Laser system, method for adjusting a laser system, and method for manufacturing an electronic device

Abstract

This provides a laser system that readjusts the output timing of the oscillation trigger signal. [Solution] The laser system includes a processor that determines the timing difference from when a first switch having a first delay characteristic, included in a first pulse compression circuit, is turned on until a second switch having a second delay characteristic, is turned on, so that the oscillation stage laser device and the amplification stage laser device are synchronized, and controls the output timing of the first oscillation trigger signal input to the first pulse compression circuit and the second oscillation trigger signal input to the second pulse compression circuit, and further includes a processor that corrects the output timing of at least one of the first oscillation trigger signal and the second oscillation trigger signal so that changes in the timing difference are suppressed when either the first switch or the second switch is replaced with a third switch having a third delay characteristic.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a laser system, an adjustment method for the laser system, and a method for manufacturing an electronic device.

BACKGROUND ART

[0002] In recent years, in semiconductor exposure apparatuses, as semiconductor integrated circuits have become finer and more highly integrated, improvement in resolution has been demanded. For this reason, the wavelength of light emitted from an exposure light source has been shortened. For example, as a gas laser apparatus for exposure, a KrF excimer laser apparatus that outputs laser light with a wavelength of about 248 nm, and an ArF excimer laser apparatus that outputs laser light with a wavelength of about 193 nm are used.

[0003] The spectral line width of the spontaneous oscillation light of the KrF excimer laser apparatus and the ArF excimer laser apparatus is as wide as 350 to 400 pm. Therefore, if a projection lens is configured with a material that transmits ultraviolet light such as KrF and ArF laser light, chromatic aberration may occur. As a result, the resolution may decrease. Accordingly, it is necessary to narrow the spectral line width of the laser light output from the gas laser apparatus to a level at which chromatic aberration can be ignored. Therefore, a line narrowing module (Line Narrowing Module: LNM) including a line narrowing element (such as an etalon or a grating) for narrowing the spectral line width may be provided in the laser resonator of the gas laser apparatus. A gas laser apparatus in which the spectral line width is narrowed is referred to as a line-narrowed gas laser apparatus.

PRIOR ART DOCUMENTS

PATENT DOCUMENTS

[0004]

PATENT DOCUMENT 1

PATENT DOCUMENT 2

[0005] A laser system relating to one aspect of the present disclosure includes: an oscillation stage laser device including a first pulse compression circuit; an amplification stage laser device including a second pulse compression circuit; and a processor that determines the timing difference from the time a first switch having a first delay characteristic included in the first pulse compression circuit is turned on until a second switch having a second delay characteristic included in the second pulse compression circuit is turned on, so that the oscillation stage laser device and the amplification stage laser device are synchronized, and controls the output timing of a first oscillation trigger signal input to the first pulse compression circuit and a second oscillation trigger signal input to the second pulse compression circuit, wherein if either the first switch or the second switch is replaced with a third switch having a third delay characteristic, the processor corrects the output timing of at least one of the first oscillation trigger signal and the second oscillation trigger signal so that a change in the timing difference is suppressed.

[0006] A method for adjusting a laser system according to one aspect of the present disclosure comprises an oscillation stage laser device including a first pulse compression circuit and an amplification stage laser device including a second pulse compression circuit, wherein the method determines a timing difference from the time a first switch having a first delay characteristic included in the first pulse compression circuit is turned on until a second switch having a second delay characteristic included in the second pulse compression circuit is turned on, so that the oscillation stage laser device and the amplification stage laser device are synchronized, and corrects the output timing of at least one of a first oscillation trigger signal input to the first pulse compression circuit and a second oscillation trigger signal input to the second pulse compression circuit so that changes in the timing difference are suppressed when either the first switch or the second switch is replaced with a third switch having a third delay characteristic.

[0007] A method for manufacturing an electronic device according to one aspect of the present disclosure includes generating pulsed laser light with a laser system comprising: an oscillation stage laser device including a first pulse compression circuit; an amplification stage laser device including a second pulse compression circuit; and a processor that determines the timing difference from when a first switch having a first delay characteristic included in the first pulse compression circuit is turned on until a second switch having a second delay characteristic included in the second pulse compression circuit is turned on, so that the oscillation stage laser device and the amplification stage laser device are synchronized, and controls the output timing of a first oscillation trigger signal input to the first pulse compression circuit and a second oscillation trigger signal input to the second pulse compression circuit, the processor corrects the output timing of at least one of the first oscillation trigger signal and the second oscillation trigger signal so that a change in the timing difference is suppressed when either the first switch or the second switch is replaced with a third switch having a third delay characteristic; outputting the pulsed laser light to an exposure apparatus; and exposing a photosensitive substrate with the pulsed laser light in the exposure apparatus in order to manufacture an electronic device. [Brief explanation of the drawing]

[0008] Some embodiments of this disclosure are described below, merely as examples, with reference to the accompanying drawings. [Figure 1] Figure 1 shows the configuration of the exposure system in the comparative example. [Figure 2] Figure 2 shows the configuration of the laser system shown in Figure 1. [Figure 3] Figure 3 shows the configuration of a power supply unit including the charger and pulse power module shown in Figure 2. [Figure 4] Figure 4 is a time chart showing the oscillation trigger signal and the turn-on timing of switches SW1 and SW2 in the comparative example. [Figure 5] Figure 5 shows the delay time characteristics of switches SW1 and SW2. [Figure 6]Figure 6 is a time chart showing the case where switch SW2 in the comparative example is replaced with switch SW3, which has different delay time characteristics than switch SW1. [Figure 7] Figure 7 is a flowchart showing the procedure for synchronous control of the laser system in the embodiment. [Figure 8] Figure 8 shows a portion of the delay time characteristics of switch SW3 superimposed on the delay time characteristics of switches SW1 and SW2. [Figure 9] Figure 9 shows an example of the difference data created in S7 of Figure 7. [Figure 10] Figure 10 is a flowchart showing the procedure for correcting the output timing of the oscillation trigger signal in the embodiment. Embodiment

[0009] <Contents> 1. Comparative Example 1.1 Exposure System 1.2 Exposure apparatus 200 1.3 Laser System 100 1.3.1 Configuration 1.3.2 Operation 1.4 Power supply 1.4.1 Configuration 1.4.2 Operation 2. Issues with the Comparative Example 3. Laser system 100 that readjusts the output timing of the oscillation trigger signal. 3.1 Overview 3.2 Operation 3.3 Effect 4. Others 4.1 Processor 4.2 Supplement

[0010] The embodiments of this disclosure will be described in detail below with reference to the drawings. The embodiments described below are examples of this disclosure and do not limit the content of this disclosure. Furthermore, not all of the configurations and operations described in the embodiments are necessarily essential for the configurations and operations of this disclosure. The same reference numerals are used for identical components, and redundant descriptions are omitted.

