Laser system and method for manufacturing electronic device

Abstract

A laser system according to one aspect of the present disclosure includes: a first container housing a first crystal holder and a first heater for holding a first nonlinear crystal, and including a first entrance window for laser light to enter and a first exit window for laser light to exit after passing through the first nonlinear crystal; a second container housing a second crystal holder and a second heater for holding a second nonlinear crystal, and including a second entrance window for laser light to enter and a second exit window for laser light to exit after passing through the second nonlinear crystal; and a stage for holding the first and second containers. A controller controls the stage to remove the first nonlinear crystal from the laser light path and insert the second nonlinear crystal into the laser light path.

Description

Technical Field

[0001] The present disclosure relates to methods of manufacturing laser systems and electronic devices. Background Art

[0002] With the miniaturization and high integration of semiconductor integrated circuits, semiconductor exposure equipment is required to achieve higher resolution. Hereinafter, semiconductor exposure equipment will be referred to simply as "exposure equipment." Consequently, there has been a trend toward shorter wavelengths of light emitted from exposure light sources. Gas lasers are being used in place of conventional mercury lamps. Currently, gas lasers used for exposure include KrF excimer lasers, which emit ultraviolet light at a wavelength of 248 nm, and ArF excimer lasers, which emit ultraviolet light at a wavelength of 193 nm.

[0003] As a currently used exposure technology, liquid immersion exposure is a practical method that uses liquid to fill the gap between the projection lens and the wafer on the exposure device side. By changing the refractive index of this gap, the apparent wavelength of the exposure light source is shortened. When using an ArF excimer laser as the exposure light source, the wafer is irradiated with ultraviolet light of an equivalent wavelength of 134 nm. This technique is called ArF immersion exposure and is also known as ArF immersion lithography.

[0004] The spectral line width in the natural oscillation of KrF and ArF excimer laser devices is relatively wide, approximately 350 to 400 pm. Therefore, the laser light (ultraviolet light) projected onto the wafer through the projection lens on the exposure device side produces chromatic aberration, which reduces the resolution. 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. The spectral line width is also called the spectrum width. Therefore, a narrowing section (Line Narrow Module) having a narrowing element is provided in the laser resonator of the gas laser device, and the narrowing of the spectrum width is achieved by this narrowing section. In addition, the narrowing element can also be an etalon or a grating. Such a laser device with a narrowed spectral width is called a narrowed laser device.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent No. 6418752 Summary of the Invention

[0008] A laser system according to one aspect of the present disclosure comprises: a solid-state laser device that outputs laser light; a first crystal holder that holds a first nonlinear crystal arranged on an optical path of the laser light; a first heater that heats the first nonlinear crystal; a first container that houses the first heater and the first crystal holder and includes a first incident window for laser light incidence and a first exit window for laser light exit; a first gas inlet pipe that introduces a first gas into the first container; a first gas outlet pipe that exhausts the first gas in the first container; a second crystal holder that holds the second nonlinear crystal arranged outside the optical path of the laser light; a linear crystal; a second heater for heating the second nonlinear crystal; a second container for accommodating the second heater and the second crystal holder, comprising a second incident window for laser incidence and a second exit window for laser emission when the container is arranged on an optical path of the laser; a second gas inlet pipe for introducing the first gas into the second container; a second gas exhaust pipe for exhausting the first gas from the second container; a carrier for holding the first container and the second container; and a controller for controlling the carrier to remove the first nonlinear crystal from the optical path of the laser and insert the second nonlinear crystal into the optical path of the laser.

[0009] According to one aspect of the present disclosure, a method for manufacturing an electronic device comprises the following steps: generating an excimer laser by a laser system, outputting the excimer laser to an exposure device, and exposing the excimer laser to a photosensitive substrate in the exposure device to manufacture the electronic device, wherein the laser system comprises: a solid-state laser device that outputs laser light; a first crystal holder that holds a first nonlinear crystal arranged on an optical path of the laser light; a first heater that heats the first nonlinear crystal; a first container that accommodates the first heater and the first crystal holder and comprises a first incident window for laser light incidence and a first exit window for laser light exit; a first gas inlet pipe that introduces a first gas into the first container; a first gas exhaust pipe that exhausts the first gas in the first container; a second crystal holder; and a second gas outlet pipe. A holder that holds a second nonlinear crystal arranged outside the optical path of the laser; a second heater that heats the second nonlinear crystal; a second container that accommodates the second heater and the second crystal holder and includes a second incident window for laser incidence and a second exit window for laser emission when the second container is arranged on the optical path of the laser; a second gas inlet pipe that introduces the first gas into the second container; a second gas exhaust pipe that exhausts the first gas in the second container; a stage that holds the first and second containers; a controller that controls the stage to detach the first nonlinear crystal from the optical path of the laser and insert the second nonlinear crystal into the optical path of the laser; and an excimer amplifier that amplifies the laser emitted from the first exit window or the second exit window. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Hereinafter, several embodiments of the present disclosure will be described as simple examples with reference to the accompanying drawings.

[0011] Figure 1 This is a diagram schematically showing a configuration example of a laser system.

[0012] Figure 2 This is a structural diagram showing an example of a wavelength conversion system.

[0013] Figure 3 This is a diagram schematically showing the configuration of a solid-state laser system according to the first embodiment.

[0014] Figure 4 It is shown from Figure 3 The state shown is a diagram showing a state after the movable part has moved.

[0015] Figure 5 This is a flowchart showing an example of a control method for a solid-state laser system.

[0016] Figure 6 This is a diagram showing the incident surface of the laser beam of the second CLBO crystal.

[0017] Figure 7 This is a diagram schematically showing the configuration of a solid-state laser system according to a second embodiment.

[0018] Figure 8 It is shown from Figure 7 The state shown is a diagram showing a state after the movable part has moved.

[0019] Figure 9 It is a diagram schematically showing a configuration example of an exposure apparatus. DETAILED DESCRIPTION

[0020] -Table of contents-

[0021] 1. Explanation of terms

[0022] 2. Laser System Overview

[0023] 2.1 Structure

[0024] 2.1.1 Structure of the laser system

[0025] 2.1.2 Structure of the wavelength conversion system

[0026] 2.2 Action

[0027] 3.Topic

[0028] 4. Implementation Method 1

[0029] 4.1 Structure

[0030] 4.2 Action

[0031] 4.2.1 Control of crystal replacement

[0032] 4.2.2 Determining the Timing of Starting Preparations for the Preparatory Unit

[0033] 4.3 Action / Effect

[0034] 5. Implementation Method 2

[0035] 5.1 Structure

[0036] 5.2 Action

[0037] 5.3 Action / Effect

[0038] 6. Method for manufacturing electronic devices

[0039] 7. Others

[0040] Below, embodiments of the present disclosure are described in detail with reference to the accompanying drawings. The embodiments described below illustrate several examples of the present disclosure and do not limit the content of the present disclosure. In addition, the structures and actions described in each embodiment are not necessarily all required structures and actions of the present disclosure. In addition, the same reference numerals are given to the same structural elements, and repeated descriptions are omitted.

[0041] 1. Explanation of terms

[0042] The terms used in this specification are defined as follows.

[0043] A "hybrid laser device" refers to a two-stage laser device consisting of an oscillation stage (master oscillator) and an amplifier stage (amplifier), in which the oscillation stage includes a solid-state laser device and the amplifier stage includes an excimer laser device. An "excimer amplifier" refers to an excimer laser device used in the amplifier stage.

[0044] The terms “perpendicular” or “orthogonal” in this specification may include concepts of approximately perpendicular or approximately orthogonal, which can be regarded as the same as substantially perpendicular or substantially orthogonal in a technical sense.

[0045] 2. Laser System Overview

[0046] 2.1 Structure

[0047] 2.1.1 Structure of the laser system

[0048] Figure 1 1 is a diagram schematically showing a configuration example of a solid-state laser system 1. The solid-state laser system 1 includes a first solid-state laser device 10 that outputs a first pulsed laser, a second solid-state laser device 12 that outputs a second pulsed laser, a wavelength conversion system 14, a synchronization circuit unit 20, and a control unit 22.

[0049] Here, the traveling direction of the laser beam is defined as the “Z direction.” A direction perpendicular to the Z direction is defined as the “V direction,” and a direction perpendicular to the V direction and the Z direction is defined as the “H direction.”

