Sensor deterioration determination method

Abstract

A sensor deterioration determination method of one aspect of the present disclosure includes a determination step in which deterioration of at least one of a coarse sensor that receives interference fringes generated by a coarse spectrometer and a fine sensor that receives interference fringes generated by a fine spectrometer is determined, in the determination step, a plurality of lasers having different wavelengths are sequentially caused to be incident on the coarse spectrometer and the fine spectrometer, respectively, a coarse measurement wavelength for each wavelength is obtained from a plurality of the received interference fringes, a fine measurement wavelength for each wavelength is obtained from a plurality of the received interference fringes, a deterioration parameter for each wavelength is obtained from the coarse measurement wavelength for each wavelength and the fine measurement wavelength for each wavelength, and the deterioration parameter for each wavelength is compared with a threshold value.

Description

Technical Field

[0001] The present disclosure relates to a sensor degradation determination method. Background Art

[0002] In recent years, semiconductor exposure equipment has been required to improve resolution as semiconductor integrated circuits become increasingly miniaturized and highly integrated. Consequently, there has been a trend toward shorter wavelengths of light emitted from exposure light sources. For example, gas laser devices used for exposure include KrF excimer lasers, which output laser light with a wavelength of approximately 248 nm, and ArF excimer lasers, which output laser light with a wavelength of approximately 193 nm.

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

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent No. 4629910

[0007] Patent Document 2: Japanese Patent Application Laid-Open No. 1-173677

[0008] Patent Document 3: Japanese Patent Application Laid-Open No. 6-188502 Summary of the Invention

[0009] A sensor degradation determination method according to one aspect of the present disclosure includes the following steps: a determination step in which a processor determines degradation of at least one of a coarse sensor and a fine sensor, the coarse sensor receiving interference fringes generated by a coarse spectrometer and the fine sensor receiving interference fringes generated by a fine spectrometer having a higher resolution than the coarse spectrometer; and an output step in which the processor outputs a result of the determination. The determination step includes the following steps: a coarse measurement wavelength acquisition step in which a plurality of laser beams having different wavelengths are sequentially incident on the coarse spectrometer and a coarse measurement wavelength for each wavelength is acquired based on the plurality of interference fringes sequentially received by the coarse sensor; a fine measurement wavelength acquisition step in which a plurality of laser beams are sequentially incident on the fine spectrometer and a fine measurement wavelength for each wavelength is acquired based on the plurality of interference fringes sequentially received by the fine sensor; a degradation parameter acquisition step in which a degradation parameter for each wavelength is acquired based on the coarse measurement wavelength and the fine measurement wavelength for each wavelength; and a comparison step in which the degradation parameter for each wavelength is compared with a threshold value.

[0010] Another aspect of the present disclosure provides a method for determining sensor degradation, including the following steps: a determination step, in which a processor determines degradation of a sensor that receives interference fringes generated by a spectrometer; and an output step, in which the processor outputs a result of the determination, the determination step including the following steps: an intensity distribution acquisition step, in which a plurality of lasers having different wavelengths are sequentially incident on the spectrometer to acquire a plurality of intensity distributions corresponding to the plurality of interference fringes sequentially received by the sensor; a profile acquisition step, in which a profile of the maximum value of each pixel of the sensor is acquired based on the plurality of intensity distributions; a degradation parameter acquisition step, in which a degradation parameter of each pixel is acquired by normalizing the profile of the maximum value; and a comparison step, in which the degradation parameter of each pixel is compared with a threshold value.

[0011] Another aspect of the present disclosure provides a method for determining sensor degradation, including the following steps: a determination step, in which a processor determines the degradation of a sensor that receives interference fringes generated by a spectrometer; and an output step, in which the processor outputs a result of the determination, the determination step including the following steps: an intensity distribution acquisition step, in which a non-narrowband laser is incident on the spectrometer to obtain a first intensity distribution of the interference fringes received by the sensor; a degradation parameter acquisition step, in which the first intensity distribution is normalized using a reference intensity distribution to obtain a degradation parameter for each pixel of the sensor; and a comparison step, in which the degradation parameter of each pixel is compared with a threshold value. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Hereinafter, several embodiments of the present disclosure will be described as simple examples with reference to the accompanying drawings.

[0013] Figure 1 Schematic diagram showing the schematic structure of an etalon spectrometer.

[0014] Figure 2 FIG. 1 is a diagram showing the light intensity distribution of interference fringes detected by an image sensor.

[0015] Figure 3 1 is a diagram showing the structure of a narrowband laser device according to Comparative Example 1.

[0016] Figure 4 1 is a diagram showing the structure of a narrowband laser device according to Comparative Example 2.

[0017] Figure 5 1 is a flowchart illustrating the processing of the line sensor degradation determination method.

[0018] Figure 6 This is a diagram showing an example of an FC_diff overview.

[0019] Figure 7 This is a flowchart showing the process of a method for acquiring a sensitivity uniformity profile of a line sensor.

[0020] Figure 8 1 is a flowchart illustrating the processing of the line sensor degradation determination method using the U profile.

[0021] Figure 9 This is a diagram showing an example of a normalized U profile.

[0022] Figure 10 This is a diagram showing the structure of a narrowband laser device.

[0023] Figure 11 1 is a flowchart illustrating the processing of the line sensor degradation determination method.

[0024] Figure 12 This is a diagram showing an example of a free oscillation spectrum in a state without degradation.

[0025] Figure 13 This is a diagram showing an example of a free oscillation spectrum in a state where degradation occurs.

[0026] Figure 14 This is a diagram for explaining the prediction of the replacement timing of the monitor module.

[0027] Figure 15 is a diagram showing the structure of a laser system.

[0028] Figure 16 is a diagram showing the structure of a laser system.

[0029] Figure 17 It is a diagram schematically showing a configuration example of an exposure apparatus. DETAILED DESCRIPTION

[0030] -Table of contents-

[0031] 1. Description of terms / techniques

[0032] 1.1 Principle of the Etalon Spectrum Spectrum

[0033] 1.2 Calculation of measurement wavelength

[0034] 2. Overview of Narrowband Laser Device (Comparative Example 1)

[0035] 2.1 Structure of Narrowband Laser Device

[0036] 2.2 Action

[0037] 3. Overview of Narrowband Laser Device (Comparative Example 2)

[0038] 3.1 Structure of Narrowband Laser Device

[0039] 3.2 Action

[0040] 4.Topic

[0041] 5. Implementation Method 1

[0042] 5.1 Structure

[0043] 5.2 Action

[0044] 5.3 Action / Effect

[0045] 6. Implementation Method 2

[0046] 6.1 Structure

[0047] 6.2 Action

[0048] 6.3 Action / Effect

[0049] 7. Implementation Method 3

[0050] 7.1 Structure

[0051] 7.2 Action

[0052] 7.3 Action / Effect

[0053] 8. Implementation Method 4

[0054] 8.1 Structure

[0055] 8.2 Action

[0056] 8.3 Action / Effect

[0057] 9. Implementation Method 5

[0058] 9.1 Structure

[0059] 9.2 Action

[0060] 9.3 Action / Effect

[0061] 10. Method for manufacturing electronic devices

[0062] 11. Others

[0063] Below, embodiments of the present disclosure are described in detail with reference to the accompanying drawings. The embodiments described below illustrate several examples of the present disclosure and do not limit the content of the present disclosure. In addition, the structures and actions described in each embodiment are not necessarily all required structures and actions of the present disclosure. In addition, the same reference numerals are given to the same structural elements, and repeated descriptions are omitted.

[0064] 1. Description of terms / techniques

[0065] 1.1 Principle of the Etalon Spectrum Spectrum

[0066] Figure 1 Schematic diagram showing the schematic structure of the etalon spectrometer 10. Figure 1 As shown, the etalon beam splitter 10 has a diffusion element 12, a Fabry-Perot (FP) etalon 14, a condenser lens 16, and an image sensor 18. The image sensor 18 may be a photodiode array.

