the same components, and duplicate descriptions are omitted.

[0010] 1. Explanation of Terms and Technologies 1.1 Principle of Etalon Spectrometer FIG. 1 is a schematic diagram showing a schematic configuration of an etalon spectrometer 10. As shown in FIG. 1, the etalon spectrometer 10 includes a diffusing element 12, an FP (Fabry - Perot) etalon 14, a condenser lens 16, and a line sensor 18. The line sensor 18 may be a linear image sensor or a photodiode array.

[0011] The laser light is incident on the diffusing element 12. The diffusing element 12 scatters the incident laser light. This scattered light is incident on the FP etalon 14. The laser light transmitted through the FP etalon 14 is incident on the condenser lens 16. The laser light passes through the condenser lens 16 and generates interference fringes on the focal plane. The line sensor 18 is disposed on the focal plane of the condenser lens 16 having a focal length f. The transmitted light collected by the condenser lens 16 generates interference fringes (fringes) at the position of the line sensor 18. The line sensor 18 detects the light intensity of the interference fringes generated by the FP etalon 14.

[0012] FIG. 2 shows an example of detecting the light intensity of the interference fringe IF using the line sensor 18. The upper part of FIG. 2 shows a plan view showing the positional relationship between the interference fringe IF and the line sensor 18, and the lower part of FIG. 2 shows an example of a detection signal obtained from the line sensor 18. The horizontal axis represents the position, for example, it may be the sensor channel number indicating the position of each light receiving element (sensor channel) of the line sensor 18. The vertical axis represents the light intensity of the detected interference fringe IF. For example, it may be the digital signal value of the detection signal output from each sensor channel, or it may be a value normalized with the maximum value in the intensity distribution as "1".

[0013] As shown in FIG. 2, high light intensity is detected at the position where the interference fringe IF hits the detection surface (light receiving surface) of the line sensor 18. The interference fringe IF shown in FIG. 2 has concentric circular rings indicated by solid lines representing the peak positions (bright parts) of the light intensity. The waveform showing the light intensity distribution of the interference fringe IF as shown in the lower part of FIG. 2 is called a fringe waveform. In the following description, the center of the interference fringe IF is called the "fringe center". Also, each bright part of the interference fringe IF is called a "fringe", and the fringes are numbered from the inside to distinguish each fringe, with the fringe closest to the fringe center being the 1st and the outside being the 2nd.

[0014] 1.2 Calculation of Measurement Wavelength Generally, the interference fringe of an etalon is represented by the following formula (1).

[0015]

Equation

[0016] As in formula (1), the radius r of the interference fringe mThe square is proportional to the wavelength λ of the laser beam. Therefore, the spectral linewidth (spectral profile) and the central wavelength of the entire laser beam can be detected from the detected interference fringes. The spectral linewidth and the central wavelength may be obtained by an information processing device (not shown) from the detected interference fringes, or may be calculated by a wavelength control unit (for example, the wavelength control unit 60 in FIG. 3).

[0017] FIG. 3 is a graph showing an example of the light intensity distribution of the interference fringes detected by the line sensor 18, where the horizontal axis represents the position on the detection surface and the vertical axis represents the light intensity I. The radius r of the interference fringe m The square of may be calculated from the average value of the square of the radius r1 inside the position of the half value of the interference fringe and the square of the radius r2 outside. That is, the radius r of the interference fringe m The square of may be obtained from the following formula (2).

[0018] r m 2 =(r1 2 +r2 2 ) / 2 ···(2) The half value of the interference fringe refers to the half value (50% intensity) Imax / 2 of the peak intensity Imax of the fringe peak in the waveform showing the intensity distribution.

[0019] 1.3 Explanation of the fringe order MavEx As described above, the wavelength λ of the laser beam is proportional to the square of the radius r of the interference fringe m There is a fringe order as an index representing the relative position of the fringe peak in the wavelength space by using this relationship. The fringe order is calculated as follows.

[0020] First, in the same manner as in FIG. 3, as shown in FIG. 4, the sensor channel positions (both inside and outside) corresponding to 50% of the height are calculated from the respective intensity peaks of the two innermost fringes. The sensor channel positions corresponding to 50% of the height of the intensity peak are calculated by linear interpolation of the two actual channels before and after. Half of the distance between the two inner 50% heights of the two fringes is r 11 , and half of the distance between the two outer 50% heights is r 21 Let, r11 and r 21 Calculate them and calculate the radius r from the following formula (3): m1 as follows.

[0021] r m1 2 = (r 11 2 + r 21 2 ) / 2 ···(3) Similarly, as shown in FIG. 5, from the sensor channel positions (both inside and outside) corresponding to 50% of the height of each intensity peak of the two inner second fringes, take half of the distance between the inner halves at 50% height as r 12 , take half of the distance between the outer halves at 50% height as r 22 and calculate r 12 and r 22 and calculate the radius r from the following formula (4): m2 as follows.

[0022] r m2 2 = (r 12 2 + r 22 2 ) / 2 ···(4) Here, for an arbitrary distance r from the fringe center, if the fringe order at that position is MavEx, then MavEx is defined by the following formula (5).

[0023] MavEx = r 2 / (r m2 2 - r m1 2 )···(5) As shown in FIG. 6, assuming that MavEx at r = r m1 is 0.21, then MavEx at r = r m2 is 1.21. Thus, the difference in fringe order between adjacent fringes is always 1.

[0024] For example, in the range of the left half from the fringe center, there is only one fringe with a MavEx value between 0.5 and 1.5, which is the fringe with MavEx = 1.21. Due to this property of the fringe order, it becomes possible to select fringes within a specific range to calculate the central wavelength and spectral linewidth. FIG. 7 shows an example of the spectral measurement waveform obtained from the fringe with MavEx = 1.21. The horizontal axis in FIG. 7 represents the wavelength, and the vertical axis represents the optical intensity.

[0025] 2. Overview of the laser device according to Comparative Example 1 2.1 Configuration FIG. 8 is a diagram schematically showing the configuration of a laser device 101 according to Comparative Example 1. The comparative example of the present disclosure is a form recognized by the applicant as being known only to the applicant and is not a publicly known example recognized by the applicant. As shown in FIG. 8, the laser device 101 is a narrow-band gas laser device including a chamber 20, a power supply 26, an output coupling mirror 30, a narrow-band module 32, a monitor module 40, a wavelength control unit 60, a laser control unit 61, and a driver 62.

[0026] The output coupling mirror 30 and the narrow-band module 32 constitute a laser resonator. The chamber 20 is disposed on the optical path of the laser resonator. The narrow-band module 32 includes a plurality (for example, two) of prisms 34, a grating 36, and a rotary stage 38.

[0027] The prism 34 is arranged to function as a beam expander. The grating 36 is retrofitted so that the incident angle and the diffraction angle coincide. The prism 34 is installed on the rotary stage 38, and is arranged such that the incident angle to the grating 36 changes as the prism 34 rotates by the rotary stage 38.

[0028] The chamber 20 includes windows 22a, 22b and a pair of electrodes 24a, 24b. The chamber 20 houses a laser gas inside. The laser gas may include, for example, Ar gas or Kr gas as a rare gas, F2 gas as a halogen gas, and Ne gas as a buffer gas.

[0029] The electrodes 24a and 24b face each other in a direction (V direction) perpendicular to the plane of the drawing in FIG. 8 within the chamber 20, and are arranged such that the longitudinal direction of the electrodes 24a and 24b coincides with the direction of the optical path of the laser resonator. The electrodes 24a and 24b are connected to a power supply 26.