[0011] 1. Comparative Example 1.1 Exposure System Figure 1 shows the configuration of the exposure system in the comparative example. The comparative example of the present disclosure is an embodiment that the applicant recognizes as being known only to the applicant, and is not a known example that the applicant admits to be publicly known.

[0012] The exposure system includes a laser system 100 and an exposure apparatus 200. In Figure 1, the laser system 100 is illustrated in a simplified manner. The laser system 100 includes a laser control processor 130, and is configured to output pulsed laser light LB toward the exposure apparatus 200.

[0013] 1.2 Exposure Apparatus 200 As shown in Figure 1, the exposure apparatus 200 includes an illumination optical system 201, a projection optical system 202, and an exposure control processor 230. The exposure control processor 230 transmits an oscillation command Tr0 to the laser control processor 130, and also controls the entire exposure apparatus 200. The illumination optical system 201 illuminates the reticle pattern of a reticle (not shown) arranged on a reticle stage RT with the pulsed laser light LB incident from the laser system 100. The projection optical system 202 reduces and projects the pulsed laser light LB that has passed through the reticle, and forms an image on a workpiece (not shown) arranged on a workpiece table WT. The workpiece is a photosensitive substrate such as a semiconductor wafer coated with photoresist.

[0014] The exposure control processor 230 causes the reticle stage RT and the workpiece table WT to translate in synchronization, whereby the exposure apparatus 200 exposes the workpiece with the pulsed laser light LB that reflects the reticle pattern. After the reticle pattern is transferred to the semiconductor wafer through the exposure process as described above, an electronic device can be manufactured through a plurality of processes.

[0015] 1.3 Laser System 100 1.3.1 Configuration Figure 2 shows the configuration of the laser system 100 shown in Figure 1. The laser system 100 includes an oscillation stage laser device 110, an amplification stage laser device 120, a laser control processor 130, a synchronization processor 135, and monitor modules 140 and 150. The oscillation stage laser device 110 includes a laser chamber 10, a charger 12, a pulse power module 13, a narrowband module 14, and an output mirror 15. The pulse power module 13 corresponds to the first pulse compression circuit in this disclosure. The output mirror 15 and the grating 14c included in the narrowband module 14 constitute an optical resonator.

[0016] The laser chamber 10 includes windows 10a and 10b, which are positioned in the optical path of the optical resonator. The laser chamber 10 is configured to contain a laser gas containing components of the laser gain medium and includes a pair of electrodes 11a and 11b for applying a voltage to the laser gain medium. The laser gain medium is, for example, ArF, KrF, etc.

[0017] The direction of propagation of the pulsed laser beam LB1 output from the output mirror 15 is defined as the Z direction. The direction in which electrodes 11a and 11b face each other is defined as the V direction or -V direction. The Z direction and the V direction are perpendicular to each other, and the direction perpendicular to both of these is defined as the H direction or -H direction. Figure 2 shows the configuration of the laser system 100 as seen in the -H direction.

[0018] The pulse power module 13 includes a main capacitor C0 and a switch SW1, which will be described later with reference to Figure 3. Switch SW1 corresponds to the first switch in this disclosure and is a solid switch such as an IGBT (insulated gate bipolar transistor) switch, a BJT (bipolar junction transistor) switch, or a thyristor switch. The main capacitor C0 is connected to the charger 12, and switch SW1 is connected to the synchronous processor 135. The output terminals of the pulse power module 13 are connected to electrodes 11a and 11b.

[0019] The narrowband module 14 includes a prism 14b and a grating 14c. The prism 14b is positioned in the optical path of light emitted from the window 10a. The prism 14b is rotatable about an axis parallel to the V direction by a rotating stage (not shown). The grating 14c is positioned in the optical path of light transmitted through the prism 14b. The output mirror 15 is composed of a partial reflection mirror.

[0020] The monitor module 140 includes a beam splitter 41 and an optical sensor 42. The beam splitter 41 is positioned in the optical path of the pulsed laser light LB1 output from the output mirror 15 and is configured to transmit a portion of the pulsed laser light LB1 with high transmittance and reflect the other portion. The optical sensor 42 is positioned in the optical path of the pulsed laser light LB1 reflected by the beam splitter 41.

[0021] The amplified laser device 120 includes a laser chamber 20, a charger 22, a pulse power module 23, a rear mirror 24, and an output mirror 25. The pulse power module 23 corresponds to a second pulse compression circuit in this disclosure. The rear mirror 24 and the output mirror 25 constitute an optical resonator. The rear mirror 24 is a partially reflective mirror with a higher reflectivity than the output mirror 25 and is positioned in the optical path of the pulsed laser beam LB1. The configurations of the laser chamber 20, charger 22, pulse power module 23, and output mirror 25 are the same as those of the laser chamber 10, charger 12, pulse power module 13, and output mirror 15, respectively. The configurations of the windows 20a and 20b and the pair of electrodes 21a and 21b included in the laser chamber 20 are the same as those of windows 10a and 10b and electrodes 11a and 11b, respectively.

[0022] The monitor module 150 is positioned in the optical path of the pulsed laser light LB2 output from the output mirror 25. The configurations of the beam splitter 51 and optical sensor 52 included in the monitor module 150 are the same as those of the beam splitter 41 and optical sensor 42, respectively.

[0023] 1.3.2 Operation The laser control processor 130 receives an oscillation command Tr0 from the exposure control processor 230. Based on the oscillation command Tr0, the laser control processor 130 transmits a trigger signal Tr1 to the synchronization processor 135. Based on the trigger signal Tr1, the synchronization processor 135 transmits charge start signals Tr111 and Tr121 to the chargers 12 and 22, respectively, and then transmits oscillation trigger signals Tr112 and Tr122 to the pulse power modules 13 and 23, respectively. The oscillation trigger signals Tr112 and Tr122 correspond to the first and second oscillation trigger signals in this disclosure, respectively.

