Laser processing system, laser processing method, and method for manufacturing electronic device

Abstract

To provide a laser processing system related to one viewpoint.SOLUTION: A laser processing system includes: a laser device for outputting a deep ultraviolet laser beam in response to reception of a light emission trigger signal; an optical isolator including a polarizer and a deep ultraviolet light transmission element which are arranged on the optical path of the laser beam, and a piezo element connected to the deep ultraviolet light transmission element; and a processor for supplying a driving signal whose voltage is changed by characteristic frequency of the deep ultraviolet light transmission element to the piezo element, and transmitting a light emission trigger signal to the laser device with the characteristic frequency or a frequency obtained by frequency-dividing the characteristic frequency as a repetitive frequency, so that the deep ultraviolet light transmission element functions as a 1 / 4 wavelength plate by stress birefringence generated according to force applied from the piezo element at a timing at which the laser beam passes through the deep ultraviolet light transmission element, and irradiates a workpiece with the laser beam emitted from the optical isolator and processes the workpiece.SELECTED DRAWING: Figure 5

Description

Technical Field

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

Background Art

[0002] In recent years, in semiconductor exposure apparatuses, as semiconductor integrated circuits have been miniaturized and 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 device for exposure, a KrF excimer laser device that outputs laser light with a wavelength of about 248.0 nm and an ArF excimer laser device that outputs laser light with a wavelength of about 193.4 nm are used.

[0003] Further, since excimer laser light has a pulse width of about several 10 ns and short wavelengths of 248.0 nm and 193.4 nm, respectively, it may be used for direct processing of polymer materials, glass materials, and the like.

[0004] Chemical bonds in polymer materials can be broken by excimer laser light having photon energy higher than the bond energy. Therefore, non-thermal processing of polymer materials is possible with excimer laser light, and it is known that the processed shape becomes neat.

[0005] Further, since glass, ceramics, etc. have a high absorption rate for excimer laser light, it is known that even materials that are difficult to process with visible and infrared laser light can be processed with excimer laser light.

[0006] The spectral linewidth of the spontaneous emission light of a KrF excimer laser device and an ArF excimer laser device is as wide as 350 pm to 400 pm. Therefore, when 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. Therefore, it is necessary to narrow the spectral linewidth of the laser light output from the gas laser device until the chromatic aberration becomes negligible. For this purpose, a line narrowing module (LNM: Line Narrowing Module) including a line narrowing element (etalon, grating, etc.) may be provided in the laser resonator of the gas laser device to narrow the spectral linewidth. Hereinafter, a gas laser device whose spectral linewidth is narrowed is referred to as a line-narrowed gas laser device.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Patent Document 2

[0008] A laser processing system according to one aspect of the present disclosure includes a laser device that outputs deep ultraviolet laser light in response to reception of a light emission trigger signal, a polarizer and a deep ultraviolet light transmitting element disposed on the optical path of the laser light, and a piezo element connected to the deep ultraviolet light transmitting element, an optical isolator including the piezo element, a processor that supplies a drive signal whose voltage changes at the natural frequency of the deep ultraviolet light transmitting element to the piezo element, and transmits the light emission trigger signal to the laser device with the natural frequency or a frequency obtained by dividing the natural frequency as a repetition frequency so that the deep ultraviolet light transmitting element functions as a quarter-wave plate due to stress birefringence generated in response to the force applied from the piezo element at the timing when the laser light passes through the deep ultraviolet light transmitting element, and irradiates the workpiece with the laser light emitted from the optical isolator to perform processing.

[0009] A laser processing method according to one aspect of the present disclosure irradiates a workpiece with a laser processing system including an optical isolator including a laser device that outputs deep ultraviolet laser light in response to reception of a light emission trigger signal, a polarizer and a deep ultraviolet light transmitting element disposed on the optical path of the laser light, and a piezoelectric element connected to the deep ultraviolet light transmitting element, and performs processing, including supplying a drive signal whose voltage changes at the natural frequency of the deep ultraviolet light transmitting element to the piezoelectric element, and transmitting the light emission trigger signal to the laser device with the natural frequency or a frequency obtained by dividing the natural frequency as a repetition frequency so that the deep ultraviolet light transmitting element functions as a quarter-wave plate due to stress birefringence generated in response to the force applied from the piezoelectric element at the timing when the laser light passes through the deep ultraviolet light transmitting element, and irradiating the workpiece with the laser light emitted from the optical isolator to perform processing.

