Laser processing system and method for manufacturing electronic device

Abstract

A laser processing system and a method of manufacturing an electronic device are provided. A laser processing system according to one aspect of the present disclosure is provided with: a laser device that outputs laser light having two or more spatial patterns; a branching optical element which is disposed on the optical path of the laser light and branches the laser light into a plurality of branched light beams having a reduced number of spatial modes; and at least one split-type diffractive optical element that splits each of the plurality of branched light beams into a plurality of split light beams on the surface of the workpiece.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a laser processing system and a method for manufacturing electronic devices. BACKGROUND

[0002] In recent years, in a semiconductor exposure apparatus, with miniaturization and high integration of semiconductor integrated circuits, improvement in resolution is required. Therefore, shortening of the wavelength of light emitted from an exposure light source is being promoted. For example, as a gas laser device for exposure, a KrF excimer laser device that outputs laser light having a wavelength of about 248.4 nm, and an ArF excimer laser device that outputs laser light having a wavelength of about 193.4 nm are used.

[0003] In addition, the pulse width of the excimer laser is about several tens of ns, and the wavelength is short, and thus the excimer laser is sometimes used for direct processing of a high molecular material, a glass material, and the like.

[0004] The chemical bond in the high molecular material can be cut by the excimer laser having a photon energy higher than the bond energy. Therefore, it is known that non-heating processing of the high molecular material can be performed using the excimer laser, and the processed shape is beautiful.

[0005] In addition, it is known that the absorption rate of glass, ceramic, and the like with respect to the excimer laser is high, and thus even a material that is difficult to process using visible and infrared laser light can be processed using the excimer laser.

[0006] Prior Art Documents

[0007] Patent Documents

[0008] [Patent Document 1] U.S. Patent Application Publication No. 2020 / 070280 Specification SUMMARY

[0009] The laser processing system of one aspect of the present disclosure includes: a laser device that outputs laser light having two or more spatial modes; a branch optical element that is disposed on an optical path of the laser light and branches the laser light into a plurality of branched lights having a reduced number of spatial modes; and at least one split-type diffractive optical element that splits each of the plurality of branched lights into a plurality of split lights on a surface of an object to be processed.

[0010] A manufacturing method of an electronic device of one aspect of the present disclosure includes the steps of: manufacturing an interposer by laser processing a substrate of the interposer with a laser processing system; joining and electrically connecting the interposer and an integrated circuit chip; and joining and electrically connecting the interposer and a circuit substrate, the laser processing system having: a laser device that outputs laser light having two or more spatial modes; a branch optical element that is disposed on an optical path of the laser light, branches the laser light into a plurality of branched lights having a reduced number of spatial modes; and at least one split-type diffractive optical element that splits the plurality of branched lights into a plurality of split lights, respectively, on a surface of a processed object. BRIEF DESCRIPTION OF DRAWINGS

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

[0012] Figure 1 is a diagram schematically showing a structure of a laser processing system of a comparative example.

[0013] Figure 2 is a diagram schematically showing a structure of a laser device.

[0014] Figure 3 is a diagram showing an example of an element constituting a DOE.

[0015] Figure 4 is a diagram showing an example of a DOE.

[0016] Figure 5 is a diagram showing a plurality of laser lights split by a DOE.

[0017] Figure 6 is a diagram showing an example of increasing the number of condensing points using a beam splitter.

[0018] Figure 7 is a diagram schematically showing a structure of a laser processing system of a first embodiment.

[0019] Figure 8 is a diagram schematically showing a structure of a laser processing system of a second embodiment.

[0020] Figure 9 is a diagram showing a structure example of a condensing element array.

[0021] Figure 10 is a diagram showing a simulation result of condensing points formed in the second embodiment.

[0022] Figure 11 is a diagram showing a simulation result of condensing points formed in the comparative example.

[0023] Figure 12 is a diagram showing a modification example of a condensing element array.

[0024] Figure 13 Fig. 1 is a diagram schematically showing a structure of a laser processing system of a first embodiment.

[0025] Figure 14 Fig. 2 is a diagram showing a deflection based on a prism.

[0026] Figure 15 Fig. 3 is a diagram showing a deflection based on a DOE.

[0027] Figure 16 Fig. 4 is a diagram schematically showing a structure of an electronic device.

[0028] Figure 17 Fig. 5 is a flowchart showing a manufacturing method of an electronic device. DETAILED DESCRIPTION

[0029] <Contents>

[0030] 1. Comparative Example

[0031] 1.1 Structure

[0032] 1.2 Action

[0033] 1.3 Diffractive Optical Element

[0034] 1.4 Subject

[0035] 2. First Embodiment

[0036] 2.1 Structure

[0037] 2.2 Action

[0038] 2.3 Effect

[0039] 3. Second Embodiment

[0040] 3.1 Structure

[0041] 3.2 Action

[0042] 3.3 Effect

[0043] 3.4 Simulation

[0044] 3.5 Modified Example

[0045] 4. Third Embodiment

[0046] 4.1 Structure

[0047] 4.2 Action

[0048] 4.3 Effect

[0049] 5. Manufacturing Method of Electronic Device

[0050] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. The embodiments described below represent several examples of the present disclosure and do not limit the present disclosure. In addition, the structures and actions described in each of the embodiments are not necessarily all essential to the structures and actions of the present disclosure. Furthermore, the same reference numerals are applied to the same constituent elements, and repetitive descriptions will be omitted.

