Laser processing system and method of manufacturing electronic device

Abstract

To provide a laser processing system and a method of manufacturing an electronic device.SOLUTION: A laser processing system according to one standpoint of the present disclosure comprises: laser equipment that outputs a laser beam having two or more space modes; a branched optical element that is arranged on an optical path of the laser beam and that bifurcates the laser beam into a plurality of branched beams reducing the number of the space modes; and at least one split-type diffraction optical element that splits each of the plurality of branched beams into a plurality of split beams on a surface of a workpiece.SELECTED DRAWING: Figure 7

Description

[Technical Field]

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

[0002] In recent years, semiconductor exposure devices have been required to improve their resolution in response to the miniaturization and high integration of semiconductor integrated circuits. To this end, the wavelength of light emitted from exposure light sources has been shortened. For example, KrF excimer laser devices, which output laser light with a wavelength of approximately 248.4 nm, and ArF excimer laser devices, which output laser light with a wavelength of approximately 193.4 nm, are used as gas laser devices for exposure.

[0003] Furthermore, since excimer laser light has a pulse width of approximately several tens of nanoseconds and a short wavelength, it is sometimes used for direct processing of polymeric materials, glass materials, and the like.

[0004] Chemical bonds in polymeric materials can be cut by excimer laser light, which has a photon energy higher than the bond energy. Therefore, it is known that excimer laser light enables non-heating processing of polymeric materials, resulting in clean processed shapes.

[0005] Furthermore, it is known that glass, ceramics, and the like have a high absorptivity for excimer laser light, so that even materials that are difficult to process with visible or infrared laser light can be processed with excimer laser light. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Summary of the specification of U.S. Patent Application Publication No. 2020 / 070280

[0007] A laser processing system according to one aspect of the present disclosure includes a laser device that outputs laser light having two or more spatial modes, a branching optical element that is arranged on the optical path of the laser light and branches the laser light into a plurality of branched beams with a reduced number of spatial modes, and at least one split diffractive optical element that splits each of the plurality of branched beams into a plurality of split beams on the surface of a workpiece.

[0008] A method for manufacturing an electronic device according to one aspect of the present disclosure includes: laser processing an interposer substrate to produce an interposer using a laser processing system including a laser device that outputs laser light having two or more spatial modes, a branching optical element that is arranged on the optical path of the laser light and branches the laser light into a plurality of branched lights with a reduced number of spatial modes, and at least one segmented diffractive optical element that splits each of the plurality of branched lights into a plurality of split lights on the surface of a workpiece; bonding the interposer and an integrated circuit chip to electrically connect them to each other; and bonding the interposer and a circuit board to electrically connect them to each other. [Brief explanation of the drawings]

[0009] Some embodiments of the present disclosure will now be described, by way of example only, with reference to the accompanying drawings, in which: [Figure 1] FIG. 1 is a diagram schematically showing the configuration of a laser processing system according to a comparative example. [Figure 2] FIG. 2 is a diagram schematically illustrating the configuration of a laser device. [Figure 3] FIG. 3 is a diagram showing an example of elements constituting a DOE. [Figure 4] FIG. 4 is a diagram showing an example of a DOE. [Figure 5] FIG. 5 is a diagram showing a plurality of laser beams split by a DOE. [Figure 6] FIG. 6 is a diagram showing an example in which the number of focused spots is increased using a beam splitter. [Figure 7] FIG. 7 is a diagram schematically showing the configuration of the laser processing system according to the first embodiment. [Figure 8]FIG. 8 is a diagram schematically showing the configuration of a laser processing system according to the second embodiment. [Figure 9] FIG. 9 is a diagram showing an example of the configuration of a light-collecting element array. [Figure 10] FIG. 10 is a diagram showing the simulation results of the focused spots formed in the second embodiment. [Figure 11] FIG. 11 is a diagram showing the simulation results of the focused spots formed in the comparative example. [Figure 12] FIG. 12 is a diagram showing a modified example of the light-collecting element array. [Figure 13] FIG. 13 is a diagram schematically showing the configuration of a laser processing system according to the third embodiment. [Figure 14] FIG. 14 is a diagram showing deflection by a prism. [Figure 15] FIG. 15 is a diagram showing deflection by a DOE. [Figure 16] FIG. 16 is a diagram schematically illustrating the configuration of an electronic device. [Figure 17] FIG. 17 is a flowchart showing a method for manufacturing an electronic device. Embodiment

[0010] <Contents> 1. Comparative Example 1.1 Configuration 1.2 Operation 1.3 Diffractive optical elements 1.4 Challenges 2. First embodiment 2.1 Configuration 2.2 Operation 2.3 Effects 3. Second embodiment 3.1 Configuration 3.2 Operation 3.3 Effects 3.4 Simulation 3.5 Variations 4. Third embodiment 4.1 Configuration 4.2 Operation 4.3 Effects 5. Electronic Device Manufacturing Method

[0011] 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. Furthermore, not all of the configurations and operations described in each embodiment are necessarily essential to the configurations and operations of the present disclosure. Note that the same components are given the same reference symbols, and redundant explanations will be omitted.

