Laser device and method of manufacturing electronic device

Abstract

The present application provides a laser device and a manufacturing method of an electronic device, the laser device according to one aspect includes: a discharge excitation type laser oscillator which outputs pulsed laser in an ultraviolet wavelength region; a first optical pulse stretcher which includes a beam splitter and a plurality of concave mirrors, and which expands a pulse width of the pulsed laser; and a relay lens which includes a first lens and a second lens arranged on an optical path of the pulsed laser after the pulse width is expanded, the first lens being a spherical plano-convex lens, and the second lens having a focal length in a long side direction of a beam cross section of the pulsed laser which is shorter than a focal length in a short side direction.

Description

Technical Field

[0001] This disclosure relates to methods for manufacturing laser devices and electronic components. Background Technology

[0002] In recent years, with the miniaturization and high integration of semiconductor integrated circuits, there has been a growing demand for higher resolution in semiconductor exposure equipment. Therefore, efforts are underway to shorten the wavelength of light emitted from exposure light sources. For example, KrF excimer laser devices using lasers with an output wavelength of approximately 248 nm and ArF excimer laser devices using lasers with an output wavelength of approximately 193 nm are examples of gas laser devices used for exposure.

[0003] The spectral linewidth of the naturally oscillating light from KrF and ArF excimer lasers is as wide as 350-400 pm. Therefore, if the projection lens is made of a material that transmits ultraviolet light, such as that used in KrF and ArF lasers, chromatic aberration will occur. As a result, the resolution may be reduced. Therefore, it is necessary to narrow the spectral linewidth of the laser output from the gas laser device to a level where chromatic aberration is negligible. Thus, in order to narrow the spectral linewidth, a line-narrowing module (LNM) containing narrowing elements (etalon, grating, etc.) is sometimes included in the laser resonator of a gas laser device. Hereinafter, gas laser devices with narrowed spectral linewidths will be referred to as narrow-bandgap gas laser devices.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: U.S. Patent Application Publication No. 2016 / 0248219

[0007] Patent Document 2: Japanese Patent Application Publication No. 2005-167082 Summary of the Invention

[0008] One aspect of this disclosure relates to a laser device comprising: a discharge-excited laser oscillator that outputs pulsed laser light in the ultraviolet wavelength region; a first optical pulse stretcher including a beam splitter and a plurality of concave mirrors for extending the pulse width of the pulsed laser light; and a relay lens comprising a first lens and a second lens disposed in the optical path of the pulsed laser light after the pulse width has been extended, the first lens being a plano-convex spherical lens, and the second lens having a shorter focal length in the long side direction of the beam cross-section of the pulsed laser light than in the short side direction.

[0009] One aspect of this disclosure relates to a method for manufacturing an electronic device, comprising: outputting a pulsed laser from a laser device to an exposure device, exposing a photosensitive substrate within the exposure device using the pulsed laser for the purpose of manufacturing the electronic device, wherein the laser device comprises: a discharge-excited laser oscillator that outputs a pulsed laser in the ultraviolet wavelength region; a first optical pulse stretcher comprising a beam splitter and a plurality of concave mirrors for extending the pulse width of the pulsed laser; and a relay lens comprising a first lens and a second lens disposed in the optical path of the pulsed laser after the pulse width has been extended, wherein the first lens is a spherical plano-convex lens, and the second lens has a shorter focal length in the long side direction of the beam cross-section of the pulsed laser than in the short side direction. Attached Figure Description

[0010] The following description, by way of example only, refers to the accompanying drawings to illustrate several embodiments of the present disclosure.

[0011] Figure 1 This is a diagram illustrating the beam divergence angle.

[0012] Figure 2 This is a diagram illustrating an example of the cross-sectional shape of a pulsed laser beam.

[0013] Figure 3 This is a diagram illustrating the relay lens.

[0014] Figure 4 This is a diagram showing the internal structure of the laser device involved in the comparative example as viewed from the front.

[0015] Figure 5 This is a diagram showing the internal structure of the laser device involved in the comparative example as viewed from above.

[0016] Figure 6 This is a diagram showing the internal structure of the laser device according to the first embodiment as viewed from the front.

[0017] Figure 7 This is a diagram showing the internal structure of the laser device according to the first embodiment as viewed from above.

[0018] Figure 8 This is a diagram showing the structure of the first lens.

[0019] Figure 9 This is a diagram showing the structure of the second lens.

[0020] Figure 10 This is a diagram showing the focal length of the second lens in the first and second directions.

[0021] Figure 11 It is a diagram representing the focal length of a convex cylindrical surface.

[0022] Figure 12This is a diagram illustrating the change in the beam divergence angle in the first direction.

[0023] Figure 13 This is a diagram of the optical path length changing mechanism viewed from the optical axis direction.

[0024] Figure 14 This is a diagram showing the optical path length changing mechanism viewed from the first direction.

[0025] Figure 15 This is a diagram showing the second lens according to the second embodiment.

[0026] Figure 16 It is a diagram showing the focal length of the second lens based on the first curvature and the focal length based on the second curvature.