[0067] Laser light enters diffuser 12. Diffuser 12 scatters the incident laser light. This scattered light enters FP etalon 14. After passing through FP etalon 14, the laser light enters condenser lens 16. The laser light passes through condenser lens 16, generating interference fringes on the focal plane. Image sensor 18 is positioned at the focal plane of condenser lens 16, which has a focal length f. The transmitted light, focused by condenser lens 16, generates interference fringes on image sensor 18. Image sensor 18 detects the generated interference fringes.

[0068] 1.2 Calculation of measurement wavelength

[0069] Generally speaking, the interference fringes of an etalon are expressed by the following formula (1).

[0070] [Mathematical formula 1]

[0071]

[0072] Here, λ is the wavelength of the laser, n is the refractive index of the air gap, d is the distance between the mirrors, m is an integer, θ is the incident angle of the laser, and r m is the radius of the interference fringes.

[0073] As shown in formula (1), the radius r of the interference fringe is mThe square of is proportional to the wavelength λ of the laser. Therefore, the spectral line width (spectral profile) and central wavelength of the entire laser can be detected based on the detected interference fringes. The spectral line width and central wavelength can be obtained from the detected interference fringes by an information processing device (not shown), or by a wavelength control unit (e.g. Figure 3 The wavelength control unit 60) is used for calculation.

[0074] Figure 2 The figure shows the light intensity distribution of the interference fringes detected by the image 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 fringes m The square of the interference fringe can also be calculated from the average of the square of the inner radius r1 and the square of the outer radius r2 at the half-value position of the interference fringe. m The square of can also be calculated according to the following formula (2).

[0075] r m 2 =(r1 2 +r2 2 ) / 2…(2)

[0076] 2. Overview of Narrowband Laser Device (Comparative Example 1)

[0077] 2.1 Structure of Narrowband Laser Device

[0078] The comparative examples disclosed herein are methods that the applicant has recognized as being known only to the applicant, and are not publicly known examples acknowledged by the applicant himself. Figure 3 1 is a diagram showing the structure of the narrowband laser device 1 of Comparative Example 1. Figure 3 As shown, the narrowband laser device 1 includes a cavity 20 , a power supply 26 , an output coupling mirror 30 , a narrowband module 32 , a monitor module (MM) 40 , a wavelength control unit 60 , a laser control unit 61 , and a driver 62 .

[0079] The output coupling mirror 30 and the narrowband module 32 constitute a laser resonator. The cavity 20 is arranged on the optical path of the laser resonator. The narrowband module 32 includes a plurality of (eg, two) prisms 34, a grating 36, and a rotating stage 38.

[0080] The prism 34 is configured to function as a beam expander. The grating 36 is arranged in a Littrow configuration so that the incident angle and the diffraction angle coincide. The prism 34 is placed above a rotating stage 38 and is configured so that the angle of incidence with respect to the grating 36 changes as the prism 34 is rotated by the rotating stage 38.

[0081] The cavity 20 includes windows 22a and 22b and a pair of electrodes 24a and 24b. The cavity 20 contains laser gas. 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.

[0082] Electrodes 24a and 24b (an example of a pair of discharge electrodes) are arranged in the chamber 20 and are connected to the chamber 20. Figure 3 The electrodes are arranged to face each other in a direction perpendicular to the paper (direction V), and are arranged so that the longitudinal direction of the electrodes aligns with the optical path of the laser resonator. They are connected to a power supply 26. Windows 22a and 22b (an example of a first window and a second window) perform discharge excitation between the discharge electrodes and are arranged so that the amplified laser light passes through these windows 22a and 22b.

[0083] The power supply 26 includes a switch 28 and is connected so that a high voltage is applied between the electrodes 24 a and 24 b in the chamber 20 when the switch 28 is turned on.

[0084] The output coupling mirror 30 is coated with a film that reflects part of the laser light and transmits part of it.

[0085] 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 .

[0086] Beam splitter 41 is arranged on the optical path of the laser light output from output coupling mirror 30 so that the laser light reflected by beam splitter 41 enters beam splitter 42. The laser light transmitted through beam splitter 41 is emitted from narrowband laser device 1. Exposure device 302 is arranged so that the laser light emitted from narrowband laser device 1 enters exposure device 302.

[0087] The beam splitter 42 is arranged so that the laser light reflected by the beam splitter 41 is incident on the optical path of the laser light reflected by the beam splitter 42 and enters the pulse energy monitor 44. The pulse energy monitor 44 may be a photodiode, a phototube, or a pyroelectric element.

[0088] The condenser lens 43 is arranged so that the laser light transmitted through the beam splitter 42 enters the condenser lens 43 .

[0089] The sealed chamber 45 contains a diffuser plate 46 , a fine etalon 47 , a coarse etalon 48 , a beam splitter 49 , a condenser lens 50 , and a condenser lens 51 .

[0090] The diffuser plate 46 is disposed near the focusing position of the condenser lens 43. The diffuser plate 46 is an optical element made of synthetic quartz with one surface processed to be flat and the other surface processed to be frosted. The diffuser plate 46 is sealed in the sealing chamber 45 by an O-ring (not shown).

[0091] Fine etalon 47 (an example of a fine beam splitter) is arranged so that laser light, after passing through diffuser plate 46, passes through beam splitter 49 and enters fine etalon 47. Beam splitter 49 is arranged so that laser light, after being partially reflected by beam splitter 49 on the optical path between diffuser plate 46 and fine etalon 47, enters coarse etalon 48 (an example of a coarse beam splitter). Fine etalon 47 and coarse etalon 48 are air-gap etalons formed by two mirrors (not shown) coated with a partial reflection film, optically contacting each other via a spacer (not shown).

[0092] 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 (3).

[0093] FSR <FSRc…(3)

[0094] The free spectrum range FSR is expressed by the following formula (4).

[0095] FSR=λ 2 / (2nd)…(4)

[0096] FSRf and FSRc are FSRf = 10 pm and FSRc = 400 pm, respectively. In the case of KrF excimer laser, FSRc can be 500 pm, and in the case of ArF excimer laser, FSRc can be 300 pm. Thus, the resolution of the fine etalon 47 is higher than that of the coarse etalon 48.

[0097] Condensing lens 50 is disposed on the optical path of the laser beam after passing through fine etalon 47 and is sealed in sealing chamber 45 via an O-ring (not shown). Condensing lens 51 is disposed on the optical path of the laser beam after passing through coarse etalon 48 and is sealed in sealing chamber 45 via an O-ring (not shown). The focal length of condensing lens 51 is shorter than that of condensing lens 50.

[0098] Line sensor 52 (an example of a fine sensor) and line sensor 53 (an example of a coarse sensor) are respectively arranged on the focal planes of condenser lens 50 and condenser lens 51. Line sensor 52 and line sensor 53 are photodiode arrays composed of a one-dimensional array of multiple light-receiving elements (pixels), and each outputs the intensity distribution of the received interference fringes.

[0099] The interference fringes of the etalon are expressed using equations (1) to (5).

[0100] mλ=2nd·cosθ…(5)

[0101] The wavelength control unit 60 is configured to communicate with the line sensor 52, the line sensor 53, the laser control unit 61, and the driver 62. The laser control unit 61 is an example of a processor. The processor of 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 specifically configured or programmed to perform the various processes included in the present disclosure. The laser control unit 61 is configured to communicate 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 configured to communicate with the rotary table 38.

