Laser system and method for manufacturing electronic device

Abstract

A laser system is provided with: a laser oscillator system that outputs a first pulse laser beam in a first polarization direction and a second pulse laser beam in a second polarization direction that is rotated by 45 degrees in a first rotation direction with respect to the first polarization direction; the beam combiner is used for combining the first pulse laser and the second pulse laser; the beam combiner is provided with: a first polarizing plate; a first Faraday rotator that rotates the polarization direction of the first pulse laser beam that has passed through the first polarizing plate by 45 degrees in the direction opposite to the first rotation direction; and a second polarizing plate that transmits the first pulse laser beam that has passed through the first Faraday rotator and reflects the second pulse laser beam. And the multi-pass Faraday mirror is used for reflecting the first pulse laser and the second pulse laser towards the second polarizer. The multi-pass Faraday mirror comprises a first Faraday material, an electromagnet and a plurality of reflectors, the processor controls current flowing through the electromagnet through the power supply, so that the current does not flow through the electromagnet when the first pulse laser penetrates through the multi-pass Faraday mirror, and current rotating 90 degrees in the polarization direction of the second pulse laser flows through the electromagnet when the second pulse laser penetrates through the first Faraday material.

Description

Technical Field

[0001] The present disclosure relates to a laser system and a method for manufacturing an electronic device. Background Art

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

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

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: International Publication No. 2021 / 108054

[0007] Patent Document 2: U.S. Patent Application Publication No. 2005 / 146769 Summary of the Invention

[0008] A laser system according to one aspect of the present disclosure comprises: a laser oscillator system that outputs a first pulsed laser in a first polarization direction and a second pulsed laser in a second polarization direction rotated 45 degrees in a first rotation direction relative to the first polarization direction; a beam combiner that combines the first pulsed laser and the second pulsed laser so that the first pulsed laser and the second pulsed laser propagate in a common direction, the beam combiner comprising: a first polarizer that transmits the first pulsed laser; a first Faraday rotator that rotates the polarization direction of the first pulsed laser after passing through the first polarizer by 45 degrees in a second rotation direction opposite to the first rotation direction; a second polarizer that transmits the first pulsed laser after passing through the first Faraday rotator and reflects the second pulsed laser; and a multi-pass Faraday mirror that The first pulse laser after passing through the second polarizer and the second pulse laser after being reflected by the second polarizer are reflected toward the second polarizer. The multi-pass Faraday mirror includes: a first Faraday material, through which the first pulse laser and the second pulse laser pass; an electromagnet, which applies a magnetic field to the first Faraday material; and a plurality of reflectors, which return the first pulse laser and the second pulse laser after passing through the first Faraday material to the first Faraday material; a power supply, which allows current to flow through the electromagnet; and a processor, which controls the current flowing through the electromagnet via the power supply, so that when the first pulse laser passes through the first Faraday material, current does not flow through the electromagnet, and when the second pulse laser passes through the first Faraday material, current that rotates the polarization direction of the second pulse laser by 90 degrees flows through the electromagnet.

[0009] Another aspect of the present disclosure provides a method for manufacturing an electronic device, including the following steps: generating laser light through a laser system, outputting the laser light to an exposure device, exposing the laser light on a photosensitive substrate in the exposure device to manufacture the electronic device, wherein the laser system comprises: a laser oscillator system, which outputs a first pulse laser light in a first polarization direction and a second pulse laser light in a second polarization direction rotated 45 degrees in a first rotation direction relative to the first polarization direction; a beam combiner, which combines the first pulse laser light and the second pulse laser light so that the first pulse laser light and the second pulse laser light propagate in a common direction, the beam combiner comprising: a first polarizer, which allows the first pulse laser light to pass through; a first Faraday rotator, which rotates the polarization direction of the first pulse laser light after passing through the first polarizer by 45 degrees in a second rotation direction opposite to the first rotation direction; and a second polarizer, which allows the first pulse laser light to pass through the first Faraday rotator. The first pulse laser passes through the first polarizer and reflects the second pulse laser; and a multi-pass Faraday mirror, which reflects the first pulse laser after passing through the second polarizer and the second pulse laser after being reflected by the second polarizer toward the second polarizer, the multi-pass Faraday mirror comprising: a first Faraday material, through which the first pulse laser and the second pulse laser pass; an electromagnet, which applies a magnetic field to the first Faraday material; and a plurality of reflecting mirrors, which return the first pulse laser and the second pulse laser after passing through the first Faraday material to the first Faraday material; a power supply, which causes current to flow through the electromagnet; and a processor, which controls the current flowing through the electromagnet via the power supply, so that when the first pulse laser passes through the first Faraday material, current does not flow through the electromagnet, and when the second pulse laser passes through the first Faraday material, current that rotates the polarization direction of the second pulse laser by 90 degrees flows through the electromagnet. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0011] Figure 1 The structure of a laser system of a comparative example is schematically shown.

[0012] Figure 2 It is an explanatory diagram showing a state in which the mirror of the beam combiner of the comparative example is arranged at the first position.

[0013] Figure 3 It is an explanatory diagram showing a state in which the mirror of the beam combiner of the comparative example is arranged at the second position.

[0014] Figure 4 The configuration of the laser system according to the first embodiment is schematically shown.

[0015] Figure 5 The structure of the beam combiner used in the first embodiment is schematically shown.