[0050] The first solid-state laser device 10 includes a first semiconductor laser 24 , a first semiconductor optical amplifier SOA 26 , a Yb fiber amplifier system 28 , a Yb:YAG (Yttrium Aluminum Garnet) crystal amplifier 30 , and an LBO (LiB 3 O 5 ) crystal 32 .

[0051] The first semiconductor laser 24 ( Figure 1 The semiconductor laser 1) in the figure is a single longitudinal mode laser that emits seed light with a wavelength of approximately 1030 nm by CW oscillation or pulse oscillation. The first semiconductor laser 24 may be, for example, a distributed feedback (DFB) semiconductor laser.

[0052] The first semiconductor optical amplifier SOA26 (in Figure 1 The semiconductor optical amplifier SOA1 in the figure is a semiconductor element that converts CW or pulsed seed light into pulsed laser light of a predetermined pulse width by passing a pulse current through the semiconductor in a current controller (not shown).

[0053] The Yb fiber amplifier system 28 includes a multi-stage fiber amplifier 28A doped with Yb, and a CW pumping semiconductor laser (not shown) that emits pumping light by CW oscillation and supplies the pumping light to each fiber amplifier 28A.

[0054] The Yb:YAG crystal amplifier 30 is a YAG crystal doped with Yb. In addition, the LBO crystal 32 is a nonlinear crystal.

[0055] On the other hand, the second solid-state laser device 12 includes a second semiconductor laser 36 ( Figure 1 Semiconductor laser 2), second semiconductor optical amplifier SOA38 (in Figure 1 In the figure, it is indicated as a semiconductor optical amplifier SOA2) and an Er fiber amplifier system 40.

[0056] The second semiconductor laser 36 is a single longitudinal mode laser that emits seed light having a wavelength of approximately 1553 nm by CW oscillation or pulse oscillation. The second semiconductor laser 36 may be, for example, a distributed feedback (DFB) semiconductor laser.

[0057] The second semiconductor optical amplifier SOA38 is a semiconductor element that converts CW or pulsed seed light into pulsed laser light having a predetermined pulse width by allowing a pulse current to flow through the semiconductor through a current controller (not shown).

[0058] The Er fiber amplifier system 40 includes a multi-stage fiber amplifier 40A each doped with Er and Yb, and a CW pumping semiconductor laser (not shown) that emits pumping light by CW oscillation and supplies the pumping light to each fiber amplifier 40A.

[0059] The wavelength conversion system 14 includes a wavelength conversion box 42 as a housing, a first window 44, a second window 46, and a third window 48. In addition, the wavelength conversion system 14 includes a first CLBO (CsLiB6O) inside the wavelength conversion box 42. 10 ) crystal 50, the second CLBO crystal 52, the third CLBO crystal 54, the first high reflective mirror 56, the second high reflective mirror 58, the first dichroic mirror 60, the second dichroic mirror 62, the third dichroic mirror 64, the first HVθ stage 66 and the second HVθ stage 68.

[0060] The wavelength conversion box 42 is an example of the "third container" of the present disclosure. The first window 44 and the second window 46 are arranged on the incident side of the wavelength conversion box 42. In addition, the third window 48 is arranged on the emission side of the wavelength conversion box 42.

[0061] The first window 44 , the first CLBO crystal 50 , the first dichroic mirror 60 , the second CLBO crystal 52 , the second dichroic mirror 62 , the third CLBO crystal 54 , and the third dichroic mirror 64 are arranged in this order on the optical path of the pulsed laser light.

[0062] The first high-reflection mirror 56 is arranged to highly reflect the second pulsed laser light output from the second solid-state laser device 12 and incident from the second window 46 , and to allow the second pulsed laser light to enter the first dichroic mirror 60 .

[0063] The first CLBO crystal 50 (in Figure 1 The nonlinear crystal CLBO 1 in the figure generates a first pulsed laser beam having a wavelength of approximately 258 nm from a pulsed laser beam having a wavelength of approximately 515 nm output from the first solid-state laser device 10 and incident from the first window 44. The first CLBO crystal 50 is an example of the "first nonlinear crystal" disclosed herein.

[0064] The first dichroic mirror 60 is coated with a film that highly transmits the first pulsed laser beam having a wavelength of approximately 258 nm and highly reflects the second pulsed laser beam having a wavelength of approximately 1553 nm. The first dichroic mirror 60 is positioned so that the first and second pulsed laser beams enter the second CLBO crystal 52 with their optical path axes aligned.

[0065] The second CLBO crystal 52 (in Figure 1 The nonlinear crystal (denoted as CLBO2 in the table) uses the incident first pulse laser and second pulse laser to generate a sum-frequency pulse laser with a wavelength of approximately 221 nm.

[0066] The second dichroic mirror 62 is coated with a film that highly reflects the first pulsed laser light having a wavelength of approximately 258 nm and highly transmits the second pulsed laser light having a wavelength of approximately 1553 nm and the pulsed laser light having a wavelength of approximately 221 nm generated by the second CLBO crystal 52 .

[0067] The third CLBO crystal 54 (in Figure 1 The nonlinear crystal (denoted as CLBO3 in the table) is a nonlinear crystal that generates a sum-frequency pulsed laser with a wavelength of approximately 193 nm based on the incident second pulsed laser with a wavelength of approximately 1553 nm and the pulsed laser with a wavelength of approximately 221 nm.

[0068] The third dichroic mirror 64 is coated with a film that highly transmits the second pulsed laser light having a wavelength of approximately 1553 nm and the pulsed laser light having a wavelength of approximately 221 nm, and highly reflects the pulsed laser light having a wavelength of approximately 193 nm.

[0069] The second high-reflection mirror 58 is arranged so as to allow the pulsed laser light having a wavelength of approximately 193 nm to be output from the wavelength conversion system 14 through the third window 48 .

[0070] The second CLBO crystal 52 and the third CLBO crystal 54 are respectively placed on the first HVθ stage 66 and the second HVθ stage 68 via the first crystal holder 90. The first HVθ stage 66 and the second HVθ stage 68 move in the H-axis direction and the V-axis direction, respectively, and rotate around the H-axis.

[0071] The synchronization circuit unit 20 is connected to a signal line so as to be able to control the first semiconductor optical amplifier SOA 26 and the second semiconductor optical amplifier SOA 38 separately.

[0072] The control unit 22 includes a CPU (Central Processing Unit), ROM (Read Only Memory), RAM (Random Access Memory), and input / output interfaces (not shown). Signal lines are connected to the control unit 22 so that it can control the synchronization circuit unit 20, the first HVθ stage 66, and the second HVθ stage 68. Furthermore, the control unit 22 is connected to an external device control unit 98 located outside the solid-state laser system 1 so that communication is possible. The control unit 22 is an example of a "controller" in the present disclosure.

[0073] 2.1.2 Structure of the wavelength conversion system

[0074] Figure 2 1 is a structural diagram showing an example of the wavelength conversion system 14. Figure 2 In the figure, the right direction is defined as the X direction, the upward direction in the figure, which is perpendicular to the X direction, is defined as the Y direction, and the direction perpendicular to the X and Y directions is defined as the Z direction. The wavelength conversion box 42 of the wavelength conversion system 14 includes, in addition to the first window 44, the second window 46, and the third window 48, a first purge gas inlet pipe 70 and a first purge gas outlet pipe 72.

[0075] The first purge gas inlet pipe 70 and the first purge gas outlet pipe 72 respectively connect the interior and exterior of the wavelength conversion box 42. The first purge gas inlet pipe 70 is connected to, for example, a bottle (not shown) that supplies N₂ gas as a purge gas. The first purge gas inlet pipe 70 is an example of the "third gas inlet pipe" of the present disclosure. The first purge gas outlet pipe 72 is an example of the "third gas exhaust pipe" of the present disclosure. Furthermore, N₂ gas is an example of the "second gas" of the present disclosure.

[0076] Furthermore, the wavelength conversion box 42 includes, in addition to the first high reflective mirror 56 and the first dichroic mirror 60, a first CLBO crystal unit 74, a second CLBO crystal unit 76, and a third CLBO crystal unit 78. Figure 2 In the figure, the second high reflection mirror 58, the second dichroic mirror 62, the third dichroic mirror 64, the first HVθ stage 66, and the second HVθ stage 68 are omitted.

[0077] The first CLBO crystal unit 74 , the second CLBO crystal unit 76 , and the third CLBO crystal unit 78 include the first CLBO crystal 50 , the second CLBO crystal 52 , and the third CLBO crystal 54 , respectively.

