Laser device, pulse width extension device, and method for manufacturing electronic device

Abstract

A laser device of one aspect of the present disclosure has a laser oscillator that outputs pulsed laser light, and a first optical pulse stretcher, a second optical pulse stretcher, and a third optical pulse stretcher that are arranged on an optical path of the pulsed laser light. In a case where an optical path length of a delay optical path of the first optical pulse stretcher is L1, an optical path length of a delay optical path of the second optical pulse stretcher is L2, an optical path length of a delay optical path of the third optical pulse stretcher is L3, and n is an integer of 2 or more, L2 is an integer of 2 or more times L1, and L3 satisfies (n-0.75) x L1 ≤ L3 ≤ (n-0.25) x L1.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a laser device, a pulse width expansion device, and a manufacturing method of an electronic device. BACKGROUND

[0002] In recent years, in a semiconductor exposure device, with miniaturization and high integration of a semiconductor integrated circuit, improvement of resolution is required. Therefore, shortening of a wavelength of light emitted from an exposure light source is developed. For example, as a gas laser device for exposure, a KrF excimer laser device which outputs laser light of a wavelength of about 248 nm, and an ArF excimer laser device which outputs laser light of a wavelength of about 193 nm are used.

[0003] The spectral line width of natural oscillation light of the KrF excimer laser device and the ArF excimer laser device is wide, about 350 to 400 pm. Therefore, when a projection lens is configured using a material which transmits ultraviolet rays such as KrF and ArF laser light, chromatic aberration is sometimes generated. As a result, resolution can be reduced. Therefore, it is necessary to narrow the spectral line width of laser light output from the gas laser device to a degree at which chromatic aberration can be ignored. Therefore, in the laser resonator of the gas laser device, in order to narrow the spectral line width, a line narrow module (LNM) including a narrow band element (etalon, grating, or the like) is sometimes provided. Hereinafter, the gas laser device of which the spectral line width is narrowed is referred to as a narrow band gas laser device.

[0004] PRIOR ART DOCUMENTS

[0005] PATENT DOCUMENTS

[0006] Patent Document 1: U.S. Patent No. 5309456

[0007] Patent Document 2: U.S. Patent No. 6238063 SUMMARY

[0008] A laser device of one aspect of the present disclosure includes: a laser oscillator which outputs pulsed laser light; a first optical pulse stretcher which is disposed on an optical path of the pulsed laser light; a second optical pulse stretcher which is disposed on the optical path of the pulsed laser light; and a third optical pulse stretcher which is disposed on the optical path of the pulsed laser light, in a case where an optical path length of a delay optical path of the first optical pulse stretcher is L1, an optical path length of a delay optical path of the second optical pulse stretcher is L2, an optical path length of a delay optical path of the third optical pulse stretcher is L3, and n is an integer of 2 or more, L2 is an integer of 2 or more times L1, and L3 satisfies (n-0.75) x L1 ≤ L3 ≤ (n-0.25) x L1.

[0009] The pulse width expansion device of another aspect of the present disclosure expands the pulse width of a pulsed laser, wherein the pulse width expansion device includes a first optical pulse stretcher, a second optical pulse stretcher, and a third optical pulse stretcher configured on an optical path of the pulsed laser, in a case where an optical path length of a delay optical path of the first optical pulse stretcher is L1, an optical path length of a delay optical path of the second optical pulse stretcher is L2, an optical path length of a delay optical path of the third optical pulse stretcher is L3, and n is an integer of 2 or more, L2 is an integer of 2 or more times L1, and L3 satisfies (n-0.75) x L1 ≤ L3 ≤ (n-0.25) x L1.

[0010] The manufacturing method of an electronic device of another aspect of the present disclosure includes the following steps: generating a laser whose pulse width is expanded by a laser device; outputting the laser to an exposure device or a laser irradiation device; and exposing the laser on a photosensitive substrate in the exposure device or irradiating the laser on an irradiation object in the laser irradiation device to manufacture an electronic device, the laser device including: a laser oscillator that outputs a pulsed laser; a first optical pulse stretcher configured on an optical path of the pulsed laser; a second optical pulse stretcher configured on the optical path of the pulsed laser; and a third optical pulse stretcher configured on the optical path of the pulsed laser, in a case where an optical path length of a delay optical path of the first optical pulse stretcher is L1, an optical path length of a delay optical path of the second optical pulse stretcher is L2, an optical path length of a delay optical path of the third optical pulse stretcher is L3, and n is an integer of 2 or more, L2 is an integer of 2 or more times L1, and L3 satisfies (n-0.75) x L1 ≤ L3 ≤ (n-0.25) x L1. BRIEF DESCRIPTION OF DRAWINGS

[0011] Hereinafter, several embodiments of the present disclosure will be described as simple examples with reference to the drawings.

[0012] Figure 1 is a graph for explaining a spectral line width.

[0013] Figure 2 is a graph for explaining the definition of E95.

[0014] Figure 3 is a graph showing an example of a speckle image obtained by imaging a pattern composed of bright and dark spots.

[0015] Figure 4 is a graph showing Figure 3 is a graph showing a histogram of the bright and dark of the speckle image shown in FIG.

[0016] Figure 5 A structure example of the excimer laser device of the comparative example is schematically shown.

[0017] Figure 6A pulse waveform of the pulse laser output from the excimer laser device of the comparative example is illustrated as an example.

[0018] Figure 7 A structure of the excimer laser device of Embodiment 1 is schematically illustrated.

[0019] Figure 8 is a graph showing a setting example of the optical path lengths L1, L2, L3 of the 1st OPS, the 2nd OPS, and the 3rd OPS, respectively.

[0020] Figure 9 A pulse waveform obtained in a case where the OPS system of Comparative Example 1 shown in Figure 8

[0021] Figure 10 A pulse waveform obtained in a case where the OPS system of Embodiment B shown in Figure 8

[0022] Figure 11 is a graph showing a change of TIS / (L2+L3) with respect to the optical path length coefficient.

[0023] Figure 12 A structure of the excimer laser device of Embodiment 2 is schematically illustrated.

[0024] Figure 13 is a graph showing a setting example of the optical path lengths L1, L2, L3, L4 of the 1st OPS, the 2nd OPS, the 3rd OPS, and the 4th OPS, respectively.

[0025] Figure 14 A pulse waveform obtained in a case where the OPS system of Comparative Example 2 shown in

[0026] Figure 15 A pulse waveform obtained in a case where the OPS system of Embodiment G shown in

[0027] Figure 16 is a graph showing a change of TIS / (L3+L4) with respect to the optical path length coefficient.

[0028] Figure 17 A structure example of a laser irradiation system of an excimer laser device to which free oscillation is applied is schematically illustrated.

[0029] Figure 18 A structure example of an excimer laser device including a wavelength-variable solid laser system as a master oscillator is schematically illustrated.