[0016] Figure 6It is an explanatory diagram showing the propagation of the first pulse laser light output from the first laser oscillator.

[0017] Figure 7 It is an explanatory diagram showing the propagation of the second pulsed laser light output from the second laser oscillator.

[0018] Figure 8 The structure of a multi-pass Faraday mirror according to a modified example of the first embodiment is schematically shown.

[0019] Figure 9 The configuration of the laser system according to the second embodiment is schematically shown.

[0020] Figure 10 It is an explanatory diagram showing the propagation of the second pulse laser light output from the third laser oscillator.

[0021] Figure 11 The configuration of the laser system according to the third embodiment is schematically shown.

[0022] Figure 12 It is an explanatory diagram showing the propagation of the first pulse laser light output from the first amplifier.

[0023] Figure 13 It is an explanatory diagram showing the propagation of the second pulse laser light output from the second amplifier.

[0024] Figure 14 The structure of the exposure device is schematically shown. DETAILED DESCRIPTION

[0025] - Contents - 1. Explanation of terms

[0026] 1.1 Faraday Materials

[0027] 1.2 Multi-pass Faraday mirror

[0028] 2. Overview of the Laser System of the Comparative Example

[0029] 2.1 Structure

[0030] 2.2 Action

[0031] 2.3 Topics

[0032] 3. Implementation Method 1

[0033] 3.1 Structure

[0034] 3.2 Action

[0035] 3.3 Effect

[0036] 3.4 Variations

[0037] 3.4.1 Structure

[0038] 3.4.2 Action

[0039] 3.4.3 Effect

[0040] 4. Implementation Method 2

[0041] 4.1 Structure

[0042] 4.2 Action

[0043] 4.3 Effect

[0044] 5. Implementation Method 3

[0045] 5.1 Structure

[0046] 5.2 Action

[0047] 5.3 Effect

[0048] 6. Regarding the manufacturing method of electronic devices

[0049] 7. Others

[0050] Hereinafter, 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. In addition, the structures and actions described in each embodiment are not necessarily required as the structures and actions of the present disclosure. In addition, the same reference numerals are used for the same components, and repeated descriptions are omitted.

[0051] 1. Explanation of terms

[0052] 1.1 Faraday Materials

[0053] Faraday materials are materials that produce the Faraday effect, a magneto-optical effect, when an external magnetic field is applied. While the Faraday effect can occur in any material, in this specification, it refers to materials that exhibit the Faraday effect in ultraviolet light (UV) wavelengths between 150 nm and 380 nm. In the deep ultraviolet region, candidate Faraday materials include calcium fluoride (CaF2), magnesium fluoride (MgF2), and synthetic quartz.

[0054] 1.2 Multi-pass Faraday mirror

[0055] A multi-pass Faraday mirror consists of a Faraday material, an electromagnet that applies a magnetic field to the Faraday material, and multiple mirrors that reflect light that has passed through the Faraday material back to the Faraday material. The mirrors are arranged so that the optical axis of the light entering the multi-pass Faraday mirror is aligned with the optical axis of the light exiting the mirror.

[0056] Light incident on a multi-pass Faraday mirror passes through the Faraday material an even number of times. During these passes, the Faraday effect rotates the polarization direction due to the magnetic field applied to the Faraday material by the electromagnet. By making light pass through the Faraday material multiple times, the magnetic field applied by the electromagnet can be reduced. Furthermore, the size of the Faraday material can be reduced. Furthermore, the reflector can also be a reflective coating. Reflective coatings that function as reflectors are included in the concept of "reflector."

[0057] 2. Overview of the Laser System of the Comparative Example

[0058] 2.1 Structure

[0059] Figure 1 This is a schematic diagram schematically illustrating the structure of a comparative example laser system 10. The comparative examples disclosed herein are methods known only to the applicant and are not publicly known examples recognized by the applicant. Laser system 10 includes a first laser oscillator LO1, a second laser oscillator LO2, a beam combiner 20, and a laser processor 220.

[0060] The first laser oscillator LO1 outputs a first pulsed laser beam 100 , and the second laser oscillator LO2 outputs a second pulsed laser beam 120 .

[0061] The beam combiner 20 combines the first pulse laser 100 and the second pulse laser 120 so that the first pulse laser 100 and the second pulse laser 120 propagate in a common direction.

[0062] The laser processor 220 alternately outputs the first pulsed laser 100 and the second pulsed laser 120 at the same repetition frequency, so that the laser system 10 outputs a pulsed laser having a repetition frequency that is twice the repetition frequency of the first pulsed laser 100 and the second pulsed laser 120. For example, when the repetition frequency of the first pulsed laser 100 and the second pulsed laser 120 is 6 kHz, the laser system 10 can output a pulsed laser having a repetition frequency of 12 kHz.

[0063] Figure 2 and Figure 3 : represents the structure of the beam combiner 20. In addition, Figure 2 as well as Figure 3 It is cited from Patent Document 1 Figure 6 A and Figure 6 B and the resulting figure.

[0064] The beam combiner 20 includes a mirror 200 and an actuator 210. Figure 2 and Figure 3In the figure, the solid arrows represent the propagation of effective pulsed laser light, and the dashed arrows represent the propagation of pulsed laser light when the mirror 200 is located at another position indicated by the dashed line. The first pulsed laser light 100 and the second pulsed laser light 120 are incident on the beam combiner 20 such that the angle θ between their respective optical axes is θ. Direction A is the direction in which the pulsed laser light is output from the laser system 10.

