Laser beam machining apparatus, laser beam machining system, and method for manufacturing electronic device

Abstract

To provide a laser beam machining apparatus that performs hole machining by irradiating a workpiece with laser beam output from a laser beam device.SOLUTION: A laser beam machining apparatus comprises: a first optical slit which is disposed at a first position on an optical path of laser beam and has an opening extending in a second direction orthogonal to a first direction; a second optical slit which is disposed at a second position different from the first position on the optical path of the laser beam and has an opening extending in the first direction; an illumination optical system which includes a first condensing optical system that condenses the laser beam in the first direction into a first line shape and irradiates the first optical slit with the laser beam, and a second condensing optical system that condenses the laser beam in the second direction into a second line shape and irradiates the second optical slit with the laser beam; and a projection optical system which images, on the surface of the workpiece, the laser beam having passed through the first optical slit and the second optical slit so as to represent the shape of an overlapping portion between the opening of the first optical slit and the opening of the second optical slit.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present disclosure relates to a laser processing apparatus, a laser processing system, 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, improvement in resolution has been demanded. For this reason, shortening of the wavelength of light emitted from an exposure light source has been promoted. For example, as a gas laser apparatus for exposure, a KrF excimer laser apparatus that outputs laser light with a wavelength of about 248.0 nm and an ArF excimer laser apparatus 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 by excimer laser light is possible, and it is known that the processed shape becomes beautiful.

[0005] Further, since glass, ceramics, and the like 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 linewidths of the spontaneous emission light of KrF excimer laser devices and ArF excimer laser devices are 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) 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 narrowband gas laser device.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Patent Document 6

[0008] A laser processing apparatus according to one aspect of the present disclosure is a laser processing apparatus that performs hole processing by irradiating a workpiece with laser light output from a laser device, including: a first optical slit disposed at a first position on the optical path of the laser light and having an opening extending in a second direction orthogonal to the first direction; a second optical slit disposed at a second position different from the first position on the optical path of the laser light and having an opening extending in the first direction; a first condensing optical system that condenses the laser light in the first direction to form a first line shape and irradiates the first optical slit; a second condensing optical system that condenses the laser light in the second direction to form a second line shape and irradiates the second optical slit; an illumination optical system including the first condensing optical system and the second condensing optical system; and a projection optical system that forms an image of the laser light transmitted through the first optical slit and the second optical slit on the surface of the workpiece so as to represent the shape of an overlapping portion between the opening of the first optical slit and the opening of the second optical slit.

[0009] A laser processing system according to one aspect of the present disclosure is a laser processing system that performs hole processing by irradiating a workpiece with laser light output from a laser device, including: a laser device that outputs laser light; a first optical slit disposed at a first position on the optical path of the laser light and having an opening extending in a second direction orthogonal to the first direction; a second optical slit disposed at a second position different from the first position on the optical path of the laser light and having an opening extending in the first direction; a first condensing optical system that condenses the laser light in the first direction to form a first line shape and irradiates the first optical slit; a second condensing optical system that condenses the laser light in the second direction to form a second line shape and irradiates the second optical slit; an illumination optical system including the first condensing optical system and the second condensing optical system; and a projection optical system that forms an image of the laser light transmitted through the first optical slit and the second optical slit on the surface of the workpiece so as to represent the shape of an overlapping portion between the opening of the first optical slit and the opening of the second optical slit.

[0010] A method for manufacturing an electronic device according to one aspect of the present disclosure is a method for manufacturing an electronic device. The method includes a laser processing apparatus that performs hole processing by irradiating a workpiece with laser light output from a laser device. The laser processing apparatus includes a first optical slit disposed at a first position on the optical path of the laser light and having an opening extending in a second direction orthogonal to a first direction, a second optical slit disposed at a second position different from the first position on the optical path of the laser light and having an opening extending in the first direction, a first condensing optical system that condenses the laser light in the first direction to form a first line shape and irradiates the first optical slit, a second condensing optical system that condenses the laser light in the second direction to form a second line shape and irradiates the second optical slit, an illumination optical system including the first condensing optical system and the second condensing optical system, and a projection optical system that forms an image of the laser light transmitted through the first optical slit and the second optical slit on the surface of the workpiece so as to represent the shape of an overlapping portion between the opening of the first optical slit and the opening of the second optical slit. The method includes forming a plurality of through holes in a glass substrate as a workpiece by the laser processing apparatus, coupling an interposer having the glass substrate and conductors provided in each of the plurality of through holes to an integrated circuit chip and electrically connecting them to each other, and coupling the interposer to a circuit board and electrically connecting 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 Diffractive Optical Element 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. Modified Examples of the First Embodiment 4.1 First Modified Example 4.1.1 Configuration 4.1.2 Operation 4.1.3 Effect 4.2 Second Modification Example 4.2.1 Configuration 4.2.2 Operation 4.2.3 Effect 4.3 Third Modification Example 4.3.1 Configuration 4.3.2 Operation 4.3.3 Effect 4.4 Other Modification Examples 5. Second Embodiment 5.1 Configuration 5.2 Operation 5.3 Effect 6. Modification Examples of the Second Embodiment 6.1 First Modification Example 6.1.1 Configuration 6.1.2 Operation 6.1.3 Effect 6.2 Second Modification Example 6.2.1 Configuration 6.2.2 Operation 6.2.3 Effect 7. Modification Examples of the Laser Device 8. Beam Expander 9. Optical Axis Monitor 10. Modification Examples of the Optical Device 11. Method for Manufacturing an Electronic Device 12. Configuration Example of a 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 Diffractive Optical Element A diffractive optical element (DOE) is an optical element that utilizes the diffraction phenomenon of light. For example, a DOE is fabricated by processing a fine structure designed by simulation onto a substrate using microfabrication technology. A DOE can convert laser light into various patterns. In the present disclosure, laser light is converted into a multi-point pattern by a DOE.

[0015] 2. Comparative Example 2.1 Configuration FIG. 1 schematically shows the configuration of a laser processing system 1 according to a 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.

[0016] 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 hole processing such as forming holes such as via holes in a glass substrate for an interposer.

[0017] The laser device 2 is a laser device that outputs ultraviolet pulsed laser light. For example, the laser device 2 is a discharge-excited laser device that outputs ultraviolet pulsed laser light using F2, ArF, KrF, XeCl, XeF, etc. as a laser medium. In the present disclosure, the laser device 2 is a KrF excimer laser device that outputs ultraviolet pulsed laser light with a central wavelength of 248.0 nm. Hereinafter, the ultraviolet pulsed laser light output by the laser device 2 is simply referred to as laser light Lb.

[0018] The laser device 2 and the laser processing device 4 are connected by an optical path tube 5. The optical path tube 5 is disposed on the optical path of the laser light Lb between the exit of the laser device 2 and the entrance of the laser processing device 4.

[0019] In the present disclosure, the traveling direction of the laser beam Lb output from the laser device 2 is referred to as the Z direction, the direction orthogonal to the Z direction and corresponding to the discharge direction in the laser device 2 is referred to as the V direction, and the direction orthogonal to both the Z direction and the V direction is referred to as the H direction. In the optical device 41, the traveling direction of the laser beam Lb changes by being reflected by a high-reflection mirror described later. In the optical device 41, the traveling direction of the laser beam Lb emitted from the illumination optical system 50 described later is defined as the Z direction. Also, in the optical device 41, the V direction is orthogonal to the Z direction and is a direction corresponding to the discharge direction relatively. The V direction corresponds to the "first direction" according to the technology of the present disclosure. The H direction corresponds to the "second direction" according to the technology of the present disclosure.

[0020] The laser processing apparatus 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 for which hole processing is to be performed. The workpiece 45 is a glass substrate for an interposer, for example, a non-alkali glass substrate. Note that the workpiece 45 may be a substrate formed of quartz glass, an organic material, a single-crystal silicon, ceramics, or the like. In this comparative example, a hole 45b is formed in the workpiece 45.

[0022] The moving stage 43 supports the table 44. The workpiece 45 is fixed on the table 44. The moving stage 43 enables the table 44 to move in the V direction, the H direction, and the Z direction, and changes the position of the workpiece 45 by moving the table 44. The V direction and the H direction are parallel to the surface 45a of the workpiece 45. The Z direction is orthogonal to the surface 45a.