[0012] 1. Comparative Example 1.1 Configuration 1 shows a schematic configuration of a laser processing system 1 according to a comparative example. Note that the comparative example is a configuration that the applicant recognizes as being known only by the applicant, and is not a publicly known example that the applicant acknowledges.

[0013] 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 to form holes such as via holes in a glass substrate for an interposer.

[0014] The laser device 2 is a laser device that outputs ultraviolet pulsed laser light. For example, the laser device 2 is a discharge-pumped laser device that outputs ultraviolet pulsed laser light using F2, ArF, KrF, XeCl, XeF, or the like as a laser medium. In this disclosure, the laser device 2 is a KrF excimer laser device that outputs ultraviolet pulsed laser light with a center wavelength of 248.4 nm. Hereinafter, the ultraviolet pulsed laser light output by the laser device 2 will be simply referred to as laser light Lb.

[0015] The laser device 2 and the laser processing device 4 are connected by an optical path 5. The optical path 5 is disposed on the optical path of the laser light Lb between the exit port of the laser device 2 and the entrance port of the laser processing device 4.

[0016] The laser processing apparatus 4 includes a laser processing processor 40, an optical device 41, a frame 42, an XYZ stage 43, and a table 44. The optical device 41 and the XYZ stage 43 are fixed to the frame 42.

[0017] The table 44 supports a workpiece 45. The workpiece 45 is a processing target for drilling holes. The workpiece 45 is a glass substrate for an interposer, for example, an alkali-free glass substrate. The workpiece 45 may also be a substrate made of quartz glass, an organic material, silicon single crystal, ceramics, or the like. A plurality of holes H are formed in the workpiece 45 by so-called multi-point drilling.

[0018] The XYZ stage 43 supports a table 44. A workpiece 45 is fixed on the table 44. The XYZ stage 43 allows the table 44 to move in the X, Y, and Z directions, and by moving the table 44, the position of the workpiece 45 is changed. The X, Y, and Z directions are perpendicular to one another. The X and Y directions are parallel to the surface 45a of the workpiece 45. The Z direction is perpendicular to the surface 45a. The XYZ stage 43 is a moving stage that allows the workpiece 45 to move in a direction perpendicular to the optical axis of the condenser lens 60.

[0019] The optical device 41 includes a housing 41a, high-reflection mirrors 47a, 47b, and 47c, an attenuator 49, a diffractive optical element (DOE) 50, and a condenser lens 60. Each component in the optical device 41 is fixed to a holder (not shown), and is disposed at a predetermined position in the housing 41a.

[0020] High-reflection mirror 47a is arranged to reflect laser light Lb that has passed through optical path tube 5, and the reflected laser light Lb passes through attenuator 49 and enters high-reflection mirror 47b. Optical path tube 5 and housing 41a are purged with, for example, a purge gas. The purge gas is nitrogen gas, an inert gas, or the like, which hardly absorbs laser light Lb.

[0021] The attenuator 49 is disposed in the housing 41a on the optical path between the high-reflection mirror 47a and the high-reflection mirror 47b. The attenuator 49 includes, for example, two partial reflection mirrors 49a and 49b and rotation stages 49c and 49d for these partial reflection mirrors. The partial reflection mirrors 49a and 49b are optical elements whose transmittance changes depending on the angle of incidence of the laser beam Lb. The angle of incidence of the laser beam Lb is adjusted for the partial reflection mirrors 49a and 49b by the rotation stages 49c and 49d.

[0022] The high-reflection mirrors 47b and 47c are arranged to reflect the laser light Lb that has passed through the attenuator 49, and the reflected laser light Lb enters the DOE .

[0023] The DOE 50 is disposed on the optical path of the laser beam Lb reflected by the high-reflection mirror 47c. The DOE 50 diffracts the laser beam Lb incident from the high-reflection mirror 47c to split the laser beam Lb into multiple laser beams Lv with different emission angles. That is, the DOE 50 splits the laser beam Lb in the X direction and the Y direction. In the present disclosure, "splitting" refers to splitting the incident laser beam into multiple laser beams without reducing the number of spatial modes.

[0024] The condenser lens 60 is disposed so that the plurality of laser beams Lv emitted from the DOE 50 are incident thereon and the focal plane is located on the surface 45a of the workpiece 45. The condenser lens 60 is, for example, an Fθ lens, and condenses each of the plurality of laser beams Lv emitted from the DOE 50 to generate a multi-point pattern in which a plurality of condensed light spots are arranged in a grid pattern.

[0025] 2 shows a schematic 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 consisting of a rear mirror 25a and an output coupling mirror 25b, a charger 23, and a power supply unit (PPM: Pulsed Power Module) 22.

[0026] Windows 21a and 21b are provided in the chamber 21. The chamber 21 is filled with a laser gas as a laser medium.

[0027] An opening is formed in the chamber 21, and an electrically insulating plate 26 with multiple feedthroughs 26a embedded therein is provided to close the opening. The PPM 22 is disposed on the electrically insulating plate 26. A pair of discharge electrodes 27a, 27b serving as main electrodes, and a ground plate 28 are disposed within the chamber 21. The discharge surfaces of the discharge electrodes 27a, 27b are rectangular in shape.