[0010] A method for manufacturing an electronic device according to one aspect of the present disclosure includes a laser device that outputs deep ultraviolet laser light in response to reception of a light emission trigger signal, a polarizer and a deep ultraviolet light transmitting element disposed on the optical path of the laser light, an optical isolator including a piezoelectric element connected to the deep ultraviolet light transmitting element, a processor that supplies a drive signal whose voltage changes at the natural frequency of the deep ultraviolet light transmitting element to the piezoelectric element, and transmits the light emission trigger signal to the laser device with the natural frequency or a frequency obtained by dividing the natural frequency as a repetition frequency so that the deep ultraviolet light transmitting element functions as a quarter-wave plate due to stress birefringence generated in response to the force applied from the piezoelectric element at the timing when the laser light passes through the deep ultraviolet light transmitting element, and forming a plurality of through holes in a glass substrate as a workpiece by a laser processing system that irradiates the workpiece with the laser light emitted from the optical isolator to perform processing, coupling an interposer having the glass substrate and conductors provided in each of the plurality of through holes, and an integrated circuit chip to electrically connect them to each other, and coupling the interposer and a circuit board to electrically connect them to each other.

Brief Description of the Drawings

[0011] Some embodiments of the present disclosure will be described below by way of example only with reference to the accompanying drawings.

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[0012] <Content> 1. Explanation of Terms 1.1 Polarizer 1.2 Quarter-Wave Plate 2. Comparative Example 2.1 Configuration 2.2 Operation 2.3 Problems 3. First Embodiment 3.1 Configuration 3.2 Operation 3.3 Effects 4. Second Embodiment 4.1 Configuration 4.2 Operation 4.3 Effects 5. Modification Example of Laser Device 6. Method for Manufacturing Electronic Device 7. Configuration Example of Laser Processing Processor

[0013] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. The embodiments described below show some examples of the present disclosure and do not limit the content of the present disclosure. Also, not all of the configurations and operations described in each embodiment are essential as the configurations and operations of the present disclosure. Note that the same reference numerals are assigned to the same components, and redundant descriptions are omitted.

[0014] 1. Explanation of Terms 1.1 Polarizer In the present disclosure, a polarizer is an optical element that separates incident light into two linearly polarized lights with orthogonal polarization directions. Specifically, the polarizer according to the present disclosure is an optical element that transmits one of the two linearly polarized lights with orthogonal polarization directions and reflects the other.

[0015] 1.2 Quarter-Wave Plate In the present disclosure, a quarter-wave plate is an optical element that gives a phase difference to two orthogonal polarization components, and the phase difference is 90° + n × 180°. Here, n is an integer of 0 or more. Note that the phase difference for the optical element to actually function as a quarter-wave plate may include an error of about several degrees based on 90° + n × 180°.

[0016] 2. Comparative Example 2.1 Configuration FIG. 1 schematically shows the configuration of a laser processing system 1 according to the comparative example. Note that the comparative example is a form recognized by the applicant as being known only to the applicant and is not a known example recognized by the applicant.

[0017] The laser processing system 1 mainly includes a laser device 2 and a laser processing device 4. The laser processing system 1 is used for laser hole processing to form holes such as via holes in a glass substrate for an interposer.

[0018] The laser device 2 is a laser device that outputs deep ultraviolet pulsed laser light. For example, the laser device 2 is an ArF excimer laser device that uses an ArF laser gas containing argon (Ar) and fluorine (F) as the laser gas. The laser device 2 outputs deep ultraviolet pulsed laser light with a center wavelength of about 193.4 nm and linearly polarized light. Hereinafter, the deep ultraviolet pulsed laser light output by the laser device 2 is simply referred to as laser light L. Note that the deep ultraviolet pulsed laser light is an example of the "deep ultraviolet laser light" according to the technology of the present disclosure. Also, deep ultraviolet refers to a wavelength range of, for example, 100 nm to 280 nm.

[0019] The laser device 2 and the laser processing device 4 are connected by an optical path tube 5. The optical path tube 5 is arranged on the optical path of the laser light L between the exit of the laser device 2 and the entrance of the laser processing device 4.

[0020] The laser processing device 4 includes a laser processing processor 40, an optical device 41, a frame 42, a moving stage 43, and a table 44. The optical device 41 and the moving stage 43 are fixed to the frame 42.

[0021] The table 44 supports the workpiece 45. The workpiece 45 is a processing target on which the laser light L is irradiated for laser hole processing. For example, the workpiece 45 is a quartz glass substrate.

[0022] The moving stage 43 supports the table 44. The workpiece 45 is fixed on the table 44. The moving stage 43 is movable in the X direction, Y direction, and Z direction, and the position of the workpiece 45 can be adjusted by adjusting the position of the table 44. The X direction, Y direction, and Z direction are orthogonal to each other. The X direction and Y direction are parallel to the surface 45a on which the laser beam L of the workpiece 45 is incident. The Z direction is orthogonal to the surface 45a.

[0023] The moving stage 43 adjusts the position of the workpiece 45 under the control of the laser processing processor 40 so that the laser beam L emitted from the optical device 41 irradiates a desired processing position on the surface 45a.