[0102] 2.2 Action

[0103] The laser control unit 61 reads data on the target pulse energy Et and target wavelength λt from the exposure device control unit 310. The laser control unit 61 sends a charging voltage V to the power supply 26 and sends the target wavelength λt to the wavelength control unit 60, so that the pulse energy of the pulsed laser reaches the target pulse energy Et and the oscillation wavelength reaches the target wavelength λt. The laser control unit 61 turns on the switch 28 in response to the oscillation trigger sent from the exposure device control unit 310.

[0104] When switch 28 is turned on, a high voltage is applied between electrodes 24a and 24b, causing discharge and exciting the laser gas. When the laser gas is excited, it oscillates in the laser resonator formed by the narrowband module 32 and the output coupling mirror 30, and the narrowband pulsed laser light is output from the output coupling mirror 30.

[0105] The pulse laser light output from the output coupling mirror 30 and sampled by the beam splitter 41 enters the beam splitter 42. The reflected light and the transmitted light of the beam splitter 42 enter the pulse energy monitor 44 and the diffuser 46 of the sealed chamber 45, respectively.

[0106] The laser control unit 61 controls the charging voltage V of the power supply 26 based on the detection result of the pulse energy monitor 44 so that the pulse energy of the pulse laser light becomes the target pulse energy Et.

[0107] Meanwhile, the wavelength control unit 60 measures the intensity distribution of each interference fringe generated by the coarse etalon 48 and the fine etalon 47 for each pulse using the line sensors 53 and 52, and reads the data. Based on the interference fringe intensity distribution data read for each pulse, the wavelength control unit 60 calculates the measured wavelength λ of the pulsed laser light for each pulse. The measured wavelength λ can also be calculated based on data accumulated and averaged over multiple pulses, rather than for each pulse. Based on the calculated measured wavelength λ, the wavelength control unit 60 controls the rotating stage 38 of the prism 34 via the driver 62 so that the oscillation wavelength of the pulsed laser light reaches the target wavelength λt.

[0108] As described above, the pulse energy and oscillation wavelength of narrowband laser device 1 are stabilized at the target pulse energy Et and target wavelength λt provided by exposure device 302. Here, sealed chamber 45 is sealed, so the difference in refractive index n of the air gaps in equation (4) between coarse etalon 48 and fine etalon 47 is minimized, thereby reducing wavelength measurement errors caused by drift of coarse etalon 48 and fine etalon 47.

[0109] Generally speaking, when the finesse of the etalon is F, the resolution R is expressed as R = FSR / F. When the finesse is approximately the same, the resolution R increases as the FSR decreases. However, when the FSR decreases, the interference fringes appear approximately the same when the wavelength changes by the amount of the FSR, making them indistinguishable when measured using a single etalon with a smaller FSR. According to the narrowband laser device 1, when the wavelength is changed by approximately 400 pm and the wavelength is detected 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, thereby enabling high-precision wavelength measurement.

[0110] 3. Overview of Narrowband Laser Device (Comparative Example 2)

[0111] 3.1 Structure of Narrowband Laser Device

[0112] Figure 4 : is a diagram showing the structure of a narrowband laser device 2 of Comparative Example 2. The narrowband laser device 2 has a grating spectrometer instead of the coarse etalon 48 of the narrowband laser device 1. Figure 4 As shown, the narrowband laser device 2 includes a beam splitter 70 , an aperture 71 , a mirror 72 , a collimating lens 73 , and a roughing grating 74 .

[0113] The beam splitter 70 is disposed on the optical path of the laser beam after passing through the condenser lens 43 . The aperture 71 is disposed near the condensing position of the condenser lens 43 so that the laser beam reflected by the beam splitter 70 enters the aperture 71 .

[0114] The mirror 72 is arranged so that the laser beam passing through the hole 71 enters the mirror 72. The collimator lens 73 is arranged so that the laser beam reflected by the mirror 72 enters the collimator lens 73. The roughing grating 74 is arranged so that the laser beam entering from the collimator lens 73 is reflected toward the collimator lens 73.

[0115] The line sensor 53 is arranged so that the laser light reflected by the rough grating 74 and passed through the collimator lens 73 enters the line sensor 53 .

[0116] 3.2 Action

[0117] The pulse laser light output from the output coupling mirror 30 and sampled by the beam splitter 41 enters the beam splitter 42 . The light transmitted through the beam splitter 42 passes through the condenser lens 43 and enters the beam splitter 70 .

[0118] The reflected light and the transmitted light of the beam splitter 70 are incident on the hole 71 and the diffusion plate 46 of the sealed cavity 45 , respectively.

[0119] The pulsed laser light passing through the aperture 71 is reflected by the mirror 72, collimated by the collimator lens 73, and incident on the roughing grating 74. The pulsed laser light diffracted by the roughing grating 74 passes through the collimator lens 73, and generates interference fringes on the line sensor 53.

[0120] As described above, the narrowband laser device 2 can measure a wavelength range corresponding to the free spectrum range FSRc of the coarse etalon 48 using a grating spectrometer. Therefore, similar to the narrowband laser device 1, the line sensors 53 and 52 perform measurements for each pulse, thereby enabling highly accurate measurement of a wide wavelength range through coordinated efforts.

[0121] 4.Topic

[0122] The line sensors 52 and 53 of the monitor module 40 degrade with use. Conventionally, this degradation was anticipated, and monitor modules 40 used beyond a predetermined number of shots (SL) were replaced. However, it is known that many monitor modules exist where, depending on the usage of the monitor module 40 and the individual differences between the line sensors 52 and 53, linear errors remain within an acceptable range, allowing full use, even when used beyond the SL.

[0123] Therefore, it is economically preferable to evaluate the degradation of the uniformity of the sensitivity of the line sensors 52 and 53 or the measurement linearity error on-site at a semiconductor manufacturing plant or the like and replace only the problematic monitor module 40. Therefore, a countermeasure is desired that evaluates the degradation state of each of the line sensors 52 and 53 and determines whether replacement is necessary.

[0124] 5. Implementation Method 1

[0125] 5.1 Structure

[0126] The hardware configuration of the first embodiment is the same as that of the narrowband laser device 1. The difference is that the laser control unit 61 also performs processing of the line sensor degradation determination method.

[0127] 5.2 Action

[0128] Figure 5 1 is a flowchart showing the processing of the line sensor degradation determination method. Here, an example of determining degradation of at least one of the line sensor 52 and the line sensor 53 will be described.

[0129] In step S1, the laser control unit 61 sets the oscillation pulse energy PE to 10 mJ. In the following disclosure, 10 mJ is an example, and any value other than 10 mJ may be set as long as it is a fixed value.

[0130] In step S2, the laser control unit 61 initializes various parameters. Here, the laser control unit 61 sets the determination result flag to false, sets the threshold TH to 3.20 pm, sets the initial oscillation wavelength WL0 to 193,310.00 pm, sets the wavelength interval ΔWL to 10.00 pm, sets the final oscillation wavelength WLE to 193,420.00 pm, sets the arrays WLc[1] to WLc

[11] to 0, and sets the arrays WLf[1] to WLf

[11] to 0.

[0131] In step S3 , the laser control unit 61 sets the oscillation wavelength WL to the initial oscillation wavelength WL0 and initializes the index i indicating the order of the oscillation wavelength WL to 0.

[0132] In step S4 , the laser control unit 61 adds the wavelength interval ΔWL to the oscillation wavelength WL, and adds 1 to the index i to update the index i.

[0133] In step S5, the laser control unit 61 sets the target wavelength λt to the oscillation wavelength WL and performs laser oscillation at the oscillation pulse energy PE. As a result, pulsed laser light having the oscillation wavelength WL and the oscillation pulse energy PE is incident on the sealed cavity 45 through the diffuser 46. The pulsed laser light incident on the sealed cavity 45 is split by the beam splitter 49 into laser light incident on the fine etalon 47 and laser light incident on the coarse etalon (an example of a branching step), and then incident on the fine etalon 47 and the coarse etalon 48.