[0030] Figure 19 A structure example of an exposure apparatus is schematically illustrated. DETAILED DESCRIPTION ​​

[0031] - TABLE OF CONTENTS -

[0032] 1. Explanation of terms

[0033] 1.1 Definition of E95

[0034] 1.2 Definition of coherence length

[0035] 1.3 Definition of speckle contrast

[0036] 1.4 Definition of TIS pulse time width

[0037] 2. Summary of laser device of comparative example

[0038] 2.1 Configuration

[0039] 2.2 Operation

[0040] 2.3 Problem

[0041] 3. Embodiment 1

[0042] 3.1 Configuration

[0043] 3.2 Operation

[0044] 3.3 Effects / advantages

[0045] 3.4 Others

[0046] 4. Embodiment 2

[0047] 4.1 Configuration

[0048] 4.2 Operation

[0049] 4.3 Effects / advantages

[0050] 4.4 Others

[0051] 5. Variations of laser device

[0052] 5.1 Free-running excimer laser device

[0053] 5.1.1 Configuration

[0054] 5.1.2 Operation

[0055] 5.1.3 Effects / advantages

[0056] 5.2 Excimer laser device containing a solid-state laser system as master oscillator

[0057] 5.2.1 Configuration

[0058] 5.2.2 Operation

[0059] 5.2.3 Variations

[0060] 6. Hardware Structure of Various Control Units

[0061] 7. Manufacturing Method of Electronic Devices

[0062] 8. Others

[0063] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. The embodiments described below show several examples of the present disclosure and do not limit the content of the present disclosure. In addition, the structures and operations described in each embodiment are not necessarily all essential to the structures and operations of the present disclosure. In addition, the same reference numerals are assigned to the same structural elements and repeated descriptions are omitted.

[0064] 1. Explanation of Terms <C

[0065] 1.1 Definition of E95

[0066] The spectral line width refers to Figure 1 the full width at the optical power threshold of the spectral waveform of the laser shown. In this specification, the relative value of each optical power threshold with respect to the optical power peak is referred to as the line width threshold Thresh (0 < Thresh < 1). For example, the half value of the peak is referred to as the line width threshold 0.5. In particular, the full width W / 2 of the spectral waveform with the line width threshold 0.5 is referred to as the full width at half maximum or FWHM (Full Width at Half Maximum).

[0067] As Figure 2 shown, the spectral purity, for example, 95% purity E95 refers to the full width W95% of the part occupying 95% centered on the wavelength λ0 in all spectral energies, and the following formula (1) holds. <000016 <C

[0068] [Mathematical Formula 1]

[0069] <C

[0070] In addition, in this specification, unless otherwise specifically stated, the spectral purity is assumed to be E95 for explanation.

[0071] 1.2 Definition of Coherence Length

[0072] When the center wavelength of the laser is λ0 and the spectral line width is Δλ, the coherence length of the laser can be expressed by the following formula (2).

[0073] [Mathematical Formula 2]

[0074] [<C

[0075] 1.3 Definition of Speckle Contrast

[0076] Speckle refers to bright and dark spots generated when laser light is scattered in a random medium. Figure 3 is a drawing illustrating an example of a speckle image obtained by imaging a pattern composed of bright and dark spots. Furthermore, Figure 4 is a drawing illustrating Figure 3 is a drawing illustrating a histogram of bright and dark of the speckle image illustrated in FIG. 8.

[0077] As a speckle evaluation index, speckle contrast SC is generally used. In a case where a standard deviation of intensity of a speckle image is σ and an average of intensity of the speckle image is I, the speckle contrast SC can be expressed by the following formula (3).

[0078] [Mathematical Formula 3]

[0079]

[0080] In expanding the pulse width of the extended pulse laser, the coherence is reduced, and the speckle contrast SC is reduced.

[0081] 1.4 Definition of TIS pulse time width

[0082] As one of the indices indicating the pulse time width of the laser, TIS pulse time width is used.

[0083] TIS pulse time width ΔT TIS is defined by the following formula (4).

[0084] [Mathematical Formula 4]

[0085]

[0086] Here, t is time. I(t) is the light intensity at time t. In the present specification, "TIS width" refers to TIS pulse time width.

[0087] 2. Outline of laser device of comparative example

[0088] 2.1 Structure

[0089] Figure 5 The structure example of the excimer laser device 10 of the comparative example is schematically illustrated. The comparative example of the present disclosure is a way that the applicant recognizes as known only to the applicant, and is not a publicly known example that the applicant himself acknowledges.

[0090] The excimer laser device 10 includes an oscillator 12, an optical pulse stretcher (OPS) system 14, a monitor module 16, a shutter 18, and a laser control section 20. The OPS system 14 includes a first OPS 100 and a second OPS 200. The first OPS 100, the second OPS 200, the monitor module 16, and the shutter 18 are arranged in this order on an optical path of a pulsed laser light output from the oscillator 12.

[0091] When the optical path length of the delay optical path of the first OPS 100 is denoted by LI and the optical path length of the delay optical path of the second OPS 200 is denoted by L2, the optical path length L2 of the delay optical path of the second OPS 200 is set to an integral multiple of 2 or more with respect to LI. For example, the optical path length L2 is set to a length of 2 times LI.

[0092] The oscillator 12 includes a cavity 120, a charger 122, a pulse power module (PPM) 124, a narrowbanding device 126, and an output coupling mirror 128.

[0093] The narrowbanding device 126 includes a prism expander, which is not shown, and a grating, which is not shown. The prism expander and the grating are configured in a Littrow configuration in which an incident angle and a diffraction angle coincide.

[0094] The output coupling mirror 128 is a mirror having a reflectance of 40% to 60%. The output coupling mirror 128 and the narrowbanding device 126 constitute an optical resonator. The cavity 120 is arranged on an optical path of the optical resonator.

[0095] The cavity 120 includes a pair of electrodes 130a, 130b, an insulating member 132, a front side window 134, and a rear side window 136. A laser gas of ArF or KrF or XeCl or XeF is housed in the cavity 120.

[0096] The electrode 130a is connected to an output terminal of a high voltage of the PPM 124 via the insulating member 132. The electrode 130b is connected to a ground. The electrodes 130a, 130b are arranged so as to have a prescribed gap interval. The electrodes 130a, 130b are discharge electrodes, and a space between the electrodes 130a, 130b becomes a discharge space (discharge region).

[0097] The front side window 134 and the rear side window 136 are arranged so as to transmit a laser light generated in the discharge space.

[0098] The PPM 124 includes a switch 125 and a charging capacitor, which is not shown. The switch 125 is connected to a signal line that transmits an ON signal of the switch 125 from the laser control section 20.

[0099] The charger 122 is connected to the charging capacitor of the PPM 124. The charger 122 receives data of the charging voltage from the laser control section 20, and charges the charging capacitor of the PPM 124.

[0100] The first OPS 100 includes a beam splitter BS1 and four concave mirrors 101 to 104. The beam splitter BS1 is disposed on the optical path of the pulsed laser light output from the oscillator 12. The beam splitter BS1 is coated with a film that reflects a part of the incident pulsed laser light and transmits another part. The reflectance of the beam splitter BS1 is preferably 40% to 70%, and more preferably about 60%.

[0101] The concave mirrors 101 to 104 constitute a delay optical path of the pulsed laser light reflected at the first face of the beam splitter BS1. The concave mirrors 101 to 104 are each a concave mirror having a focal length of substantially the same f1.

[0102] The concave mirror 101 and the concave mirror 102 are disposed so that the pulsed laser light reflected at the first face of the beam splitter BS1 is reflected at the concave mirror 101 and incident on the concave mirror 102. The concave mirror 103 and the concave mirror 104 are disposed so that the pulsed laser light reflected at the concave mirror 102 is reflected at the concave mirror 103 and incident on the concave mirror 104. The concave mirror 104 is disposed so that the pulsed laser light reflected at the concave mirror 104 is incident on the second face of the beam splitter BS1 opposite the first face.