[0023] The optical device 41 includes a housing 41a, high-reflection mirrors 46a and 46b, an attenuator 47, an illumination optical system 50, a mask 48, and a projection optical system 60. Each component within the optical device 41 is fixed to a holder (not shown) and is arranged at a predetermined position within the housing 41a.

[0024] The high-reflection mirror 46a is arranged to reflect the laser beam Lb that has passed through the optical path tube 5, such that the reflected laser beam Lb is incident on the high-reflection mirror 46b. The optical path tube 5 and the housing 41a are purged, for example, with a purge gas. The purge gas is, for example, nitrogen gas, an inert gas, or the like, and is a gas that hardly absorbs the laser beam Lb.

[0025] The attenuator 47 is arranged within the housing 41a on the optical path of the laser beam Lb reflected by the high-reflection mirror 46b. The attenuator 47 includes, for example, two partial reflection mirrors 47a and 47b, and rotation stages 47c and 47d for these partial reflection mirrors. The partial reflection mirrors 47a and 47b are optical elements whose transmittance changes depending on the incident angle of the laser beam Lb. The incident angles of the laser beam Lb for the partial reflection mirrors 47a and 47b are respectively adjusted by the rotation stages 47c and 47d.

[0026] The illumination optical system 50 includes a beam expander 51, a high-reflection mirror 52, and a condensing optical system 57. The beam expander 51 is arranged on the optical path of the laser beam Lb that has passed through the attenuator 47, and is arranged to expand the beam diameter of the incident laser beam Lb at the same magnification in the V direction and the H direction and then emit it. In this comparative example, the beam expander 51 has a fixed magnification.

[0027] The high-reflection mirror 52 is arranged to reflect the laser beam Lb emitted from the beam expander 51, such that the reflected laser beam Lb is incident on the condensing optical system 57. The condensing optical system 57 is, for example, a convex lens having a spherical surface.

[0028] The mask 48 is disposed at the rear focal position of the condensing optical system 57. A single circular aperture 48a is formed in the mask 48, and the laser beam Lb condensed by the condensing optical system 57 is illuminated thereon. Further, the mask 48 is arranged such that the laser beam Lb passing through the aperture 48a is imaged on the surface 45a of the workpiece 45 at a predetermined projection magnification by the projection optical system 60. Note that the aperture 48a is not limited to a physical through-hole and may be a transmission region that transmits the laser beam Lb.

[0029] The projection optical system 60 includes a collimating optical system 66, a diaphragm 63, and an imaging optical system 64. The collimating optical system 66 is, for example, a convex lens having a spherical surface, and is arranged such that the position of the mask 48 becomes the front focal position.

[0030] The diaphragm 63 is disposed on the optical path of the laser beam Lb collimated by the collimating optical system 66. For example, a square aperture 63a is formed so as to have a predetermined numerical aperture.

[0031] The imaging optical system 64 is, for example, a convex lens having a spherical surface, and is arranged such that an image of the laser beam Lb representing the shape of the aperture 48a of the mask 48 is formed at the rear focal position.

[0032] The laser processing processor 40 is capable of transmitting the target pulse energy Et and the emission trigger signal Tr to the laser device 2, and is configured to be able to transmit and receive other signals to and from the laser device 2. The target pulse energy Et is the target value of the pulse energy of the laser beam Lb. The emission trigger signal Tr is a trigger signal for causing the laser device 2 to output one pulse of the laser beam Lb.

[0033] Further, the laser processing processor 40 is a control device that controls the laser device 2 and the moving stage 43 such that the laser beam Lb is irradiated at each step position in a step-and-repeat manner to a processing area that requires hole processing on the surface 45a of the workpiece 45. The laser processing processor 40 is an example of the "processor" according to the technology of the present disclosure.

[0034] Figure 2 schematically shows the configuration of the laser device 2. The laser device 2 includes an oscillator 20, a monitor module 30, a shutter 35, and a laser processor 38. The oscillator 20 includes a chamber 21, an optical resonator composed of a rear mirror 25a and an output coupling mirror (OC) 25b, a charger 23, and a PPM (Pulsed Power Module) 22. The optical resonator of this comparative example is a Fabry-Perot resonator.

[0035] Windows 21a and 21b are provided in the chamber 21. A laser gas as a laser medium is enclosed in the chamber 21.

[0036] Also, an opening is formed in the chamber 21, and an electrical insulating plate 26 in which a plurality of feed-throughs 26a are embedded is provided so as to close this opening. The PPM 22 is disposed on the electrical insulating plate 26. In the chamber 21, a pair of discharge electrodes 27a and 27b as main electrodes and a ground plate 28 are disposed. The shape of the discharge surfaces of the discharge electrodes 27a and 27b is rectangular.

[0037] The discharge electrodes 27a and 27b are arranged such that their discharge surfaces face each other in order to excite the laser medium by discharge. One surface of the discharge electrode 27a on the side opposite to the discharge surface is supported by the electrical insulating plate 26. The discharge electrode 27a is connected to the feed-through 26a. One surface of the discharge electrode 27b on the side opposite to the discharge surface is supported by the ground plate 28.

[0038] The PPM 22 includes a switch 22a, a charging capacitor (not shown), a pulse transformer, a magnetic compression circuit, and a peaking capacitor. The peaking capacitor is connected to the feed-through 26a via a connection part (not shown). The charger 23 charges the charging capacitor based on control from the laser processor 38.

[0039] Switch 22a is controlled to be turned on / off by laser processor 38. Laser processor 38 turns on switch 22a in response to the emission trigger signal Tr transmitted from laser processing processor 40.

[0040] When switch 22a is turned on, current flows from the charging capacitor to the primary side of the pulse transformer, and a reverse current flows through the secondary side of the pulse transformer by electromagnetic induction. The magnetic compression circuit is connected to the secondary side of the pulse transformer and compresses the pulse width of the current pulse. The peaking capacitor is charged by this current pulse. When the voltage of the peaking capacitor reaches the breakdown voltage of the laser gas, dielectric breakdown occurs in the laser gas between discharge electrodes 27a and 27b, and a discharge occurs. One pulse of laser light Lb is generated by this discharge.

[0041] Rear mirror 25a is formed by coating a highly reflective film on a planar substrate. Output coupling mirror 25b is formed by coating a partial reflection film on a planar substrate. Chamber 21 is disposed between rear mirror 25a and output coupling mirror 25b. The laser light Lb generated in chamber 21 is amplified by the optical resonator and output from output coupling mirror 25b.

[0042] Monitor module 30 includes beam splitter 31, condenser lens 32, and optical sensor 33. Beam splitter 31 is disposed on the optical path of laser light Lb output from output coupling mirror 25b and reflects a part of laser light Lb. Condenser lens 32 is disposed on the optical path of laser light Lb reflected by beam splitter 31, condenses laser light Lb, and makes it incident on optical sensor 33. Optical sensor 33 measures the pulse energy of laser light Lb and transmits the measured value to laser processor 38.

[0043] Laser processor 38 controls the pulse energy of laser light Lb output from laser device 2 to be the target pulse energy Et by changing the charging voltage of charger 23 based on the measured value of the pulse energy by optical sensor 33.

[0044] The shutter 35 is disposed on the optical path of the laser beam Lb that passes through the beam splitter 31. The shutter 35 opens and closes in response to a command from the laser processor 38. The laser processor 38 controls the output of the laser beam Lb from the laser device 2 by controlling the shutter 35.

[0045] FIG. 3 schematically shows the beam shape of the laser beam Lb cut along the A-A line shown in FIG. 2 in the VH plane. The beam shape is a rectangular shape that is longer in the V direction than in the H direction.

[0046] 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 so that the rear focal position of the imaging optical system 64 coincides with the surface 45a of the workpiece 45.

[0047] Next, the laser processing processor 40 transmits the target pulse energy Et to the laser device 2 and controls the transmittance Ta of the attenuator 47 so that the fluence of the laser beam Lb irradiated on the surface 45a of the workpiece 45 becomes the target fluence Ft. Here, the fluence refers to the energy density of the laser beam Lb irradiated at a certain position. The target fluence Ft is the fluence optimal for processing that exceeds the ablation threshold at the surface 45a of the workpiece 45.