[0051] 1. Comparative Example

[0052] 1.1 Structure

[0053] Figure 1 The structure of the laser processing system 1 of the comparative example is schematically shown. In addition, the so-called comparative example is a form that the applicant recognizes as known only to the applicant, and is not a publicly known example that the applicant himself recognizes.

[0054] The laser processing system 1 includes a laser device 2 and a laser processing device 4 as main structures. The laser processing system 1 is used for hole processing of forming holes such as through holes on a glass substrate for an interposer.

[0055] The laser device 2 is a laser device that outputs ultraviolet pulse laser. For example, the laser device 2 is a discharge excitation type laser device that outputs ultraviolet pulse laser with F2, ArF, KrF, XeCl, XeF, or the like as a laser medium. In the present disclosure, the laser device 2 is provided as a KrF excimer laser device that outputs ultraviolet pulse laser with a center wavelength of 248.4 nm. Hereinafter, the ultraviolet pulse laser output from the laser device 2 will be simply referred to as laser Lb.

[0056] The laser device 2 is connected to the laser processing device 4 through an optical path tube 5. The optical path tube 5 is disposed on an optical path of the laser Lb between an exit of the laser device 2 and an entrance of the laser processing device 4.

[0057] The laser processing device 4 includes a laser processing processor 40, an optical device 41, a frame 42, an XYZ stage 43, and a work table 44. The optical device 41 and the XYZ stage 43 are fixed to the frame 42.

[0058] The work table 44 supports a workpiece 45. The workpiece 45 is a processing target of hole processing. The workpiece 45 is a glass substrate for an interposer, for example, an alkali-free glass substrate. In addition, the workpiece 45 can also be a substrate formed of quartz glass, an organic material, single crystal silicon, ceramic, or the like. The workpiece 45 is formed with a plurality of holes H by so-called multi-hole processing.

[0059] The XYZ stage 43 supports a work table 44. The work table 44 is fixed with a workpiece 45 thereon. The XYZ stage 43 is capable of moving the work table 44 in an X direction, a Y direction, and a Z direction, and changes the position of the workpiece 45 by moving the work table 44. The X direction, the Y direction, and the Z direction are orthogonal to each other. The X direction and the Y direction are parallel to a surface 45a of the workpiece 45. The Z direction is orthogonal to the surface 45a. The XYZ stage 43 is a moving stage capable of moving the workpiece 45 in a direction orthogonal to the optical axis of the condenser lens 60.

[0060] The optical device 41 includes a housing 41a, high reflection mirrors 47a, 47b, 47c, an attenuator 49, a diffractive optical element (DOE) 50, and a condenser lens 60. Each of the components in the optical device 41 is fixed to a bracket not shown and disposed at a predetermined position in the housing 41a.

[0061] The high reflection mirror 47a is disposed to reflect the laser light Lb that has passed through the optical path tube 5, and the reflected laser light Lb is incident on the high reflection mirror 47b through the attenuator 49. The optical path tube 5 and the housing 41a are purged, for example, with a purge gas. The purge gas is nitrogen, an inert gas, or the like, and is a gas that hardly absorbs the laser light Lb.

[0062] 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 two partial reflection mirrors 49a, 49b and rotation stages 49c, 49d of these partial reflection mirrors, for example. The partial reflection mirrors 49a, 49b are optical devices whose transmittance changes according to the incident angle of the laser light Lb. The incident angle of the laser light Lb is adjusted by the rotation stages 49c, 49d.

[0063] The high reflection mirrors 47b, 47c are disposed to reflect the laser light Lb that has passed through the attenuator 49, and the reflected laser light Lb is incident on the DOE 50.

[0064] The DOE 50 is disposed on the optical path of the laser light Lb reflected by the high reflection mirror 47c. The DOE 50 divides the laser light Lb incident from the high reflection mirror 47c into a plurality of laser lights Lv having different emission angles by diffracting the laser light Lb. That is, the DOE 50 divides the laser light Lb into the X direction and the Y direction. Furthermore, in the present disclosure, dividing the incident laser light into a plurality of laser lights without reducing the number of spatial modes is referred to as "dividing".

[0065] The condenser lens 60 is configured to cause the plurality of laser beams Lv emitted from the DOE 50 to be incident and to have a focal plane on the surface 45a of the workpiece 45. The condenser lens 60 is, for example, an Fθ lens that condenses the plurality of laser beams Lv emitted from the DOE 50 respectively, and generates a multi-point pattern in which a plurality of condensed points are arranged in a lattice shape.

[0066] Figure 2 The structure of the laser device 2 is schematically shown. The laser device 2 includes an oscillator 20, a monitor module 30, a diaphragm 35, and a laser processor 38. The oscillator 20 includes a chamber 21, an optical resonator composed of a back mirror 25a and an output coupling mirror 25b, a charger 23, and a power supply unit (PPM: Pulsed Power Module) 22.

[0067] Windows 21a, 21b are provided in the chamber 21. A laser gas as a laser medium is enclosed in the chamber 21.

