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

Abstract

The invention provides a laser processing system, a laser processing method, and a method for manufacturing an electronic device. A laser processing system according to one aspect of the present disclosure is provided with: 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 an optical path of the laser light, and a piezoelectric element connected to the deep ultraviolet light transmission element; and a processor that supplies a drive signal, the voltage of which changes at the natural frequency of the deep ultraviolet light transmission element, to the piezoelectric element, and transmits a 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, such that the light emission trigger signal is generated at the timing when the laser light passes through the deep ultraviolet light transmission element. The deep ultraviolet light transmitting element functions as a 1 / 4 wavelength plate by stress birefringence generated by a force applied from the piezoelectric element, and the laser beam emitted from the optical isolator is irradiated to the workpiece to process the workpiece.

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, with the miniaturization and high integration of semiconductor integrated circuits, an improvement in resolution has been required. Therefore, a reduction in the wavelength of light emitted from an exposure light source has been promoted. For example, as a gas laser device for exposure, a KrF excimer laser device that emits laser light with an output wavelength of approximately 248.0 nm and an ArF excimer laser device that emits laser light with an output wavelength of approximately 193.4 nm are used.

[0003] In addition, since the pulse width of an excimer laser is approximately several tens of ns and the wavelengths are as short as 248.0 nm and 193.4 nm, respectively, it is sometimes used for direct processing of polymer materials, glass materials, and the like.

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

[0005] In addition, it is known that since materials such as glass and ceramics have a high absorption rate for excimer lasers, even materials that are difficult to process with visible light and infrared lasers can be processed using excimer lasers.

[0006] The spectral linewidth of the spontaneous oscillation light of a KrF excimer laser device and an ArF excimer laser device is as wide as 350 pm to 400 pm. Therefore, if a projection lens is made of a material that transmits ultraviolet light such as KrF and ArF lasers, chromatic aberration may occur. As a result, the resolution may be reduced. Therefore, it is necessary to narrow the spectral linewidth of the laser output from the gas laser device to such an extent that chromatic aberration can be ignored. Therefore, in order to narrow the spectral linewidth, a line narrowing module (LNM: Line Narrowing Module) including a line narrowing element (etalon, grating, etc.) is sometimes provided in the laser resonator of the gas laser device. Hereinafter, a gas laser device whose spectral linewidth has been narrowed will be referred to as a line-narrowed gas laser device.

[0007] Prior Art Documents

[0008] Patent Documents

[0009] Patent Document 1: US Patent No. 9,802,270 Specification

[0010] Patent Document 2: Japanese Unexamined Patent Application Publication No. 2020-60449 Summary of the Invention

[0011] A laser processing system according to one aspect of the present disclosure includes: a laser device that outputs deep ultraviolet laser light upon receiving a light emission trigger signal; an optical isolator that includes 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 a processor that supplies a voltage to the piezoelectric element to generate a drive signal for changing the natural frequency of the deep ultraviolet light transmitting element, and transmits the light emission trigger signal to the laser device at the natural frequency or a frequency obtained by dividing the natural frequency, so that at the timing when the laser light passes through the deep ultraviolet light transmitting element, the deep ultraviolet light transmitting element functions as a quarter-wave plate through stress birefringence, which is generated according to the force applied from the piezoelectric element, and the laser light emitted from the optical isolator is irradiated onto a workpiece to perform processing.

[0012] A laser processing method according to one aspect of the present disclosure performs processing by irradiating a workpiece with a laser processing system, the laser processing system including: a laser device that outputs deep ultraviolet laser light upon receiving a light emission trigger signal; and an optical isolator that includes 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, the laser processing method including the following steps: supplying a voltage to the piezoelectric element to generate a drive signal for changing the natural frequency of the deep ultraviolet light transmitting element, and transmitting the light emission trigger signal to the laser device at the natural frequency or a frequency obtained by dividing the natural frequency, so that at the timing when the laser light passes through the deep ultraviolet light transmitting element, the deep ultraviolet light transmitting element functions as a quarter-wave plate through stress birefringence, which is generated according to the force applied from the piezoelectric element; and irradiating the workpiece with the laser light emitted from the optical isolator to perform processing.