[0028] The discharge electrodes 27a and 27b are arranged so that their discharge surfaces face each other in order to excite the laser medium by discharge. The surface of the discharge electrode 27a opposite the discharge surface is supported by an electrically insulating plate 26. The discharge electrode 27a is connected to a feedthrough 26a. The surface of the discharge electrode 27b opposite the discharge surface is supported by a ground plate 28.

[0029] 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 a feedthrough 26a via a connection (not shown). The charger 23 charges the charging capacitor under control of the laser processor 38.

[0030] The switch 22a is controlled to be turned on / off by the laser processor 38. The laser processor 38 turns on the switch 22a in response to a light emission trigger Tr transmitted from the laser processing processor 40.

[0031] When switch 22a is turned on, current flows from the charging capacitor to the primary side of the pulse transformer, and electromagnetic induction causes a reverse current to flow to the secondary side of the pulse transformer. A 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, a dielectric breakdown occurs in the laser gas between discharge electrodes 27a and 27b, causing a discharge. This discharge generates one pulse of laser light Lb.

[0032] The rear mirror 25a is formed by coating a highly reflective film on a flat substrate. The output coupling mirror 25b is formed by coating a partially reflective film on a flat substrate. The chamber 21 is disposed between the rear mirror 25a and the output coupling mirror 25b. The laser light Lb generated in the chamber 21 is amplified by an optical resonator and output from the output coupling mirror 25b.

[0033] The monitor module 30 includes a beam splitter 31 and an optical sensor 32. The beam splitter 31 is disposed on the optical path of the laser light Lb output from the output coupling mirror 25b and reflects a portion of the laser light Lb. The optical sensor 32 is disposed at a position where the laser light Lb reflected by the beam splitter 31 is incident. The optical sensor 32 measures the pulse energy of the laser light Lb and transmits the measurement value to a laser processor 38.

[0034] The laser processor 38 controls the pulse energy of the laser light Lb output from the laser device 2 to be equal to the target pulse energy Et by changing the charging voltage of the charger 23 based on the pulse energy measured by the optical sensor 32.

[0035] The shutter 35 is disposed on the optical path of the laser light Lb that passes through the beam splitter 31. The shutter 35 opens and closes in response to commands from the laser processor 38. The laser processor 38 controls the shutter 35 to control the output of the laser light Lb from the laser device 2.

[0036] 1.2 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 XYZ stage 43 so that the focal plane of the condenser lens 60 coincides with the surface 45a of the workpiece 45. Next, the laser processing processor 40 transmits a target pulse energy Et to the laser device 2 and controls the transmittance Ta of the attenuator 49 so that the fluence on the surface 45a becomes the target fluence Ft.

[0037] Here, the fluence is the pulse energy density per pulse of one focused spot on the surface 45a of the workpiece 45. When the transmittance of the attenuator 49 is 100%, the transmittance of the optical device 41 is T0, the number of focused spots is Q, and the area of ​​the focused spot is S, the target fluence Ft is expressed by the following formula (1). Ft=Et×Ta×T0 / (Q×S) ···(1)

[0038] When the laser processor 38 receives the target pulse energy Et, it controls the charger 23 so that the pulse energy of the laser light Lb becomes the target pulse energy Et. Next, the laser processor 38 inputs a trigger to the switch 22a to cause the oscillator 20 to naturally oscillate. At this time, the shutter 35 is in a closed state.

[0039] The pulse energy of laser light Lb output from chamber 21 via output coupling mirror 25 is measured by sampling a portion of the laser light Lb in monitor module 30. Laser processor 38 controls charger 23 so that the difference ΔE between the pulse energy and target pulse energy Et approaches zero. When the difference ΔE falls within an allowable range, laser processor 38 sends an enable signal to laser processing processor 40 and opens shutter 35.

[0040] When the laser processing processor 40 receives the enable signal, it transmits a light emission trigger Tr with a predetermined repetition frequency and a predetermined number of pulses to the laser device 2. As a result, laser light Lb is output from the laser device 2 in synchronization with the light emission trigger Tr and enters the laser processing device 4 via the optical path 5. This laser light Lb is reflected by the high-reflection mirror 47a, attenuated by the attenuator 49, and then reflected by the high-reflection mirrors 47b and 47c. The laser light Lb reflected by the high-reflection mirror 47c enters the DOE 50.

[0041] The DOE 50 splits the incident laser beam Lb into multiple laser beams Lv on the surface 45a of the workpiece 45. The condenser lens 60 forms a multi-point pattern by condensing each of the multiple laser beams Lv on the surface 45a of the workpiece 45. A predetermined number of pulses of the laser beam Lv are irradiated onto each condensed spot of the multi-point pattern, thereby causing laser ablation and forming holes H.

[0042] Next, the laser processing processor 40 controls the XYZ stage 43 and the laser device 2 to repeatedly change the irradiation position and irradiate the multi-point pattern using a step-and-repeat method, thereby forming multiple holes H throughout the entire processing area where hole processing is required.

[0043] 1.3 Diffractive optical elements Next, the DOE will be described. Generally, DOEs are roughly classified into segmented DOEs that split a beam into multiple beams and shaping DOEs that shape the beam. The DOE 50 of the present disclosure is a segmented DOE. The DOE 50 is fabricated by engraving a pattern on a substrate such as quartz.