[0024] The optical device 41 includes a housing 41a, a window 46, high reflection mirrors 47a, 47b, 47c, an attenuator 48, a condensing optical system 49, and an optical isolator 50. The high reflection mirrors 47a, 47b, 47c, the attenuator 48, the condensing optical system 49, and the optical isolator 50 are provided inside the housing 41a. The window 46 is on the optical path between the condensing optical system 49 and the moving stage 43, and is arranged in a hole formed in the housing 41a via an O-ring (not shown) or the like.

[0025] The housing 41a is provided with a suction port 41b for sucking nitrogen gas into the housing 37 and a discharge port 41c for discharging nitrogen gas from the housing 41a to the outside. A nitrogen gas supply source (not shown) is connected to the suction port 41b. A discharge device (not shown) is connected to the discharge port 41c. The suction port 41b and the discharge port 41c are sealed by an O-ring (not shown) so as to suppress the entry of outside air into the housing 41a.

[0026] The high reflection mirrors 47a, 47b, 47c are respectively fixed to holders (not shown). The high reflection mirror 47a is arranged to reflect the laser beam L that has passed through the optical path tube 5 so that the reflected laser beam L passes through the attenuator 48 and enters the high reflection mirror 47b.

[0027] The attenuator 48 is disposed on the optical path between the high-reflection mirror 47a and the high-reflection mirror 47b within the housing 41a. The attenuator 48 includes, for example, two partial reflection mirrors 48a and 48b, and rotation stages 48c and 48d for these partial reflection mirrors. The partial reflection mirrors 48a and 48b are optical elements whose transmittance changes depending on the incident angle of the laser beam L. The incident angle of the laser beam L is adjusted for the partial reflection mirrors 48a and 48b by the rotation stages 48c and 48d.

[0028] The high-reflection mirror 47b reflects the laser beam L that has passed through the attenuator 48, and is arranged such that the reflected laser beam L is incident on the high-reflection mirror 47c.

[0029] The optical isolator 50 includes a polarizer 51 and a quarter-wave plate 52, and is disposed on the optical path of the laser beam L reflected by the high-reflection mirror 47c. For example, the polarizer 51 is a polarizing beam splitter that transmits p-polarized light and reflects s-polarized light, and is arranged such that the laser beam L is incident as p-polarized light.

[0030] The quarter-wave plate 52 is disposed on the optical path of the laser beam L that has passed through the polarizer 51, and is arranged to convert the incident laser beam L from linearly polarized light to circularly polarized light and emit it. Specifically, the quarter-wave plate 52 is arranged such that the azimuth angle of the polarization direction of the laser beam L with respect to its fast axis or slow axis is 45°.

[0031] The condensing optical system 49 is fixed to the holder 49a, and is arranged to condense the laser beam L emitted from the optical isolator 50 onto the workpiece 45 through the window 46.

[0032] The laser processing processor 40 transmits the target pulse energy Et and the emission trigger signal Tr to the laser device 2. The target pulse energy Et is the target value of the pulse energy of the laser beam L. The emission trigger signal Tr is a trigger signal for causing the laser device 2 to output one pulse of the laser beam L, and is generated based on a master signal having a predetermined frequency. The laser processing processor 40 is an example of the "processor" according to the technology of the present disclosure.

[0033] FIG. 2 schematically shows the configuration of the laser device 2. The laser device 2 includes a laser processor 20, a master oscillator 21a, and an excimer amplifier 21b. In this comparative example, the excimer amplifier 21b is a power oscillator as an oscillation amplifier.

[0034] The master oscillator 21a is an excimer laser device including a charger 22a, a power supply 23a, a rear mirror 24a, a chamber 25a, and an output coupling mirror 26a. A pair of discharge electrodes 27a are provided in the chamber 25a, and the above-described laser gas is enclosed therein. Further, a pair of windows 28a are provided in the chamber 25a at positions where the laser beam L passes through. The pair of windows 28a are arranged such that the incident angle of the laser beam L becomes the Brewster angle. The rear mirror 24a and the output coupling mirror 26a constitute an optical resonator.

[0035] The power supply 23a is a pulse power module to which the charger 22a is connected. The rear mirror 24a is a total reflection mirror. The output coupling mirror 26a is a partial reflection mirror having a reflectivity of the laser beam L within the range of 40% to 60%.

[0036] The excimer amplifier 21b includes a charger 22b, a power supply 23b, a rear mirror 24b, a chamber 25b, and an output coupling mirror 26b. Inside the chamber 25b, a pair of discharge electrodes 27b are provided, and the above-described laser gas is enclosed. Further, in the chamber 25b, a pair of windows 28b are provided at positions through which the laser beam L passes. The pair of windows 28b are arranged such that the incident angle of the laser beam L becomes the Brewster angle. The rear mirror 24b and the output coupling mirror 26b constitute an optical resonator.