[0030] The power supply 26 includes a switch 28, and when the switch 28 is turned on, a high voltage is applied between the electrodes 24a and 24b in the chamber 20.

[0031] The windows 22a and 22b are arranged such that the laser light amplified by discharge excitation between the electrodes 24a and 24b passes through.

[0032] The output coupling mirror 30 is coated with a film that reflects a part of the laser light and transmits the other part.

[0033] The monitor module 40 includes a beam splitter 41, a beam splitter 42, a condenser lens 43, a pulse energy monitor 44, a sealed chamber 45, a line sensor 52, and a line sensor 53.

[0034] The beam splitter 41 is arranged on the optical path of the laser light output from the output coupling mirror 30 such that the laser light reflected by the beam splitter 41 is incident on the beam splitter 42. The laser light transmitted through the beam splitter 41 is emitted from the laser device 101. The exposure device 302 is arranged such that the laser light emitted from the laser device 101 is incident thereon.

[0035] The beam splitter 42 is arranged on the optical path of the laser light reflected by the beam splitter 41 such that the laser light reflected by the beam splitter 42 is incident on the pulse energy monitor 44. The pulse energy monitor 44 may be a photodiode, a phototube, or a pyroelectric element.

[0036] The condenser lens 43 is arranged such that the laser light transmitted through the beam splitter 42 is incident thereon.

[0037] The sealed chamber 45 includes a diffusion plate 46, a fine etalon 47, a coarse etalon 48, a beam splitter 49, a condenser lens 50, and a condenser lens 51.

[0038] The diffusion plate 46 is disposed near the condensing position of the condenser lens 43. The diffusion plate 46 is an optical element made of synthetic quartz with one side being flat and the other side being processed into a striated glass shape. The diffusion plate 46 is sealed to the sealed chamber 45 with an O-ring (not shown).

[0039] The fine etalon 47 is disposed such that the laser light transmitted through the diffusion plate 46 is incident through the beam splitter 49. The beam splitter 49 is disposed on the optical path between the diffusion plate 46 and the fine etalon 47 such that the laser light partially reflected by the beam splitter 49 is incident on the coarse etalon 48. The fine etalon 47 and the coarse etalon 48 may each be an air-gap etalon in which two mirrors each coated with a partial reflection film are joined via a spacer.

[0040] The free spectral range FSRf of the fine etalon 47 and the free spectral range FSRc of the coarse etalon 48 satisfy the relationship of the following formula (6).

[0041] FSRf < FSRc ···(6) The free spectral range FSR is represented by the following formula (7).

[0042] FSR = λ 2 / (2nd) ···(7) Generally, assuming the finesse of the etalon is F, the resolution R is expressed as R = FSR / F. When the finesse F is the same, as the FSR decreases, the resolution R increases. However, when the FSR decreases, when the wavelength changes by the amount of the FSR, the interference fringes are substantially the same, so it is impossible to distinguish in the measurement using a single etalon with a small FSR.

[0043] Therefore, when changing the wavelength by about 400 pm like an excimer laser and measuring the wavelength with high precision, the interference fringes of the fine etalon 47 and the coarse etalon 48 are measured by the line sensor 52 and the line sensor 53 respectively, so that the wavelength can be measured with high precision. The FSRf of the fine etalon 47 may be, for example, FSRf = 10 pm, and the FSRc of the coarse etalon 48 may be, for example, FSRc = 400 pm.

[0044] The condenser lens 50 is disposed on the optical path of the laser beam transmitted through the fine etalon 47 and is sealed in the sealed chamber 45 with an O-ring (not shown). The condenser lens 51 is disposed on the optical path of the laser beam transmitted through the coarse etalon 48 and is sealed in the sealed chamber 45 with an O-ring (not shown). The focal length of the condenser lens 51 is shorter than the focal length of the condenser lens 50.

[0045] The line sensor 52 and the line sensor 53 are respectively disposed at the positions of the focal planes of the condenser lens 50 and the condenser lens 51. Each of the line sensor 52 and the line sensor 53 has a plurality of light receiving elements arranged in one dimension and outputs a detection signal corresponding to the light intensity of the received interference fringe. Each of the line sensor 52 and the line sensor 53 is equipped with a signal processing circuit including an A / D converter that converts the detection signal corresponding to the amount of received light into digital data. The amount of light detected by each light receiving element of the line sensors 52 and 53 is output from the line sensors 52 and 53 as a signal value represented by a digital value of, for example, 12 bits.

[0046] The light receiving element corresponds to a "pixel", and each of the plurality of light receiving elements is called a sensor channel. The position on the detection surface of the interference fringe can be represented by a sensor channel number indicating the position of the sensor channel.

[0047] The interference fringe of the etalon is represented by equations (1) to (8).

[0048] mλ = 2nd·cosθ ···(8) The wavelength control unit 60 is communicably configured with the line sensor 52, the line sensor 53, the laser control unit 61, and the driver 62. The wavelength control unit 60 and the laser control unit 61 are realized using a processor. The processor in the present disclosure is a processing device including a storage device storing a control program and a CPU (Central Processing Unit) that executes the control program. The processor is specially configured or programmed to execute various processes included in the present disclosure. A configuration may be provided with a processor functioning as the wavelength control unit 60 and a processor functioning as the laser control unit 61 separately, or both functions may be realized by one processor.

[0049] The laser control unit 61 is communicably configured with the power supply 26, the switch 28, the pulse energy monitor 44, and the exposure device control unit 310 of the exposure device 302. The driver 62 is communicably configured with the rotary stage 38.

[0050] 2.2 Operation The laser control unit 61 reads data on the target pulse energy Et and the target wavelength λt from the exposure device control unit 310. The laser control unit 61 transmits a charging voltage V to the power supply 26 and transmits the target wavelength λt to the wavelength control unit 60 so that the pulse energy of the pulsed laser light becomes the target pulse energy Et and the oscillation wavelength becomes the target wavelength λt. The laser control unit 61 turns on the switch 28 based on the oscillation trigger transmitted from the exposure device control unit 310.

[0051] When the switch 28 is turned on, a high voltage is applied between the electrodes 24a and 24b, and a discharge occurs to excite the laser gas. When the laser gas is excited, laser oscillation occurs in a laser resonator composed of the narrowbanding module 32 and the output coupling mirror 30, and narrowbanded pulsed laser light is output from the output coupling mirror 30.

[0052] The pulsed laser light output from the output coupling mirror 30 and sampled by the beam splitter 41 is incident on the beam splitter 42. The reflected light of the beam splitter 42 is incident on the pulse energy monitor 44, and the transmitted light of the beam splitter 42 is incident on the diffusion plate 46 of the sealed chamber 45.

[0053] Based on the detection result of the pulse energy monitor 44, the laser control unit 61 controls the charging voltage V of the power supply 26 so that the pulse energy of the pulsed laser light becomes the target pulse energy Et.

[0054] On the other hand, the wavelength control unit 60 measures the light intensity distribution of each interference fringe generated by the coarse etalon 48 and the fine etalon 47 for each pulse by the line sensor 53 and the line sensor 52, and reads the data. The wavelength control unit 60 calculates the measured wavelength λ of the pulsed laser light for each pulse from the data of the light intensity distribution of the interference fringe read for each pulse. The calculation of the measured wavelength λ may be performed from data obtained by integrating or averaging over a plurality of pulses rather than for each pulse. Based on the measured wavelength λ, the wavelength control unit 60 controls the rotation stage 38 of the prism 34 via the driver 62 so that the oscillation wavelength of the pulsed laser light becomes the target wavelength λt.