[0013] A manufacturing method of an electronic device according to one aspect of the present disclosure includes the following steps: forming a plurality of through holes on a glass substrate as a workpiece using a laser processing system; bonding an interposer having the glass substrate and conductors respectively disposed in the plurality of through holes to an integrated circuit chip to electrically connect them to each other; and bonding the interposer to a circuit board to electrically connect them to each other. The laser processing system includes: a laser device that outputs deep ultraviolet laser according to the reception of a light emission trigger signal; an optical isolator that includes a polarizer and a deep ultraviolet light transmitting element disposed on the optical path of the laser, and a piezoelectric element connected to the deep ultraviolet light transmitting element; and a processor that supplies a voltage to the piezoelectric element to send a driving signal for changing the natural frequency of the deep ultraviolet light transmitting element, and sends a light emission trigger signal to the laser device at the natural frequency or a frequency obtained by dividing the natural frequency, so that at the timing when the laser passes through the deep ultraviolet light transmitting element, the deep ultraviolet light transmitting element functions as a quarter-wave plate through stress birefringence, and the stress birefringence is generated according to the force applied from the piezoelectric element, and the laser emitted from the optical isolator irradiates the workpiece for processing. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Hereinafter, as an example only, several embodiments of the present disclosure will be described with reference to the drawings.

[0015] Figure 1 is a diagram schematically showing the structure of a laser processing system of a comparative example.

[0016] Figure 2 is a diagram schematically showing the structure of a laser device.

[0017] Figure 3 is a diagram showing a situation where laser enters the optical isolator from the upstream side.

[0018] Figure 4 is a diagram showing a situation where laser enters the optical isolator from the downstream side.

[0019] Figure 5 is a diagram schematically showing the structure of a laser processing system of the first embodiment.

[0020] Figure 6 is a diagram showing the timing of various signals related to the synchronous control of the laser device and the PEM.

[0021] Figure 7 is a diagram showing a situation where laser enters the optical isolator from the upstream side.

[0022] Figure 8 is a diagram showing a situation where laser enters the optical isolator from the downstream side.

[0023] Figure 9This is a diagram schematically showing the structure of the laser processing system according to the second embodiment.

[0024] Figure 10 This is a diagram schematically showing the structure of a modified example of the laser device.

[0025] Figure 11 This is a diagram schematically showing the structure of the electronic device.

[0026] Figure 12 This is a diagram showing the manufacturing method of the electronic device. Detailed Embodiment

[0027] <Content>

[0028] 1. Explanation of Terms

[0029] 1.1 Polarizer

[0030] 1.2 Quarter-Wave Plate

[0031] 2. Comparative Example

[0032] 2.1 Structure

[0033] 2.2 Operation

[0034] 2.3 Problem

[0035] 3. First Embodiment

[0036] 3.1 Structure

[0037] 3.2 Operation

[0038] 3.3 Effect

[0039] 4. Second Embodiment

[0040] 4.1 Structure

[0041] 4.2 Operation

[0042] 4.3 Effect

[0043] 5. Modified Example of Laser Device

[0044] 6. Manufacturing Method of Electronic Device

[0045] 7. Structural Example of Laser Processing Processor

[0046] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. The embodiments described below represent several examples of the present disclosure and do not limit the content of the present disclosure. In addition, the structures and operations described in each embodiment are not necessarily essential as the structures and operations of the present disclosure. Furthermore, the same reference numerals are assigned to the same components, and repeated descriptions are omitted.

[0047] 1. Description of Terms

[0048] 1.1 Polarizer

[0049] 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 an embodiment of the present disclosure is an optical element that transmits one of the two linearly polarized lights with orthogonal polarization directions and reflects the other one.

[0050] 1.2 Quarter-Wave Plate

[0051] In the present disclosure, a quarter-wave plate is an optical element that imparts 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. In addition, the phase difference actually used to make the optical element function as a quarter-wave plate sometimes includes an error of about several degrees based on 90° + n×180°.

[0052] 2. Comparative Example

[0053] 2.1 Structure

[0054] Figure 1 The structure of the laser processing system 1 of the comparative example is schematically shown. In addition, the comparative example is a method known only to the applicant in a way that the applicant recognizes, and is not a publicly known example recognized by the applicant himself.