[0078] The first CLBO crystal unit 74 includes a first container 80 , a second purge gas inlet pipe 86 , a second purge gas outlet pipe 88 , a first crystal holder 90 , and a first heater 92 .

[0079] The second purge gas inlet pipe 86 connects the outside of the wavelength conversion box 42 and the inside of the first container 80. The second purge gas inlet pipe 86 is connected to a bottle (not shown) that supplies Ar gas or He gas as an inert gas to the first CLBO crystal 50. Figure 2 In the example shown, the second purge gas inlet pipe 86 is connected to a bottle of Ar gas as a purge gas. The second purge gas inlet pipe 86 is an example of the "first gas introduction pipe" of the present disclosure. In addition, Ar gas is an example of the "first gas" of the present disclosure.

[0080] The second purge gas outlet pipe 88 communicates the interior of the first container 80 and the interior of the wavelength conversion box 42. The second purge gas outlet pipe 88 is an example of a "first gas exhaust pipe" in the present disclosure.

[0081] The first container 80 includes a first incident window 82 and a first exit window 84. The first container 80 has the first incident window 82 disposed on the incident side of the wavelength conversion box 42 and the first exit window 84 disposed on the exit side.

[0082] Furthermore, the first container 80 accommodates a first crystal holder 90 and a first heater 92. The first crystal holder 90 is a holding member that holds the first CLBO crystal 50. The first heater 92 is a heating member that heats the first CLBO crystal 50.

[0083] In addition, the first CLBO crystal unit 74 , the second CLBO crystal unit 76 , and the third CLBO crystal unit 78 have the same structure, and therefore, the description of the structure of the second CLBO crystal unit 76 and the third CLBO crystal unit 78 is omitted.

[0084] Furthermore, the wavelength conversion system 14 includes a temperature regulator 94 disposed outside the wavelength conversion box 42. The temperature regulator 94 is provided in the control unit 22 (see Figure 1 The temperature regulator 94 is connected to each of the first heaters 92 of the first CLBO crystal unit 74 , the second CLBO crystal unit 76 , and the third CLBO crystal unit 78 .

[0085] 2.2 Action

[0086] The operation of the solid-state laser system 1 will be described. Here, the temperature controller 94 controls the first heaters 92 of the first, second, and third CLBO crystal units 74, 76, and 78, preheating the first, second, and third CLBO crystals 50, 52, and 54 to 150°C. Furthermore, Ar gas is pre-purged from the first, second, and third CLBO crystal units 74, 76, and 78 through the second purge gas inlet and outlet pipes 86 and 88, respectively.

[0087] Furthermore, the interior of the wavelength conversion box 42 is purged in advance with N 2 gas through the first purge gas inlet pipe 70 and the first purge gas outlet pipe 72 .

[0088] The control unit 22 expands various programs such as a control program stored in a ROM (not shown) into a RAM (not shown), and executes the programs expanded into the RAM using a CPU (not shown).

[0089] When the control unit 22 receives the laser oscillation preparation signal and the target oscillation wavelength from the external device control unit 98, it causes the first semiconductor laser 24, the unillustrated CW excitation semiconductor laser provided in the Yb fiber amplifier system 28, the second semiconductor laser 36, and the unillustrated CW excitation semiconductor laser provided in the Er fiber amplifier system 40 to perform CW or pulse oscillation.

[0090] Furthermore, upon receiving a light emission trigger from the external device control unit 98 , the control unit 22 transmits a trigger signal Tr1 to the synchronization circuit unit 20 .

[0091] The synchronization circuit unit 20 , which has received the trigger signal Tr1 from the control unit 22 , transmits control signals to each of the first semiconductor optical amplifier SOA 26 and the second semiconductor optical amplifier SOA 38 .

[0092] The first solid-state laser device 10 converts and amplifies laser light having a wavelength of approximately 1030 nm output from the first semiconductor laser 24 into a predetermined pulse width via the first semiconductor optical amplifier SOA 26 , and injects the pulsed seed light into the Yb fiber amplifier system 28 .

[0093] The pulsed seed light is amplified by the Yb fiber amplifier system 28 and the Yb:YAG crystal amplifier 30. The LBO crystal 32 generates a pulsed laser light having a wavelength of approximately 515 nm based on the amplified pulsed laser light.

[0094] The pulsed laser light having a wavelength of approximately 515 nm output from the first solid-state laser device 10 enters the first CLBO crystal 50 through the first window 44 of the wavelength conversion system 14 .

[0095] The first CLBO crystal 50 generates a first pulsed laser beam having a wavelength of approximately 258 nm using the incident pulsed laser beam having a wavelength of approximately 515 nm, and makes the first pulsed laser beam incident on the first dichroic mirror 60 .

[0096] On the other hand, the second solid-state laser device 12 converts and amplifies the CW or pulsed laser light having a wavelength of approximately 1553 nm output from the second semiconductor laser 36 into a predetermined pulse width via the second semiconductor optical amplifier SOA 38, and then injects the pulsed laser light into the Er fiber amplifier system 40. The Er fiber amplifier system 40 further amplifies the pulsed seed light.

[0097] The second pulsed laser beam having a wavelength of approximately 1553 nm outputted from the second solid-state laser device 12 enters the first high-reflection mirror 56 through the second window 46 of the wavelength conversion system 14 . The first high-reflection mirror 56 highly reflects the incident second pulsed laser beam and enters the first dichroic mirror 60 .

[0098] In response to trigger signal Tr1, the synchronization circuit unit 20 transmits a signal of a predetermined pulse width to the first semiconductor optical amplifier SOA 26 and the second semiconductor optical amplifier SOA 38 at predetermined timings. This predetermined pulse width is adjusted in the wavelength conversion system 14 so that the pulsed laser light having a wavelength of approximately 193 nm has a desired pulse width. By adjusting this pulse width, the pulse width of the pulsed laser light having a wavelength of approximately 193 nm can be adjusted. Furthermore, the predetermined timing is adjusted so that the first pulsed laser light output from the first CLBO crystal 50 and the second pulsed laser light output from the Er fiber amplifier system 40 are incident on the second CLBO crystal 52 at approximately the same time.

[0099] As a result, the first pulsed laser beam with a wavelength of approximately 258 nm and the second pulsed laser beam with a wavelength of approximately 1553 nm are incident on the second CLBO crystal 52 at approximately the same time, and the beams overlap on the second CLBO crystal 52. As a result, the second CLBO crystal 52 generates pulsed laser beams having a sum frequency of approximately 258 nm and approximately 1553 nm, that is, a wavelength of approximately 221 nm.

[0100] The second dichroic mirror 62 highly reflects the pulsed laser light having a wavelength of approximately 258 nm. Furthermore, the second dichroic mirror 62 highly transmits the pulsed laser light having a wavelength of approximately 1553 nm and the pulsed laser light having a wavelength of approximately 221 nm, allowing them to enter the third CLBO crystal 54 .

[0101] The third CLBO crystal 54 generates a pulsed laser beam having a wavelength of approximately 193 nm, which is a sum frequency of approximately 1553 nm and approximately 221 nm, using the incident pulsed laser beam having a wavelength of approximately 1553 nm and a wavelength of approximately 221 nm.

[0102] The third dichroic mirror 64 highly transmits pulsed laser light having a wavelength of approximately 1553 nm and pulsed laser light having a wavelength of approximately 221 nm. Furthermore, the third dichroic mirror 64 highly reflects pulsed laser light having a wavelength of approximately 193 nm, allowing it to enter the second high-reflection mirror 58. The second high-reflection mirror 58 highly reflects the incident pulsed laser light having a wavelength of approximately 193 nm, allowing it to be output from the wavelength conversion system 14 via the third window 48.

[0103] Here, the second CLBO crystal 52 and the third CLBO crystal 54 may be damaged by pulsed laser light of ultraviolet light having a wavelength of approximately 258 nm, a wavelength of approximately 221 nm, and a wavelength of approximately 193 nm.

[0104] Therefore, the control unit 22 controls the first HVθ stage 66 and the second HVθ stage 68 to move the second CLBO crystal 52 and the third CLBO crystal 54 a predetermined distance in the V direction or the H direction for each predetermined number of pulsed laser shots. As a result, the incident point of the laser light can be changed, and the crystal life of the second CLBO crystal 52 and the third CLBO crystal 54 can be extended.