[0055] As described above, the pulse energy and the oscillation wavelength of the laser device 101 are stabilized to the target pulse energy Et and the target wavelength λt given by the exposure device 302. Here, since the sealed chamber 45 is sealed, the difference in the refractive index n of the air gap in Equation (1) in each of the coarse etalon 48 and the fine etalon 47 is suppressed to be small, and the error in wavelength measurement due to the drift of the coarse etalon 48 and the fine etalon 47 is reduced.

[0056] 3. Outline of the laser device according to Comparative Example 2 3.1 Configuration FIG. 9 is a diagram schematically showing the configuration of the laser device 102 according to Comparative Example 2. The differences from FIG. 8 in the configuration shown in FIG. 9 will be described. The laser device 102 shown in FIG. 9 includes a grating spectrometer instead of the coarse etalon 48 in FIG. 8. By measuring the wavelength range corresponding to FSRc using the grating spectrometer and simultaneously measuring the interference fringes with the fine etalon 47, both can cooperate to measure a wide range of wavelengths with high precision. The laser device 102 includes a beam splitter 70, an aperture 71, a mirror 72, a collimating lens 73, and a coarse grating 74.

[0057] The beam splitter 70 is disposed on the optical path of the laser beam that has passed through the condenser lens 43. The aperture 71 is disposed near the focusing position of the condenser lens 43 so that the laser beam reflected by the beam splitter 70 is incident thereon.

[0058] The mirror 72 is disposed so that the laser beam that has passed through the aperture 71 is incident thereon. The collimating lens 73 is disposed so that the laser beam reflected by the mirror 72 is incident thereon. The coarse grating 74 is disposed so as to reflect the laser beam incident from the collimating lens 73 back toward the collimating lens 73.

[0059] The line sensor 53 is disposed so that the laser beam reflected by the coarse grating 74 and passing through the collimating lens 73 is incident thereon. The other configurations may be the same as those in FIG. 8.

[0060] 3.2 Operation The pulsed laser beam output from the output coupling mirror 30 and sampled by the beam splitter 41 is incident on the beam splitter 42. The transmitted light of the beam splitter 42 passes through the condenser lens 43 and is incident on the beam splitter 70.

[0061] The reflected light of the beam splitter 70 is incident on the aperture 71. The transmitted light of the beam splitter 70 is incident on the diffuser plate 46 of the sealed chamber 45.

[0062] The pulsed laser light that has passed through the aperture 71 is reflected by the mirror 72, collimated by the collimating lens 73, and incident on the coarse grating 74. The pulsed laser light diffracted by the coarse grating 74 passes through the collimating lens 73 and generates interference fringes at the position of the light receiving surface of the line sensor 53.

[0063] As described above, according to the laser device 102, it is possible to measure the wavelength range corresponding to the free spectral range FSRc of the coarse etalon 48 by the grating spectrometer. Therefore, similar to the laser device 101, the laser device 102 shown in FIG. 9 can measure a wide range of wavelengths with high precision by measuring each pulse by the line sensor 53 and the line sensor 52 in cooperation.

[0064] 4. Problems The line sensors 52 and 53 of the monitor module 40 have a limited lifespan. The line sensors 52 and 53 deteriorate due to long-term use, and the sensor sensitivity decreases.

[0065] FIG. 10 is a graph showing an example of detecting a free spectrum using the line sensor 52 in a non-degraded state. FIG. 11 is a graph showing an example of detecting a free spectrum using the line sensor 52 including a degraded sensor channel. In FIGS. 10 and 11, the horizontal axis represents the sensor channel number of the line sensor 52, and the vertical axis represents the measured value of the light intensity.

[0066] As is clear from comparing FIG. 10 and FIG. 11, the sensor sensitivity of the degraded sensor channel decreases, making it difficult to obtain accurate measurement values. Such a phenomenon is not limited to the line sensor 52, but is the same for other line sensors such as the line sensor 53. The degree of degradation (the degree of decrease in sensor sensitivity) of each sensor channel is related to the cumulative amount of irradiation energy of the pulsed laser light irradiated to each sensor channel. The cumulative amount of irradiation energy of the pulsed laser light irradiated to each sensor channel may also be referred to as the light receiving integration amount of each sensor channel.

[0067] In the laser devices 101 and 102 shown in Comparative Example 1 and Comparative Example 2, the monitor module 40 that was used beyond a predetermined number of shots (shot limit) assumed in anticipation of this deterioration was uniformly replaced.

[0068] However, depending on the usage situation of the monitor module 40 and the individual differences of the line sensors 52 and 53, even if used beyond the shot limit, the linearity error is within an acceptable range, and it has been found that there are many that can be used sufficiently.

[0069] Therefore, in a field such as a semiconductor manufacturing factory, it is economically desirable to evaluate the deterioration of the uniformity of the sensor sensitivity of the line sensors 52 and 53 or the measurement linearity error of the etalon measuring instrument, and replace only the problematic monitor module 40. For this reason, a strategy for evaluating the individual deterioration status of the line sensors 52 and 53 and determining the necessity of replacement has been desired.

[0070] 5. Embodiment 1 5.1 Configuration FIG. 12 schematically shows the configuration of a laser device 110 including a spectrum measurement device 150 according to Embodiment 1. Regarding the configuration shown in FIG. 12, the differences from FIG. 8 will be described. In the laser device 110, a sensor data management unit 160 is added to the wavelength control unit 60 of FIG. 8. The sensor data management unit 160 is also realized using a processor, similar to the wavelength control unit 60 and the laser control unit 61. The sensor data management unit 160 includes a counter 162, an arithmetic unit 164, and a storage unit 166. The spectrum measurement device 150 includes a monitor module 40 and a wavelength control unit 60. Other configurations may be the same as those in FIG. 8. Note that the sensor data management unit 160 may be added to the wavelength control unit 60 of FIG. 9.

[0071] 5.2 Operation The operation of the sensor data management unit 160 will be described. Here, the deterioration evaluation method will be exemplified by taking the line sensor 52 as an example, but the deterioration evaluation methods for other line sensors such as the line sensor 53 are the same.

[0072] [Step 1A] The sensor data management unit 160 integrates the number of times the light amount of the fringe pattern exceeds the threshold value for each sensor channel of the line sensor 52, and stores the count value for each sensor channel in the storage unit 166 within the sensor data management unit 160. For example, if the digital output standard of each sensor channel of the line sensor 52 is 12 bits, the signal value output from the sensor channel indicating the light amount measurement value can be a value from 0 to 4095. In this case, in order to increase the signal-to-noise ratio so that the signal value does not saturate, the signal value is often adjusted so that the fringe peak value becomes 2000 - 3000.

[0073] FIG. 13 shows an example of the fringe waveform of the first pulse obtained under the condition that the fringe peak value becomes 2000 - 3000. Here, an example is shown in which the light amount threshold Th1 is set to 2000, and the number of times is counted for each sensor channel only when the light amount exceeds this light amount threshold Th1. The light amount threshold Th1 set to 2000 is an example of the "first threshold value" in the present disclosure. FIG. 13 is an example of the fringe waveform detected using the line sensor 52 having 448 channels. In FIG. 13, the fringe peaks exceeding the light amount threshold Th1 are indicated by being surrounded by broken-line circles.

[0074] The chart shown in FIG. 14 shows an example of the count value for each sensor channel when only the sensor channels exceeding the light amount threshold Th1 (= 2000) in the fringe waveform of the first pulse are counted. "1" is counted for the sensor channels in which the light amount exceeding the light amount threshold Th1 is detected.

