Pulse width extension device and method of manufacturing electronic device

Abstract

An impulse width expansion device of one aspect of the present disclosure has a polarization beam splitter and a transfer optical system. The transfer optical system has: a 1 / 4 wave mirror pair including a first 1 / 4 wave mirror that reflects a pulse laser with a phase shift of 1 / 4 wavelength and a second 1 / 4 wave mirror that reflects the pulse laser after the reflection by the first 1 / 4 wave mirror with a phase shift of 1 / 4 wavelength; and a mirror pair that is disposed on an optical path before and after the 1 / 4 wave mirror pair or an optical path between the 1 / 4 wave mirror pair. The transfer optical system transfers an image of the input pulse laser in the polarization beam splitter on an optical path between the 1 / 4 wave mirror pair as a first transfer image at equal magnification, and transfers the first transfer image in the polarization beam splitter as a second transfer image at equal magnification.

Description

Technical Field

[0001] The present disclosure relates to a pulse width stretching apparatus and a method for manufacturing an electronic device. Background Art

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

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

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: U.S. Patent No. 6,067,311

[0007] Patent Document 2: Japanese Patent Application Laid-Open No. 2006-186046 Summary of the Invention

[0008] A pulse width expansion device according to one aspect of the present disclosure comprises: a polarization beam splitter that transmits pulse laser light of a first polarization direction in linearly polarized pulse laser light at a first transmittance, and reflects pulse laser light of a second polarization direction orthogonal to the first polarization direction at a first reflectivity and transmits it at a second transmittance; and a transfer optical system that causes the pulse laser light reflected by the polarization beam splitter to be reflected by a plurality of concave mirrors and returned to the polarization beam splitter, wherein the polarization beam splitter synthesizes the pulse laser light of the second polarization direction that is transmitted at the second transmittance in the input pulse laser light input from the outside and a portion of the pulse laser light returned from the transfer optical system. And output, the transfer optical system has: a 1 / 4 wavelength mirror pair, which includes a first 1 / 4 wavelength mirror that reflects the phase of the pulsed laser with a 1 / 4 wavelength shift and a second 1 / 4 wavelength mirror that reflects the phase of the pulsed laser after being reflected by the first 1 / 4 wavelength mirror with a 1 / 4 wavelength shift; and a reflection mirror pair, which is arranged in the optical path before and after the 1 / 4 wavelength mirror pair or the optical path between the 1 / 4 wavelength mirror pairs. The transfer optical system transfers the image of the input pulsed laser in the polarization beam splitter into a first transfer image at the same magnification on the optical path between the 1 / 4 wavelength mirror pairs, and transfers the first transfer image into a second transfer image at the same magnification on the polarization beam splitter.

[0009] Another aspect of the present disclosure provides a method for manufacturing an electronic device, comprising the following steps: generating a pulsed laser after pulse width expansion by a laser system, outputting the pulsed laser to an exposure device, exposing the pulsed laser on a photosensitive substrate in the exposure device to manufacture an electronic device, wherein the laser system comprises a laser device and a pulse width expansion device, wherein the laser device generates a linearly polarized pulsed laser, and the pulse width expansion device comprises: a polarization beam splitter, which transmits a pulsed laser of a first polarization direction in the linearly polarized pulsed laser at a first transmittance, and reflects a pulsed laser of a second polarization direction orthogonal to the first polarization direction at a first reflectivity and transmits it at a second transmittance; and a transfer optical system, which reflects the pulsed laser reflected by the polarization beam splitter on a plurality of concave mirrors and returns to the polarization beam splitter, and the polarization beam splitter transmits the pulsed laser from the outside. The pulse laser of the second polarization direction transmitted with the second transmittance in the input pulse laser light inputted partially and the pulse laser light of a part of the pulse laser light returned from the transfer optical system are synthesized and outputted, the transfer optical system comprising: a 1 / 4 wavelength mirror pair, which includes a first 1 / 4 wavelength mirror which reflects the pulse laser light with a phase shift of 1 / 4 wavelength and a second 1 / 4 wavelength mirror which reflects the pulse laser light after being reflected by the first 1 / 4 wavelength mirror with a phase shift of 1 / 4 wavelength; and a reflecting mirror pair which is arranged in the optical path before and after the 1 / 4 wavelength mirror pair or in the optical path between the 1 / 4 wavelength mirror pairs, the transfer optical system transfers the image of the input pulse laser light in the polarization beam splitter into a first transfer image at equal magnification on the optical path between the 1 / 4 wavelength mirror pairs, and transfers the first transfer image into a second transfer image at equal magnification on the polarization beam splitter.

[0010] A pulse width expansion device according to another aspect of the present disclosure comprises: a polarization beam splitter which transmits a pulse laser of a first polarization direction in a linearly polarized pulse laser at a first transmittance, and reflects a pulse laser of a second polarization direction orthogonal to the first polarization direction at a first reflectivity and transmits it at a second transmittance; and a transfer optical system which reflects the pulse laser reflected by the polarization beam splitter on a plurality of concave mirrors and returns the pulse laser to the polarization beam splitter, the polarization beam splitter synthesizes and outputs a portion of the pulse laser of the second polarization direction transmitted at the second transmittance in an input pulse laser input from the outside and the pulse laser returned from the transfer optical system, the transfer optical system comprising: a first transfer optical system which includes a method for shifting the phase of the pulse laser by 1 / 4 wavelength A first quarter wavelength mirror for reflection and a first reflecting mirror for reflecting the pulsed laser after being reflected by the first quarter wavelength mirror toward the first quarter wavelength mirror; and a second transfer optical system, which includes a second quarter wavelength mirror for reflecting the pulsed laser with a phase shift of 1 / 4 wavelength and a second reflecting mirror for reflecting the pulsed laser after being reflected by the second quarter wavelength mirror toward the second quarter wavelength mirror, the first transfer optical system transfers the image of the input pulsed laser in the polarization beam splitter into a first transfer image at the same magnification at the first reflecting mirror, and transfers the first transfer image into a second transfer image at the same magnification at the polarization beam splitter, the second transfer optical system transfers the second transfer image into a third transfer image at the same magnification at the second reflecting mirror, and transfers the third transfer image into a fourth transfer image at the same magnification at the polarization beam splitter. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0012] Figure 1 This is a diagram for explaining the width of spectral lines.

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

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

[0015] Figure 4 It shows Figure 3 A graph showing a histogram of the brightness and darkness of a speckle image is shown.

[0016] Figure 5 is a diagram showing the structure of a laser system.

[0017] Figure 6 This is a diagram showing the structure of the dual-path OPS according to the first embodiment.

[0018] Figure 7 yes Figure 6F-direction view in.

[0019] Figure 8 1 and 2 are diagrams showing a modified example of the positional relationship between the quarter-wavelength mirror and the high-reflection mirror.

[0020] Figure 9 1 and 2 are diagrams showing a modified example of the positional relationship between the quarter-wavelength mirror and the high-reflection mirror.

[0021] Figure 10 1 and 2 are diagrams showing a modified example of the positional relationship between the quarter-wavelength mirror and the high-reflection mirror.

[0022] Figure 11 : is a diagram showing the optical paths of the first pulse laser and the second pulse laser output from the dual-path OPS.

[0023] Figure 12 This is a diagram showing the structure of the dual-path OPS according to the second embodiment.

[0024] Figure 13 It shows Figure 12 F-direction view in.

[0025] Figure 14 : is a diagram showing the optical paths of the first pulse laser and the second pulse laser output from the dual-path OPS.

[0026] Figure 15 1 is a diagram showing simulation results of pulse waveform expansion of output pulse laser light from a laser system.

[0027] Figure 16 This is a partial top view of the dual-path OPS according to the first modification of the second embodiment.

[0028] Figure 17 This is a partial side view of the dual-path OPS according to the first modification of the second embodiment.

[0029] Figure 18 It is a partial side view showing the state after the angle adjustment stage is adjusted.

[0030] Figure 19 This is a partial top view of the dual-path OPS of Modification 2 of Implementation Example 2.

[0031] Figure 20 This is a partial side view of the dual-path OPS of Modification Example 1.

[0032] Figure 21 It is a partial side view showing the state after the angle adjustment stage is adjusted.

[0033] Figure 22 This is a top view of a 45-degree right-angle prism element of a third variation of the second embodiment.

[0034] Figure 23 This is a diagram showing the structure of the dual-path OPS according to the third embodiment.

[0035] Figure 24 It is a diagram schematically showing a configuration example of an exposure apparatus. DETAILED DESCRIPTION

[0036] -Table of contents-

[0037] 1. Explanation of terms

[0038] 1.1 Definition of E95

[0039] 1.2 Definition of coherence length

[0040] 1.3 Definition of Speckle Contrast

[0041] 2. Laser System Overview

[0042] 2.1 Structure

[0043] 2.2 Action

[0044] 2.3 Function

[0045] 3.Topic

[0046] 4. Implementation Method 1

[0047] 4.1 Structure

[0048] 4.1.1 Configuration of 1 / 4 Wavelength Mirror and High Reflection Mirror

[0049] 4.2 Action

[0050] 4.3 Action / Effect

[0051] 5. Implementation Method 2

[0052] 5.1 Structure

[0053] 5.1.1 Configuration of 1 / 4 Wavelength Mirror and High Reflection Mirror

[0054] 5.2 Action

[0055] 5.3 Action / Effect

[0056] 6. Modification 1 of Implementation 2

[0057] 6.1 Structure

[0058] 6.2 Action

[0059] 6.3 Action / Effect

[0060] 7. Modification 2 of Implementation 2

[0061] 7.1 Structure

[0062] 7.2 Action

[0063] 7.3 Function / Effect

[0064] 8. Variant Example 3 of Embodiment 2

[0065] 8.1 Structure

[0066] 8.2 Action

[0067] 8.3 Function / Effect

[0068] 9. Embodiment 3

[0069] 9.1 Structure

[0070] 9.2 Action

[0071] 9.3 Function / Effect

[0072] 10. Manufacturing Method of Electronic Device

[0073] 11. Others

[0074] Next, 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 actions described in each embodiment are not necessarily all essential to the structures and actions of the present disclosure. In addition, the same reference numerals are assigned to the same structural elements and repeated descriptions are omitted.