[0044] In general, it is difficult to fabricate a large-area DOE with a single pattern. For example, when generating a pattern using a computer, doubling the area of ​​the DOE requires four times as much memory and calculation time. Therefore, DOEs with smaller areas are easier to design and fabricate. However, reducing the area of ​​the DOE reduces the numerical aperture of the entire optical system, resulting in a decrease in resolution. For this reason, it is preferable to fabricate a large-area DOE by pasting together multiple elements with a basic pattern formed into a tiled pattern. This can prevent a decrease in resolution.

[0045] 3 shows an example of an element 51 that constitutes the DOE 50. The element 51 is a rectangular plate on which a basic pattern is formed.

[0046] 4 shows an example of a DOE 50. The DOE 50 is constructed by pasting together a plurality of elements 51 in a tiled pattern. That is, the DOE 50 is constructed by repeatedly arranging the elements 51. The basic patterns are designed so that the patterns are continuous at the boundaries between adjacent basic patterns.

[0047] 1.4 Challenges The laser device 2 is capable of high output and high repetition rate, making it suitable for multi-point hole drilling using a DOE 50. On the other hand, when drilling holes, a high beam quality of the laser light Lb is advantageous in terms of processing speed and processing accuracy, but since the laser light Lb is multimode, it has a large number of spatial modes and low beam quality. Multimode means that the number of spatial modes is two or more. A spatial mode is a mode in a direction perpendicular to the optical axis of the optical resonator, i.e., a transverse mode. When the laser device 2 is an excimer laser device, the number of spatial modes is approximately 10 to 1,000.

[0048] 5, each of the multiple laser beams Lv split by the DOE 50 has the same number of spatial modes as the laser beam Lb incident on the DOE 50 and therefore has beam quality equivalent to that of the laser beam Lb. Therefore, in the laser processing system 1 according to the comparative example, the beam quality of the laser beam Lb output from the laser device 2 is low, which causes a problem that the focused spot diameter of the laser beam Lv focused by the focusing lens 60 becomes large, resulting in reduced processing speed and processing accuracy.

[0049] Furthermore, in multi-point hole processing, it is desirable to increase the number of focused spots in order to simultaneously form a large number of holes H from the viewpoint of throughput. However, in the laser processing system 1 according to the comparative example, when an attempt is made to increase the number of focused spots, the pattern becomes complicated, which makes it difficult to design and manufacture the DOE 50.

[0050] In order to increase the number of focused spots, as shown in Fig. 6, it is conceivable to split the laser light Lb into two laser lights Lb using a beam splitter BS, and then split each of the two split laser lights Lb into multiple laser lights Lv using a DOE 50. The multiple laser lights Lv split by each DOE 50 are focused by a focusing lens 60. This doubles the number of focused spots.

[0051] 6, however, the beam quality of each of the two laser beams Lb split by the beam splitter BS is low because the number of spatial modes of the laser beam Lb incident on the beam splitter BS is the same. Therefore, even if the number of focused spots is increased using the beam splitter BS, the focused spot diameter remains large, and the processing speed and processing accuracy decrease.

[0052] The present disclosure provides a laser processing system and a method for manufacturing an electronic device that can increase the number of focused spots and improve the processing speed and processing accuracy even when multi-mode laser light Lb is used.

[0053] 2. First embodiment A laser processing system 1a according to a first embodiment of the present disclosure will be described. Note that the same components as those described above will be assigned the same reference numerals, and redundant description will be omitted unless otherwise specified.

[0054] 2.1 Configuration 7 shows a schematic configuration of a laser processing system 1a according to the first embodiment. Except for the optical device 41, the laser processing system 1a has the same configuration as the laser processing system 1 according to the comparative example.

[0055] In this embodiment, a wedge plate 70 is disposed in the optical path of the laser beam Lb incident on the high-reflection mirror 47c within the optical device 41. For example, the wedge plate 70 is formed of synthetic quartz and has a highly reflective coating applied to its surface. The wedge plate 70 highly reflects a portion of the laser beam Lb, thereby splitting the laser beam Lb into two laser beams Lc with a reduced number of spatial modes. The wedge plate 70 preferably splits the laser beam Lb so that the number of spatial modes of each of the two laser beams Lc is equal. Note that in the present disclosure, splitting the incident laser beam into multiple laser beams with a reduced number of spatial modes is referred to as "splitting." The wedge plate 70 is an example of a "splitting optical element" according to the technology of the present disclosure. The laser beam Lc is an example of a "splitting light" according to the technology of the present disclosure.

[0056] Furthermore, the wedge plate 70 is preferably arranged to split the laser beam Lb in a direction corresponding to the discharge direction of the laser device 2. This is because the laser beam Lb has a large number of spatial modes in the direction corresponding to the discharge direction and has low beam quality in the direction corresponding to the discharge direction. In the optical path between the high-reflection mirror 47b and the high-reflection mirror 47c where the wedge plate 70 is arranged, the Z direction corresponds to the discharge direction.