[0105] In addition, when the target wavelength of the output laser is changed by the external device control unit 98, the control unit 22 changes the oscillation wavelength of the first semiconductor laser 24 or the second semiconductor laser 36, and controls the first HVθ stage 66 and the second HVθ stage 68 so that the incident angle with respect to the second CLBO crystal 52 and the incident angle with respect to the third CLBO crystal 54 become phase matching angles corresponding to the target wavelength.

[0106] 3.Topic

[0107] CLBO crystals are deliquescent and hygroscopic, so the interiors of the first, second, and third CLBO crystal units 74, 76, and 78 are purged using a purge gas such as Ar, and the first, second, and third CLBO crystals 50, 52, and 54 are heated to 150°C for use.

[0108] For example, when the life of the first CLBO crystal 50 expires, after the temperature gradually decreases, the wavelength conversion box 42 and the first CLBO crystal unit 74 are opened, and then the first CLBO crystal 50 is replaced.

[0109] Furthermore, the first CLBO crystal 50 is heated inside the first CLBO crystal unit 74 and used while maintaining the temperature. Therefore, after replacement, the heating, temperature increase, and dehydration time of the first CLBO crystal 50 also takes 3 to 4 days, and the overall maintenance takes time.

[0110] Thus, the operation of replacing the CLBO crystal to generate deep ultraviolet light having a wavelength of approximately 193 nm takes time.

[0111] 4. Implementation Method 1

[0112] 4.1 Structure

[0113] Figure 3 1 is a diagram schematically showing the structure of a solid-state laser system 1A according to Embodiment 1. Figure 3 In, with Figure 2 Similarly, the right direction in the figure is defined as the X direction, the upward direction in the figure perpendicular to the X direction is defined as the Y direction, and the direction perpendicular to the X and Y directions is defined as the Z direction. Figure 1 and Figure 2 The differences of the solid-state laser system 1 shown will be described.

[0114] Figure 3 The solid-state laser system 1A shown includes a fourth CLBO crystal unit 100 , a fifth CLBO crystal unit 102 , and a sixth CLBO crystal unit 104 .

[0115] Furthermore, the solid-state laser system 1A includes a first stage 106 , a second stage 108 , and a third stage 110 .

[0116] Furthermore, the solid-state laser system 1A includes a stage controller 112 in the control unit 22 .

[0117] The fourth CLBO crystal unit 100, the fifth CLBO crystal unit 102, and the sixth CLBO crystal unit 104 include a fourth CLBO crystal 120, a fifth CLBO crystal 122, and a sixth CLBO crystal 124, respectively. The fourth CLBO crystal 120 generates the same wavelength as the first CLBO crystal 50. The fourth CLBO crystal 120 is an example of the "second nonlinear crystal" disclosed herein. The fifth CLBO crystal 122 generates the same wavelength as the second CLBO crystal 52. The sixth CLBO crystal 124 generates the same wavelength as the third CLBO crystal 54.

[0118] The fourth CLBO crystal unit 100 includes a second container 130, a second incident window 132, a second exit window 134, a third purge gas inlet pipe 136, a third purge gas outlet pipe 138, a second crystal holder 140, and a second heater 142. The structures of the second container 130, the second incident window 132, the second exit window 134, the third purge gas inlet pipe 136, the third purge gas outlet pipe 138, the second crystal holder 140, and the second heater 142 are respectively similar to the structures of the first container 80, the first incident window 82, the first exit window 84, the second purge gas inlet pipe 86, the second purge gas outlet pipe 88, the first crystal holder 90, and the first heater 92. The third purge gas inlet pipe 136 is an example of the "second gas introduction pipe" in the present disclosure. In addition, the third purge gas outlet pipe 138 is an example of the “second gas exhaust pipe” in the present disclosure.

[0119] The fourth, fifth, and sixth CLBO crystal units 100, 102, and 104 all share a common structure. The second crystal holders 140 of the fourth, fifth, and sixth CLBO crystal units 100, 102, and 104 hold the fourth, fifth, and sixth CLBO crystals 120, 122, and 124, respectively.

[0120] The second purge gas inlet pipes 86 of the first CLBO crystal unit 74 , the second CLBO crystal unit 76 , and the third CLBO crystal unit 78 are connected to a common pipe 96 outside the wavelength conversion box 42 via valves 87A, 87B, and 87C, respectively.

[0121] Similarly, the third purge gas inlet pipes 136 of the fourth CLBO crystal unit 100 , the fifth CLBO crystal unit 102 , and the sixth CLBO crystal unit 104 are connected to the common pipe 96 outside the wavelength conversion box 42 via valves 87D, 87E, and 87F, respectively.

[0122] Valves 87A, 87B, and 87C are controlled by the controller 22 to switch between connecting and blocking the second purge gas inlet pipe 86. Valves 87A, 87B, and 87C may be configured to connect the second purge gas inlet pipe 86 to either the common pipe 96 or a pipe (not shown). The pipe (not shown) may also be connected to a compressor for supplying atmospheric air.

[0123] Similarly, valves 87D, 87E, and 87F are controlled by the controller 22 to switch between connecting and blocking the third purge gas inlet pipe 136. Valves 87D, 87E, and 87F may be configured to connect the third purge gas inlet pipe 136 to either the common pipe 96 or a pipe (not shown). The pipe (not shown) may also be connected to a compressor for supplying atmospheric air.

[0124] At least a portion of each of the second purge gas inlet pipe 86 and the third purge gas inlet pipes 136 is flexible.

[0125] The second heaters 142 of each of the fourth CLBO crystal unit 100 , the fifth CLBO crystal unit 102 , and the sixth CLBO crystal unit 104 are connected to the temperature regulator 94 .

[0126] The first stage 106 includes a rail 150 extending in the Y direction and a movable portion 152 held on the rail 150 so as to be movable in the Y direction along the rail 150. The first CLBO crystal unit 74 and the fourth CLBO crystal unit 100 are held side by side in the Y direction on the movable portion 152.

[0127] The second stage 108 includes a rail 154 extending in the Y direction and a movable portion 156 held on the rail 154 so as to be movable in the Y direction along the rail 154. The second CLBO crystal unit 76 and the fifth CLBO crystal unit 102 are held side by side in the Y direction on the movable portion 156.

[0128] Similarly, the third stage 110 includes a rail 158 extending in the Y direction and a movable portion 160 held on the rail 158 so as to be movable in the Y direction along the rail 158. The third CLBO crystal unit 78 and the sixth CLBO crystal unit 104 are held on the movable portion 160 side by side in the Y direction.

[0129] The first stage 106 , the second stage 108 , and the third stage 110 each include an actuator (not shown). The actuator (not shown) is connected to a stage controller 112 .

[0130] exist Figure 3 In the example shown, the first CLBO crystal 50 , the second CLBO crystal 52 , and the third CLBO crystal 54 are arranged on the optical path of the laser light, and the fourth CLBO crystal 120 , the fifth CLBO crystal 122 , and the sixth CLBO crystal 124 are arranged outside the optical path of the laser light.

[0131] Figure 4 It is shown from Figure 3 The state shown is a diagram showing the state after the movable part 152, the movable part 156, and the movable part 160 have moved. Figure 4 In the example shown, the first CLBO crystal 50 , the second CLBO crystal 52 , and the third CLBO crystal 54 are arranged outside the optical path of the laser light, and the fourth CLBO crystal 120 , the fifth CLBO crystal 122 , and the sixth CLBO crystal 124 are arranged on the optical path of the laser light.

[0132] 4.2 Action

[0133] The operator has previously caused the first crystal holders 90 of the first CLBO crystal unit 74, the second CLBO crystal unit 76, and the third CLBO crystal unit 78 to hold the first CLBO crystal 50, the second CLBO crystal 52, and the third CLBO crystal 54, respectively, and to store them in first containers 80. Similarly, the operator has caused the second crystal holders 140 of the fourth CLBO crystal unit 100, the fifth CLBO crystal unit 102, and the sixth CLBO crystal unit 104 to hold the fourth CLBO crystal 120, the fifth CLBO crystal 122, and the sixth CLBO crystal 124, respectively, and to store them in second containers 130.

[0134] Furthermore, the temperature regulator 94 controls the first heaters 92 of the first, second, and third CLBO crystal units 74, 76, and 78, respectively, raising the temperatures of the first, second, and third CLBO crystals 50, 52, and 54 to 150°C according to a predetermined schedule. Similarly, the temperature regulator 94 controls the second heaters 142 of the fourth, fifth, and sixth CLBO crystal units 100, 102, and 104, respectively, raising the temperatures of the fourth, fifth, and sixth CLBO crystals 120, 122, and 124 to 150°C according to a predetermined schedule.