[0103] The concave mirror 101 and the concave mirror 102 are disposed so that the pulsed laser light reflected at the first face of the beam splitter BS1 is imaged as a first image that inverts the image in the first face of the beam splitter BS1. The concave mirror 103 and the concave mirror 104 are disposed so that the first image is returned to the beam splitter BS1 and imaged as a second image by being righted at the second face of the beam splitter BS1. In this case, the optical path length LI of the delay optical path of the first OPS 100 becomes LI = 8 x f1. The optical path length LI refers to one-turn delay optical path length of the delay optical path of the first OPS 100. As an example, the optical path length LI of the first OPS 100 is 7 m.

[0104] The beam splitter BS1 is disposed so that the pulsed laser light that is not reflected at the first face of the beam splitter BS1 but transmitted is incident on the second OPS 200.

[0105] The second OPS 200 is disposed on the optical path of the pulsed laser light output from the first OPS 100. The second OPS 200 includes a beam splitter BS2 and concave mirrors 201 to 204. The beam splitter BS2 can be the same structure as the beam splitter BS1. The concave mirrors 201 to 204 are each a concave mirror having a focal length of substantially the same f2. The focal length f2 is a longer focal length than the focal length f1.

[0106] The beam splitter BS2 and the concave mirrors 201 to 204 in the second OPS 200 are configured in the same configuration relationship as the beam splitter BS1 and the concave mirrors 101 to 104 in the first OPS 100. In this case, the optical path length L2 of the delay optical path of the second OPS 200 becomes L2 = 8 x f2. The optical path length L2 refers to one round of the delay optical path length of the delay optical path of the second OPS 200. As an example, the optical path length L2 of the second OPS 200 is 14 m.

[0107] The monitor module 16 is disposed on the optical path of the pulsed laser light output from the OPS system 14. The monitor module 16 includes a beam splitter 162 and a light sensor 164. The light sensor 164 is connected to the laser control section 20, and the detection data of the light sensor 164 is transmitted to the laser control section 20. The shutter 18 is disposed on the optical path of the pulsed laser light after passing through the monitor module 16. The shutter 18 is connected to the laser control section 20 via a signal line that transmits a signal for opening and closing the shutter.

[0108] The pulsed laser light output from the excimer laser device 10 is input to the exposure device 80. The laser control section 20 is connected to an exposure control section 82 of the exposure device 80. The signal line between the laser control section 20 and the exposure control section 82 includes a signal line for the light emission trigger signal Tr, a signal line for the data of the target pulse energy Et, and a signal line for transmitting and receiving other signals. In addition, an amplifier including a laser cavity not shown can be disposed between the oscillator 12 and the OPS system 14.

[0109] 2.2 Action

[0110] After the laser control section 20 receives the target pulse energy Et and the oscillator preparation signal from the exposure control section 82, the laser control section 20 outputs a signal to close the shutter 18, and closes the exit port of the excimer laser device 10. The laser control section 20 applies a high voltage between the electrodes 130a, 130b of the oscillator 12 when the switch 125 of the PPM 124 is turned on at a predetermined repetition frequency in synchronization with the light emission trigger signal Tr.

[0111] When the dielectric breakdown occurs between the electrodes 130a, 130b, discharge occurs between the electrodes 130a, 130b, and the laser gas is excited. As a result, laser oscillation occurs using the optical resonator composed of the narrowbanding device 126 and the output coupling mirror 128, and the pulsed laser light that is narrowbanded is output from the output coupling mirror 128.

[0112] The pulsed laser light output from the output coupling mirror 128 is incident on the OPS system 14. The pulsed laser light incident on the OPS system 14 is incident on the first face of the beam splitter BS1 of the first OPS 100. A part of the pulsed laser light incident on the first face of the beam splitter BS1 transmits through the beam splitter BS1, and is output from the first OPS 100 as 0-circulation pulsed laser light that does not circulate in the delay optical path.

[0113] The pulse laser, which is incident to the first face of the beam splitter BS1 and is reflected by the first face, enters the delay optical path of the first OPS 100 and is reflected by the concave mirror 101 and the concave mirror 102. The light image of the pulse laser reflected by the first face of the beam splitter BS1 is imaged as the first transfer image by the concave mirror 101 and the concave mirror 102. Then, the first transfer image is imaged as the second transfer image by the concave mirror 103 and the concave mirror 104 on the second face of the beam splitter BS1.

[0114] A part of the pulse laser, which is incident to the second face of the beam splitter BS1 from the concave mirror 104, is reflected by the second face of the beam splitter BS1 and is output from the first OPS 100 as the one-encircling pulse laser which encircles one time in the delay optical path of the first OPS 100. The one-encircling pulse laser is output with a delay time Δtl from the zero-encircling pulse laser. When the speed of light is c, the Δtl can be expressed as Δtl = Ll / c.

[0115] The pulse laser, which is incident to the second face of the beam splitter BS1 as the second transfer image, further enters the delay optical path of the first OPS 100 after being transmitted through the beam splitter BS1, is reflected by the concave mirrors 101 to 104, and is incident to the second face of the beam splitter BS1 again. Then, the pulse laser reflected by the second face of the beam splitter BS1 is output from the first OPS 100 as the two-encircling pulse laser which encircles two times in the delay optical path. The two-encircling pulse laser is output with a delay time Δtl from the one-encircling pulse laser.

[0116] Then, the encircling of the light in the delay optical path is repeated, whereby the three-encircling, four-encircling, five-encircling, and the like pulse lasers are output from the first OPS 100. The more the number of encircling of the pulse laser in the delay optical path, the more the light intensity is reduced.

[0117] The pulse lasers, which encircle in the delay optical path of the first OPS 100, are synthesized and output with an integer multiple of the delay time Δtl from the zero-encircling pulse laser, whereby the pulse waveforms of the respective encircling pulse lasers are overlapped. As a result, the pulse width is expanded.

[0118] Similarly, the pulse width of the pulse laser output from the first OPS 100 is expanded by the second OPS 200.

[0119] Thus, the pulse laser output from the output coupling mirror 128 of the oscillator 12 is passed through the respective delay optical paths of the first OPS 100 and the second OPS 200 a plurality of times, whereby the pulse width of the pulse laser is expanded.

[0120] A part of the pulsed laser light after the 1st OPS 100 and the 2nd OPS 200 is reflected by the beam splitter 162 to be incident on the light sensor 164. The light sensor 164 measures the pulse energy E of the incident pulsed laser light. Data representing the measurement result is sent from the light sensor 164 to the laser control section 20.

[0121] The laser control section 20 sets the charger 122 so that the difference ΔE between the target pulse energy Et and the measured pulse energy E approaches 0.

[0122] The laser control section 20 sends the oscillation preparation completion signal to the exposure control section 82 after ΔE enters the allowable range, and opens the shutter 18. The laser control section 20 turns on the switch 125 of the PPM 124 in synchronization with the light emission trigger signal Tr from the exposure control section 82, whereby pulsed laser light is output from the oscillator 12, pulse-expanded by the OPS system 14, and pulsed laser light of a pulse energy close to the target pulse energy Et is output from the excimer laser device 10.