[0048] The target fluence Ft is expressed by the relational expression Ft = Et × Ta × To / S. Here, To is the transmittance of the entire optical system other than the attenuator 47 in the optical device 41. Assuming that the transmittances of the high reflection mirrors 46a and 46b are T1, the transmittance of the illumination optical system 50 is T2, the transmittance of the mask 48 is T3, and the transmittance of the projection optical system 60 is T4, the relationship To = T1 × T2 × T3 × T4 is satisfied. S is the irradiation area of the laser beam Lb on the surface 45a. The irradiation area S is expressed by the relational expression S = π(D / 2) 2 . D is the beam spot diameter of the laser beam Lb.

[0049] When the laser processor 38 receives the target pulse energy Et, it closes the shutter 35 and sets the charging voltage corresponding to the target pulse energy Et in the charger 23. The laser processor 38 inputs a trigger to the switch 22a of the PPM 22 in response to an internal trigger (not shown). As a result, the oscillator 20 oscillates naturally.

[0050] The laser beam Lb output from the oscillator 20 is sampled by the monitor module 30 and the pulse energy is measured. The laser processor 38 controls the charging voltage of the charger 23 so that the difference ΔE between the measured value of the pulse energy and the target pulse energy Et approaches zero.

[0051] When the difference ΔE is within the allowable range, the laser processor 38 transmits a permission signal to the laser processing processor 40 to open the shutter 35. When receiving the permission signal, the laser processing processor 40 transmits a light emission trigger signal Tr of a predetermined number of pulses N at a predetermined repetition frequency f to the laser device 2. As a result, in synchronization with the light emission trigger signal Tr, the laser beam Lb transmitted through the beam splitter 31 of the monitor module 30 enters the optical device 41 of the laser processing device 4.

[0052] The laser beam Lb incident on the optical device 41 passes through the attenuator 47 via the high reflection mirrors 46a and 46b and enters the illumination optical system 50. The laser beam Lb incident on the illumination optical system 50 has its beam diameter expanded by the beam expander 51. The laser beam Lb with the expanded beam diameter is reflected by the high reflection mirror 52 and condensed by the condenser optical system 57 to illuminate the mask 48.

[0053] The laser beam Lb transmitted through the mask 48 enters the projection optical system 60. The laser beam Lb incident on the projection optical system 60 is collimated by the collimating optical system 66 and enters the aperture 63. The laser beam Lb passing through the aperture 63a of the aperture 63 is imaged on the surface 45a of the workpiece 45 by the imaging optical system 64 to form an image representing the shape of the aperture 48a.

[0054] By repeatedly irradiating the workpiece 45 with the laser beam Lb, ablation occurs on the workpiece 45 and drilling is performed.

[0055] 2.3 Problems Next, the problems of the laser processing apparatus 4 according to the comparative example will be described. FIG. 4 schematically shows the shape of the laser beam Lb irradiated onto the mask 48. The laser beam Lb is irradiated so as to cover the aperture 48a.

[0056] The laser processing apparatus 4 condenses the laser beam Lb and irradiates the mask 48 in order to increase the utilization efficiency of the laser beam Lb incident from the laser apparatus 2, so that the fluence Fm on the mask 48 becomes high. When the fluence Fm is high, the periphery of the aperture 48a that shields the laser beam Lb may be damaged and the shape of the aperture 48a may be distorted, so that the image formed on the surface 45a of the workpiece 45 may be deformed. By condensing the laser beam Lb and irradiating the mask 48 in this way, the pulse life of the mask 48 is reduced.

[0057] For example, when drilling a workpiece 45 made of glass or ceramics, it is necessary to set the target fluence Ft high, so the fluence Fm approaches the damage threshold, and the pulse life of the mask 48 may be further reduced. For example, the damage threshold is 1 J / cm 2 is.

[0058] The fluence Fm is expressed by the relational expression Fm = Ft × Mg 2 / T4. Here, Mg is the projection magnification of the projection optical system 60. For example, when Ft = 25 J / cm 2 , Mg = 1 / 5, and T4 = 90%, the fluence Fm is 1.1 J / cm 2 and exceeds the damage threshold.

[0059] Therefore, in the present disclosure, a laser processing apparatus with a long pulse life of the mask is provided.

[0060] 3. First Embodiment The laser processing system 1 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.

[0061] 3.1 Configuration FIG. 5 schematically shows the configuration of the laser processing system 1 according to the first embodiment. The laser processing system 1 differs from the laser processing system 1 according to the comparative example only in the configuration of the optical device 41.

[0062] In the present embodiment, the illumination optical system 50 includes a first condenser optical system 53 and a second condenser optical system 54 instead of the condenser optical system 57. The first condenser optical system 53 and the second condenser optical system 54 are sequentially arranged on the optical path of the laser beam Lb reflected by the high-reflection mirror 52. Note that the arrangement order of the first condenser optical system 53 and the second condenser optical system 54 may be reversed.

[0063] The first condenser optical system 53 and the second condenser optical system 54 are cylindrical convex lenses having optical power only in one direction. The first condenser optical system 53 has optical power in the V direction and condenses the laser beam Lb in the V direction so as to have a line shape extending in the H direction at the beam waist position of the laser beam Lb in the V direction. The second condenser optical system 54 has optical power in the H direction and condenses the laser beam Lb in the H direction so as to have a line shape extending in the V direction at the beam waist position of the laser beam Lb in the H direction.

[0064] Hereinafter, the beam waist position in the V direction is referred to as the "first beam waist position", and the beam waist position in the H direction is referred to as the "second beam waist position". Also, the line shape extending in the H direction is referred to as the "first line shape", and the line shape extending in the V direction is referred to as the "second line shape". The first beam waist position is an example of the "first position" according to the technology of the present disclosure. The second beam waist position is an example of the "second position" according to the technology of the present disclosure.

[0065] In this embodiment, instead of the mask 48, a first optical slit 71 and a second optical slit 72 are arranged on the optical path of the laser beam Lb output from the illumination optical system 50. The first optical slit 71 has a rectangular opening 71a extending in the H direction. The second optical slit 72 has a rectangular opening 72a extending in the V direction.

[0066] In this embodiment, the first optical slit 71 is arranged at the first beam waist position, and the second optical slit 72 is arranged at the second beam waist position. The opening 71a of the first optical slit 71 is illuminated by the first line-shaped laser beam Lb. The opening 72a of the second optical slit 72 is illuminated by the second line-shaped laser beam Lb. Note that the openings 71a and 72a are not limited to physical through holes, and may be transmission regions that transmit the laser beam Lb.

[0067] In this embodiment, the projection optical system 60 includes a first collimating optical system 61 and a second collimating optical system 62 instead of the collimating optical system 66. The first collimating optical system 61 and the second collimating optical system 62 are cylindrical convex lenses having optical power only in one direction. The first collimating optical system 61 has optical power in the V direction and collimates the laser beam Lb transmitted through the first optical slit 71 in the V direction. The second collimating optical system 62 has optical power in the H direction and collimates the laser beam Lb transmitted through the second optical slit 72 in the H direction.

[0068] The first collimating optical system 61 is arranged such that the first optical slit 71 is located at the front focal position. The second collimating optical system 62 is arranged such that the second optical slit 72 is located at the front focal position. It is preferable that the focal length Fcv of the first collimating optical system 61 is equal to the focal length Fch of the second collimating optical system 62.

[0069] FIG. 6 shows the first beam waist position P1 and the second beam waist position P2. FIG. 7 schematically shows the beam shape of the laser beam Lb cut along the B-B line shown in FIG. 6 on the VH plane. FIG. 8 schematically shows the beam shape of the laser beam Lb cut along the C-C line shown in FIG. 6 on the VH plane. That is, FIG. 7 shows the light intensity distribution of the laser beam Lb of the first line shape at the first beam waist position P1, and FIG. 8 shows the light intensity distribution of the laser beam Lb of the second line shape at the second beam waist position P2.

