Laser device, method for evaluating spectrum of laser light, and method for manufacturing electronic device

Abstract

A laser device that can be connected to an exposure device, said laser device comprising: a spectrometer that generates a measurement waveform from an interference pattern of laser light output from the laser device; and a processor, said processor being configured to calculate a first spectrum waveform representing the relationship between wavelength and light intensity using the measurement waveform, to calculate a representative wavelength included in a wavelength region of the first spectrum waveform, and to calculate an evaluation value of the first spectrum waveform using a first integrated value obtained by integrating, with respect to the wavelength region, the product of light intensity and a function of wavelength deviation from the representative wavelength.

Description

[Technical field]

[0001] The present disclosure relates to a laser apparatus, a method for evaluating the spectrum of laser light, and a method for manufacturing an electronic device. [Background technology]

[0002] In recent years, semiconductor exposure devices are required to improve their resolution in accordance with the miniaturization and high integration of semiconductor integrated circuits. For this reason, the wavelength of light emitted from the exposure light source is being shortened. For example, as gas laser devices for exposure, KrF excimer laser devices that output laser light with a wavelength of about 248 nm and ArF excimer laser devices that output laser light with a wavelength of about 193 nm are used.

[0003] The spectral line width of the spontaneous oscillation light of the KrF excimer laser device and the ArF excimer laser device is as wide as 350 to 400 pm. Therefore, if a projection lens is made of 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 line width of the laser light output from the gas laser device to a level where the chromatic aberration can be ignored. Therefore, in order to narrow the spectral line width, a line narrow module (LNM) including a line narrowing element (such as an etalon or grating) may be provided in the laser resonator of the gas laser device. Hereinafter, a gas laser device in which the spectral line width is narrowed is referred to as a line narrowing gas laser device. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] US Patent Application Publication No. 2011 / 200922 [Patent Document 2] Summary of U.S. Patent Application Publication No. 2012 / 057144

[0005] A laser apparatus according to one aspect of the present disclosure is a laser apparatus connectable to an exposure apparatus, and includes: a spectrometer that generates a measurement waveform from an interference pattern of laser light output from the laser apparatus; and a processor configured to calculate a first spectral waveform indicating a relationship between wavelength and light intensity using the measurement waveform, calculate a representative wavelength included in a wavelength range of the first spectral waveform, and calculate an evaluation value of the first spectral waveform using a first integral value obtained by integrating, over the wavelength range, the product of a function of wavelength deviation from the representative wavelength and the light intensity.

[0006] A method for evaluating the spectrum of laser light according to one aspect of the present disclosure includes generating a measurement waveform from an interference pattern of laser light output from a laser device connectable to an exposure device, calculating a first spectral waveform indicating a relationship between wavelength and light intensity using the measurement waveform, calculating a representative wavelength included in a wavelength range of the first spectral waveform, and calculating an evaluation value of the first spectral waveform using a first integral value obtained by integrating, over the wavelength range, the product of a function of wavelength deviation from the representative wavelength and the light intensity.

[0007] A method for manufacturing an electronic device according to one aspect of the present disclosure includes generating laser light using a laser apparatus including a spectrometer that generates a measurement waveform from an interference pattern of laser light output from a laser apparatus connectable to an exposure apparatus, and a processor configured to calculate a first spectral waveform indicating a relationship between wavelength and light intensity using the measurement waveform, calculate a representative wavelength included in a wavelength range of the first spectral waveform, and calculate an evaluation value of the first spectral waveform using a first integral value obtained by integrating a product of a function of wavelength deviation from the representative wavelength and the light intensity over the wavelength range, outputting the laser light to the exposure apparatus, and exposing the laser light onto a photosensitive substrate in the exposure apparatus to manufacture an electronic device. [Brief description of the drawings]

[0008] Some embodiments of the present disclosure will now be described, by way of example only, with reference to the accompanying drawings. [Figure 1]FIG. 1 shows a schematic configuration of an exposure system in a comparative example. [Diagram 2] FIG. 2 is a schematic diagram showing the configuration of a laser device according to a comparative example. [Diagram 3] FIG. 3 is a block diagram illustrating the function of the spectrum measurement control processor in the comparative example. [Figure 4] FIG. 4 is a flowchart showing the procedure for measuring the spectral linewidth E95 in the comparative example. [Diagram 5] FIG. 5 is a graph showing an example of an estimated spectral waveform I(λ) of laser light. [Figure 6] FIG. 6 is a graph showing another example of the spectral waveform of the laser beam. [Figure 7] FIG. 7 is a graph showing the distribution of focus positions in an exposure apparatus for the laser light shown by the spectral waveform #1 in FIG. [Figure 8] FIG. 8 is a graph showing the distribution of focus positions in an exposure apparatus for the laser light shown by the spectral waveform #2 in FIG. [Figure 9] FIG. 9 is a graph showing the distribution of focus positions in an exposure apparatus for the laser light shown by the spectral waveform #3 in FIG. [Figure 10] FIG. 10 is a graph showing still another example of the spectral waveform of laser light. [Figure 11] FIG. 11 is a graph showing still another example of the spectral waveform of laser light. [Figure 12] FIG. 12 shows the rectangular imaging pattern used to evaluate the imaging performance. [Figure 13] FIG. 13 is a graph showing the results of a simulation of the imaging performance in an exposure apparatus. [Figure 14] FIG. 14 is a graph showing the results of a simulation of the imaging performance in an exposure apparatus. [Figure 15] FIG. 15 is a schematic diagram showing a configuration of a laser device according to an embodiment of the present disclosure. [Figure 16]FIG. 16 is a flowchart showing the procedure for measuring the spectrum evaluation value V in this embodiment. [Figure 17] FIG. 17 shows the imaging patterns used to compare the usefulness of the spectral evaluation value V and the spectral linewidth E95. [Figure 18] FIG. 18 is a graph showing the relationship between the spectral linewidth E95 and ΔCD in the imaging pattern of FIG. [Figure 19] FIG. 19 is a graph showing the relationship between the spectrum evaluation value V and ΔCD in the imaging pattern of FIG. [Figure 20] FIG. 20 shows another imaging pattern used to compare the usefulness of the spectral evaluation value V and the spectral linewidth E95. [Figure 21] FIG. 21 is a graph showing the relationship between the spectral linewidth E95 and ΔCD in the imaging pattern of FIG. [Figure 22] FIG. 22 is a graph showing the relationship between the spectrum evaluation value V and ΔCD in the imaging pattern of FIG. [Diagram 23] FIG. 23 is a graph showing the relationship between the spectrum evaluation value V of Equation 4 and ΔCD in the imaging pattern of FIG. [Figure 24] FIG. 24 is a graph showing the relationship between the spectrum evaluation value V of Equation 4 and ΔCD in the imaging pattern of FIG. [Diagram 25] FIG. 25 is a flowchart showing a procedure of spectrum control in the embodiment. [Figure 26] FIG. 26 shows a schematic configuration of a modified example of the spectral waveform adjuster. [Figure 27] FIG. 27 shows a schematic configuration of a modified example of the spectral waveform adjuster. Embodiment

[0009] <Contents> 1. Comparative Example 1.1 Configuration of exposure apparatus 100 1.2 Operation of Exposure Apparatus 100 1.3 Configuration of laser device 1 1.3.1 Laser oscillator 20 1.3.2 Monitor Module 16 1.3.3 Various processing equipment 1.4 Operation 1.4.1 Laser Control Processor 30 1.4.2 Laser oscillator 20 1.4.3 Monitor Module 16 1.4.4 Wavelength measurement control unit 50 1.4.5 Spectral Measurement Control Processor 60 1.5 Issues in Comparative Examples 2. Estimated spectrum waveform I(λ) and wavelength deviation function (λ-λc) 2 Laser device 1a calculates a spectrum evaluation value V by integrating the product of 2.1 Configuration 2.2 Measurement of spectrum evaluation value V 2.3 Spectral linewidth: Comparison with E95 2.4 Modification of the spectrum evaluation value V 2.5 Spectral Control Operation 2.6 Spectral Shape Adjuster Variations 2.6.1 Configuration 2.6.2 Operation 2.6.3 Other configuration examples 2.7 Effect 3.Other

[0010] Hereinafter, the 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 contents of the present disclosure. Furthermore, not all of the configurations and operations described in each embodiment are necessarily essential as the configurations and operations of the present disclosure. Note that the same components are given the same reference symbols, and duplicated explanations will be omitted.