[0068] In addition, an opening is formed in the chamber 21, and an electrically insulating plate 26 in which a plurality of feedthroughs 26a are embedded is provided so as to plug the opening. The PPM 22 is disposed on the electrically insulating plate 26. A pair of discharge electrodes 27a, 27b as main electrodes and a ground plate 28 are disposed in the chamber 21. The discharge faces of the discharge electrodes 27a, 27b are rectangular.

[0069] In order to excite the laser medium by discharge, the discharge electrodes 27a, 27b are disposed so that the discharge faces thereof face each other. The face of the discharge electrode 27a on the side opposite to the discharge face is supported on the electrically insulating plate 26. The discharge electrode 27a is connected to the feedthrough 26a. The face of the discharge electrode 27b on the side opposite to the discharge face is supported on the ground plate 28.

[0070] The PPM 22 includes a switch 22a, a charging capacitor not shown, a pulse transformer, a magnetic compression circuit, and a peak capacitor. The peak capacitor is connected to the feedthrough 26a via a connection portion not shown. The charger 23 charges the charging capacitor based on a control from the laser processor 38.

[0071] The switch 22a is turned on / off by the laser processor 38. The laser processor 38 turns on the switch 22a in accordance with a light emission trigger Tr transmitted from the laser processing processor 40.

[0072] When the switch 22a is turned on, current flows from the charging capacitor to the primary side of the pulse transformer, and due to electromagnetic induction, reverse current flows to the secondary side of the pulse transformer. The magnetic compression circuit is connected to the secondary side of the pulse transformer, and compresses the pulse width of the current pulse. The peak capacitor is charged by this current pulse. When the voltage of the peak capacitor reaches the breakdown voltage of the laser gas, the laser gas between the discharge electrodes 27a, 27b generates a discharge to cause insulation breakdown. By this discharge, an amount of laser Lb corresponding to one pulse is generated.

[0073] The back mirror 25a is formed by applying a highly reflective film on a planar substrate. The output coupling mirror 25b is formed by applying a partially reflective film on a planar substrate. The cavity 21 is disposed between the back mirror 25a and the output coupling mirror 25b. The laser Lb generated in the cavity 21 is amplified by the optical resonator and output from the output coupling mirror 25b.

[0074] The monitoring module 30 includes a beam splitter 31 and a light sensor 32. The beam splitter 31 is disposed on the optical path of the laser Lb output from the output coupling mirror 25b, and reflects a portion of the laser Lb. The light sensor 32 is disposed at a position where the laser Lb reflected by the beam splitter 31 is incident. The light sensor 32 measures the pulse energy of the laser Lb, and transmits the measurement value to the laser processor 38.

[0075] The laser processor 38 changes the charging voltage of the charger 23 based on the measurement value of the pulse energy measured by the light sensor 32, thereby controlling so that the pulse energy of the laser Lb output from the laser device 2 becomes the target pulse energy Et.

[0076] The light shutter 35 is disposed on the optical path of the laser Lb transmitted through the beam splitter 31. The light shutter 35 is opened and closed according to the instruction from the laser processor 38. The laser processor 38 controls the output of the laser Lb from the laser device 2 by controlling the light shutter 35.

[0077] 1.2 Action

[0078] Next, the action of the comparative example laser processing system 1 will be described. First, the laser processing processor 40 controls the XYZ stage 43 so that the focal plane of the condensing lens 60 coincides with the surface 45a of the workpiece 45. 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 49 so that the fluence on the surface 45a becomes the target fluence Ft.

[0079] Here, the fluence refers to the pulse energy density per 1 pulse at one condensing point on the surface 45a of the workpiece 45. If the transmittance of the optical device 41 when the transmittance of the attenuator 49 is 100% is set to To, the number of condensing points is set to Q, and the area of the condensing point is set to S, the target fluence Ft is represented by the following formula (1).

[0080] Ft = Et x Ta x To / (Q x S)...(1)

[0081] When the laser processor 38 receives the target pulse energy Et, it controls the charger 23 so that the pulse energy of the laser Lb becomes the target pulse energy Et. Next, the laser processor 38 causes the oscillator 20 to naturally oscillate by inputting a trigger to the switch 22a. Also, at this time, the shutter 35 is in a closed state.

[0082] A part of the laser Lb output from the cavity 21 via the output coupling mirror 25b is sampled by the monitoring module 30, whereby the pulse energy is measured. The laser processor 38 controls the charger 23 so that the difference AE between the pulse energy and the target pulse energy Et approaches zero. Also, if the difference AE is within an allowable range, the laser processor 38 sends a permission signal to the laser processing processor 40, and sets the shutter 35 to an open state.

[0083] When the laser processing processor 40 receives the permission signal, it sends a light emission trigger Tr specifying the repetition frequency and the number of pulses to the laser device 2. As a result, the laser Lb is output from the laser device 2 in synchronization with the light emission trigger Tr, and is incident on the laser processing device 4 via the optical path tube 5. This laser Lb is reflected by the highly reflective mirror 47a, is attenuated by the attenuator 49, and is reflected by the highly reflective mirrors 47b and 47c. The laser Lb reflected by the highly reflective mirror 47c is incident on the DOE 50.