[0134] In step S6, the laser control unit 61 obtains the fine measurement wavelength calculated by the wavelength control unit 60 based on the intensity distribution of the interference fringes received by the line sensor 52, and substitutes the obtained fine measurement wavelength into the array WLf[i] (an example of the fine measurement wavelength acquisition step). In addition, the laser control unit 61 obtains the coarse measurement wavelength calculated by the wavelength control unit 60 based on the intensity distribution of the interference fringes received by the line sensor 53, and substitutes the obtained coarse measurement wavelength into the array WLc[i] (an example of the coarse measurement wavelength acquisition step).

[0135] In step S7, the laser control unit 61 calculates the difference between the coarse measurement wavelength and the fine measurement wavelength (measurement wavelength error), that is, FC_diff (an example of a degradation parameter) (an example of the degradation parameter acquisition step). Here, the value of WLc[i] - WLf[i] is substituted into the array FC_diff[i].

[0136] In step S8, the laser control unit 61 compares the absolute value of the value of FC_diff[i], that is, ABS|FC_diff[i]|, with the threshold TH (an example of the comparison step), and determines whether the threshold TH is greater than ABS|FC_diff[i]| (an example of the determination step). When ABS|FC_diff[i]| < TH is not satisfied, the laser control unit 61 performs the process of step S10 after performing the process of step S9. When ABS|FC_diff[i]| < TH is satisfied, the laser control unit 61 performs the process of step S10.

[0137] In step S9, the laser control unit 61 makes the determination result flag true (an example of the output step).

[0138] In step S10, the laser control unit 61 determines whether the oscillation wavelength WL is the final oscillation wavelength WLE. When WL = WLE is not satisfied, the laser control unit 61 performs the process of step S4. When WL = WLE is satisfied, the laser control unit 61 ends the processing of this flowchart.

[0139] By repeatedly performing the process of step S4, the oscillation wavelength WL is updated at intervals of 10.00 pm from 193,320.00 pm to 193,420.00 pm, and the index i is updated one by one from 1 to 10. The difference between the shortest wavelength and the longest wavelength among the updated oscillation wavelengths WL is smaller than the FSRc of the coarse etalon 48. That is, each oscillation wavelength is within the range of the FSRc of the coarse etalon 48 and differs from each other by the FSRf of the fine etalon 47. In addition, the wavelength interval ΔWL is not limited to the FSRf of the fine etalon 47, and may also be a wavelength interval smaller than the FSRf.<{

[0140] By repeatedly performing the process of step S5, a plurality of lasers with different oscillation wavelengths WL are sequentially incident on the fine etalon 47 and the coarse etalon 48. By repeatedly performing the process of step S6, the coarse measurement wavelength and the fine measurement wavelength for each oscillation wavelength WL (an example of each wavelength) are obtained. By repeatedly performing the process of step S7, the FC_diff for each oscillation wavelength WL is calculated.

[0141] When repeatedly performing the process of step S8 and not satisfying |FC_diff[i]| < TH even once, in step S9, the determination result flag becomes true. That is, when at least one of the deterioration parameters is above the threshold TH, the laser control unit 61 determines that at least one of the line sensors 52 and 53 has deteriorated, and outputs a signal prompting replacement of the monitor module 40. The laser control unit 61 may also end the processing of this flowchart after performing the process of step S9.

[0142] Figure 6 is a diagram showing an example of the FC_diff profile obtained by plotting FC_diff against wavelength. Figure 6 The horizontal axis of is wavelength, with the unit being nm, showing the digits after the decimal point of 193 nm. In addition, Figure 6 the vertical axis of is the measurement wavelength error FC_diff, with the unit being pm. In Figure 6 , the FC_diff profile in the case of deterioration is represented by triangular plotting points, and the FC_diff profile in the case of no deterioration is represented by quadrilateral plotting points. In addition, Figure 6 the UL (Upper Limit) and LL (Lower Limit) of show the threshold TH above and below, respectively, with FC_diff = 0 as the reference.

[0143] As Figure 6 shown, regarding the FC_diff profile in the case of no deterioration, within the wavelength range of 100.00 pm from 193,320.00 pm to 193,420.00 pm, any measurement wavelength error is 0 pm. In addition, the measurement wavelength error in the FC_diff profile in the case of deterioration varies by about -1.0 pm according to the wavelength.

[0144] Figure 6 The FC_diff profile in the case of deterioration in is between UL and LL, so it can be determined that there is no deterioration. Even if the absolute value of the measurement wavelength error is large, it is about 1.0 pm, which is smaller than the threshold TH of 3.20 pm. Therefore, in the Figure 5 [[ID= Figure 6 The curve graph allows users to understand the degradation status.

[0145] You can also follow Figure 5 The line sensor degradation determination method shown determines degradation of at least one of the line sensor 52 and the line sensor 53 of the narrowband laser device 2 .

[0146] In this embodiment, the measurement wavelength error FC_diff is set as the difference between the coarse measurement wavelength and the fine measurement wavelength. However, as long as the difference between the coarse measurement wavelength and the fine measurement wavelength can be known, the measurement wavelength error FC_diff may be the ratio of the coarse measurement wavelength to the fine measurement wavelength, or the square difference between the coarse measurement wavelength and the fine measurement wavelength. Figure 6 In this manner, the order of the fine etalon can be determined using the coarse-precision measurement wavelength obtained from the coarse etalon, thereby improving the measurement accuracy of the fine measurement wavelength.

[0147] As threshold TH, a warning threshold TH1 and an error threshold TH2 may be set. In this case, as a result of the line sensor degradation determination method, a signal indicating that the monitor module 40 is about to be replaced may be output when the absolute value of the measured wavelength error exceeds threshold TH1. Furthermore, a signal urging replacement of the monitor module 40 may be output when the absolute value of the measured wavelength error exceeds threshold TH2. In this case, threshold TH1 and threshold TH2 may be set such that threshold TH1 < threshold TH2.

[0148] When the laser control unit 61 is connected to a rewritable non-transitory storage medium (not shown), the storage medium stores a program for causing a computer to execute each process of the line sensor degradation determination method. The storage medium may also be stored via a communication line such as the Internet.

[0149] 5.3 Action / Effect

[0150] According to the first embodiment, even in narrowed-band laser devices 1 and 2 already installed on-site, it is possible to determine whether at least one of line sensor 52 and line sensor 53 has deteriorated. Therefore, the degradation status of line sensor 52 and line sensor 53 can be determined at low cost.

[0151] According to the first embodiment, the wavelength is changed within the FSRc range of the coarse etalon 48. This makes it easier to maintain constant pulse energy, and thus, relatively high measurement accuracy can be expected. Furthermore, by changing the wavelength without exceeding the FSRc, there is no risk of missing the order of interference fringes generated by the coarse etalon 48.

[0152] Here, the change interval of the oscillation wavelength W is made the same as the FSRf of the fine etalon 47. Therefore, the position of the interference fringes generated by the fine etalon 47 always corresponds to the position of the same pixel of the line sensor 52. Therefore, the output of the line sensor 53 can be evaluated while the output of the line sensor 52 is kept constant. Therefore, the FC_diff profile mainly indicates the amount of measurement linearity degradation of the line sensor 53.

[0153] 6. Implementation Method 2

[0154] 6.1 Structure

[0155] The hardware configuration of the second embodiment is the same as that of the narrowband laser device 1. The laser control unit 61 also performs processing of the line sensor degradation determination method. Here, it is assumed that the number of pixels of the line sensor 52 is 512 pixels.

[0156] 6.2 Action

[0157] An example of determining degradation of the line sensor 52 will be described. The line sensor degradation determination method of the second embodiment uses a sensitivity uniformity profile (U profile) of the line sensor 52 . Figure 7 This is a flowchart showing the processing of a method for acquiring a U profile by the line sensor 52 .