[0065] 2.2 Action

[0066] When the first pulse laser 100 outputted from the first laser oscillator LO1 is outputted from the laser system 10, a control signal is sent from the laser processor 220 to the actuator 210 so that the position of the mirror 200 of the beam combiner 20 becomes Figure 2 When the second pulse laser 120 outputted by the second laser oscillator LO2 is outputted from the laser system 10, a control signal is sent from the laser processor 220 to the actuator 210 so that the position of the mirror 200 of the beam combiner 20 becomes Figure 3 The second position is shown by the solid line.

[0067] The angle difference between the first position and the second position of the mirror 200 is θ / 2. The laser processor 220 alternately switches the position of the mirror 200 to the first position or the second position according to the pulsed laser light incident on the beam combiner 20, thereby outputting pulsed laser light at the repetition frequency of the first pulsed laser light 100 and the second pulsed laser light 120 from the laser system 10.

[0068] 2.3 Topics

[0069] The beam combiner 20 includes a movable portion for switching the position of the mirror 200 by the actuator 210 , but it is difficult to switch the position with good reproducibility at a high repetition frequency such as 12 kHz. Therefore, the position reproducibility of the pulsed laser output from the laser system 10 is poor.

[0070] It is desired to improve such a beam combiner 20 so that two pulse lasers propagate in a common direction and realize a laser system in which the position of the output pulse lasers is less likely to vary (excellent position reproducibility).

[0071] 3. Implementation Method 1

[0072] 3.1 Structure

[0073] Figure 4 The following schematically shows the configuration of a laser system 10A according to Embodiment 1. The laser system 10A includes a laser oscillator system 30 , a beam combiner 40 , and a laser processor 222 .

[0074] The laser oscillator system 30 includes a first laser oscillator LO1 and a second laser oscillator LO2. In the figure, "Laser Oscillator 1" indicates the first laser oscillator LO1, and "Laser Oscillator 2" indicates the second laser oscillator LO2. The first laser oscillator LO1 outputs a first pulsed laser light PL1 with a first polarization direction at an ultraviolet wavelength of 150 nm to 380 nm. The first laser oscillator LO1 can be a KrF excimer laser or an ArF excimer laser. Furthermore, the spectral linewidth of the first pulsed laser light PL1 can be narrowed to less than 1 pm.

[0075] The second laser oscillator LO2 outputs second pulsed laser light PL2 with an ultraviolet wavelength of 150 nm to 380 nm and a second polarization direction rotated 45 degrees counterclockwise relative to the first polarization direction. The counterclockwise direction is an example of a "first rotation direction" in this disclosure. The second laser oscillator LO2 can be a KrF excimer laser or an ArF excimer laser. Furthermore, the spectral linewidth of the second pulsed laser light PL2 can be narrowed to less than 1 pm.

[0076] The laser processor 222 functions as a control device for the laser system 10A. The laser processor 222 is a processing device that includes a storage device storing a control program and a CPU (Central Processing Unit) that executes the control program. The laser processor 222 is specifically configured or programmed to perform the various processes included in the present disclosure. The storage device is a tangible, non-transitory computer-readable medium, and includes, for example, a memory as a primary storage device and a storage unit as an auxiliary storage device. The computer-readable medium may be, for example, a semiconductor memory, a hard disk drive (HDD), a solid-state drive (SSD), or a combination thereof.

[0077] The beam combiner 40 includes a first polarizer 42, a Faraday rotator 44, a second polarizer 46, and a multi-pass Faraday mirror 48. In addition, the laser system 10A includes a power supply 50 for supplying current to the multi-pass Faraday mirror 48. The first laser oscillator LO1, the second laser oscillator LO2, and the power supply 50 are each controlled by the laser processor 222.

[0078] The first polarizing plate 42 is configured to transmit the first pulsed laser light PL1 . The first polarizing plate 42 may be, for example, a polarizing prism or a thin-film polarizing plate.

[0079] The Faraday rotator 44 is configured to transmit the first pulsed laser light PL1 after passing through the first polarizer 42. The Faraday rotator 44 is composed of a Faraday material 54, which rotates the polarization direction of the first pulsed laser light PL1 by 45 degrees clockwise when viewed in the direction of travel of the first pulsed laser light PL1, and a permanent magnet 56. The clockwise direction is an example of a "second rotation direction" in this disclosure. The Faraday material 54 can be, for example, CaF2, MgF2, or synthetic quartz. The permanent magnet 56 applies a magnetic field to the Faraday material 54. The Faraday rotator 44 is an example of a "first Faraday rotator" in this disclosure. The Faraday material 54 is an example of a "second Faraday material" in this disclosure, and the permanent magnet 56 is an example of a "first permanent magnet" in this disclosure.

[0080] The second polarizing plate 46 is arranged to transmit the first pulsed laser light PL1 after passing through the Faraday rotator 44 and reflect the second pulsed laser light PL2. The second polarizing plate 46 may be, for example, a polarizing prism or a thin-film polarizing plate.

[0081] The multi-pass Faraday mirror 48 is arranged so as to receive the first pulsed laser light PL1 that has passed through the second polarizing plate 46 .