[0084] The DOE 50 divides the incident laser Lb into a plurality of lasers Lv on the surface 45a of the workpiece 45. The condenser lens 60 forms a multi-point pattern by condensing the plurality of lasers Lv on the surface 45a of the workpiece 45, respectively. By irradiating each condensing point of the multi-point pattern with the laser Lv of the specified number of pulses, laser ablation is generated to form a hole H.

[0085] Next, the laser processing processor 40 controls the XYZ stage 43 and the laser device 2 to repeatedly change and irradiate the irradiation position of the multi-point pattern in a step-and-repeat manner, whereby a plurality of holes H are formed in the entire processing region where hole processing is required.

[0086] 1.3 Diffractive optical element

[0087] Next, the DOE will be described. Generally, a DOE is roughly classified into a division type DOE that divides a beam into a plurality of beams, and a shaping type DOE that shapes the shape of a beam. The DOE 50 of the present disclosure is a division type DOE. The DOE 50 is manufactured by engraving a pattern on a substrate such as quartz.

[0088] Typically, it is difficult to fabricate large-area DOEs with a single pattern. For example, when generating patterns by computer, doubling the area of ​​the DOE requires four times the storage and computation time. Therefore, the smaller the DOE area, the easier it is to design and fabricate. However, reducing the DOE area decreases the overall numerical aperture of the optical system, leading to a reduction in resolution. Therefore, it is preferable to fabricate large-area DOEs by bonding elements forming the basic pattern into multiple tile-like structures. This helps to suppress the reduction in resolution.

[0089] Figure 3 An example of element 51 constituting DOE 50 is shown. Element 51 is a rectangular plate formed with a basic pattern.

[0090] Figure 4 An example of DOE50 is shown. DOE50 is constructed by bonding multiple elements 51 together in a tile-like shape. That is, DOE50 is constructed by repeatedly arranging elements 51. The basic pattern is designed to be continuous at the boundaries with adjacent basic patterns.

[0091] 1.4 Research Topic

[0092] Laser device 2 is capable of high output and high repeatability, making it suitable for multi-hole machining using DOE50. On the other hand, in hole machining, a higher beam quality of laser Lb is more advantageous in terms of machining speed and accuracy. However, since laser Lb is multi-mode, it has a large number of spatial modes, resulting in lower beam quality. Multi-mode refers to having two or more spatial modes. Spatial modes are modes perpendicular to the optical axis of the optical resonator, i.e., transverse modes. In the case of laser device 2 being an excimer laser, the number of spatial modes is approximately 10 to 1000.

[0093] like Figure 5 As shown, the number of spatial modes of the multiple lasers Lv after being divided by DOE50 is the same as that of the laser Lb incident on DOE50, and therefore they have the same quality as laser Lb. Therefore, in the comparative example laser processing system 1, because the beam quality of the laser Lb output from the laser device 2 is low, there is a problem that the focusing point diameter of the laser Lv focused by the focusing lens 60 becomes larger, resulting in reduced processing speed and processing accuracy.

[0094] Furthermore, in multi-hole processing, from a productivity standpoint, it is desirable to increase the number of focusing points in order to simultaneously form multiple holes H. However, in the comparative example laser processing system 1, increasing the number of focusing points leads to a problem where the pattern becomes more complex, making the design and fabrication of the DOE50 more difficult.

[0095] To increase the number of focusing points, such as Figure 6As shown, consider using a beam splitter BS to split the laser Lb into two lasers Lb, and then using a DOE50 to further divide each of the two split lasers Lb into multiple lasers Lv. The multiple lasers Lv resulting from each DOE50 are then focused by a condenser lens 60. Thus, the number of focusing points is doubled.

[0096] However, in Figure 6 In the structure shown, the number of spatial modes of the two lasers Lb after being split by the beam splitter BS is the same as that of the laser Lb incident on the beam splitter BS, resulting in low beam quality. Therefore, even when the number of focusing points is increased by using the beam splitter BS, there are still problems such as large focusing point diameter, reduced processing speed, and reduced processing accuracy.

[0097] This disclosure provides a laser processing system and a method for manufacturing electronic devices that can increase the number of focal points and improve processing speed and accuracy even when using multi-mode lasers (Lb).

[0098] 2. First Implementation Method

[0099] The laser processing system 1a according to the first embodiment of this disclosure will be described. Furthermore, structures identical to those described above will be labeled with the same reference numerals, and repeated descriptions will be omitted unless specifically stated otherwise.

[0100] 2.1 Structure

[0101] Figure 7 The structure of the laser processing system 1a according to the first embodiment is shown in a schematic diagram. Except for the optical device 41, the laser processing system 1a has the same structure as the laser processing system 1 of the comparative example.

[0102] In this embodiment, a wedge plate 70 is disposed within the optical device 41 in the optical path of the laser Lb incident on the high-reflectivity mirror 47c. For example, the wedge plate 70 is formed of synthetic quartz and has a high-reflectivity coating applied to its surface. The wedge plate 70 causes a portion of the laser Lb to be highly reflective, thereby branching the laser Lb into two lasers Lc with a reduced number of spatial modes. Preferably, the wedge plate 70 branches the laser Lb in such a way that the two lasers Lc each have an equal number of spatial modes. Furthermore, in this disclosure, the term "branching" refers to the process of causing the incident laser to become multiple lasers with a reduced number of spatial modes. The wedge plate 70 is an example of a "branching optical element" of the technology of this disclosure. Additionally, the laser Lc is an example of a "branched beam" of the technology of this disclosure.