[0027] Figure 17 This is a diagram that roughly illustrates an example of the structure of an exposure apparatus. Detailed Implementation

[0028] <Content>

[0029] 1. Explanation of terminology

[0030] 1.1 Beam divergence angle

[0031] 1.2 Relay Lens

[0032] 2. Comparative Example

[0033] 2.1 Structure

[0034] 2.2 Actions

[0035] 2.3 Research Topic

[0036] 3. First Implementation Method

[0037] 3.1 Structure

[0038] 3.2 Actions

[0039] 3.3 Effects

[0040] 4. Second Implementation Method

[0041] 4.1 Structure

[0042] 4.2 Actions

[0043] 4.3 Effects

[0044] 5. Variations

[0045] 6. Manufacturing methods for electronic devices

[0046] Hereinafter, various embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. The embodiments described below represent several examples of the present disclosure and do not limit the content of the present disclosure. Furthermore, the structures and operations described in each embodiment are not necessarily all necessary for the structures and operations of the present disclosure. In addition, the same reference numerals are used to denote the same constituent elements, and repeated descriptions are omitted.

[0047] 1. Explanation of terminology

[0048] 1.1 Beam divergence angle

[0049] Figure 1 The beam divergence angle is explained. For example... Figure 1 As shown, when the pulsed laser PL is focused using the condenser lens 100, the value obtained by dividing the size of the focused point formed at the focal length F by the focal length F of the condenser lens 100 is defined as the "beam divergence angle". Here, the size of the focused point is the diameter of the focused point or the entire width, which can be measured using a two-dimensional image sensor 101 or the like.

[0050] In this disclosure, reference numeral A denotes the optical axis of the optical system, and the pulsed laser PL travels along the optical axis A. Furthermore, the direction parallel to the optical axis A is referred to as the optical axis direction α. ​​The direction perpendicular to the optical axis direction α is designated as the first direction β, and the direction perpendicular to both the optical axis direction α and the first direction β is designated as the second direction γ.

[0051] The two-dimensional image sensor 101 has a light-receiving surface parallel to the first direction β and the second direction γ. That is, by measuring the size of the focusing point in the first direction β and the size of the focusing point in the second direction γ respectively, the beam divergence angle in the first direction β and the beam divergence angle in the second direction γ can be measured respectively.

[0052] Figure 2 An example illustrating the beam cross-sectional shape of a pulsed laser (PL). For example... Figure 2 As shown, the pulsed laser PL output from the discharge-excited laser device has a rectangular beam cross-section. The long side of this rectangle is the direction in which a pair of discharge electrodes face each other, i.e., the discharge direction, and the short side is the direction perpendicular to the discharge direction. In this disclosure, the discharge direction of the beam cross-section is defined as the first direction β, and the short side of the beam cross-section is defined as the second direction γ.

[0053] Thus, in a discharge-excited laser device, the cross-sectional shape of the pulsed laser PL is rectangular, so the beam divergence angle is different in the first direction β and the second direction γ. Usually, the beam divergence angle in the first direction β is greater than the beam divergence angle in the second direction γ.

[0054] 1.2 Relay Lens

[0055] Figure 3The relay lens is explained. For example... Figure 3 As shown, the relay lens 110 includes an upstream-side lens 100a and a downstream-side lens 100b arranged along the optical axis A. Figure 3 In the example shown, the upstream lens 100a and the downstream lens 100b are both spherical plano-convex lenses, arranged with their respective planes facing each other. Furthermore, the upstream lens 100a and the downstream lens 100b have the same focal length. Let this focal length be F.

[0056] Ideally, the upstream lens 100a and the downstream lens 100b are configured such that the rear focal position of the upstream lens 100a coincides with the front focal position of the downstream lens 100b. That is, the upstream lens 100a and the downstream lens 100b are configured with an optical path spacing of 2F. The beam cross-section shape of the pulsed laser PL at the front focal position of the upstream lens 100a is flipped at the rear focal position of the downstream lens 100b to form an image at a 1:1 ratio.

[0057] 2. Comparative Example

[0058] The comparative examples disclosed herein are those that the applicant recognizes as being known only to the applicant, and are not publicly known examples that the applicant himself endorses.

[0059] 2.1 Structure

[0060] Figure 4 and Figure 5 The structure of the laser device 2 involved in the comparative example is shown in general. Figure 4 This indicates a view of the internal structure of laser device 2 from the front. Figure 5 This indicates the internal structure of the laser device 2 as viewed from above.

[0061] exist Figure 4 and Figure 5 In this design, the height direction of the laser device 2 is defined as the V-axis, the length direction as the Z-axis, and the depth direction as the H-axis. For example, the V-axis is parallel to the direction of gravity. Furthermore, the Z-axis is parallel to the emission direction of the pulsed laser PL emitted from the laser device 2.

[0062] Laser device 2 is a discharge-excited narrowband gas laser device comprising a master oscillator (MO) 10, an MO beam steering unit 20, a power oscillator (PO) 30, a PO beam steering unit 40, first and second optical pulse stretchers (OPS) 50 and 60, a monitoring module 70, and a laser processor 80. The master oscillator 10 is an example of a "laser oscillator" as disclosed herein.

[0063] The main oscillator 10, MO beam steering unit 20, power oscillator 30, PO beam steering unit 40, second OPS 60, monitoring module 70, and laser processor 80 are housed in housing 2a. The first OPS 50 is housed in housing 2b. For example, housing 2b is located on the rear side of housing 2a.