[0123] The pulsed laser light output from the excimer laser device 10 is incident on the exposure device 80 to irradiate the resist of an unillustrated semiconductor wafer or the like with pulsed laser light.

[0124] 2.3 Problem

[0125] The speckle contrast has a correlation with the pulse width and the coherence length of the pulsed laser light, and the speckle contrast decreases when the pulse width of the pulsed laser light is expanded. In order to expand the pulse width for the purpose of reducing the speckle contrast, it is necessary to add an OPS to the optical path. It is known from Patent Literature 1 (U.S. Patent No. 5309456) or the like that the pulse width is greatly expanded. Further, it is known from Patent Literature 2 (U.S. Patent No. 6238063) or the like that three or more OPSs are connected in the optical path.

[0126] However, the optimal combination condition of the optical path lengths of the delay optical paths in the case where three or more OPSs are arranged in series in the optical path is unknown.

[0127] Figure 6 The pulse waveform of the pulsed laser light output from the excimer laser device 10 of the comparative example is exemplarily shown. In Figure 6 In the comparative example, an example in which the optical path length LI of the 1st OPS 100 is 7 m and the optical path length L2 of the 2nd OPS 200 is 14 m is shown. The delay time in one round of the 7-m delay optical path is about 23.3 ns. The optical path length L2 of the 2nd OPS 200 is set to an integral multiple of LI, specifically, an integral multiple of 2 or more, so that the peak of the pulse waveform overlaps the peak of the 1st OPS 100.

[0128] Regarding the structure of the excimer laser device 10 having such an OPS system 14, when further adding an OPS to the OPS system 14 in order to further extend the pulse width, it is preferable to extend the pulse width efficiently by adding a relatively short delay optical path length.

[0129] 3. Implementation Method 1

[0130] 3.1 Structure

[0131] Figure 7 The structure of the excimer laser device 10A according to Embodiment 1 is shown in outline. Regarding... Figure 7 The excimer laser device 10A shown is for use with Figure 5 The differences in the structure shown will be explained. The excimer laser device 10A of Embodiment 1 is used instead. Figure 5 The OPS system 14 shown has an OPS system 14A that includes a third OPS 300.

[0132] The structure of OPS100 and OPS200 Figure 5 The structure shown is the same. The third OPS300 is configured in the optical path between the second OPS200 and the monitor module 16. That is, the first OPS100, the second OPS200 and the third OPS300 are configured in series in the optical path of the pulsed laser.

[0133] The excimer laser device 10A is an example of a "laser device" in this disclosure. The oscillator 12 is an example of a "laser oscillator" in this disclosure. The OPS system 14A is an example of a "pulse width extension device" in this disclosure. The first OPS 100 is an example of a "first optical pulse stretcher" in this disclosure. The second OPS 200 is an example of a "second optical pulse stretcher" in this disclosure. The third OPS 300 is an example of a "third optical pulse stretcher" in this disclosure.

[0134] The third OPS300 includes a beam splitter BS3 and concave mirrors 301-304. The beam splitter BS3 is positioned in the optical path of the pulsed laser and is coated with a film that partially reflects and partially transmits the pulsed laser light. Preferably, the reflectivity of the beam splitter BS3 is approximately 60%.

[0135] Concave mirrors 301 to 304 are all concave mirrors with approximately the same focal length f3. Focal length f3 is longer than focal length f1. Beam splitter BS3 and concave mirrors 301 to 304 are configured in the same way as beam splitter BS1 and concave mirrors 101 to 104 in the first OPS 100. In this case, the optical path length L3 of the delay optical path in the third OPS 300 becomes L3 = 8 × f3. The optical path length L3 refers to the length of one full turn of the delay optical path in the third OPS 300.

[0136] In a configuration including three stages of OPSs of the first OPS 100, the second OPS 200, and the third OPS 300, with respect to an optical path length LI of the first OPS 100 having the shortest optical path length among them, an optical path length L3 of the third OPS to be added is set to a value offset from an integer multiple of LI. Specifically, when the optical path length of the first OPS 100 is set to LI, the optical path length L3 of the delay optical path of the third OPS 300 is set to satisfy a condition represented by the following formula (5).

[0137] [Condition 1]

[0138] (n - 0.75) x LI ≤ L3 ≤ (n - 0.25) x LI (5)

[0139] n in formula (5) is an integer of 2 or more. For example, n = 5.

[0140] It is further preferable that the optical path length L3 satisfy formula (6).

[0141] (n - 0.65) x LI ≤ L3 ≤ (n - 0.35) x LI (6)

[0142] 3.2 Operation

[0143] Next, an example in which the optical path lengths of the OPS system 14A are set in a manner satisfying Condition 1 will be described. As described above, in a case where the optical path length LI of the first OPS 100 is 7 m, the delay time in a case where the pulse is made to travel around the first OPS 100 once is approximately 23.3 ns. Here, the reason why the optical path length LI of the first OPS 100 is set to 7 m is as follows. That is, the pulse width of the pulse laser output from the oscillator 12 is approximately 40 ns. With respect to this pulse laser, in order to expand the pulse width efficiently using an OPS having the shortest optical path length possible at one stage, the optical path length LI is set so that the delay time in a case where the pulse is made to travel around the first OPS 100 once becomes 23.3 ns, which is approximately half of 40 ns.

[0144] The optical path length L2 of the second OPS is set so that the peak of the pulse waveform of the pulse that has passed through the delay optical path of the second OPS 200 overlaps with the peak of the pulse waveform of the pulse that has come out of the first OPS 100. That is, L2 is set to an integer multiple of 2 or more of LI. The description of "integer multiple" here is not limited to a strict integer multiple, but can be a substantially integer multiple, and for example, can include a tolerance range of ±0.25 with respect to a certain integer.

[0145] As an example of the optical path length L2 of the 2nd OPS 200, L2 = 12.25 m to 15.75 m (40.8 ns to 52.4 ns) is set so that the delay time in the case of one round of the delay optical path around the 2nd OPS 200 becomes approximately 23.3 x 2 = 46.6 ns.

[0146] The optical path length L3 of the delay optical path of the 3rd OPS is set so that the peak of the pulse waveform fills the valley between the peaks of the 1st OPS. That is, L3 is set to "an integer of 2 or more + 0.5" times L1. The description of "0.5 times" here is not limited to exactly 0.5 times, but can be approximately 0.5 times, for example, and can include a tolerance range of ±0.25 from 0.5. As an example of the optical path length L3 of the 3rd OPS 300, L3 = 29.75 m to 33.25 m (99.0 ns to 110.7 ns) is set so that the delay time in the case of one round of the 3rd OPS 300 becomes approximately 23.3 x 4.5 = 104.9 ns.

[0147] Figure 8 is a graph showing an example of the setting of the optical path lengths L1, L2, L3 of the 1st OPS 100, the 2nd OPS 200, and the 3rd OPS 300. Here, the pulse width (TIS width) achieved in the case where the optical path length L1 and the optical path length L2 are fixed at 7 m and 14 m, respectively, and the optical path length L3 is changed is shown.