[0103] Further, it is preferable that the wedge plate 70 be configured to divide the laser light Lb into directions corresponding to the discharge direction of the laser device 2. This is because the number of spatial modes of the laser light Lb in the directions corresponding to the discharge direction is large, and the beam quality in the directions corresponding to the discharge direction is low. In the optical path between the high reflector 47b and the high reflector 47c in which the wedge plate 70 is disposed, the Z direction corresponds to the discharge direction.

[0104] In the present embodiment, the DOE 50 and the condenser lens 60 are disposed on the optical paths of the two laser lights Lc each branched by the wedge plate 70. Specifically, the laser light Lb is branched into the laser light Lc reflected by the wedge plate 70 and the laser light Lc not reflected by the wedge plate 70 and incident on the high reflector 47c. The DOE 50 and the condenser lens 60 are disposed on the optical path of the laser light Lc reflected by the wedge plate 70 and the optical path of the laser light Lc not reflected by the wedge plate 70 and incident on the high reflector 47c and reflected by the high reflector 47c.

[0105] The structure of the DOE 50 and the condenser lens 60 is the same as that of the DOE 50 and the condenser lens 60 of the comparative example. In the present embodiment, the DOE 50 divides the incident laser light Lc into a plurality of laser lights Lv having different emission angles. The condenser lens 60 is configured to cause the plurality of laser lights Lv emitted from the DOE 50 to be incident and the focal plane to be located on the surface 45a of the workpiece 45. The laser light Lv is an example of the “divided light” of the technology of the present disclosure.

[0106] It is preferable that the length of the element 51 configuring the DOE 50 be 1 / 2 or less of the length of the coherent region of the laser light Lb.

[0107] In a case where the number of spatial modes of the laser light Lb is M, there are M coherent regions in the cross section of the laser light Lb, and the areas of the respective coherent regions are equal. Within one coherent region, the phases are consistent and spatially coherent. Between two coherent regions, the phases are inconsistent, and thus spatially incoherent.

[0108] 2.2 Action

[0109] The action of the laser processing system la of the first embodiment is the same as that of the laser processing system 1 of the comparative example.

[0110] In the present embodiment, the laser light Lb is branched by the wedge plate 70 into two laser lights Lc, and each laser light Lc is divided by the DOE 50 into a plurality of laser lights Lv, and thus twice the number of condensing points of the comparative example is formed on the surface 45a of the workpiece 45. Thus, in the present embodiment, twice the number of holes H of the comparative example is formed at the same time.

[0111] 2.3 Effects

[0112] As with the case where the two lasers Lc split by the wedge plate 70 each cut out a part of the laser Lb using an aperture or a slit, the number of spatial modes decreases. In the present embodiment, the number of spatial modes of each of the two lasers Lc is about 1 / 2 that of the laser Lb. In this way, in the present embodiment, since the number of spatial modes of the laser Lc incident on the DOE 50 decreases, the number of spatial modes of each of the plurality of lasers Lv split by the DOE 50 also decreases. Due to this, the beam quality of the laser Lv forming the focal point improves, and thus the focal point diameter becomes small, and the processing speed and the processing accuracy improve.

[0113] In addition, in the present embodiment, since the DOE 50 is disposed on the optical path of each of the two lasers Lc split by the wedge plate 70, the same DOE 50 as in the comparative example can be used. That is, according to the present embodiment, without making a large-area DOE having a complex pattern, it is possible to increase the number of focal points. Thus, according to the present embodiment, even in the case where a multi-mode laser is used, it is possible to increase the number of focal points, and improve the processing speed and the processing accuracy.

[0114] In addition, in the first embodiment, the laser Lb is split into two lasers Lc by one wedge plate 70, but it is also possible to split the laser Lb into three or more lasers Lc using two or more wedge plates 70. In this case, it is sufficient to dispose the DOE 50 and the condenser lens 60 on the optical path of each of the split lasers Lc. However, it is preferable that the number of splits be equal to or less than the number of spatial modes of the laser Lb. In other words, it is preferable that the beam cross-sectional area of each of the split lasers Lc be larger than the area of one coherence region of the laser Lb.

[0115] 3. Second Embodiment

[0116] A laser processing system lb of a second embodiment of the present disclosure will be described. Furthermore, the same reference signs are attached to structures identical to those described above, and the repeated description will be omitted except for the case where it is particularly described.

[0117] 3.1 Structure

[0118] Figure 8 The structure of the laser processing system lb of the second embodiment will be described schematically. The laser processing system lb is identical to the laser processing system 1 of the comparative example except for the optical device 41.

[0119] The laser processing system lb differs from the laser processing system 1 of the comparative example in that a condensing element array 80 is provided in place of the condenser lens 60 in the optical device 41. The condensing element array 80 functions as a splitting optical element.

[0120] As Figure 9As shown, the light collecting element array 80 is configured by arranging a plurality of light collecting lenses 81 in a matrix shape. For example, the light collecting element array 80 is arranged with two light collecting lenses 81 in each of the X direction and the Y direction. Note that the number of light collecting lenses 81 configuring the light collecting element array 80 can be appropriately changed. The light collecting lens 81 is an example of the "light collecting element" of the technology of the present disclosure.