[0064] The main oscillator 10 includes a narrowband module (LNM) 11, a chamber 14, and an output coupler (OC) 17.

[0065] LNM 11 includes a prism expander 12 for narrowing the spectral linewidth and a grating 13. The prism expander 12 and the grating 13 are configured in a Litertow configuration such that the incident angle and the diffraction angle are consistent.

[0066] The output coupling mirror 17 is a reflector with a reflectivity in the range of 40% to 60%. The output coupling mirror 17 and the LNM 11 are configured to form an optical resonator.

[0067] Cavity 14 is disposed in the optical path of the optical resonator. Cavity 14 includes a pair of discharge electrodes 15a and 15b and two windows 16a and 16b through which the pulsed laser PL passes. Cavity 14 contains excimer laser gas. The excimer laser gas may, for example, contain Ar or Kr gas as a rare gas, contain F2 gas as a halogen gas, or contain Ne gas as a buffer gas.

[0068] The MO beam steering unit 20 includes a high-reflectivity mirror 21a and a high-reflectivity mirror 21b. The high-reflectivity mirrors 21a and 21b are configured to direct the pulsed laser PL output from the master oscillator 10 onto the power oscillator 30. The high-reflectivity mirror in this invention is, for example, a plane mirror on the surface of a substrate formed of synthetic quartz or calcium fluoride (CaF2) with a high-reflectivity film formed thereon. The high-reflectivity film is a dielectric multilayer film, such as a film containing fluorides.

[0069] The power oscillator 30 includes a rear mirror 31, a cavity 32, and an output coupling mirror 35. The rear mirror 31 and the output coupling mirror 35 are configured to form an optical resonator. The power oscillator 30 is an example of an "amplifier" according to the technology disclosed herein.

[0070] Cavity 32 is positioned in the optical path of the optical resonator. Cavity 32 can have the same structure as cavity 14 of the master oscillator 10. That is, cavity 32 includes a pair of discharge electrodes 33a and 33b and two windows 34a and 34b through which the pulsed laser PL passes. Cavity 32 internally houses the excimer laser gas.

[0071] The rear mirror 31 is a reflector with a reflectivity in the range of 50% to 90%. The output coupling mirror 35 is a reflector with a reflectivity in the range of 10% to 30%.

[0072] The PO beam steering unit 40 includes high-reflectivity mirrors 41 to 43 for exchanging light with the first OPS 50. High-reflectivity mirror 41 is configured to reflect the pulsed laser PL output from the power oscillator 30, causing it to be incident on high-reflectivity mirror 42. High-reflectivity mirror 42 is configured to reflect the pulsed laser PL reflected by high-reflectivity mirror 41, causing it to be incident on the first OPS 50. High-reflectivity mirror 43 is configured to reflect the pulsed laser PL output from the first OPS 50, causing it to be incident on the second OPS 60.

[0073] The first OPS 50 includes a beam splitter 51 and a plurality of concave mirrors 52. The beam splitter 51 is disposed in the optical path of the pulsed laser PL after being reflected by the high-reflectivity mirror 42. The beam splitter 51 is a partial reflector that allows a portion of the incident pulsed laser PL to pass through and reflects another portion. The reflectivity of the beam splitter 51 is preferably in the range of 40% to 70%, more preferably about 60%.

[0074] Multiple concave mirrors 52 form a loop optical path that causes a portion of the pulsed laser PL, reflected by the beam splitter 51, to circle back to the beam splitter 51. A portion of the pulsed laser PL incident from the high-reflectivity mirror 42 and transmitted through the beam splitter 51 overlaps with a portion of the pulsed laser PL that has circled at least once on the loop optical path and been reflected by the beam splitter 51. Thus, the pulse width of the pulsed laser PL is extended. In this disclosure, pulse width refers to the time width of the pulse.

[0075] Additionally, high-reflectivity mirrors 53 and 54 are provided inside the housing 2b. These mirrors are configured to reflect the pulsed laser PL, whose pulse width has been extended by the first OPS 50, and then incident it onto the high-reflectivity mirror 43.

[0076] The optical path length of the loop optical path formed by the multiple concave mirrors 52 is preferably in the range of 30m or more and 75m or less. The total number of the multiple concave mirrors 52 is preferably in the range of 16 or more and 34 or less.

[0077] The second OPS 60 includes a beam splitter 61 and a plurality of concave mirrors 62. The beam splitter 61 is disposed in the optical path of the pulsed laser PL after being reflected by the high-reflectivity mirror 43. The beam splitter 61 is a partial reflector that allows a portion of the incident pulsed laser PL to pass through and reflects another portion. The reflectivity of the beam splitter 61 is preferably in the range of 40% to 70%, more preferably about 60%.

[0078] Multiple concave mirrors 62 form a loop optical path that causes a portion of the pulsed laser PL, reflected by the beam splitter 61, to circle around and return to the beam splitter 61. A portion of the pulsed laser PL incident from the high-reflectivity mirror 43 and passing through the beam splitter 61 overlaps with a portion of the pulsed laser PL that has circled at least once on the loop optical path and been reflected by the beam splitter 61. As a result, the pulse width of the pulsed laser PL is extended.