[0075] Subsequently, for the fringe waveform of the second pulse, similarly, only the sensor channels that exceed the light quantity threshold Th1 are counted and added to the previously recorded (previous) count value. FIG. 15 is an example of the fringe waveform of the second pulse detected on the same 448-channel line sensor 52. In FIG. 15, the sensor channel numbers where the light quantity exceeding the light quantity threshold Th1 is detected are 64, 174, 175, 272, 273, and 342. In this case, as shown in FIG. 16, at the end of the second pulse, "1" is added to the previous (in FIG. 14) count value for these sensor channel numbers, and the count value is updated.

[0076] In this way, the sensor data management unit 160 accumulates the number of times exceeding the light quantity threshold Th1 for each sensor channel. This count value is used as an index (evaluation index of local degradation) for quantitatively evaluating the local degradation due to the cumulative light reception of each sensor channel. The larger the count value, the greater the degree of degradation can be evaluated. The count value is an example of the "evaluation value" in the present disclosure.

[0077] The accumulation for each sensor channel that exceeds the light quantity threshold Th1 may be performed not for all pulses but for every certain number of pulses. For example, the accumulation for each sensor channel that exceeds the light quantity threshold Th1 may be performed at a frequency of 1 pulse for every 10 pulses.

[0078] Also, the accumulation of the sensor channels that exceed the light quantity threshold Th1 may be performed not only for the fringe waveform obtained by 1 pulse but also for the fringe waveform obtained by integrating a certain number of pulses. For example, the accumulation of the sensor channels that exceed the light quantity threshold Th1 may be performed for one fringe waveform obtained by integrating 10 pulses of irradiation.

[0079] Regarding the determination of whether the light quantity exceeds the light quantity threshold Th1, it is not limited to the mode of directly comparing the light quantity measurement values detected by each sensor channel as shown in FIG. 17 with the light quantity threshold Th1. For example, as shown in FIG. 18, the average value of the background noise of the line sensor 52 is obtained in advance, and after subtracting the average value of the background noise (FIG. 18) from the light quantity measurement value (FIG. 17) detected by each sensor channel, a determination may be made as to whether the fringe waveform (see FIG. 19) exceeds the light quantity threshold Th1. The average value of the background noise is an example of the "third constant" in the present disclosure.

[0080] [Step 2A] The arithmetic unit 164 of the sensor data management unit 160 calculates the maximum value for the count values of each sensor channel counted by the means in Step 1A each time. Alternatively, the maximum value, minimum value, and average value are calculated each time, and the difference between the maximum value and the minimum value or the difference between the maximum value and the average value is calculated each time. The "each time" here means every time the data of the fringe light quantity is read from the line sensor 52. When the data is read once per pulse, it means each time in the unit of one pulse. When the data is read once from the line sensor 52 by integrating a certain number of pulses, it means each time in the unit of a certain number of pulses.

[0081] [Step 3A] The sensor data management unit 160 sets a threshold Th2 for the maximum value of the count value obtained by the means in Step 2A. When the maximum value exceeds the threshold Th2, it is determined that the line sensor 52 is a deteriorated sensor from which an accurate fringe pattern cannot be obtained. For example, when the threshold Th2 for the maximum value of the count value is set to 50,000,000,000 (50 billion), as shown in FIG. 20, when the maximum value of the count value for each sensor channel recorded in the sensor data management unit 160 exceeds 50 billion, it is determined that the line sensor 52 is in a deteriorated state from which an accurate fringe pattern cannot be obtained.

[0082] Regarding the method of threshold determination applied to this maximum value, it may also be applied to the value of the difference between the maximum value and the minimum value or the value of the difference between the maximum value and the average value. The threshold Th2 set to 50 billion is an example of the "second threshold" in the present disclosure.

[0083] [Step 4A] When the value counted in Step 2A or the determination threshold Th2 causes an overflow, the counted value or the threshold Th2 may use a value divided by a certain numerical value. For example, the threshold Th2 illustrated in Step 3A may be a value obtained by dividing 50 billion by 1,000,000, that is, 50,000. In this case, for the count value recorded for each sensor channel of the line sensor 52, similarly, the value divided by 1,000,000 is integrated, and the maximum value, or the difference between the maximum value and the minimum value, or the difference between the maximum value and the average value may be calculated to perform threshold determination. The divisor 1,000,000 is an example of the "first constant" in the present disclosure.

[0084] [Step 5A] The count value of each sensor channel and the result of threshold determination may be displayed by a user interface that monitors the operating status of the laser device 110. For example, a processor functioning as the sensor data management unit 160 may be connected to a display device (not shown), and the display device may be configured to display the count value and the result of threshold determination.

[0085] [Step 6A] When the value used for threshold determination (in the case of Embodiment 1, the count value) exceeds the threshold Th2, a warning may be displayed on the user interface in Step 5A, or the occurrence of the warning may be recorded in a log. The sensor data management unit 160 may execute at least one of the processes of displaying the determination result on a display device, recording the determination result in a log, and performing notification based on the determination result.

[0086] <Others> The above operation has been described using the fringe pattern formed by the etalon spectrometer. However, the same operation may be performed not only for the etalon spectrometer but also for the grating spectrometer. In addition, although examples using the etalon spectrometer will be described for Embodiments 2 to 6 below, the same operations as those in Embodiments 2 to 6 may be performed for the grating spectrometer. The etalon spectrometer and the grating spectrometer are examples of the "optical system" in the present disclosure.

[0087] 5.3 Action and Effect According to Embodiment 1, since it is possible to detect a decrease in the sensitivity of a specific sensor channel in the line sensors 52 and 53, it becomes possible to replace the line sensor 52 or the line sensor 53 or the monitor module 40 that is deteriorating while the influence is small. As a result, it is possible to maintain a state in which the wavelength and the spectral line width can be appropriately measured.

[0088] In addition, according to Embodiment 1, since replacement can be carried out after detecting that the line sensors 52 and 53 are actually in a deteriorated state, it is economically advantageous compared to the case of uniformly replacing based on the shot limit.

[0089] 6. Embodiment 2 6.1 Configuration The configuration of Embodiment 2 may be the same as that of Embodiment 1 shown in FIG. 12.

[0090] 6.2 Operation Differences from Embodiment 1 will be described. In Embodiment 1, the number of times the signal value (value corresponding to the amount of light) of each sensor channel output according to the light intensity of the interference fringes exceeds the light amount threshold Th1 was counted for each sensor channel. In Embodiment 2, the signal values of each sensor channel are integrated for each sensor channel, and the deterioration status is evaluated using the integrated light amount value. The sensor data management unit 160 in Embodiment 2 operates as follows.

[0091] [Step 1B] The sensor data management unit 160 integrates the light amount of the fringe pattern for each sensor channel in the line sensor 52, and stores the integrated light amount value for each sensor channel in the storage unit 166 within the sensor data management unit 160. For example, FIG. 21 shows the fringe waveform of the first pulse detected on the line sensor 52 with 448 sensor channels, and the integrated light amount values of the 101st to 110th sensor channels of the sensor channel number at the end of the first pulse are as shown in FIG. 22.

[0092] Subsequently, when the fringe waveform of the second pulse detected on the same 448-channel line sensor 52 is obtained as a graph as shown in FIG. 23, the light amount of the second pulse in each of the 101st to 110th sensor channels is as shown in FIG. 24. However, in the sensor data management unit 160, the integrated light amount value obtained by integrating the light amounts of the first and second pulses is stored. At the end of the second pulse, the integrated light amount values in each of the 101st to 110th sensor channels are as shown in FIG. 25. In this way, for each sensor channel, the integrated value of the detected fringe light amount is managed by the sensor data management unit 160. The integrated light amount value is an example of the "evaluation value" in the present disclosure.