[0024] In the oscillating stage laser device 110, the charger 12 starts charging the main capacitor C0 when it receives a charging start signal Tr111 from the synchronous processor 135. The switch SW1 included in the pulse power module 13 turns on when it receives an oscillation trigger signal Tr112 from the synchronous processor 135. When the switch SW1 is turned on, the pulse power module 13 generates a pulsed high voltage from the electrical energy charged in the main capacitor C0 and applies this high voltage between electrodes 11a and 11b.

[0025] When a high voltage is applied between electrodes 11a and 11b, a discharge occurs between them. The energy of this discharge excites the laser gas inside the laser chamber 10, causing it to shift to a higher energy level. When the excited laser gas then shifts to a lower energy level, it emits light with a wavelength corresponding to the energy level difference.

[0026] Light generated inside the laser chamber 10 is emitted outside the laser chamber 10 through windows 10a and 10b. The light emitted from window 10a has its beam width expanded in a plane parallel to the HZ plane by prism 14b. The light that passes through prism 14b is incident on grating 14c.

[0027] Light incident on the grating 14c is reflected by multiple grooves in the grating 14c and diffracted in a direction corresponding to the wavelength of the light. By matching the incident angle of the light incident on the grating 14c with the diffraction angle of the diffracted light of the desired wavelength, the wavelength of the diffracted light returned from the grating 14c to the prism 14b is selected. As the orientation of the prism 14b changes due to the rotation angle of the rotating stage, the incident angle of the light incident on the grating 14c changes, and the wavelength selected by the narrowband module 14 changes. The prism 14b reduces the beam width of the diffracted light returned from the grating 14c in the HZ plane and returns that light to the inside of the laser chamber 10 through the window 10a.

[0028] The output mirror 15 transmits a portion of the light emitted from the window 10b and outputs it, while reflecting the other portion back into the laser chamber 10.

[0029] In this way, the light emitted from the laser chamber 10 travels back and forth between the narrowband module 14 and the output mirror 15. This light is amplified each time it passes through the discharge space between electrodes 11a and 11b, and narrowed each time it is folded back by the narrowband module 14. The resulting laser-oscillating and narrowed-band light is output from the output mirror 15 as pulsed laser light LB1.

[0030] The monitor module 140 transmits a signal indicating the emission timing of the pulsed laser beam LB1 to the laser control processor 130. The emission timing of the pulsed laser beam LB1 roughly corresponds to the timing when the switch SW1 included in the pulsed power module 13 turns on. The monitor module 140 also measures the pulse energy and beam profile of the pulsed laser beam LB1.

[0031] The pulsed laser beam LB1 output from the oscillation stage laser device 110 enters the laser chamber 20 via the rear mirror 24 and window 20a. The timing of the input of the oscillation trigger signal Tr122 to the switch SW2 (see Figure 3) of the pulse power module 23 is controlled so that a discharge begins between electrodes 21a and 21b at the same time that the pulsed laser beam LB1 enters the laser chamber 20. Switch SW2 corresponds to the second switch in this disclosure. The pulsed laser beam LB1 travels back and forth between the rear mirror 24 and the output mirror 25. This light is amplified each time it passes through the discharge space between electrodes 21a and 21b and is output from the output mirror 25 as pulsed laser beam LB2.

[0032] The amplification stage laser device 120 amplifies the pulse energy while maintaining the spectrum of the pulsed laser light LB1, which has been narrowed in bandwidth by the oscillation stage laser device 110. This enables the laser system 100 to achieve both narrow bandwidth and high output.

[0033] The monitor module 150 transmits a signal indicating the emission timing of the pulsed laser beam LB2 to the laser control processor 130. The emission timing of the pulsed laser beam LB2 roughly corresponds to the timing when the switch SW2 included in the pulsed power module 23 turns on. The monitor module 150 also measures the pulse energy and beam profile of the pulsed laser beam LB2.

[0034] The pulsed laser light LB that has passed through the monitor module 150 is then incident on the exposure apparatus 200.

[0035] 1.4 Power supply 1.4.1 Configuration Figure 3 shows the configuration of a power supply unit including the chargers 12 and 22 and pulse power modules 13 and 23 shown in Figure 2. Charger 12 includes a DC variable power supply E. In addition to the main capacitor C0 and switch SW1, pulse power module 13 includes a step-up transformer TC, magnetic switches SR0, SR1, and SR2, and first and second transfer capacitors C1 and C2. The output terminals of pulse power module 13 are connected to peaking capacitor Cp and electrodes 11a and 11b, which are connected in parallel to each other. Peaking capacitor Cp and electrodes 11a and 11b are contained within the laser chamber 10.

[0036] Magnetic switches SR0 to SR2 all contain saturable reactors. Each of the magnetic switches SR0 to SR2 is configured to switch to low impedance when the time integral of the voltage applied across its terminals reaches a predetermined value determined by the characteristics of each magnetic switch.

[0037] One terminal of the main capacitor C0 is connected to the DC variable power supply E and one terminal of the magnetic switch SR0, respectively. The other terminal of the main capacitor C0 is connected to the reference potential. The other terminal of the magnetic switch SR0 is connected to the reference potential via the primary winding of the step-up transformer TC, which is connected in series with the switch SW1.

[0038] One terminal of the magnetic switch SR1 is connected to a reference potential via the secondary winding of the step-up transformer TC, and is also connected to one terminal of the first transfer capacitor C1. The other terminal of the first transfer capacitor C1 is connected to the reference potential. In other words, the secondary winding of the step-up transformer TC and the first transfer capacitor C1 are connected in parallel to each other. The first transfer capacitor C1 and the magnetic switch SR1 constitute the first magnetic pulse compression circuit PC1.

[0039] The other terminal of magnetic switch SR1 is connected to one terminal of magnetic switch SR2, and also to one terminal of the second transfer capacitor C2. The other terminal of the second transfer capacitor C2 is connected to a reference potential. The second transfer capacitor C2 and magnetic switch SR2 constitute the second magnetic pulse compression circuit PC2.

[0040] The other terminal of the magnetic switch SR2 is connected to one terminal of the peaking capacitor Cp and electrode 11a. The other terminal of the peaking capacitor Cp and electrode 11b are connected to a reference potential.