[0057] In this embodiment, the DOE 50 and the condenser lens 60 are disposed on the optical paths of the two laser beams Lc branched by the wedge plate 70. Specifically, the laser beam Lb is branched into the laser beam Lc reflected by the wedge plate 70 and the laser beam Lc that is incident on the high-reflection mirror 47c without being reflected by the wedge plate 70. The DOE 50 and the condenser lens 60 are disposed on the optical path of the laser beam Lc reflected by the wedge plate 70 and the optical path of the laser beam Lc that is not reflected by the wedge plate 70 but is incident on the high-reflection mirror 47c and reflected therefrom.

[0058] The configurations of the DOE 50 and the condenser lens 60 are similar to those of the DOE 50 and the condenser lens 60 according to the comparative example. In this embodiment, the DOE 50 splits the incident laser beam Lc into multiple laser beams Lv with different emission angles. The condenser lens 60 is arranged so that the multiple laser beams Lv emitted from the DOE 50 are incident on the condenser lens 60 and the focal plane is located on the surface 45a of the workpiece 45. The laser beams Lv are an example of "split beams" according to the technology of the present disclosure.

[0059] The length of the elements 51 that make up the DOE 50 is preferably equal to or less than half the length of the coherence region of the laser light Lb.

[0060] When the number of spatial modes of laser light Lb is M, there are M coherence regions in the cross section of laser light Lb, and each coherence region has the same area. Within one coherence region, the phases are aligned and the light is spatially coherent. Between two coherence regions, the phases are not aligned and the light is spatially incoherent.

[0061] 2.2 Operation The operation of the laser processing system 1a according to the first embodiment is similar to the operation of the laser processing system 1 according to the comparative example.

[0062] In this embodiment, the laser beam Lb is split into two laser beams Lc by the wedge plate 70, and each laser beam Lc is split into a plurality of laser beams Lv by the DOE 50, so that twice as many focused spots as in the comparative example are formed on the surface 45a of the workpiece 45. As a result, in this embodiment, twice as many holes H as in the comparative example are simultaneously formed.

[0063] 2.3 Effects Each of the two laser beams Lc split by the wedge plate 70 has a reduced number of spatial modes, similar to when a portion of the laser beam Lb is extracted using an aperture or a slit. In this embodiment, the number of spatial modes of each of the two laser beams Lc is approximately half that of the laser beam Lb. In this manner, in this embodiment, the number of spatial modes of the laser beam Lc incident on the DOE 50 is reduced, and therefore the number of spatial modes of each of the multiple laser beams Lv split by the DOE 50 is also reduced. This improves the beam quality of the laser beam Lv that forms the focused spot, thereby reducing the focused spot diameter and improving the processing speed and processing accuracy.

[0064] Furthermore, in this embodiment, a DOE 50 is disposed in each optical path of the two laser beams Lc split by the wedge plate 70, so that a DOE 50 similar to that in the comparative example can be used. That is, according to this embodiment, the number of focused spots can be increased without fabricating a large-area DOE having a complex pattern. Therefore, according to this embodiment, even when a multimode laser beam is used, it is possible to increase the number of focused spots and improve the processing speed and processing accuracy.

[0065] In the first embodiment, the laser light Lb is split into two laser lights Lc by one wedge plate 70, but two or more wedge plates 70 may be used to split the laser light Lb into three or more laser lights Lc. In this case, the DOE 50 and the condenser lens 60 may be disposed in the optical path of each of the split laser lights Lc. However, it is preferable that the number of splits is equal to or less than the number of spatial modes of the laser light Lb. In other words, it is preferable that the beam cross-sectional area of ​​each of the split laser lights Lc is larger than the area of ​​one coherence region of the laser light Lb.

[0066] 3. Second embodiment A laser processing system 1b according to a second embodiment of the present disclosure will be described. Note that the same components as those described above are denoted by the same reference numerals, and redundant description will be omitted unless otherwise specified.

[0067] 3.1 Configuration 8 shows a schematic configuration of a laser processing system 1b according to the second embodiment. Except for the optical device 41, the laser processing system 1b has the same configuration as the laser processing system 1 according to the comparative example.

[0068] The laser processing system 1b differs from the laser processing system 1 according to the comparative example in that a focusing element array 80 is provided in the optical device 41 instead of the focusing lens 60. The focusing element array 80 functions as a branching optical element.

[0069] 9, the light-collecting element array 80 is configured by arranging a plurality of light-collecting lenses 81 in a matrix. For example, the light-collecting element array 80 has two light-collecting lenses 81 arranged in each of the X and Y directions. The number of light-collecting lenses 81 constituting the light-collecting element array 80 can be changed as appropriate. The light-collecting lens 81 is an example of a "light-collecting element" according to the technology of the present disclosure.

[0070] In this embodiment, the light-collecting element array 80 is disposed downstream of the DOE 50. The distance D between the DOE 50 and the light-collecting element array 80 is preferably set to the minimum value allowed by the structure. For example, the distance D is preferably 50 mm or less, and more preferably 25 mm or less.

[0071] The laser beam Lb incident on the DOE 50 is not yet split immediately after being emitted from the DOE 50, and is split into multiple laser beams Lv as the diffracted waves emitted from the DOE 50 form an image at a distance. For this reason, the focusing element array 80, which is disposed downstream of and close to the DOE 50, acts to split the laser beam Lb into four laser beams Lc with a reduced number of spatial modes. In this embodiment, the focusing element array 80 splits the laser beam Lb into four laser beams Lc.