[0148] Figure 8 "Comparative Example 1" in is set to an integer multiple (here, 5 times) of L1. In Comparative Example 1, the pulse width becomes 298.1 ns, and TIS / (L2+L3) is 6.08. The value of TIS / (L2+L3) indicates the increase ratio of the pulse width with respect to the increase amount of the optical path length of the delay optical path, and is an index indicating the efficiency of the OPS. The larger the value of TIS / (L2+L3) is, the more efficiently the pulse width can be expanded.

[0149] Examples A to E are examples in the case where the optical path length L3 is set according to Condition 1 of Formula (5). Example A is an example of L3 = 33.25 m = 5 x L1 - 0.25 x L1. Example A can achieve a larger pulse width with a shorter optical path length than Comparative Example 1.

[0150] Example B is an example of L3 = 32.55 m = 5 x L1 - 0.35 x L1. Example B is a more preferable structure than Example A, and can achieve a larger pulse width with a shorter optical path length than Example A.

[0151] Figure 9A pulse waveform obtained in a case where the OPS system of Comparative Example 1 is used is shown. Figure 10 A pulse waveform obtained in a case where the OPS system 14A of Embodiment B is used is shown. As is apparent from these drawings, according to Embodiment B, the difference between the peak and the valley of the pulse is smaller than that of Comparative Example 1, and the pulse width can be efficiently expanded with a shorter optical path length than that of Comparative Example 1.

[0152] Figure 8 The embodiment of Embodiments A to E in which TIS / (L2+L3) is the largest is Embodiment D. Embodiment D has a larger pulse width and a larger TIS / (L2+L3) than Comparative Example 1.

[0153] Embodiment E has a slightly smaller pulse width than Comparative Example 1, but has a larger TIS / (L2+L3), and can efficiently expand the pulse width.

[0154] The optical path length L3 can be expressed as L3 = n x L1 - k x L1 = (n - k) x L1 using an integer n of 2 or more and an optical path length coefficient k. k is a value satisfying 0 < k < 1. Comparative Example 1 is a case where k = 0, and Embodiment B is a case where k = 0.35.

[0155] Figure 11 is a graph showing the change of TIS / (L2+L3) with respect to the optical path length coefficient. The horizontal axis represents the optical path length coefficient, and the vertical axis represents TIS / (L2+L3). In Figure 11 , the optical path length coefficient and TIS / (L2+L3) of each of Comparative Example 1 and Embodiments A to E are plotted. As is apparent from Figure 11 , from the viewpoint of efficiently expanding the pulse width with the shortest possible optical path length, it is preferable that the optical path length coefficient k satisfy 0.25 < k < 0.75, more preferably 0.35 < k < 0.65, and particularly preferably 0.5 < k < 0.65.

[0156] 3.3 Action / Effect

[0157] According to the OPS system 14A of Embodiment 1, the pulse width can be efficiently expanded with a relatively short optical path length. Furthermore, according to the excimer laser device 10A having the OPS system 14A, TIS / (L2+L3) is larger than in a configuration having the OPS system of Comparative Example 1.

[0158] According to the excimer laser device 10A, laser light having a pulse width that is expanded can be generated, and speckle can be reduced.

[0159] 3.4 Other

[0160] The arrangement order of the 1st OPS 100, the 2nd OPS 200, and the 3rd OPS 300 on the optical path of the pulsed laser is not limited to Figure 7 The example can be appropriately exchanged. If the combination of the values of the optical path lengths L1, L2, and L3 is the same, equivalent pulse widths are achieved regardless of the arrangement order of the 1st OPS 100, the 2nd OPS 200, and the 3rd OPS 300 on the optical path.

[0161] Further, in Figure 7 , an example in which the 1st OPS 100, the 2nd OPS 200, and the 3rd OPS 300 are each formed using four concave mirrors to form a delay optical path is shown, but the structure of the OPS is not limited to this example. The OPS can be configured to include five or more concave mirrors, and for example, can be configured to include six or more concave mirrors. Further, the OPS can be configured to include mirrors other than concave mirrors.

[0162] 4. Embodiment 2

[0163] 4.1 Structure

[0164] Figure 12 The structure of the excimer laser device 10B of Embodiment 2 is schematically shown. Regarding the structure shown in Figure 12 , differences from the excimer laser device 10A shown in Figure 7 will be described. Figure 12 The excimer laser device 10B shown in Figure 7 has an OPS system 14B including a 4th OPS 400 instead of the OPS system 14A in Figure 7 . The 1st OPS 100, the 2nd OPS 200, the 3rd OPS 300, and the 4th OPS 400 are arranged in series on the optical path of the pulsed laser. The other structures can be the same as those of the excimer laser device 10A shown in

[0165] The 4th OPS 400 is arranged on the optical path between the 3rd OPS 300 and the monitor module 16. The 4th OPS 400 includes a beam splitter BS4 and concave mirrors 401 to 404.

[0166] The beam splitter BS4 can be the same structure as the beam splitter BS1. The concave mirrors 401 to 404 are each a concave mirror having a focal length of substantially the same f4. The focal length f4 is a longer focal length than the focal length f1.

[0167] The beam splitter BS4 and the concave mirrors 401 to 404 in the 4th OPS 400 are configured in the same configuration relationship as the beam splitter BS1 and the concave mirrors 101 to 104 in the 1st OPS 100. In this case, the optical path length L4 of the delay optical path of the 4th OPS 400 becomes L4 = 8 x f4. The optical path length L4 refers to one round of the delay optical path length of the 4th OPS 400.

[0168] In the case of a structure including 4-stage OPSes including the 1st OPS 100, the 2nd OPS 200, the 3rd OPS 300, and the 4th OPS 400, with respect to the optical path length L1 of the 1st OPS 100 having the shortest optical path length among them, the optical path length L3 of the 3rd OPS and the optical path length L4 of the 4th OPS are respectively set to satisfy the following conditions.

[0169] [Condition 1]

[0170] (n - 0.75) x L1 < L3 < (n + 0.25) x L1 (5)

[0171] It is further preferable that the optical path length L3 satisfy the above-described formula (6).

[0172] [Condition 2]

[0173] (m - 0.25) x L1 < L4 < (m + 0.25) x L1 (7)

[0174] n and m in the formula are each an integer of 2 or more. n and m can be the same value or different values, for example, n = 5 and m = 6. n and m can be determined independently of each other.

[0175] The optical path length L3 of the 3rd OPS 300 satisfies Condition 1, whereby the pulsed laser light circulating the delay optical path of the 3rd OPS 300 fills in the portion of the valley of the pulse waveform generated due to the delay optical path of the optical path length L1. Further, the optical path length L4 of the 4th OPS 400 satisfies Condition 2, whereby the pulsed laser light circulating the delay optical path of the 4th OPS 400 overlaps with the peak of the pulse waveform generated due to the delay optical path of the optical path length L1.

[0176] 4.2 Operation

[0177] The setting conditions of the optical path lengths L1 of the 1st OPS 100, the optical path length L2 of the 2nd OPS 200, and the optical path length L3 of the 3rd OPS 300 can be the same as in Embodiment 1.

[0178] The optical path length L3 of the 3rd OPS 300 is set so that the peak of the pulse waveform of the pulse that has passed through the 3rd OPS 300 fills the valley between the peaks of the pulse waveforms of the pulses that have passed through the 1st OPS 100, the 2nd OPS 200, and the 4th OPS 400. For example, the optical path length L3 is set to L3 = 29.75 [m] to 33.25 [m] (99.0 [ns] to 110.7 [ns]) so that the delay time in the case where the pulse has passed through the 3rd OPS 300 once is approximately 23.3 x 4.5 = 104.9 [ns].