[0135] Furthermore, the controller 22 introduces N 2 gas from the first purge gas inlet pipe 70 and discharges N 2 gas from the first purge gas outlet pipe 72 , thereby purging N 2 gas inside the wavelength conversion box 42 at a predetermined time and flow rate.

[0136] Furthermore, the control unit 22 purges Ar gas at a predetermined time and flow rate through the first containers 80 of the first, second, and third CLBO crystal units 74, 76, and 78. Similarly, the control unit 22 purges Ar gas at a predetermined time and flow rate through the second containers 130 of the fourth, fifth, and sixth CLBO crystal units 100, 102, and 104.

[0137] In addition, with Figure 2 Similarly to the example shown, stage controller 112 places first, second, and third CLBO crystal units 74, 76, and 78 on the optical path of the laser beam. Controller 22 uses first, second, and third CLBO crystal units 74, 76, and 78 to generate ultraviolet light.

[0138] During the period of using the first CLBO crystal unit 74, the second CLBO crystal unit 76, and the third CLBO crystal unit 78 to generate ultraviolet light, the control unit 22 also continuously maintains the temperature of each second heater 142 of the fourth CLBO crystal unit 100, the fifth CLBO crystal unit 102, and the sixth CLBO crystal unit 104, as well as the gas flow inside each second container 130.

[0139] When the life of first CLBO crystal 50 has reached the end of its life, stage controller 112 controls first stage 106 to move movable portion 152, thereby removing first CLBO crystal 50 of first CLBO crystal unit 74 from the laser beam path and inserting fourth CLBO crystal 120 of fourth CLBO crystal unit 100 into the laser beam path. Thus, wavelength conversion system 14 performs wavelength conversion using fourth CLBO crystal 120 instead of first CLBO crystal 50.

[0140] When the life of second CLBO crystal 52 reaches the end of its life, stage controller 112 controls second stage 108 to move movable portion 156, thereby removing second CLBO crystal 52 of second CLBO crystal unit 76 from the laser light path and inserting fifth CLBO crystal 122 of fifth CLBO crystal unit 102 into the laser light path. Thus, wavelength conversion system 14 performs wavelength conversion using fifth CLBO crystal 122 instead of second CLBO crystal 52.

[0141] When the life of third CLBO crystal 54 reaches the end of its life, stage controller 112 controls third stage 110 to move movable portion 160, thereby removing third CLBO crystal 54 of third CLBO crystal unit 78 from the laser light path and inserting sixth CLBO crystal 124 of sixth CLBO crystal unit 104 into the laser light path. Thus, wavelength conversion system 14 performs wavelength conversion using sixth CLBO crystal 124 instead of third CLBO crystal 54.

[0142] 4.2.1 Control of crystal replacement

[0143] The details of crystal replacement control will be described. Figure 5 1A is a flowchart showing an example of a control method of the solid-state laser system 1A by the control unit 22 when the crystal is replaced. Here, an example of replacing the second CLBO crystal 52 with the fifth CLBO crystal 122 will be described.

[0144] In step S1, the control unit 22 starts outputting pulsed laser light with a wavelength of approximately 193 nm from the solid-state laser system 1A. Here, the stage controller 112 controls the first stage 106, the second stage 108, and the third stage 110 to position the first, second, and third CLBO crystal units 74, 76, and 78 on the optical path of the laser light. Concomitantly, the fourth, fifth, and sixth CLBO crystal units 100, 102, and 104 are positioned outside the optical path of the laser light.

[0145] Therefore, the first, second, and third CLBO crystals 50, 52, and 54 are positioned on the laser light path, while the fourth, fifth, and sixth CLBO crystals 120, 122, and 124 are positioned outside the laser light path. Solid-state laser system 1A uses the first, second, and third CLBO crystals 50, 52, and 54 positioned on the laser light path to perform wavelength conversion, outputting pulsed laser light with a wavelength of approximately 193 nm.

[0146] The first, second, and third CLBO crystal units 74, 76, and 78, which are located on the laser light path, are referred to as driver units. Furthermore, the fourth, fifth, and sixth CLBO crystal units 100, 102, and 104, which are located outside the laser light path, are referred to as backup units. When the driver units used for wavelength conversion in solid-state laser system 1A reach the end of their life, wavelength conversion is performed using the backup units.

[0147] In step S2, the control unit 22 determines whether the life of the first CLBO crystal 50 of the drive unit held by the movable portion 152 of the first stage 106 is about to end. Furthermore, the control unit 22 determines whether the life of the second CLBO crystal 52 of the drive unit held by the movable portion 156 of the second stage 108 is about to end. Similarly, the control unit 22 determines whether the life of the third CLBO crystal 54 of the drive unit held by the movable portion 160 of the third stage 110 is about to end.

[0148] If the first CLBO crystal 50, the second CLBO crystal 52, and the third CLBO crystal 54 are not nearing the end of their life, the control unit 22 repeats the process of step S2. Here, the control unit 22 determines that the second CLBO crystal 52 is nearing the end of its life.

[0149] In step S3, the control unit 22 determines whether the fifth CLBO crystal 122 is placed (held) on the second crystal holder 140 of the fifth CLBO crystal unit 102, which is a preliminary unit held on the movable portion 156 of the second stage 108. If the fifth CLBO crystal 122 is not placed on the second crystal holder 140, the control unit 22 proceeds to step S4. If the fifth CLBO crystal 122 is placed on the second crystal holder 140, the control unit 22 proceeds to step S5.

[0150] In step S4, the control unit 22 displays on a display unit (not shown) that the second CLBO crystal 52 of the driving unit is about to reach the end of its life, thereby requesting the operator to place the fifth CLBO crystal 122 as a spare unit. Then, the control unit 22 performs the process of step S3.

[0151] In step S5, the control unit 22 starts the temperature control and dehydration process of the fifth CLBO crystal unit 102 as a spare unit. The temperature control and dehydration process is an example of the "dehydration treatment" of the present disclosure.

[0152] As a preliminary unit temperature control, temperature regulator 94 performs a heat treatment to heat fifth CLBO crystal 122. Specifically, temperature regulator 94 controls second heater 142 of fifth CLBO crystal unit 102 to raise the temperature of fifth CLBO crystal 122 to 150°C at a rate of 1°C / min. Temperature regulator 94 then maintains the temperature of fifth CLBO crystal 122 at 150°C until the end of its life.

[0153] Furthermore, as a dehydration step for the preparatory unit, the controller 22 implemented atmospheric flow. Specifically, the controller 22 continuously flowed atmospheric air through the third purge gas inlet pipe 136 and the third purge gas outlet pipe 138 of the fifth CLBO crystal unit 102 for 48 hours within the second container 130 of the fifth CLBO crystal unit 102, thereby fully dehydrating the unit.

[0154] Then, as a dehydration step for the preparatory unit, the control unit 22 implements an inert gas flow process. Specifically, the control unit 22 causes an inert gas with a low dew point temperature (e.g., Ar, Ne) to flow continuously for 48 hours within the second container 130 of the fifth CLBO crystal unit 102, thereby drying the crystal. Here, Ar gas is used as the inert gas. Alternatively, the atmospheric dehydration step can be omitted, and the crystal can be dried solely by the inert gas dehydration step.

[0155] In addition, when the fifth CLBO crystal 122 is placed in the spare unit in advance, the temperature control and dehydration process may be started just before the second CLBO crystal 52 of the driving unit reaches the end of its life.

[0156] In step S6, the control unit 22 determines whether the second CLBO crystal 52 of the drive unit has reached the end of its life. If the second CLBO crystal 52 has not reached the end of its life, the control unit 22 repeats the process of step S6. If the second CLBO crystal 52 has reached the end of its life, the control unit 22 proceeds to step S7.

[0157] In step S7, the control unit 22 stops the input of laser light to the wavelength conversion system 14. For example, the control unit 22 stops the operation of the first solid-state laser device 10 and the second solid-state laser device 12. The control unit 22 may also stop the input of laser light to the wavelength conversion system 14 by closing a shutter (not shown).

[0158] In step S8 , the stage controller 112 controls the actuator (not shown) of the second stage 108 to remove the second CLBO crystal 52 of the driving unit from the optical path of the laser beam and insert the fifth CLBO crystal 122 of the standby unit into the optical path of the laser beam.