[0075] 1. Explanation of Terms

[0076] The terms used in this specification are defined as follows.

[0077] 1.1 Definition of E95

[0078] 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 called the line width threshold Thresh (0 < Thresh < 1). For example, the half value of the peak is called the line width threshold of 0.5. In particular, the full width W / 2 of the spectral waveform with a line width threshold of 0.5 is called the full width at half maximum or FWHM (Full Width at Half Maximum).

[0079] As Figure 2 shown, the spectral purity, for example, 95% purity E95 refers to the full width W95% of the part that occupies 95% centered on the wavelength λ0 in all spectral energies, and the following formula (1) holds.

[0080] [Mathematical Formula 1]

[0081]

[0082] In addition, unless otherwise specified, in this specification, the spectral purity is described as E95.

[0083] 1.2 Definition of coherence length

[0084] When the central wavelength of the laser light is λ0 and the line width is Δλ, the coherence length of the laser light can be expressed by the following formula (2).

[0085] [Mathematical formula 2]

[0086]

[0087] 1.3 Definition of Speckle Contrast

[0088] Speckle refers to the bright and dark spots produced by the scattering of laser light in a random medium. Figure 3 is a diagram showing an example of a speckle image obtained by photographing a pattern composed of bright and dark spots. Figure 4 It shows Figure 3 A graph showing a histogram of the brightness and darkness of a speckle image is shown.

[0089] As a speckle evaluation index, speckle contrast SC is generally used. When the standard deviation of the intensity of the speckle image is σ and the average intensity of the speckle image is 1 macron (a macron is written above 1), speckle contrast SC can be expressed by the following equation (3).

[0090] [Mathematical formula 3]

[0091]

[0092] The term "parallel" in this specification may include the concept of "approximately parallel" to the extent that it can be considered substantially parallel in a technical sense. Furthermore, the term "perpendicular" or "orthogonal" in this specification may include the concept of "approximately perpendicular" or "approximately orthogonal" to the extent that it can be considered substantially perpendicular or substantially orthogonal in a technical sense. The term "45 degrees" in this specification may include the concept of "approximately 45 degrees" to the extent that it can be considered substantially equivalent to 45 degrees in a technical sense.

[0093] 2. Laser System Overview

[0094] 2.1 Structure

[0095] Figure 5 1 is a diagram showing the structure of the laser system 1. Figure 5 As shown, the laser system 1 includes an excimer laser device 2 and a pulse width expansion device 3 .

[0096] The excimer laser device 2 generates pulsed laser light using an optical resonator and includes a master oscillator (MO) 10 , an MO beam steering unit 20 , a power oscillator (PO) 30 , and a PO beam steering unit 40 .

[0097] MO10 includes a Line Narrow Module (LNM) 11 , a cavity 14 , and an output coupling mirror (OC) 17 .

[0098] The LNM 11 includes a prism beam expander 12 for narrowing the spectral line width and a grating 13. The prism beam expander 12 and the grating 13 are arranged in a Littrow configuration so that the incident angle and the diffraction angle coincide with each other.

[0099] OC17 is a reflective mirror with a reflectivity of 40% to 60%. OC17 and LNM11 are arranged to form an optical resonator.

[0100] Cavity 14 is positioned on the optical path of the optical resonator. It includes a pair of discharge electrodes 15 and two windows, window 16a and window 16b, through which the pulsed laser light passes. Cavity 14 contains excimer laser gas. The excimer laser gas may include, for example, Ar gas or Kr gas as a rare gas, F2 gas as a halogen gas, and Ne gas as a buffer gas.

[0101] The MO beam steering unit 20 includes a high reflection mirror 21 a and a high reflection mirror 21 b . The high reflection mirror 21 a and the high reflection mirror 21 b are arranged so that the pulse laser light output from the MO 10 is incident on the PO 30 .

[0102] PO 30 includes a rear mirror 31, a cavity 32, and an OC 35. The rear mirror 31 and the OC 35 are configured to form an optical resonator.

[0103] Cavity 32 is located on the optical path of the optical resonator. It includes a pair of discharge electrodes 33 and two windows, window 34a and window 34b, through which the pulsed laser light passes. Cavity 32 contains excimer laser gas. Cavity 32 has the same structure as cavity 14.

[0104] The rear mirror 31 is a reflective mirror having a reflectivity of 50% to 90%, and the OC 35 is a reflective mirror having a reflectivity of 10% to 30%.

[0105] The PO beam steering unit 40 includes a high reflection mirror 41 a and a high reflection mirror 41 b . The high reflection mirror 41 a and the high reflection mirror 41 b are arranged so that the pulse laser light output from the PO 30 is incident on the pulse width expander 3 .

[0106] The pulse width expander 3 is a device that expands the pulse width of the pulse laser light output from the excimer laser device 2. The pulse width expander 3 includes an optical pulse stretcher (OPS) 50 and an OPS 60.

[0107] OPS50 includes a beam splitter 52 and four concave mirrors 54.

[0108] Beam splitter 52 is positioned on the optical path of the pulsed laser light output from PO beam steering unit 40. Beam splitter 52 is a mirror that transmits a portion of the incident pulsed laser light and reflects the remainder. The reflectivity of beam splitter 52 is preferably 40% to 70%, more preferably approximately 60%. Beam splitter 52 is positioned so that the pulsed laser light, after passing through it, enters OPS 60.

[0109] The four concave mirrors 54 form a delayed optical path of the pulsed laser light reflected by the first surface of the beam splitter 52. The four concave mirrors 54 are respectively composed of a concave mirror 54a, a concave mirror 54b, a concave mirror 54c, and a concave mirror 54d, each having a focal length of F1.

[0110] Concave mirrors 54a and 54b are arranged so that the pulsed laser light reflected from the first surface of beam splitter 52 is reflected from concave mirror 54a and incident on concave mirror 54b. Concave mirrors 54c and 54d are arranged so that the pulsed laser light reflected from concave mirror 54b is reflected from concave mirror 54c and incident on concave mirror 54d. Furthermore, concave mirror 54d is arranged so that the pulsed laser light reflected from concave mirror 54d is incident on the second surface of beam splitter 52, opposite to the first surface.

[0111] Concave mirrors 54a and 54bb are arranged so that the pulsed laser light reflected from the first surface of beam splitter 52 forms an image on the first surface of beam splitter 52 at an equal magnification (1:1) as a first image. Concave mirrors 54c and 54d are arranged so that the first image forms a second image on the second surface of beam splitter 52 at a 1:1 ratio.

[0112] Here, the length of the delay optical path L for one turn of the delay optical path formed by the four concave mirrors 54 is OPS1 It is configured to be longer than the coherence length Lc of the pulse laser, that is, L OPS1 ≥Lc. The coherence length Lc of the pulsed laser can be calculated using the above formula (2). For example, the coherence length Lc of a pulsed laser with a line width Δλ = 0.3pm and a central wavelength λ0 = 193.35nm is 0.125m. As an example, the optical path length L of one turn of the OPS50 delay is OPS1 is 7m.

[0113] OPS 60 is placed on the optical path of the pulsed laser output from OPS 50. OPS 60 includes a beam splitter 62 and four concave mirrors 64. The four concave mirrors 64 are respectively composed of concave mirrors 64a, 64b, 64c, and 64d, each having a focal length of F2 greater than F1.

[0114] The beam splitter 62 and four concave mirrors 64 of the OPS 60 are arranged in the same manner as the beam splitter 52 and four concave mirrors 54 of the OPS 50. As an example, the optical path length L of one turn of the delay of the OPS 60 is OPS2 It is 14m.

[0115] 2.2 Action

[0116] The operation of laser system 1 will be described. When discharge occurs in cavity 14, the laser gas is excited, and pulsed laser light is output from OC 17. This pulsed laser light is narrowed in bandwidth by the optical resonator formed by OC 17 and LNM 11. This pulsed laser light passes through MO beam steering unit 20 and is incident on rear mirror 31 of PO 30 as seed light.

[0117] Synchronously with the entry of seed light after passing through rear mirror 31, discharge occurs in cavity 32. As a result, the laser gas is excited, and the seed light is amplified by the Fabry-Perot optical resonator formed by OC 35 and rear mirror 31. The amplified pulsed laser light is then output from OC 35. The pulsed laser light output from OC 35 enters pulse width expansion device 3 via PO beam steering unit 40.

[0118] The pulsed laser light incident on the pulse width expander 3 is incident on the first surface of the beam splitter 52 of the OPS 50. A portion of the pulsed laser light incident on the first surface of the beam splitter 52 is transmitted through the beam splitter 52 and output from the OPS 50 as the first pulsed laser light of zero-surround light that is not surrounded by the delay optical path.

[0119] Of the pulsed laser light incident on the first surface of beam splitter 52, the pulsed laser light reflected by the first surface enters the delay optical path and is reflected by concave mirrors 54a and 54b. The pulsed laser light image reflected by the first surface of beam splitter 52 is formed into a 1:1 primary transfer image by concave mirrors 54a and 54b. The primary transfer image is then formed into a 1:1 secondary transfer image by concave mirrors 54c and 54d on the second surface of beam splitter 52.