[0082] Figure 5 A diagram showing the structure of a multi-pass Faraday mirror 48. The multi-pass Faraday mirror 48 includes a Faraday material 64 that rotates the polarization direction of the pulsed laser light PL 90 degrees clockwise when observing the direction in which the pulsed laser light PL travels; a coil 66 that constitutes an electromagnet; a high-reflection mirror 71; a high-reflection mirror 72; a high-reflection mirror 73; and a high-reflection mirror 74.

[0083] The Faraday material 64 may be, for example, CaF 2 , MgF 2 or synthetic quartz. The Faraday material 64 is an example of the “first Faraday material” in the present disclosure.

[0084] High reflector mirrors 71 to 74 are configured so that the pulse laser PL incident on the multi-pass Faraday mirror 48 is reflected by high reflector mirrors 71, 72, 73, and 74, and then reflected by high reflector mirrors 73, 72, and 71, and emitted coaxially with the incident pulse laser PL.

[0085] in addition, Figure 5 This example shows pulsed laser light PL passing through Faraday material 64 eight times (eight passes), but the number of passes can be an even number of four or greater. Pulsed laser light PL may be first pulsed laser light PL1 or second pulsed laser light PL2. High-reflection mirrors 71 to 74 are examples of "plurality of reflective mirrors" in this disclosure.

[0086] The power source 50 is connected to the coil 66. When current flows from the power source 50 to the coil 66, a magnetic field is applied to the Faraday material 64.

[0087] 3.2 Action

[0088] The laser processor 222 alternately outputs the first pulse laser PL1 and the second pulse laser PL2 from the laser oscillator system 30 at the same repetition frequency.

[0089] Figure 6 The figure shows the propagation of the first pulsed laser light PL1 output from the first laser oscillator LO1. The first pulsed laser light PL1, output from the first laser oscillator LO1 and having a first polarization direction, passes through the first polarizer 42. Furthermore, upon passing through the Faraday rotator 44, the polarization direction of the first pulsed laser light PL1 is rotated 45 degrees clockwise, becoming a third polarization direction. The double-headed arrow within the dashed circle in the figure indicates the direction of the polarization plane of the pulsed laser light PL, or the polarization direction, when the line of sight is aligned with the direction of travel of the pulsed laser light PL. After passing through the Faraday rotator 44, the first pulsed laser light PL1 passes through the second polarizer 46. After passing through the second polarizer 46, the first pulsed laser light PL1 is incident on the multi-pass Faraday mirror 48.

[0090] The first pulsed laser light PL1 incident on the multi-pass Faraday mirror 48 passes through the Faraday material 64 eight times and is reflected toward the second polarizer 46. At this time, the laser processor 222 does not allow current to flow through the coil 66 via the power supply 50. In other words, the electromagnet is turned off. In this case, the polarization direction of the first pulsed laser light PL1 does not rotate when passing through the multi-pass Faraday mirror 48. Therefore, the polarization direction of the first pulsed laser light PL1 output from the multi-pass Faraday mirror 48 remains unchanged in the third polarization direction.

[0091] The first pulsed laser light PL1 of the third polarization direction, reflected by the multi-pass Faraday mirror 48, passes through the second polarizer 46 and is rotated 45 degrees clockwise by the Faraday rotator 44 to the fourth polarization direction. The first pulsed laser light PL1 of the fourth polarization direction is reflected by the first polarizer 42 and output from the laser system 10A.

[0092] Figure 7 FIG4 shows the propagation of the second pulsed laser light PL2 output from the second laser oscillator LO2. The second pulsed laser light PL2 of the second polarization direction output from the second laser oscillator LO2 is reflected by the second polarizing plate 46. The second pulsed laser light PL2 then enters the multi-pass Faraday mirror 48.

[0093] The second pulsed laser light PL2 incident on the multi-pass Faraday mirror 48 passes through the Faraday material 64 eight times and is reflected toward the second polarizer 46. At this time, the laser processor 222 causes current to flow through the coil 66 via the power supply 50. In other words, the electromagnet is turned on. The second pulsed laser light PL2 passes through the Faraday material 64 eight times, thereby reducing the magnetic field generated by the electromagnet. This allows for a more compact electromagnet and reduces the current flowing through the coil 66.

[0094] The intensity of the magnetic field generated by the electromagnet is in the range of 0.005 T to 1.0 T. When the second pulsed laser light PL2 passes through the multi-pass Faraday mirror 48, its polarization direction rotates 90 degrees clockwise. Therefore, the polarization direction of the second pulsed laser light PL2 reflected by the multi-pass Faraday mirror 48 becomes the third polarization direction.

[0095] After being reflected by the multi-pass Faraday mirror 48, the second pulsed laser light PL2 of the third polarization direction passes through the second polarizer 46. The polarization direction is rotated 45 degrees clockwise by the Faraday rotator 44 to the fourth polarization direction. The second pulsed laser light PL2 of the fourth polarization direction is reflected by the first polarizer 42 and output from the laser system 10A.

[0096] The laser processor 222 turns off the electromagnet when the first pulsed laser light PL1 is incident on the multi-pass Faraday mirror 48, and turns on the electromagnet when the second pulsed laser light PL2 is incident on the multi-pass Faraday mirror 48. As a result, the first pulsed laser light PL1 of the first polarization direction and the second pulsed laser light PL2 of the second polarization direction output from the laser oscillator system 30 are combined in the beam combiner 40 and propagate in a common direction.