[0041] 1.4.2 Operation When the charger 12 receives a charging start signal Tr111 from the synchronous processor 135, the main capacitor C0 is charged by the DC variable power supply E. When the switch SW1 receives an oscillation trigger signal Tr112 from the synchronous processor 135 and turns on, the voltage across the main capacitor C0 is applied to the magnetic switch SR0. When the time integral value of the voltage applied to the magnetic switch SR0 reaches a predetermined value, the magnetic switch SR0 turns on, and a pulsed current flows from the main capacitor C0 to the magnetic switch SR0, the primary winding of the step-up transformer TC, and the switch SW1.

[0042] When current flows through the primary winding of the step-up transformer TC, electromagnetic induction causes a current to flow through the secondary winding of the step-up transformer TC, corresponding to the winding ratio of the step-up transformer TC. When current flows through the secondary winding of the step-up transformer TC, the first transfer capacitor C1 is charged, and the voltage across the first transfer capacitor C1 is applied to the magnetic switch SR1. When the time integral value of the voltage applied to the magnetic switch SR1 reaches a predetermined value, the magnetic switch SR1 turns on, and a pulsed current flows through the magnetic switch SR1.

[0043] When current flows through magnetic switch SR1, the charge from the first transfer capacitor C1 is transferred to the second transfer capacitor C2, charging the second transfer capacitor C2, and the voltage across the second transfer capacitor C2 is applied to magnetic switch SR2. The pulse width of the current used to charge the second transfer capacitor C2 is shorter than the pulse width of the current used to charge the first transfer capacitor C1, resulting in a higher voltage. When the time integral value of the voltage applied to magnetic switch SR2 reaches a predetermined value, magnetic switch SR2 turns on, and a pulsed current flows through magnetic switch SR2.

[0044] When current flows through the magnetic switch SR2, the charge from the second transfer capacitor C2 is transferred to the peaking capacitor Cp, which is then charged. The pulse width of the current used to charge the peaking capacitor Cp is shorter than the pulse width of the current used to charge the second transfer capacitor C2, resulting in a higher voltage.

[0045] When the voltage across the peaking capacitor Cp reaches the breakdown voltage of the laser gas, a discharge occurs between electrodes 11a and 11b. This excites the laser gas, causing the laser to oscillate. Switch SW1 switches at a predetermined repetition frequency, and a pulsed laser beam LB1 is output at that repetition frequency.

[0046] The configuration and operation of the charger 22 and pulse power module 23 are the same as those of the charger 12 and pulse power module 13. However, the switch included in the pulse power module 23 is designated as SW2.

[0047] Figure 4 is a time chart showing the oscillation trigger signals Tr112 and Tr122 and the turn-on timing of switches SW1 and SW2 in a comparative example. Each vertical dashed line in Figure 4 indicates that the timing of the events connected by that dashed line is the same. After receiving the trigger signal Tr1, the synchronous processor 135 outputs the charge start signals Tr111 and Tr121, which are not shown in Figure 4, and then outputs the oscillation trigger signals Tr112 and Tr122. The output timing of the oscillation trigger signals Tr112 and Tr122 is determined by adding the correction times Δt0112 and Δt0122, respectively, to the reference time ST. The reference time ST is set as the time when sufficient time has elapsed for chargers 12 and 22, which have received the charge start signals Tr111 and Tr121, to charge the corresponding main capacitor C0. The synchronization processor 135 controls the output timing of the oscillation trigger signals Tr112 and Tr122 so that the synchronization between the oscillation stage laser device 110 and the amplification stage laser device 120 is optimized.

[0048] Before the laser system 100 is put into full operation, adjustment oscillation is performed. Adjustment oscillation is a process in which laser oscillation is performed while changing the time difference between correction times Δt0112 and Δt0122, and the time difference at which the measurement results of the pulse energy and beam profile of the pulsed laser beams LB1 and LB2 are in an optimal state is determined as the synchronization time difference Δt0.

[0049] The synchronization time difference Δt0 is an important control parameter for optimizing the relationship between the timing of the pulsed laser beam LB1 entering the laser chamber 20 and the timing of the start of discharge between electrodes 21a and 21b. More directly defining this relationship is the turn-on timing difference Δs0 of switches SW1 and SW2. If the delay time DS1 from when switch SW1 receives the oscillation trigger signal Tr112 until it turns on, and the delay time DS2 from when switch SW2 receives the oscillation trigger signal Tr122 until it turns on, are always the same, then the timing difference Δs0 will always be the same as the synchronization time difference Δt0. If the timing difference Δs0 is always the same as the synchronization time difference Δt0, then the oscillation stage laser device 110 and the amplification stage laser device 120 can be properly synchronized by determining the synchronization time difference Δt0.

[0050] Figure 5 shows the characteristics of the delay times DS1 and DS2 of switches SW1 and SW2. The characteristics of the delay times DS1 and DS2 correspond to the first and second delay characteristics in this disclosure, respectively. The horizontal axis of Figure 5 represents the number of pulses N from the first pulse of the pulsed laser light LB continuously output from the laser system 100, and the vertical axis represents the delay time DS. The delay time DS corresponds to the delay times DS1 and DS2 of switches SW1 and SW2, respectively.

[0051] The delay time DS can change depending on the number of pulses N from the first pulse, and the way it changes can differ depending on the repetition frequency of the pulsed laser beam LB. For example, as the number of pulses N from the first pulse increases, the delay time DS tends to increase, and as the number of pulses N increases further, the amount of change in the delay time DS decreases and the delay time DS tends to converge to a nearly constant value. Also, for example, as the repetition frequency of the pulsed laser beam LB increases, the amount of change in the delay time DS in response to the change in the number of pulses N increases, and the delay time DS tends to increase when it converges to a constant value. Furthermore, if the pulsed laser beam LB is output again after an oscillation pause during which it is not output for a certain period of time, the number of pulses N returns to 1, and the delay time DS returns to its initial value.

[0052] As shown in Figure 5, the delay time DS changes during operation even with the same switch. Since switches SW1 and SW2 need to have the same delay times DS1 and DS2, including these characteristics of change, switches of the same model number are used for SW1 and SW2.

[0053] 2. Issues with the Comparative Example Pulse power modules 13 and 23 are replaced when they reach the end of their service life or when their performance deteriorates. The timing of replacement may differ between pulse power module 13 and pulse power module 23. For example, when replacing pulse power module 23, it is desirable to replace it with a new pulse power module 23 that includes a switch SW2 of the same model number as the switch SW1 included in pulse power module 13.