[0120] A portion of the pulsed laser light incident on the second surface of the beam splitter 52 from the concave mirror 54d is reflected by the second surface of the beam splitter 52 and output from the OPS 50 as a second pulsed laser light that has made one round trip on the delayed optical path. This second pulsed laser light is output after being delayed by a delay time Δt1 from the first pulsed laser light. When the speed of light is c, this Δt1 can be expressed as Δt1 = L OPS1 / c.

[0121] Of the pulsed laser light incident on the second surface of beam splitter 52 as the secondary transfer image, the pulsed laser light that has passed through beam splitter 52 further enters the delay optical path, is reflected by four concave mirrors 54, and is incident again on the second surface of beam splitter 52. The pulsed laser light reflected by the second surface of beam splitter 52 is then output from OPS 50 as a third pulsed laser light, consisting of two-circular light that has made two turns along the delay optical path. This third pulsed laser light is outputted delayed by a delay time Δt1 from the second pulsed laser light.

[0122] Then, by repeatedly looping the light around the delay optical path, the fourth to n-th pulsed laser lights are output from the OPS 50. As the number of loops of the delay optical path increases, the light intensity of the pulsed light output from the OPS 50 decreases.

[0123] The second to nth laser pulses are delayed by an integral multiple of the delay time Δt1 relative to the first laser pulse and then synthesized and output. This causes the pulse waveforms to overlap. As a result, the pulse width is expanded (broadened). Since the first to nth laser pulses overlap over an optical path exceeding the coherence length, the coherence of the laser beams is reduced.

[0124] Regarding the pulse laser output from OPS50, the pulse width is similarly expanded by OPS60, and the coherence is further reduced.

[0125] The pulsed laser light after passing through OPS50 and OPS60 is output from the laser system 1. At this time, the pulsed laser light may be output from the laser system 1 through a monitor module (not shown) that measures pulse energy, line width, wavelength, and the like.

[0126] 2.3 Function

[0127] According to the laser system 1, the pulse width of the pulsed laser light output from the excimer laser device 2 is expanded by the pulse width expander 3, thereby reducing the temporal energy density of the pulsed laser light output from the laser system 1. This can reduce damage to the optical elements in the subsequent stages of the laser system 1. In addition, expanding the pulse width also has the effect of reducing the coherence of the pulsed laser light.

[0128] 3.Topic

[0129] With the advancement of high-resolution exposure in electronic device manufacturing, there is a demand for lower coherence in the laser light output from exposure laser systems. Therefore, the delay path length of the OPS needs to be extended by at least two times. However, due to space constraints, an OPS with a delay path length greater than two times is difficult to incorporate into existing laser systems.

[0130] 4. Implementation Method 1

[0131] The dual path OPS 70 of the first embodiment will be described. Figure 5 The OPS60 of the pulse width expansion device 3 shown in the figure is applied. Hereinafter, the same reference numerals are given to the parts identical to those of the OPS60 and their detailed descriptions are omitted. In addition, the dual-path OPS70 can also be used instead of Figure 5 The OPS 50 of the pulse width stretching device 3 shown in the figure can be used instead of the OPS 50 and the OPS 60. The dual-path OPS 70 can also be incorporated into the excimer laser device 2.

[0132] 4.1 Structure

[0133] Figure 6 : is a diagram showing the structure of the dual path OPS70 of the first embodiment. Figure 6 As shown, the dual-path OPS 70 includes a polarization beam splitter 72 , a transfer optical system 73 , and an optical plate 78 .

[0134] The polarization beam splitter 72 uses linearly polarized pulsed laser light incident from outside the dual-path OPS 70 as input pulsed laser light. It reflects 60% of the S-polarized (an example of the second polarization direction) pulsed laser light within the input pulsed laser light (an example of the first reflectivity) and transmits 40% of the S-polarized (an example of the second polarization direction) pulsed laser light (an example of the second transmittance). Furthermore, the polarization beam splitter 72 transmits approximately 100% of the P-polarized (an example of the first polarization direction) pulsed laser light within the incident linearly polarized pulsed laser light (an example of the first polarization direction). The first surface of the polarization beam splitter 72 is arranged to be inclined 45 degrees relative to the optical axis of the input pulsed laser light.

[0135] The transfer optical system 73 includes four concave mirrors 64 (an example of a plurality of concave mirrors), a quarter-wavelength mirror pair 74, and a high-reflection mirror pair 76. The transfer optical system 73 reflects the pulsed laser light reflected by the polarization beam splitter 72 at the four concave mirrors 64 and returns it to the polarization beam splitter 72.

[0136] The quarter-wavelength mirror pair 74 and the high-reflection mirror pair 76 function as a retarder that rotates the polarization direction of the linearly polarized pulsed laser light by 90 degrees.

[0137] The quarter-wavelength mirror pair 74 is composed of a quarter-wavelength mirror 74a and a quarter-wavelength mirror 74b. The quarter-wavelength mirror 74a and the quarter-wavelength mirror 74b are optical elements that shift the phase of the incident pulsed laser light by 1 / 4 wavelength and reflect the light.

[0138] The high reflector pair 76 is composed of a high reflector 76a (an example of a first reflector) and a high reflector 76b (an example of a second reflector). The high reflector 76a and the high reflector 76b are optical elements having a reflectivity of 99% or more, for example.

[0139] High-reflection mirrors 76a and 76b are coated with a high-reflection film on the surface of a substrate. The substrate material includes at least one of CaF2 and SiO2. The high-reflection film material includes at least one of AlF3, GdF3, BaF2, SrF2, NaF2, MgF2, LaF3, a mixture of GdF3 and NdF3, Al2O3, SiO2, F-doped SiO2, TiO2, and SrF2. When n is an integer greater than 1, the thickness of the high-reflection film is λ0 / 2n.

[0140] The optical plates 78 are respectively connected to the holding members 79 (see Figure 7 ) supports the polarization beam splitter 72, four concave mirrors 64, a quarter-wavelength mirror pair 74, and a high-reflection mirror pair 76. The positions and postures of the polarization beam splitter 72, four concave mirrors 64, a quarter-wavelength mirror pair 74, and a high-reflection mirror pair 76 are adjusted relative to the optical path of the pulsed laser.

[0141] Concave mirror 64a and concave mirror 64b are arranged so that the pulsed laser light reflected by polarization beam splitter 72 is reflected by concave mirror 64a and incident on concave mirror 64b. Concave mirror 64b is arranged so that the pulsed laser light reflected by concave mirror 64b is incident on quarter wavelength mirror 74a.

[0142] The quarter-wavelength mirror pair 74 is disposed on the optical path between the concave mirror 64b and the concave mirror 64c. The high-reflection mirror pair 76 is disposed on the optical path between the quarter-wavelength mirror pair 74. The high-reflection mirror pair 76 may also be disposed on the optical path before and after the quarter-wavelength mirror pair 74.

[0143] The quarter-wavelength mirror 74 a and the high-reflection mirror 76 a are arranged so that the pulsed laser light reflected by the concave mirror 64 b is reflected by the quarter-wavelength mirror 74 a and enters the high-reflection mirror 76 a .

[0144] The high reflection mirror 76 b and the quarter wavelength mirror 74 b are arranged so that the pulse laser light reflected by the high reflection mirror 76 a is reflected by the high reflection mirror 76 b and enters the quarter wavelength mirror 74 b .

[0145] Concave mirror 64c and concave mirror 64d are arranged so that the pulsed laser light reflected by quarter wavelength mirror 74b is reflected by concave mirror 64c and incident on concave mirror 64d. Concave mirror 64d is further arranged so that the pulsed laser light reflected by concave mirror 64d is incident on polarization beam splitter 72.

[0146] The distance between the polarization beam splitter 72 and the concave mirror 64a, and the distance between the concave mirror 64d and the polarization beam splitter 72 are equal to the focal length F2. The distance between the concave mirrors 64a and 64b, and the distance between the concave mirrors 64c and 64d, are each twice the focal length F2. Furthermore, the distance on the optical path between the concave mirrors 64b and 64c is twice the focal length F2.

[0147] The concave mirror 64a, the concave mirror 64b, the quarter-wavelength mirror 74a, and the high reflector 76a are configured to transfer the image on the first surface of the polarization beam splitter 72 to the first image at a 1:1 ratio between the high reflector 76a and the high reflector 76b.

[0148] High-reflection mirror 76b, quarter-wavelength mirror 74b, concave mirror 64c, and concave mirror 64d are configured to transfer the first image to the second image on the first surface of polarization beam splitter 72 at a 1:1 ratio. In an actual dual-path OPS, the optical path length between the first and second surfaces of the polarization beam splitter at the OPS entrance is significantly shorter than the optical path length of one full rotation of the OPS optical path. Therefore, even if the transfer location of the second image is set to the second surface, the OPS fully functions. In the following description, the transfer location of the second image is set to the second surface as an example.

[0149] 4.1.1 Configuration of 1 / 4 Wavelength Mirror and High Reflection Mirror

[0150] The optical path from the 1 / 4 wavelength mirror 74a to the high reflection mirror 76a is formed at an angle of 45 degrees with respect to the optical path to the 1 / 4 wavelength mirror 74a. Figure 6 The polarization direction perpendicular to the paper plane and the polarization direction along the paper plane form an angle of 45 degrees.

[0151] Figure 7 yes Figure 6 The F-direction view in Figure 7 As shown, the high reflective mirror 76a is opposite to the 1 / 4 wavelength mirror 74a, so as to be opposite to the Figure 6 The 1 / 4 wavelength mirror 74a bends the optical path of the pulsed laser light at an angle of 45 degrees toward the optical plate 78 and toward the high reflective mirror 76a.