[0159] In step S9, the control unit 22 determines whether the dehydration process of the preparatory unit is complete. If the 48 hours of atmospheric flow and the 48 hours of inert gas flow started in step S5 have ended, the control unit 22 proceeds to step S10. If the 48 hours of atmospheric flow and the 48 hours of inert gas flow started in step S5 have not ended, the control unit 22 repeats the process of step S9.

[0160] In step S10, the control unit 22 starts inputting laser light into the wavelength conversion system 14. That is, the control unit 22 starts the operation of the first solid-state laser device 10 and the second solid-state laser device 12. Furthermore, the control unit 22 controls a shutter (not shown) to block laser light emitted from the solid-state laser system 1A.

[0161] In step S11, the control unit 22 adjusts the phase matching angle of the fifth CLBO crystal 122 of the fifth CLBO crystal unit 102, which is a new drive unit. Figure 3 Although not shown in the figure, the 5th CLBO crystal unit 102 includes an HVθ stage.

[0162] The control unit 22 controls the HVθ stage of the fifth CLBO crystal unit 102 based on the detection results of an energy sensor (not shown) that measures the energy of the laser light emitted from the third window 48. The control unit 22 adjusts the phase matching angle of the fifth CLBO crystal 122 to maximize the energy after wavelength conversion.

[0163] Finally, in step S12 , the control unit 22 controls a gate (not shown) to start outputting pulsed laser light having a wavelength of approximately 193 nm from the solid-state laser system 1A.

[0164] 4.2.2 Determining the Timing of Starting Preparation for the Preparatory Unit

[0165] The control unit 22 determines the timing to start preparation of the preparatory unit based on the parameters of the laser. Here, the control unit 22 detects the timing when the drive unit is about to reach the end of its life based on at least one of the following (1) to (5) and starts preparation of the preparatory unit (storage, temperature control, dehydration process).

[0166] (1) Detection based on laser irradiation time

[0167] The total laser irradiation time of the CLBO crystal from the start of the driver unit operation is measured to detect when the specified time has been reached. For example, the maximum total laser irradiation time for the CLBO crystal is 4000 hours, and the specified time is 3200 hours, which is 80% of 4000 hours.

[0168] (2) Detection based on the number of pulses

[0169] The number of laser pulses irradiating the CLBO crystal from the start of the driver unit is counted, and the timing of reaching the specified number of pulses is detected. For example, the maximum number of total pulses of the CLBO crystal is 20 billion (20×10 9 ), the prescribed number of times is 80% of 20 billion, that is, 16 billion.

[0170] (3) Detection based on the laser output after wavelength conversion

[0171] A first energy sensor (not shown) is provided downstream of the wavelength conversion box 42 to detect when the pulse energy of the wavelength-converted light falls below a threshold value. The threshold value is, for example, 80 nW.

[0172] (4) Detection based on the conversion efficiency during wavelength conversion

[0173] A first energy sensor (not shown) is provided downstream of the wavelength conversion box 42, and a second energy sensor (not shown) is provided upstream of the wavelength conversion box 42. Assuming that the output of the first energy sensor is E out The output of the second energy sensor is E in When the wavelength conversion efficiency E is detected out / E in For example, when the output of the third CLBO crystal 54 is E out The input of the first CLBO crystal 50 is E in When , the threshold is 1%.

[0174] (5) Detection based on the number of times the incident point moves

[0175] The incident point of the laser beam on the incident surface of the CLBO crystal is locally contaminated. Therefore, if the contamination progresses to a certain extent, the crystal is moved using a two-axis stage to move the incident point.

[0176] Figure 6 : is a diagram showing the incident surface of the laser beam of the second CLBO crystal 52. Figure 6 In, with Figure 1 Similarly, the direction of laser travel is set to Z direction, a direction perpendicular to the Z direction is set to V direction, and a direction perpendicular to the V direction and the Z direction is set to H direction. Initially, the laser is incident on point P1 for the second CLBO crystal 52 and used. Then, after the contamination of point P1 develops, the second CLBO crystal 52 is moved in the H direction by the first HVθ stage 66, and the laser is incident on point P2 and used. Whenever the contamination of the incident point develops, the second CLBO crystal 52 is moved in the H direction or V direction, and the incident point is switched to point P3, P4, ..., P N-1 、P N .

[0177] The timing when the number of times the incident point moves reaches a predetermined number is detected. When the total number of incident points is N, the total number of moves is (N-1), and the predetermined number is, for example, (N-2).

[0178] Here, the movement of the incident point of the second CLBO crystal 52 is described, but the same applies to the first CLBO crystal 50 , the third CLBO crystal 54 , the fourth CLBO crystal 120 , the fifth CLBO crystal 122 , and the sixth CLBO crystal 124 .

[0179] For example, a biaxial (ZY plane) stage (not shown) may be provided between movable portion 152 and first CLBO crystal unit 74, or between movable portion 152 and rail 150, thereby enabling movement of the incident point on first CLBO crystal 50. In this case, assuming the total number of incident points on the biaxial stage (not shown) is N, the predetermined number may be set to, for example, (N-2).

[0180] (6) Detection based on laser output before wavelength conversion

[0181] A first energy sensor (not shown) is located downstream of the wavelength conversion box 42, and a second energy sensor (not shown) is located upstream of the wavelength conversion box 42. When the energy before wavelength conversion is controlled to maintain a constant energy after wavelength conversion, the energy before wavelength conversion increases as the CLBO crystal degrades. Therefore, the timing when the energy before wavelength conversion exceeds a threshold is detected. For example, the threshold value for the energy of a pulsed laser with a wavelength of approximately 515 nm input to the wavelength conversion box 42 is 8 W.

[0182] 4.3 Action / Effect

[0183] As described above, according to the solid-state laser system 1A, the crystal can be replaced for each unit simply by moving the movable portion of the stage, thereby shortening the replacement time.

[0184] Furthermore, since preparations for the crystal such as dehydration have already begun when the movable portion of the stage is moved, the replacement time can be further shortened.

[0185] Furthermore, a crystal newly inserted into the optical path via the stage can be arranged at substantially the same position as the crystal removed from the optical path, thereby shortening the time required to adjust the phase matching angle.

[0186] 5. Implementation Method 2

[0187] 5.1 Structure

[0188] Figure 7 1B is a diagram schematically showing the configuration of a solid-state laser system 1B according to a second embodiment. Figure 3 The differences from the solid-state laser system 1A shown will be described.

[0189] Figure 7 The solid-state laser system 1B shown includes a seventh CLBO crystal unit 200 , an eighth CLBO crystal unit 202 , a fourth stage 204 , a third high-reflection mirror 240 , and a fourth dichroic mirror 242 .

[0190] The fourth stage 204 includes a rail 206 extending in the Y direction and a movable portion 208 held on the rail 206 so as to be movable in the Y direction along the rail 206. The seventh CLBO crystal unit 200 and the eighth CLBO crystal unit 202 are held on the movable portion 208 side by side in the Y direction.

[0191] The fourth stage 204 includes an actuator (not shown). The actuator (not shown) is connected to the stage controller 112 .

[0192] The seventh CLBO crystal unit 200 includes a fourth container 210, a third entrance window 212, and a third exit window 214. The fourth container 210 is an example of the "first container" of the present disclosure. The third entrance window 212 is an example of the "first entrance window" of the present disclosure. Furthermore, the third exit window 214 is an example of the "first exit window" of the present disclosure.

[0193] The fourth container 210 contains a plurality of CLBO crystals. Here, the fourth container 210 includes three CLBO crystals arranged in series, namely, a seventh CLBO crystal 216, an eighth CLBO crystal 218, and a ninth CLBO crystal 220. The seventh CLBO crystal 216 is an example of the "first nonlinear crystal" of the present disclosure.

[0194] Of the 7th CLBO crystal 216, 8th CLBO crystal 218, and 9th CLBO crystal 220 arranged in series, the first 7th CLBO crystal 216 and the third 9th CLBO crystal 220 are wavelength conversion crystals with type 1 phase matching conditions. On the other hand, the second 8th CLBO crystal 218 is a wavelength conversion crystal with type 2 phase matching conditions.

[0195] The seventh CLBO crystal 216, the eighth CLBO crystal 218, and the ninth CLBO crystal 220 are each held by the first crystal holder 90. The seventh CLBO crystal 216, the eighth CLBO crystal 218, and the ninth CLBO crystal 220 each have a first heater 92. The third entrance window 212, the seventh CLBO crystal 216, the eighth CLBO crystal 218, the ninth CLBO crystal 220, and the third exit window 214 are arranged in series, side by side in the X direction.