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

[0012] The exposure system includes a laser device 1 and an exposure device 100. The laser device 1 includes a laser control processor 30. The laser control processor 30 is a processing device including a memory 132 in which a control program is stored, and a CPU (central processing unit) 131 that executes the control program. The laser control processor 30 is specially configured or programmed to execute various processes included in the present disclosure. The laser device 1 is configured to output laser light toward the exposure device 100.

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

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

[0015] 1.2 Operation of Exposure Apparatus 100 The exposure control processor 110 transmits data on the target value of the wavelength, data on the target value of the pulse energy, and a trigger signal to the laser control processor 30. The laser control processor 30 controls the laser device 1 in accordance with these data and signals. Exposure control processor 110 translates reticle stage RT and workpiece table WT in parallel in opposite directions in synchronization with each other, whereby the workpiece is exposed to laser light reflecting the reticle pattern. The reticle pattern is transferred onto the semiconductor wafer through this exposure process, after which electronic devices can be manufactured through multiple processes.

[0016] 1.3 Configuration of laser device 1 2 is a schematic diagram showing the configuration of a laser apparatus 1 according to a comparative example. The laser apparatus 1 includes a laser oscillator 20, a power supply 12, a monitor module 16, a laser control processor 30, a wavelength measurement control unit 50, and a spectrum measurement control processor 60. The laser apparatus 1 is connectable to an exposure apparatus 100.

[0017] 1.3.1 Laser oscillator 20 The laser oscillator 20 includes a laser chamber 10, a discharge electrode 11a, a line narrowing module 14, and a spectral waveform adjuster 15a. The line narrowing module 14 and the spectral waveform adjuster 15a constitute a laser resonator. The laser chamber 10 is disposed in the optical path of the laser resonator. Windows 10a and 10b are provided at both ends of the laser chamber 10. Inside the laser chamber 10, a discharge electrode 11a and a discharge electrode (not shown) that forms a pair with the discharge electrode 11a are disposed. The discharge electrode (not shown) is positioned so as to overlap with the discharge electrode 11a in the direction of the V axis perpendicular to the paper surface. The laser chamber 10 is filled with a laser gas that includes, for example, argon gas or krypton gas as a rare gas, fluorine gas as a halogen gas, and neon gas as a buffer gas.

[0018] The power supply 12 includes a switch 13, and is connected to the discharge electrode 11a and a charger (not shown).

[0019] The line narrowing module 14 includes a plurality of prisms 14a and 14b and a grating 14c. The prism 14b is supported by a rotation stage 14e. The rotation stage 14e is configured to rotate the prism 14b around an axis parallel to the V axis in accordance with a drive signal output from a wavelength driver 51. The selected wavelength of the line narrowing module 14 changes by rotating the prism 14b.

[0020] The spectral waveform adjuster 15a includes a cylindrical plano-convex lens 15b, a cylindrical plano-concave lens 15c, and a linear stage 15d. The cylindrical plano-concave lens 15c is located between the laser chamber 10 and the cylindrical plano-convex lens 15b. The cylindrical plano-convex lens 15b and the cylindrical plano-concave lens 15c are arranged so that the convex surface of the cylindrical plano-convex lens 15b faces the concave surface of the cylindrical plano-concave lens 15c. The convex surface of the cylindrical plano-convex lens 15b and the concave surface of the cylindrical plano-concave lens 15c each have a focal axis parallel to the V-axis. The flat surface opposite the convex surface of the cylindrical plano-convex lens 15b is coated with a partially reflective film.

[0021] 1.3.2 Monitor Module 16 The monitor module 16 is disposed in the optical path of the laser light between the spectral waveform adjuster 15a and the exposure apparatus 100. The monitor module 16 includes beam splitters 16a, 16b, and 17a, an energy sensor 16c, a high-reflection mirror 17b, a wavelength detector 18, and a spectrometer 19.

[0022] Beam splitter 16a is located in the optical path of the laser light output from spectral waveform adjuster 15a. Beam splitter 16a is configured to transmit a part of the laser light output from spectral waveform adjuster 15a toward exposure apparatus 100 with high transmittance and reflect the other part. Beam splitter 16b is located in the optical path of the laser light reflected by beam splitter 16a. Energy sensor 16c is located in the optical path of the laser light reflected by beam splitter 16b.

[0023] Beam splitter 17a is located in the optical path of the laser light transmitted through beam splitter 16b. High-reflection mirror 17b is located in the optical path of the laser light reflected by beam splitter 17a.

[0024] The wavelength detector 18 is disposed in the optical path of the laser light transmitted through the beam splitter 17a. The wavelength detector 18 includes a diffusion plate 18a, an etalon 18b, a condenser lens 18c, and a line sensor 18d.

[0025] The diffusion plate 18a is located in the optical path of the laser light transmitted through the beam splitter 17a. The diffusion plate 18a has a large number of projections and recesses on its surface, and is configured to transmit and diffuse the laser light. The etalon 18b is located in the optical path of the laser light transmitted through the diffusion plate 18a. The etalon 18b includes two partially reflecting mirrors. The two partially reflecting mirrors face each other with a predetermined air gap between them and are bonded together via a spacer.

[0026] The condenser lens 18c is located in the optical path of the laser light transmitted through the etalon 18b. The line sensor 18d is an optical path of the laser light transmitted through the condenser lens 18c, and is located on the focal plane of the condenser lens 18c. The line sensor 18d is an optical distribution sensor including a large number of light receiving elements arranged one-dimensionally. Alternatively, instead of the line sensor 18d, an image sensor including a large number of light receiving elements arranged two-dimensionally may be used as the optical distribution sensor. The line sensor 18d may include a processor (not shown).

[0027] The line sensor 18d receives the interference fringes formed by the etalon 18b and the condenser lens 18c. The interference fringes are an interference pattern of laser light and have a concentric shape, and the square of the distance from the center of the concentric circle is proportional to the change in wavelength. A processor (not shown) may be configured to statistically process data reflecting the interference pattern and output the data.

[0028] The spectrometer 19 is disposed in the optical path of the laser light reflected by the high-reflection mirror 17b. The spectrometer 19 includes a diffusion plate 19a, an etalon 19b, a condenser lens 19c, and a line sensor 19d. The line sensor 19d may include a processor (not shown). These configurations are similar to the diffusion plate 18a, the etalon 18b, the condenser lens 18c, and the line sensor 18d included in the wavelength detector 18, respectively. However, the etalon 19b has a smaller free spectral range than the etalon 18b. In addition, the condenser lens 19c has a longer focal length than the condenser lens 18c.