[0072] Furthermore, each of the focusing lenses 81 constituting the focusing element array 80 is arranged to focus each of the branched laser beams Lc onto the surface 45a of the workpiece 45. At the focusing position, each of the laser beams Lc is split into a plurality of laser beams Lv and focused by the action of the DOE 50.

[0073] It is preferable that the intensity of the laser light Lb passing through each condenser lens 81 is uniform. If the intensity varies, the energy at each condenser spot will change, which may result in variations in the processing of the hole H. For example, if the maximum value of the intensity of the laser light Lb passing through the multiple condenser lenses 81 that make up the condenser element array 80 is Emax and the minimum value is Emin, it is preferable that the following formula (2) is satisfied. (Emax-Emin) / (Emax+Emin)<0.1 ···(2)

[0074] In this embodiment as well, it is preferable that the number of branches of the laser light Lb by the condenser element array 80 is equal to or less than the number of spatial modes of the laser light Lb. In other words, it is preferable that the area of ​​each condenser lens 81 is larger than the area of ​​one coherence region of the laser light Lb.

[0075] 3.2 Operation The operation of the laser processing system 1b according to the second embodiment is similar to the operation of the laser processing system 1 according to the comparative example.

[0076] In this embodiment, the number of focused spots is the product of the number of branches by the focusing element array 80 and the number of divisions by the DOE 50. Specifically, in this embodiment, the laser beam Lb is branched into four laser beams Lc by the focusing element array 80, and each laser beam Lc is divided into multiple laser beams Lv by the DOE 50, so that four times as many focused spots as in the comparative example are formed on the surface 45a of the workpiece 45. As a result, in this embodiment, four times as many holes H as in the comparative example are simultaneously formed.

[0077] 3.3 Effects Each of the four laser beams Lc split by the focusing element array 80 has a reduced number of spatial modes, similar to when a portion of the laser beam Lb is extracted using an aperture or a slit. In this embodiment, the number of spatial modes of each of the four laser beams Lc is approximately ¼ that of the laser beam Lb. In this manner, in this embodiment, the number of spatial modes of the laser beam Lc is reduced, and therefore the number of spatial modes of each of the multiple laser beams Lv split by the DOE 50 is also reduced. This improves the beam quality of the laser beam Lv that forms the focused spot, thereby reducing the focused spot diameter and improving the processing speed and processing accuracy.

[0078] Furthermore, in this embodiment, since the same DOE 50 as in the comparative example can be used, the number of focused spots can be increased without fabricating a large-area DOE with a complex pattern. Therefore, according to this embodiment, even when a multimode laser beam is used, it is possible to increase the number of focused spots and improve the processing speed and processing accuracy.

[0079] 3.4 Simulation Next, a description will be given of a simulation carried out to confirm the effects of the laser processing system 1b according to the second embodiment. Fig. 10 shows the simulation results of the focused spots formed in the second embodiment.

[0080] In this simulation, laser light Lb having 9 spatial modes and a 3 × 3 spatial mode distribution was incident on the DOE 50. The area of ​​the elements 51 constituting the DOE 50 was set to approximately 1 / 64 times the cross-sectional area of ​​the incident laser light Lb.

[0081] In this simulation, the focusing element array 80 has a 4×4 configuration in which four focusing lenses 81 are arranged in the X direction and four in the Y direction. However, most of the laser light Lb incident on the focusing element array 80 is in the central 2×2 region of the focusing element array 80. The spatial mode number of the laser light Lb passing through each focusing lens 81 in the 2×2 region is approximately 2.25.

[0082] 11 shows the results of a simulation of the focused spot formed in the comparative example. The simulation was also performed under the same conditions for the comparative example.

[0083] 10 and 11, symbol P1 indicates the beam profile of laser light Lb incident on the DOE 50, and symbol P2 indicates the distribution of the focused spots on the surface 45a of the workpiece 45. As shown in Figures 10 and 11, in the comparative example, the focused spots have a rectangular shape and low beam quality, but in the second embodiment, the focused spots have a circular shape and the beam quality is improved.

[0084] 3.5 Variations Next, various modifications of the second embodiment will be described.

[0085] In the second embodiment, the focusing element array 80 is disposed downstream of the DOE 50, but the focusing element array 80 may be disposed upstream of the DOE 50. In this case, the laser beam Lb is split into four laser beams Lc by the focusing element array 80 and enters the DOE 50. The DOE 50 splits each of the four laser beams Lc into a plurality of laser beams Lv. Even in this case, the distance D between the DOE 50 and the focusing element array 80 is preferably set to the minimum value allowed by the structure. For example, the distance D is preferably 50 mm or less, and more preferably 25 mm or less.

[0086] Furthermore, in the second embodiment, a focusing element array 80 composed of a plurality of focusing lenses 81 is used, but as shown in FIG. 12, a focusing element array 80a composed of a plurality of DOEs 82 may also be used. The DOE 82 is a type of shaping DOE and focuses incident laser light Lb. The focusing element array 80a splits the incident laser light Lb into a plurality of laser light Lc with a reduced number of spatial modes. The DOE 82 is an example of a "focusing element" according to the technology of the present disclosure.