[0152] Similarly, the high reflective mirror 76b is also opposite to the 1 / 4 wavelength mirror 74b, so as to be opposite to the Figure 6 The high reflective mirror 76b bends the pulse laser light path at an angle of 45 degrees toward the side opposite to the optical plate 78 and toward the quarter-wavelength mirror 74b.

[0153] The optical path between the high reflection mirror 76a and the high reflection mirror 76b is configured to be parallel to the optical path from the concave mirror 64b to the quarter wavelength mirror 74a and the optical path from the quarter wavelength mirror 74b to the concave mirror 64c.

[0154] In addition, the positional relationship between the 1 / 4 wavelength mirror 74a and the high reflection mirror 76a is not limited to Figure 7 In the example shown, the 1 / 4 wavelength mirror 74a bends the optical path of the pulsed laser at an angle of 45 degrees toward the high reflective mirror 76a. Figure 8 、 Figure 9 、 Figure 10 Similarly, the high reflector 76b can also be arranged relative to the 1 / 4 wavelength mirror 74b as shown. Figure 8 、 Figure 9 、 Figure 10 Configure as shown respectively.

[0155] 4.2 Action

[0156] The operation of the dual-path OPS70 is described below. S-polarized pulsed laser light is incident on the dual-path OPS70. Figure 6 In the figure, the linear polarization perpendicular to the paper plane is S polarization, and the linear polarization along the paper plane is P polarization.

[0157] The S-polarized pulsed laser light incident on the dual-path OPS 70 is incident on the first surface of the polarization beam splitter 72. The polarization beam splitter 72 reflects 60% of the incident S-polarized pulsed laser light and transmits 40%. The 40% of the S-polarized pulsed laser light that has passed through the polarization beam splitter 72 is output from the dual-path OPS 70 as the first pulsed laser light, which is zero-surround light and does not bypass the delay optical path.

[0158] 60% of the S-polarized pulsed laser light reflected by the polarization beam splitter 72 is reflected by the concave mirrors 64 a and 64 b and enters the quarter-wavelength mirror 74 a.

[0159] The quarter-wavelength mirror 74a is tilted 45 degrees relative to the electric field oscillation axis of the incident pulse laser light, thereby imparting quarter-wavelength phase modulation to each polarization component of the pulse laser light, converting the S-polarized pulse laser light into circularly polarized pulse laser light.

[0160] The pulsed laser light converted into circular polarization is reflected by high reflectivity without changing its phase by high reflective mirrors 76a and 76b, and then enters quarter-wavelength mirror 74b. The pulsed laser light image reflected by the first surface of polarization beam splitter 72 is transferred by concave mirrors 64a, 64b, and quarter-wavelength mirror 74a to form a 1:1 primary transfer image at a position midway between the optical paths of high reflective mirrors 76a and 76b.

[0161] The quarter-wavelength mirror 74 b further imparts quarter-wavelength phase modulation to each polarization component of the circularly polarized pulsed laser light incident from the high-reflection mirror 76 b , thereby converting the circularly polarized pulsed laser light into P-polarized pulsed laser light.

[0162] The pulsed laser light converted to P polarization is reflected by concave mirrors 64c and 64d, and enters the second surface of polarization beam splitter 72 perpendicularly to the optical axis of the input pulsed laser light. At this point, the pulsed laser light has completed one rotation along the delayed optical path. The primary transfer image is transferred to the second surface of polarization beam splitter 72 as a 1:1 secondary transfer image by quarter-wavelength mirror 74b, concave mirror 64c, and concave mirror 64d.

[0163] Thus, the optical path for transferring the image of the input pulsed laser light on the first surface of the polarization beam splitter 72 into a first transfer image and the optical path for transferring the first transfer image into a second transfer image on the second surface of the polarization beam splitter 72 are symmetrical with respect to the optical path of the output pulsed laser light. Furthermore, the optical path for transferring the image of the input pulsed laser light on the first surface of the polarization beam splitter 72 into a first transfer image and the optical path for transferring the first transfer image into a second transfer image on the second surface of the polarization beam splitter 72 are preferably arranged to be linearly symmetrical about the optical path of the output pulsed laser light as an axis of symmetry.

[0164] The P-polarized pulsed laser light reflected by the concave mirror 64 d and incident on the second surface of the polarization beam splitter 72 is transmitted by the polarization beam splitter 72 at approximately 100%, enters the second-turn delay optical path, and is incident on the concave mirror 64 a .

[0165] Concave mirrors 64a and 64b reflect the incident pulsed laser light, causing it to enter quarter-wavelength mirror 74a. Quarter-wavelength mirror 74a converts the P-polarized pulsed laser light into circularly polarized pulsed laser light. The circularly polarized pulsed laser light is reflected by high-reflection mirrors 76a and 76b at a high reflectivity without changing its phase, and enters quarter-wavelength mirror 74b.

[0166] The second transfer image is transferred into a third transfer image at a 1:1 ratio by the concave mirror 64 a , the concave mirror 64 b , and the quarter-wavelength mirror 74 a at a position intermediate between the high reflection mirror 76 a and the high reflection mirror 76 b .

[0167] Quarter-wavelength mirror 74b further phase-modulates each polarization component of the circularly polarized pulsed laser light incident from high-reflection mirror 76b by a quarter wavelength, converting the circularly polarized pulsed laser light into S-polarized pulsed laser light. The S-polarized pulsed laser light is reflected by concave mirrors 64c and 64d and re-enters the second surface of polarization beam splitter 72. At this point, the pulsed laser light has completed two rotations along the delayed optical path. The third transfer image is transferred to a 1:1 fourth transfer image at the position of polarization beam splitter 72 by quarter-wavelength mirror 74b, concave mirrors 64c, and 64d.

[0168] Of the S-polarized pulsed laser light reflected by the concave mirror 64 d and incident on the second surface of the polarization beam splitter 72, 60% of the S-polarized pulsed laser light is reflected by the second surface of the polarization beam splitter 72. The S-polarized pulsed laser light reflected by the second surface of the polarization beam splitter 72 is output from the dual-path OPS 70 as the second pulsed laser light that has made two turns in the delay optical path.

[0169] The second pulse laser is outputted after being delayed by a delay time Δt2 from the first pulse laser. OPS3 When the speed of light is c, Δt2 can be expressed as Δt2 = 2×L OPS3 / c.

[0170] 40% of the S-polarized pulsed laser light reflected by the concave mirror 64 d and incident on the second surface of the polarization beam splitter 72 passes through the polarization beam splitter 72 and enters the delay optical path.

[0171] Then, by repeatedly looping the light around the delay optical path, the third to n-th pulse laser lights are output from the dual-path OPS 70 .

[0172] Figure 11 : is a diagram showing the optical paths of the first pulse laser and the second pulse laser output from the dual-path OPS70. Figure 11 , the concave mirror 64a, the concave mirror 64b, the concave mirror 64c, and the concave mirror 64d are replaced by the convex lens 65a, the convex lens 65b, the convex lens 65c, and the convex lens 65d, respectively, each having a focal length of F2.

[0173] Figure 11 P0 represents the position of the polarization beam splitter 72. Figure 11 P1, P2, P3 and P4 respectively represent the positions of concave mirror 64a, concave mirror 64b, concave mirror 64c and concave mirror 64d. Figure 11 P11 and P12 respectively denote a position where the first transfer image is transferred and a position where the third transfer image is transferred.

[0174] Figure 11 F11A shown represents the first pulse laser, Figure 11 The F11B shown represents the second pulse laser. Figure 11 As shown, the optical path length difference between the first pulse laser and the second pulse laser is 2×L OPS3 =16F2.

[0175] 4.3 Action / Effect

[0176] In the dual-path OPS 70, S-polarized pulsed laser light, which is reflected by polarization beam splitter 72 and enters the delay optical path, is converted into P-polarized pulsed laser light by reflecting twice by quarter-wavelength mirrors 74a and 74b. This converts the pulsed laser light, which has made one circuit through the delay optical path and returned to polarization beam splitter 72, into P-polarized pulsed laser light. This then transmits the pulsed laser light through polarization beam splitter 72 and then again through the delay optical path. As a result, the optical propagation distance within the dual-path OPS 70 is approximately twice the optical path length of the conventional OPS 60, which also employs four concave mirrors 64. This allows for the expansion of pulse width while saving space.

[0177] In addition, the image in the polarization beam splitter 72 is transferred 1:1 at a position between the high reflection mirror 76a and the high reflection mirror 76b, and the image is transferred again 1:1 at the position of the polarization beam splitter 72, so that the pulse width can be extended without expanding the beam diameter of the pulse laser.

[0178] Furthermore, the optical path within the dual-path OPS70 is configured to travel in one direction, so the light that returns to the beam splitter after looping through the delay optical path does not return to the input side. Therefore, the return light does not adversely affect the resonators of PO30 and MO10.

[0179] Furthermore, the quarter-wavelength mirror has an advantage of excellent durability in the wavelength band of ArF laser light.

[0180] 5. Implementation Method 2

[0181] A description will be given of a dual-path OPS 80 according to Embodiment 2. Hereinafter, the same components as those of the OPS 70 are denoted by the same reference numerals, and detailed description thereof will be omitted.

[0182] 5.1 Structure

[0183] Figure 12 : is a diagram showing the structure of the dual path OPS80 of the second embodiment. Figure 12 As shown, the dual-path OPS 80 includes a polarization beam splitter 72 , a transfer optical system 73 , and an optical plate 78 .

[0184] The transfer optical system 73 includes a first transfer optical system 77a and a second transfer optical system 77b. The first transfer optical system 77a includes a quarter wavelength mirror 74a and a high reflection mirror 76a. The second transfer optical system 77b includes a quarter wavelength mirror 74b and a high reflection mirror 76b.