[0029] 1.3.3 Various processing equipment The spectrum measurement control processor 60 is a processing device including a memory 61 in which a control program is stored, a CPU 62 that executes the control program, and a counter 63. The spectrum measurement control processor 60 is specially configured or programmed to execute various processes included in the present disclosure. The spectrum measurement control processor 60 corresponds to the processor in the present disclosure.

[0030] The memory 61 also stores various data for calculating the spectral linewidth. The various data includes the instrument function S(λ) of the spectrometer 19. The counter 63 counts the number of pulses of the laser light by counting the number of times an electrical signal including pulse energy data output from the energy sensor 16c is received. Alternatively, the counter 63 may count the number of pulses of the laser light by counting the oscillation trigger signal output from the laser control processor 30.

[0031] The wavelength measurement control unit 50 is a processing device including a memory (not shown) in which a control program is stored, a CPU (not shown) that executes the control program, and a counter (not shown). The counter included in the wavelength measurement control unit 50 also counts the number of pulses of the laser light, similar to the counter 63.

[0032] In this disclosure, the laser control processor 30, the wavelength measurement control unit 50, and the spectral measurement control processor 60 are described as separate components, but the laser control processor 30 may also serve as both the wavelength measurement control unit 50 and the spectral measurement control processor 60.

[0033] 1.4 Operation 1.4.1 Laser Control Processor 30 The laser control processor 30 receives setting data for the target pulse energy and the target wavelength of the laser light from an exposure control processor 110 included in the exposure apparatus 100 . The laser control processor 30 receives a trigger signal from the exposure control processor 110 .

[0034] The laser control processor 30 transmits setting data of the voltage to be applied to the discharge electrode 11a based on the target pulse energy to the power source 12. The laser control processor 30 transmits setting data of the target wavelength to the wavelength measurement control unit 50. In addition, the laser control processor 30 transmits an oscillation trigger signal based on the trigger signal to the switch 13 included in the power source 12.

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

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

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

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

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

[0040] The linear stage 15d included in the spectral waveform adjuster 15a moves the cylindrical plano-concave lens 15c along the optical path between the laser chamber 10 and the cylindrical plano-convex lens 15b in accordance with the drive signal output from the spectral driver 64. This changes the wavefront of the light traveling from the spectral waveform adjuster 15a to the line narrowing module 14. The change in the wavefront changes the spectral waveform and the spectral linewidth of the laser light.

[0041] 1.4.3 Monitor Module 16 The energy sensor 16c detects the pulse energy of the laser light, and outputs the pulse energy data to the laser control processor 30, the wavelength measurement control unit 50, and the spectrum measurement control processor 60. The pulse energy data is used by the laser control processor 30 to feedback control the setting data of the voltage applied to the discharge electrode 11a. In addition, the electrical signal including the pulse energy data can be used by the wavelength measurement control unit 50 and the spectrum measurement control processor 60 to count the number of pulses.

[0042] Wavelength detector 18 generates waveform data of interference fringes from the amount of light at each of the light receiving elements included in line sensor 18d. Wavelength detector 18 may use an integrated waveform obtained by integrating the amount of light at each of the light receiving elements as the waveform data of interference fringes. Wavelength detector 18 may generate an integrated waveform multiple times and use an average waveform obtained by averaging the multiple integrated waveforms as the waveform data of interference fringes. The wavelength detector 18 transmits waveform data of the interference fringes to the wavelength measurement control unit 50 in accordance with a data output trigger output from the wavelength measurement control unit 50 .

[0043] The spectroscope 19 generates a raw waveform reflecting the amount of light at each of the light receiving elements included in the line sensor 19d that received the interference fringes. Alternatively, the spectroscope 19 generates an integrated waveform Oi by integrating the raw waveform over Ni pulses. The spectroscope 19 generates the integrated waveform Oi Na times, and generates an average waveform Oa by averaging the Na integrated waveforms Oi. The number of integrated pulses Ni is, for example, 5 pulses or more and 8 pulses or less, and the number of averaging times Na is, for example, 5 times or more and 8 times or less.

[0044] The spectrometer 19 may generate the integrated waveform Oi and the average waveform Oa in response to a trigger signal output from the spectrometer measurement control processor 60. The memory 61 of the spectrometer measurement control processor 60 may store setting data for the integrated pulse number Ni and the averaging number Na. At least one of the raw waveform, the integrated waveform Oi, and the average waveform Oa corresponds to the measurement waveform in this disclosure.

[0045] The spectrometer 19 extracts a portion of the waveform corresponding to the free spectral range from the average waveform Oa. The extracted portion of the waveform indicates the relationship between the distance from the center of the concentric circles that make up the interference fringes and the light intensity. The spectrometer 19 obtains a measured spectral waveform O(λ) by performing coordinate conversion of this waveform into a relationship between wavelength and light intensity. The coordinate conversion of a portion of the average waveform Oa into a relationship between wavelength and light intensity is also referred to as mapping to a spectral space. The measured spectral waveform O(λ) corresponds to a second spectral waveform in this disclosure.

[0046] The spectrometer 19 transmits the measured spectral waveform O(λ) to the spectrum measurement control processor 60 in accordance with a data output trigger output from the spectrum measurement control processor 60 . Any or all of the process of calculating the integrated waveform Oi, the process of calculating the average waveform Oa, and the process of acquiring the measured spectral waveform O(λ) by mapping to the spectral space may be performed by the spectrum measurement control processor 60 rather than by the spectrometer 19. Both the process of generating the average waveform Oa and the process of acquiring the measured spectral waveform O(λ) may be performed by the spectrum measurement control processor 60 rather than by the spectrometer 19.

[0047] 1.4.4 Wavelength measurement control unit 50 The wavelength measurement control unit 50 receives setting data of the target wavelength from the laser control processor 30. In addition, the wavelength measurement control unit 50 calculates the central wavelength of the laser light using waveform data of the interference fringes output from the wavelength detector 18. The wavelength measurement control unit 50 feedback-controls the central wavelength of the laser light by outputting a control signal to a wavelength driver 51 based on the target wavelength and the calculated central wavelength.

[0048] 1.4.5 Spectral Measurement Control Processor 60 The spectrum measurement control processor 60 receives the measured spectrum waveform O(λ) from the spectrometer 19. Alternatively, the spectrum measurement control processor 60 may receive a raw waveform from the spectrometer 19, integrate and average the raw waveform, and map it into a spectral space to obtain the measured spectrum waveform O(λ). Alternatively, the spectrum measurement control processor 60 may receive an integrated waveform Oi from the spectrometer 19, average the integrated waveform Oi, and map it into a spectral space to obtain the measured spectrum waveform O(λ). Alternatively, the spectrum measurement control processor 60 may receive an average waveform Oa from the spectrometer 19, and map the average waveform Oa into a spectral space to obtain the measured spectrum waveform O(λ). The spectrum measurement control processor 60 calculates an estimated spectrum waveform I(λ) from the measured spectrum waveform O(λ) as follows.

[0049] FIG. 3 is a block diagram for explaining the function of the spectrum measurement control processor 60 in the comparative example. The spectrometer 19 has measurement characteristics specific to the device, and the measurement characteristics are expressed by an instrumental function S(λ) as a function of wavelength λ. Here, the measured spectral waveform O(λ) when laser light having an unknown spectral waveform T(λ) is incident on the spectrometer 19 having the instrumental function S(λ) and measured is expressed as a convolution integral of the unknown spectral waveform T(λ) and the instrumental function S(λ) as shown in the following formula 1.

number

[0050] The Fourier transform F(O(λ)) of a measured spectral waveform O(λ) is equal to the product of the Fourier transforms F(T(λ)) and F(S(λ)) of two functions T(λ) and S(λ), respectively, as follows: F(O(λ))=F(T(λ))×F(S(λ)) This is called the convolution theorem.