[0087] 4. Third embodiment A laser processing system 1c according to a third 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 description will be omitted unless otherwise specified.

[0088] 4.1 Configuration 13 is a schematic diagram showing the configuration of a laser processing system 1c according to the third embodiment. Except for the optical device 41, the laser processing system 1c has the same configuration as the laser processing system 1 according to the comparative example.

[0089] The laser processing system 1c differs from the laser processing system 1 according to the comparative example in that a deflection element array 90 is provided between the DOE 50 and the condenser lens 60 in the optical device 41. The deflection element array 90 functions as a branching optical element.

[0090] The deflection element array 90 is composed of two prisms 91. As shown in FIG. 14, the prism 91 is a deflection element that deflects incident light and outputs the deflected light. The two prisms 91 are arranged so that their deflection directions are different from each other. The prism 91 is an example of a "deflection element" according to the technology of the present disclosure.

[0091] In this embodiment, the deflection element array 90 is disposed downstream of the DOE 50. The distance between the DOE 50 and the deflection element array 90 is preferably set to the minimum value allowed by the structure. Furthermore, in this embodiment, the condenser lens 60 is disposed downstream of the deflection element array 90. The distance between the deflection element array 90 and the condenser lens 60 is preferably set to the minimum value allowed by the structure.

[0092] The laser beam Lb incident on the DOE 50 is not yet split immediately after being emitted from the DOE 50, and is split into a plurality of laser beams Lv as the diffracted waves emitted from the DOE 50 form an image at a distance. For this reason, the deflection element array 90 arranged close to the downstream side of the DOE 50 has the effect of splitting the laser beam Lb into two laser beams Lc that have different deflection directions and a reduced number of spatial modes.

[0093] The condenser lens 60 is disposed so as to condense each laser beam Lc branched by the deflection element array 90 onto the surface 45a of the workpiece 45. Furthermore, since the laser beams Lc incident on the condenser lens 60 travel in different directions, the condenser lens 60 condenses each laser beam Lc at a different position on the surface 45a. At the condensing position, each laser beam Lc is split into multiple laser beams Lv and condensed by the action of the DOE 50.

[0094] 4.2 Operation The operation of the laser processing system 1c according to the third embodiment is similar to the operation of the laser processing system 1 according to the comparative example.

[0095] In this embodiment, the number of focused spots is the product of the number of branches by the deflector array 90 and the number of divisions by the DOE 50. Specifically, in this embodiment, the laser beam Lb is branched into two laser beams Lc by the deflector array 90, and each laser beam Lc is divided into multiple laser beams Lv by the DOE 50, so that twice as many focused spots as in the comparative example are formed on the surface 45a of the workpiece 45. As a result, in this embodiment, twice as many holes H as in the comparative example are simultaneously formed.

[0096] 4.3 Effects Each of the two laser beams Lc split by the deflection element array 90 has a reduced number of spatial modes, similar to when a portion of the laser beam Lb is extracted using an aperture or a slit. In this embodiment, the number of spatial modes of each of the two laser beams Lc is approximately half that of the laser beam Lb. In this manner, in this embodiment, the number of spatial modes of the laser beam Lc is reduced, and therefore the number of spatial modes of each of the multiple laser beams Lv split by the DOE 50 is also reduced. This improves the beam quality of the laser beam Lv that forms the focused spot, thereby reducing the focused spot diameter and improving the processing speed and processing accuracy.

[0097] Furthermore, in this embodiment, since the same DOE 50 as in the comparative example can be used, the number of focused spots can be increased without fabricating a large-area DOE with a complex pattern. Therefore, according to this embodiment, even when a multimode laser beam is used, it is possible to increase the number of focused spots and improve the processing speed and processing accuracy.

[0098] Although the deflection element array 90 is disposed downstream of the DOE 50 in the third embodiment, the deflection element array 90 may be disposed upstream of the DOE 50. In this case, the laser beam Lb is split into two laser beams Lc by the deflection element array 90 and enters the DOE 50. The DOE 50 splits each of the four laser beams Lc into a plurality of laser beams Lv. Even in this case, it is preferable that the distance between the DOE 50 and the deflection element array 90 be the minimum value allowed by the structure.

[0099] In addition, in the third embodiment, the laser light Lb is split into two laser lights Lc by two prisms 91 that constitute the deflection element array 90, but the laser light Lb may be split into three or more laser lights Lc by three or more prisms 91.

[0100] In the third embodiment, the deflection element array 90 is configured by arranging a plurality of prisms 91, but may be configured by arranging DOEs 92 as shown in Fig. 15. The DOEs 92 are an example of the "deflection element" according to the technology of the present disclosure.

[0101] 5. Electronic Device Manufacturing Method The laser processing method according to each of the above embodiments can be applied to the formation of through holes in a substrate included in an interposer IP in the manufacture of the electronic device 100 described below.

[0102] Fig. 16 schematically shows the configuration of an electronic device 100. The electronic device 100 shown in Fig. 16 includes an integrated circuit chip IC, an interposer IP, and a circuit substrate CS. The integrated circuit chip IC is, for example, a chip in which an integrated circuit (not shown) is formed on a silicon substrate. The integrated circuit chip IC is provided with a plurality of bumps ICB that are electrically connected to the integrated circuit.