[0055] The laser processing system 1 includes a laser device 2 and a laser processing device 4 as main structures. The laser processing system 1 is used for laser drilling processing such as forming through holes and the like on a glass substrate for an interlayer.

[0056] The laser device 2 is a laser device that outputs deep ultraviolet pulsed laser. 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 of linearly polarized light with a center wavelength of about 193.4 nm. Hereinafter, the deep ultraviolet pulsed laser output by the laser device 2 will be simply referred to as laser L. In addition, the deep ultraviolet pulsed laser is an example of the "deep ultraviolet laser" of the technology of the present invention. In addition, deep ultraviolet refers to a wavelength band of, for example, 100 nm to 280 nm.

[0057] 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 L between the light exit of the laser device 2 and the light entrance of the laser processing device 4.

[0058] The laser processing device 4 includes a laser processing processor 40, an optical device 41, a frame 42, a moving stage 43, and a workbench 44. The optical device 41 and the moving stage 43 are fixed on the frame 42.

[0059] The table 44 supports a workpiece 45. The workpiece 45 is a processing target to be processed by laser drilling by being irradiated with laser light L. For example, the workpiece 45 is a quartz glass substrate.

[0060] The movable table 43 supports the worktable 44. A workpiece 45 is fixed on the worktable 44. The movable table 43 can move in the X direction, the Y direction, and the Z direction. By adjusting the position of the worktable 44, the position of the workpiece 45 can be adjusted. The X direction, the Y direction, and the Z direction are orthogonal to each other. The X direction and the Y direction are parallel to the surface 45a of the workpiece 45 on which the laser light L is incident. The Z direction is orthogonal to the surface 45a.

[0061] The moving stage 43 adjusts the position of the workpiece 45 under the control of the laser processing processor 40 so that the laser light L emitted from the optical device 41 is irradiated to a desired processing position on the surface 45 a .

[0062] The optical device 41 includes a housing 41a, a window 46, high reflective mirrors 47a, 47b, 47c, an attenuator 48, a focusing optical system 49, and an optical isolator 50. The high reflective mirrors 47a, 47b, 47c, the attenuator 48, the focusing optical system 49, and the optical isolator 50 are arranged inside the housing 41a. The window 46 is located on the optical path between the focusing optical system 49 and the moving stage 43, and is arranged in a hole formed in the housing 41a via an O-ring or the like (not shown).

[0063] The housing 41a is provided with an inlet 41b for sucking nitrogen into the housing 37 and an outlet 41c for discharging nitrogen from the housing 41a to the outside. The inlet 41b is connected to a nitrogen supply source (not shown). The outlet 41c is connected to a discharge device (not shown). The inlet 41b and the outlet 41c are sealed by an O-ring (not shown) to prevent external air from mixing into the housing 41a.

[0064] The high reflective mirrors 47a, 47b, and 47c are fixed to holders (not shown), respectively. The high reflective mirror 47a is arranged to reflect the laser light L that has passed through the optical tube 5, and the reflected laser light L passes through the attenuator 48 and enters the high reflective mirror 47b.

[0065] The attenuator 48 is arranged in the housing 41a on the optical path between the high reflector 47a and the high reflector 47b. The attenuator 48 includes, for example, two partial reflectors 48a and 48b and rotating tables 48c and 48d of the partial reflectors. The partial reflectors 48a and 48b are optical elements whose transmittance changes according to the incident angle of the laser light L. The partial reflectors 48a and 48b adjust the incident angle of the laser light L by rotating tables 48c and 48d.

[0066] The high reflector 47b is configured to reflect the laser beam L that has passed through the attenuator 48, and cause the reflected laser beam L to be incident on the high reflector 47c.

[0067] 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 reflector 47c. For example, the polarizer 51 is a polarization beam splitter that transmits p-polarized light and reflects s-polarized light, and is configured such that the laser beam L is incident as p-polarized light.

[0068] The quarter-wave plate 52 is disposed on the optical path of the laser beam L that has passed through the polarizer 51, and converts the incident laser beam L from linearly polarized light to circularly polarized light and emits it. Specifically, the quarter-wave plate 52 is configured 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°.