[0185] Concave mirror 64a and concave mirror 64b are arranged so that the pulsed laser light reflected by polarization beam splitter 72 is reflected by concave mirror 64a and incident on concave mirror 64b. Concave mirror 64b is arranged so that the pulsed laser light reflected by concave mirror 64b is incident on quarter wavelength mirror 74a.

[0186] The quarter-wavelength mirror 74a and the high-reflection mirror 76a are arranged so that the pulsed laser light reflected by the concave mirror 64b is reflected by the quarter-wavelength mirror 74a and enters the high-reflection mirror 76a. Furthermore, the high-reflection mirror 76a is arranged so that the pulsed laser light reflected by the quarter-wavelength mirror 74a enters the quarter-wavelength mirror 74a and enters the polarization beam splitter 72 again.

[0187] The concave mirror 64 d and the concave mirror 64 c are arranged so that the pulsed laser light reflected by the concave mirror 64 a and transmitted through the polarization beam splitter 72 is reflected by the concave mirror 64 d and enters the concave mirror 64 c .

[0188] The quarter-wavelength mirror 74b and the high-reflection mirror 76b are arranged so that the pulsed laser light reflected by the concave mirror 64c is reflected by the quarter-wavelength mirror 74b and enters the high-reflection mirror 76b. Furthermore, the high-reflection mirror 76b is arranged so that the pulsed laser light reflected by the quarter-wavelength mirror 74b is incident on the quarter-wavelength mirror 74b and enters the polarization beam splitter 72 again.

[0189] The distances between the polarization beam splitter 72 and the concave mirror 64a and the distance between the polarization beam splitter 72 and the concave mirror 64d are equal to the focal length F2. The distances between the concave mirrors 64a and 64b and the distance between the concave mirrors 64c and 64d are each twice the focal length F2. Furthermore, the distances along the optical path between the concave mirror 64b and the high-reflection mirror 76a and the distances along the optical path between the concave mirror 64c and the high-reflection mirror 76b are equal to the focal length F2.

[0190] The concave mirror 64 a , the concave mirror 64 b , and the quarter-wavelength mirror 74 a are configured to transfer the image on the first surface of the polarization beam splitter 72 to the first image at the high reflection mirror 76 a in a 1:1 ratio.

[0191] The high reflection mirror 76 a , the quarter-wavelength mirror 74 a , the concave mirror 64 b , and the concave mirror 64 a are configured to transfer the first image to the second image on the first surface of the polarization beam splitter 72 at a 1:1 ratio.

[0192] The concave mirror 64d, the concave mirror 64c, and the quarter-wavelength mirror 74b are configured to transfer the image on the first surface of the polarization beam splitter 72 to a third image at a 1:1 ratio on the high reflection mirror 76b.

[0193] The high reflection mirror 76 b , the quarter-wavelength mirror 74 b , the concave mirror 64 c , and the concave mirror 64 d are configured to transfer the third image to the second surface of the polarization beam splitter 72 as a fourth image at a 1:1 ratio.

[0194] 5.1.1 Configuration of 1 / 4 Wavelength Mirror and High Reflection Mirror

[0195] The optical path from the quarter-wavelength mirror 74 a to the high-reflection mirror 76 a is configured to form an angle of 45 degrees with respect to the optical path to the quarter-wavelength mirror 74 a .

[0196] Figure 13 yes Figure 12 The F-direction view in Figure 13 As shown, the high reflective mirror 76a is Figure 13 The quarter-wavelength mirror 74a is arranged at an angle of 45 degrees from the horizontal direction shown on the optical plate 78 side. The quarter-wavelength mirror 74a bends the optical path of the pulsed laser light at an angle of 45 degrees toward the optical plate 78 side and toward the high-reflection mirror 76a.

[0197] The optical path from the quarter-wavelength mirror 74 b to the high-reflection mirror 76 b is similarly configured to form an angle of 45 degrees with respect to the optical path to the quarter-wavelength mirror 74 b .

[0198] In addition, the positional relationship between the 1 / 4 wavelength mirror 74a and the high reflection mirror 76a is not limited to Figure 13 In the example shown, the quarter-wavelength mirror 74 a may bend the optical path of the pulsed laser light at an angle of 45 degrees toward the optical plate 78 and toward the high-reflection mirror 76 a .

[0199] 5.2 Action

[0200] The operation of the dual-path OPS80 will be described. An S-polarized pulsed laser beam is incident on the dual-path OPS80.

[0201] The S-polarized pulsed laser light incident on the dual-path OPS 80 is incident on the first surface of the polarization beam splitter 72. 40% of the S-polarized pulsed laser light transmitted through the polarization beam splitter 72 is output from the dual-path OPS 80 as the first pulsed laser light of zero-surround light that is not surrounded by the delay optical path.

[0202] 60% of the S-polarized pulsed laser light reflected by the polarization beam splitter 72 is reflected by the concave mirrors 64 a and 64 b and enters the quarter-wavelength mirror 74 a.

[0203] The quarter-wavelength mirror 74a converts the incident pulsed laser light into circularly polarized pulsed laser light. The circularly polarized pulsed laser light enters the high-reflection mirror 76a. The pulsed laser light image reflected by the polarization beam splitter 72 is transferred to the high-reflection mirror 76a as a 1:1 primary transfer image.

[0204] The high reflection mirror 76 a reflects the incident pulse laser light at a high reflectivity without changing its phase, and causes the laser light to be incident on the quarter wavelength mirror 74 a again.

[0205] Quarter-wavelength mirror 74a converts the circularly polarized pulsed laser light incident from high-reflection mirror 76a into P-polarized pulsed laser light. The P-polarized pulsed laser light enters concave mirror 64b, is reflected by both concave mirror 64b and concave mirror 64a, and enters the first surface of polarization beam splitter 72. At this point, the pulsed laser light has completed one rotation along the delayed optical path. The primary transfer image is transferred to the first surface of polarization beam splitter 72 as a 1:1 secondary transfer image.

[0206] The P-polarized pulsed laser light reflected by the concave mirror 64a and incident on the first surface of the polarization beam splitter 72 is transmitted by the polarization beam splitter 72 at approximately 100%, enters the second-turn delay optical path, and is incident on the concave mirror 64d.

[0207] The P-polarized pulse laser light incident on the concave mirror 64 d is reflected by the concave mirror 64 d and the concave mirror 64 c and is incident on the quarter-wavelength mirror 74 b .

[0208] The quarter-wavelength mirror 74b converts the incident pulsed laser light into circularly polarized pulsed laser light. The circularly polarized pulsed laser light enters the high-reflection mirror 76b. The secondary transfer image is transferred to the high-reflection mirror 76b as a 1:1 tertiary transfer image.

[0209] The high reflection mirror 76 b reflects the incident pulse laser light at a high reflectivity without changing its phase, and causes the laser light to enter the quarter wavelength mirror 74 b again.

[0210] Quarter-wavelength mirror 74b converts the circularly polarized pulsed laser light incident from high-reflection mirror 76b into P-polarized pulsed laser light. The P-polarized pulsed laser light enters concave mirror 64c, is reflected by concave mirrors 64c and 64d, and enters the second surface of polarization beam splitter 72. At this point, the pulsed laser light has completed two rotations along the delayed optical path. The third transfer image is transferred to the second surface of polarization beam splitter 72 as a 1:1 fourth transfer image.

[0211] Thus, the optical path for transferring the image of the input pulsed laser light on the first surface of the polarization beam splitter 72 as a first transfer image on the high reflective mirror 76a and the optical path for transferring the second transfer image on the first surface of the polarization beam splitter 72 as a third transfer image on the high reflective mirror 76b are symmetrical with respect to the optical path of the output pulsed laser light. Furthermore, it is preferable that the optical path for transferring the image of the input pulsed laser light on the first surface of the polarization beam splitter 72 as a first transfer image on the high reflective mirror 76a and the optical path for transferring the second transfer image on the first surface of the polarization beam splitter 72 as a third transfer image on the high reflective mirror 76b be arranged to be linearly symmetrical about the optical path of the output pulsed laser light as an axis of symmetry.

[0212] Of the S-polarized pulsed laser light reflected by the concave mirror 64 d and incident on the second surface of the polarization beam splitter 72, 60% of the S-polarized pulsed laser light is reflected by the second surface of the polarization beam splitter 72. The S-polarized pulsed laser light reflected by the second surface of the polarization beam splitter 72 is output from the dual-path OPS 80 as the second pulsed laser light that has made two turns in the delay optical path.

[0213] The second pulse laser is outputted after being delayed by a delay time Δt3 from the first pulse laser. OPS4 When the speed of light is c, Δt3 can be expressed as Δt3 = 2×L OPS4 / c.

[0214] 40% of the S-polarized pulsed laser light reflected by the concave mirror 64 d and incident on the second surface of the polarization beam splitter 72 passes through the polarization beam splitter 72 and enters the delay optical path.

[0215] Then, by repeatedly looping the light around the delay optical path, the third to n-th pulse laser lights are output from the dual-path OPS80.

[0216] Figure 14 : is a diagram showing the optical paths of the first pulse laser and the second pulse laser output from the dual-path OPS80. Figure 11 The same parts are denoted by the same reference numerals and detailed description thereof is omitted.

[0217] exist Figure 14 In FIG. 1 , F14A shows the first pulse laser, and F14B shows the second pulse laser. Figure 14 As shown, the optical path length difference between the first pulse laser and the second pulse laser is 2×L OPS4 =16F2.