[0079] The optical path length of the loop optical path formed by the multiple concave mirrors 62 is preferably in the range of 5m or more and 25m or less. The total number of the multiple concave mirrors 62 is preferably in the range of 4 or more and 12 or less. Therefore, the optical path length of the first OPS 50 is longer than the optical path length of the second OPS 60.

[0080] The monitoring module 70 includes beam splitters 71 and 72, an energy detector 73, and a spectral detector 74. Beam splitter 71 is configured in the optical path of the pulsed laser PL output from the second OPS 60. Beam splitter 71 is a partial reflector that allows a portion of the incident pulsed laser PL to pass through and reflects another portion.

[0081] Beam splitter 72 is disposed in the optical path of the pulsed laser PL after being reflected by beam splitter 71. Beam splitter 72 is a partial reflector that allows a portion of the incident pulsed laser PL to pass through and reflects another portion.

[0082] An energy detector 73 is positioned in the optical path of the pulsed laser PL after it is reflected by the beam splitter 72 to detect the pulse energy of the pulsed laser PL. A spectral detector 74 is positioned in the optical path of the pulsed laser PL that is transmitted through the beam splitter 72 to detect the spectral linewidth and wavelength of the pulsed laser PL.

[0083] An exposure device 200, serving as an external device, is connected to the laser device 2, allowing pulsed laser PL, which has passed through the beam splitter 71, to be incident upon it. The exposure device 200 is equipped with an exposure control processor 210. The exposure control processor 210 is connected to the laser processor 80.

[0084] The laser processor 80 is connected to the exposure control processor 210, the main oscillator 10, the power oscillator 30, and the monitoring module 70.

[0085] 2.2 Actions

[0086] Next, the operation of the laser device 2 involved in the comparative example will be explained. First, the laser processor 80 receives data including the target pulse energy, target wavelength, and target spectral linewidth from the exposure control processor 210. When the laser processor 80 receives a light emission trigger from the exposure control processor 210, a high-voltage pulse is applied between the discharge electrodes 15a and 15b of the master oscillator 10.

[0087] When a discharge occurs between discharge electrodes 15a and 15b, the laser gas is excited and undergoes laser oscillation through an optical resonator composed of output coupling mirror 17 and LNM 11. Consequently, a narrowband pulsed laser PL is output from output coupling mirror 17. This pulsed laser PL is then incident as a seed light onto the rear mirror 31 of power oscillator 30 via MO beam steering unit 20.

[0088] At the moment the seed light passing through the rear mirror 31 is incident, a high-voltage pulse is applied between the discharge electrodes 33a and 33b by a power source not shown. When discharge occurs between the discharge electrodes 33a and 33b, the laser gas is excited, and the seed light is amplified by a Fabry-Perot type optical resonator composed of the output coupling mirror 35 and the rear mirror 31. The amplified pulsed laser PL is output from the output coupling mirror 35. The pulsed laser PL is ultraviolet light in the ultraviolet wavelength region within the wavelength range of 150 nm to 380 nm.

[0089] The pulsed laser PL output from the output coupling mirror 35 is incident on the PO beam steering unit 40, and its direction of travel is changed so that it is incident on the first OPS 50.

[0090] The pulse width of the pulsed laser PL incident on the first OPS 50 is extended and returned to the PO beam steering unit 40, and its direction of travel is changed so that it is incident on the second OPS 60.

[0091] The pulsed laser PL incident on the second OPS 60 is output after the pulse width is further extended. The pulsed laser PL output from the second OPS 60 is incident on the monitoring module 70, part of which is reflected by the beam splitter 71, and the other part is output from the laser device 2 and incident on the exposure device 200.

[0092] In the monitoring module 70, the pulse energy is detected by the energy detector 73, and the spectral linewidth and wavelength are detected by the spectral detector 74.

[0093] Based on the pulse energy detection results, the laser processor 80 controls the high-voltage pulse applied between the discharge electrodes 33a and 33b so that the pulse energy of the pulsed laser PL output from the laser device 2 becomes the target pulse energy.

[0094] In addition, the laser processor 80 controls the rotating stage of the prism beam expander 12 (not shown) within the LNM 11 based on the wavelength detection result, so that the wavelength of the pulsed laser PL output from the laser device 2 becomes the target wavelength.

[0095] In addition, the laser processor 80 controls a wavefront adjuster (not shown) based on the detection result of the spectral linewidth, so that the spectral linewidth of the pulsed laser PL output from the laser device 2 becomes the target spectral linewidth.

[0096] By extending the pulse width of the pulsed laser PL through the first OPS 50 and the second OPS 60, coherence is reduced. This suppresses speckle formation. Speckle refers to the bright and dark spots that appear due to interference when a laser beam is scattered by a random medium.

[0097] 2.3 Research Topic

[0098] Next, the problem of the laser device 2 involved in the comparative example will be explained. In the laser device 2 involved in the comparative example, a device for extending the optical path length, such as the first OPS 50 and the second OPS 60, is arranged. Therefore, due to the expansion of the pulsed laser PL, vignetting and other phenomena occur within the exposure apparatus 200, resulting in energy loss. Here, vignetting refers to the phenomenon that part of the beam is blocked by the optical system.