[0054] However, there may be cases where a switch SW2 with the same model number as switch SW1 becomes unavailable, for example, due to discontinuation of production. In this case, in order to prevent synchronization issues between the oscillation stage laser device 110 and the amplification stage laser device 120, it may be necessary to replace not only the pulse power module 23 but also the pulse power module 13 to match the switch model numbers, which could incur additional costs.

[0055] The embodiments described below relate to properly synchronizing the oscillation stage laser device 110 and the amplification stage laser device 120 even if the delay time characteristics of the switches included in the pulse power modules 13 and 23 are different.

[0056] 3. Laser system 100 that readjusts the output timing of the oscillation trigger signal. 3.1 Overview Figure 6 is a time chart showing the case when switch SW2 in the comparative example is replaced with switch SW3, which has different delay time characteristics than switch SW1. Even when switch SW2 is replaced with switch SW3, it is desirable that the turn-on timing difference Δs0 of switches SW1 and SW3 remain the same as the timing difference Δs0 before the replacement (see Figure 4). Therefore, in this embodiment, the correction time Δt0122 for outputting the oscillation trigger signal Tr122 is readjusted according to the delay time DS3 of switch SW3. Switch SW3 corresponds to the third switch in this disclosure, and the characteristics of the delay time DS3 correspond to the third delay characteristics in this disclosure.

[0057] The configuration of the laser system 100 in the embodiment is the same as in the comparative example.

[0058] 3.2 Operation Figure 7 is a flowchart showing the procedure for synchronous control of the laser system 100 in the embodiment.

[0059] In S1, the laser control processor 130 acquires data on the characteristics of the delay times DS1 and DS2 of switches SW1 and SW2 before replacement. The characteristics of the delay times DS1 and DS2 do not need to be measured with switches SW1 and SW2 mounted on the laser system 100; they may be measured by connecting to a measuring instrument (not shown). Alternatively, the characteristics of the delay time of another switch having the same model number as switches SW1 and SW2 may be acquired.

[0060] In S2, the laser control processor 130 and the synchronization processor 135 perform adjustment oscillations to determine the synchronization time difference Δt0 so that the synchronization between the oscillation stage laser device 110 and the amplification stage laser device 120 is optimized. This process is the same as in the comparative example. By determining the synchronization time difference Δt0, the turn-on timing difference Δs0 of switches SW1 and SW2 is determined.

[0061] In S3, the laser control processor 130 and the synchronization processor 135 bring the laser system 100 into full operation. Here, for example, as shown in Figure 4, synchronization control is performed using correction times Δt0112 and Δt0122 corresponding to the synchronization time difference Δt0.

[0062] In S4, the laser control processor 130 determines whether the pulse power modules 13 and 23 have reached the end of their service life or have deteriorated in performance, and decides whether or not to replace one of them.

[0063] If neither pulse power module 13 nor 23 is replaced (S4: NO), the laser control processor 130 waits in the laser system 100 while it is running until S4 is determined to be YES. However, if the laser system 100 is to be stopped independently of the determination in S4, the process in this flowchart may be terminated.

[0064] If one of the pulse power modules 13 and 23 is replaced (S4: YES), the laser control processor 130 determines in S5 whether the delay time characteristics change. For example, when replacing pulse power module 23, it determines whether the delay time characteristics of the switch SW2 that was installed in pulse power module 23 and the newly installed switch SW3 are different.

[0065] If the delay time characteristics do not change (S5:NO), one of the pulse power modules 13 and 23 is replaced in S6. During the replacement work, the operation of the laser system 100 is stopped. After S6, in S3, the laser control processor 130 and the synchronization processor 135 restart the laser system 100.

[0066] If the delay time characteristics change (S5:YES), in S7, the laser control processor 130 acquires data on the characteristics of the delay time DS3 of the newly installed switch SW3. The laser control processor 130 further generates difference data between the characteristics of the delay time DS2 of the replacement switch SW2 and the characteristics of the delay time DS3 of switch SW3.

[0067] Figure 8 shows a portion of the delay time DS3 characteristic of switch SW3 superimposed on the delay time DS1 and DS2 characteristics of switches SW1 and SW2. In Figure 8, the delay time DS3 characteristic at 3kHz is shown by a dashed line. The difference in delay time when the repetition frequency is the same and the number of pulses N from the first pulse is also the same is defined as the difference DEF.

[0068] Figure 9 shows an example of the difference data created in S7 of Figure 7. In Figure 9, the horizontal axis represents the number of pulses N from the first pulse, and the vertical axis represents the difference DEF. The difference data may be created for each repetition frequency and for each number of pulses N, and the difference data may be stored in a table format.

[0069] Referring again to Figure 7, in S8, one of the pulse power modules 13 and 23 is replaced. During the replacement, the operation of the laser system 100 is stopped. After S8, in S9, the laser control processor 130 and the synchronization processor 135 restart the laser system 100.

[0070] In S10, the laser control processor 130 and the synchronization processor 135 perform correction control of the output timing of the oscillation trigger signals Tr112 and Tr122, and perform synchronization control of the laser system 100, which includes switches SW1 and SW3, which have different delay time characteristics. This process will be described later with reference to Figure 10.

[0071] After S10, the laser control processor 130 waits in the laser system 100 while it is running, until it is determined to be YES in S4. Even if one of the pulse power modules 13 and 23 is replaced, it is not necessary to reset the synchronization time difference Δt0, so it is not necessary to return to S2. If the laser system 100 is to be stopped independently of the determination in S4, the processing in this flowchart may be terminated.

[0072] Figure 10 is a flowchart showing the procedure for correcting the output timing of the oscillation trigger signals Tr112 and Tr122 in the embodiment. The process shown in Figure 10 corresponds to the subroutine S10 in Figure 7.

[0073] In S11, when the laser control processor 130 receives the oscillation command Tr0 from the exposure control processor 230, the synchronous processor 135 outputs oscillation trigger signals Tr112 and Tr122 at the output timing determined using the initial characteristics. The initial characteristics are, for example, the difference DEF when the number of pulses N in the difference data shown in Figure 9 is 1. The initial characteristics reflect the difference between the delay time DS2 characteristic data of the replaced switch SW2 and the delay time DS3 characteristic data of the switch SW3, but are independent of the repetition frequency.