[0037] The power supply 23b is a pulse power module to which the charger 22b is connected. The rear mirror 24b is a partial reflection mirror with a reflectivity of the laser beam L in the range of 50% to 90%.

[0038] The laser processor 20 controls the charger 22a and the power supply 23a of the master oscillator 21a and the charger 22b and the power supply 23b of the excimer amplifier 21b. Specifically, the laser processor 20 sets charging voltages for the chargers 22a and 22b respectively, and controls the on / off of switches included in the power supplies 23a and 23b respectively.

[0039] 2.2 Operation Next, the operation of the laser processing system 1 according to the comparative example will be described. First, the laser processing processor 40 controls the moving stage 43 to adjust the position of the workpiece 45 so that the beam waist position of the laser beam L focused by the focusing optical system 49 is inside the workpiece 45 and at a predetermined depth from the surface 45a.

[0040] Next, the laser processing processor 40 transmits the target pulse energy Et to the laser device 2 and controls the transmittance of the attenuator 48 so that the fluence of the laser beam L irradiated on the surface 45a of the workpiece 45 reaches the target value.

[0041] Next, the laser processing processor 40 transmits a light emission trigger signal Tr with a predetermined number of pulses at a predetermined repetition frequency f L to the laser device 2.

[0042] When the laser processor 20 receives the emission trigger signal Tr, it sets the charging voltages of the chargers 22a and 22b according to the target pulse energy Et. Further, the laser processor 20 controls each switch of the power supplies 23a and 23b so that the excimer amplifier 21b discharges and amplifies the laser beam L at the timing when the laser beam L generated by the discharge in the master oscillator 21a passes through the excimer amplifier 21b.

[0043] As a result, the laser beam L is output from the laser device 2 in synchronization with the emission trigger signal Tr and enters the optical device 41 of the laser processing device 4. The laser beam L that has entered the optical device 41 is reflected by the high reflection mirror 47a and enters the attenuator 48. The laser beam L that has entered the attenuator 48 passes through the partial reflection mirrors 48a and 48b and enters the high reflection mirror 47b.

[0044] The laser beam L reflected by the high reflection mirror 47b is reflected by the high reflection mirror 47c and enters the optical isolator 50. The laser beam L that has entered the optical isolator 50 passes through the polarizer 51 and the quarter-wave plate 52 and enters the condensing optical system 49. The laser beam L that has entered the condensing optical system 49 is condensed inside the workpiece 45 from the surface 45a to a predetermined depth through the window 46.

[0045] By repeatedly irradiating the workpiece 45 with the laser beam L, the workpiece 45 is drilled. Note that there is a concern that a part of the laser beam L incident on the workpiece 45 is reflected by the surface 45a and returns as the return light Lr through the window 46 to the optical device 41, damaging the optical elements in the optical device 41. The optical isolator 50 has the function of suppressing the return light Lr from returning to the upstream side in the optical device 41.

[0046] FIG. 3 and FIG. 4 illustrate the operation of the optical isolator 50 according to the comparative example. FIG. 3 shows a state where the laser beam L enters the optical isolator 50 from the upstream side. FIG. 4 shows a state where the return light Lr enters the optical isolator 50 from the downstream side.

[0047] As shown in FIG. 3, laser light L of linearly polarized light is incident on the optical isolator 50 from the upstream side. The laser light L incident on the optical isolator 50 is incident on the polarizer 51 as p-polarized light, passes through the polarizer 51, and is incident on the quarter-wave plate 52. The laser light L of p-polarized light incident on the quarter-wave plate 52 is converted into circularly polarized light by the quarter-wave plate 52 and emitted from the optical isolator 50.

[0048] As shown in FIG. 4, the return light Lr of circularly polarized light is incident on the optical isolator 50 from the downstream side. The return light Lr incident on the optical isolator 50 is incident on the quarter-wave plate 52 and converted into linearly polarized light. The polarization direction of the return light Lr converted into linearly polarized light is orthogonal to the polarization direction of the laser light L incident on the quarter-wave plate 52 from the upstream side. For this reason, the return light Lr is incident on the polarizer 51 as s-polarized light and is reflected by the polarizer 51. Thereby, the return of the return light Lr to the upstream side of the optical isolator 50 is suppressed.

[0049] 2.3 Problems Next, the problems of the laser processing system 1 according to the comparative example will be described. The optical isolator 50 used in the laser processing system 1 according to the comparative example includes a quarter-wave plate 52 for converting linearly polarized light into circularly polarized light and converting circularly polarized light into linearly polarized light, as described above. The quarter-wave plate 52 is formed of magnesium fluoride, sapphire, quartz, etc., and has a problem of low durability against deep ultraviolet light used as the laser light L. For this reason, it has been an issue to realize an optical isolator with high durability against deep ultraviolet light.