[0099] As a method to suppress this energy loss, consider using... Figure 3 The relay lens 110 shown is disposed in the optical path of the pulsed laser PL. The beam divergence angle is reduced by adjusting the distance between the upstream lens 100a and the downstream lens 100b, i.e., the inter-lens distance. For example, the relay lens 110 is disposed in the optical path of the pulsed laser PL between the first OPS 50 and the second OPS 60.

[0100] However, as Figure 2 As shown, the beam divergence angle differs along the long side of the beam cross-section, i.e., the first direction β, from that along the short side, i.e., the second direction γ. That is, the inter-lens distance that minimizes the beam divergence angle in the first direction β differs from the inter-lens distance that minimizes the beam divergence angle in the second direction γ. Therefore, in the laser device 2 described in the comparative example, it is impossible to simultaneously reduce the beam divergence angle in both the long and short sides of the beam cross-section.

[0101] This disclosure provides a discharge-excited laser device capable of simultaneously reducing the beam divergence angle in both the long and short sides of the beam cross-section.

[0102] 3. First Implementation Method

[0103] The laser device 2 according to the first embodiment of this disclosure will be described. Furthermore, structures identical to those described above will be labeled with the same reference numerals, and repeated descriptions will be omitted unless specifically stated otherwise.

[0104] 3.1 Structure

[0105] The laser device 2 described in this embodiment has the same structure as the laser device 2 described in the comparative example, except that a relay lens is added.

[0106] Figure 6 and Figure 7A structural example of the laser device 2 according to the first embodiment is shown in general. Figure 6 This indicates a view of the internal structure of laser device 2 from the front. Figure 7 This indicates the internal structure of the laser device 2 as viewed from above.

[0107] The relay lens involved in this embodiment includes a first lens 91 and a second lens 92. The second lens 92 is disposed downstream of the first lens 91 in the optical path of the pulsed laser PL.

[0108] In this embodiment, the first lens 91 and the second lens 92 are disposed in the optical path of the pulsed laser PL between the first OPS 50 and the second OPS 60. Specifically, the first lens 91 is disposed within the housing 2b, and the second lens 92 is disposed within the housing 2a. For example, the first lens 91 is disposed between the beam splitter 51 and the high-reflectivity mirror 53. The second lens 92 is disposed between the high-reflectivity mirror 43 and the beam splitter 61. That is, the second lens 92 is disposed outside the housing 2b of the first OPS 50 and upstream of the second OPS 60.

[0109] The second lens 92 is held in place by the optical path length changing mechanism 93 so that it can move along the optical path of the pulsed laser PL. The optical path length changing mechanism 93 is connected to the laser processor 80.

[0110] Figure 8 The structure of the first lens 91 is shown. The first lens 91 has a convex spherical surface 91a and a plane 91b that are opposite each other. That is, the first lens 91 is a spherical plano-convex lens. The first lens 91 is arranged such that the plane 91b is perpendicular to the optical axis direction α. ​​At the position where the first lens 91 is arranged, the optical axis direction α corresponds to the H-axis direction, the first direction β corresponds to the V-axis direction, and the second direction γ corresponds to the Z-axis direction.

[0111] The focal length of the first lens 91 is determined by the optical characteristics of the convex spherical surface 91a. The optical power of the convex spherical surface 91a is equal in the first direction β and the second direction γ. Therefore, the focal length of the first lens 91 in the first direction β is equal to the focal length in the second direction γ.

[0112] Figure 9 The structure of the second lens 92 is shown. The second lens 92 has a convex spherical surface 92a and a convex cylindrical surface 92b opposite to each other. The focal length of the convex spherical surface 92a is preferably equal to that of the convex spherical surface 91a. The convex cylindrical surface 92b is a portion of a cylindrical surface whose central axis is parallel to the second direction γ. In the position where the second lens 92 is disposed, the optical axis direction α corresponds to the Z-axis direction, the first direction β corresponds to the V-axis direction, and the second direction γ corresponds to the H-direction.

[0113] The focal length of the second lens 92 is determined by the optical characteristics of the convex spherical surface 92a and the convex cylindrical surface 92b. The convex spherical surface 92a has equal optical power in the first direction β and the second direction γ. The convex cylindrical surface 92b has optical power only in the first direction β, causing the pulsed laser PL to converge in the first direction β. Therefore, as... Figure 10 As shown, the focal length F of the second lens 92 in the first direction β β Focal length F in the second direction γ γ Short. In addition, the focal length of the convex spherical surface 92a is the same as the focal length of the convex spherical surface 91a of the first lens 91, preferably in the range of 500mm or more and 1000mm or less.

[0114] Figure 11 This represents the focal length Fc of the convex cylindrical surface 92b. For example... Figure 12 As shown, the focal length Fc is preferably determined as follows: the beam divergence angle of the pulsed laser PL in the first direction β. β The beam divergence angle θ in the second direction γ γ The difference is minimized.

[0115] Furthermore, when the length of the first direction β of the beam cross section of the pulsed laser PL incident on the second lens 92 is h, the focal length Fc is preferably determined to satisfy the following equation (1).

[0116] 0.3mrad≤h / Fc≤1.5mrad (1)

[0117] Here, h / Fc corresponds to Figure 11 The angle φ is shown. It is assumed that the focal length Fc is sufficiently longer than the length h. mrad is the unit for expressing angles.