[0196] The eighth CLBO crystal unit 202 includes a fifth container 222, a fourth entrance window 224, and a fourth exit window 226. The fifth container 222 is an example of the "second container" of the present disclosure. The fourth entrance window 224 is an example of the "second entrance window" of the present disclosure. Furthermore, the fourth exit window 226 is an example of the "second exit window" of the present disclosure.

[0197] The fifth container 222 contains a plurality of CLBO crystals. Here, the fifth container 222 includes three CLBO crystals arranged in series, namely, a tenth CLBO crystal 228, an eleventh CLBO crystal 230, and a twelfth CLBO crystal 232. The tenth CLBO crystal 228 is an example of the "second nonlinear crystal" of the present disclosure.

[0198] The tenth CLBO crystal 228 generates the same wavelength as the seventh CLBO crystal 216. The eleventh CLBO crystal 230 generates the same wavelength as the eighth CLBO crystal 218. The twelfth CLBO crystal 232 generates the same wavelength as the ninth CLBO crystal 220.

[0199] The tenth CLBO crystal 228 and the twelfth CLBO crystal 232 are wavelength conversion crystals having a phase matching condition of type 1. On the other hand, the eleventh CLBO crystal 230 is a wavelength conversion crystal having a phase matching condition of type 2.

[0200] Alternatively, the seventh CLBO crystal 216 and the eighth CLBO crystal 218 may be wavelength conversion crystals having a phase matching condition of type 1, and the ninth CLBO crystal 220 may be wavelength conversion crystals having a phase matching condition of type 2. In this case, the tenth CLBO crystal 228 and the eleventh CLBO crystal 230 may be wavelength conversion crystals having a phase matching condition of type 1, and the twelfth CLBO crystal 232 may be wavelength conversion crystals having a phase matching condition of type 2.

[0201] The tenth, eleventh, and twelfth CLBO crystals 228, 230, and 232 are each held in a second crystal holder 140. The second crystal holder 140 is an example of a "second crystal holder" in the present disclosure. The tenth, eleventh, and twelfth CLBO crystals 228, 230, and 232 each have a second heater 142. The fourth entrance window 224, the tenth, eleventh, and twelfth CLBO crystals 228, 230, and 232 are arranged in series, side by side, in the X direction.

[0202] The third high-reflection mirror 240 is arranged to highly reflect the second pulsed laser light output from the second solid-state laser device 12 and incident from the second window 46 , and to cause the second pulsed laser light to enter the fourth dichroic mirror 242 .

[0203] The fourth dichroic mirror 242 is coated with a film that highly transmits the pulsed laser light having a wavelength of approximately 515 nm output from the first solid-state laser device 10 and incident through the first window 44, and highly reflects the second pulsed laser light having a wavelength of approximately 1553 nm. The fourth dichroic mirror 242 is configured so that the pulsed laser light having a wavelength of approximately 515 nm and the second pulsed laser light are incident on the seventh CLBO crystal unit 200 or the eighth CLBO crystal unit 202 with their optical path axes aligned.

[0204] A collimating lens (not shown) may be disposed on the optical path between the first window 44 and the fourth dichroic mirror 242 to collimate the pulsed laser light. Furthermore, a BEX (Beam Expander) lens (not shown) or a condenser lens (not shown) may be disposed on the optical path between the third high-reflection mirror 240 and the fourth dichroic mirror 242 to adjust the beam diameter of the pulsed laser light. The BEX lens may be composed of a pair of concave and convex lenses (not shown).

[0205] exist Figure 7 In the example shown, the seventh CLBO crystal unit 200 is arranged on the optical path of the laser light, and the eighth CLBO crystal unit 202 is arranged outside the optical path of the laser light. Figure 8It shows Figure 7 The state shown is a diagram showing the state after the movable part 208 moves. Figure 8 In the example shown, the seventh CLBO crystal unit 200 is arranged outside the optical path of the laser light, and the eighth CLBO crystal unit 202 is arranged on the optical path of the laser light.

[0206] 5.2 Action

[0207] The operator has previously caused the first crystal holders 90 of the seventh CLBO crystal unit 200 to hold the seventh CLBO crystal 216, the eighth CLBO crystal 218, and the ninth CLBO crystal 220, respectively, and to store them in the fourth container 210. Similarly, the operator has caused the second crystal holders 140 of the eighth CLBO crystal unit 202 to hold the tenth CLBO crystal 228, the eleventh CLBO crystal 230, and the twelfth CLBO crystal 232, and to store them in the fifth container 222.

[0208] Furthermore, the temperature regulator 94 controls the first heaters 92 for the seventh, eighth, and ninth CLBO crystals 216, 218, and 220, raising the temperature to 150° C. according to a predetermined procedure. Similarly, the temperature regulator 94 controls the second heaters 142 for the tenth, eleventh, and twelfth CLBO crystals 228, 230, and 232, raising the temperature to 150° C. according to a predetermined procedure.

[0209] Next, the control unit 22 purges N2 gas at a predetermined time and flow rate inside the wavelength conversion box 42. Furthermore, the control unit 22 purges Ar gas at a predetermined time and flow rate inside the fourth container 210 of the seventh CLBO crystal unit 200 and the fifth container 222 of the eighth CLBO crystal unit 202.

[0210] like Figure 7 As shown, the stage controller 112 arranges the seventh CLBO crystal 216, the eighth CLBO crystal 218, and the ninth CLBO crystal 220 on the optical path of the laser light.

[0211] In this state, the control unit 22 generates ultraviolet light. Specifically, the control unit 22 directs pulsed laser light having a wavelength of approximately 515 nm into the first window 44 via the first solid-state laser device 10, and directs second pulsed laser light having a wavelength of approximately 1553 nm into the second window 46 via the second solid-state laser device 12. Consequently, the pulsed laser light having a wavelength of approximately 515 nm and the second pulsed laser light having a wavelength of approximately 1553 nm are incident on the seventh CLBO crystal 216 from the fourth dichroic mirror 242 at approximately the same time and along the same optical path axis.

[0212] The incident angle of the seventh CLBO crystal 216 is adjusted so that the pulsed laser light with a wavelength of approximately 515 nm satisfies the phase matching condition. As a result, the seventh CLBO crystal 216 generates a second harmonic of the pulsed laser light with a wavelength of approximately 515 nm, namely, a pulsed laser light with a wavelength of approximately 258 nm. Consequently, the seventh CLBO crystal 216 outputs pulsed laser light with a wavelength of approximately 258 nm and pulsed laser light with a wavelength of approximately 1553 nm.

[0213] The pulse laser light with a wavelength of approximately 258 nm and the pulse laser light with a wavelength of approximately 1553 nm are incident on the eighth CLBO crystal 218 approximately simultaneously and along approximately the same optical path axis.

[0214] The incident angle of the eighth CLBO crystal 218 is adjusted so that the pulsed laser light with a wavelength of approximately 258 nm and the pulsed laser light with a wavelength of approximately 1553 nm meet the phase matching condition. As a result, the eighth CLBO crystal 218 generates a pulsed laser light with a wavelength of approximately 221 nm, which is the sum frequency of the pulsed laser light with a wavelength of approximately 258 nm and the pulsed laser light with a wavelength of approximately 1553 nm. Therefore, the eighth CLBO crystal 218 outputs pulsed laser light with a wavelength of approximately 221 nm, a pulsed laser light with a wavelength of approximately 258 nm, and a pulsed laser light with a wavelength of approximately 1553 nm.

[0215] A pulse laser with a wavelength of approximately 221 nm, a pulse laser with a wavelength of approximately 258 nm, and a pulse laser with a wavelength of approximately 1553 nm are incident on the ninth CLBO crystal 220 .

[0216] The incident angle of the ninth CLBO crystal 220 is adjusted so that the pulsed laser light with a wavelength of approximately 221 nm and the pulsed laser light with a wavelength of approximately 1553 nm meet phase matching conditions. As a result, the ninth CLBO crystal 220 generates a pulsed laser light with a wavelength of approximately 193 nm, which is the sum frequency of the pulsed laser light with a wavelength of approximately 221 nm and the pulsed laser light with a wavelength of approximately 1553 nm. This pulsed laser light with a wavelength of approximately 193 nm is output from the wavelength conversion system 14 via the third exit window 214 and the third window 48.