[0069] The condensing optical system 49 is fixed to the holder 49a, and is configured to condense the laser beam L emitted from the optical isolator 50 onto the workpiece 45 via the window 46.

[0070] The laser processing controller 40 sends 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 a pulse amount of the laser beam L, and is generated based on a main signal having a prescribed frequency. The laser processing controller 40 is an example of the "controller" of the technology of the present disclosure.

[0071] Figure 2 The structure of the laser device 2 is schematically shown. The laser device 2 includes a laser controller 20, a master oscillator 21a, and an excimer amplifier 21b. In this comparative example, the excimer amplifier 21b is set as a power oscillator that serves as an oscillation amplifier.

[0072] The master oscillator 21a is an excimer laser device that includes 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 sealed therein. Further, in the chamber 25a, a pair of windows 28a are provided at positions where the laser beam L passes through. The pair of windows 28a are configured 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.

[0073] The power supply 23a is a pulse power supply module, and is connected to the charger 22a. 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 in the range of 40% to 60%.

[0074] 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. A pair of discharge electrodes 27b are provided in the chamber 25b, and the above-mentioned laser gas is sealed. In addition, a pair of windows 28b are provided in the chamber 25b at the position where the laser light L passes. The pair of windows 28b is configured so that the incident angle of the laser light L becomes the Brewster angle. The rear mirror 24b and the output coupling mirror 26b constitute an optical resonator.

[0075] The power source 23b is a pulse power module, and is connected to the charger 22b. The rear mirror 24b is a partial reflection mirror having a reflectivity of the laser light L in the range of 50% to 90%.

[0076] The laser processor 20 controls the charger 22a and power supply 23a of the master oscillator 21a and the charger 22b and power supply 23b of the excimer amplifier 21b. Specifically, the laser processor 20 sets charging voltages for the chargers 22a and 22b and controls the on / off of switches included in the power supplies 23a and 23b.

[0077] 2.2 Action

[0078] Next, the operation of the comparative example laser processing system 1 is 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 light L focused by the focusing optical system 49 is inside the workpiece 45 and at a predetermined depth from the surface 45a.

[0079] 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 energy density of the laser light L irradiated onto the surface 45 a of the workpiece 45 reaches the target value.

[0080] Next, the laser processing processor 40 performs the laser processing at a predetermined repetition frequency f L A light emission trigger signal Tr having a predetermined number of pulses is sent to the laser device 2 .

[0081] When receiving the light emission trigger signal Tr, the laser processor 20 sets the charging voltage corresponding to the target pulse energy Et for the chargers 22a and 22b. In addition, the laser processor 20 controls the switches of the power supplies 23a and 23b so that the excimer amplifier 21b discharges and amplifies the laser light L at the timing when the laser light L generated by the discharge in the main oscillator 21a passes through the excimer amplifier 21b.

[0082] As a result, the laser beam L is output from the laser device 2 in synchronization with the light emission trigger signal Tr and is incident on the optical device 41 of the laser processing device 4. The laser beam L incident on the optical device 41 is reflected by the high reflector 47a and is incident on the attenuator 48. The laser beam L incident on the attenuator 48 passes through the partial reflectors 48a and 48b and is incident on the high reflector 47b.

[0083] The laser beam L reflected by the high reflector 47b is reflected by the high reflector 47c and is incident on the optical isolator 50. The laser beam L incident on the optical isolator 50 passes through the polarizer 51 and the quarter-wave plate 52 and is incident on the condensing optical system 49. The laser beam L incident on the condensing optical system 49 is condensed through the window 46 at a depth specified from the surface 45a inside the workpiece 45.

[0084] By repeatedly irradiating the workpiece 45 with the laser beam L, the workpiece 45 is drilled. In addition, 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 to the optical device 41 as the return light Lr through the window 46, thereby damaging the optical elements inside the optical device 41. The optical isolator 50 has the effect of suppressing the return light Lr from returning to the upstream side inside the optical device 41.

[0085] Figure 3 and Figure 4 The operation of the optical isolator 50 of the comparative example will be described. Figure 3 This shows the case where the laser beam L is incident on the optical isolator 50 from the upstream side. Figure 4 This shows the case where the return light Lr is incident on the optical isolator 50 from the downstream side.