[0070] In FIG. 7, Wwv indicates the total beam waist width in the V direction. The total beam waist width Wwv is the beam width at which the light intensity becomes 1 / e 2 times the maximum value at the first beam waist position P1. In FIG. 8, Wwh indicates the total beam waist width in the H direction. The total beam waist width Wwh is the beam width at which the light intensity becomes 1 / e 2 times the maximum value at the second beam waist position P2.

[0071] The beam waist position does not necessarily coincide with the rear focal position of the condensing optical system. Since the laser device 2 is a discharge excitation type, the first beam waist position P1 is downstream of the rear focal position of the first condensing optical system 53, and the second beam waist position P2 may be downstream of the rear focal position of the second condensing optical system 54. In particular, since the second beam waist position P2 is downstream of the rear focal position of the second condensing optical system 54, it is preferable to arrange the second condensing optical system 54 upstream of the position separated upstream by the focal length of the second condensing optical system 54 from the second beam waist position P2.

[0072] FIG. 9 schematically shows the configuration of the first optical slit 71. The first optical slit 71 includes a pair of blades 73a, 73b. The aperture 71a is formed by a pair of blades 73a, 73b spaced apart in the V direction. The material of the blades 73a, 73b is preferably, for example, high melting point metals such as tungsten (W), molybdenum (Mo), or tantalum (Ta), and may also be diamond, diamond-like carbon, or the like.

[0073] Assuming that the width of the opening 71a in the V direction is Wvs, the relationship Wvs < Wwv is satisfied. The laser beam Lb is illuminated on the first optical slit 71 so as to cover the opening 71a in the V direction. Hereinafter, the width Wvs is referred to as the "first slit width Wvs".

[0074] FIG. 10 schematically shows the configuration of the second optical slit 72. The second optical slit 72 includes a pair of blades 74a and 74b. The opening 72a is formed by a pair of blades 74a and 74b spaced apart in the H direction. The material of the blades 74a and 74b is preferably, for example, tungsten, molybdenum, or tantalum, which are high melting point metals, and may also be diamond, diamond-like carbon, or the like.

[0075] Assuming that the width of the opening 72a in the H direction is Whs, the relationship Whs < Wwh is satisfied. The laser beam Lb is illuminated on the second optical slit 72 so as to cover the opening 72a in the H direction. Hereinafter, the width Whs is referred to as the "second slit width Whs".

[0076] 3.2 Operation Next, the operation of the laser processing system 1 according to the first embodiment will be described. The operation of the laser processing system 1 according to the present embodiment differs only in the action within the optical device 41 from the comparative example. Hereinafter, only the points different from the comparative example will be described.

[0077] The laser beam Lb incident on the illumination optical system 50 has its beam diameter expanded by the beam expander 51. The laser beam Lb with the expanded beam diameter is reflected by the high reflection mirror 52, enters the first condensing optical system 53, passes through the first condensing optical system 53, and enters the second condensing optical system 54. The laser beam Lb is condensed into a first line shape by the first condensing optical system 53 and illuminated on the first optical slit 71. Also, the laser beam Lb is condensed into a second line shape by the second condensing optical system 54 and illuminated on the second optical slit 72.

[0078] The laser beam Lb that has passed through the first optical slit 71 and the second optical slit 72 is incident on the projection optical system 60. The laser beam Lb incident on the projection optical system 60 is collimated in the V direction by the first collimating optical system 61, collimated in the H direction by the second collimating optical system 62, and then incident on the aperture 63. The laser beam Lb that has passed through the aperture 63a of the aperture 63 is imaged on the surface 45a of the workpiece 45 by the imaging optical system 64.

[0079] As shown in FIG. 11, a rectangular image of the laser beam Lb representing the shape of the overlapping portion of the aperture 71a of the first optical slit 71 and the aperture 72a of the second optical slit 72 is imaged on the surface 45a of the workpiece 45. By repeatedly irradiating the workpiece 45 with the laser beam Lb, ablation occurs on the workpiece 45 and drilling is performed.

[0080] 3.3 Effects In this embodiment, the first line-shaped laser beam Lb condensed in the V direction by the first condensing optical system 53 illuminates the first optical slit 71, and the second line-shaped laser beam Lb condensed in the H direction by the second condensing optical system 54 illuminates the second optical slit 72. Therefore, the fluence of the laser beam Lb illuminating each of the first optical slit 71 and the second optical slit 72 is reduced compared to the fluence of the laser beam Lb irradiated on the mask 48 in the comparative example. As a result, damage to the first optical slit 71 and the second optical slit 72 is suppressed, and a laser processing apparatus 4 with a long pulse lifetime can be provided.

[0081] Also, in this embodiment, since the first optical slit 71 is arranged at the first beam waist position P1 and the second optical slit 72 is arranged at the second beam waist position P2, the laser beam Lb can be efficiently transmitted.

[0082] 4. Modifications of the First Embodiment Next, various modifications of the first embodiment will be described.

[0083] 4.1 First Modification In the first modification example, only the configurations of the illumination optical system 50 and the projection optical system 60 are different from those of the first embodiment.

[0084] 4.1.1 Configuration FIG. 12 partially shows the configurations of the illumination optical system 50 and the projection optical system 60 according to the first modification example. FIG. 12 shows the configuration as viewed from the H direction and the configuration as viewed from the V direction.

[0085] In this modification example, the first condensing optical system 53 is a combined lens formed by combining a cylindrical convex lens 53a and a cylindrical concave lens 53b. The cylindrical convex lens 53a and the cylindrical concave lens 53b have optical power in the V direction and condense the laser beam Lb in the V direction so as to form a first line shape.

[0086] Also, in this modification example, the second condensing optical system 54 is a combined lens formed by combining a cylindrical convex lens 54a and a cylindrical concave lens 54b. The cylindrical convex lens 54a and the cylindrical concave lens 54b have optical power in the H direction and condense the laser beam Lb in the H direction so as to form a second line shape.

[0087] Also, an actuator 55 is provided in the second condensing optical system 54 to make it possible to change the interval between the cylindrical convex lens 54a and the cylindrical concave lens 54b. For example, the actuator 55 is a one-axis moving stage. The actuator 55 is controlled by the laser processing processor 40. In this modification example, the actuator 55 moves the cylindrical convex lens 54a. Note that the actuator 55 may move the cylindrical concave lens 54b.

[0088] Also, in this modification example, the first collimating optical system 61 is a combined lens formed by combining a cylindrical concave lens 61a and a cylindrical convex lens 61b. The cylindrical concave lens 61a and the cylindrical convex lens 61b have optical power in the V direction and collimate the laser beam Lb that has passed through the first optical slit 71 in the V direction.

[0089] In addition, in this modified example, the second collimating optical system 62 is a combined lens formed by combining a cylindrical concave lens 62a and a cylindrical convex lens 62b. The cylindrical concave lens 62a and the cylindrical convex lens 62b have optical power in the H direction, and collimate the laser beam Lb transmitted through the second optical slit 72 in the H direction.

[0090] 4.1.2 Operation Since the operation of the laser processing system 1 according to this modified example is the same as that of the first embodiment, the description of the operation is omitted.

[0091] 4.1.3 Effects In this modified example, since the illumination optical system 50 and the projection optical system 60 are configured by a plurality of combined lenses, the distance from the illumination optical system 50 to the workpiece 45 can be shortened. This is advantageous when using an illumination optical system 50 with a small numerical aperture.

[0092] Table 1 shows a specification example of the illumination optical system 50 and the projection optical system 60 for performing high aspect ratio hole processing on a glass substrate for an interposer.

[0093]

Table 1

[0094] In Table 1, fi is the focal length of the imaging optical system 64, NAi is the numerical aperture of the imaging optical system 64, Mg is the projection magnification of the projection optical system 60, and NAo is the numerical aperture of the first collimating optical system 61 and the second collimating optical system 62. Also, fo is the focal length of the first collimating optical system 61 and the second collimating optical system 62, and NAil is the numerical aperture of the first condensing optical system 53 and the second condensing optical system 54. Here, the relationship NAil = NAi × Mg is satisfied.