[0217] In this way, during the period when ultraviolet light is generated by the 7th CLBO crystal 216, the 8th CLBO crystal 218 and the 9th CLBO crystal 220 of the 7th CLBO crystal unit 200, the control unit 22 also continues to maintain the temperature of each second heater 142 of the 8th CLBO crystal unit 202 and the gas flow inside the 5th container 222.

[0218] When any of the seventh, eighth, and ninth CLBO crystals 216, 218, and 220 reach the end of their lifespan, the stage controller 112 controls the fourth stage 204 to move the movable portion 208, thereby removing the seventh, eighth, and ninth CLBO crystals 216, 218, and 220 of the seventh CLBO crystal unit 200 from the laser light path. Furthermore, the stage controller 112 inserts the tenth, eleventh, and twelfth CLBO crystals 228, 230, and 232 of the eighth CLBO crystal unit 202 into the laser light path. Thus, the wavelength conversion system 14 performs wavelength conversion using the tenth, eleventh, and twelfth CLBO crystals 228, 230, and 232 instead of the seventh, eighth, and ninth CLBO crystals 216, 218, and 220.

[0219] 5.3 Action / Effect

[0220] As described above, according to the solid-state laser system 1B, the same operations and effects as those of the first embodiment are achieved.

[0221] Furthermore, since the optical path is coupled before the input of the CLBO crystal, the wavelength conversion CLBO crystal unit and the spare CLBO crystal unit can each be configured with multiple (here, three) CLBO crystals in series, which enables the wavelength conversion system 14 to be miniaturized.

[0222] Furthermore, since a plurality of CLBO crystals are arranged in one CLBO crystal unit, the number of stages and piping can be reduced, and the device can be miniaturized.

[0223] Furthermore, by replacing one CLBO crystal unit, multiple CLBO crystals can be replaced, thereby reducing the time required for maintenance.

[0224] 6. Method for manufacturing electronic devices

[0225] Figure 9 300 is a diagram schematically showing a configuration example of the exposure device 302. The method for manufacturing an electronic device is realized by the solid-state laser system 1, the excimer amplifier 300, and the exposure device 302.

[0226] Excimer amplifier 300 is, for example, an ArF excimer laser device that amplifies laser light. A hybrid laser device is formed using the solid-state laser system 1 and the excimer amplifier 300. The excimer amplifier 300 amplifies the pulsed laser light emitted from the solid-state laser system 1. The pulsed laser light amplified by the excimer amplifier 300 is input to the exposure device 302 and used as exposure light.

[0227] 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 excimer laser light incident from the excimer amplifier 300. The projection optical system 306 performs a reduced projection on the laser light passing through the mask so that it is imaged on a workpiece (not shown) arranged on the workpiece stage WT. The workpiece is a photosensitive substrate such as a semiconductor wafer coated with photoresist. The exposure device 302 causes the mask stage RT and the workpiece stage WT to move synchronously and parallely, thereby exposing the workpiece to the laser light reflecting 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. The solid-state laser system 1 can also be the solid-state laser system 1A or 1B described in each embodiment.

[0228] 7. Others

[0229] 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.

[0230] 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 laser system comprising: a solid-state laser device that outputs laser light; a first crystal holder that holds a first nonlinear crystal disposed on an optical path of the laser beam; a first heater for heating the first nonlinear crystal; a first container that houses the first heater and the first crystal holder and includes a first incident window for the laser beam to be incident on and a first exit window for the laser beam to be emitted from; a first gas introduction pipe for introducing a first gas into the first container; a first gas exhaust pipe for exhausting the first gas in the first container; a second crystal holder that holds a second nonlinear crystal disposed outside the optical path of the laser beam; a second heater for heating the second nonlinear crystal; a second container that houses the second heater and the second crystal holder and includes a second incident window for incident laser light and a second exit window for exiting laser light when the container is arranged on an optical path of the laser light; a second gas introduction pipe for introducing the first gas into the second container; a second gas exhaust pipe for exhausting the first gas in the second container; a stage that holds the first container and the second container; and a controller that controls the stage to remove the first nonlinear crystal from the optical path of the laser light and insert the second nonlinear crystal into the optical path of the laser light; When the first nonlinear crystal is arranged on the optical path of the laser beam, the controller performs a dehydration process on the second nonlinear crystal. The controller implements the following processing as the dehydration processing: performing a heat treatment on the second nonlinear crystal; and an inert gas flow treatment in which an inert gas having a dew point temperature lower than that of the atmosphere is introduced into the second container and the inert gas is discharged from the second container; The controller performs, as the dehydration process, an atmospheric air flow process of introducing the atmospheric air into the second container and exhausting the atmospheric air from the second container before the inert gas flow process.

2. The laser system according to claim 1, wherein: The controller determines whether the second nonlinear crystal is held by the second crystal holder before performing the dehydration process.

3. The laser system according to claim 1, wherein: The first container and the second container respectively accommodate a plurality of nonlinear crystals arranged in series.

4. The laser system according to claim 3, wherein: The first container and the second container respectively accommodate three nonlinear crystals arranged in series.

5. The laser system according to claim 4, wherein: The nonlinear crystal is CLBO (CsLiB6O 10 ) crystal.

6. The laser system according to claim 5, wherein: The first CLBO crystal and the third CLBO crystal of the three CLBO crystals configured in series perform type 1 phase matching, and the second CLBO crystal performs type 2 phase matching.

7. The laser system according to claim 6, wherein: The movable portion of the stage moves in a direction perpendicular to the direction of the series connection.

8. The laser system of claim 1, wherein: The laser system has: a third container for accommodating the first container and the second container; a third gas introduction pipe for introducing the second gas into the third container; and a third gas exhaust pipe for exhausting the second gas in the third container.

9. The laser system according to claim 8, wherein: The first gas is Ar gas, and the second gas is N 2 gas.

10. The laser system of claim 1, wherein: The controller determines a timing for starting a dehydration process of the second nonlinear crystal based on parameters of the laser.

11. The laser system of claim 10, wherein: The parameter is the irradiation time of the laser beam incident on the first nonlinear crystal.

12. The laser system of claim 10, wherein: The parameter is the number of pulses of the laser light incident on the first nonlinear crystal.

13. The laser system of claim 10, wherein: The parameter is energy of the laser light incident on the first nonlinear crystal after wavelength conversion.

14. The laser system of claim 10, wherein: The parameter is the conversion efficiency of the laser light incident on the first nonlinear crystal.

15. The laser system of claim 10, wherein: The parameter is the number of times the incident point of the laser beam incident on the first nonlinear crystal moves.

16. The laser system of claim 10, wherein: The parameter is the energy of the laser light incident on the first nonlinear crystal before wavelength conversion.

17. A method for manufacturing an electronic device, comprising the following steps: Generate excimer laser light through the laser system, outputting the excimer laser to an exposure device, exposing the excimer laser on a photosensitive substrate in the exposure device to manufacture an electronic device, The laser system comprises: a solid-state laser device that outputs laser light; a first crystal holder that holds a first nonlinear crystal disposed on an optical path of the laser beam; a first heater for heating the first nonlinear crystal; a first container that houses the first heater and the first crystal holder and includes a first incident window for the laser beam to be incident on and a first exit window for the laser beam to be emitted from; a first gas introduction pipe for introducing a first gas into the first container; a first gas exhaust pipe for exhausting the first gas in the first container; a second crystal holder that holds a second nonlinear crystal disposed outside the optical path of the laser beam; a second heater for heating the second nonlinear crystal; a second container that houses the second heater and the second crystal holder and includes a second incident window for incident laser light and a second exit window for exiting laser light when the container is arranged on an optical path of the laser light; a second gas introduction pipe for introducing the first gas into the second container; a second gas exhaust pipe for exhausting the first gas in the second container; a stage holding the first container and the second container; a controller that controls the stage to remove the first nonlinear crystal from the optical path of the laser light and insert the second nonlinear crystal into the optical path of the laser light; and an excimer amplifier that amplifies the laser light emitted from the first emission window or the second emission window, When the first nonlinear crystal is arranged on the optical path of the laser beam, the controller performs a dehydration process on the second nonlinear crystal. The controller implements the following processing as the dehydration processing: performing a heat treatment on the second nonlinear crystal; and an inert gas flow treatment in which an inert gas having a dew point temperature lower than that of the atmosphere is introduced into the second container and the inert gas is discharged from the second container; The controller performs, as the dehydration process, an atmospheric air flow process of introducing the atmospheric air into the second container and exhausting the atmospheric air from the second container before the inert gas flow process.

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