[0097] The combined first pulse laser light PL1 and second pulse laser light PL2 in the fourth polarization direction are alternately output from the laser system 10A.

[0098] The clockwise direction and the counterclockwise direction of the above embodiment can also function as the beam combiner 40 in the opposite direction. However, in this case, the polarization direction of the light passing through the second polarizer 46 is different from the above description by 90 degrees.

[0099] 3.3 Effect

[0100] According to the laser system 10A of the first embodiment, the following effects can be obtained.

[0101] [1] Combiner 40 does not have Figure 2 and Figure 3 Since the actuator 210 and the like shown are movable parts, the position reproducibility of the pulsed laser light PL (the first pulsed laser light PL1 and the second pulsed laser light PL2 ) output from the laser system 10A is high.

[0102] [2] In the multi-pass Faraday mirror 48, by passing the pulsed laser light multiple times, the electromagnet can be miniaturized and the current flowing through the coil 66 can be reduced.

[0103] [3] The laser system 10A can output pulsed laser light PL having the same polarization direction.

[0104] 3.4 Variations

[0105] 3.4.1 Structure

[0106] Figure 8 The structure of the multi-pass Faraday mirror 49 of a modified example of the first embodiment is shown. Figure 5 The multi-pass Faraday mirror 48 shown can be used Figure 8 A multi-pass Faraday mirror 49 is shown.

[0107] The multi-pass Faraday mirror 49 includes a Faraday material 65, a high-reflection mirror 81, and a coil 66 constituting an electromagnet. High-reflection coatings 82 and 83 are applied to a portion of the Faraday material 65, respectively, on a first surface 65a, which is the surface on which the pulsed laser light PL is incident, and on a second surface 65b, which is the surface from which the pulsed laser light PL is output toward the high-reflection mirror 81.

[0108] 3.4.2 Action

[0109] The pulsed laser light PL incident on the multi-pass Faraday mirror 49 enters the Faraday material 65 from the portion of the first surface 65a to which the high-reflection coating 82 is not applied. Then, after being reflected by the high-reflection coating 83 and the high-reflection coating 82, the pulsed laser light PL is output from the portion of the second surface 65b to which the high-reflection coating 83 is not applied.

[0110] The pulse laser light PL output from the second surface 65 b of the Faraday material 65 is reflected by the high reflection mirror 81 and then returns to the Faraday material 65 .

[0111] After being reflected by the high-reflection mirror 81, the pulsed laser light PL enters the Faraday material 65 from the portion of the second surface 65b not coated with the high-reflection coating 83. After being reflected by the high-reflection coatings 82 and 83, it is output from the portion of the first surface 65a not coated with the high-reflection coating 82. Reflection from the high-reflection coatings 82 and 83 is preferably two or more times each. In other words, the pulsed laser light PL preferably passes through the Faraday material 65 four or more times. The high-reflection mirror 81 and the high-reflection coatings 82 and 83 are examples of "plurality of reflectors" in this disclosure.

[0112] When the laser processor 222 causes current to flow through the coil 66 via the power supply 50, that is, when the electromagnet is turned on, the polarization direction of the pulsed laser light PL is rotated 90 degrees clockwise when passing through the multi-pass Faraday mirror 49. When the first pulsed laser light PL1 and the second pulsed laser light PL2 respectively pass through the Faraday material 65, the operation of controlling the current (the current of the electromagnet) flowing through the coil 66 via the power supply 50 to switch the electromagnet on and off is the same as in the first embodiment.

[0113] 3.4.3 Effect

[0114] The laser system 10A including the multi-pass Faraday mirror 49 of the modification can achieve the same effects as those of Embodiment 1. The multi-pass Faraday mirror 49 of the modification can reduce the number of high-reflection mirrors compared to the multi-pass Faraday mirror 48 of Embodiment 1, and can further improve position reproducibility and the like compared to Embodiment 1.

[0115] 4. Implementation Method 2

[0116] 4.1 Structure

[0117] Figure 9 The structure of the laser system 10B according to the second embodiment is schematically shown. Figure 4 The laser system 10A shown is different from the laser system 10B. The laser system 10B includes a laser oscillator system 32 instead of Figure 4 The laser oscillator system 30 shown. The laser oscillator system 32 includes a third laser oscillator LO3 and a Faraday rotator 90 instead of Figure 4 The second laser oscillator LO2 is shown. In addition, the symbol "laser oscillator 3" in the figure represents the third laser oscillator LO3.

[0118] The third laser oscillator LO3 outputs second pulsed laser light PL2 with a first polarization direction at an ultraviolet wavelength of 150 nm to 380 nm. The third laser oscillator LO3 can be a KrF excimer laser or an ArF excimer laser. Furthermore, the spectral linewidth of the second pulsed laser light PL2 output from the third laser oscillator LO3 can be narrowed to less than 1 pm.

[0119] The Faraday rotator 90 is composed of a Faraday material 94 that rotates the polarization direction of the second pulsed laser PL2 45 degrees counterclockwise when observing the direction in which the second pulsed laser PL2 travels, and a permanent magnet 96. The Faraday material 94 can be, for example, CaF2, MgF2, or synthetic quartz. Instead of the Faraday rotator 90, a wavelength plate that rotates the polarization direction of the second pulsed laser PL2 45 degrees counterclockwise can also be used. Other structures are similar to Figure 4 The structures shown are the same.