[0093] The integration of the light amount may be performed not for all pulses but for every certain number of pulses. For example, the light amount integration for each sensor channel may be performed at a frequency of one pulse every 10 pulses.

[0094] Also, the integration of the light amount may be performed not only on the fringe waveform obtained by one pulse but also on the fringe waveform obtained by integrating a certain number of pulses. For example, the light amount integration for each sensor channel may be performed on one fringe waveform obtained by integrating the irradiation of 10 pulses.

[0095] Also, the integration of the light amount may be performed on the fringe waveform after subtracting the average value of the background noise calculated in advance.

[0096] [Step 2B] The arithmetic unit 164 of the sensor data management unit 160 calculates the maximum value for the light quantity integrated value of each sensor channel integrated by the means in Step 1B every time. Alternatively, for the light quantity integrated value of each sensor channel, the maximum value, minimum value, and average value are calculated every time, and the difference between the maximum value and the minimum value, or the difference between the maximum value and the average value is calculated every time.

[0097] [Step 3B] The sensor data management unit 160 sets a threshold value Th3 for the maximum value of the light quantity integrated value obtained by the means in Step 2B, and when the maximum value of the light quantity integrated value exceeds the threshold value Th3, it determines that the line sensor 52 is a sensor from which an accurate fringe pattern cannot be obtained.

[0098] FIG. 26 is a graph showing an example of the light quantity integrated value for each sensor channel when 50 billion pulses are reached. For example, when the threshold value Th3 of the light quantity integrated value is set to 100,000,000,000,000 (100 trillion), as shown in FIG. 26, when the maximum value of the light quantity integrated value for each sensor channel recorded in the sensor data management unit 160 exceeds 100 trillion, it is determined that an accurate fringe pattern cannot be obtained for the line sensor 52.

[0099] Regarding the method of threshold determination applied to this maximum value, it may also be applied to the difference between the maximum value and the minimum value, or the difference between the maximum value and the average value. The threshold value Th3 set to 100 trillion is an example of the "second threshold value" in the present disclosure.

[0100] [Step 4B] In step 3B, if the light amount integration value in step 2B or the determination threshold Th3 causes an overflow, the integrated light amount value or the threshold Th3 may be a value divided by a certain numerical value. For example, the determination threshold Th3 for the light amount integration value in step 2B may be a value obtained by dividing 100 trillion by 1,000,000,000, that is, 100,000. Similarly, for the light amount integration value recorded for each sensor channel of the line sensor 52, a value divided by 1,000,000,000 may be recorded, and threshold determination may be performed by calculating the maximum value, or the difference between the maximum value and the minimum value, or the difference between the maximum value and the average value. The divisor 1,000,000,000 is an example of the "second constant" in the present disclosure.

[0101] [Step 5B] The light amount integration value of each sensor channel and the result of the threshold determination may be displayed by a user interface that monitors the operating status of the laser device 110.

[0102] [Step 6B] When the value used for threshold determination (in the case of Embodiment 2, the light amount integration value) exceeds the threshold Th3, the sensor data management unit 160 can execute at least one of the processes of displaying a warning on the user interface, recording the occurrence of the warning in a log, and performing notification based on the determination result.

[0103] 6.3 Function and Effect According to Embodiment 2, the deterioration status of each sensor channel can be grasped more accurately than in Embodiment 1.

[0104] 7. Embodiment 3 7.1 Configuration The configuration of Embodiment 3 may be the same as that of Embodiment 1 shown in FIG. 12.

[0105] 7.2 Operation The differences from Embodiment 1 will be described. In Embodiment 3, the target range is limited by using the fringe order MavEx, and the target range is grouped into a plurality of sections (groups) and counted for each group. The sensor data management unit 160 in Embodiment 3 operates as follows.

[0106] [Step 1C] The sensor data management unit 160 in Embodiment 3 makes the same determination as in Embodiment 1 by counting for each group. FIG. 27 is a graph showing an example of a fringe waveform detected on the line sensor 52 with 1024 channels. For example, as shown in FIG. 27, when selecting fringes with MavEx values between 0.5 and 1.5 in the left half range from the fringe center and calculating the central wavelength and spectral line width, the target range of MavEx for counting (target range) may only be 0.5 to 1.5.

[0107] At this time, for example, regarding the value of MavEx, the target range of MavEx is grouped for each range (section) of "0.1" such as 0.5 to 0.6, 0.6 to 0.7, ···, 1.3 to 1.4, 1.4 to 1.5, and counted for each group according to the MavEx value of the fringe. Each group grouped in the range of "0.1" is an example of the "fringe order group" in the present disclosure. The grouping section of the target range of MavEx may be other values than "0.1".

[0108] In the case of the example shown in FIG. 27, the MavEx of the fringe with MavEx between 0.5 and 1.5 is 1.21. In that case, as shown in FIG. 28, it is counted as "1" in the group of "1.2 to 1.3". If the MavEx of the fringe of the next pulse also falls within the range of "1.2 to 1.3", the count value of the MavEx group of "1.2 to 1.3" becomes "2".

[0109] When calculating the central wavelength from the fringe, not only one side such as the left half but also both the left and right fringes may be used for the calculation. Also, when calculating the spectral line width from the fringe, not the left side but the right fringe may be used for the calculation.

[0110] The count for each fringe order may be performed not for all pulses but for every certain number of pulses. For example, the count for each fringe order may be performed at a frequency of 1 pulse for every 10 pulses.

[0111] Also, the count for each fringe order may be performed not only for the fringe waveform obtained with 1 pulse, but also for the fringe waveform obtained by integrating a certain number of pulses. For example, the count for each fringe order may be performed for one fringe waveform obtained by integrating 10 pulses.

[0112] Also, the count for each fringe order may be performed for the fringe waveform after subtracting the average value of the background noise calculated in advance.

[0113] [Step 2C] The arithmetic unit 164 of the sensor data management unit 160 calculates the maximum value for the count value of each group of MavEx counted by the means in Step 1C every time. Alternatively, for the count value of each group, the maximum value, minimum value, and average value are calculated every time, and the difference between the maximum value and the minimum value, or the difference between the maximum value and the average value is calculated every time.

[0114] [Step 3C] The sensor data management unit 160 sets a threshold value Th4 for the maximum value of the count value obtained by the means in Step 2C, and determines that the line sensor is a sensor that cannot obtain an accurate fringe pattern when the value exceeds the threshold value Th4. The threshold value Th4 is an example of the "second threshold value" in the present disclosure.

[0115] FIG. 29 is a graph showing an example of the count value for each group when 50 billion pulses are reached. For example, when the threshold value Th4 of the count value is 50,000,000,000 (50 billion), as shown in FIG. 29, when the maximum value of the count value of each group of MavEx recorded in the sensor data management unit 160 exceeds 50 billion, it is determined that the line sensor 52 cannot obtain an accurate fringe pattern.

[0116] Regarding this threshold determination method, it may be performed on the difference between the maximum value and the minimum value, or the difference between the maximum value and the average value.

[0117] [Step 4C] When the value counted in Step 2C or the threshold Th4 causes an overflow, the counted value or the threshold Th4 may be used as a value divided by a certain numerical value. For example, the threshold Th4 may be a value obtained by dividing 50 billion by 1,000,000, that is, 50,000. Regarding the counted value recorded for each group of sensor channels of the line sensor 52 as well, the values divided by 1,000,000 are integrated in the same way, and the maximum value, or the difference between the maximum value and the minimum value, or the difference between the maximum value and the average value may be calculated to perform threshold determination.