[0218] 5.3 Action / Effect

[0219] In the dual-path OPS80, S-polarized pulsed laser light, after reflecting from the polarization beam splitter 72, is converted into P-polarized pulsed laser light by reflecting twice on the quarter-wavelength mirror 74a. The pulsed laser light then returns to the polarization beam splitter 72, passing through it and reflecting twice on the quarter-wavelength mirror 74b. As a result, the optical propagation distance within the dual-path OPS80 is approximately twice the optical path length of the conventional OPS60, which also employs four concave mirrors 64. This allows for increased pulse width while saving space.

[0220] Figure 15 : is a diagram showing the simulation results of the pulse waveform expansion of the output pulse laser of the laser system 1 when the dual-path OPS80 is applied instead of the OPS60. Figure 15The input pulse laser of OPS50 and Figure 5 The simulation results of the pulse waveform expansion of the output pulse laser of the laser system 1 are shown. Here, the optical path length L of the delay of one turn of OPS50 is OPS1 The optical path length L of one turn of delay in OPS60 is 7m. OPS2 The optical path length L of one turn of delay of the dual-path OPS80 is 14m. OPS4 That is, the optical propagation distance of the dual-path OPS80 is 28m.

[0221] like Figure 15 As shown in the figure, the combination of the OPS50 and the dual-path OPS80 can extend the pulse width of the OPS50's input pulse laser, which has a pulse width of 40ns, to 234ns. Furthermore, replacing the OPS60 with the dual-path OPS80 can extend the pulse width from 171ns to 234ns. This can be expected to improve speckle contrast from 5.7% to 5.1%.

[0222] 6. Modification 1 of Implementation 2

[0223] 6.1 Structure

[0224] Figure 16 This is a partial top view of the dual-path OPS80 of the first modification of the second embodiment. Figure 16 , a portion holding the quarter wavelength mirror 74a, the quarter wavelength mirror 74b, the high reflection mirror 76a, and the high reflection mirror 76b is shown. Figure 17 yes Figure 16 1 is a partial side view of the dual path OPS 80. In addition, the same reference numerals are given to the same parts as those of the dual path OPS 80 of the second embodiment, and detailed description thereof will be omitted.

[0225] The dual-path OPS 80 includes an XYZ stage 90 and an angle-variable stage 91 .

[0226] The quarter-wavelength mirror 74a, the quarter-wavelength mirror 74b, the high-reflection mirror 76a, and the high-reflection mirror 76b are each held by a holding member 79. Each holding member 79 has a two-axis tilt adjustment mechanism.

[0227] Each holding member 79 is positioned on an angular table 91. The angular table 91 is configured to rotate about a rotation axis R1. The rotation axis R1 of the angular table 91 defines the position of each holding member 79 so that it coincides with the incident and outgoing optical axes of the quarter-wavelength mirrors 74a and 74b.

[0228] The angle varying stage 91 is placed on the XYZ stage 90. The XYZ stage 90 is configured to be movable in three directions perpendicular to each other.

[0229] 6.2 Action

[0230] The holding components 79, the XYZ stage 90, and the angle changing stage 91 are adjusted so that the S-polarized pulsed laser beam is incident on the 1 / 4 wavelength mirror 74a, is converted into a P-polarized pulsed laser beam, and is emitted from the 1 / 4 wavelength mirror 74a coaxially with the incident optical axis. At this time, the angle changing stage 91 is adjusted so that the optical axis between the 1 / 4 wavelength mirror 74a and the high reflection mirror 76a and the optical axis between the 1 / 4 wavelength mirror 74b and the high reflection mirror 76b are aligned with the axis of the incident light. Figure 16 The two directions perpendicular to the paper and along the paper form an angle of 45 degrees. An additional adjustment device may be configured to allow S-polarized pulsed laser light to be incident on the quarter-wavelength mirror 74a, and to monitor the output pulsed laser light from the quarter-wavelength mirror 74a using a polarimeter. Figure 18 It is a partial side view showing a state where the angle varying stage 91 is adjusted.

[0231] Next, the support surface of optical plate 78 is fixed and rotated 180 degrees, changing the orientation of the incident and outgoing optical axes of quarter-wavelength mirror 74a by 180 degrees. Next, the retaining components 79 and XYZ stage 90 are adjusted so that S-polarized pulsed laser light is incident on quarter-wavelength mirror 74b, converted into P-polarized pulsed laser light, and emitted from quarter-wavelength mirror 74b coaxially with the incident optical axis. Here, the angle adjustment stage 91 is set to the angle adjusted so that S-polarized pulsed laser light is incident on quarter-wavelength mirror 74a, and no further adjustment is performed.

[0232] This adjustment may be performed in advance at a factory or the like before combining with the excimer laser device 2 .

[0233] 6.3 Action / Effect

[0234] According to the OPS 80 of the first variation of the second embodiment, an adjustment mechanism using the holding member 79, the XYZ stage 90, and the variator 91 is provided. This allows the position and orientation of each optical element to be adjusted to suppress unwanted light caused by polarization errors. In particular, the variator 91 facilitates adjustment of the polarization rotation state.

[0235] 7. Modification 2 of Implementation 2

[0236] 7.1 Structure

[0237] Figure 19 This is a partial top view of the dual-path OPS80 of the second modification of the second embodiment. Figure 19 , a portion holding the quarter wavelength mirror 74b and the high reflection mirror 76b is shown. Figure 20 yes Figure 191 is a partial side view of the dual path OPS 80. Components identical to those of the dual path OPS 80 of the first modification of the second embodiment are denoted by the same reference numerals and detailed description thereof will be omitted.

[0238] The dual path OPS 80 includes an XYZ stage 90, an angular stage 91, and a rotation stage 92 for the secondary transfer optical system 77b. The secondary transfer optical system 77b is disposed on the angular stage 91. The angular stage 91 is mounted on the rotation stage 92. The rotation stage 92 is mounted on the XYZ stage 90.

[0239] The position of each holding member 79 is defined so that the rotation axis R1 of the variator 91 coincides with the incident and outgoing optical axis of the quarter-wavelength mirror 74 b .

[0240] The positions of the holding members 79 are determined so that the rotation axis R2 of the rotating stage 92 passes through the intersection of the incident and outgoing light axes of the quarter-wavelength mirror 74b with respect to the concave mirror 64c and the incident and outgoing light axes of the high reflection mirror 76b.

[0241] Although not shown here, the first transfer optical system 77a can also have a similar structure. In this case, the XYZ stage 90 on which the first transfer optical system 77a is mounted corresponds to the first XYZ stage, the angular table 91 corresponds to the first angular table, and the rotation stage 92 corresponds to the first rotation stage. Similarly, the XYZ stage 90 on which the second transfer optical system 77b is mounted corresponds to the second XYZ stage, the angular table 91 corresponds to the second angular table, and the rotation stage 92 corresponds to the second rotation stage.

[0242] 7.2 Action

[0243] The holding components 79, XYZ stage 90, angle changing stage 91 and rotation stage 92 are adjusted so that the S-polarized pulsed laser light incident on the 1 / 4 wavelength mirror 74b is converted into P-polarized pulsed laser light and emitted from the 1 / 4 wavelength mirror 74b coaxially with the incident optical axis. Figure 21 It is a partial side view showing a state where the angle varying stage 91 is adjusted.

[0244] The first transfer optical system 77a is also adjusted in the same manner.

[0245] 7.3 Action / Effect

[0246] According to the second modification of the second embodiment, the first transfer optical system 77a and the second transfer optical system 77b can be adjusted independently, so the degree of adjustment freedom is high and correction of polarization errors caused by mechanical errors of the dual-path OPS 80 is easy.

[0247] Furthermore, Modification 1 of Embodiment 2 and Modification 2 of Embodiment 2 can also be applied to Embodiment 1 by changing the postures of the high-reflection mirror 76 a and the high-reflection mirror 76 b .

[0248] 8. Modification 3 of Implementation 2

[0249] 8.1 Structure

[0250] Figure 22 FIG. 1 is a top view of a 45-degree right-angle prism element 94 according to a third variation of the second embodiment. Figure 22 As shown, the 45-degree right angle prism element 94 includes a prism portion 95 , a quarter wavelength mirror film 96 , a reflection suppression film 97 , and a high reflection film 98 .

[0251] The prism portion 95 has a triangular prism shape of an isosceles right triangle in a plan view. The material of the prism portion 95 includes at least one of CaF 2 and SiO 2 .

[0252] The quarter-wavelength mirror film 96 is provided on the side of the triangular prism-shaped prism portion 95 that forms the hypotenuse of the isosceles right triangle. The anti-reflection film 97 is provided on the side of the triangular prism-shaped prism portion 95 that forms one right-angled side of the isosceles right triangle. The high-reflection film 98 is provided on the side of the triangular prism-shaped prism portion 95 that forms the other right-angled side of the isosceles right triangle.

[0253] The 45-degree right-angle prism element 94 can be applied to both the first transfer optical system 77a and the second transfer optical system 77b. For example, when the 45-degree right-angle prism element 94 is applied to the first transfer optical system 77a, the quarter-wavelength mirror film 96 can function similarly to the quarter-wavelength mirror 74a, and the high-reflection film 98 can function similarly to the high-reflection mirror 76a.

[0254] The 45-degree right angle prism element 94 can be fixed to a holding member 79 (see FIG. 1 ) which can be rotated about the incident and outgoing light axis of the 1 / 4 wavelength mirror film 96. Figure 13 ), it can also be fixed to the angle table 91 (refer to Figure 16 ).

[0255] 8.2 Action

[0256] Pulsed laser light is incident on the 45-degree right-angle prism element 94 from the surface provided with the reflection-reducing film 97. Quarter-wavelength mirror film 96 is tilted 45 degrees relative to the electric field vibration axis of the incident light. This imparts a quarter-wavelength phase modulation to each polarization component of the incident light, converting linear polarization into circular polarization. The circularly polarized pulsed laser light is incident on the high-reflection film 98.