[0120] The Faraday rotator 90 is an example of a “second Faraday rotator” in the present disclosure. The Faraday material 94 is an example of a “third Faraday material” in the present disclosure. The permanent magnet 96 is an example of a “second permanent magnet” in the present disclosure.

[0121] 4.2 Action

[0122] The laser processor 222 causes the first pulse laser PL1 and the second pulse laser PL2 to be alternately output at the same repetition frequency. Figure 10 FIG. 2 shows the propagation of the second pulsed laser light PL2 output from the third laser oscillator LO3.

[0123] The second pulsed laser light PL2 output from the third laser oscillator LO3 passes through Faraday rotator 90. At this point, the polarization direction of the second pulsed laser light PL2 is rotated 45 degrees counterclockwise to the second polarization direction. The second pulsed laser light PL2 that has passed through Faraday rotator 90 is reflected by the second polarizer 46 and enters the multi-pass Faraday mirror 48. The subsequent propagation is the same as in Embodiment 1.

[0124] Furthermore, the propagation of the first pulsed laser PL1 outputted from the first laser oscillator LO1 is the same as that in the first embodiment, and the control of the current flowing through the electromagnet via the power supply 50 and other operations are also the same as those in the first embodiment.

[0125] 4.3 Effect

[0126] The laser system 10B of the second embodiment can achieve the same effects as those of the first embodiment. In the laser system 10B, the polarization directions of the first pulsed laser light PL1 outputted from the first laser oscillator LO1 and the second pulsed laser light PL2 outputted from the third laser oscillator LO3 can be made the same.

[0127] 5. Implementation Method 3

[0128] 5.1 Structure

[0129] Figure 11 The structure of the laser system 10C according to the third embodiment is shown. Figure 4 The laser system 10C is different from the laser system 10A shown in FIG. 10C includes a laser oscillator system 33 instead of Figure 4 The laser oscillator system 30 is shown. The laser oscillator system 33 includes a fourth laser oscillator LO4, a beam splitter BS, a first amplifier 130, a second amplifier 132, and a Faraday rotator 140. The reference "Laser Oscillator 4" in the figure indicates the fourth laser oscillator LO4. The references "Amplifier 1" and "Amplifier 2" in the figure indicate the first amplifier 130 and the second amplifier 132.

[0130] The fourth laser oscillator LO4 outputs seed light SL in a first polarization direction at an ultraviolet wavelength of 150 nm to 380 nm. The fourth laser oscillator LO4 may also be a solid-state laser capable of outputting seed light SL at a wavelength of a KrF laser or an ArF laser with high repetition rate. In addition, the spectral line width of the seed light SL output from the fourth laser oscillator LO4 may also be narrowbanded to less than 1 pm. For example, the solid-state laser may be a triple wave (wavelength 248.4 nm) of a Ti sapphire laser with a wavelength of 745.2 nm or a quadruple wave (wavelength 193.4 nm) of a Ti sapphire laser with a wavelength of 773.6 nm.

[0131] The beam splitter BS splits the seed light SL output from the fourth laser oscillator LO4 into two seed lights SL. The division ratio of the transmitted light amount to the reflected light amount in the beam splitter BS can be 1:1.

[0132] The first amplifier 130 and the second amplifier 132 each amplify the seed light SL split by the beam splitter BS. For example, the first amplifier 130 and the second amplifier 132 are discharge-exciter amplifiers, which may include Fabry-Perot resonators, ring resonators, or multi-pass amplifiers. A multi-pass amplifier uses multiple mirrors to fold back the beam after passing through the amplifier, allowing the beam to pass through the same amplifier multiple times.

[0133] The repetition frequencies of the first amplifier 130 and the second amplifier 132 are the same, and the repetition frequency of the fourth laser oscillator LO4 is twice the repetition frequency of the first amplifier 130 and the second amplifier 132. For example, the repetition frequency of each of the first amplifier 130 and the second amplifier 132 is 6 kHz, and the repetition frequency of the fourth laser oscillator LO4 is 12 kHz.

[0134] The Faraday rotator 140 is composed of a Faraday material 144 and a permanent magnet 146 that rotate the polarization direction of the pulsed laser light PL by 45 degrees counterclockwise when observing the direction in which the pulsed laser light PL travels. The Faraday material 144 can be, for example, CaF2, MgF2, or synthetic quartz. A wavelength plate that rotates the polarization direction of the pulsed laser light PL by 45 degrees counterclockwise can also be used instead of the Faraday rotator 140. Other structures are similar to Figure 4 same.

[0135] The Faraday rotator 140 is an example of a “third Faraday rotator” in the present disclosure. The Faraday material 144 is an example of a “fourth Faraday material” in the present disclosure. The permanent magnet 146 is an example of a “third permanent magnet” in the present disclosure.

[0136] 5.2 Action

[0137] The seed light SL in the first polarization direction outputted from the fourth laser oscillator LO4 transmits 50% of the seed light through the beam splitter BS and enters the first amplifier 130 , while the remaining 50% of the seed light is reflected and enters the second amplifier 132 .