[0118] [Step 5C] The count value of each group and the result of the threshold determination may be displayed by a user interface that monitors the operating status of the laser device 110.

[0119] [Step 6C] When the value used for threshold determination (in the case of Embodiment 3, the count value) exceeds the threshold Th4, the sensor data management unit 160 can execute at least one of the processes of displaying a warning on the user interface, recording the occurrence of the warning in a log, and performing notification based on the determination result.

[0120] The range of the MavEx value can be associated with the range of the sensor channel numbers, and the grouping by "0.1" for each value of MavEx can correspond to the grouping of the sensor channels. The count value of the MavEx value calculated for each group of MavEx is used as an index for quantitatively evaluating the local deterioration of the sensor channel range (group) corresponding to each group. This count value is an example of the "evaluation value" in the present disclosure.

[0121] 7.3 Function and Effect According to Embodiment 3, the degradation status of the line sensors 52 and 53 can be grasped more simply than in Embodiment 1 and Embodiment 2.

[0122] 8. Embodiment 4 8.1 Configuration The configuration of Embodiment 4 may be the same as that of Embodiment 1 shown in FIG. 12.

[0123] 8.2 Operation In Embodiment 4, the same determination as in Embodiment 1 or Embodiment 2 is made for the sensor channels corresponding to the range of MavEx in Embodiment 3.

[0124] For example, in the example shown in FIG. 30, the sensor channels in the range corresponding to MavEx of 0.5 to 1.5 in the left half range from the fringe center are the 130th to 300th.

[0125] Only for the sensor channels in this range, the integration of counts or the integration of light amounts as shown in Embodiment 1 or Embodiment 2 is performed, and the same threshold determination is made using their maximum value, or the difference between the maximum value and the minimum value, or the difference between the maximum value and the average value (see FIGS. 31 and 32).

[0126] The integration of counts or light amounts may be performed not for all pulses but for every certain number of pulses. The integration of counts or light amounts may be performed not only for the fringe waveform obtained from 1 pulse, but also for the fringe waveform obtained by integrating a certain number of pulses. The integration of counts or light amounts may be performed for the fringe waveform after subtracting the average value of the background noise calculated in advance.

[0127] FIG. 31 shows an example of the count value when 50 billion pulses are reached. FIG. 32 shows an example of the light amount integration value when 50 billion pulses are reached.

[0128] FIG. 33 is a flowchart showing an example of a process for determining the degradation status of the line sensor 52 by counting the number of times the fringe light amount exceeds the light amount threshold Th1 for each sensor channel.

[0129] In step S11, the sensor data management unit 160 sets the threshold Th2 to the light amount threshold Th1 of the fringe data, the maximum value of the count value, or the difference between the maximum value and the minimum value, or the difference between the maximum value and the average value.

[0130] In step S12, the line sensor 52 outputs the light amount data of the fringe pattern, and the sensor data management unit 160 acquires the light amount data output from the line sensor 52.

[0131] In step S13, the sensor data management unit 160 determines whether the fringe light amount exceeds the light amount threshold Th1 for each sensor channel.

[0132] In step S14, the sensor data management unit 160 counts "1" for the sensor channels where the fringe light amount exceeds the light amount threshold Th1 and "0" for the sensor channels that do not exceed it, and accumulates the values.

[0133] In step S15, the sensor data management unit 160 calculates the maximum value of the count values for each sensor channel. Alternatively, it calculates the maximum value, minimum value, and average value of the count values for each sensor channel, and calculates the difference between the maximum value and the minimum value, or the difference between the maximum value and the average value.

[0134] In step S16, the sensor data management unit 160 determines whether the maximum value of the count value, or the difference between the maximum value and the minimum value, or the difference between the maximum value and the average value exceeds the count value threshold Th2.

[0135] In step S17, when the count value threshold Th2 is exceeded, the sensor data management unit 160 determines that the fringe pattern cannot be accurately acquired.

[0136] FIG. 34 is a flowchart showing an example of a process for determining the deterioration status of the line sensor 52 by integrating the fringe light quantity values for each sensor channel.

[0137] In step S21, the sensor data management unit 160 sets the threshold value Th3 to the maximum value of the light quantity integration value of the fringe data, or the difference between the maximum value and the minimum value, or the difference between the maximum value and the average value.

[0138] In step S22, the line sensor 52 outputs the light quantity data of the fringe pattern, and the sensor data management unit 160 acquires the light quantity data output from the line sensor 52.

[0139] In step S24, the sensor data management unit 160 integrates the values of the fringe light quantity for each sensor channel.

[0140] In step S25, the sensor data management unit 160 calculates the maximum value of the light quantity integration values of each sensor channel. Alternatively, the maximum value, the minimum value, and the average value of the light quantity integration values of each sensor channel are calculated, and the difference between the maximum value and the minimum value, or the difference between the maximum value and the average value is calculated.

[0141] In step S26, the sensor data management unit 160 determines whether the maximum value of the light quantity integration value, or the difference between the maximum value and the minimum value, or the difference between the maximum value and the average value exceeds the threshold value Th3 for the light quantity integration.

[0142] In step S27, when the threshold value Th3 for the light quantity integration is exceeded, the sensor data management unit 160 determines that the fringe pattern cannot be accurately acquired.

[0143] 8.3 Operations and Effects According to Embodiment 4, the deterioration status of the line of the sensor can be grasped more simply than in Embodiment 1 or Embodiment 2. Further, according to Embodiment 4, the deterioration status of the line sensor can be grasped more accurately than in Embodiment 3.

[0144] 9. Embodiment 5 9.1 Configuration The configuration of Embodiment 5 may be the same as that of Embodiment 1 shown in FIG. 12.

[0145] 9.2 Operation In Embodiment 5, with regard to the calculation of the light quantity integration value in Embodiment 2, a process for correcting the deterioration amount depending on the ultraviolet irradiation energy integration amount is added. The line sensors 52 and 53 have different amounts of sensitivity degradation according to the ultraviolet irradiation energy integration amount (J / cm 2 ). FIG. 35 is a graph showing an example of sensor degradation characteristics indicating the relationship between the irradiation energy integration amount and the sensor sensitivity degradation. The horizontal axis represents the irradiation energy integration amount, and the vertical axis represents the sensor sensitivity (%). For example, as shown in FIG. 35, the amount of deterioration (sensitivity degradation amount) may become less sharp as the irradiation energy integration amount increases. Such characteristics depend on the structure and material of the sensor.

[0146] Therefore, in Embodiment 5, a look-up table (LUT) reflecting this sensor degradation characteristic is prepared in advance (see FIG. 36) so that the sensitivity conversion of the sensor can be performed from the irradiation energy integration amount.

[0147] FIG. 36 is a graph showing an example of LUT1 representing the relationship between the irradiation energy integration amount and the sensor sensitivity conversion amount. The horizontal axis represents the irradiation energy integration amount (J / cm 2 ), and the vertical axis represents the sensor sensitivity conversion factor (%). The LUT1 shown in FIG. 36 is a LUT reflecting the sensor degradation characteristics of FIG. 35. The sensor data management unit 160 stores a LUT1 as shown in FIG. 36, obtains the irradiation energy integration amount from the light quantity integration value for each sensor channel, and further estimates the amount of sensitivity degradation for each sensor channel using LUT1.