[0050] 3. First Embodiment The laser processing system 1a according to the first embodiment of the present disclosure will be described. Note that the same components as those described above are denoted by the same reference numerals, and redundant descriptions are omitted unless otherwise specified.

[0051] 3.1 Configuration FIG. 5 schematically shows the configuration of the laser processing system 1a according to the first embodiment. The laser processing system 1a differs from the configuration of the laser processing system 1 according to the comparative example only in that an optical isolator 50a is used instead of the optical isolator 50 according to the comparative example.

[0052] The optical isolator 50a includes a polarizer 51 and a photoelastic modulator (PEM) 53, and is disposed on the optical path of the laser beam L reflected by the high reflection mirror 47c. The polarizer 51 has the same configuration as in the comparative example and is arranged such that the laser beam L enters as p-polarized light.

[0053] The PEM 53 includes a deep ultraviolet light transmitting element 53a and a piezo element 53b. The deep ultraviolet light transmitting element 53a is an optical element having permeability to deep ultraviolet light with a wavelength of about 193.4 nm or the like, and is formed in a plate shape by, for example, calcium fluoride or synthetic quartz. The deep ultraviolet light transmitting element 53a is disposed on the optical path of the laser beam L that has passed through the polarizer 51.

[0054] The deep ultraviolet light transmitting element 53a has a natural frequency f determined by its material, shape, and size. C In addition, the deep ultraviolet light transmitting element 53a generates stress birefringence in response to an externally applied force. Specifically, the deep ultraviolet light transmitting element 53a generates stress due to an externally applied force, and generates stress birefringence corresponding to this stress. That is, the deep ultraviolet light transmitting element 53a functions as a wave plate that gives a phase difference corresponding to the stress to two orthogonal polarization components of the laser beam L.

[0055] The piezo element 53b is attached to the deep ultraviolet light transmitting element 53a, and applies a periodically changing force to the deep ultraviolet light transmitting element 53a based on a drive signal Dr supplied from the laser processing processor 40. A signal line for the laser processing processor 40 to supply the drive signal Dr to the piezo element 53b is connected between the laser processing processor 40 and the piezo element 53b.

[0056] 3.2 Operation Next, the operation of the laser processing system 1a according to the first embodiment will be described. The operation of the laser processing system 1a is the same as that of the comparative example except for the synchronization control between the laser device 2 and the PEM 53.

[0057] The laser processing processor 40 generates a drive signal Dr whose voltage changes at the natural frequency f C of the deep ultraviolet light transmitting element 53a and supplies it to the piezoelectric element 53b.

[0058] Further, the laser processing processor 40 generates an emission trigger signal Tr having a frequency obtained by dividing the natural frequency f C or the natural frequency f C and transmits it to the laser device 2. That is, the natural frequency f L and the repetition frequency f C satisfy the relationship of f L = f L / k. Here, k is an integer of 1 or more. C

[0059] The laser beam L output from the laser device 2 in response to the emission trigger signal Tr enters the optical device 41 and then enters the optical isolator 50a through the high reflection mirror 47a, the attenuator 48, the high reflection mirror 47b, and the high reflection mirror 47c.

[0060] The laser beam L incident on the optical isolator 50a passes through the polarizer 51 and enters the deep ultraviolet light transmitting element 53a. The deep ultraviolet light transmitting element 53a gives a phase difference corresponding to the stress generated by the force applied from the piezoelectric element 53b to the incident laser beam L and then emits it.

[0061] The laser processing processor 40 synchronizes and controls the laser device 2 and the PEM 53 so that the deep ultraviolet light transmitting element 53a functions as a quarter-wave plate at the timing when the laser beam L passes through the deep ultraviolet light transmitting element 53a. As a result, the optical isolator 50a exhibits the same action as the optical isolator 50 according to the comparative example.

[0062] FIG. 6 shows the timings of various signals related to the synchronization control between the laser device 2 and the PEM 53. The laser processing processor 40 sets the frequency of the master signal as the natural frequency f C and generates a drive signal Dr based on the master signal. For example, the drive signal Dr is a sine wave signal whose voltage changes at a period of 1 / f C . For example, the deep ultraviolet light transmitting element 53a changes its stress at a period of 1 / f C and functions as a quarter-wave plate at the timing when the stress becomes maximum. For example, the natural frequency f C is 48 kHz.

[0063] The laser processing processor 40 generates an emission trigger signal Tr based on the master signal. For example, the laser processing processor 40 generates an emission trigger signal Tr having a repetition frequency f L of 6 kHz with k = 8.

[0064] Note that as shown in FIG. 6 as the passing timing, after the laser processing processor 40 transmits the emission trigger signal Tr to the laser device 2, a certain delay time occurs until the timing when the laser light L passes through the deep ultraviolet light transmitting element 53a. Therefore, the laser processing processor 40 transmits the emission trigger signal Tr at a timing that takes into account the above delay time with respect to the timing when the drive signal Dr becomes maximum, that is, the timing when the deep ultraviolet light transmitting element 53a functions as a quarter-wave plate.