[0121] In the present embodiment, the light collecting element array 80 is disposed on the downstream side 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 configuration. For example, the distance D is preferably 50 mm or less, and further preferably 25 mm or less.

[0122] The laser light Lb incident on the DOE 50 is not yet split after being emitted from the DOE 50, and is split into a plurality of laser lights Lv by the diffracted waves emitted from the DOE 50, which are imaged at a distance. Therefore, the light collecting element array 80 disposed on the downstream side of the DOE 50 has the effect of branching the laser light Lb into four laser lights Lc, which reduces the number of spatial modes. In the present embodiment, the light collecting element array 80 branches the laser light Lb into four laser lights Lc.

[0123] Further, each light collecting lens 81 configuring the light collecting element array 80 is disposed to collect each laser light Lc after branching on the surface 45a of the work 45. At the position of the light collection, each laser light Lc is split into a plurality of laser lights Lv by the effect of the DOE 50 and is collected.

[0124] It is preferable that the intensity of the laser light Lb passing through each light collecting lens 81 be uniform. This is because, if the intensity is deviated, the energy at each light collecting point varies, which can cause a processing deviation of the hole H. For example, in a case where the maximum value of the intensity of the laser light Lb passing through the plurality of light collecting lenses 81 configuring the light collecting element array 80 is set to Emax, and the minimum value is set to Emin, it is preferable to satisfy the following formula (2).

[0125] (Emax-Emin) / (Emax+Emin) < 0.1 ··· (2)

[0126] In the present embodiment, the number of branches of the laser light Lb by the light collecting element array 80 is also preferably equal to or less than the number of spatial modes of the laser light Lb. That is, it is preferable that the area of each light collecting lens 81 be larger than the area of one coherence region of the laser light Lb.

[0127] 3.2 Action

[0128] The action of the laser processing system lb of the second embodiment is the same as that of the laser processing system 1 of the comparative example.

[0129] In the present embodiment, the number of condensing points becomes the number obtained by multiplying the number of branches of the condensing element array 80 by the number of divisions of the DOE 50. Specifically, in the present embodiment, the laser Lb is branched into 4 lasers Lc by the condensing element array 80, and each of the lasers Lc is divided into a plurality of lasers Lv by the DOE 50, and thus 4 times the number of condensing points of the comparative example is formed on the surface 45a of the work 45. Thus, in the present embodiment, 4 times the number of holes H of the comparative example is formed at the same time.

[0130] 3.3 Effects

[0131] The number of spatial modes is reduced in the same manner as in the case where a portion of the laser Lb is cut out using an aperture or a slit, for each of the 4 lasers Lc branched by the condensing element array 80. In the present embodiment, the number of spatial modes for each of the 4 lasers Lc is about 1 / 4 times the number of spatial modes of the laser Lb. In this way, in the present embodiment, the number of spatial modes of the laser Lc is reduced, and thus the number of spatial modes of each of the plurality of lasers Lv divided by the DOE 50 is also reduced. Thus, the beam quality of the laser Lv forming the condensing point is improved, and thus the condensing point diameter is reduced, and the processing speed and the processing accuracy are improved.

[0132] In addition, in the present embodiment, since the same DOE 50 as in the comparative example can be used, it is possible to increase the number of condensing points without producing a large-area DOE having a complex pattern. Thus, according to the present embodiment, it is possible to increase the number of condensing points and improve the processing speed and the processing accuracy even in the case where a multi-mode laser is used.

[0133] 3.4 Simulation

[0134] Next, a simulation performed in order to confirm the effects of the laser processing system lb of the second embodiment will be described. Figure 10 A simulation result of the condensing points formed in the second embodiment is shown.

[0135] In the present simulation, a laser Lb having a spatial mode number of 9 and a spatial mode distribution of 3x3 was made incident on the DOE 50. In addition, the area of the element 51 constituting the DOE 50 was set to about 1 / 64 times the cross-sectional area of the incident laser Lb.

[0136] In addition, in the present simulation, a condensing element array 80 having a 4x4 structure in which 4 condensing lenses 81 are respectively arranged in the X direction and the Y direction was assumed. However, most of the laser Lb incident on the condensing element array 80 was located in a 2x2 region at the center of the condensing element array 80. The number of spatial modes of the laser Lb transmitted through each of the condensing lenses 81 in the 2x2 region was about 2.25.

[0137] Figure 11Analog results of the condensing points formed in the comparative example are shown. For the comparative example, the simulation was also performed under the same conditions.

[0138] In Figure 10 and Figure 11 , the symbol P1 represents the beam profile of the laser Lb incident to the DOE 50, and the symbol P2 represents the distribution of the condensing points on the surface 45a of the workpiece 45. As Figure 10 and Figure 11 indicate, it is known that in the comparative example, the shape of the condensing points is rectangular, and the beam quality is low, but in the second embodiment, the shape of the condensing points is circular, and the beam quality is improved.

[0139] 3.5 Modified Example

[0140] Next, various modified examples of the second embodiment will be described.