[0138] The laser processor 222 alternately operates the first amplifier 130 and the second amplifier 132 for each pulse of the seed light SL. When the first amplifier 130 operates, it amplifies one of the seed light SL split by the beam splitter BS and outputs the first pulsed laser light PL1.

[0139] When the second amplifier 132 operates, the second amplifier 132 amplifies the other seed light SL split by the beam splitter BS and outputs the second pulsed laser light PL2 .

[0140] Figure 12 FIG. 10 shows the propagation of the first pulsed laser light PL1 output from the first amplifier 130. The propagation of the first pulsed laser light PL1 output from the first amplifier 130 is the same as that in the first embodiment.

[0141] Figure 13 FIG4 shows the propagation of the second pulsed laser light PL2 output from the second amplifier 132. The propagation of the second pulsed laser light PL2 output from the second amplifier 132 is the same as that in Embodiment 2. The laser processor 222 turns off the electromagnet when the first pulsed laser light PL1 is incident on the multi-pass Faraday mirror 48, and turns on the electromagnet when the second pulsed laser light PL2 is incident on the multi-pass Faraday mirror 48.

[0142] As a result, the first pulsed laser PL1 of the first polarization direction and the second pulsed laser PL2 of the second polarization direction are combined in the beam combiner 40 and propagate in a common direction. The combined first pulsed laser PL1 and second pulsed laser PL2 of the fourth polarization direction are alternately output from the laser system 10C.

[0143] 5.3 Effect

[0144] The laser system 10C of the third embodiment can achieve the same effects as those of the first embodiment. In the laser system 10C, since only one fourth laser oscillator LO4 is provided, fluctuations in the wavelength and line width of the pulsed laser light output from the laser system 10C can be reduced.

[0145] 6. Regarding the manufacturing method of electronic devices

[0146] Figure 14The structure of exposure apparatus 800 is schematically shown. Exposure apparatus 800 includes an illumination optical system 806 and a projection optical system 808. Laser system 10A generates laser light and outputs it to exposure apparatus 800. Illumination optical system 806 illuminates the reticle pattern of a (not shown) reticle positioned on reticle stage RT with the laser light incident from laser system 10A. Projection optical system 808 reduces and projects the laser light transmitted through the reticle, forming an image on a (not shown) workpiece positioned on workpiece stage WT. The workpiece is a photosensitive substrate such as a semiconductor wafer coated with photoresist.

[0147] The exposure device 800 synchronizes and moves the reticle stage RT and the workpiece table WT in parallel, exposing the workpiece to laser light reflecting the reticle pattern. After the reticle pattern is transferred to a semiconductor wafer through the exposure process, semiconductor devices can be manufactured through multiple steps. Semiconductor devices are an example of "electronic devices" in this disclosure. The system is not limited to the laser system 10A; laser systems 10B, 10C, and the like can also be used.

[0148] 7. Others

[0149] The above description is not limiting but merely illustrative. Therefore, it is obvious to those skilled in the art that the embodiments of the present disclosure can be modified without departing from the scope of the claims. In addition, it is also obvious to those skilled in the art that the embodiments of the present disclosure can be used in combination.

[0150] Unless expressly stated otherwise, the terms used in this specification and claims should be interpreted as “non-restrictive” terms. For example, terms such as “including”, “having”, “having”, and “having” should be interpreted as “not excluding the presence of constituent elements other than the recorded constituent elements”. In addition, the modifier “one” should be interpreted as meaning “at least one” or “one or more”. In addition, the term “at least one of A, B, and C” should be interpreted as “A”, “B”, “C”, “A+B”, “A+C”, “B+C”, or “A+B+C”. Furthermore, it should be interpreted as also including combinations of these with parts other than “A”, “B”, and “C”.

Claims

1. A laser system comprising: A laser oscillator system that outputs a first pulsed laser light in a first polarization direction and a second pulsed laser light in a second polarization direction rotated 45 degrees in a first rotation direction relative to the first polarization direction; a beam combiner that combines the first pulsed laser light and the second pulsed laser light so that the first pulsed laser light and the second pulsed laser light propagate in a common direction, the beam combiner comprising: a first polarizer that transmits the first pulsed laser light; a first Faraday rotator that rotates the polarization direction of the first pulsed laser light after passing through the first polarizer by 45 degrees in a second rotation direction opposite to the first rotation direction; and a second polarizer that transmits the first pulsed laser light after passing through the first Faraday rotator and reflects the second pulsed laser light; and a multi-pass Faraday mirror, which reflects the first pulsed laser light after passing through the second polarizer and the second pulsed laser light after being reflected by the second polarizer toward the second polarizer, the multi-pass Faraday mirror comprising: a first Faraday material, through which the first pulsed laser light and the second pulsed laser light pass; an electromagnet, which applies a magnetic field to the first Faraday material; and a plurality of reflecting mirrors, which return the first pulsed laser light and the second pulsed laser light after passing through the first Faraday material to the first Faraday material; a power source that causes current to flow through the electromagnet; and A processor controls the current flowing through the electromagnet via the power supply so that when the first pulsed laser passes through the first Faraday material, the current does not flow through the electromagnet, and when the second pulsed laser passes through the first Faraday material, the current flows through the electromagnet so as to rotate the polarization direction of the second pulsed laser by 90 degrees.

2. The laser system according to claim 1, wherein: The processor alternately outputs the first pulse laser and the second pulse laser from the laser oscillator system.