[0051] The spectrum measurement control processor 60 measures the instrumental function S(λ) of the spectrometer 19 in advance and stores it in the memory 61. To measure the instrumental function S(λ), coherent light having approximately the same wavelength as the central wavelength of the laser light output from the laser device 1 and having a narrow spectral linewidth that can be considered to be approximately a δ function is made incident on the spectrometer 19. The measured spectral waveform of the coherent light by the spectrometer 19 can be taken as the instrumental function S(λ).

[0052] The CPU 62 included in the spectrum measurement control processor 60 performs deconvolution integration on the measured spectral waveform O(λ) of the laser light using the instrument function S(λ) of the spectrometer 19. Deconvolution integration refers to a calculation process for estimating an unknown function that satisfies the convolution integration equation. The waveform obtained by deconvolution integration is referred to as the estimated spectral waveform I(λ). The estimated spectral waveform I(λ) corresponds to the first spectral waveform in this disclosure, and indicates the relationship between the wavelength and light intensity of the estimated unknown spectral waveform T(λ). The estimated spectral waveform I(λ) is represented by the symbol *, which represents the deconvolution integration. -1 It is expressed as follows using I(λ)=O(λ)* -1 S(λ)

[0053] Theoretically, the deconvolution integral can be calculated as follows. First, the following formula is derived from the convolution theorem. F(I(λ))=F(O(λ)) / F(S(λ)) By performing an inverse Fourier transform on both sides of this equation, the deconvolution integral can be calculated. That is, the symbol for the inverse Fourier transform is F -1 Then, the estimated spectral waveform I(λ) is expressed as follows: I(λ)=F -1 (F(O(λ)) / F(S(λ)))

[0054] However, in actual numerical calculations, deconvolution using Fourier transform and inverse Fourier transform is easily affected by noise components contained in the measurement data. Therefore, it is desirable to calculate the deconvolution using an iterative method that can suppress the influence of noise components, such as the Jacobi method or the Gauss-Seidel method.

[0055] 4 is a flow chart showing the procedure for measuring the spectral linewidth E95 in the comparative example. The spectrum measurement control processor 60 generates an integrated waveform Oi and an average waveform Oa from the interference pattern of the laser light as follows, and calculates an estimated spectral waveform I(λ) and the spectral linewidth E95. The definition of the spectral linewidth E95 will be described later with reference to FIG. 5.

[0056] In S331, the spectrum measurement control processor 60 reads the integrated pulse number Ni and the averaging number Na from the memory 61. In S332, the spectrum measurement control processor 60 receives a raw waveform reflecting the amount of light at each of the light receiving elements included in the line sensor 19d, and generates an integrated waveform Oi by integrating the raw waveform over the Ni pulses. In S333, the spectrum measurement control processor 60 generates an integrated waveform Oi Na times, and generates an average waveform Oa by averaging the Na integrated waveforms Oi. In S334, the spectrum measurement control processor 60 generates a measured spectrum waveform O(λ) by mapping the average waveform Oa into a spectral space.

[0057] In S335, the spectrum measurement control processor 60 reads the instrument function S(λ) of the spectrometer 19 from the memory 61. In S336, the spectrum measurement control processor 60 calculates an estimated spectrum waveform I(λ) by deconvoluting the measured spectrum waveform O(λ) with the instrumental function S(λ). In S337, the spectrum measurement control processor 60 calculates the spectral linewidth E95 from the estimated spectral waveform I(λ). The calculated spectral linewidth does not have to be E95, and may be the full width at half maximum. After S337, the spectrum measurement control processor 60 ends the process of this flowchart.

[0058] The spectral measurement control processor 60 receives the target value of the spectral linewidth E95 from the exposure control processor 110 via the laser control processor 30. The spectral measurement control processor 60 transmits a control signal to the spectral driver 64 based on the target value of the spectral linewidth E95 and the calculated spectral linewidth E95 to control the spectral waveform adjuster 15a, thereby feedback-controlling the spectral linewidth E95.

[0059] FIG. 5 is a graph showing an example of an estimated spectral waveform I(λ) of laser light. The horizontal axis of FIG. 5 indicates the wavelength deviation Δλ from the central wavelength. The estimated spectral waveform I(λ) is a waveform showing the light intensity of each wavelength component included in the wavelength range of the estimated spectral waveform I(λ). The value obtained by integrating the estimated spectral waveform I(λ) over a certain wavelength range is called the spectral energy in that wavelength range. The total width of the part that occupies 95% of the spectral energy of the entire wavelength range of the estimated spectral waveform I(λ) is called the spectral linewidth E95. FIG. 5 shows an estimated spectral waveform I(λ) of laser light with a spectral linewidth E95 of 0.3 pm. Since the refraction angle at the lens surface differs depending on the wavelength of the laser light, a difference in the spectral waveform leads to a difference in the exposure performance in the exposure apparatus 100. By controlling the spectral linewidth E95 based on a target value, the exposure performance can be stabilized.

[0060] 1.5 Issues in Comparative Examples FIG. 6 is a graph showing another example of the spectral waveform of laser light. The horizontal axis in FIG. 6 indicates the wavelength deviation Δλ from the central wavelength. The spectral linewidth E95 of the spectral waveforms #1 to #3 shown in FIG. 6 is all 0.3 pm, but these spectral waveforms #1 to #3 have different shapes. Spectral waveform #1 is a spectral distribution in which the central wavelength and the peak wavelength coincide. Spectral waveform #2 is an asymmetric spectral distribution in which the peak wavelength is shifted to the longer wavelength side than the central wavelength. The central wavelength here is, for example, 1 / e of the peak intensity. 2 Spectral waveform #3 is a symmetrical spectral distribution with two separate peak wavelengths.

[0061] 7 to 9 are graphs showing the distribution of focus positions in exposure apparatus 100 for the laser light shown by the spectral waveforms #1 to #3 shown in FIG. 6. In each of FIGS. 7 to 9, the vertical axis indicates the focus position along the Z axis shown in FIG. 1, and the horizontal axis indicates the light intensity of the wavelength component focused at each focus position. The longitudinal chromatic aberration of projection optical system 102 of exposure apparatus 100 is set to 250 nm / pm. In other words, the difference in focus position per wavelength difference of 1 pm is set to 250 nm.

[0062] The distribution shapes of the focus positions shown in Figures 7 to 9 correspond almost directly to the shapes of the spectral waveforms #1 to #3 shown in Figure 6. In Figure 7, the distribution shape has the most wavelength components focused at the position Z=0. In Figure 8, the distribution shape is asymmetric with the focus center located on the positive side of Z=0. In Figure 9, the distribution shape has peaks of the focused wavelength components separated into two positions. In this way, even if the spectral linewidth E95 is the same, the distribution shape of the focus position in the exposure tool 100 may differ, resulting in different exposure performance.