[0074] In S12, the synchronous processor 135 determines the repetition frequency based on the difference between the time of the next oscillation command Tr0 and the time of the immediately preceding oscillation command Tr0. The immediately preceding oscillation command Tr0 corresponds to the first oscillation command in this disclosure, and the next oscillation command Tr0 corresponds to the second oscillation command in this disclosure. Here, the reciprocal of the time interval of the most recent oscillation command Tr0 is used as the repetition frequency, and by reflecting this repetition frequency in the recorrection in S14, it is possible to respond immediately to changes in the time interval of the oscillation command Tr0.

[0075] In S13, the synchronous processor 135 determines whether the repetition frequency is above a threshold. For example, if the repetition frequency is 100 Hz or higher, it is determined that the repetition frequency is above the threshold. If the repetition frequency is below the threshold (S13: NO), the process returns to S11 and outputs oscillation trigger signals Tr112 and Tr122 at timings determined using the initial characteristics. If the repetition frequency is above the threshold (S13: YES), the process proceeds to S14.

[0076] In S14, the synchronous processor 135 recorrects the correction time Δt0112 or Δt0122 using the delay time DS obtained by applying the repetition frequency and pulse number N to the differential data. For example, if the pulse power module 23 is replaced with a pulse power module including switch SW3, the value DS2-DS3 obtained by subtracting the delay time DS3 of switch SW3 from the delay time DS2 of switch SW2 is added to the current correction time Δt0122 (see Figure 4) to obtain a new correction time Δt0122 (see Figure 6). This suppresses fluctuations in the turn-on timing difference Δs0 of switches SW1 and SW3. Alternatively, the fluctuations in the turn-on timing difference Δs0 of switches SW1 and SW3 can also be suppressed by subtracting DS2-DS3 from the current correction time Δt0112. DS2-DS3 are obtained from the differential data.

[0077] In S15, the synchronous processor 135 outputs oscillation trigger signals Tr112 and Tr122 at output timings determined using correction times Δt0112 and Δt0122. One of the correction times Δt0112 and Δt0122 is the correction time recorrected in S14.

[0078] In S16, the synchronous processor 135 determines whether the laser control processor 130 has received the next oscillation command Tr0 within a certain time period. This certain time period may be, for example, 1 second. If the next oscillation command Tr0 is received within the certain time period (S16: YES), the synchronous processor 135 returns to S12. If the next oscillation command Tr0 is not received within the certain time period (S16: NO), the synchronous processor 135 terminates the processing in this flowchart.

[0079] This document describes a case where differential data is created to correct one of the correction times Δt0112 and Δt0122, but the disclosure is not limited thereto. Differential data does not need to be created, and both correction times Δt0112 and Δt0122 may be corrected. For example, if a pulse power module 23 including switch SW2 is replaced with a pulse power module including switch SW3, the delay time DS3 of switch SW3 may be added to the current correction time Δt0112, and the delay time DS2 of switch SW2 may be added to the current correction time Δt0122. In this case as well, fluctuations in the turn-on timing difference Δs0 of switches SW1 and SW3 can be suppressed.

[0080] 3.3 Effect (1) According to one embodiment, the laser system 100 comprises an oscillation stage laser device 110 including a pulse power module 13, an amplification stage laser device 120 including a pulse power module 23, and a laser control processor 130 or a synchronization processor 135. The laser control processor 130 or synchronization processor 135 determines the timing difference Δs0 from when a switch SW1 having a first delay characteristic included in the pulse power module 13 is turned on until a switch SW2 having a second delay characteristic included in the pulse power module 23 is turned on, so that the oscillation stage laser device 110 and the amplification stage laser device 120 are synchronized, and controls the output timing of the oscillation trigger signal Tr112 input to the pulse power module 13 and the oscillation trigger signal Tr122 input to the pulse power module 23. The laser control processor 130 or the synchronization processor 135 corrects the output timing of at least one of the oscillation trigger signals Tr112 and Tr122 so as to suppress changes in the timing difference Δs0 when either switch SW1 or switch SW2 is replaced with switch SW3 having a third delay characteristic.

[0081] According to this, by correcting the output timing of the oscillation trigger signal Tr112 or Tr122 according to the delay characteristics of the switches included in the pulse power modules 13 and 23, the oscillation stage laser device 110 and the amplification stage laser device 120 can be synchronized even when switches with different delay characteristics are used. When it becomes necessary to replace one of the switches in the oscillation stage laser device 110 or the amplification stage laser device 120, it is not necessary to replace the other switch with a switch that has the same characteristics, thus reducing maintenance costs.

[0082] (2) According to the embodiment, each of the first delay characteristic, the second delay characteristic, and the third delay characteristic includes a relationship between the number of pulses N from the first pulse of the pulsed laser light LB continuously output from the laser system 100 and the delay time DS from the output timing of the oscillation trigger signal Tr112 or Tr122 to turn-on. The laser control processor 130 or the synchronization processor 135 corrects the output timing based on the number of pulses N.

[0083] According to this, by correcting the output timing of the oscillation trigger signal Tr112 or Tr122 according to the delay time DS which changes according to the number of pulses N from the first pulse, it is possible to suppress changes in the turn-on timing difference Δs0 of the switches included in the pulse power modules 13 and 23.

[0084] (3) According to the embodiment, when the repetition frequency of the pulsed laser light LB is less than a threshold, the laser control processor 130 or the synchronization processor 135 corrects the output timing of the oscillation trigger signal Tr112 or Tr122 using the delay time DS with the number of pulses N as the minimum value.

[0085] According to this, when the repetition frequency is low and the delay time DS is less affected by the previous pulse, high-precision correction can be achieved by correcting it as the leading pulse.

[0086] (4) According to the embodiment, each of the first delay characteristic, the second delay characteristic, and the third delay characteristic includes a relationship between the repetition frequency of the pulsed laser light LB output by the laser system 100 and the delay time DS from the output timing of the oscillation trigger signal Tr112 or Tr122 to turn-on. The laser control processor 130 or the synchronous processor 135 corrects the output timing based on the repetition frequency.

[0087] According to this, by correcting the output timing of the oscillation trigger signal Tr112 or Tr122 in accordance with the delay time DS which changes according to the repetition frequency of the pulsed laser light LB, it is possible to suppress changes in the turn-on timing difference Δs0 of the switches included in the pulsed power modules 13 and 23.

[0088] (5) According to the embodiment, when the repetition frequency is less than a threshold, the laser control processor 130 or the synchronization processor 135 corrects the output timing of the oscillation trigger signal Tr112 or Tr122 using a constant value that does not depend on the repetition frequency.