[0095] As shown in Table 1, the numerical aperture NAi is in the range of 0.03 to 0.06, the projection magnification Mg is in the range of 1 / 30 to 1 / 10, and the numerical apertures NAo and NAil are each in the range of 0.001 to 0.004. Thus, since the numerical apertures NAo and NAil are very small and the focal length fo is 1000 mm or more, usually, the distance from the illumination optical system 50 to the workpiece 45 is several meters or more. In this modified example, even when the numerical aperture is small, by using a plurality of lens sets, the distance from the illumination optical system 50 to the workpiece 45 can be shortened.

[0096] Note that in this modified example, before the hole machining operation, the laser processing processor 40 controls the actuator 55 to change the distance between the cylindrical convex lens 54a and the cylindrical concave lens 54b, thereby adjusting the second beam waist position P2. This is because, as described above, the second beam waist position P2 is downstream of the rear focal position of the second condensing optical system 54.

[0097] 4.2 Second Modified Example The second modified example differs from the first embodiment only in that an optical axis stabilization system for stabilizing the optical axis of the laser beam Lb to the illumination optical system 50 is added in the optical device 41.

[0098] 4.2.1 Configuration FIG. 13 schematically shows the configuration of the laser processing system 1 according to the second modified example. The optical axis stabilization system includes a beam steering device 80 for adjusting the optical axis and an optical axis monitor 81 for monitoring the optical axis.

[0099] The beam steering device 80 includes actuators 82a, 82b attached to the high reflection mirror 46a, actuators 83a, 83b attached to the high reflection mirror 46b, and a driver 84. The actuators 82a, 82b change the attitude of the high reflection mirror 46a around two axes orthogonal to each other. The actuators 83a, 83b change the attitude of the high reflection mirror 46b around two axes orthogonal to each other. The driver 84 drives the actuators 82a, 82b and the actuators 83a, 83b based on an instruction from the laser processing processor 40.

[0100] A beam splitter 85 is disposed on the optical path of the laser beam Lb between the beam steering device 80 and the illumination optical system 50. The beam splitter 85 reflects a part of the laser beam Lb output from the beam steering device 80 and makes it incident on the optical axis monitor 81. The optical axis monitor 81 measures the position of the optical axis based on the laser beam Lb incident from the beam splitter 85.

[0101] 4.2.2 Operation The operation of the laser processing system 1 according to this modification is the same as that of the first embodiment except that the optical axis stabilization operation is performed during the hole processing operation.

[0102] Before the hole processing operation, the laser processing processor 40 measures and stores in advance the target position of the optical axis through which the laser beam Lb passes through the first optical slit 71 and the second optical slit 72 with a high transmittance. During the hole processing operation, the laser processing processor 40 acquires the measured value of the position of the optical axis from the optical axis monitor 81, and controls the driver 84 to change the attitudes of the high reflection mirrors 46a, 46b so that the measured value approaches the target position.

[0103] 4.2.3 Effects In this modification, by performing the optical axis stabilization operation during the hole processing operation, the transmittance of the laser beam Lb passing through the first optical slit 71 and the second optical slit 72 can be maintained at a high value. As a result, the fluence and imaging state of the laser beam Lb on the surface 45a of the workpiece 45 are stabilized, and a high-quality hole 45b can be processed.

[0104] 4.3 Third Modified Example In the third modified example, only the configuration of the projection optical system 60 is different from that of the first embodiment.

[0105] 4.3.1 Configuration FIG. 14 schematically shows the configuration of the laser processing system 1 according to the third modified example. In this modified example, a DOE 65 is disposed on the optical path of the laser beam Lb between the aperture 63 and the imaging optical system 64 in the projection optical system 60.

[0106] 4.3.2 Operation The operation of the laser processing system 1 according to this modified example is different from that of the first embodiment only in the action of the projection optical system 60. In this modified example, the laser beam Lb that has passed through the aperture 63a of the aperture 63 is incident on the DOE 65. The DOE 65 divides the incident laser beam Lb into a plurality of beams with different angles and makes them incident on the imaging optical system 64.

[0107] The imaging optical system 64 forms a plurality of images of each beam representing the shape of the overlapping portion between the aperture 71a of the first optical slit 71 and the aperture 72a of the second optical slit 72, that is, a multi-point pattern, on the surface 45a of the workpiece 45. By repeatedly irradiating the workpiece 45 with the laser beam Lb divided into a plurality of beams, ablation occurs on the workpiece 45 and a plurality of holes 45b are simultaneously processed.

[0108] 4.3.3 Effects In this modified example, by using the DOE 65, a plurality of holes 45b can be simultaneously processed in the workpiece 45.

[0109] In addition, when using DOE65, it is necessary to increase the fluence on the surface 45a of the workpiece 45 in order to split the laser beam Lb. Therefore, when DOE65 is used in the comparative example, the fluence on the mask 48 becomes high, and the mask 48 can be easily damaged. In this modified example, as described in the first embodiment, since the fluence of the laser beam Lb irradiated to each of the first optical slit 71 and the second optical slit 72 is reduced, damage is suppressed. Therefore, in this modified example, DOE65 can be used while optimally maintaining the fluence on the surface 45a of the workpiece 45.

[0110] In this modified example, DOE65 is an optical element separate from the imaging optical system 64. However, DOE65 may be an optical element including the function of the imaging optical system 64. That is, DOE65 may split the laser beam Lb that has passed through the aperture 63 into a plurality of beams and form an image of the plurality of beams on the surface 45a of the workpiece 45. In this case, the imaging optical system 64 may not be arranged.

[0111] 4.4 Other Modified Examples In the first embodiment, the image formed on the surface 45a of the workpiece 45 has a rectangular shape, which is the shape of the overlapping portion of the aperture 71a of the first optical slit 71 and the aperture 72a of the second optical slit 72. However, it is preferable to make the shape of this image closer to a circular shape. There are the following three modes for making the shape of the image closer to a circular shape.

[0112] The first mode is a method of adjusting the resolution of the imaging optical system 64. Let the resolution of the imaging optical system 64 be R, then the relationship R = λ / (2×NAi) is satisfied. Here, λ is the wavelength of the laser beam Lb. According to this relational expression, the resolution R depends on the numerical aperture NAi. For example, by making the size of the aperture 63a of the aperture 63 variable, the numerical aperture NAi can be changed to adjust the resolution R. By making the resolution R approximately the same as the diameter of the hole 45b to be processed, the shape of the image can be made closer to a circular shape.

[0113] When the resolution R is smaller than the diameter of the hole 45b to be machined, the image becomes angular and approaches a rectangular shape. In this case, by using the second or third aspect, the shape of the image can be made to approach a circular shape. In the second aspect, the shape of the aperture 63a of the diaphragm 63 is changed. In the third aspect, the shapes of the aperture 71a of the first optical slit 71 and the aperture 72a of the second optical slit 72 are changed.

[0114] FIG. 15 schematically shows the shape of the aperture 63a of the diaphragm 63 that enables the shape of the image to approach a circular shape. The aperture 63a is in the shape of a pincushion that is symmetric with respect to the V direction and the H direction. The aperture 63a is narrower closer to the central part with respect to the V direction and the H direction. Thus, by using the diaphragm 63 having the pincushion-shaped aperture 63a, the image can be corrected so as to approach a circular shape.

[0115] FIG. 16 schematically shows the shape of the aperture 71a of the first optical slit 71 that enables the shape of the image to approach a circular shape. FIG. 17 schematically shows the shape of the aperture 72a of the second optical slit 72 that enables the shape of the image to approach a circular shape. The apertures 71a and 72a are each in the shape of a barrel that is symmetric with respect to the V direction and the H direction. The aperture 71a is wider closer to the central part with respect to the H direction. The aperture 72a is wider closer to the central part with respect to the V direction. By using the first optical slit 71 having the barrel-shaped aperture 71a and the second optical slit 72 having the barrel-shaped aperture 72a, the image can be corrected so as to approach a circular shape.

[0116] By using any of the above aspects, the shape of the machined hole 45b can be made to approach a circular shape. Note that any of the above aspects may be applied to the third modification example described above. In this case, a plurality of circular holes 45b can be machined simultaneously.

[0117] 5. Second Embodiment The laser processing system 1 according to the second embodiment of the present disclosure will be described. The components similar to those described above are denoted by the same reference numerals, and redundant descriptions will be omitted unless otherwise specified.