[0063] 10 and 11 are graphs showing further examples of the spectral waveforms of laser light. In each of FIG. 10 and FIG. 11, the horizontal axis indicates the wavelength deviation Δλ from the central wavelength. The spectral linewidths E95 of the spectral waveforms #4 to #6 shown in FIG. 10 and the spectral waveforms #7 to #9 shown in FIG. 11 are all 0.3 pm, but the shapes of these spectral waveforms #4 to #9 are different from each other. The spectral waveforms #4 to #6 have asymmetric spectral distributions in which the peak wavelength is shifted to the longer wavelength side than the central wavelength, and the differences between the central wavelength and the peak wavelength are different from each other. The spectral waveforms #7 to #9 are symmetric, but the curve of the spectral waveform #7 is gentler near the peak than the Gaussian distribution-like spectral waveform #1 (see FIG. 6). The spectral waveforms #8 and #9 have spectral distributions in which the peak wavelength is separated into two, and the differences between the central wavelength and the peak wavelength are different from each other.

[0064] The imaging performance of exposure apparatus 100 was evaluated as follows using spectral waveforms #4 to #9. Fig. 12 shows a rectangular imaging pattern used to evaluate the imaging performance. A mask was used that was designed so that a rectangular imaging pattern with a horizontal dimension of 38 nm and a vertical dimension of 76 nm was formed on the wafer surface by the projection optical system 102 when the Gaussian distribution-like spectral waveform #1 was used. The longitudinal chromatic aberration of the projection optical system 102 was set to 250 nm / pm. When the spectral waveforms #4 to #9 were used and the exposure dose was adjusted so that the horizontal dimension of the imaging pattern on the wafer surface was 38 nm, the deviation ΔCD of the vertical dimension from 76 nm was obtained by simulation.

[0065] Figures 13 and 14 are graphs showing simulation results of the imaging performance in exposure apparatus 100. Figure 13 shows the case where spectral waveforms #4 to #6 shown in Figure 10 are used, and Figure 14 shows the case where spectral waveforms #7 to #9 shown in Figure 11 are used. As shown in Fig. 13, the greater the difference between the central wavelength and the peak wavelength, and the greater the asymmetry, the greater the dimensional error on the wafer surface. Also, as shown in Fig. 14, even if the spectral distribution is symmetric, the greater the difference from the Gaussian distribution, the greater the dimensional error on the wafer surface.

[0066] In this way, even if the spectral linewidth E95 is the same, the imaging performance of exposure apparatus 100 may differ, and the desired exposure performance may not be obtained by simply adjusting the spectral linewidth E95 to a target value.

[0067] In the embodiment described below, a waveform evaluation is performed taking into consideration not only the spectral linewidth but also the shape of the spectral waveform, thereby enabling spectrum control to obtain the required exposure performance.

[0068] 2. Estimated spectrum waveform I(λ) and wavelength deviation function (λ-λc) 2 Laser device 1a calculates a spectrum evaluation value V by integrating the product of 2.1 Configuration 15 is a schematic diagram showing a configuration of a laser device 1a according to an embodiment of the present disclosure. In the laser device 1a, a memory 61 included in a spectrum measurement control processor 60 stores a spectrum evaluation value calculation program 611.

[0069] When the CPU 62 executes the spectrum evaluation value calculation program 611, the spectrum measurement control processor 60 performs the following calculations.

[0070] The spectrum measurement control processor 60 calculates the centroid wavelength λc of the estimated spectrum waveform I(λ) according to the following equation 2.

number

[0071] The spectrum measurement control processor 60 calculates the spectrum evaluation value V of the estimated spectrum waveform I(λ) according to the following equation 3.

number

[0072] The numerator of Equation 3 is a function of the light intensity shown by the estimated spectral waveform I(λ) and the wavelength deviation from the centroid wavelength λc (λ-λc). 2 The spectrum evaluation value V corresponds to the evaluation value in this disclosure.

[0073] The denominator of Equation 3 is the product of a constant λs and the third integral value. The constant λs may be any one of the following (1) to (4). (1)1 (2) Centroid wavelength λc (3) Spectral linewidth E95 of estimated spectrum waveform I(λ) (4) The standard deviation of a Gaussian-distributed spectral waveform with the same spectral linewidth E95 as the estimated spectral waveform I(λ)

[0074] When the constant λs is set to 1 as in (1) above, the spectral evaluation value V has the dimension of the square of the wavelength λ, whereas by dividing it by the constant λs obtained from a function of the wavelength λ as in (2) to (4) above, the spectral evaluation value V can be made to have the dimension of the wavelength λ.

[0075] 2.2 Measurement of spectrum evaluation value V Fig. 16 is a flowchart showing the procedure for measuring the spectrum evaluation value V in the embodiment. The processes of S331 to S336 in Fig. 16 are similar to the corresponding processes in Fig. 4. After S336, the spectrum measurement control processor 60 advances the process to S338. In S338, the spectrum measurement control processor 60 calculates the centroid wavelength λc of the estimated spectrum waveform I(λ) according to Equation 2. In S339, the spectrum measurement control processor 60 calculates the spectrum evaluation value V of the estimated spectrum waveform I(λ) according to Equation 3. After S339, the spectrum measurement control processor 60 ends the process of this flowchart.

[0076] 2.3 Spectral linewidth: Comparison with E95 Next, the spectral evaluation value V and the usefulness of the evaluation method using it will be described while comparing it with the spectral linewidth E95. As will be described below, the spectral evaluation value V can be applied to various imaging pattern shapes.

[0077] FIG. 17 shows the imaging patterns used to compare the usefulness of the spectral evaluation value V and the spectral linewidth E95. The imaging patterns shown in FIG. 17 include two types of patterns: a DENCE pattern in which multiple exposure regions are densely packed, and an ISO pattern that is located away from other exposure regions. The deviation from the reference dimension of the ISO pattern when the exposure dose is adjusted so that the dimension of the DENCE pattern is 45 nm is defined as ΔCD. The reference dimension of the ISO pattern is the dimension of the ISO pattern when the spectral linewidth E95 is 0.01 pm.

[0078] Fig. 18 is a graph showing the relationship between the spectral linewidth E95 and ΔCD in the imaging pattern of Fig. 17, and Fig. 19 is a graph showing the relationship between the spectrum evaluation value V and ΔCD in the imaging pattern of Fig. 17. For each of Fig. 18 and Fig. 19, simulations were performed using many variations including the spectral waveforms exemplified in Fig. 10 and Fig. 11, and ΔCD was plotted.

[0079] 18, two trends are observed in the ratio of the change in ΔCD to the change in the spectral linewidth E95. For this reason, even if the spectral linewidth E95 is measured, it may not be possible to accurately know the imaging performance on the wafer surface. 19, the relationship between the spectrum evaluation value V and ΔCD is approximately a straight line. Therefore, the imaging performance on the wafer surface can be known by measuring the spectrum evaluation value V. The desired imaging performance can be achieved by controlling the spectrum evaluation value V to a certain target evaluation value.

[0080] Figure 20 shows another imaging pattern used to compare the usefulness of the spectrum evaluation value V and the spectral linewidth E95. The imaging pattern shown in Figure 20 includes two types of patterns: a LINE pattern that imitates wiring, and a SPACE pattern that imitates the gap between adjacent wirings. The deviation of the SPACE pattern from the reference dimension when the exposure dose is adjusted so that the dimension of the LINE pattern is 100 nm is defined as ΔCD.

[0081] Fig. 21 is a graph showing the relationship between the spectral linewidth E95 and ΔCD in the imaging pattern of Fig. 20, and Fig. 22 is a graph showing the relationship between the spectrum evaluation value V and ΔCD in the imaging pattern of Fig. 20. For each of Fig. 21 and Fig. 22, simulations were performed using many variations including the spectral waveforms exemplified in Fig. 10 and Fig. 11, and ΔCD was plotted.