[0118] Beam divergence angle θ based on the effect of the convex cylindrical surface 92b β The change in Δθ is represented by the following equation (2).

[0119] (2)

[0120] The first lens 91 and the second lens 92 are arranged opposite each other on the optical path of the pulsed laser PL, with a plane 91b and a convex cylindrical surface 92b facing each other. The pulsed laser PL output from the first OPS 50 is focused on the optical path of the pulsed laser PL between the first lens 91 and the second lens 92. The length of the optical path between the first lens 91 and the second lens 92 is equal to the sum of the focal length of the first lens 91 and the focal length of the convex spherical surface 92a of the second lens 92.

[0121] Figure 13 and Figure 14 This indicates the structure of the optical path length changing mechanism 93. Figure 13 This is a diagram of the optical path length changing mechanism 93 viewed from the optical axis direction α. Figure 14This is a diagram of the optical path length changing mechanism 93 viewed from the second direction γ.

[0122] The optical path length changing mechanism 93 includes a lens holder 93a and a linear stage 93b. The lens holder 93a holds the second lens 92 such that the optical axis A passes through the center of the second lens 92. The linear stage 93b holds the lens holder 93a so that it can move freely along the optical axis direction α. ​​Based on control from the laser processor 80, the linear stage 93b moves the second lens 92 along the optical axis direction α, thereby changing the optical path length between the first lens 91 and the second lens 92.

[0123] 3.2 Actions

[0124] The operation of the laser device 2 in this embodiment is the same as that in the comparative example. In this embodiment, the optical path length changing mechanism 93 can be used for adjustment before the laser device 2 is operated.

[0125] During the adjustment process, firstly, the laser processor 80 controls the optical path length changing mechanism 93 to position the second lens 92 in an initial position. In this initial position, the optical path length between the first lens 91 and the second lens 92 is equal to the sum of the focal length of the first lens 91 and the focal length of the convex spherical surface 92a of the second lens 92.

[0126] When the laser device 2 is operated in this state, the pulsed laser PL incident on the first lens 91 converges behind the first lens 91 and then enters the second lens 92. Through the action of the convex cylindrical surface 92b, the first direction β of the pulsed laser PL incident on the second lens 92 has a beam divergence angle θ. β Things have changed.

[0127] Laser processor 80 controls optical path length changing mechanism 93 to move second lens 92, thereby adjusting the beam divergence angle θ in the first direction β. β To minimize. For example, the beam divergence angle θ in the first direction β is measured using the aforementioned two-dimensional image sensor 101. β As described above, the focal length Fc of the convex cylindrical surface 92b is determined to cause the beam divergence angle θ in the first direction β to be such that... β The beam divergence angle θ with the second direction γ γ The difference becomes smaller, therefore by making the beam divergence angle θ of the first direction β smaller. β To become the minimum, the beam divergence angle θ in the second direction γ γ It also became the smallest.

[0128] 3.3 Effects

[0129] In this embodiment, a relay lens including a first lens 91 and a second lens 92 is provided in the laser device 2. The focal length of the second lens 92 in the long side direction of the beam cross-section is shorter than its focal length in the short side direction, thus simultaneously reducing the beam divergence angle in both the long and short side directions of the beam cross-section. As a result, energy loss caused by vignetting and other issues within the exposure device 200 is suppressed.

[0130] Furthermore, in this embodiment, the beam divergence angle is adjusted by using the first lens 91 and the second lens 92, thereby suppressing the loss of light caused by transmission and enabling high-precision adjustment.

[0131] Alternatively, the second lens 92 can be positioned upstream of the first lens 91, but it is preferable to position the second lens 92 downstream of the first lens 91. This is because adjusting the beam divergence angle downstream is more preferable than upstream.

[0132] 4. Second Implementation Method

[0133] The laser device 2 according to the second embodiment of this disclosure will be described.

[0134] 4.1 Structure

[0135] Regarding the laser device 2 involved in this embodiment, except for the one used in place of the second lens 92... Figure 15 Apart from the second lens 94 shown, it has the same structure as the laser device 2 according to the first embodiment.

[0136] Figure 15 The structure of the second lens 94 according to the second embodiment is shown. The second lens 94 is a toric lens having a toric surface 94a and a plane 94b that are opposite to each other. The first curvature of the toric surface 94a about an axis parallel to the first direction β and the second curvature about an axis parallel to the second direction γ are different, and the second curvature is smaller than the first curvature. That is, the first curvature of the toric surface 94a that converges the pulsed laser PL in the first direction β is greater than the second curvature that converges the pulsed laser PL in the second direction γ. At the position where the second lens 94 is disposed, the optical axis direction α corresponds to the Z-axis direction, the first direction β corresponds to the V-axis direction, and the second direction γ corresponds to the H-direction.

[0137] Figure 16 The focal length F1 based on the first curvature and the focal length F2 based on the second curvature of the second lens 94 are indicated. The focal length F1 is less than the focal length F2. The focal length F2 is the same as the focal length of the convex spherical surface 91a of the first lens 91, preferably in the range of 500 mm or more and 1000 mm or less.

[0138] like Figure 12As shown, the focal length F1 is preferably determined such that the beam divergence angle θ of the pulsed laser PL in the first direction β β The beam divergence angle θ in the second direction γ γ Minimize the difference.