[0089] According to this, when the repetition frequency is low and the delay time DS is less affected by the previous pulse, high-precision correction can be achieved by correcting it with a constant value.

[0090] (6) According to the embodiment, the laser control processor 130 or the synchronous processor 135 receives a first oscillation command Tr0 for outputting a first pulse of pulsed laser light LB and a second oscillation command Tr0 for outputting a second pulse of pulsed laser light LB following the first pulse, and determines the repetition frequency based on the time difference between the first oscillation command Tr0 and the second oscillation command Tr0.

[0091] According to this, by determining the repetition frequency based on the time difference between the first and second oscillation commands Tr0, appropriate correction can be made even when the repetition frequency changes.

[0092] (7) According to the embodiment, the laser control processor 130 or the synchronization processor 135 corrects the output timing of the oscillation trigger signal Tr112 or Tr122 based on the time difference between the most recent first and second oscillation commands Tr0.

[0093] According to this, by applying a correction based on the repetition frequency determined from the most recent first and second oscillation commands Tr0, appropriate corrections can be made quickly even when the repetition frequency changes.

[0094] (8) According to the embodiment, the laser control processor 130 or the synchronous processor 135 corrects the output timing based on the number of pulses N and the repetition frequency.

[0095] According to this, by correcting the output timing of the oscillation trigger signal Tr112 or Tr122 in accordance with the delay time DS which changes according to both the number of pulses N from the first pulse and the repetition frequency of the pulsed laser light LB, it is possible to suppress changes in the turn-on timing difference Δs0 of the pulsed power modules 13 and 23.

[0096] (9) According to the embodiment, the laser control processor 130 or the synchronization processor 135 corrects the output timing of either the oscillation trigger signal Tr112 or the oscillation trigger signal Tr122, whichever of the switches SW1 and SW2 is replaced by switch SW3.

[0097] According to this, by correcting the output timing of the oscillation trigger signal Tr112 or Tr122 that has been replaced by switch SW3, the output timing of the oscillation trigger signal Tr112 or Tr122 that has not been replaced is maintained, enabling stable control.

[0098] (10) According to the embodiment, the laser control processor 130 or the synchronization processor 135 corrects the output timing of the oscillation trigger signal Tr112 or Tr122 based on the difference DEF between the delay characteristic of either the first or second delay characteristic which is replaced by switch SW3 among switches SW1 and SW2, and the third delay characteristic.

[0099] According to this, by correcting the output timing of the oscillation trigger signal Tr112 or Tr122 based on the difference DEF of the delay characteristics of the old and new switches that have been replaced, the turn-on timing difference Δs0 of the switches included in the pulse power modules 13 and 23 is maintained before and after the replacement, enabling stable control.

[0100] (11) According to the embodiment, the laser control processor 130 or the synchronous processor 135 holds differential DEF data in a table format.

[0101] According to this method, by maintaining a table format containing the difference in DEF (Delay Factor) between the old and new switches that have been replaced, the computational load can be reduced, enabling rapid control.

[0102] (12) In this embodiment, the laser control processor 130 or the synchronization processor 135 may correct the output timing of both the oscillation trigger signals Tr112 and Tr122.

[0103] According to this, by correcting the output timing of both the oscillation trigger signals Tr112 and Tr122, it is possible to make corrections that accurately reflect the delay characteristics of the two switches included in the oscillation stage laser device 110 and the amplification stage laser device 120, respectively.

[0104] In other respects, the embodiment is the same as the comparative example.

[0105] 4. Others 4.1 Processor Processors such as the laser control processor 130, the synchronization processor 135, and the exposure control processor 230 may be physically configured in hardware form to perform the various processes included in this disclosure. For example, the processor may be a computer including a memory storing control programs that define the various processes, and a processing unit that executes the control programs. The control programs may be stored in a single memory, or they may be divided and stored in multiple physically separate memories, and the various processes may be defined by the control program as a collection of these memories. The processing unit may be a general-purpose processing unit such as a CPU, or a purpose-specific processing unit such as a GPU.

[0106] Furthermore, the processor may be programmed in software form to perform the various processes included in this disclosure. For example, the processor may have functions for performing the various processes implemented in a dedicated device such as an ASIC or a programmable device such as an FPGA.

[0107] The various processes included in this disclosure may be performed by one computer, one dedicated device, or one programmable device, or by the cooperation of multiple computers, multiple dedicated devices, or multiple programmable devices located physically separately. The various processes may be performed by at least two combinations of one or more computers, one or more dedicated devices, and one or more programmable devices.

[0108] 4.2 Supplement The above description is intended to be illustrative, not restrictive. Therefore, it will be apparent to those skilled in the art that modifications can be made to the embodiments of this disclosure without departing from the claims. It will also be apparent to those skilled in the art that the embodiments of this disclosure can be used in combination.

[0109] Terms used throughout this specification and the claims should be interpreted as "non-limiting" unless otherwise specified. For example, terms such as "includes," "have," "equip," and "possess" should be interpreted as "not excluding the existence of components other than those described." Also, the modifier "one" should be interpreted as "at least one" or "one or more." Furthermore, the term "at least one of A, B, and C" should be interpreted as "A," "B," "C," "A+B," "A+C," "B+C," or "A+B+C." In addition, it should be interpreted as including combinations of these with anything other than "A," "B," and "C."

Claims

1. An oscillator stage laser device including a first pulse compression circuit, An amplified laser device including a second pulse compression circuit, A processor that determines the timing difference between the time a first switch having a first delay characteristic in the first pulse compression circuit is turned on and the time a second switch having a second delay characteristic in the second pulse compression circuit is turned on, so that the oscillation stage laser device and the amplification stage laser device are synchronized, and controls the output timing of the first oscillation trigger signal input to the first pulse compression circuit and the second oscillation trigger signal input to the second pulse compression circuit, wherein if either the first switch or the second switch is replaced with a third switch having a third delay characteristic, the processor corrects the output timing of at least one of the first oscillation trigger signal and the second oscillation trigger signal so that the change in the timing difference is suppressed. A laser system equipped with [the following features].

2. A laser system according to claim 1, Each of the first delay characteristic, the second delay characteristic, and the third delay characteristic includes a relationship between the number of pulses from the first pulse of the pulsed laser light continuously output from the laser system and the corresponding delay time from the output timing to turn-on. The processor corrects the timing of at least one of the output pulses based on the number of pulses. Laser system.