[0082] 21, two trends are observed in the ratio of the change in ΔCD to the change in the spectral linewidth E95. For this reason, even if the spectral linewidth E95 is measured, it may not be possible to accurately know the imaging performance on the wafer surface. 22, the relationship between the spectrum evaluation value V and ΔCD is approximately a straight line. Therefore, the imaging performance on the wafer surface can be known by measuring the spectrum evaluation value V. The desired imaging performance can be achieved by controlling the spectrum evaluation value V to a certain target evaluation value.

[0083] 2.4 Modification of the spectrum evaluation value V In Equation 3, the square of the wavelength deviation λ-λc from the centroid wavelength λc (λ-λc) 2 However, the present disclosure is not limited thereto. The spectrum evaluation value V may be calculated by the following Equation 4.

number

[0084] Equation 4 differs from Equation 3 in that, instead of squaring the wavelength deviation λ-λc in Equation 3, the absolute value of the wavelength deviation λ-λc is raised to the Nth power. The exponent N is a positive number. Equation 4 when the value of the exponent N is set to 2 is equivalent to Equation 3 when λs is set to 1.

[0085] Fig. 23 is a graph showing the relationship between the spectrum evaluation value V and ΔCD of Equation 4 in the imaging pattern of Fig. 17. Fig. 24 is a graph showing the relationship between the spectrum evaluation value V and ΔCD of Equation 4 in the imaging pattern of Fig. 20. In Figs. 23 and 24, simulation results when the values ​​of the exponent N in Equation 4 are set to 1, 2, and 3 are shown together with the respective regression lines. A correlation is observed between the spectrum evaluation value V and ΔCD in all cases where the value of the exponent N is set to 1, 2, and 3. By measuring such a spectrum evaluation value V, the imaging performance on the wafer surface can be known.

[0086] 23 and 24, the coefficient of determination, which indicates the goodness of fit of the regression line, is highest when the value of the power index N is 2. The value of the power index N is preferably 1.9 or more and 2.1 or less.

[0087] 2.5 Spectral Control Operation 25 is a flow chart showing the procedure of spectrum control in the embodiment. The spectrum measurement control processor 60 controls the spectrum waveform adjuster 15a using the spectrum evaluation value V and the target evaluation value Vt as follows.

[0088] In S31, the spectrum measurement control processor 60 sets a target evaluation value Vt. For example, the spectrum measurement control processor 60 receives data on the optical characteristics of the exposure apparatus 100 from the exposure apparatus 100, and sets a target evaluation value Vt calculated from the optical characteristics.

[0089] In S32, the spectrum measurement control processor 60 determines whether or not an oscillation trigger signal has been output from the laser control processor 30. If the oscillation trigger signal has not been output (S32: NO), the spectrum measurement control processor 60 waits until the oscillation trigger signal is output. If the oscillation trigger signal is output (S32: YES), laser light is output from the laser oscillator 20. The spectrum measurement control processor 60 advances the process to S33.

[0090] In S33, the spectrum measurement control processor 60 measures the spectrum evaluation value V using the laser light output from the laser oscillator 20. The process of S33 is performed according to the procedure described with reference to FIG.

[0091] In S34, the spectrum measurement control processor 60 compares the spectrum evaluation value V with the target evaluation value Vt, and determines whether the spectrum evaluation value V is within an allowable range. For example, it determines whether the absolute value of the difference between the spectrum evaluation value V and the target evaluation value Vt is smaller than an allowable error Ve.

[0092] If the spectrum evaluation value V is not within the allowable range in S34 (S34: NO), the spectrum measurement control processor 60 advances the process to S35. In S35, the spectrum measurement control processor 60 controls the spectrum waveform adjuster 15a by transmitting a control signal to drive the spectrum driver 64. For example, when the spectrum evaluation value V is larger than the target evaluation value Vt, the spectrum waveform adjuster 15a is controlled to narrow the spectral linewidth, and when the spectrum evaluation value V is smaller than the target evaluation value Vt, the spectrum waveform adjuster 15a is controlled to widen the spectral linewidth. After S35, the spectrum measurement control processor 60 returns the process to S32.

[0093] If the spectrum evaluation value V is within the allowable range in S34 (S34: YES), the spectrum measurement control processor 60 ends the process of this flowchart. After that, the laser device 1a continues to output the laser light while keeping the setting of the spectrum waveform adjuster 15a fixed. Alternatively, the spectrum measurement control processor 60 may return to the process of S32 and repeatedly measure and determine the spectrum evaluation value V while continuing to output the laser light.

[0094] 2.6 Spectral Shape Adjuster Variations 2.6.1 Configuration Figures 26 and 27 show schematic configurations of modified examples of the spectral waveform adjuster. In this modified example, the spectral waveform adjuster is made up of a line narrower 141. Figure 26 shows line narrower 141 as viewed in the -V direction, and Figure 27 shows line narrower 141 as viewed in the -H direction.

[0095] The line narrowing device 141 includes a grating system 14h instead of the grating 14c (see FIG. 2). The grating system 14h includes gratings 14i and 14j. The gratings 14i and 14j are disposed at different positions in the direction of the V axis. The direction of the grooves of each of the gratings 14i and 14j coincides with the direction of the V axis.

[0096] The gratings 14i and 14j are supported by a holder 14k. However, while the grating 14i is supported so as to maintain a constant attitude, the grating 14j can be rotated around an axis parallel to the V axis by a rotation mechanism 14m.

[0097] The line narrowing device 141 includes a beam splitting optical system 14n between the prism 14b and the grating system 14h. The beam splitting optical system 14n includes a parallel plane substrate 14o.

[0098] The parallel plane substrate 14o is disposed so as to overlap a part of the cross section of the optical path of the light beam that has passed through the prism 14b. The parallel plane substrate 14o is disposed in the optical path of the light beam between the prism 14b and the grating 14j. The parallel plane substrate 14o is supported by a holder 14p. The parallel plane substrate 14o is configured so as to be movable in a direction parallel to the V axis by a linear stage 14q.

[0099] The plane-parallel substrate 14o includes an incident surface 14r on which a part of the light beam passing through the prism 14b is incident, and an exit surface 14s on which the light incident on the plane-parallel substrate 14o through the incident surface 14r is emitted from inside the plane-parallel substrate 14o toward the grating 14j. The incident surface 14r and the exit surface 14s are both parallel to the H-axis, and the incident surface 14r and the exit surface 14s are parallel to each other. The incident surface 14r and the exit surface 14s are inclined with respect to the incident direction of the light beam so as to refract the light beam. Specifically, a normal vector 14v of the incident surface 14r is parallel to the VZ plane, and furthermore, this normal vector 14v has directional components in the -V direction and the +Z direction. The plane-parallel substrate 14o further includes an end surface 14t facing the first portion B1 of the light beam. The end surface 14t forms an acute angle with the output surface 14s. The end surface 14t may be parallel to the HZ plane.

[0100] Prism 14a is supported by holder 14f, and prism 14b is supported by holder 14g. Alternatively, prism 14b may be supported directly by rotation stage 14e without holder 14g, as in the case of FIG.

[0101] 2.6.2 Operation The first portion B1 of the light beam that has passed through the prism 14b passes through the outside of the plane-parallel substrate 14o and enters the grating 14i. The second portion B2 of the light beam passes through the inside of the plane-parallel substrate 14o and enters the grating 14j. At this time, the plane-parallel substrate 14o shifts the optical path axis of the second portion B2 of the light beam in the +V direction with respect to the optical path axis of the first portion B1. The optical path axis refers to the central axis of the optical path. In this way, the plane-parallel substrate 14o separates the first portion B1 from the second portion B2 of the light beam by transmitting a part of the light beam.