[0118] 5.1 Configuration FIG. 18 schematically shows the configuration of the laser processing system 1 according to the second embodiment. The laser processing system 1 differs from the laser processing system 1 according to the first embodiment only in the configuration of the optical device 41.

[0119] In the present embodiment, the first optical slit 71 has a variable first slit width Wvs and is controlled by the laser processing processor 40. Also, in the present embodiment, the second optical slit 72 has a variable second slit width Whs and is controlled by the laser processing processor 40.

[0120] Further, in the present embodiment, the laser processing processor 40 is provided with an interface for communicating with the external device 6. The laser processing processor 40 receives data necessary for hole processing from the external device 6. This data includes the target value Dt of the diameter of the hole 45b to be processed, the material of the workpiece 45, and the like. The external device 6 may be a management system for managing the laser processing device 4 and the like, an input device for inputting processing condition data for hole processing, or the like.

[0121] 5.2 Operation The operation of the laser processing system 1 according to the present embodiment differs from that of the first embodiment only in that it includes an adjustment operation for adjusting the first slit width Wvs and the second slit width Whs before performing hole processing.

[0122] FIG. 19 shows the flow of the hole processing operation according to the second embodiment. The description of the operations similar to those in the first embodiment will be omitted.

[0123] First, the laser processing processor 40 acquires a target value Dt from an external device 6 (step S10). Next, the laser processing processor 40 calculates a set value W (step S11). For example, the laser processing processor 40 calculates the set value W based on the relational expression W = Dt / Mg.

[0124] Next, the laser processing processor 40 controls the first optical slit 71 and the second optical slit 72 so that the first slit width Wvs and the second slit width Whs become the set value W (step S12). Then, the laser processing processor 40 transmits a light emission trigger signal Tr for the number of pulses required for hole processing to the laser device 2 (step S13). As a result, the laser light Lb with a beam diameter of the target value Dt is irradiated onto the workpiece 45, and hole processing is performed.

[0125] 5.3 Effects In the comparative example, it is necessary to replace the mask 48 to change the diameter of the hole 45b to be processed, and since alignment needs to be performed again when the mask 48 is replaced, the throughput decreases. In the present embodiment, without replacing the first optical slit 71 and the second optical slit 72, the first slit width Wvs and the second slit width Whs are adjusted according to the target value Dt of the diameter of the hole 45b to be processed, so a decrease in throughput can be suppressed.

[0126] Note that the beam spot diameter irradiated on the surface 45a of the workpiece 45 may not match the diameter of the actually formed hole 45b. In this case, the laser processing processor 40 may store a correction coefficient k in advance and calculate the set value W based on the relational expression W = k × Dt / Mg. The correction coefficient k can be obtained by dividing the target value Dt by the diameter of the actually formed hole 45b.

[0127] Also, the above-described DOE 65 may be arranged between the aperture 63 and the imaging optical system 64. In this case, a plurality of holes 45b can be processed simultaneously.

[0128] 6. Modifications of the Second Embodiment Next, various modifications of the second embodiment will be described.

[0129] 6.1 First modification In the first modification, only the configuration of the illumination optical system 50 is different from that of the second embodiment.

[0130] 6.1.1 Configuration FIG. 20 schematically shows the configuration of the laser processing system 1 according to the first modification. In this modification, the illumination optical system 50 includes an actuator 56a that moves the first condensing optical system 53 in the optical axis direction, and an actuator 56b that moves the second condensing optical system 54 in the optical axis direction. For example, the actuators 56a and 56b are one-axis moving stages. The actuators 56a and 56b are controlled by the laser processing processor 40. The actuator 56a is an example of the "first actuator" according to the technology of the present disclosure. The actuator 56b is an example of the "second actuator" according to the technology of the present disclosure.

[0131] 6.1.2 Operation FIG. 21 shows the flow of the hole processing operation according to the first modification. The hole processing operation according to this modification is different from the hole processing operation according to the second embodiment only in that steps S20 to S23 are added between step S12 and step S13.

[0132] In this modification, after step S12, the laser processing processor 40 determines whether the full width Wwv of the beam waist in the V direction is smaller than the set value W (step S20). When Wwv≧W (step S20: NO), the laser processing processor 40 transfers the process to step S22.

[0133] When Wwv < W (step S20: YES), the laser processing processor 40 controls the actuator 56a to move the first condenser optical system 53 in the optical axis direction, thereby shifting the first beam waist position P1 from the position of the first optical slit 71 (step S21). Specifically, defocusing is performed so that the beam spot diameter in the V direction of the laser beam Lb illuminated on the first optical slit 71 becomes larger than the set value W. The laser processing processor 40 preferably moves the first condenser optical system 53 upstream so that the first beam waist position P1 is upstream of the position of the first optical slit 71.

[0134] Next, the laser processing processor 40 determines whether the total beam waist width Wwh in the H direction is smaller than the set value W (step S22). When Wwh ≥ W (step S22: NO), the laser processing processor 40 shifts the process to step S13.

[0135] When Wwh < W (step S22: YES), the laser processing processor 40 controls the actuator 56b to move the second condenser optical system 54 in the optical axis direction, thereby shifting the second beam waist position P2 from the position of the second optical slit 72 (step S23). Specifically, defocusing is performed so that the beam spot diameter in the H direction of the laser beam Lb illuminated on the second optical slit 72 becomes larger than the set value W. The laser processing processor 40 preferably moves the second condenser optical system 54 upstream so that the second beam waist position P2 is upstream of the position of the second optical slit 72.

[0136] 6.1.3 Effect In the second embodiment, the diameter of the hole 45b to be processed cannot be made larger than the value determined by the total beam waist width. In this modification, by shifting the beam waist position and defocusing, the diameter of the hole 45b to be processed can be made larger than the value determined by the total beam waist width.

[0137] Note that the laser processing processor 40 may previously store the full widths Wwv and Wwh of the beam waist used in the determinations of steps S20 and S22. Alternatively, the laser processing processor 40 may calculate the full widths Wwv and Wwh of the beam waist used in the determinations of steps S20 and S22 using the following formulas (1) and (2). Wwv=(2 / π)×(λ / NAv)×Mv 2 ···(1) Wwh=(2 / π)×(λ / NAh)×Mh 2 ···(2)

[0138] Here, NAv is the numerical aperture of the first condenser optical system 53, and Mv 2 is the M square value in the V direction. Also, NAh is the numerical aperture of the second condenser optical system 54, and Mh 2 is the M square value in the H direction. The M square values Mv 2 , Mh 2 may be pre-measured measurement values.

[0139] Also, as shown in FIG. 22, similar to the first modification of the first embodiment, the first condenser optical system 53 and the second condenser optical system 54 may each be an achromatic doublet. Although not shown in FIG. 22, the first collimating optical system 61 and the second collimating optical system 62 may each be an achromatic doublet. In this case, for example, it is preferable to provide the actuator 56a on the cylindrical convex lens 53a and the actuator 56b on the cylindrical convex lens 54a.

[0140] The laser processing processor 40 moves the first beam waist position P1 by controlling the actuator 56a to move the cylindrical convex lens 53a in the optical axis direction. Also, the laser processing processor 40 moves the second beam waist position P2 by controlling the actuator 56b to move the cylindrical convex lens 54a in the optical axis direction.

[0141] 6.2 Second Modification The second modification is different from the second embodiment only in the configuration of the illumination optical system 50.

[0142] 6.2.1 Configuration FIG. 23 schematically shows the configuration of the laser processing system 1 according to the second modification example. In this modification example, the beam expander 51 has a variable magnification. The magnification of the beam expander 51 is controlled by the laser processing processor 40.

[0143] 6.2.2 Operation FIG. 24 shows the flow of the hole processing operation according to the second modification example. The hole processing operation according to this modification example is different from the hole processing operation according to the second embodiment only in that steps S30 to S32 are added between step S12 and step S13.

[0144] In this modification example, after step S12, the laser processing processor 40 determines whether the total beam waist width Wwv in the V direction is smaller than the set value W (step S30). When Wwv < W (step S30: YES), the laser processing processor 40 transfers the process to step S32.