[0139] Furthermore, the focal length F1 can also be determined as follows: when the length of the first direction β of the beam cross section of the pulsed laser PL incident on the second lens 94 is h, it satisfies the following equation (3).

[0140] 0.3mrad≤(h / F1-h / F2)≤1.5mrad (3)

[0141] Similar to the first embodiment, the second lens 94 is held by the optical path length changing mechanism 93 so that it can move along the optical path of the pulsed laser PL.

[0142] 4.2 Actions

[0143] The operation of the laser device 2 in this embodiment is the same as that in the comparative example. In this embodiment, the optical path length changing mechanism 93 can be used for adjustment before the laser device 2 is operated.

[0144] In the adjustment process, firstly, the laser processor 80 controls the optical path length changing mechanism 93 to position the second lens 94 in an initial position, where the optical path length between the first lens 91 and the second lens 94 is equal to the sum of the focal length of the first lens 91 and the focal length F2 of the second lens 94 based on the second curvature.

[0145] When the laser device 2 is operated in this state, the pulsed laser PL incident on the first lens 91 converges behind the first lens 91 and then enters the second lens 94. Due to the action of the first and second curvatures of the complex surface 94a, the beam divergence angle θ of the pulsed laser PL incident on the second lens 94 in the first direction β is... β and the beam divergence angle θ in the second direction γ γ Things have changed.

[0146] Laser processor 80 controls optical path length changing mechanism 93 to move second lens 94, thereby adjusting the beam divergence angle θ in the first direction β. β To become the minimum. As described above, the focal length F1 of the complex surface 94a based on the first curvature is determined to make the beam divergence angle θ of the first direction β the minimum. β The beam divergence angle θ with the second direction γ γ The difference becomes smaller, therefore, by making the beam divergence angle θ of the first direction β smaller... β To become the minimum, the beam divergence angle θ in the second direction γ γ It also became the smallest.

[0147] 4.3 Effects

[0148] In this embodiment, the laser device 2 is provided with a relay lens including a first lens 91 and a second lens 94. The second lens 94 has a complex surface 94a. The first curvature of this complex surface 94a that converges the pulsed laser PL in the long side direction of the beam cross-section is greater than the second curvature that converges the pulsed laser PL in the short side direction. Therefore, the beam divergence angle in both the long and short side directions of the beam cross-section can be reduced simultaneously. As a result, energy loss caused by vignetting and other factors within the exposure device 200 is suppressed.

[0149] In this embodiment, the beam divergence angle is also adjusted by the first lens 91 and the second lens 94, thus suppressing the loss of light caused by transmission and making high-precision adjustments.

[0150] Alternatively, the second lens 94 can be positioned upstream of the first lens 91, but it is preferable to position the second lens 94 downstream of the first lens 91. This is because adjusting the beam divergence angle downstream is more preferable than upstream.

[0151] 5. Variations

[0152] The following describes various variations of the above embodiments.

[0153] In the above embodiments, a power oscillator 30, which serves as an amplifier, is provided between the main oscillator 10 and the first OPS 50 in the laser device 2. However, the power oscillator 30 is not necessary and can be omitted depending on the purpose of the device.

[0154] In addition, in the above embodiments, the relay lens is disposed between the first OPS 50 and the second OPS 60, but it may also be disposed downstream of the second OPS 60.

[0155] Furthermore, in the above embodiments, two optical pulse stretchers, a first OPS 50 and a second OPS 60, are provided in the laser device 2, but it is sufficient to provide at least one optical pulse stretcher. In this case, it is preferable to place the relay lens downstream of the optical pulse stretcher.

[0156] 6. Manufacturing methods for electronic devices

[0157] Figure 17The following is a schematic representation of the structure of the exposure apparatus 200. The exposure apparatus 200 includes an illumination optics system 204 and a projection optics system 206. The illumination optics system 204 illuminates, for example, a mask pattern (not shown) disposed on a mask stage RT using a pulsed laser PL incident from the laser device 2. The projection optics system 206 projects and reduces the pulsed laser PL transmitted through the mask onto a workpiece (not shown) disposed on a workpiece stage WT. The workpiece is a photosensitive substrate such as a semiconductor wafer coated with photoresist.

[0158] The exposure apparatus 200 exposes the workpiece with a pulsed laser PL reflecting the mask pattern by synchronously and parallelly moving the mask stage RT and the workpiece stage WT. After transferring the mask pattern onto a semiconductor wafer through the above exposure process, a semiconductor device can be manufactured through multiple processes. The semiconductor device is an example of the "electronic device" in this disclosure.

[0159] Processors such as laser processor 80 and exposure control processor 210 can also be physically configured in hardware to execute the various processes included in this disclosure. For example, the processor can also be a computer, which includes a memory storing control programs that define various processes and a processing device for executing the control programs. The control programs can be stored in a single memory or separately in multiple physically separate memories, defining various processes through the control programs as a collection of these memories. The processing device can be a general-purpose processing device such as a CPU (Central Processing Unit) or a purpose-specific processing device such as a GPU (Graphics Processing Unit).

[0160] Alternatively, the processor can also be programmed in software to perform the various processes included in this disclosure. For example, the processor's ability to perform various processes can also be implemented in a special-purpose device such as an ASIC (Application Specific Integrated Circuit) or a programmable device such as a FPGA (Field Programmable Gate Array).