3. The laser system according to claim 2, The processor corrects the output timing of at least one of the pulses when the repetition frequency of the pulsed laser light is less than a threshold, using the delay time when the number of pulses is set to the minimum value. Laser system.

4. A laser system according to claim 1, Each of the first delay characteristic, the second delay characteristic, and the third delay characteristic includes the relationship between the repetition frequency of the pulsed laser light output by the laser system and the corresponding delay time from the output timing to turn-on. The processor corrects the timing of at least one of the output timings based on the repetition frequency. Laser system.

5. A laser system according to claim 4, The processor corrects at least one of the output timings using a constant value that does not depend on the repetition frequency when the repetition frequency is below a threshold. Laser system.

6. A laser system according to claim 4, The processor receives a first oscillation command for outputting a first pulse of the pulsed laser light and a second oscillation command for outputting a second pulse of the pulsed laser light following the first pulse, and determines the repetition frequency based on the time difference between the first oscillation command and the second oscillation command. Laser system.

7. A laser system according to claim 6, The processor corrects the output timing of at least one of the most recent first and second oscillation commands based on the time difference between them. Laser system.

8. A laser system according to claim 1, Each of the first delay characteristic, the second delay characteristic, and the third delay characteristic includes the relationship between the number of pulses from the leading pulse of the pulsed laser light continuously output from the laser system, the repetition frequency of the pulsed laser light, and the corresponding delay time from the output timing to turn-on. The processor corrects the timing of at least one of the output pulses based on the number of pulses and the repetition frequency. Laser system.

9. A laser system according to claim 1, The processor corrects the output timing of either the first oscillation trigger signal or the second oscillation trigger signal, whichever of the first and second switches is replaced by the third switch. Laser system.

10. A laser system according to claim 9, The processor corrects the output timing of the oscillation trigger signal of the first switch and the second switch that has been replaced by the third switch, based on the difference between the first delay characteristic and the second delay characteristic, whichever of the first and second switches has been replaced by the third switch, and the third delay characteristic. Laser system.

11. A laser system according to claim 10, The processor stores the difference data in a table format. Laser system.

12. A laser system according to claim 1, The processor corrects the output timing of both the first oscillation trigger signal and the second oscillation trigger signal. Laser system.

13. An oscillator stage laser device including a first pulse compression circuit, An amplified laser device including a second pulse compression circuit, A method for adjusting a laser system comprising: To synchronize the oscillation stage laser device and the amplification stage laser device, the timing difference is determined from the time the first switch, which is included in the first pulse compression circuit and has a first delay characteristic, is turned on until the second switch, which is included in the second pulse compression circuit and has a second delay characteristic, is turned on. When either the first switch or the second switch is replaced with a third switch having a third delay characteristic, the output timing of at least one of the first oscillation trigger signal input to the first pulse compression circuit and the second oscillation trigger signal input to the second pulse compression circuit is corrected so as to suppress the change in the timing difference. How to adjust a laser system.

14. A method for adjusting a laser system according to claim 13, Each of the first delay characteristic, the second delay characteristic, and the third delay characteristic includes a relationship between the number of pulses from the first pulse of the pulsed laser light continuously output from the laser system and the corresponding delay time from the output timing to turn-on. The output timing of at least one of the above is corrected based on the number of pulses. How to adjust a laser system.

15. A method for adjusting a laser system according to claim 13, Each of the first delay characteristic, the second delay characteristic, and the third delay characteristic includes the relationship between the repetition frequency of the pulsed laser light output by the laser system and the corresponding delay time from the output timing to turn-on. The output timing of at least one of the above is corrected based on the repetition frequency. How to adjust a laser system.

16. A method for adjusting a laser system according to claim 13, Each of the first delay characteristic, the second delay characteristic, and the third delay characteristic includes the relationship between the number of pulses from the leading pulse of the pulsed laser light continuously output from the laser system, the repetition frequency of the pulsed laser light, and the corresponding delay time from the output timing to turn-on. The output timing of at least one of the above is corrected based on the number of pulses and the repetition frequency. How to adjust a laser system.

17. A method for manufacturing electronic devices, An oscillator stage laser device including a first pulse compression circuit, An amplified laser device including a second pulse compression circuit, A processor that determines the timing difference between the time a first switch having a first delay characteristic in the first pulse compression circuit is turned on and the time a second switch having a second delay characteristic in the second pulse compression circuit is turned on, so that the oscillation stage laser device and the amplification stage laser device are synchronized, and controls the output timing of the first oscillation trigger signal input to the first pulse compression circuit and the second oscillation trigger signal input to the second pulse compression circuit, wherein if either the first switch or the second switch is replaced with a third switch having a third delay characteristic, the processor corrects the output timing of at least one of the first oscillation trigger signal and the second oscillation trigger signal so that the change in the timing difference is suppressed. A laser system equipped with the above generates pulsed laser light, The pulsed laser light is output to the exposure apparatus, To manufacture the aforementioned electronic device, the pulsed laser light is exposed onto a photosensitive substrate in the exposure apparatus. A method for manufacturing electronic devices, including the following.

18. A method for manufacturing an electronic device according to claim 17, Each of the first delay characteristic, the second delay characteristic, and the third delay characteristic includes a relationship between the number of pulses from the first pulse of the pulsed laser light continuously output from the laser system and the corresponding delay time from the output timing to turn-on. The processor corrects the timing of at least one of the output pulses based on the number of pulses. A method for manufacturing electronic devices.

19. A method for manufacturing an electronic device according to claim 17, Each of the first delay characteristic, the second delay characteristic, and the third delay characteristic includes the relationship between the repetition frequency of the pulsed laser light and the corresponding delay time from the output timing to turn-on. The processor corrects the timing of at least one of the output timings based on the repetition frequency. A method for manufacturing electronic devices.

20. A method for manufacturing an electronic device according to claim 17, Each of the first delay characteristic, the second delay characteristic, and the third delay characteristic includes the relationship between the number of pulses from the leading pulse of the pulsed laser light continuously output from the laser system, the repetition frequency of the pulsed laser light, and the corresponding delay time from the output timing to turn-on. The processor corrects the timing of at least one of the output pulses based on the number of pulses and the repetition frequency. A method for manufacturing electronic devices.

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