3. The laser system according to claim 1, wherein: The first Faraday material is calcium fluoride, magnesium fluoride or synthetic quartz.

4. The laser system according to claim 1, wherein: The first Faraday rotator includes a second Faraday material and a first permanent magnet applying a magnetic field to the second Faraday material. The second Faraday material is calcium fluoride, magnesium fluoride or synthetic quartz.

5. The laser system according to claim 1, wherein: The multi-pass Faraday mirror includes four high-reflection mirrors as the multiple reflectors, and the four high-reflection mirrors reflect the first pulse laser and the second pulse laser after passing through the first Faraday material, so that the incident first pulse laser and the second pulse laser are emitted toward the second polarizer after passing through the first Faraday material eight times.

6. The laser system according to claim 1, wherein: The first Faraday material includes a portion of each of the surface for incident first pulse laser and second pulse laser and the surface for output of the first pulse laser and the second pulse laser in the first Faraday material, including a reflective coating of the multiple reflectors for reflecting the first pulse laser and the second pulse laser, so that the incident first pulse laser and the second pulse laser pass through the first Faraday material multiple times and are output toward the second polarizer.

7. The laser system of claim 1 , wherein: The laser oscillator system comprises: a first laser oscillator that outputs the first pulsed laser light in the first polarization direction; and A second laser oscillator outputs the second pulse laser light of the second polarization direction.

8. The laser system of claim 1, wherein: The laser oscillator system comprises: a first laser oscillator, which outputs the first pulse laser light in the first polarization direction; a third laser oscillator, which outputs the second pulsed laser light in the first polarization direction; as well as a second Faraday rotator that rotates the polarization direction of the first pulsed laser light output from the third laser oscillator by 45 degrees toward the first rotation direction; The second pulsed laser light in the second polarization direction is output from the second Faraday rotator.

9. The laser system according to claim 8, wherein: The second Faraday rotator includes a third Faraday material and a second permanent magnet applying a magnetic field to the third Faraday material. The third Faraday material is calcium fluoride, magnesium fluoride or synthetic quartz.

10. The laser system of claim 1, wherein: The laser oscillator system comprises: a fourth laser oscillator, which outputs seed light in the first polarization direction; a beam splitter that splits the seed light; a first amplifier configured to amplify one of the seed lights separated by the beam splitter and output the first pulsed laser light; a second amplifier that amplifies the other seed light separated by the beam splitter and outputs the second pulse laser light; as well as a third Faraday rotator configured to rotate the polarization direction of the second pulsed laser light output from the second amplifier by 45 degrees toward the first rotation direction.

11. The laser system of claim 10, wherein: The third Faraday rotator includes a fourth Faraday material and a third permanent magnet applying a magnetic field to the fourth Faraday material. The fourth Faraday material is calcium fluoride, magnesium fluoride or synthetic quartz.

12. The laser system of claim 10, wherein: The fourth laser oscillator is a solid-state laser that outputs the seed light having a wavelength of KrF excimer laser light or ArF excimer laser light.

13. The laser system of claim 10, wherein: The first amplifier and the second amplifier each include a Fabry-Perot resonator, a ring resonator, or a multi-pass amplifier.

14. The laser system of claim 10, wherein: The processor operates the first amplifier and the second amplifier alternately for each pulse of the seed light output from the fourth laser oscillator.

15. The laser system of claim 1, wherein: The wavelengths of the first pulse laser and the second pulse laser are ultraviolet wavelengths.

16. The laser system of claim 1, wherein: The first pulse laser and the second pulse laser output by the beam combiner have the same polarization direction.

17. A method for manufacturing an electronic device, comprising the following steps: The laser is generated by the laser system, Outputting the laser to an exposure device, exposing the laser light on a photosensitive substrate in the exposure device to manufacture an electronic device, The laser system has: A laser oscillator system that outputs a first pulsed laser light in a first polarization direction and a second pulsed laser light in a second polarization direction rotated 45 degrees in a first rotation direction relative to the first polarization direction; a beam combiner that combines the first pulsed laser light and the second pulsed laser light so that the first pulsed laser light and the second pulsed laser light propagate in a common direction, the beam combiner comprising: a first polarizer that transmits the first pulsed laser light; a first Faraday rotator that rotates the polarization direction of the first pulsed laser light after passing through the first polarizer by 45 degrees in a second rotation direction opposite to the first rotation direction; and a second polarizer that transmits the first pulsed laser light after passing through the first Faraday rotator and reflects the second pulsed laser light; and a multi-pass Faraday mirror, which reflects the first pulsed laser light after passing through the second polarizer and the second pulsed laser light after being reflected by the second polarizer toward the second polarizer, the multi-pass Faraday mirror comprising: a first Faraday material, through which the first pulsed laser light and the second pulsed laser light pass; an electromagnet, which applies a magnetic field to the first Faraday material; and a plurality of reflecting mirrors, which return the first pulsed laser light and the second pulsed laser light after passing through the first Faraday material to the first Faraday material; a power source that causes current to flow through the electromagnet; and A processor controls the current flowing through the electromagnet via the power supply so that when the first pulsed laser passes through the first Faraday material, the current does not flow through the electromagnet, and when the second pulsed laser passes through the first Faraday material, the current flows through the electromagnet so as to rotate the polarization direction of the second pulsed laser by 90 degrees.

Images