[0141] In the second embodiment, the condensing element array 80 is arranged on the downstream side of the DOE 50, but the condensing element array 80 can also be arranged on the upstream side of the DOE 50. In this case, the laser Lb is branched into four lasers Lc by the condensing element array 80 and is incident to the DOE 50. The DOE 50 divides the four lasers Lc into a plurality of lasers Lv, respectively. In this case, the distance D between the DOE 50 and the condensing element array 80 is also preferably set to the minimum value allowed by the configuration. For example, the distance D is preferably 50 mm or less, and further preferably 25 mm or less.

[0142] In addition, in the second embodiment, the condensing element array 80 composed of a plurality of condensing lenses 81 is used, but as Figure 12 indicates, a condensing element array 80a composed of a plurality of DOEs 82 can also be used. The DOE 82 is one of the shaped DOEs that condenses the incident laser Lb. The condensing element array 80a branches the incident laser Lb into a plurality of lasers Lc that are reduced in the number of spatial modes. The DOE 82 is an example of the "condensing element" of the technology of the present disclosure.

[0143] 4. Third Embodiment

[0144] A laser processing system 1c of a third embodiment of the present disclosure will be described. Furthermore, the same reference numerals are assigned to structures identical to those described above, and the repeated description is omitted except for the case where it is particularly described.

[0145] 4.1 Structure

[0146] Figure 13 The structure of the laser processing system 1c of the third embodiment is schematically shown. The laser processing system 1c is identical in structure to the laser processing system 1 of the comparative example except for the optical device 41.

[0147] The laser processing system 1c differs from the laser processing system 1 of the comparative example in that a deflection element array 90 is provided between the DOE 50 and the condenser lens 60 within the optical device 41. The deflection element array 90 functions as a branching optical element.

[0148] The deflection element array 90 is composed of two prisms 91. As shown in FIG. 6, the prisms 91 are deflection elements that deflect and emit incident light. The two prisms 91 are arranged so that the deflection directions thereof are different from each other. The prisms 91 are examples of the "deflection element" of the technology of the present disclosure. Figure 14

[0149] In the present embodiment, the deflection element array 90 is arranged on the downstream side 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 configuration. In the present embodiment, the condenser lens 60 is arranged on the downstream side 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 configuration.

[0150] The laser light Lb that is incident to the DOE 50 is not yet branched when it is emitted from the DOE 50, and is branched into a plurality of laser lights Lv by the diffracted waves emitted from the DOE 50. Therefore, the deflection element array 90 arranged close to the downstream side of the DOE 50 has the effect of branching the laser light Lb into two laser lights Lc having different deflection directions and a reduced number of spatial modes.

[0151] The condenser lens 60 is arranged so as to condense each of the laser lights Lc branched by the deflection element array 90 on the surface 45a of the workpiece 45. Further, since the traveling directions of the laser lights Lc incident to the condenser lens 60 are different, the condenser lens 60 condenses each of the laser lights Lc on a different position on the surface 45a. At the condensing position, each of the laser lights Lc is condensed while being branched into a plurality of laser lights Lv by the action of the DOE 50.

[0152] 4.2 Action

[0153] The action of the laser processing system 1c of the third embodiment is the same as that of the laser processing system 1 of the comparative example.

[0154] In the present embodiment, the number of condensing points becomes the number obtained by multiplying the number of branches of the deflection element array 90 by the number of branches of the DOE 50. Specifically, in the present embodiment, the laser light Lb is branched into two laser lights Lc by the deflection element array 90, and each of the laser lights Lc is branched into a plurality of laser lights Lv by the DOE 50, and thus the number of condensing points is twice the number of the comparative example. Thus, in the present embodiment, holes H are formed at twice the number of the comparative example.

[0155] 4.3 Effects​

[0156] Similar to the case where a portion of laser Lb is cut using an aperture or slit after branching from the deflection element array 90, the number of spatial modes for each of the two lasers Lc is reduced. In this embodiment, the number of spatial modes for each of the two lasers Lc is approximately half that of laser Lb. Thus, in this embodiment, the number of spatial modes for laser Lc is reduced, and therefore the number of spatial modes for each of the multiple lasers Lv segmented by DOE50 is also reduced. Consequently, the beam quality of the laser Lv forming the focusing point is improved, resulting in a smaller focusing point diameter and improved processing speed and accuracy.

[0157] Furthermore, in this embodiment, since the same DOE50 as in the comparative example can be used, it is possible to increase the number of focusing points without fabricating a large-area DOE with a complex pattern. Therefore, according to this embodiment, even when using a multi-mode laser, it is possible to increase the number of focusing points and improve processing speed and accuracy.

[0158] In the third embodiment, the deflection element array 90 is positioned downstream of the DOE 50, but it can also be positioned upstream of the DOE 50. In this case, the laser Lb is branched into two lasers Lc by the deflection element array 90 and incident on the DOE 50. The DOE 50 then divides each of the two lasers Lc into multiple lasers Lv. In this case, the distance between the DOE 50 and the deflection element array 90 is preferably set to the minimum structurally permissible value.

[0159] In addition, in the third embodiment, the laser Lb is branched into two lasers Lc by two prisms 91 constituting the deflection element array 90, but the laser Lb can also be branched into three or more lasers Lc by three or more prisms 91.