[0103] The interposer IP has an insulating substrate with a plurality of through holes (not shown), and a conductor (not shown) is provided in each through hole to electrically connect the front and back of the substrate. One surface of the interposer IP has a plurality of lands (not shown), each connected to a bump ICB, and each of the lands is electrically connected to one of the conductors in the through hole. The other surface of the interposer IP has a plurality of bumps IPB, and each of the bumps IPB is electrically connected to one of the conductors in the through hole.

[0104] A plurality of lands (not shown) are formed on one surface of the circuit board CS, and the circuit board CS is provided with a plurality of terminals that are electrically connected to the lands, respectively.

[0105] 17 shows a manufacturing method of the electronic device 100. First, in a first step SP1, laser processing and wiring formation are performed on the interposer substrate that constitutes the interposer IP. The laser processing of the interposer substrate includes forming through holes by irradiating the interposer substrate with pulsed laser light Out. The wiring formation includes forming a conductive film on the inner wall surface of the through holes formed in the interposer substrate. The interposer IP is produced in the first step SP1.

[0106] Next, in a second process SP2, the interposer IP and the integrated circuit chip IC are bonded together. The second process SP2 includes, for example, placing bumps ICB of the integrated circuit chip IC on lands of the interposer IP and electrically connecting the bumps ICB to the lands.

[0107] Then, in a third process SP3, the interposer IP and the circuit board CS are bonded together. The third process SP3 includes, for example, arranging the bumps IPB of the interposer IP on the lands of the circuit board CS and electrically connecting the bumps IPB and the lands.

[0108] The above description is intended to be illustrative rather than limiting. Thus, it will be apparent to those skilled in the art that modifications may be made to the embodiments of the present disclosure without departing from the scope of the appended claims.

[0109] Terms used throughout this specification and the appended claims should be interpreted as "open ended" terms. For example, the terms "include" or "including" should be interpreted as "not limited to what is stated as including." The term "having" should be interpreted as "not limited to what is stated as having." Additionally, the modifier "a" used in this specification and the appended claims should be interpreted as "at least one" or "one or more." Additionally, the term "at least one of A, B, and C" should be interpreted as "A," "B," "C," "A+B," "A+C," "B+C," or "A+B+C," and should also be interpreted as including combinations other than "A," "B," and "C."

Claims

1. a laser device that outputs laser light having two or more spatial modes; a branching optical element disposed on an optical path of the laser beam, which branches the laser beam into a plurality of branched beams having a reduced number of spatial modes; at least one segmented diffractive optical element that splits each of the plurality of split beams into a plurality of split beams on a surface of a workpiece; A laser processing system comprising:

2. 2. The laser processing system according to claim 1, The segmented diffractive optical element is constructed by repeatedly arranging elements on which a basic pattern is formed.

3. 3. The laser processing system according to claim 2, The length of the element is equal to or less than half the length of one coherence region of the laser light.

4. 2. The laser processing system according to claim 1, The branching optical element is a wedge plate that highly reflects part of the laser light.

5. 5. The laser processing system according to claim 4, The segmented diffractive optical element is disposed on the optical path of each of the plurality of split beams.

6. 6. The laser processing system according to claim 5, The optical system further includes a condenser lens disposed downstream of the divided diffractive optical element for condensing the divided light beams onto the surface of the workpiece.

7. 2. The laser processing system according to claim 1, The branching optical element is a light-collecting element array made up of a plurality of light-collecting elements, and is arranged downstream or upstream of the segmented diffractive optical element.

8. 8. The laser processing system according to claim 7, The focusing element is a focusing lens or a diffractive optical element.

9. 8. The laser processing system according to claim 7, The distance between the branching optical element and the segmented diffractive optical element is 50 mm or less.

10. 8. The laser processing system according to claim 7, The area of ​​the focusing element is larger than the area of ​​one coherence region of the laser light.

11. 8. The laser processing system according to claim 7, When the maximum value of the intensity of the laser light passing through the plurality of focusing elements is Emax and the minimum value is Emin, the relationship (Emax-Emin) / (Emax+Emin)<0.1 is satisfied.

12. 2. The laser processing system according to claim 1, The branching optical element is a deflection element array made up of a plurality of deflection elements, and is arranged downstream or upstream of the segmented diffractive optical element.

13. 13. The laser processing system according to claim 12, The deflection element is a prism or a diffractive optical element.

14. 2. The laser processing system according to claim 1, The number of branches of the laser light by the branching optical element is equal to or less than the number of spatial modes of the laser light.

15. A method for manufacturing an electronic device, comprising: a laser device that outputs laser light having two or more spatial modes; a branching optical element disposed on an optical path of the laser beam, which branches the laser beam into a plurality of branched beams having a reduced number of spatial modes; at least one segmented diffractive optical element that splits each of the plurality of split beams into a plurality of split beams on a surface of a workpiece; fabricating an interposer by laser processing the interposer substrate using a laser processing system including the coupling the interposer and the integrated circuit chip together to electrically connect them; The interposer and the circuit board are coupled to each other to electrically connect them together. A method for manufacturing an electronic device, comprising:

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