[0065] FIGS. 7 and 8 illustrate the operation of the optical isolator 50a according to the first embodiment. FIG. 7 shows a state where the laser light L is incident on the optical isolator 50a from the upstream side. FIG. 8 shows a state where the return light Lr is incident on the optical isolator 50a from the downstream side.

[0066] As shown in FIG. 7, laser light L of linearly polarized light is incident on the optical isolator 50a from the upstream side. The laser light L incident on the optical isolator 50a is incident on the polarizer 51 as p-polarized light, passes through the polarizer 51, and is incident on the deep ultraviolet light transmitting element 53a. At this time, since the deep ultraviolet light transmitting element 53a functions as a quarter-wave plate, the laser light L is converted into circularly polarized light and emitted from the optical isolator 50a.

[0067] As shown in FIG. 8, the return light Lr of circularly polarized light is incident on the optical isolator 50a from the downstream side. The return light Lr incident on the optical isolator 50a is incident on the deep ultraviolet light transmitting element 53a. At this time, since the deep ultraviolet light transmitting element 53a functions as a quarter-wave plate, the return light Lr is converted into linearly polarized light. The return light Lr emitted from the deep ultraviolet light transmitting element 53a is incident on the polarizer 51 as s-polarized light and is reflected by the polarizer 51. Thereby, the return of the return light Lr to the upstream side of the optical isolator 50a is suppressed.

[0068] 3.3 Effects According to the present embodiment, since the optical isolator 50a is configured using the PEM 53 including the deep ultraviolet light transmitting element 53a, it is possible to realize an optical isolator 50a having higher durability against deep ultraviolet light than the optical isolator 50 according to the comparative example.

[0069] 4. Second Embodiment The laser processing system 1b according to the second embodiment of the present disclosure will be described. Note that the same components as those described above are denoted by the same reference numerals, and redundant descriptions are omitted unless otherwise specified.

[0070] The laser processing system 1a according to the first embodiment performs hole processing by condensing the laser light L on the workpiece 45. On the other hand, the laser processing system 1b according to the second embodiment performs hole processing by projecting an image of the laser light L formed by the photomask 61 onto the workpiece 45.

[0071] 4.1 Configuration FIG. 9 schematically shows the configuration of the laser processing system 1b according to the second embodiment. The laser processing system 1b according to this embodiment differs only in the configuration within the optical device 41 from the first embodiment.

[0072] In this embodiment, an illumination optical system 60, a photomask 61, and a collimating lens 62 are provided on the optical path of the laser beam L between the high reflection mirror 47c and the optical isolator 50a. Further, in this embodiment, a projection optical system 63 is provided on the optical path of the laser beam L between the optical isolator 50a and the window 46, instead of the condensing optical system 49. The illumination optical system 60 is held by a holder 60a. The projection optical system 63 is held by a holder 63a.

[0073] The illumination optical system 60, the photomask 61, and the collimating lens 62 are arranged in this order from the high reflection mirror 47c side. The photomask 61 has holes (not shown) formed therein. Alternatively, the photomask 61 has a transmission region and a shielding region for deep ultraviolet light formed therein. The optical isolator 50a may be arranged on the downstream side of the photomask 61, that is, on the workpiece 45 side, and on the upstream side of the projection optical system 63.

[0074] 4.2 Operation Next, the operation of the laser processing system 1b according to the second embodiment will be described. The operation of the laser processing system 1b is the same as that of the first embodiment except that the optical actions within the optical device 41 are different.

[0075] In this embodiment, the laser beam L reflected by the high-reflection mirror 47c is incident on the illumination optical system 60. The illumination optical system 60 illuminates the incident laser beam L onto the photomask 61. The laser beam L that has passed through the holes or transmission regions formed in the photomask 61 is incident on the optical isolator 50a via the collimating lens 62. The laser beam L incident on the optical isolator 50a passes through the polarizer 51 and the deep ultraviolet light transmission element 53a and is incident on the projection optical system 63. The laser beam L incident on the projection optical system 63 is projected onto the workpiece 45 as an image representing the shape of the holes or transmission regions formed in the photomask 61. The operation of the optical isolator 50a is the same as that in the first embodiment.

[0076] 4.3 Effects According to this embodiment, since the optical isolator 50a is disposed on the downstream side of the photomask 61, the return light Lr is suppressed from being incident on the photomask 61, and damage to the photomask 61 can be suppressed. As a result, the laser processing system 1b has a longer lifespan.

[0077] 5. Modification Examples of Laser Device Next, various modification examples of the laser device 2 will be described. The following modification examples can be applied to both the first embodiment and the second embodiment.