[0148] FIG. 37 is a graph in which the vertical axis of the graph in FIG. 26 is converted to the irradiation energy integration amount. For example, in the line sensor 52 with 448 channels of sensor channels shown in FIG. 26, the fringe light quantity integration value for each sensor channel is converted to the irradiation energy integration amount (J / cm 2) When converted to the scale of ( ), a graph as shown in FIG. 37 is obtained. By performing LUT conversion using the LUT1 shown in FIG. 36, sensitivity conversion values for each sensor channel as shown in FIG. 38 can be obtained. The LUT conversion applying LUT1 is an example of the "nonlinear conversion" in the present disclosure.

[0149] The vertical axis (FIG. 37) before LUT conversion is the approximate integrated irradiation energy amount (J / cm per sensor channel 2 ), and the vertical axis (FIG. 38) after LUT conversion is the sensitivity estimation value (%) for each sensor channel based on the sensor degradation characteristics.

[0150] In addition, in Embodiment 5, when converting the vertical axis of FIG. 26 to the scale of the integrated irradiation energy amount (J / cm 2 ), simply the light amount integrated value (Total Intensity) 4.0E+13 (a.u.) was set as the integrated irradiation energy amount 100 (kJ / cm 2 ). The notation "E+13" represents "10 to the 13th power".

[0151] The sensor degradation characteristics as shown in FIG. 35, or the LUT1 as shown in FIG. 36, can be obtained by irradiating the actual line sensor with light of uniform and constant energy (the wavelength is also the same as the target laser) and recording the channel average of the output values of the line sensor for each integrated irradiation energy amount.

[0152] In Embodiment 5, similar to other Embodiments 1 to 4, in the degradation determination of the sensor, the minimum value of the sensitivity estimation value, or the difference between the maximum value and the minimum value, or the difference between the minimum value and the average value may be calculated for threshold determination. The threshold used for the threshold determination in Embodiment 5 is an example of the "third threshold" in the present disclosure. The sensitivity estimation value calculated in Embodiment 5 is an evaluation index indicating that the more the value is small, the more the degradation of the sensor has progressed, and is an example of the "evaluation value" in the present disclosure.

[0153] 9.3 Actions and Effects According to Embodiment 5, since the amount of decrease in the sensitivity of the sensor can be estimated with higher accuracy, the accuracy of the degradation determination is further improved.

[0154] 10. Embodiment 6 10.1 Configuration The configuration of Embodiment 6 may be the same as that of Embodiment 1 shown in FIG. 12.

[0155] 10.2 Operation In Embodiment 6, with regard to the calculation of the estimated sensitivity in Embodiment 5, a process of correcting the deterioration amount depending on the integrated value of the irradiation energy of ultraviolet rays is added. Differences between Embodiment 6 and Embodiment 5 in terms of operation will be described.

[0156] In the description of Embodiment 5, the reason for assuming that the vertical axis of the graph in FIG. 37 is the approximate integrated irradiation energy (J / cm 2 ) for each sensor channel is that the data in FIG. 37 is actually not an accurate integration of the irradiation energy, but an integration of the signal values for each sensor channel output from the line sensor 52 during irradiation. Since the sensor deteriorates strictly each time it is irradiated and the output (sensitivity) gradually decreases, the actual integrated irradiation energy is larger for channels with larger light quantity integration values. Therefore, in order to further correct this effect, by performing conversion using the LUT2 as shown by the dashed line in FIG. 39 (see FIG. 40), the estimation accuracy of the deterioration amount of the sensor can be further improved.

[0157] The curve shown by the dashed line in FIG. 39 is an example of the LUT2 as a conversion table that corrects the decrease in sensor sensitivity due to the accumulation of light irradiation. The curve shown by the solid line is the LUT1 described in FIG. 36, which is a conversion table that does not correct the decrease in sensor sensitivity due to the accumulation of light irradiation.

[0158] FIG. 40 is a graph showing the estimated sensitivity for each sensor channel obtained by converting the data in FIG. 37 using the LUT2 in FIG. 39. By calculating the minimum value, or the difference between the maximum value and the minimum value, or the difference between the minimum value and the average value for the thus obtained estimated sensitivity, the deterioration status of the line sensor can be accurately determined.

[0159] 10.3 Effects According to Embodiment 6, the amount of decrease in the sensitivity of the sensor can be estimated with higher accuracy than in Embodiment 5, so that the accuracy of the deterioration determination is further improved.

[0160] 11. Other Examples of Laser Devices The laser oscillator including the chamber 20 shown in FIG. 12, the output coupling mirror 30, and the LNM 32 is an example of the "laser oscillator" in the present disclosure. In Embodiments 1 to 6, a narrow-band gas laser device was exemplified, but the laser oscillator is not limited to a gas laser device and may be a solid-state laser device including a semiconductor laser. Further, the laser device may be configured to include a laser amplifier.

[0161] 12. Regarding a Computer-Readable Medium Recording a Program As the sensor data management unit 160 described in each of the above embodiments, a program including instructions for causing a processor to function can be recorded on an optical disk, a magnetic disk, or other non-transitory computer-readable media (non-transitory information storage media in the form of physical objects), and the program can be provided through this computer-readable medium. Further, by incorporating the program recorded on the computer-readable medium into the computer and causing the processor to execute the instructions of the program, the function of the sensor data management unit 160 can be realized in the computer.

[0162] 13. Method for Manufacturing an Electronic Device FIG. 41 schematically shows a configuration example of the exposure apparatus 302. The method for manufacturing an electronic device is implemented by a system including a laser device 110 and an exposure apparatus 302. The pulsed laser light output from the laser device 110 is input to the exposure apparatus 302 and used as exposure light.

[0163] The exposure apparatus 302 includes an illumination optical system 304 and a projection optical system 306. The illumination optical system 304 illuminates a reticle pattern of a reticle (not shown) disposed on the reticle stage RT with the laser light incident from the laser apparatus 110. The projection optical system 306 reduces and projects the laser light that has passed through the reticle and forms an image on a workpiece (not shown) disposed on the workpiece table WT. The workpiece is a photosensitive substrate such as a semiconductor wafer coated with a photoresist.

[0164] The exposure apparatus 302 exposes the workpiece to the laser light reflecting the reticle pattern by synchronously translating the reticle stage RT and the workpiece table WT. After transferring the reticle pattern to the semiconductor wafer through the exposure process as described above, a semiconductor device can be manufactured through a plurality of processes. The semiconductor device is an example of an electronic device.

[0165] 14. Others In each of the above-described embodiments, an example of evaluating the degradation of the line sensors 52 and 53 used in the monitor module 40 has been described. However, the line sensors to be evaluated are not limited to this example, and may be line sensors applied to detectors other than the monitor module 40. The technology of the present disclosure is widely applicable as a technology for evaluating local degradation of a line sensor used for detecting interference fringes of pulsed laser light.

[0166] The above description is intended to be illustrative and not restrictive. Thus, it will be apparent to those skilled in the art that modifications can be made to the embodiments of the present disclosure without departing from the scope of the claims. It will also be apparent to those skilled in the art that the embodiments of the present disclosure can be used in combination.

[0167] The terms used throughout this specification and the claims should be construed as "non-limiting" terms unless otherwise specified. For example, terms such as "comprising", "having", "including", and "containing" should be construed as not excluding the presence of elements other than those described. Also, the modifier "one" should be construed to mean "at least one" or "one or more". Also, 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 to include combinations with things other than "A", "B", and "C".