[0158] In step S11 , the laser control unit 61 sets the oscillation pulse energy PE to 10 mJ.

[0159] In step S12, the laser control unit 61 initializes various parameters. Here, the laser control unit 61 sets the initial oscillation wavelength WL0 to 193,360.00 pm, the wavelength interval ΔWL to 0.01 pm, the free spectrum range FSR corresponding to the amplitude to 10.00 pm, the same as the FSRf of the fine etalon 47, the margin α to 1.00 pm, the arrays Uprofile[1] to Uprofile

[512] to 0, and the arrays Pix[1] to Pix

[512] to 0.

[0160] In step S13, the laser control unit 61 calculates the final oscillation wavelength WLE. The final oscillation wavelength WLE can be expressed as WLE=WL0+FSR+α. Here, the final oscillation wavelength WLE is 193,371.00 pm.

[0161] In step S14 , the laser control unit 61 sets the oscillation wavelength WL to the initial oscillation wavelength WL0 .

[0162] In step S15 , the laser control unit 61 updates the oscillation wavelength WL by adding the wavelength interval ΔWL.

[0163] In step S16 , the laser control unit 61 sets the target wavelength λt to the oscillation wavelength WL and performs laser oscillation at the oscillation pulse energy PE. As a result, the pulsed laser light of the oscillation wavelength WL and the oscillation pulse energy PE is incident on the fine etalon 47 .

[0164] In step S17, the laser control unit 61 substitutes the measured value of each pixel of the line sensor 53 into the array Pix[1] to Pix

[512] to obtain the intensity distribution corresponding to the interference fringes (an example of the intensity distribution acquisition step). In addition, the laser control unit 61 initializes the index i representing the pixel position of the line sensor 53 to 1.

[0165] In step S18, the laser control unit 61 determines whether the value of the array Pix[i] is greater than the value of the array Uprofile[i]. If Pix[i]>Uprofile[i], the laser control unit 61 performs the process of step S19 and then proceeds to step S20. If Pix[i]>Uprofile[i] is not satisfied, the laser control unit 61 proceeds to step S20.

[0166] In step S19 , the laser control unit 61 substitutes the value of the array Pix[i] into the array Uprofile[i] (an example of a profile acquisition step).

[0167] In step S20 , the laser control unit 61 adds 1 to the index i to update it.

[0168] In step S21, the laser control unit 61 determines whether the index i is 512. If i=512 is not satisfied, the laser control unit 61 performs the process of step S18. If i=512 is satisfied, the laser control unit 61 performs the process of step S22.

[0169] In step S22, the laser control unit 61 determines whether the oscillation wavelength WL is the final oscillation wavelength WLE. If WL=WLE is not satisfied, the laser control unit 61 performs the process of step S15. If WL=WLE is satisfied, the laser control unit 61 ends the process of this flowchart.

[0170] By repeatedly executing the process of step S15 , the oscillation wavelength WL is updated from 193,360.01 pm to 193,371.00 pm at intervals of 0.01 pm. The difference between the shortest wavelength and the longest wavelength in the updated oscillation wavelength WL is larger than the FSRf of the fine etalon 47 .

[0171] By repeatedly performing the process of step S16 , a plurality of laser beams having different oscillation wavelengths WL are sequentially incident on the fine etalon 47 .

[0172] By repeatedly executing the process of step S17 , the laser control unit 61 obtains a plurality of intensity distributions corresponding to a plurality of interference fringes corresponding to a plurality of laser beams having different oscillation wavelengths WL incident sequentially and received sequentially by the line sensor 52 .

[0173] By repeatedly performing the processing of steps S18 and S19, a profile of the maximum value for each pixel of line sensor 52 (an example of a profile for each pixel) is obtained based on the multiple intensity distributions. In other words, the array Uprofile[1] to Uprofile

[512] finally obtained becomes the U profile representing the maximum value for each pixel of line sensor 53.

[0174] Figure 8 1 is a flowchart illustrating the processing of the line sensor degradation determination method using the U profile.

[0175] In step S31, the laser control unit 61 Figure 7 The method for obtaining the U profile of the line sensor 52 shown obtains Uprofile[1] to Uprofile

[512] .

[0176] In step S32, the laser control unit 61 initializes various parameters. Here, the laser control unit 61 sets the determination result flag to false, the threshold value TH to 0.90, the total SUM to 0, the average value AVE to 0.0, and the arrays N_Uprofile[1] to N_Uprofile

[512] to 0.0.

[0177] In step S33 , the laser control unit 61 initializes the index i to 1.

[0178] In step S34 , the laser control unit 61 adds Uprofile[i] to the total SUM.

[0179] In step S35 , the laser control unit 61 adds 1 to the index i to update it.

[0180] In step S36, the laser control unit 61 determines whether the index i is 512. If i=512 is not satisfied, the laser control unit 61 performs the process of step S34. If i=512 is satisfied, the laser control unit 61 performs the process of step S37.

[0181] The process of step S34 is repeatedly performed until the index i reaches 512, whereby the total SUM becomes the total of the values ​​of the arrays Uprofile[1] to Uprofile

[512] .

[0182] In step S37, the laser control unit 61 calculates the average value AVE of the values of the arrays Uprofile[1] to Uprofile

[512] by AVE = SUM / 512.

[0183] In step S38, the laser control unit 61 initializes the index i to 1.

[0184] In step S39, the laser control unit 61 calculates a normalized U profile (an example of a deterioration parameter acquisition step) obtained by normalizing the value of the array Uprofile[i] using the average value AVE. Here, the value of Uprofile[i] / AVE is substituted into the array N_Uprofile[i].

[0185] In step S40, the laser control unit 61 compares the value of the array N_Uprofile[i] (an example of a deterioration parameter) with the threshold TH (an example of a comparison step), and determines whether the threshold TH is greater than the value of the array N_Uprofile[i] (an example of a determination step). When N_Uprofile[i]<TH is satisfied, the laser control unit 61 performs the process of step S42 after performing the process of step S41. When N_Uprofile[i]<TH is not satisfied, the laser control unit � performs the process of step S42.

[0186] In step S41, the laser control unit 61 makes the determination result flag true (an example of an output step).

[0187] In step S42, the laser control unit 61 updates the index i by adding 1.

[0188] In step S43, the laser control unit 61 determines whether the index i is 513. When i = 513 is not satisfied, the laser control unit 61 performs the process of step S39. When i = 513 is satisfied, the laser control unit 61 ends the process of this flowchart.

[0189] [[ID=,1]]When the processes of step S39 and step S40 are repeatedly performed and N_Uprofile[i]<TH is satisfied at least once, in step S41, the determination result flag becomes true. That is, when at least one of the deterioration parameters is less than the threshold TH, the laser control unit 61 determines that the line sensor 52 is deteriorated and outputs a signal prompting replacement of the monitor module 40.

[0190] Figure 9 It is a diagram showing an example of a normalized U profile. The horizontal axis represents the pixel position of the line sensor 52, and the vertical axis represents the deterioration rate (unit: %). Figure 9F9A shows a normalized U profile without degradation, and F9B shows a normalized U profile with degradation. As shown in F9A, in the normalized U profile without degradation, the degradation rate of all pixels in line sensor 52 is approximately 0%. Furthermore, in the normalized U profile with degradation, some pixels have a degradation rate exceeding -5%.

[0191] The degradation limit standard may also be -5% (threshold TH is 0.95).

[0192] While the example described here involves determining degradation of line sensor 52 of narrowband laser device 1, degradation of line sensor 53 can also be determined. When determining degradation of line sensor 53, the free spectrum range (FSR) corresponding to the amplitude is set equal to the FSRc of coarse etalon 48. Furthermore, when determining degradation of line sensor 53, the degradation limit criterion can be -20% (threshold value TH is 0.80). Furthermore, degradation of at least one of line sensor 52 and line sensor 53 of narrowband laser device 2 can also be determined.