[0179] The optical path length L4 of the 4th OPS 400 is set so that the peak of the pulse waveform of the pulse that has passed through the 4th OPS 400 overlaps the peak of the pulse waveform of the pulse that has come out of the 1st OPS 100. That is, the optical path length L4 is set to be an integer multiple of 2 or more of L1. The description of "integer multiple" here, as in the case of L2, is not limited to a strict integer multiple, but is approximately an integer multiple, and for example, can include a tolerance range of ±0.25 with respect to an integer.

[0180] As an example of the optical path length L4 of the 4th OPS 400, L4 = 40.25 [m] to 43.75 [m] (134.0 [ns] to 145.6 [ns]) is set so that the delay time in the case where the pulse has passed through the 4th OPS 400 once is approximately 23.3 x 6 = 139.8 [ns].

[0181] Figure 13 is a graph showing an example of setting of the optical path lengths L1, L2, L3, and L4 of the 1st OPS 100, the 2nd OPS 200, the 3rd OPS 300, and the 4th OPS 400, respectively. Here, an example of the pulse width (TIS width) achieved in the case where the optical path length L1 and the optical path length L2 are fixed to 7 m and 14 m, respectively, and the optical path length L3 and the optical path length L4 are changed is shown.

[0182] Figure 13 "Comparative Example 2" in is configured so that L3 is set to 5 times L1 and L4 is set to 6 times L1. In Comparative Example 2, the expanded pulse width is 467.3 ns, and TIS / (L3+L4) is 6.07. The value of TIS / (L3+L4) indicates the increase ratio of the pulse width with respect to the increase amount of the optical path length, and is an index indicating the efficiency of the OPS. The larger the value of TIS / (L3+L4) is, the more efficiently the pulse width can be expanded.

[0183] Examples F to L are examples in which the optical path length L3 and the optical path length L4 are set according to Condition 1 of Formula (5) and Condition 2 of Formula (7). Example F is an example in which L3 = 33.25 [m] = 5 x LI - 0.25 x LI, L4 = 42 [m] = 6 x LI. In Example F, a pulse width of 525.6 ns is achieved by an optical path increase of L3 + L4 = 75.25 m, and TIS / (L3 + L4) is 6.98. Example F can achieve a larger pulse width with a shorter optical path length than Comparative Example 2.

[0184] Example G is an example in which L3 = 32.55 [m] = 5 x LI - 0.35 x LI, L4 = 42 [m] = 6 x LI. Example G is a more preferable structure than Example F, and can achieve a larger pulse width with a shorter optical path length than Example F. Figure 13 The example among Examples F to L illustrated in the above-mentioned Embodiment 1 in which the pulse width is the largest is Example G.

[0185] Figure 14 A pulse waveform obtained in a case in which the OPS system 14B of Example G is used is shown. Figure 15 A pulse waveform obtained in a case in which the OPS system 14B of Example G is used is shown. As is apparent from these drawings, according to Example G, the difference between the peak and the trough of the pulse waveform is smaller than that of Comparative Example 2, and the pulse width can be expanded with a shorter optical path length than Comparative Example 2.

[0186] Figure 13 The example among Examples F to L illustrated in the above-mentioned Embodiment 1 in which TIS / (L3 + L4) is the largest is Example I. Example I has a larger pulse width and a larger TIS / (L3 + L4) than Comparative Example 2. Example I has a smaller pulse width than Example G, but has a larger TIS / (L3 + L4), and can efficiently expand the pulse width.

[0187] Figure 16 is a graph showing the change of TIS / (L3 + L4) with respect to the optical path length coefficient. The horizontal axis represents the optical path length coefficient, and the vertical axis represents TIS / (L3 + L4). In Figure 16 In the above-mentioned Embodiment 1, the optical path length coefficient k and TIS / (L3 + L4) of each of Comparative Example 2 and Examples F to J are plotted. According to Figure 16 It is apparent from these drawings that, from the viewpoint of efficiently expanding the pulse width with the shortest possible optical path length, the optical path length coefficient k is preferably 0.25 ≤ k ≤ 0.75, more preferably 0.35 ≤ k ≤ 0.65, and particularly preferably satisfies 0.5 ≤ k ≤ 0.65.

[0188] 4.3 Action / Effect

[0189] According to Embodiment 2, the pulse width can be efficiently expanded with a relatively short optical path length. The pulse width can be more efficiently expanded than in Embodiment 1.

[0190] 4.4 Others

[0191] The arrangement order of the 1st OPS 100, the 2nd OPS 200, the 3rd OPS 300, and the 4th OPS 400 on the optical path of the pulsed laser is not limited to Figure 12 For example, the arrangement order can be appropriately exchanged. If the combination of the values of the optical path lengths L1, L2, L3, and L4 is the same, the same pulse width is achieved regardless of the arrangement order of the 1st OPS 100, the 2nd OPS 200, the 3rd OPS 300, and the 4th OPS 400 on the optical path. Further, the 4th OPS 400 is not limited to the structure illustrated in Figure 12

[0192] 5. Modification of Laser Device

[0193] 5.1 Free-running Excimer Laser Device

[0194] 5.1.1 Structure

[0195] Figure 17 A structure example of a laser irradiation system to which a free-running excimer laser device 10C is applied is schematically shown. Regarding the structure shown in Figure 17 , a difference from Figure 7 is described.

[0196] Figure 7 The oscillator 12 shown in Figure 17 has a rear mirror 127 instead of the narrowbanding device 126. The rear mirror 127 can also be a high-reflectivity mirror. The oscillator 12C is an example of the "laser oscillator" in the present disclosure.

[0197] Further, Figure 17 The laser irradiation system shown in Figure 7 has a laser irradiation device 90 instead of the exposure device 80. The laser irradiation device 90 can be, for example, a laser processing machine that processes a substrate or the like using a laser, or a laser annealing device that polycrystallizes amorphous silicon, or the like. Further, the laser irradiation device 90 can also be a laser doping device that performs laser doping.

[0198] ​The laser irradiation device 90 has a laser irradiation control section 92. The laser irradiation control section 92 includes a processor, and controls the laser irradiation device 90. The laser irradiation control section 92 is connected to the laser control section 20. The laser irradiation control section 92 plays a similar role to the exposure control section 82 in Figure 7 with respect to the laser control section 20.

[0199] 5.1.2 Operation

[0200] Pulse laser of a free-running spectral waveform is output from the oscillator 12C. The pulse laser output from the oscillator 12C is pulse stretched by the OPS system 14A. The pulse laser output from the excimer laser device 10C is incident on the laser irradiation device 90.

[0201] In the laser irradiation device 90, a pulse laser is irradiated on a not-illustrated substrate or the like, an irradiated object, whereby processing, annealing, or doping of a material, or the like is performed. The irradiated object can be, for example, a semiconductor, glass, ceramic, or the like. After the pulse laser is irradiated on the irradiated object in the laser irradiation device 90, various electronic devices can be manufactured through a plurality of processes.