[0102] The light incident on the gratings 14i and 14j is reflected by the grooves of each of the gratings 14i and 14j and diffracted in a direction according to the wavelength of the light. As a result, the light reflected by the grooves of each of the gratings 14i and 14j is dispersed in a plane parallel to the HZ plane. The grating 14i is arranged in a Littrow configuration so that the angle of incidence of the light beam incident on the grating 14i from the prism 14b coincides with the diffraction angle of the diffracted light of the desired first wavelength. The grating 14j is arranged in a Littrow configuration so that the angle of incidence of the light beam incident on the grating 14j from the prism 14b coincides with the diffraction angle of the diffracted light of the desired second wavelength. When the angles of incidence of the light beams incident on gratings 14i and 14j from prism 14b are different from each other, a wavelength difference occurs between a first wavelength of the diffracted light returned from grating 14i to prism 14b and a second wavelength of the diffracted light returned from grating 14j to prism 14b.

[0103] 26 and 27, the dashed arrows indicating the light beams indicate only the direction from prism 14a to gratings 14i and 14j, but the light beams of the wavelengths selected by line narrowing device 141 travel from gratings 14i and 14j to prism 14a via a path opposite to that indicated by the dashed arrows.

[0104] The prisms 14a and 14b reduce the beam width of the light returned from the gratings 14i and 14j in a plane parallel to the HZ plane, and return the light to the inside of the laser chamber 10 through the window 10a (see Figures 2 and 15).

[0105] When the rotating stage 14e rotates the prism 14b slightly, the traveling direction of the light beam emitted from the prism 14b toward the gratings 14i and 14j changes slightly in a plane parallel to the HZ plane. This causes a slight change in the incidence angle of the light beam incident on the gratings 14i and 14j from the prism 14b. Therefore, both the first wavelength and the second wavelength change. When the rotation mechanism 14m rotates the grating 14j slightly, the incidence angle of the light beam incident from the prism 14b to the grating 14i does not change, but the incidence angle of the light beam incident from the prism 14b to the grating 14j changes slightly, thereby changing the wavelength difference between the first wavelength and the second wavelength.

[0106] With the above configuration and operation, the first wavelength and the second wavelength are selected from the light beam emitted from the window 10a of the laser chamber 10 and returned to the laser chamber 10. This allows the laser device 1a to output laser light including two peak wavelengths. By controlling the rotating stage 14e and the rotating mechanism 14m, the first wavelength and the second wavelength can also be set separately.

[0107] Furthermore, the linear stage 14q changes the position of the parallel flat substrate 14o in the V-axis direction, thereby changing the energy ratio between the first portion B1 and the second portion B2. By moving the plane-parallel substrate 14o in the -V direction, the second portion B2 of the light beam incident on the plane-parallel substrate 14o is increased, and the amount of light incident on the grating 14j is increased. Therefore, the energy of the second wavelength component included in the laser beam is increased. By moving the plane-parallel substrate 14o in the +V direction, the second portion B2 of the light beam incident on the plane-parallel substrate 14o is reduced, and the light incident on the grating 14j is reduced. Therefore, the energy of the second wavelength component included in the laser light is reduced.

[0108] According to this, it is possible to output laser light including two peak wavelengths as exemplified in FIG. 11 or laser light having an asymmetric spectral waveform as exemplified in FIG. 10, and control the spectral waveform of the laser light.

[0109] 2.6.3 Other configuration examples Instead of the configuration described with reference to FIGS. 26 and 27, the following configuration (1) or (2) may be adopted.

[0110] (1) Instead of replacing grating 14c (see FIG. 2) with gratings 14i and 14j arranged at different positions in the V direction, prism 14b may be replaced with a first prism and a second prism (not shown) arranged at different positions in the V direction. By making the first prism and the second prism rotatable about an axis parallel to the V axis, the first wavelength and the second wavelength can be controlled individually. By making the first prism and the second prism movable as a unit in a direction parallel to the V axis, the energy ratio between the first wavelength component and the second wavelength component can be controlled.

[0111] (2) Instead of replacing grating 14c (see FIG. 2) with gratings 14i and 14j arranged at different positions in the V direction, a first mirror and a second mirror (not shown) may be arranged at different positions in the V direction between prism 14b and grating 14c. By making the first mirror and the second mirror rotatable about an axis parallel to the V axis, the first wavelength and the second wavelength can be controlled individually. By making the first mirror and the second mirror movable as a unit in a direction parallel to the V axis, the energy ratio between the first wavelength component and the second wavelength component can be controlled.

[0112] 2.7 Effect (1) According to an embodiment of the present disclosure, a laser apparatus 1a connectable to an exposure apparatus 100 includes a spectrometer 19 that acquires an average waveform Oa from an interference pattern of laser light output from the laser apparatus 1a, and a spectrum measurement control processor 60. The spectrum measurement control processor 60 is configured to calculate an estimated spectrum waveform I(λ) indicating a relationship between wavelength λ and light intensity using the average waveform Oa, calculate a representative wavelength included in the wavelength range of the estimated spectrum waveform I(λ), and calculate a spectrum evaluation value V using a first integral value obtained by integrating, over the wavelength range, the product of a function of wavelength deviation λ-λc from the representative wavelength and the light intensity indicated by the estimated spectrum waveform I(λ). This makes it possible to appropriately evaluate the exposure performance in the exposure apparatus 100 even for laser light having a spectral waveform different from a Gaussian distribution. Furthermore, the spectral evaluation value V can be applied to various imaging pattern shapes. Therefore, it is possible to appropriately perform spectral control to realize the desired exposure performance.

[0113] (2) According to the embodiment, the spectrum measurement control processor 60 maps the average waveform Oa into a spectral space to generate a measured spectrum waveform O(λ), and calculates an estimated spectrum waveform I(λ) by deconvolving the measured spectrum waveform O(λ) with the instrument function S(λ) of the spectrometer 19. According to this, the influence of the instrument function S(λ) of the spectrometer 19 can be removed, and the exposure performance of the exposure tool 100 can be appropriately evaluated.

[0114] (3) According to the embodiment, the representative wavelength is the centroid wavelength λc of the estimated spectral waveform I(λ). According to this, even if the spectrum waveform is asymmetric in which the central wavelength and the centroid wavelength λc are different, the exposure performance of the exposure apparatus 100 can be appropriately evaluated.

[0115] (4) According to the embodiment, the spectrum measurement control processor 60 calculates the centroid wavelength λc by dividing the second integral value obtained by integrating, over the wavelength range, the product of the wavelength λ and the light intensity indicated by the estimated spectrum waveform I(λ), by a third integral value obtained by integrating, over the wavelength range, the light intensity indicated by the estimated spectrum waveform I(λ). According to this, even in the case of an asymmetric spectral waveform in which the central wavelength and the centroid wavelength λc are different, or a spectral waveform having multiple peaks, it is possible to appropriately evaluate the exposure performance of the exposure apparatus 100.

[0116] (5) According to the embodiment, the function of the wavelength deviation λ-λc is a power of the absolute value |λ-λc| of the wavelength deviation λ-λc, where N is a positive number. According to this, the spectrum evaluation value V can be used to appropriately evaluate the exposure performance in the exposure apparatus 100.

[0117] (6) According to an embodiment, the exponent N is equal to or greater than 1.9 and equal to or less than 2.1. According to this, the spectrum evaluation value V can be used to more appropriately evaluate the exposure performance in the exposure apparatus 100.