[0160] Furthermore, in the third embodiment, the deflection element array 90 is formed by arranging multiple prisms 91, but it can also be formed by arranging... Figure 15 It is constructed as shown in the figure. The DOE92 is an example of the "deflection element" of the technology disclosed herein.

[0161] 5. Manufacturing methods for electronic devices

[0162] The laser processing methods described in the above embodiments can be applied to the formation of through-holes in the substrate of the interposer IP in the manufacture of the electronic device 100 described below.

[0163] Figure 16 The structure of the electronic device 100 is shown schematically. Figure 16The electronic device 100 shown 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. A plurality of bumps ICB electrically connected to the integrated circuit are provided in the integrated circuit chip IC.

[0164] The interposer IP has an insulating substrate in which a plurality of through holes not shown are formed, and a conductor not shown electrically connecting the front and back surfaces of the substrate is provided in each of the through holes. A plurality of pads not shown connected to the bumps ICB are formed on one surface of the interposer IP, and each of the pads is electrically connected to any of the conductors in the through holes. A plurality of bumps IPB are provided on the other surface of the interposer IP, and each of the bumps IPB is electrically connected to any of the conductors in the through holes.

[0165] A plurality of pads not shown connected to the bumps IPB are formed on one surface of the circuit substrate CS. The circuit substrate CS has a plurality of terminals electrically connected to the pads, respectively.

[0166] Figure 17 A manufacturing method of the electronic device 100 is shown. First, in a first process SP1, laser processing and wiring formation of an interposer substrate constituting the interposer IP are performed. The laser processing of the interposer substrate includes forming a through hole by irradiating a pulsed laser to the interposer substrate. The wiring formation includes forming a conductive film on a wall surface inside the through hole formed in the interposer substrate. The interposer IP is manufactured by the first process SP1.

[0167] Next, in a second process SP2, the interposer IP is joined to the integrated circuit chip IC. The second process SP2 includes, for example, arranging the bumps ICB of the integrated circuit chip IC on the pads of the interposer IP, and electrically connecting the bumps ICB to the pads.

[0168] Then, in a third process SP3, the interposer IP is joined to the circuit substrate CS. The third process SP3 includes, for example, arranging the bumps IPB of the interposer IP on the pads of the circuit substrate CS, and electrically connecting the bumps IPB to the pads.

[0169] The above description is intended to be illustrative only and not limiting. Thus, it will be apparent to one skilled in the art that modifications can be made to the embodiments of the present disclosure without departing from the scope of the appended claims.

[0170] The terms used in the present specification and the appended claims should be interpreted as "non-limiting" terms. For example, the terms "comprise" or "include" should be interpreted as "not limited to the recited parts." The term "have" should be interpreted as "not limited to the recited parts." In addition, the phrase "one" recited in the present specification and the appended claims should be interpreted as "at least one" or "one or more." Furthermore, the term "at least one of A, B, and C" should be interpreted as "A," "B," "C," "A+B," "A+C," "B+C," or "A+B+C," and should also be interpreted as including combinations thereof with other than "A," "B," and "C."

Claims

1. A laser processing system, wherein, The laser processing system includes: A laser device that outputs laser light with two or more spatial modes; A branching optical element, which is arranged in the optical path of the laser, so that the laser is branched into multiple branched beams with a reduced number of spatial modes; as well as At least one segmented diffractive optical element that splits the plurality of branched beams into a plurality of segmented beams on the surface of the workpiece.

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

3. The laser processing system according to claim 2, wherein, The length of the element is less than half the length of a coherent region of the laser.

4. The laser processing system according to claim 1, wherein, The branching optical element is a wedge-shaped plate that makes a portion of the laser highly reflective.

5. The laser processing system according to claim 4, wherein, The segmented diffractive optical element is arranged on the optical path of each of the multiple branch beams.

6. The laser processing system according to claim 5, wherein, The laser processing system has a focusing lens disposed downstream of the segmented diffractive optical element, which focuses the multiple segmented beams onto the surface of the workpiece.

7. The laser processing system according to claim 1, wherein, The branched optical element is an array of focusing elements composed of multiple focusing elements, arranged on the downstream or upstream side of the segmented diffractive optical element.

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

9. The laser processing system according to claim 7, wherein, The distance between the branch optical element and the segmented diffractive optical element is less than 50 mm.

10. The laser processing system according to claim 7, wherein, The area of ​​the focusing element is larger than the area of ​​a coherent region of the laser.

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

12. The laser processing system according to claim 1, wherein, The branch optical element is a deflection element array consisting of multiple deflection elements, and is arranged on the downstream or upstream side of the segmented diffractive optical element.

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

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

15. A method for manufacturing an electronic device, wherein, The manufacturing method of the electronic device includes the following steps: Intermediate layer is fabricated by laser processing of the intermediate layer substrate using a laser processing system; The interposer is bonded to and electrically connected to the integrated circuit chip; and The interposer layer is bonded to the circuit board and electrically connected to it. The laser processing system includes: A laser device that outputs laser light with two or more spatial modes; A branching optical element, which is arranged in the optical path of the laser, so that the laser is branched into multiple branched beams with a reduced number of spatial modes; as well as At least one segmented diffractive optical element that splits the plurality of branched beams into a plurality of segmented beams on the surface of the workpiece.

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