[0078] FIG. 10 schematically shows the configuration of a laser device 2a according to a modification example. The laser device 2a differs from the configuration of the laser device 2 in that a solid-state laser device 70 is used as the master oscillator 21a and an excimer amplifier 21b is used as the power amplifier.

[0079] The solid-state laser device 70 outputs a laser beam L having a wavelength of about 193.4 nm as seed light. The laser beam L output by the solid-state laser device 70 is linearly polarized. The solid-state laser device 70 is arranged such that the laser beam L is incident on the discharge space of the excimer amplifier 21b.

[0080] The excimer amplifier 21b according to this modification example is provided with a convex cylindrical mirror 29a instead of the output coupling mirror 26b, and a concave cylindrical mirror 29b instead of the rear mirror 24b. Other configurations are the same as those of the excimer amplifier 21b shown in FIG. 2.

[0081] The convex cylindrical mirror 29a and the concave cylindrical mirror 29b are arranged such that the laser beam L output from the solid-state laser device 70 is reflected by the convex cylindrical mirror 29a and the concave cylindrical mirror 29b and passes through the discharge space three times. The laser beam L is amplified by passing through the discharge space three times, and the beam is expanded in the discharge direction and output.

[0082] A high-reflection film that highly reflects deep ultraviolet light with a wavelength of about 193.4 nm may be coated on the surfaces of the convex cylindrical mirror 29a and the concave cylindrical mirror 29b.

[0083] The laser processor 20 controls the power supply of the solid-state laser device 70 and each switch of the power supply 23b so that the excimer amplifier 21b discharges and amplifies the laser beam L at the timing when the laser beam L output from the master oscillator 21a passes through the excimer amplifier 21b. Other controls by the laser processor 20 are the same as those in the first embodiment.

[0084] As another modification example of the laser device 2, the laser device 2a may be composed of one solid-state laser device 70. In this case, the excimer amplifier 21b may not be provided, and the solid-state laser device 70 may be arranged such that the laser beam output from the solid-state laser device 70 directly enters the optical device 41.

[0085] 6. Method for manufacturing an electronic device The laser processing method according to each of the above embodiments can be applied to the formation of through holes in the glass substrate included in the interposer 102 in the manufacture of the following electronic device 100.

[0086] FIG. 11 schematically shows the configuration of the electronic device 100. The electronic device 100 shown in FIG. 11 includes an integrated circuit chip 101, an interposer 102, and a circuit board 103. The integrated circuit chip 101 is, for example, a chip-shaped integrated circuit substrate in which an integrated circuit is formed on a silicon substrate. A plurality of bumps 101b electrically connected to the integrated circuit are provided on the integrated circuit chip 101.

[0087] The interposer 102 includes an insulating glass substrate in which a plurality of through holes are formed, and conductors for electrically connecting the front and back surfaces of the glass substrate are provided in the respective through holes. A plurality of lands connected to the bumps 101b provided on the integrated circuit chip 101 are formed on one surface of the interposer 102, and each land is electrically connected to one of the conductors in the through hole. A plurality of bumps 102b are provided on the other surface of the interposer 102, and each bump 102b is electrically connected to one of the conductors in the through hole.

[0088] A plurality of lands connected to the respective bumps 102b are formed on one surface of the circuit board 103. The circuit board 103 also includes a plurality of terminals electrically connected to these lands.

[0089] FIG. 12 shows a manufacturing method of the electronic device 100. As shown in FIG. 12, the manufacturing method of the electronic device 100 in this description includes a first bonding step SP1 and a second bonding step SP2. In the first bonding step SP1, the integrated circuit chip 101 and the interposer 102 are bonded together. Specifically, each bump 101b of the integrated circuit chip 101 is placed on each land of the interposer 102, and the bump 101b and the land are electrically connected. In this way, the integrated circuit chip 101 and the interposer 102 are electrically connected.

[0090] In the second bonding step SP2, the interposer 102 and the circuit board 103 are bonded together. Specifically, each bump 102b of the interposer 102 is placed on each land of the circuit board 103, and the bump 102b and the land are electrically connected. Thus, the integrated circuit chip 101 is electrically connected to the circuit board 103 via the interposer 102. Through the above steps, the electronic device 100 is manufactured.

[0091] 7. Configuration example of a laser processing processor In the present disclosure, the laser processing processor 40 is constituted by, for example, a CPU (Central Processing Unit). The laser processing processor 40 executes the above-described various processes based on a program stored in a memory. Some or all of the functions of the laser processing processor 40 may be realized using an integrated circuit represented by an FPGA (Field Programmable Gate Array) or an ASIC (Application Specific Integrated Circuit).

[0092] Note that the laser processing processor 40 may include the functions of the laser processor 20. That is, the laser processing processor 40 and the laser processor 20 may be constituted by one processor.

[0093] The above description is intended as an illustration and not a limitation. Therefore, it will be apparent to those skilled in the art that various changes can be made to each embodiment of the present disclosure without departing from the scope of the appended claims.