[0193] 6.3 Action / Effect

[0194] According to the second embodiment, even for narrowed-band laser devices 1 and 2 already installed on site, degradation of at least one of line sensor 52 and line sensor 53 can be determined. Therefore, the degradation status of line sensor 52 and line sensor 53 can be determined individually.

[0195] According to the second embodiment, by using the normalized U profile obtained by normalizing the U profile using the average value AVE, it is possible to quantitatively evaluate the sensitivity degradation of each pixel individually for both the line sensor 52 and the line sensor 53 .

[0196] 7. Implementation Method 3

[0197] 7.1 Structure

[0198] Figure 10 1 is a diagram showing the configuration of the narrowband laser device 3 . The narrowband laser device 3 includes a total reflection mirror 80 .

[0199] The total reflection mirror 80 has an advancing and retracting mechanism (not shown) that allows the total reflection mirror 80 to be inserted between the cavity 20 and the bandwidth narrowing module 32 (an example of a bandwidth narrowing optical system) or to be retracted from between the cavity 20 and the bandwidth narrowing module 32 .

[0200] Alternatively, a replacement mechanism and an alignment mechanism may be provided in the narrowband laser device 3 so that the total reflection mirror 80 can be manually positioned between the cavity 20 and the narrowband module 32 .

[0201] 7.2 Action

[0202] Figure 11 1 is a flowchart showing the process of the line sensor degradation determination method. Here, an example of determining degradation of the line sensor 53 of the narrowband laser device 3 will be described.

[0203] In step S51, the laser control unit 61 initializes various parameters. Here, the laser control unit 61 sets the determination result flag to false, sets the threshold value TH to 0.8, and sets the arrays N_Fspectol[1] to N_Fspectol

[512] to 0.0.

[0204] In addition, the laser control unit 61 needs to obtain in advance the free oscillation spectrum of the line sensor 53 in a state without degradation, but this will be described later.

[0205] In step S52 , the laser control unit 61 sets the oscillation pulse energy PE to 10 mJ.

[0206] In step S53, the laser control unit 61 uses the advancing and retracting mechanism to insert the total reflection mirror 80 between the cavity 20 and the bandwidth narrowing module 32 (an example of an insertion step). This forms a laser resonator composed of the total reflection mirror 80 and the output coupling mirror 30, which is capable of free oscillation at an oscillation pulse energy PE. The free oscillating laser light (an example of non-narrowed laser light) is incident on the coarse etalon 48.

[0207] Laser control unit 61 substitutes the measured value of each pixel of line sensor 53 into arrays Fspectol[1] to Fspectol

[512] to obtain the intensity distribution of the fringe waveform (an example of the intensity distribution acquisition step). Here, the fringe waveform generated on the light-receiving surface of line sensor 53 is called a spectrum waveform, and the intensity distribution obtained from line sensor 53 is called a free oscillation spectrum.

[0208] The laser control unit 61 similarly obtains the free oscillation spectrum (an example of the reference intensity distribution) in the non-degraded state of the line sensor 53 in advance (an example before the determination step). That is, the laser control unit 61 sets the oscillation pulse energy PE to 10 mJ, performs free oscillation, and substitutes the measured values of each pixel of the non-degraded line sensor 53 into the arrays Fspectol_ref[1] to Fspectol_ref

[512] (an example of the reference intensity distribution acquisition step). The laser control unit 61 causes a memory (not shown) to store the values of the arrays Fspectol_ref[1] to Fspectol_ref

[512] (an example of the storage step). The free oscillation spectrum in the non-degraded state of the line sensor 53 may also be obtained not by the laser control unit 61 but by a computer for inspection (an example of a processor) at the time of factory shipment by the manufacturer. The free oscillation spectrum in the non-degraded state of the line sensor 53 is referred to as the reference free oscillation spectrum.

[0209] In step S54, the laser control unit 61 initializes the index i indicating the pixel position of the line sensor 53 to 0. [[ID=,5]]

[0210] In step S55, the laser control unit 61 updates the index i by adding 1.

[0211] In step S56, the laser control unit 61 calculates the normalized free oscillation spectrum (an example of the degradation parameter acquisition step) obtained by normalizing the value of the array Fspectol[i] using the value of the array Fspectol_ref[i]. Here, the value of Fspectol[i] / Fspectol_ref[i] is substituted into the array N_Fspectol[i].

[0212] In step S57, the laser control unit 61 compares the value of the array N_Fspectol[i] (an example of the degradation parameter) with the threshold TH (an example of the comparison step), and determines whether the threshold TH is greater than the value of the array N_Fspectol[i]. When N_Fspectol[i]<TH is satisfied, the laser control unit 61 performs the process of step S59 after performing the process of step S58. When N_Fspectol[i]<TH is not satisfied, the laser control unit 61 performs the process of step S59.

[0213] In step S58, the laser control unit 61 makes the determination result flag true (an example of the output step).

[0214] In step S59, the laser control unit 61 determines whether the index i is 512. When i = 512 is not satisfied, the laser control unit 61 performs the process of step S55. When i = 512 is satisfied, the laser control unit 61 ends the process of this flowchart.

[0215] When the processes of step S56 and step S57 are repeatedly performed and N_Fspectol[i]<TH is satisfied at least once, in step S58, the determination result flag becomes true. That is, when at least one of the values of the degradation parameters is less than the threshold TH, the laser control unit 61 determines that the line sensor 53 is degraded and outputs a signal prompting replacement of the monitor module 40.

[0216] Figure 12 It is a diagram showing an example of the free oscillation spectrum in a non-degraded state. F12A is the reference free oscillation spectrum, the horizontal axis is the pixel position of the line sensor 53, and the vertical axis is the measured value. F12B is the normalized free oscillation spectrum obtained by normalizing the reference free oscillation spectrum of F12A, the horizontal axis is the pixel position of the line sensor 53, and the vertical axis is the ratio relative to the reference (unit: %).

[0217] Figure 13 It is a diagram showing an example of the free oscillation spectrum in a degraded state. F13A is the free oscillation spectrum, the horizontal axis is the pixel position of the line sensor 53, and the vertical axis is the measured value. F13B is the normalized free oscillation spectrum obtained by normalizing the free oscillation spectrum of F13A using the reference free oscillation spectrum, the horizontal axis is the pixel position of the line sensor 53, and the vertical axis is the ratio relative to the reference (unit: %).

[0218] In Figure 13 In the example shown, there are pixels in the normalized free oscillation spectrum whose ratio relative to the reference is less than 0.8. If the threshold TH is set to 0.8, the determination result flag becomes true, and the laser control unit 61 outputs a signal prompting replacement of the monitor module 40.

[0219] 7.3 Function / Effect

[0220] Changing the wavelength in a range wider than the FSRc of the coarse etalon 48 as in Embodiment 2 is an operation that is desired to be avoided in the control of the narrowband laser device 3. This is because when changing the wavelength beyond the FSRc, it is difficult to maintain the pulse energy constant over the entire wavelength range, and there is a risk of overlooking the fringe order of the coarse etalon 48. According to Embodiment 3, the oscillation wavelength is not changed, and thus, the above difficulties and risks are not accompanied.

[0221] According to Embodiment 3, by using the normalized free oscillation spectrum obtained by normalizing the free oscillation spectrum using the reference free oscillation spectrum, it is possible to quantitatively evaluate the sensitivity degradation of each pixel of at least one of the line sensor 52 and the line sensor 53.

[0222] 8. Embodiment 4

[0223] 8.1 Structure

[0224] The hardware configuration of the fourth embodiment is the same as that of the narrowband laser device 1. The narrowband laser device 1 includes a switch (not shown) for switching the power supply of the device on and off.