[0086] As Figure 3 shown, the linearly polarized laser beam L is incident on the optical isolator 50 from the upstream side. The laser beam L incident on the optical isolator 50 is incident on the polarizer 51 as p-polarized light, and thus passes through the polarizer 51 and is incident on the quarter-wave plate 52. The laser beam 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 is emitted from the optical isolator 50.

[0087] As Figure 4 shown, the circularly polarized return light Lr 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 is 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 beam L incident on the quarter-wave plate 52 from the upstream side. Therefore, the return light Lr is incident on the polarizer 51 as s-polarized light and is reflected by the polarizer 51. Thereby, the return light Lr is suppressed from returning to the upstream side of the optical isolator 50.

[0088] 2.3 Problems

[0089] Next, the problems of the laser processing system 1 of the comparative example will be described. As described above, the optical isolator 50 used in the laser processing system 1 of 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. 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 L. Therefore, it is an issue to achieve an optical isolator with high durability against deep ultraviolet light.

[0090] 3. First Embodiment

[0091] The laser processing system 1a of the first embodiment of the present disclosure will be described. In addition, the same reference numerals are given to the structures that are the same as those described above, and redundant descriptions are omitted unless otherwise specified.

[0092] 3.1 Structure

[0093] Figure 5 The structure of the laser processing system 1a of the first embodiment is schematically shown. The difference between the structure of the laser processing system 1a and that of the laser processing system 1 of the comparative example is only that the optical isolator 50a is used instead of the optical isolator 50 of the comparative example.

[0094] The optical isolator 50a includes a polarizer 51 and a photoelastic modulator (PEM) 53, and is disposed on the optical path of the laser L reflected by the high reflector 47c. The polarizer 51 has the same structure as that of the comparative example, and is arranged so that the laser L is incident as p-polarized light.

[0095] The PEM 53 includes a deep ultraviolet light transmitting element 53a and a piezoelectric element 53b. The deep ultraviolet light transmitting element 53a is an optical element having transmissivity for deep ultraviolet light with a wavelength of about 193.4 nm or the like, and is formed in a plate shape of calcium fluoride or synthetic quartz, for example. The deep ultraviolet light transmitting element 53a is disposed on the optical path of the laser L that has passed through the polarizer 51.

[0096] 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 according to the force applied from the outside. Specifically, the deep ultraviolet light transmitting element 53a generates stress due to the force applied from the outside, and generates stress birefringence corresponding to the stress. That is, the deep ultraviolet light transmitting element 53a functions as a wavelength plate that gives a phase difference corresponding to the stress to two orthogonal polarization components of the laser L.

[0097] The piezoelectric element 53b is mounted on the deep ultraviolet light transmitting element 53a, and based on the drive signal Dr supplied from the laser processing processor 40, a periodically varying force is applied to the deep ultraviolet light transmitting element 53a. A signal line for the laser processing processor 40 to supply the drive signal Dr to the piezoelectric element 53b is connected between the laser processing processor 40 and the piezoelectric element 53b.

[0098] 3.2 Operation

[0099] Next, the operation of the laser processing system 1a of 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 performing the synchronization control of the laser device 2 and the PEM 53.

[0100] The laser processing processor 40 generates a drive signal Dr whose voltage varies at the natural frequency f of the deep ultraviolet light transmitting element 53a and supplies it to the piezoelectric element 53b. C and supplies it to the piezoelectric element 53b.

[0101] In addition, the laser processing processor 40 generates a light emission trigger signal Tr having a frequency that is the natural frequency f C or a frequency obtained by dividing the natural frequency f C by a frequency divider as the repetition frequency f L and sends it to the laser device 2. That is, the natural frequency f C and the repetition frequency f L satisfy the relationship f L = f C / k. Here, k is an integer of 1 or more.

[0102] The laser L output from the laser device 2 according to the light emission trigger signal Tr, after being incident on the optical device 41, is incident on the optical isolator 50a via the high reflector 47a, the attenuator 48, the high reflector 47b, and the high reflector 47c.