[0094] The terms used throughout this specification and the appended claims should be construed as terms that are "not limiting." For example, the terms "comprising" or "included" should be construed as "not limited to those described as being included." The term "having" should be construed as "not limited to those described as having." Also, the modifier "one" described in this specification and the appended claims should be construed to mean "at least one" or "one or more." Further, the term "at least one of A, B, and C" should be construed as "A," "B," "C," "A + B," "A + C," "B + C," or "A + B + C," and should further be construed to include combinations with things other than "A," "B," and "C."

Claims

1. A laser device that outputs deep ultraviolet laser light in response to reception of a light emission trigger signal, An optical isolator including a polarizer and a deep ultraviolet light transmitting element disposed on the optical path of the laser light, and a piezoelectric element connected to the deep ultraviolet light transmitting element, A processor that supplies a drive signal whose voltage changes at the natural frequency of the deep ultraviolet light transmitting element to the piezoelectric element, and transmits the light emission trigger signal to the laser device using the natural frequency or a frequency obtained by dividing the natural frequency as a repetition frequency so that the deep ultraviolet light transmitting element functions as a quarter-wave plate due to stress birefringence generated in response to the force applied from the piezoelectric element at the timing when the laser light passes through the deep ultraviolet light transmitting element, Comprising A laser processing system that irradiates a workpiece with the laser light emitted from the optical isolator to perform processing.

2. The laser processing system according to claim 1, wherein the laser device includes a master oscillator that outputs the laser light, and an excimer amplifier that amplifies the laser light output by the master oscillator.

3. The laser processing system according to claim 2, wherein the master oscillator is an excimer laser device.

4. The laser processing system according to claim 2, wherein the master oscillator is a solid-state laser device.

5. The laser processing system according to claim 2, wherein the excimer amplifier includes an optical resonator.

6. The laser processing system according to claim 1, including a condensing optical system that condenses the laser light emitted from the optical isolator onto the workpiece.

7. The laser processing system according to claim 1, including a photomask, an illumination optical system disposed on the optical path of the laser light that illuminates the photomask with the laser light, and a projection optical system that projects the laser light that has passed through the photomask onto the workpiece, wherein the optical isolator is disposed on the optical path of the laser light between the photomask and the projection optical system.

8. The laser processing system according to claim 1, wherein the deep ultraviolet light transmitting element is formed of calcium fluoride or synthetic quartz.

9. The laser processing system according to claim 1, wherein the polarizer is an optical element that transmits one of two linearly polarized lights whose polarization directions are orthogonal and reflects the other. ​ ​ The deep ultraviolet light transmission element is disposed on the optical path of the laser light that has passed through the polarizer.

10. A laser device that outputs deep ultraviolet laser light in response to reception of a light emission trigger signal, An optical isolator including a polarizer and a deep ultraviolet light transmission element disposed on the optical path of the laser light, and a piezoelectric element connected to the deep ultraviolet light transmission element, A laser processing method for performing processing by irradiating a workpiece with a laser processing system including the above, A drive signal whose voltage changes at the natural frequency of the deep ultraviolet light transmission element is supplied to the piezoelectric element, and at the timing when the laser light passes through the deep ultraviolet light transmission element, the deep ultraviolet light transmission element functions as a quarter-wave plate due to stress birefringence generated in response to the force applied from the piezoelectric element. Transmitting the light emission trigger signal to the laser device using the natural frequency or a frequency obtained by dividing the natural frequency as a repetition frequency, Irradiating the workpiece with the laser light emitted from the optical isolator to perform processing, A laser processing method including the above.

11. A method for manufacturing an electronic device, A laser device that outputs deep ultraviolet laser light in response to reception of a light emission trigger signal, An optical isolator including a polarizer and a deep ultraviolet light transmission element disposed on the optical path of the laser light, and a piezoelectric element connected to the deep ultraviolet light transmission element, A processor that supplies a drive signal whose voltage changes at the natural frequency of the deep ultraviolet light transmission element to the piezoelectric element, and at the timing when the laser light passes through the deep ultraviolet light transmission element, the deep ultraviolet light transmission element functions as a quarter-wave plate due to stress birefringence generated in response to the force applied from the piezoelectric element. Transmitting the light emission trigger signal to the laser device using the natural frequency or a frequency obtained by dividing the natural frequency as a repetition frequency, Comprising, Forming a plurality of through holes in a glass substrate as the workpiece by a laser processing system that irradiates the workpiece with the laser light emitted from the optical isolator to perform processing, Coupling an interposer having the glass substrate and conductors provided in each of the plurality of through holes, and an integrated circuit chip to electrically connect them to each other, Coupling the interposer and the circuit board to electrically connect them to each other, A method for manufacturing an electronic device including the above.

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