[0225] 8.2 Action

[0226] The laser control unit 61 periodically performs the line sensor degradation determination method of Embodiment 1 to obtain the FC_diff profile. The laser control unit 61 analyzes the trend (transition) of the degradation amount relative to the number of shots in the obtained FC_diff profile to predict the replacement time for the monitor module 40 (the number of shots that reaches a predetermined degradation amount).

[0227] For example, the laser control unit 61 performs the line sensor degradation determination method of Embodiment 1 during periodic maintenance of the monitor module 40 based on a pulse rate of 20 Bpls (billion pulses) to 50 Bpls. Alternatively, the laser control unit 61 automatically performs the line sensor degradation determination method of Embodiment 1 (an example of a control step) at least one of power-on and power-off of the narrowband laser device 1 and laser gas replacement.

[0228] Figure 14 This is a diagram for explaining prediction of the replacement timing of the monitor module 40 , where the horizontal axis represents the number of shots and the vertical axis represents the amount of degradation. Figure 14 A threshold value TH is also shown. Figure 14 The circular plotted points of F14A and the solid line represent the degradation amount trend of the maximum value of ABS|FC_diff[i]|, and the dotted line represents a model obtained by linearly approximating the degradation amount trend.

[0229] The laser control unit 61 predicts the time when the model obtained by linearly approximating the degradation amount trend reaches the threshold value TH as the life of at least one of the line sensor 52 and the line sensor 53 , that is, the replacement time of the monitor module 40 (an example of a prediction step).

[0230] The laser control unit 61 may periodically perform the line sensor degradation determination method of the second embodiment and analyze the trend of the degradation amount with respect to the number of shots of the normalized U profile to thereby predict the replacement time of the monitor module 40 .

[0231] Figure 14 The circular plot points and the solid line in F14B represent the degradation amount trend of the minimum value of the array Uprofile[i], and the dotted line represents a model obtained by linearly approximating the degradation amount trend.

[0232] In the narrowband laser device 3, the laser control unit 61 can also periodically implement the processing of the line sensor degradation judgment method of embodiment 3, analyze the trend of the degradation amount relative to the number of shots of the normalized free oscillation spectrum, and thereby predict the time point when the model obtained by linearly approximating the degradation amount trend reaches the threshold TH, and predict the replacement period of the monitor module 40.

[0233] Figure 14 The circular plot points and the solid line of F14C represent the degradation amount trend of the minimum value of the array N_Fspectol[i], and the dotted line represents a model obtained by linearly approximating the degradation amount trend.

[0234] By using these models, the number of shots that will reach the threshold value TH can be predicted as the replacement timing of the monitor module 40 .

[0235] 8.3 Action / Effect

[0236] According to the fourth embodiment, the replacement time of the monitor module 40 can be known, thereby avoiding unnecessary replacement of the monitor module 40. Furthermore, the replacement time of the monitor module 40 can be accurately predicted, and thus can be reflected in the operation plan and maintenance schedule of the narrowband laser device 1. This can shorten the downtime of the process, thereby reducing chip costs.

[0237] 9. Implementation Method 5

[0238] 9.1 Structure

[0239] Figure 15 : is a figure which shows the structure of the laser system 4. The laser system 4 includes a display 82, a user PC (Personal Computer) 83, and a laser manufacturer PC 84.

[0240] The display 82 is, for example, a Patlite (registered trademark) or a display. The user PC 83 is a computer used by the user of the narrowband laser device 1 and is communicatively connected to the laser control unit 61. The laser manufacturer PC 84 is a maintenance computer used by the service personnel of the manufacturer of the narrowband laser device 2 and is communicatively connected to the laser control unit 61.

[0241] Figure 16 1 is a diagram showing the configuration of a laser system 5 as a modified example of the laser system 4. The laser system 5 includes a server 85. The server 85 is arranged between the laser control unit 61, the user PC 83, and the laser manufacturer PC 84, and is connected to the laser control unit 61, the user PC 83, and the laser manufacturer PC 84 in a communicable manner.

[0242] The laser system 4 and the laser system 5 may include the narrow-band laser device 2 or the narrow-band laser device 3 instead of the narrow-band laser device 1 .

[0243] 9.2 Action

[0244] The laser system 4 and the laser system 5 use at least one of the degradation determination result data, the degradation parameter, and the device status data.

[0245] The degradation determination result data includes at least one of a determination result flag and a threshold value TH. The degradation parameter includes at least one of an FC_diff profile, a normalized U profile, and a normalized free oscillation spectrum. The device status data includes at least one of the time when the processing of the line sensor degradation determination method of embodiments 1 to 3 is implemented, the number of laser oscillation shots (pulse number), and the number of shots sampled by the monitor module 40. The laser system 4 and the laser system 5 obtain the device status data (an example of a status acquisition step) when the processing of the line sensor degradation determination method of embodiment 1 is implemented. The processing of the sensor degradation determination method may also be the processing of embodiment 2 or embodiment 3. The processing of the sensor degradation determination method of multiple embodiments may also be implemented.

[0246] The laser control unit 61 performs the processing of the line sensor degradation determination method of Embodiment 1. Based on the determination result flag, which is one piece of degradation determination result data, the laser control unit 61 displays on the display 82 whether or not at least one of the line sensor 52 and the line sensor 53 has degraded, thereby notifying the user. Furthermore, the laser control unit 61 may also display the threshold value TH, which is one piece of degradation determination result data, on the display 82.

[0247] Furthermore, the user PC 83 and the laser manufacturer PC 84 can also obtain degradation determination result data from the laser control unit 61 and respectively implement the line sensor degradation determination method. The user PC 83 and the laser manufacturer PC 84 can also obtain degradation parameters from the laser control unit 61 to determine the degree of degradation of at least one of the line sensors 52 and 53. The user PC 83 and the laser manufacturer PC 84 can also obtain degradation determination result data, degradation parameters, and status data from the laser control unit 61 and respectively implement the prediction of the replacement time of the monitor module 40 described in Embodiment 4.

[0248] Furthermore, when using the laser system 5, the server 85 has a data buffering function. Therefore, degradation determination result data, degradation parameters, and status data can be stored for a long period of time, asynchronously with the processing of the line sensor degradation determination method of embodiments 1 to 3. These data can also be shared among the laser control unit 61, the user PC 83, and the laser manufacturer's PC 84. This data storage and sharing allows users and laser manufacturers to efficiently analyze the data. This analysis can contribute to efficient device operation and reduce downtime.

[0249] 9.3 Action / Effect

[0250] According to the laser system 4 or the laser system 5 , degradation information of at least one of the line sensor 52 and the line sensor 53 is effectively provided to the outside of the narrowband laser device 1 , thereby enabling efficient operation of the narrowband laser device 1 .

[0251] 10. Method for manufacturing electronic devices

[0252] Figure 17 300 is a diagram schematically showing a configuration example of the exposure apparatus 302. The method for manufacturing an electronic device is realized by the excimer laser apparatus 300 and the exposure apparatus 302.

[0253] The excimer laser device 300 may include the narrowband laser device 1, narrowband laser device 2, or narrowband laser device 3 described in each embodiment. The excimer laser device 300 may be connected to at least one of the display 82, the user PC 83, the laser manufacturer PC 84, and the server 85.

[0254] The pulse laser light output from the excimer laser device 300 is input to the exposure device 302 and used as exposure light.