Claims

1. Detecting interference fringes of pulsed laser light using a line sensor; Based on signal values obtained according to the light intensity of the interference fringes from each of a plurality of sensor channels included in at least a part of the sensor channel range of the line sensor, calculating an evaluation value serving as an indicator of deterioration for each sensor channel or for each group of sensor channels, and storing the evaluation value in a storage device; Determining the deterioration status of the line sensor based on the evaluation value; Obtaining at least one of a maximum value, a minimum value, and an average value of the evaluation value; A method for evaluating deterioration of a line sensor including the above.

2. A method for evaluating deterioration of a line sensor according to Claim 1, wherein the evaluation value is a count value obtained by counting the number of times the signal value obtained from the sensor channel exceeds a first threshold value. A method for evaluating deterioration of a line sensor.

3. A method for evaluating deterioration of a line sensor according to Claim 2, wherein the count value is a value obtained by dividing a value obtained by integrating the counted number of times by a first constant. A method for evaluating deterioration of a line sensor.

4. A method for evaluating deterioration of a line sensor according to Claim 1, wherein the evaluation value is a light quantity integrated value obtained by integrating the signal value or a value calculated by non-linearly transforming the light quantity integrated value. A method for evaluating deterioration of a line sensor.

5. A method for evaluating deterioration of a line sensor according to Claim 4, wherein the light quantity integrated value is obtained by dividing a value obtained by integrating the signal value by a second constant. A method for evaluating deterioration of a line sensor.

6. A method for evaluating deterioration of a line sensor according to Claim 4, wherein the light quantity integrated value is obtained by integrating a value obtained by subtracting a third constant from the signal value. A method for evaluating deterioration of a line sensor.

7. A method for evaluating deterioration of a line sensor according to Claim 4, wherein the non-linear transformation is a transformation that reflects sensor deterioration characteristics indicating the relationship between the integrated amount of irradiation energy of the pulsed laser light and the decrease in sensor sensitivity. A method for evaluating deterioration of a line sensor.

8. A method for evaluating deterioration of a line sensor according to Claim 1, wherein the determination of the deterioration status is performed by comparing the evaluation value with a second threshold value. A method for evaluating deterioration of a line sensor.

9. A method for evaluating deterioration of a line sensor according to Claim 1, wherein The evaluation value is an index indicating that the deterioration progresses as the value becomes smaller, The determination of the deterioration state is performed by comparing the minimum value of the evaluation value, or the difference between the maximum value and the minimum value, or the difference between the average value and the minimum value, with a third threshold value, A method for evaluating the deterioration of a line sensor.

10. A method for evaluating the deterioration of a line sensor according to claim 1, The processor performs a process of calculating the evaluation value from the data of the signal values for each sensor channel, a process of storing the evaluation value in the storage device, a process of determining the deterioration state of the line sensor based on the evaluation value and outputting a determination result, and executes A method for evaluating the deterioration of a line sensor.

11. A method for evaluating the deterioration of a line sensor according to claim 10, The process of outputting the determination result includes at least one of a process of causing the determination result to be displayed on a display device, a process of performing notification based on the determination result, and a process of recording the determination result in a log, A method for evaluating the deterioration of a line sensor.

12. Detecting interference fringes of pulsed laser light using a line sensor, Based on the signal values obtained according to the light intensity of the interference fringes from each of a plurality of sensor channels included in at least a part of the sensor channel range of the line sensor, for each sensor channel or for each group of sensor channels, calculating an evaluation value serving as an index of deterioration and storing the evaluation value in a storage device, Determining the deterioration state of the line sensor based on the evaluation value, Calculating the fringe order from the light intensity distribution of the interference fringes detected by the line sensor, and When the fringe order at the position of the distance r from the center of the concentric interference fringes is defined as MavEx, MavEx is obtained by setting the first inner radius of the interference fringes as r ｍ１ , the second inner radius as r ｍ２ and using the following formula MavEx = r ２ / (r ｍ２ ２ - r ｍ１ ２ ) is calculated by The evaluation value is a count value obtained by counting the values of the fringe order for each fringe order group obtained by dividing the range of the fringe order as the sensor channel range into a plurality of sections and grouping them, A method for evaluating the deterioration of a line sensor.

13. Detecting interference fringes of pulsed laser light using a line sensor, Based on the signal values obtained according to the light intensity of the interference fringes from each of a plurality of sensor channels included in at least a part of the sensor channel range of the line sensor, for each sensor channel or for each group of sensor channels, calculating an evaluation value serving as an index of deterioration and storing the evaluation value in a storage device, Determining the degradation status of the line sensor based on the evaluation value; Obtaining the maximum value of the evaluation value; and When the maximum value of the evaluation value exceeds a second threshold, the line sensor is determined to be a sensor that may not be able to detect accurate interference fringes; A method for evaluating the degradation of a line sensor.

14. Detecting interference fringes of pulsed laser light using a line sensor; Calculating an evaluation value serving as an indicator of degradation for each sensor channel or for each group of sensor channels based on signal values obtained from each of a plurality of sensor channels included in at least a part of the sensor channel range of the line sensor according to the light intensity of the interference fringes, and storing the evaluation value in a storage device; Determining the degradation status of the line sensor based on the evaluation value; Obtaining the maximum value and the minimum value of the evaluation value; and When the difference between the maximum value and the minimum value of the evaluation value exceeds a second threshold, the line sensor is determined to be a sensor that may not be able to detect accurate interference fringes; A method for evaluating the degradation of a line sensor.

15. Detecting interference fringes of pulsed laser light using a line sensor; Calculating an evaluation value serving as an indicator of degradation for each sensor channel or for each group of sensor channels based on signal values obtained from each of a plurality of sensor channels included in at least a part of the sensor channel range of the line sensor according to the light intensity of the interference fringes, and storing the evaluation value in a storage device; Determining the degradation status of the line sensor based on the evaluation value; Obtaining the maximum value and the average value of the evaluation value; and When the difference between the maximum value and the average value of the evaluation value exceeds a second threshold, the line sensor is determined to be a sensor that may not be able to detect accurate interference fringes; A method for evaluating the degradation of a line sensor.

16. An optical system that generates interference fringes when pulsed laser light is incident; A line sensor that detects the interference fringes; A processor that processes information obtained from the line sensor; And the processor is ​ Based on the signal values obtained according to the light intensity of the interference fringes from each of a plurality of sensor channels included in at least a part of the sensor channel range of the line sensor, an evaluation value serving as an index of deterioration is calculated for each sensor channel or for each group of sensor channels, and the evaluation value is stored in a storage device. Based on the evaluation value, the deterioration status of the line sensor is determined. At least one of the maximum value, minimum value, and average value of the evaluation value is obtained. Spectrum measurement device.

17. The spectrum measurement device according to claim 16, The optical system includes an etalon or a grating. Based on the information obtained from the line sensor, the processor measures at least one of the wavelength and spectral linewidth of the pulsed laser light. Spectrum measurement device.

18. The spectrum measurement device according to claim 16, and A laser oscillator that outputs the pulsed laser light. A laser device comprising the same.

19. A non-transitory computer-readable medium, To the processor, A process of acquiring a signal output from a line sensor that detects interference fringes of pulsed laser light, Based on the signal values obtained according to the light intensity of the interference fringes from each of a plurality of sensor channels included in at least a part of the sensor channel range of the line sensor, an evaluation value serving as an index of deterioration is calculated for each sensor channel or for each group of sensor channels, and the evaluation value is stored in a storage device. A process of determining the deterioration status of the line sensor based on the evaluation value, A process of obtaining at least one of the maximum value, minimum value, and average value of the evaluation value, A computer-readable medium recording a program for causing the above to be executed.

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