[0103] The laser L incident on the optical isolator 50a passes through the polarizer 51 and is incident on the deep ultraviolet light transmitting element 53a. The deep ultraviolet light transmitting element 53a imparts a phase difference corresponding to the stress generated by the force applied from the piezoelectric element 53b to the incident laser L and emits it.

[0104] The laser processing processor 40 performs synchronization control of 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 L passes through the deep ultraviolet light transmitting element 53a. Thus, the optical isolator 50a serves the same role as the optical isolator 50 of the comparative example.

[0105] Figure 6 shows the timing of various signals related to the synchronization control of the laser device 2 and the PEM 53. The laser processing processor 40 sets the frequency of the main signal to the natural frequency f C, a drive signal Dr is generated based on the main signal. For example, the drive signal Dr is a sine wave signal with a voltage varying periodically at 1 / f C The stress varies periodically at 1 / f C At the timing when the stress becomes maximum, the deep ultraviolet light transmitting element 53a functions as a quarter-wave plate. For example, the natural frequency f C is 48 kHz.

[0106] The laser processing processor 40 generates a light emission trigger signal Tr based on the main signal. For example, assuming k = 8, the laser processing processor 40 generates a light emission trigger signal Tr having a repetition frequency f of 6 kHz L of.

[0107] In addition, as Figure 6 shown as the passing timing, after the laser processing processor 40 sends the light emission trigger signal Tr to the laser device 2, a certain delay time is generated until the timing when the laser L passes through the deep ultraviolet light transmitting element 53a. Therefore, the laser processing processor 40 estimates the above delay time at the timing when the drive signal Dr becomes maximum, that is, at the timing when the deep ultraviolet light transmitting element 53a functions as a quarter-wave plate, and sends the light emission trigger signal Tr.

[0108] Figure 7 and Figure 8 explain the operation of the optical isolator 50a of the first embodiment. Figure 7 It shows the case where the laser L is incident on the optical isolator 50a from the upstream side. Figure 8 It shows the case where the return light Lr is incident on the optical isolator 50a from the downstream side.

[0109] As Figure 7 shown, the linearly polarized laser L is incident on the optical isolator 50a from the upstream side. The laser L incident on the optical isolator 50a is incident on the polarizer 51 as p-polarized light, and thus 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 L is converted into circularly polarized light and emitted from the optical isolator 50a.

[0110] As Figure 8 shown, the circularly polarized return light Lr 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.

[0111] 3.3 Effect

[0112] According to this embodiment, the optical isolator 50a is configured using the PEM53 including the deep ultraviolet light transmitting element 53a. Therefore, it is possible to achieve an optical isolator 50a with higher durability for deep ultraviolet light compared to the optical isolator 50 of the comparative example.

[0113] 4. Second Embodiment

[0114] The laser processing system 1b of the second embodiment of the present disclosure will be described. In addition, the same reference numerals are given to the structures that are the same as those described above, and redundant descriptions are omitted except in special cases.

[0115] The laser processing system 1a of the first embodiment performs drilling by condensing the laser L on the workpiece 45. In contrast, the laser processing system 1b of the second embodiment performs drilling by projecting an image of the laser L formed by the photomask 61 onto the workpiece 45.

[0116] 4.1 Structure

[0117] Figure 9 The structure of the laser processing system 1b of the second embodiment is schematically shown. The structure of the laser processing system 1b of this embodiment is different from that of the first embodiment only in the structure within the optical device 41.

[0118] 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 L between the high reflector 47c and the optical isolator 50a. In addition, in this embodiment, a projection optical system 63 is provided on the optical path of the laser 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.

[0119] The illumination optical system 60, the photomask 61, and the collimating lens 62 are arranged in order from the high reflector 47c side. A hole (not shown) is formed in the photomask 61. Alternatively, a transmission region and a shielding region for deep ultraviolet light are formed in the photomask 61. The optical isolator 50a only needs to be arranged at a position downstream of the photomask 61, that is, on the workpiece 45 side and upstream of the projection optical system 63.

[0120] 4.2 Operation

[0121] Next, the operation of the laser processing system 1b of the second embodiment will be described. The operation of the laser processing system 1b is the same as that of the first embodiment except for the optical action within the optical device 41.