[0255] The exposure device 302 includes an illumination optical system 304 and a projection optical system 306. The illumination optical system 304 illuminates the mask pattern on the mask stage RT by the pulsed laser incident from the excimer laser device 300. The projection optical system 306 performs a reduced projection of the pulsed laser after passing through the mask so that it is imaged on a workpiece (not shown) arranged on the workpiece stage WT. The workpiece is a photosensitive substrate such as a semiconductor wafer coated with a photoresist. The exposure device 302 causes the mask stage RT and the workpiece stage WT to move synchronously and parallel to each other, thereby exposing the workpiece to the pulsed laser reflecting the mask pattern. By transferring the device pattern on the semiconductor wafer through the above exposure steps, a semiconductor device can be manufactured. A semiconductor device is an example of an "electronic device" in the present disclosure.

[0256] 11. Others

[0257] The above description is not limiting but merely illustrative. Therefore, those skilled in the art will appreciate that modifications can be made to the embodiments of the present disclosure without departing from the scope of the claims. Furthermore, those skilled in the art will appreciate that combinations of the embodiments of the present disclosure can be used.

[0258] Unless otherwise expressly stated, the terms used in this specification and claims as a whole should be interpreted as “non-limiting” terms. For example, terms such as “including”, “having”, “having”, and “equipped” should be interpreted as “excluding the presence of structural elements other than the structural elements to be recorded”. In addition, the modifier “one” should be interpreted as meaning “at least one” or “one or more”. In addition, terms such as “at least one of A, B, and C” should be interpreted as “A”, “B”, “C”, “A+B”, “A+C”, “B+C”, or “A+B+C”. Furthermore, it should be interpreted as also including combinations of these and parts other than “A”, “B”, and “C”.

Claims

1. A method for determining sensor degradation, comprising the following steps: a determination step in which the processor determines degradation of at least one of a coarse sensor that receives interference fringes generated by a coarse spectrometer and a fine sensor that receives interference fringes generated by a fine spectrometer having a higher resolution than the coarse spectrometer; as well as output step, wherein the processor outputs the result of the determination, The determination step comprises the following steps: a step of obtaining a rough measurement wavelength, sequentially causing a plurality of laser beams having different wavelengths to be incident on the rough spectrometer, and obtaining a rough measurement wavelength for each wavelength based on a plurality of interference fringes sequentially received by the rough sensor; a fine measurement wavelength acquisition step of sequentially causing the plurality of laser beams to be incident on the fine spectrometer and acquiring a fine measurement wavelength for each wavelength based on a plurality of interference fringes sequentially received by the fine sensor; a degradation parameter obtaining step of obtaining the degradation parameter of each wavelength based on the coarse measurement wavelength of each wavelength and the fine measurement wavelength of each wavelength; and The comparison step is to compare the degradation parameter of each wavelength with a threshold value.

2. The sensor degradation determination method according to claim 1, wherein: In the degradation parameter acquisition step, the degradation parameter for each wavelength is calculated based on a difference between a coarse measurement wavelength for each wavelength and a fine measurement wavelength for each wavelength.

3. The sensor degradation determination method according to claim 1, wherein: Regarding the plurality of laser beams, a difference in wavelength between the laser beam having the shortest wavelength and the laser beam having the longest wavelength is smaller than a free spectral range of the roughing spectrometer.

4. The sensor degradation determination method according to claim 3, wherein: The wavelengths of the plurality of laser beams are different from each other by an interval in the free spectrum range of the fine spectrometer.

5. The sensor degradation determination method according to claim 1, wherein: The sensor degradation determination method includes a branching step of branching a plurality of laser beams having different wavelengths into the plurality of laser beams incident on the rough spectrometer and the plurality of laser beams incident on the fine spectrometer.

6. The sensor degradation determination method according to claim 1, wherein: The pulse energies of the plurality of lasers are respectively constant.

7. The sensor degradation determination method according to claim 1, wherein: The rough spectrometer includes at least one of an etalon and a grating.

8. The sensor degradation determination method according to claim 1, wherein: The fine spectrometer includes an etalon.

9. The sensor degradation determination method according to claim 1, wherein: The comparing step includes a predicting step of predicting the life of at least one of the coarse sensor and the fine sensor based on the transition of the degradation parameter for each wavelength.

10. The sensor degradation determination method according to claim 1, wherein: The comparing step includes a predicting step of comparing the transition of the degradation parameter for each wavelength with the threshold value to predict the life of at least one of the coarse sensor and the fine sensor.

11. The sensor degradation determination method according to claim 1, wherein: In the output step, the result of the determination is displayed on a display.

12. The sensor degradation determination method according to claim 1, wherein: The coarse sensor and the fine sensor are respectively line sensors.

13. The sensor degradation determination method according to claim 1, wherein: The laser device for emitting the laser light has: a switch that switches the power supply of the laser device on and off; and A cavity containing laser gas, The sensor degradation determination method includes a control step of causing the processor to perform the determination step at least one of when the laser device is maintained, when the power is turned on, when the power is turned off, and when the laser gas is replaced.

14. The sensor degradation determination method according to claim 13, wherein: The sensor degradation determination method includes a state acquisition step, in which at least one of the time when the determination step is performed, the number of laser oscillations of the laser device, and the number of samplings of the coarse spectrometer and the fine spectrometer is acquired.

15. A method for determining sensor degradation, comprising the following steps: a determination step in which the processor determines degradation of a sensor that receives interference fringes generated by the spectrometer; and output step, wherein the processor outputs the result of the determination, The determination step comprises the following steps: an intensity distribution obtaining step of sequentially causing a plurality of laser beams having different wavelengths to be incident on the spectrometer to obtain a plurality of intensity distributions corresponding to a plurality of interference fringes sequentially received by the sensor; a profile obtaining step of obtaining a profile of each pixel of the sensor according to the plurality of intensity distributions; a degradation parameter obtaining step of obtaining a degradation parameter of each pixel obtained by normalizing the profile of each pixel; as well as The comparison step is to compare the degradation parameter of each pixel with a threshold.

16. The sensor degradation determination method according to claim 15, wherein: In the profile acquisition step, a profile of the maximum value of each pixel of the sensor is acquired. In the degradation parameter acquisition step, the profile of the maximum value is normalized using an average value of the maximum values ​​of the pixels of the sensor.

17. The sensor degradation determination method according to claim 15, wherein: A difference in wavelength between the laser light with the shortest wavelength and the laser light with the longest wavelength among the plurality of laser lights is larger than a free spectral range of the spectrometer.

18. A method for determining sensor degradation, comprising the following steps: a determination step in which the processor determines degradation of a sensor that receives interference fringes generated by the spectrometer; and output step, wherein the processor outputs the result of the determination, The determination step comprises the following steps: an intensity distribution obtaining step of causing the non-narrowband laser to be incident on the spectrometer to obtain the intensity distribution of the interference fringes received by the sensor; a degradation parameter acquisition step of normalizing the acquired intensity distribution using a reference intensity distribution to acquire a degradation parameter for each pixel of the sensor; and The comparison step is to compare the degradation parameter of each pixel with a threshold.

19. The sensor degradation determination method according to claim 18, wherein: The sensor degradation determination method comprises the following steps: a reference intensity distribution obtaining step, prior to the determining step, causing the non-narrowband laser light to be incident on the spectrometer, and the processor obtaining the reference intensity distribution based on interference fringes received by the sensor; and In the storing step, the processor causes a memory to store the reference intensity distribution.

20. The sensor degradation determination method according to claim 18, wherein: The laser device for emitting the non-narrowband laser light comprises: a cavity having a pair of discharge electrodes disposed therein and containing laser gas, the cavity including a first window and a second window; a narrowband optical system disposed on an optical path of light emitted from the first window; as well as an output coupling mirror which, together with the narrowband optical system, constitutes a laser resonator, the output coupling mirror being arranged on the optical path of the light emitted from the second window and causing a portion of the light emitted from the second window to be emitted; The intensity distribution acquisition step includes an inserting step of inserting a total reflection mirror between the narrowband optical system of the laser device and the cavity.

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