[0118] (7) According to the embodiment, the spectrum measurement control processor 60 calculates the spectrum evaluation value V by dividing the first integral value by the third integral value. According to this, by dividing by the third integral value, it is possible to evaluate the exposure performance according to the spectral waveform regardless of the light amount.

[0119] (8) According to the embodiment, the spectrum measurement control processor 60 calculates the spectrum evaluation value V by dividing the first integral value by the product of the third integral value and a constant λs obtained from a function of the wavelength λ included in the wavelength range. According to this, the dimension of the wavelength λ included in the spectrum evaluation value V can be lowered, and the exposure performance can be appropriately evaluated.

[0120] (9) According to the embodiment, there is further provided a spectral waveform adjuster 15a that adjusts the spectral waveform of the laser light incident on the spectroscope 19. The spectrum measurement control processor 60 controls the spectral waveform adjuster 15a using the result of comparison between the spectral evaluation value V and the target evaluation value Vt. According to this, the desired exposure performance can be realized by control using the spectrum evaluation value V and the target evaluation value Vt.

[0121] (10) According to an embodiment, the spectral waveform adjuster 15a is configured to adjust the spectral linewidth of the laser beam. The spectrum measurement control processor 60 controls the spectral waveform adjuster 15a to reduce the spectral linewidth when the spectral evaluation value V is greater than the target evaluation value Vt, and controls the spectral waveform adjuster 15a to increase the spectral linewidth when the spectral evaluation value V is less than the target evaluation value Vt. According to this, the spectrum evaluation value V can be made smaller by narrowing the spectral linewidth, and the spectrum evaluation value V can be made larger by widening the spectral linewidth.

[0122] 3.Other The above description is intended to be illustrative rather than restrictive. Thus, it will be apparent to one skilled in the art that modifications may be made to the disclosed embodiments without departing from the scope of the claims. It will also be apparent to one skilled in the art that the disclosed embodiments may be used in combination.

[0123] Terms used throughout the present specification and claims should be construed as "open ended" terms unless otherwise specified. For example, terms such as "include," "have," "comprise," and "include" should be construed as "not excluding the presence of elements other than those listed." In addition, the modifier "a" should be construed as meaning "at least one" or "one or more." In addition, the term "at least one of A, B, and C" should be construed as "A," "B," "C," "A+B," "A+C," "B+C," or "A+B+C." Furthermore, it should be construed to include combinations thereof with elements other than "A," "B," and "C."

Claims

1. A laser device connectable to an exposure device, comprising: a spectrometer that generates a measurement waveform from an interference pattern of the laser light output from the laser device; 1. A processor comprising: calculating a first spectral waveform indicating a relationship between wavelength and light intensity using the measured waveform; Calculating a representative wavelength included in a wavelength range of the first spectral waveform; the processor being configured to calculate an evaluation value of the first spectral waveform using a first integral value obtained by integrating, over the wavelength range, a product of a function of wavelength deviation from the representative wavelength and the light intensity; A laser device comprising:

2. 2. The laser device according to claim 1, The processor, Mapping the measured waveform into a spectral space to generate a second spectral waveform; calculating the first spectral waveform by deconvoluting the second spectral waveform with an instrument function of the spectrometer; Laser device.

3. 2. The laser device according to claim 1, The representative wavelength is a centroid wavelength of the first spectral waveform. Laser device.

4. 4. The laser device according to claim 3, The processor calculates the centroid wavelength by dividing a second integral value obtained by integrating the product of the wavelength and the light intensity over the wavelength range by a third integral value obtained by integrating the light intensity over the wavelength range. Laser device.

5. 2. The laser device according to claim 1, The function is a power of the absolute value of the wavelength deviation, the power exponent being a positive number. Laser device.

6. 6. The laser device according to claim 5, The exponent is greater than or equal to 1.9 and less than or equal to 2.

1. Laser device.

7. 2. The laser device according to claim 1, the processor calculates the evaluation value by dividing the first integral value by a third integral value obtained by integrating the light intensity with respect to the wavelength range; Laser device.

8. 2. The laser device according to claim 1, the processor calculates the evaluation value by dividing the first integral value by a product of a third integral value obtained by integrating the light intensity with respect to the wavelength range and a function of the wavelength included in the wavelength range; Laser device.

9. 2. The laser device according to claim 1, a spectral waveform adjuster for adjusting the spectral waveform of the laser light incident on the spectrometer, The processor controls the spectral waveform adjuster using a comparison result between the evaluation value and a target evaluation value. Laser device.

10. 10. The laser device of claim 9, the spectral waveform adjuster is configured to adjust a spectral linewidth of the laser light; the processor controls the spectral waveform adjuster to narrow the spectral linewidth when the evaluation value is greater than the target evaluation value, and controls the spectral waveform adjuster to widen the spectral linewidth when the evaluation value is less than the target evaluation value. Laser device.

11. A measurement waveform is generated from an interference pattern of laser light output from a laser device connectable to an exposure device; calculating a first spectral waveform indicating a relationship between wavelength and light intensity using the measured waveform; Calculating a representative wavelength included in a wavelength range of the first spectral waveform; Calculating an evaluation value of the first spectral waveform using a first integral value obtained by integrating the product of a function of the wavelength deviation from the representative wavelength and the light intensity over the wavelength range.

4. A method for evaluating a spectrum of laser light, comprising:

12. The evaluation method according to claim 11, Mapping the measured waveform into a spectral space to generate a second spectral waveform; calculating the first spectral waveform by deconvoluting the second spectral waveform with an instrument function of a spectrometer that generated the measured waveform; Evaluation method.

13. The evaluation method according to claim 11, The representative wavelength is a centroid wavelength of the first spectral waveform. Evaluation method.

14. The evaluation method according to claim 13, calculating the centroid wavelength by dividing a second integral value obtained by integrating the product of the wavelength and the light intensity over the wavelength range by a third integral value obtained by integrating the light intensity over the wavelength range; Evaluation method.

15. The evaluation method according to claim 11, The function is a power of the absolute value of the wavelength deviation, the power exponent being a positive number. Evaluation method.

16. The evaluation method according to claim 15, The exponent is greater than or equal to 1.9 and less than or equal to 2.

1. Evaluation method.

17. The evaluation method according to claim 11, calculating the evaluation value by dividing the first integral value by a third integral value obtained by integrating the light intensity with respect to the wavelength range; Evaluation method.

18. The evaluation method according to claim 11, calculating the evaluation value by dividing the first integral value by a product of a third integral value obtained by integrating the light intensity with respect to the wavelength range and a function of the wavelength included in the wavelength range; Evaluation method.

19. The evaluation method according to claim 11, adjusting a spectral waveform of the laser beam using a comparison result between the evaluation value and a target evaluation value; Evaluation method.

20. 1. A method for manufacturing an electronic device, comprising: a spectrometer that generates a measurement waveform from an interference pattern of a laser beam output from a laser device that can be connected to an exposure device; 1. A processor comprising: calculating a first spectral waveform indicating a relationship between wavelength and light intensity using the measured waveform; Calculating a representative wavelength included in a wavelength range of the first spectral waveform; the processor being configured to calculate an evaluation value of the first spectral waveform using a first integral value obtained by integrating, over the wavelength range, a product of a function of wavelength deviation from the representative wavelength and the light intensity; The laser light is generated by the laser device comprising: outputting the laser light to the exposure device; In order to manufacture the electronic device, the laser light is exposed onto a photosensitive substrate in the exposure apparatus. A method for manufacturing an electronic device, comprising:

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