[0122] In this embodiment, the laser beam L reflected by the high reflector 47c is incident on the illumination optical system 60. The illumination optical system 60 irradiates the incident laser beam L onto the photomask 61. The laser beam L that has passed through the holes or transmissive 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 transmissive 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 transmissive regions formed in the photomask 61. The function of the optical isolator 50a is the same as that in the first embodiment.

[0123] 4.3 Effects

[0124] According to this embodiment, since the optical isolator 50a is disposed on the downstream side of the photomask 61, it is possible to suppress the return light Lr from being incident on the photomask 61, and it is possible to suppress damage to the photomask 61. As a result, the laser processing system 1b has a longer service life.

[0125] 5. Modification Examples of the Laser Device

[0126] 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.

[0127] Figure 10 The structure of the modified laser device 2a is schematically shown. The difference in the structure between the laser device 2a and the laser device 2 is 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.

[0128] 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 from the solid-state laser device 70 is linearly polarized light. 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.

[0129] In this modification example, the excimer amplifier 21b is provided with a convex cylindrical mirror 29a instead of the output coupling mirror 26b, and a concave cylindrical mirror 29b is provided instead of the rear mirror 24b. The other structures are the same as those of the Figure 2 excimer amplifier 21b shown.

[0130] 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 light beam is amplified in the discharge direction and output.

[0131] A high-reflection film that highly reflects deep ultraviolet light with a wavelength of approximately 193.4 nm may also be coated on the surfaces of the convex cylindrical lens 29a and the concave cylindrical lens 29b.

[0132] The laser processor 20 controls the power supply of the solid laser device 70 and each switch of the power supply 23b such that the excimer amplifier 21b discharges and amplifies the laser L at the timing when the laser L output from the master oscillator 21a passes through the excimer amplifier 21b. Other controls of the laser processor 20 are the same as those in the first embodiment.

[0133] As another modification example of the laser device 2, the laser device 2a may also be constituted by one solid laser device 70. In this case, the excimer amplifier 21b is not provided, and the solid laser device 70 is arranged such that the laser output from the solid laser device 70 directly enters the optical device 41.

[0134] 6. Method for manufacturing an electronic device

[0135] In the manufacturing of the following electronic device 100, the laser processing method of each of the above embodiments can be applied to form through holes in the glass substrate included in the interposer 102.

[0136] Figure 11 Schematically shows the structure of the electronic device 100. Figure 11 The shown electronic device 100 has 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 on 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.

[0137] The interposer 102 includes an insulating glass substrate in which a plurality of through holes are formed, and a conductor that electrically connects the front and back surfaces of the glass substrate is provided in each through hole. A plurality of pads connected to the bumps 101b provided on the integrated circuit chip 101 are formed on one surface of the interposer 102, and each pad is electrically connected to any one of the conductors in the through holes. A plurality of bumps 102b are provided on the other surface of the interposer 102, and each bump 102b is electrically connected to any one of the conductors in the through holes.

[0138] On one surface of the circuit board 103, a plurality of pads connected to the respective bumps 102b are formed. In addition, the circuit board 103 includes a plurality of terminals electrically connected to these pads.

[0139] Figure 12 Shows the manufacturing method of the electronic device 100. As Figure 12As shown, the manufacturing method of the electronic device 100 in this description includes a first bonding process SP1 and a second bonding process SP2. In the first bonding process SP1, the integrated circuit chip 101 is bonded to the interposer 102. Specifically, the respective bumps 101b of the integrated circuit chip 101 are disposed on the respective pads of the interposer 102, and the bumps 101b and the pads are electrically connected. In this way, the integrated circuit chip 101 and the interposer 102 are electrically connected.

[0140] In the second bonding process SP2, the interposer 102 is bonded to the circuit board 103. Specifically, the respective bumps 102b of the interposer 102 are disposed on the respective pads of the circuit board 103, and the bumps 102b and the pads are electrically connected. In this way, the integrated circuit chip 101 is electrically connected to the circuit board 103 via the interposer 102. Through the above processes, the electronic device 100 is manufactured.

[0141] 7. Structural example of a laser processing processor

[0142] 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 various processes based on a program stored in a memory. Part or all of the functions of the laser processing processor 40 can also be implemented using an integrated circuit represented by an FPGA (Field Programmable Gate Array) or an ASIC (Application Specific Integrated Circuit).