[0202] 5.1.3 Operation / Effect

[0203] According to the excimer laser device 10C, as with Embodiment 1, a pulse width can be efficiently stretched with a relatively short optical path length, and in Figure 17 , the speckle of the irradiation beam is also reduced. Further, the OPS system 14A of the excimer laser device 10C illustrated in Figure 17 may be replaced with the structure of the OPS system 14B in Figure 12 .

[0204] 5.2 Excimer Laser Device Including Solid Laser System as Master Oscillator

[0205] 5.2.1 Structure

[0206] Figure 18 A structure example of an excimer laser device 12D including a wavelength-variable solid laser system as a master oscillator is schematically illustrated. The excimer laser device 12D illustrated in Figure 7 and Figure 12 may be applied instead of the oscillator 12 illustrated in Figure 17 or the oscillator 12C illustrated in Figure 18 .

[0207] The excimer laser device 12D is a MOPA (Master Oscillator Power Amplifier) laser including a solid laser system 40 and an excimer amplifier 50. The solid laser system 40 is a wavelength variable solid laser system including a semiconductor laser 41 outputting a seed light, a semiconductor optical amplifier (SOA) 42, a titanium-doped sapphire amplifier 43 amplifying the seed light, a wavelength conversion system 46, and a solid laser control section 48.

[0208] The semiconductor laser 41 is a Distributed Feedback (DFB) semiconductor laser outputting a CW laser having a wavelength of about 773.6 nm. Hereinafter, the semiconductor laser 41 is referred to as "DFB laser 41". The DFB laser 41 is configured to control a temperature or a current value of a semiconductor laser element, thereby making the oscillation wavelength variable.

[0209] The SOA 42 is a semiconductor element converting the CW or pulsed seed light into a pulsed laser having a prescribed pulse width by passing a pulse current through the semiconductor. The SOA 42 pulses the CW laser output from the DFB laser 41, and outputs the pulsed laser after pulse amplification.

[0210] The titanium-doped sapphire amplifier 43 includes a titanium-doped sapphire crystal 44 and a pump pulsed laser 45. The titanium-doped sapphire crystal 44 is disposed on an optical path of the pulsed laser after pulse amplification by the SOA 42. The pump pulsed laser 45 is, for example, a laser device outputting 2nd harmonic light of a YLF laser. YLF (Yttrium Lithium Fluoride) is a solid laser crystal represented by the chemical formula LiYF4.

[0211] The wavelength conversion system 46 is a wavelength conversion system generating 4th harmonic light, including an LBO crystal and a KBBF crystal, not shown. The LBO crystal is a nonlinear optical crystal represented by the chemical formula LiB3O5. The KBBF crystal is a nonlinear optical crystal represented by the chemical formula KBe2BO3F2. These nonlinear optical crystals are respectively disposed on a rotation stage, not shown, configured so that an incident angle of light incident to the crystal can be varied. The wavelength conversion system 46 wavelength-converts the pulsed laser of 773.6 nm, and outputs a pulsed laser having a wavelength of about 193.4 nm.

[0212] The excimer amplifier 50 includes a cavity 52, a PPM 54, a charger 56, a convex mirror 61, and a concave mirror 62. The cavity 52 includes windows 71, 72, a pair of electrodes 74a, 74b, and an electrically insulating member 75. An ArF laser gas is housed inside the cavity 52.

[0213] The excimer amplifier 50 is configured to amplify the seed light of which the wavelength is 193.4 nm by 3 times by passing through the discharge space between the electrodes 74a, 74b.

[0214] The convex mirror 61 and the concave mirror 62 are configured to expand the pulsed laser output from the solid laser system 40 by 3 times on the outside of the cavity 52.

[0215] The seed light of which the wavelength is approximately 193.4 nm, which is incident to the excimer amplifier 50, is reflected by the convex mirror 61 and the concave mirror 62, and thereby passes through the discharge space between the electrodes 74a, 74b by 3 times. By this, the beam of the seed light is expanded and amplified.

[0216] 5.2.2 Action

[0217] The laser control section 20, after receiving the target wavelength λtand the target pulse energy Et, transmits the target wavelength λtto the solid laser control section 48, and sets the charging voltage to the charger 56 so as to become the target pulse energy Et.

[0218] The solid laser control section 48, after the target wavelength λtis input from the laser control section 20, changes the target oscillation wavelength λlt of the DFB laser 41 so that the wavelength of the laser output from the wavelength conversion system 46 becomes λt. The target oscillation wavelength λlt is 4 times the target wavelength λt (λlt = 4λt). The solid laser control section 48 changes the oscillation wavelength at high speed by controlling the current value flowing through the DFB laser 41.

[0219] Further, the solid laser control section 48 controls the rotation stage of each crystal so as to become the incident angle at which the wavelength conversion efficiency of the LBO crystal and the KBBF crystal in the wavelength conversion system 46 is the largest.

[0220] The solid laser control section 48, after the light emission trigger signal Tr is input from the laser control section 20, transmits the signal to the SOA 42 and the pump pulsed laser 45. As a result, the pulsed current is input to the SOA 42, and the pulsed laser amplified after passing through the SOA 42 is output from the SOA 42. Then, in the Ti: sapphire amplifier 43, further pulsed amplification is performed. The pulsed laser amplified by the Ti: sapphire amplifier 43 is incident to the wavelength conversion system 46. As a result, the pulsed laser of the target wavelength λtis output from the wavelength conversion system 46.

[0221] The laser control section 20, after receiving the light emission trigger signal Tr from the exposure control section 82 or the laser irradiation control section 92, gives a trigger signal to the switch 55 of the PPM 54 and the pump pulse laser 45, respectively, to cause discharge when the pulse laser output from the solid laser system 40 is incident to the discharge space of the cavity 52 of the excimer amplifier 50. As a result, the pulse laser output from the solid laser system 40 is amplified by 3 passes by the excimer amplifier 50.

[0222] The pulse laser amplified by the excimer amplifier 50 is incident to the OPS system 14A in Figure 7 or the OPS system 14B in Figure 12 or the OPS system 14A in Figure 17 The excimer laser device 12D is an example of the "laser oscillator" in the present disclosure.

[0223] The pulse laser output from the OPS system 14A or 14B is sampled by the beam splitter 162 of the monitor module 16, the pulse energy E is measured by the optical sensor 164, and the wavelength λ is measured by a wavelength monitor not shown.

[0224] The laser control section 20 controls the charging voltage of the charger 56 and the target oscillation wavelength λ1t of the DFB laser 41, respectively, to make the difference between the measured pulse energy E and the target pulse energy Et and the difference between the measured wavelength λ and the target wavelength λt close to 0, respectively.

[0225] The pulse laser that has passed through the beam splitter 162 of the monitor module 16 is incident to the exposure device 80 or the laser irradiation device 90 via the shutter 18.

[0226] 5.2.3 Modified Example

[0227] As an embodiment of the solid laser system, it is not limited to the example of Figure 18 For example, it can be a solid laser system including a DFB laser that outputs a laser with a wavelength of 1547.2 nm and a SOA, or a solid laser system in which the wavelength conversion system outputs an 8th harmonic light (193.4 nm light).

[0228] In Figure 18 , as the excimer amplifier 50, an example of a multi-pass amplifier is shown, but it is not limited to this example, and for example, it can be an amplifier having a Fabry-Perot resonator or a ring resonator. Furthermore, it is also possible to adopt a structure in which the excimer amplifier 50 shown in Figure 18 is omitted, and the pulse laser output from the solid laser system 40 is made incident to the OPS system 14A or the OPS system 14B to expand the pulse width. In this case, the solid laser system 40 is an example of the "laser oscillator" in the present disclosure.