[0161] The various processes included in this disclosure can be executed by a single computer, a single dedicated device, or a single programmable device, or by the cooperation of multiple physically separate computers, dedicated devices, or programmable devices. The various processes can also be executed by a combination of at least two of more than one computer, more than one dedicated device, and more than one programmable device.

[0162] The foregoing description is not limiting but merely illustrative. Therefore, it will be apparent to those skilled in the art that modifications can be made to the embodiments of this disclosure without departing from the claims. Furthermore, combinations of embodiments of this disclosure will also be apparent to those skilled in the art. Unless otherwise stated, the terms used throughout this specification and the claims should be interpreted as “non-limiting” terms. For example, terms such as “comprising,” “having,” “possessing,” and “comprise” should be interpreted as “not excluding the presence of constituent elements other than those described.” Furthermore, the modifier “a” should be interpreted as meaning “at least one” or “one or more.” Additionally, 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,” and should be interpreted as including combinations thereof with portions other than “A,” “B,” and “C.”

Claims

1. A laser device, wherein, The laser device includes: A discharge-excited laser oscillator that outputs pulsed laser light in the ultraviolet wavelength region; The first optical pulse stretcher includes a beam splitter and multiple concave mirrors to extend the pulse width of the pulsed laser. as well as A relay lens, comprising a first lens and a second lens disposed in the optical path of the pulsed laser after the pulse width has been extended. The first lens is a spherical plano-convex lens. The second lens has a shorter focal length in the long side direction of the beam cross-section of the pulsed laser than in the short side direction.

2. The laser device according to claim 1, wherein, The second lens has a convex spherical surface and a convex cylindrical surface that are opposite each other. The convex cylindrical surface causes the pulsed laser to converge along its long side.

3. The laser device according to claim 2, wherein, Given that the length of the long side of the beam cross section is h and the focal length of the convex cylindrical surface is Fc, the relationship 0.3mrad≤h / Fc≤1.5mrad is satisfied.

4. The laser device according to claim 2, wherein, The focal length of the convex spherical surface is in the range of 500mm or more and 1000mm or less.

5. The laser device according to claim 2, wherein, The focal length of the second lens in the short side direction is the same as that of the first lens.

6. The laser device according to claim 1, wherein, The second lens is positioned downstream of the first lens in the optical path.

7. The laser device according to claim 1, wherein, The focal length of the first lens is in the range of 500mm or more and 1000mm or less.

8. The laser device according to claim 1, wherein, The laser device includes: An optical path length changing mechanism that changes the optical path length between the first lens and the second lens; and The processor controls the optical path length changing mechanism.

9. The laser device according to claim 8, wherein, The processor alters the optical path length in a manner that reduces the beam divergence angle of the pulsed laser along its long side.

10. The laser device according to claim 8, wherein, The second lens is positioned downstream of the first lens in the optical path. The optical path length changing mechanism changes the optical path length by moving the second lens.

11. The laser device according to claim 1, wherein, An amplifier for amplifying the pulsed laser is provided between the laser oscillator and the first optical pulse stretcher.

12. The laser device according to claim 1, wherein, The second lens is a toric lens with a toric surface.

13. The laser device according to claim 12, wherein, The complex surface has a first curvature that converges the pulsed laser in the long side direction and a second curvature that converges the pulsed laser in the short side direction. The second curvature is smaller than the first curvature.

14. The laser device according to claim 13, wherein, Let the length of the long side of the beam cross-section be h, the focal length based on the first curvature be F1, and the focal length based on the second curvature be F2. The relationship is satisfied: 0.3 mrad ≤ (h / F1 - h / F2) ≤ 1.5 mrad.

15. The laser device according to claim 13, wherein, The focal length based on the second curvature is in the range of 500mm or more and 1000mm or less.

16. The laser device according to claim 1, wherein, The laser device includes a second optical pulse stretcher, which is positioned downstream of the first optical pulse stretcher in the optical path. The optical path length of the first optical pulse stretcher is longer than that of the second optical pulse stretcher.

17. The laser device according to claim 16, wherein, The first lens and the second lens are disposed in the optical path between the first optical pulse stretcher and the second optical pulse stretcher.

18. The laser device according to claim 16, wherein, The first lens is disposed within a housing that houses the first optical pulse stretcher. The second lens is disposed outside the housing and positioned upstream of the optical path than the second optical pulse stretcher.

19. The laser device according to claim 16, wherein, The first lens and the second lens are positioned downstream of the optical path from the second optical pulse stretcher.

20. A method for manufacturing an electronic device, wherein, include: Pulsed laser light is output from the laser device to the exposure device. In order to manufacture electronic devices, the photosensitive substrate is exposed using the pulsed laser within the exposure apparatus. The laser device includes: A discharge-excited laser oscillator that outputs pulsed laser light in the ultraviolet wavelength region; The first optical pulse stretcher includes a beam splitter and multiple concave mirrors to extend the pulse width of the pulsed laser. as well as A relay lens, comprising a first lens and a second lens disposed in the optical path of the pulsed laser after the pulse width has been extended. The first lens is a spherical plano-convex lens. The second lens has a shorter focal length in the long side direction of the beam cross-section of the pulsed laser than in the short side direction.

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