[0143] In addition, the laser processing processor 40 may also 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.

[0144] The above description is for illustrative purposes only and not for limitation. Therefore, it is obvious to those skilled in the art that various embodiments of the present disclosure can be modified without departing from the appended claims.

[0145] The terms used in this specification and the appended claims should be construed as "non-limiting" terms. For example, the term "comprising" or "including" should be construed as "not limited to being described as including". The term "having" should be construed as "not limited to being described as having". Additionally, the phrase "a" described in this specification and the appended claims should be construed as "at least one" or "one or more". Furthermore, 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 also be construed as including combinations thereof with elements other than "A", "B", and "C".

Claims

1. A laser processing system comprising: A laser device that outputs deep ultraviolet laser light in response to receipt of a light emission trigger signal; an optical isolator including a polarizer and a deep ultraviolet light transmitting element arranged on an optical path of the laser, and a piezoelectric element connected to the deep ultraviolet light transmitting element; and a processor that supplies a driving signal whose voltage varies with the natural frequency of the deep ultraviolet light transmitting element to the piezoelectric element, and sends 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 when the laser passes through the deep ultraviolet light transmitting element, the deep ultraviolet light transmitting element functions as a 1 / 4 wavelength plate by stress birefringence, and the stress birefringence is generated according to the force applied from the piezoelectric element, The laser light emitted from the optical isolator is irradiated onto a workpiece to perform processing.

2. The laser processing system according to claim 1, wherein: The laser device comprises: a master oscillator that outputs the laser light; and An excimer amplifier amplifies the laser light outputted from 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, wherein: The laser processing system includes a focusing optical system that focuses the laser light emitted from the optical isolator onto the workpiece.

7. The laser processing system according to claim 1, wherein: The laser processing system comprises: Photomask; an illumination optical system disposed on an optical path of the laser light and illuminating the photomask with the laser light; and a projection optical system that projects the laser light that has passed through the photomask toward the workpiece, The optical isolator is arranged on an 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 having orthogonal polarization directions and reflects the other. The deep ultraviolet light transmitting element is arranged on an optical path of the laser light that has transmitted through the polarizer.

10. A laser processing method, comprising: irradiating a workpiece with a laser processing system to perform processing; The laser processing system comprises: a laser device that outputs deep ultraviolet laser light in response to receiving a light emission trigger signal; and an optical isolator that includes a polarizer and a deep ultraviolet light transmitting element disposed on an optical path of the laser light, and a piezoelectric element connected to the deep ultraviolet light transmitting element. The laser processing method comprises the following steps: Supplying a driving signal whose voltage varies with the natural frequency of the deep ultraviolet light transmitting element to the piezoelectric element, and sending 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 when the laser passes through the deep ultraviolet light transmitting element, the deep ultraviolet light transmitting element functions as a quarter wavelength plate by stress birefringence, and the stress birefringence is generated according to the force applied from the piezoelectric element; The laser light emitted from the optical isolator is irradiated onto a workpiece to perform processing.

11. A method for manufacturing an electronic device, comprising the following steps: A plurality of through holes are formed on a glass substrate as a workpiece using a laser processing system; combining an interposer having the glass substrate and the conductors respectively disposed in the plurality of through holes with an integrated circuit chip so as to be electrically connected to each other; and The interposer is combined with the circuit substrate to be electrically connected to each other, The laser processing system comprises: A laser device that outputs deep ultraviolet laser light in response to receipt of a light emission trigger signal; an optical isolator including a polarizer and a deep ultraviolet light transmitting element arranged on an optical path of the laser, and a piezoelectric element connected to the deep ultraviolet light transmitting element; and a processor that supplies a driving signal whose voltage varies with the natural frequency of the deep ultraviolet light transmitting element to the piezoelectric element, and sends 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 when the laser passes through the deep ultraviolet light transmitting element, the deep ultraviolet light transmitting element functions as a 1 / 4 wavelength plate by stress birefringence, and the stress birefringence is generated according to the force applied from the piezoelectric element, The laser light emitted from the optical isolator is irradiated onto the workpiece to perform processing.

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