[0145] When Wwv ≥ W (step S30: NO), the laser processing processor 40 determines whether the total beam waist width Wwh in the H direction is smaller than the set value W (step S31). When Wwh ≥ W (step S31: NO), the laser processing processor 40 transfers the process to step S13.

[0146] When Wwh < W (step S31: YES), the laser processing processor 40 controls the magnification of the beam expander 51 so that Wwv ≥ W and Wwh ≥ W (step S32). The numerical apertures NAv and NAh change depending on the magnification of the beam expander 51. Therefore, according to the above formulas (1) and (2), it can be seen that the total beam waist widths Wwv and Wwh can be changed by controlling the magnification of the beam expander 51.

[0147] 6.2.3 Effects In this modification example, by controlling the magnification of the beam expander 51 to increase the overall beam waist width, the diameter of the hole 45b to be machined can be made larger than the value determined by the initial overall beam waist width.

[0148] Note that the laser processing processor 40 may store in advance the overall beam waist widths Wwv and Wwh used in the determinations of steps S30 and S31. Further, the laser processing processor 40 may calculate the overall beam waist widths Wwv and Wwh used in the determinations of steps S30 and S31 using the above equations (1) and (2).

[0149] Since the numerical apertures NAv and NAh change depending on the magnification of the beam expander 51, the laser processing processor 40 can calculate the overall beam waist widths Wwv and Wwh after changing the magnification of the beam expander 51 using the above equations (1) and (2). Specifically, the overall beam waist widths Wwv and Wwh can be calculated by substituting the numerical apertures NAv and NAh corresponding to the magnification of the beam expander 51 into the above equations (1) and (2).

[0150] 7. Modification Example of Laser Device Next, a modification example of the laser device 2 will be described. The laser device 2 shown in FIG. 2 uses a Fabry - Perot resonator as an optical resonator. The laser device 2 according to this modification example includes an unstable resonator instead of the Fabry - Perot resonator.

[0151] FIG. 25 schematically shows the configuration of the laser device 2 according to the modification example. In this modification example, instead of the rear mirror 25a and the output coupling mirror 25b, it includes a cylindrical concave mirror 29a and a cylindrical convex mirror 29b.

[0152] The concave mirror 29a is disposed on the rear side of the chamber 21. The convex mirror 29b is disposed on the front side of the chamber 21. The concave mirror 29a and the convex mirror 29b have their respective focal axes coinciding with each other, and expand the beam diameter in the V direction. The magnification is in the range of 5 to 15 times. The concave mirror 29a and the convex mirror 29b constitute an unstable resonator that is unstable only in the V direction.

[0153] The laser beam Lb output from the laser device 2 according to this modification has a small number of spatial transverse modes in the V direction, and the M square value Mv in the V direction 2 becomes small. By setting the magnification in the V direction to an appropriate value, the M square value Mv in the V direction 2 and the M square value Mh in the H direction 2 can be made substantially the same. For example, it is preferable that the magnification in the V direction is in the range of 10 to 13 times.

[0154] FIG. 26 schematically shows the beam shape of the laser beam Lb cut along the D-D line shown in FIG. 25 on the VH plane. The beam shape is a rectangular shape that is longer in the V direction than in the H direction.

[0155] By using an unstable resonator, the number of spatial transverse modes in the V direction can be made closer to the number of spatial transverse modes in the H direction. As a result, the diameter of the hole 45b to be processed can be made smaller than in the case of using a Fabry-Perot resonator, and hole processing can be performed efficiently. Also, by using an unstable resonator, resonator loss can be suppressed, and an output comparable to that in the case of using a Fabry-Perot resonator can be obtained.

[0156] Note that the concave mirror 29a and the convex mirror 29b may each be spherical, and the optical resonator may be an unstable resonator that is unstable in the V direction and the H direction. In this case, it is preferable to arrange the concave mirror 29a and the convex mirror 29b so that their focal positions coincide. Also, it is preferable that the magnification is in the range of 5 to 10 times. In this case, since the unstable resonator expands the beam diameter in the V direction and the H direction, the M square value Mv in the V direction 2 and the M square value Mh in the H direction2 Both can be made smaller.

[0157] 8. Beam expander Next, the specific configuration of the beam expander 51 will be described.

[0158] FIG. 27 schematically shows the configuration of a fixed magnification beam expander 51. The fixed magnification beam expander 51 includes a combined lens formed by combining a spherical convex lens 51a and a spherical concave lens 51b. The convex lens 51a and the concave lens 51b are arranged along the optical axis so that their focal positions coincide. If the focal length of the convex lens 51a is F1 and the focal length of the concave lens 51b is F2, the magnification Mbm is expressed by the relational expression Mbm = F1 / F2.

[0159] FIGS. 28 and 29 schematically show the configuration of a variable magnification beam expander 51. The variable magnification beam expander 51 includes spherical convex lenses 90 to 92 and actuators 93, 94. The convex lenses 90 to 92 are arranged along the optical axis. The actuators 93, 94 move the convex lenses 90, 91 in the optical axis direction, respectively. For example, the actuators 93, 94 are one-axis moving stages and are controlled by the laser processing processor 40.

[0160] FIG. 28 shows a state with a low magnification, and FIG. 29 shows a state with a high magnification. The laser processing processor 40 can change the magnification of the beam expander 51 by controlling the actuators 93, 94 to move the convex lenses 90, 91. <00>

[0161] Note that a beam expander with variable magnification in the V direction and a beam expander with variable magnification in the H direction may be arranged along the optical axis. In this case, the magnification in the V direction and the magnification in the H direction can be controlled individually.

[0162] 9. Optical axis monitor Next, the specific configuration of the optical axis monitor 81 will be described.

[0163] Figure 30 schematically shows the configuration of the optical axis monitor 81. The optical axis monitor 81 includes a first beam profiler 86, a second beam profiler 87, a beam splitter 88, a transfer lens 89a, and a condenser lens 89b. The beam splitter 88 is disposed on the optical path of the laser beam Lb reflected by the beam splitter 85 shown in the second modification of the first embodiment.

[0164] The transfer lens 89a is disposed on the optical path of the laser beam Lb that has passed through the beam splitter 88, and transfers the incident laser beam Lb to the first beam profiler 86. The first beam profiler 86 measures the position of the cross-sectional intensity profile of the laser beam Lb.

[0165] The condenser lens 89b is disposed on the optical path of the laser beam Lb reflected by the beam splitter 88, and condenses the incident laser beam Lb onto the second beam profiler 87. The second beam profiler 87 measures the center position of the condensing point.

[0166] The optical axis of the laser beam Lb can be measured from the position of the cross-sectional intensity profile measured by the first beam profiler 86 and the center position of the condensing point measured by the second beam profiler 87.

[0167] 10. Modification of the optical device Next, a modification of the optical device 41 will be described. The optical device 41 according to this modification differs from the first embodiment only in the configurations of the illumination optical system 50 and the projection optical system 60.

[0168] FIG. 31 partially shows the illumination optical system 50 and the projection optical system 60 according to a modified example. In each of the above embodiments, the projection optical system 60 is disposed on the downstream side of the illumination optical system 50. In this modified example, as shown in FIG. 31, the first condensing optical system 53, the first collimating optical system 61, the second condensing optical system 54, and the second collimating optical system 62 are arranged in this order from the upstream side. Further, a first optical slit 71 is disposed between the first condensing optical system 53 and the first collimating optical system 61, and a second optical slit 72 is disposed between the second condensing optical system 54 and the second collimating optical system 62.

[0169] The second condensing optical system 54 is provided with an actuator 55 that enables the distance between the cylindrical convex lens 54a and the cylindrical concave lens 54b to be changed, similar to the first modified example of the first embodiment.

[0170] Thus, in this modified example, the illumination optical system 50 and the projection optical system 60 are separated in the V direction and the H direction. In this modified example, although the optical path becomes longer compared to the first embodiment, since the condensing in the V direction and the condensing in the H direction are performed completely separately, the fluence at the first optical slit 71 and the second optical slit 72 can be made smaller.

[0171] Note that the second condensing optical system 54, the second collimating optical system 62, the first condensing optical system 53, and the first collimating optical system 61 may be arranged in this order from the upstream side.