[0257] The pulsed laser light converted into circular polarization is reflected by the high reflective film 98 at a high reflectivity without changing its phase, and enters the ¼ wavelength mirror film 96 again.

[0258] The high reflection film 98 reflects the incident pulse laser light at a high reflectivity without changing the wavefront, and the laser light is incident on the quarter-wavelength mirror film 96 again.

[0259] Quarter-wavelength mirror film 96 further phase-modulates each polarization component of the circularly polarized pulsed laser light incident from high-reflection film 98 by a quarter wavelength, converting the circularly polarized pulsed laser light into linearly polarized pulsed laser light. The converted linearly polarized pulsed laser light enters reflection suppression film 97 and exits from 45-degree right-angle prism element 94.

[0260] 8.3 Action / Effect

[0261] The 45-degree right-angle prism element 94 can convert linear polarization into circular polarization by the first reflection at the quarter-wavelength mirror film 96, and rotate the polarization direction 90 degrees by the second reflection. The 45-degree right-angle prism element 94 can integrally form the quarter-wavelength mirror film 96 and the high-reflection film 98, making position adjustment easier.

[0262] 9. Implementation Method 3

[0263] The dual-path OPS 100 according to Embodiment 3 will be described. Components identical to those of the dual-path OPS 80 according to Embodiment 2 are denoted by the same reference numerals, and detailed description thereof will be omitted.

[0264] 9.1 Structure

[0265] Figure 23 FIG is a diagram showing the structure of the dual-path OPS 100. Figure 23 As shown, the dual-path OPS100 includes eight concave mirrors 64 .

[0266] Eight concave mirrors 64 (an example of a plurality of concave mirrors) form a delay optical path for extending the pulse width of the pulsed laser light. The eight concave mirrors 64 consist of concave mirror 64a, concave mirror 64b, concave mirror 64c, concave mirror 64d, concave mirror 64e, concave mirror 64f, concave mirror 64g, and concave mirror 64h. All eight concave mirrors 64 have a focal length of F2.

[0267] Concave mirrors 64a, 64b, 64h, and 64g are arranged so that the pulsed laser light reflected by the polarization beam splitter 72 is reflected by concave mirrors 64a, 64b, 64h, and 64g in sequence and enters the quarter-wavelength mirror 74a.

[0268] Concave mirror 64d, concave mirror 64c, concave mirror 64e and concave mirror 64f are configured so that the pulsed laser light reflected by concave mirror 64a and transmitted through polarization beam splitter 72 is reflected by concave mirror 64d, concave mirror 64c, concave mirror 64e and concave mirror 64f in sequence and enters 1 / 4 wavelength mirror 74b.

[0269] The distance between the polarization beam splitter 72 and the concave mirror 64a, and the distance between the concave mirror 64d and the polarization beam splitter 72 are equal to the focal length F2. The distance between the concave mirrors 64a and 64b, the distance between the concave mirrors 64b and 64h, the distance between the concave mirrors 64h and 64g, the distance between the concave mirrors 64d and 64c, the distance between the concave mirrors 64c and 64e, and the distance between the concave mirrors 64e and 64f are each twice the focal length F2. Furthermore, the distance on the optical path between the concave mirror 64g and the high-reflection mirror 76a, and the distance on the optical path between the concave mirror 64f and the high-reflection mirror 76b are equal to the focal length F2.

[0270] Concave mirrors 64a, 64b, 64h, and 64g are configured to transfer the image of the first surface of the polarization beam splitter 72 to the high-reflection mirror 76a at a 1:1 ratio. Concave mirrors 64d, 64c, 64e, and 64f are configured to transfer the image of the first surface of the polarization beam splitter 72 to the high-reflection mirror 76b at a 1:1 ratio.

[0271] Assume that the length of one circle of the delay optical path of the dual-path OPS100 is L OPS5 When L OPS5 =16F2.

[0272] 9.2 Action

[0273] The operation of the dual path OPS 100 will be described. S-polarized pulsed laser light is incident on the dual path OPS 100. 40% of the S-polarized pulsed laser light that passes through the polarization beam splitter 72 is output from the dual path OPS 100 as the first pulsed laser light of zero-surround light that is not surrounded by the delay optical path.

[0274] After being reflected by polarization beam splitter 72, 60% of the S-polarized pulsed laser light is reflected by concave mirrors 64a, 64b, 64h, and 64g, and enters primary transfer optical system 77a. The pulsed laser light image reflected by polarization beam splitter 72 is transferred to a 1:1 primary transfer image by high-reflection mirror 76a.

[0275] The pulsed laser light converted to P polarization in primary transfer optical system 77a is reflected by concave mirrors 64g, 64h, 64b, and 64a, and enters the first surface of polarization beam splitter 72. At this point, the pulsed laser light has completed one rotation along the delayed optical path. The primary transfer image is transferred to the first surface of polarization beam splitter 72 as a 1:1 secondary transfer image.

[0276] The P-polarized pulsed laser light reflected by the concave mirror 64a and incident on the first surface of the polarization beam splitter 72 is transmitted by the polarization beam splitter 72 at approximately 100%, enters the second-turn delay optical path, and is incident on the concave mirror 64d.

[0277] The P-polarized pulsed laser beam incident on the concave mirror 64d is reflected by the concave mirrors 64d, 64c, 64e, and 64f and enters the secondary transfer optical system 77b. The secondary transfer image is transferred to a 1:1 third transfer image by the high reflection mirror 76b.

[0278] The pulsed laser light, converted to S-polarization in the secondary transfer optical system 77b, enters concave mirror 64f, is reflected by concave mirrors 64f, 64e, 64c, and 64d, and enters the second surface of polarization beam splitter 72. At this point, the pulsed laser light has completed two rotations along the delayed optical path. The third transfer image is transferred to the second surface of polarization beam splitter 72 as a fourth transfer image at a 1:1 ratio.

[0279] Of the S-polarized pulsed laser light reflected by the concave mirror 64 d and incident on the second surface of the polarization beam splitter 72, 60% of the S-polarized pulsed laser light is reflected by the second surface of the polarization beam splitter 72. The S-polarized pulsed laser light reflected by the second surface of the polarization beam splitter 72 is output from the dual-path OPS 100 as the second pulsed laser light that has made two turns along the delay optical path.

[0280] The second pulse laser is outputted after being delayed by a delay time Δt4 from the first pulse laser. OPS5 When the speed of light is c, Δt4 can be expressed as Δt4 = 2×L OPS5 / c.

[0281] Then, by repeatedly looping the light around the delay optical path, the third to n-th pulse laser lights are output from the dual-path OPS 100 .

[0282] 9.3 Action / Effect

[0283] By adding the concave mirror 64e, the concave mirror 64f, the concave mirror 64g, and the concave mirror 64h to the dual-path OPS 80, the optical path length for optical delay can be extended.

[0284] 10. Method for manufacturing electronic devices

[0285] Figure 24 300 is a diagram schematically showing a configuration example of the exposure apparatus 302. The method for manufacturing an electronic device is realized by the excimer laser apparatus 2, the pulse width stretching apparatus 300, and the exposure apparatus 302.

[0286] The pulse laser light output from the excimer laser device 2 is input to the pulse width stretching device 300. The pulse width stretching device 300 may include at least one of the dual-path OPS 70, the dual-path OPS 80, and the dual-path OPS 100 described in each embodiment.

[0287] The pulse laser light having its pulse width expanded is generated by the excimer laser device 2 and the pulse width expansion device 300. The pulse laser light having its pulse width expanded is input to the exposure device 302 and used as exposure light.

[0288] The exposure device 302 includes an illumination optical system 304 and a projection optical system 306. The illumination optical system 304 illuminates the mask pattern of the mask stage RT by the pulse laser incident from the pulse width expansion device 3. The projection optical system 306 performs a reduced projection of the pulse laser that passes through the mask so that it is imaged on a workpiece (not shown) arranged on the workpiece stage WT. The workpiece is a photosensitive substrate such as a semiconductor wafer coated with photoresist. The exposure device 302 moves the mask stage RT and the workpiece stage WT synchronously and parallely, thereby exposing the workpiece to the pulse laser that reflects the mask pattern. By transferring the device pattern on the semiconductor wafer through the above exposure process, a semiconductor device can be manufactured. A semiconductor device is an example of an "electronic device" in the present disclosure.

[0289] 11. Others

[0290] As the excimer laser device MO10 2 , an excimer laser device is used, but a solid-state laser device may also be used.

[0291] The above description is not limiting but merely illustrative. Therefore, those skilled in the art will appreciate that modifications can be made to the embodiments of the present disclosure without departing from the scope of the claims. Furthermore, those skilled in the art will appreciate that combinations of the embodiments of the present disclosure can be used.

[0292] Unless otherwise expressly stated, the terms used in this specification and claims as a whole should be interpreted as “non-limiting” terms. For example, terms such as “including” or “comprising” should be interpreted as “not limited to the parts recorded as included”. Terms such as “having” should be interpreted as “not limited to the parts recorded as having”. In addition, the indefinite article “a” should be interpreted as meaning “at least one” or “one or more”. In addition, terms such as “at least one of A, B and C” should be interpreted as “A”, “B”, “C”, “A+B”, “A+C”, “B+C” or “A+B+C”. Furthermore, it should be interpreted as also including combinations of these and parts other than “A”, “B” and “C”.