[0229] 6. Hardware configuration of various control sections

[0230] The laser control section 20, the exposure control section 82, the laser irradiation control section 92, the solid laser control section 48, and the other control sections are configured using a processor. For example, these control sections can be realized by a combination of hardware and software of a computer including a processor. The software is synonymous with a program.

[0231] The computer is configured to include a CPU (Central Processing Unit) and a storage device such as a memory. The CPU is an example of a processor. A programmable controller is included in the concept of a computer. The storage device is a non-transitory computer-readable medium as a tangible object, for example, includes a memory as a main storage device and a storage as an auxiliary storage device. The computer-readable medium can be, for example, a semiconductor memory, a Hard Disk Drive (HDD) device, or a Solid State Drive (SSD) device, or a plurality of combinations thereof. A program executed by the processor is stored in the computer-readable medium. The storage device can also be included in the processor.

[0232] Furthermore, a part of the processing function of the computer can also be realized using an integrated circuit represented by an FPGA (Field Programmable Gate Array) and an ASIC (Application Specific Integrated Circuit).

[0233] Furthermore, it is also possible to realize the functions of a plurality of control sections with one computer. Furthermore, in the present disclosure, devices including a processor can also be connected to each other via a communication network such as a local area network or the Internet. In a distributed computing environment, program units can also be stored in memory storage devices on both local and remote sides.

[0234] 7. Method for manufacturing electronic device

[0235] Figure 19 An example of the configuration of the exposure apparatus 80 is schematically shown. The exposure apparatus 80 includes an illumination optical system 804 and a projection optical system 806. The illumination optical system 804 illuminates a reticle pattern of an unillustrated reticle arranged on a reticle stage RT with laser light incident from the excimer laser apparatus 10A. The projection optical system 806 reduces and projects the laser light after passing through the reticle, so as to form an image on an unillustrated workpiece arranged on a workpiece stage WT. The workpiece is a photosensitive substrate such as a semiconductor wafer on which a photoresist is coated.

[0236] The exposure apparatus 80 moves the reticle stage RT and the workpiece stage WT in parallel synchronously, thereby exposing the workpiece to laser light that reflects the pattern of the reticle. After the pattern of the reticle is transferred onto the semiconductor wafer by the above exposure process, a plurality of processes are performed, thereby enabling the manufacture of a semiconductor device. The semiconductor device is an example of an "electronic device" in the present disclosure. The excimer laser apparatus 10A is not limited, and the excimer laser apparatuses 10B or 10C, or the like can be used.

[0237] 8. Other

[0238] The above description is not restrictive, but is a simple example. Therefore, it is understood by those skilled in the art that modifications can be made to the embodiments of the present disclosure without departing from the scope of the claims. Furthermore, it is understood by those skilled in the art that the embodiments of the present disclosure can be used in combination.

[0239] The terms used throughout the specification and claims should be interpreted as "non-limiting" terms, unless explicitly stated otherwise. For example, the terms "comprising," "having," "including," and "containing," should be interpreted as "not excluding the presence of other structural elements not listed." In addition, the modifier "one" should be interpreted as meaning "at least one" or "one or more." Furthermore, the term "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 other elements and "A," "B," "C."

Claims

1. A laser device for a semiconductor exposure apparatus, comprising: a laser oscillator that outputs pulsed laser light; a first optical pulse stretcher disposed in an optical path of the pulsed laser light; a second optical pulse stretcher disposed in the optical path of the pulsed laser light; and a third optical pulse stretcher disposed in the optical path of the pulsed laser light, wherein, when a length of an optical path of a delay optical path of the first optical pulse stretcher is denoted as LI, a length of an optical path of a delay optical path of the second optical pulse stretcher is denoted as L2, a length of an optical path of a delay optical path of the third optical pulse stretcher is denoted as L3, and n is an integer of 2 or more, L2 is an integer of 2 or more times LI, L3 satisfies (n-0.75) x LI ≤ L3 ≤ (n-0.25) x LI, the laser oscillator is an excimer laser device including a narrowband module including a prism and a grating, the laser device further has a fourth optical pulse stretcher disposed in the optical path of the pulsed laser light, and m = n.

2. The laser device according to claim 1, wherein L3 satisfies (n-0.65) x LI ≤ L3 ≤ (n-0.35) x LI.

3. The laser device according to claim 1, wherein the first optical pulse stretcher, the second optical pulse stretcher, and the third optical pulse stretcher each include a beam splitter and four or more concave mirrors.

4. The laser device according to claim 1, wherein the first optical pulse stretcher, the second optical pulse stretcher, and the third optical pulse stretcher are disposed in series in the optical path of the pulsed laser light.

5. The laser device according to claim 1, wherein the first optical pulse stretcher, the second optical pulse stretcher, the third optical pulse stretcher, and the fourth optical pulse stretcher each include a beam splitter and four or more concave mirrors.

6. The laser device according to claim 1, wherein the first optical pulse stretcher, the second optical pulse stretcher, the third optical pulse stretcher, and the fourth optical pulse stretcher are disposed in series in the optical path of the pulsed laser light.

7. The laser device according to claim 1, wherein the laser oscillator is a free-running excimer laser device.

8. The laser device according to claim 1, wherein the laser oscillator is a solid-state laser system.

9. The laser device according to claim 8, wherein the solid-state laser system includes a semiconductor laser and a semiconductor optical amplifier.

10. A method for manufacturing an electronic device, comprising: generating pulsed laser light having an expanded pulse width by a laser device for a semiconductor exposure apparatus; outputting the laser light to an exposure device or a laser irradiation device; and exposing the laser light on a photosensitive substrate in the exposure device or irradiating the laser light on an irradiation target in the laser irradiation device to manufacture an electronic device, wherein the laser device includes: a laser oscillator that outputs pulsed laser light; a first optical pulse stretcher disposed in an optical path of the pulsed laser light; In a case where the optical path length of the delay optical path of the fourth optical pulse stretcher is L4, and m is an integer of 2 or more, L4 satisfies (m-0.25) x LI ≤ L4 ≤ (m+0.25) x LI, where, ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ a 2nd optical pulse stretcher configured in an optical path of the pulsed laser light; and a 3rd optical pulse stretcher configured in an optical path of the pulsed laser light, in a case where a length of an optical path of a delay optical path of the 1st optical pulse stretcher is assumed to be L1, a length of an optical path of a delay optical path of the 2nd optical pulse stretcher is assumed to be L2, a length of an optical path of a delay optical path of the 3rd optical pulse stretcher is assumed to be L3, and n is an integer of 2 or more, L2 is an integer of 2 or more times of L1, L3 satisfies (n-0.75) x L1 ≤ L3 ≤ (n-0.25) x L1, the laser oscillator is an excimer laser device including a narrowband module including a prism and a grating, the laser device further has a 4th optical pulse stretcher configured in an optical path of the pulsed laser light, In a case where the optical path length of the delay optical path of the fourth optical pulse stretcher is L4, and m is an integer of 2 or more, L4 satisfies (m-0.25) x LI ≤ L4 ≤ (m+0.25) x LI, where, m = n.

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