[0172] 11. Method for manufacturing an electronic device The laser processing method according to each of the above embodiments and modified examples 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.

[0173] FIG. 32 schematically shows the configuration of the electronic device 100. The electronic device 100 shown in FIG. 32 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.

[0174] 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.

[0175] 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.

[0176] FIG. 33 shows a manufacturing method of the electronic device 100. As shown in FIG. 33, 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.

[0177] 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.

[0178] 12. Configuration Example of 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 typified by an FPGA (Field Programmable Gate Array) or an ASIC (Application Specific Integrated Circuit). The laser processing processor 40 stores the above-described various data in the memory.

[0179] The above description is intended to be illustrative and not restrictive. Thus, it will be apparent to those skilled in the art that various changes may be made to the embodiments of the present disclosure without departing from the scope of the appended claims.

[0180] 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 as meaning "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 as including combinations with those other than "A", "B", and "C".

Claims

1. A laser processing apparatus for performing hole processing by irradiating a workpiece with laser light output from a laser device, comprising: a first optical slit disposed at a first position on the optical path of the laser light and having an opening extending in a second direction orthogonal to the first direction; a second optical slit disposed at a second position different from the first position on the optical path of the laser light and having an opening extending in the first direction; a first condensing optical system for condensing the laser light in the first direction so as to form a first line shape and irradiating the first optical slit; and a second condensing optical system for condensing the laser light in the second direction so as to form a second line shape and irradiating the second optical slit, the illumination optical system including the first and second condensing optical systems; a projection optical system for imaging the laser light transmitted through the first optical slit and the second optical slit on the surface of the workpiece so as to represent the shape of an overlapping portion between the opening of the first optical slit and the opening of the second optical slit; A laser processing apparatus comprising the above components.

2. The laser processing apparatus according to claim 1, wherein the projection optical system includes a first collimating optical system for collimating the laser light transmitted through the first optical slit in the first direction; a second collimating optical system for collimating the laser light transmitted through the second optical slit in the second direction; an imaging optical system for imaging the laser light transmitted through the first optical slit and the second optical slit on the surface of the workpiece; a diaphragm disposed between the first optical slit, the second optical slit and the imaging optical system; and includes the above components.

3. The laser processing apparatus according to claim 2, wherein the first collimating optical system and the second collimating optical system have the same focal length, and the first collimating optical system and the second collimating optical system are arranged such that the first optical slit and the second optical slit are located at the front focal positions thereof, respectively.

4. The laser processing apparatus according to claim 2, wherein the diaphragm has a thread-wound shape symmetric with respect to the first direction and the second direction.

5. The laser processing apparatus according to claim 2, wherein the opening of the first optical slit and the opening of the second optical slit each have a barrel shape symmetric with respect to the first direction and the second direction.

6. The laser processing apparatus according to claim 2, wherein the first collimating optical system and the second collimating optical system each include a cylindrical convex lens.

7. The laser processing apparatus according to claim 2, wherein the first collimating optical system and the second collimating optical system each include a lens combination of a cylindrical convex lens and a cylindrical concave lens.

8. The laser processing apparatus according to claim 2, wherein a diffractive optical element is disposed between the aperture and the imaging optical system and divides the laser light that has passed through the aperture into a plurality of beams.

9. The laser processing apparatus according to claim 1, wherein the projection optical system includes a first collimating optical system that collimates the laser light transmitted through the first optical slit in the first direction, a second collimating optical system that collimates the laser light transmitted through the second optical slit in the second direction, an aperture disposed on the optical path of the laser light transmitted through the first optical slit and the second optical slit, and a diffractive optical element that divides the laser light that has passed through the aperture into a plurality of beams and forms an image of each beam on the surface of the workpiece.

10. The laser processing apparatus according to claim 1, wherein the first condensing optical system and the second condensing optical system each include a cylindrical convex lens.

11. The laser processing apparatus according to claim 1, wherein the first condensing optical system and the second condensing optical system each include a lens combination of a cylindrical convex lens and a cylindrical concave lens. [[ID= ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ When the width of the first slit is larger than the full width at half maximum of the beam waist of the laser beam in the first direction, control the first actuator to shift the beam waist position of the laser beam in the first direction from the first position. When the width of the second slit is larger than the full width at half maximum of the beam waist of the laser beam in the second direction, control the second actuator to shift the beam waist position of the laser beam in the second direction from the second position.

15. The laser processing apparatus according to claim 13, comprising a variable magnification beam expander disposed upstream of the illumination optical system. The processor When the width of the first slit is larger than the full width at half maximum of the beam waist of the laser beam in the first direction, or when the width of the second slit is larger than the full width at half maximum of the beam waist of the laser beam in the second direction, control the magnification of the beam expander so that the width of the first slit is equal to or less than the full width at half maximum of the beam waist of the laser beam in the first direction, and the width of the second slit is equal to or less than the full width at half maximum of the beam waist of the laser beam in the second direction.

16. The laser processing apparatus according to claim 2, wherein the numerical aperture of the imaging optical system is in the range of 0.03 to 0.

06.

17. The laser processing apparatus according to claim 16, wherein the projection magnification of the projection optical system is in the range of 1 / 30 to 1 / 10.

18. The laser processing apparatus according to claim 17, When the numerical aperture of the imaging optical system is NAi, the projection magnification of the projection optical system is Mg, and the numerical aperture of each of the first condensing optical system and the second condensing optical system is NAil, the relationship NAil = NAi × Mg is satisfied.

19. A laser processing system for performing hole processing by irradiating a workpiece with laser light output from a laser device, the laser device for outputting the laser light, a first optical slit disposed at a first position on the optical path of the laser light and having an aperture extending in a second direction orthogonal to the first direction, a second optical slit disposed at a second position different from the first position on the optical path of the laser light and having an aperture extending in the first direction. A first condensing optical system that condenses the laser light in the first direction so as to have a first line shape and irradiates the first optical slit, and a second condensing optical system that condenses the laser light in the second direction so as to have a second line shape and irradiates the second optical slit, and an illumination optical system including the second condensing optical system, A projection optical system that forms an image of the laser light transmitted through the first optical slit and the second optical slit on the surface of the workpiece so as to represent the shape of an overlapping portion between an opening of the first optical slit and an opening of the second optical slit, A laser processing system comprising the same.

20. The laser processing system according to claim 19, wherein the laser device is a discharge-excited type, and a discharge direction corresponds to the first direction.

21. The laser processing system according to claim 20, wherein the first position is a beam waist position of the laser light in the first direction, and the second position is a beam waist position of the laser light in the second direction.

22. The laser processing system according to claim 20, wherein the laser device is an excimer laser device and includes an unstable resonator that is unstable only in the discharge direction.

23. The laser processing system according to claim 20, wherein the laser device is an excimer laser device and includes an unstable resonator that is unstable in the discharge direction and a direction orthogonal to the discharge direction.

24. The laser processing system according to claim 23, wherein a magnification of the laser light by the unstable resonator is in a range of 5 to 10 times.

25. A method for manufacturing an electronic device, wherein a laser processing apparatus performs drilling by irradiating a workpiece with laser light output from a laser device, a first optical slit disposed at a first position on an optical path of the laser light and having an opening extending in a second direction orthogonal to the first direction, a second optical slit disposed at a second position different from the first position on the optical path of the laser light and having an opening extending in the first direction, a first condensing optical system that condenses the laser light in the first direction so as to have a first line shape and irradiates the first optical slit, and a second condensing optical system that condenses the laser light in the second direction so as to have a second line shape and irradiates the second optical slit, and an illumination optical system including the second condensing optical system, A projection optical system that forms an image of the laser light that has passed through the first optical slit and the second optical slit on the surface of the workpiece so as to represent the shape of the overlapping portion between the aperture of the first optical slit and the aperture of the second optical slit; Forming a plurality of through holes in a glass substrate as the workpiece by a laser processing apparatus including; Coupling an interposer having the glass substrate and conductors provided in each of the plurality of through holes to an integrated circuit chip and electrically connecting them to each other; Coupling the interposer and the circuit board to each other and electrically connecting them; A method for manufacturing an electronic device including.

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