Claims

1. A pulse width extension device, comprising: a polarization beam splitter that transmits pulsed laser light in a first polarization direction among linearly polarized pulsed laser light at a first transmittance, and reflects pulsed laser light in a second polarization direction orthogonal to the first polarization direction at a first reflectivity and transmits the same at a second transmittance; and a transfer optical system that causes the pulsed laser light reflected by the polarization beam splitter to be reflected by a plurality of concave mirrors and returned to the polarization beam splitter; The polarization beam splitter combines and outputs the pulsed laser light of the second polarization direction transmitted at the second transmittance among the pulsed laser light input from the outside and a portion of the pulsed laser light returned from the transfer optical system. The transfer optical system comprises: a quarter-wavelength mirror pair comprising a first quarter-wavelength mirror that reflects the pulsed laser light while shifting its phase by a quarter of a wavelength, and a second quarter-wavelength mirror that reflects the pulsed laser light after being reflected by the first quarter-wavelength mirror while shifting its phase by a quarter of a wavelength; and A pair of reflectors is arranged in the optical path before and after the quarter-wavelength mirror pair or in the optical path between the quarter-wavelength mirror pair. The transfer optical system transfers the image of the input pulse laser in the polarization beam splitter into a first transfer image at equal magnification on the optical path between the 1 / 4 wavelength mirror pair, and transfers the first transfer image into a second transfer image at equal magnification in the polarization beam splitter.

2. The pulse width stretching device according to claim 1, wherein: The reflector pair comprises a first reflector and a second reflector, The first reflector, which is one of the mirrors in the reflector pair, will reflect the pulsed laser light reflected by the first 1 / 4 wavelength mirror, which is one of the mirrors in the 1 / 4 wavelength mirror pair, toward the second reflector, which is the other mirror in the reflector pair, and the second reflector will reflect the pulsed laser light reflected by the first reflector toward the second reflector toward the second 1 / 4 wavelength mirror, which is the other mirror in the 1 / 4 wavelength mirror pair.

3. The pulse width stretching device according to claim 2, wherein: The transfer optical system transfers the first transfer image between the first reflecting mirror and the second reflecting mirror.

4. The pulse width stretching device according to claim 2, wherein: The first quarter-wavelength mirror and the second quarter-wavelength mirror bend the optical path of the pulsed laser at an angle of 45 degrees.

5. The pulse width stretching device according to claim 1, wherein: The pulse width expansion device includes an angle changing stage on which the quarter wavelength mirror pair and the reflecting mirror pair are placed. The angular stage sets the incident and outgoing light axes of the quarter-wavelength mirror pair as the rotation axis.

6. The pulse width stretching device according to claim 5, wherein: The pulse width expansion device has an XYZ stage that can move in three directions orthogonal to each other. The angular variation stage is placed on the XYZ stage.

7. The pulse width stretching device according to claim 2, wherein: The pulse width expansion device comprises: a first angular stage, on which the first quarter-wavelength mirror and the first reflecting mirror are mounted; a second angular stage on which the second quarter-wavelength mirror and the second reflecting mirror are mounted; The first angular stage sets the incident and outgoing light axes of the first quarter-wavelength mirror as the rotation axis. The second angular variation stage uses the incident and outgoing light axes of the second quarter-wavelength mirror as a rotation axis.

8. The pulse width stretching device according to claim 7, wherein: The pulse width expansion device comprises: a first rotating platform on which the first angle-changing platform is mounted; as well as a second rotating platform on which the second angle changing platform is mounted; The first rotating stage has a rotating axis passing through the intersection of the incident and outgoing light axes of the first quarter-wavelength mirror and the incident and outgoing light axes of the first reflecting mirror. The second rotating stage has a rotation axis passing through an intersection of an incident and outgoing light axis of the second quarter-wavelength mirror and an incident and outgoing light axis of the second reflecting mirror.

9. The pulse width stretching device according to claim 1, wherein: The polarization beam splitter is configured to be tilted 45 degrees with respect to the optical axis of the input pulse laser light.

10. The pulse width stretching device according to claim 9, wherein: The quarter-wavelength mirror pair converts the second polarization direction of the pulsed laser light reflected by the polarization beam splitter into the first polarization direction and outputs the polarization direction. The polarization beam splitter transmits the pulsed laser light in the first polarization direction returned from the transfer optical system at a first transmittance and causes the pulsed laser light to enter the transfer optical system again.

11. The pulse width stretching device according to claim 10, wherein: The quarter-wavelength mirror pair converts the first polarization direction of the pulsed laser light that has passed through the polarization beam splitter at the first transmittance and is incident on the transfer optical system again into the second polarization direction and outputs the pulsed laser light. The polarization beam splitter reflects the pulsed laser light in the second polarization direction returned from the transfer optical system at the first reflectivity and outputs the reflected laser light.

12. The pulse width stretching device according to claim 11, wherein: In the transfer optical system, the optical path for transferring the image of the input pulse laser in the polarization beam splitter into the first transfer image and the optical path for transferring the first transfer image into the second transfer image in the polarization beam splitter are configured to be linearly symmetrical with the optical path of the output pulse laser output by the polarization beam splitter as the axis of symmetry.

13. The pulse width stretching device according to claim 1, wherein: The plurality of concave mirrors respectively have the same focal length.

14. The pulse width stretching device according to claim 1, wherein: The pulse laser is ArF laser.

15. A method for manufacturing an electronic device, comprising the following steps: The laser system generates pulsed laser light with pulse width expanded. Outputting the pulse laser to an exposure device, exposing the pulsed laser light on a photosensitive substrate in the exposure device to manufacture electronic devices, The laser system comprises a laser device and a pulse width expansion device. The laser device generates linearly polarized pulsed laser light. The pulse width stretching device has: a polarization beam splitter that transmits pulsed laser light in a first polarization direction among linearly polarized pulsed laser light at a first transmittance, and reflects pulsed laser light in a second polarization direction orthogonal to the first polarization direction at a first reflectivity and transmits the same at a second transmittance; and a transfer optical system that causes the pulsed laser light reflected by the polarization beam splitter to be reflected by a plurality of concave mirrors and returned to the polarization beam splitter; The polarization beam splitter combines and outputs the pulsed laser light of the second polarization direction transmitted at the second transmittance among the pulsed laser light input from the outside and a portion of the pulsed laser light returned from the transfer optical system. The transfer optical system comprises: a quarter-wavelength mirror pair comprising a first quarter-wavelength mirror that reflects the pulsed laser light while shifting its phase by a quarter of a wavelength, and a second quarter-wavelength mirror that reflects the pulsed laser light after being reflected by the first quarter-wavelength mirror while shifting its phase by a quarter of a wavelength; and A pair of reflectors is arranged in the optical path before and after the quarter-wavelength mirror pair or in the optical path between the quarter-wavelength mirror pair. The transfer optical system transfers the image of the input pulse laser in the polarization beam splitter into a first transfer image at equal magnification on the optical path between the 1 / 4 wavelength mirror pair, and transfers the first transfer image into a second transfer image at equal magnification in the polarization beam splitter.

16. A pulse width extension device comprising: a polarization beam splitter that transmits pulsed laser light in a first polarization direction among the linearly polarized pulsed laser light at a first transmittance, and reflects pulsed laser light in a second polarization direction orthogonal to the first polarization direction at a first reflectivity and transmits the same at a second transmittance; as well as a transfer optical system that causes the pulsed laser light reflected by the polarization beam splitter to be reflected by a plurality of concave mirrors and returned to the polarization beam splitter; The polarization beam splitter combines and outputs the pulsed laser light of the second polarization direction transmitted at the second transmittance among the pulsed laser light input from the outside and a portion of the pulsed laser light returned from the transfer optical system. The transfer optical system comprises: A first transfer optical system comprising a first quarter-wavelength mirror that reflects the pulsed laser light while shifting its phase by 1 / 4 wavelength; and a first reflecting mirror that reflects the pulsed laser light reflected by the first quarter-wavelength mirror toward the first quarter-wavelength mirror so that the pulsed laser light reflected by the first quarter-wavelength mirror is incident on the first quarter-wavelength mirror again. as well as A second transfer optical system including a second quarter-wavelength mirror that shifts the phase of the pulsed laser light by a quarter of its wavelength and reflects the pulsed laser light; and reflecting the pulsed laser light reflected by the second quarter wavelength mirror toward the second quarter wavelength mirror so that the pulsed laser light reflected by the second quarter wavelength mirror is incident on the second reflecting mirror of the second quarter wavelength mirror again. The first transfer optical system transfers the image of the input pulse laser in the polarization beam splitter into a first transfer image at the same magnification on the first reflection mirror, and transfers the first transfer image into a second transfer image at the same magnification on the polarization beam splitter. The second transfer optical system transfers the second transfer image to a third transfer image at the same magnification on the second reflecting mirror, and transfers the third transfer image to a fourth transfer image at the same magnification on the polarization beam splitter.

17. The pulse width stretching device according to claim 16, wherein: At least one of the first transfer optical system and the second transfer optical system includes a 45-degree right-angle prism element. The 45-degree right-angle prism element has: A quarter-wavelength mirror film that forms a quarter-wavelength mirror on a side surface including a right-angled hypotenuse; and A reflective film forms a reflector on a side surface including one of the right angle sides of the right angle.

18. The pulse width stretching device according to claim 17, wherein: The 45-degree right angle prism element has a reflection suppression film on a side surface of the other right angle side including the right angle.

19. The pulse width stretching device according to claim 18, wherein: The 45-degree right-angle prism element is fixed so as to be rotatable about the incident and outgoing light axis of the 1 / 4 wavelength mirror film.

20. The pulse width stretching device according to claim 16, wherein: In the transfer optical system, the optical path for transferring the image of the input pulse laser in the polarization beam splitter into the first transfer image and the optical path for transferring the second transfer image into the third transfer image are configured to be linearly symmetrical with the optical path of the output pulse laser output by the polarization beam splitter as the axis of symmetry.

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