CN107662055B - Laser processing method and laser processing device for brittle material substrate - Google Patents
Laser processing method and laser processing device for brittle material substrate Download PDFInfo
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- CN107662055B CN107662055B CN201710168587.0A CN201710168587A CN107662055B CN 107662055 B CN107662055 B CN 107662055B CN 201710168587 A CN201710168587 A CN 201710168587A CN 107662055 B CN107662055 B CN 107662055B
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- 238000000034 method Methods 0.000 claims description 31
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- 238000003754 machining Methods 0.000 description 30
- 230000015572 biosynthetic process Effects 0.000 description 17
- 230000000750 progressive effect Effects 0.000 description 16
- 238000010586 diagram Methods 0.000 description 8
- 238000005553 drilling Methods 0.000 description 8
- 239000011521 glass Substances 0.000 description 5
- 238000006073 displacement reaction Methods 0.000 description 3
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- 229910052594 sapphire Inorganic materials 0.000 description 2
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- 125000000449 nitro group Chemical class [O-][N+](*)=O 0.000 description 1
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K26/00—Working by laser beam, e.g. welding, cutting or boring
- B23K26/36—Removing material
- B23K26/38—Removing material by boring or cutting
- B23K26/382—Removing material by boring or cutting by boring
- B23K26/389—Removing material by boring or cutting by boring of fluid openings, e.g. nozzles, jets
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/70—Manufacture or treatment of devices consisting of a plurality of solid state components formed in or on a common substrate or of parts thereof; Manufacture of integrated circuit devices or of parts thereof
- H01L21/77—Manufacture or treatment of devices consisting of a plurality of solid state components or integrated circuits formed in, or on, a common substrate
- H01L21/78—Manufacture or treatment of devices consisting of a plurality of solid state components or integrated circuits formed in, or on, a common substrate with subsequent division of the substrate into plural individual devices
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K26/00—Working by laser beam, e.g. welding, cutting or boring
- B23K26/02—Positioning or observing the workpiece, e.g. with respect to the point of impact; Aligning, aiming or focusing the laser beam
- B23K26/04—Automatically aligning, aiming or focusing the laser beam, e.g. using the back-scattered light
- B23K26/046—Automatically focusing the laser beam
- B23K26/048—Automatically focusing the laser beam by controlling the distance between laser head and workpiece
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K26/00—Working by laser beam, e.g. welding, cutting or boring
- B23K26/36—Removing material
- B23K26/40—Removing material taking account of the properties of the material involved
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
- H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer
- H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic Table or AIIIBV compounds with or without impurities, e.g. doping materials
- H01L21/26—Bombardment with radiation
- H01L21/263—Bombardment with radiation with high-energy radiation
- H01L21/268—Bombardment with radiation with high-energy radiation using electromagnetic radiation, e.g. laser radiation
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/70—Manufacture or treatment of devices consisting of a plurality of solid state components formed in or on a common substrate or of parts thereof; Manufacture of integrated circuit devices or of parts thereof
- H01L21/71—Manufacture of specific parts of devices defined in group H01L21/70
- H01L21/768—Applying interconnections to be used for carrying current between separate components within a device comprising conductors and dielectrics
- H01L21/76801—Applying interconnections to be used for carrying current between separate components within a device comprising conductors and dielectrics characterised by the formation and the after-treatment of the dielectrics, e.g. smoothing
- H01L21/76802—Applying interconnections to be used for carrying current between separate components within a device comprising conductors and dielectrics characterised by the formation and the after-treatment of the dielectrics, e.g. smoothing by forming openings in dielectrics
- H01L21/76805—Applying interconnections to be used for carrying current between separate components within a device comprising conductors and dielectrics characterised by the formation and the after-treatment of the dielectrics, e.g. smoothing by forming openings in dielectrics the opening being a via or contact hole penetrating the underlying conductor
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
- H01S3/0007—Applications not otherwise provided for
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L2221/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof covered by H01L21/00
- H01L2221/10—Applying interconnections to be used for carrying current between separate components within a device
- H01L2221/1005—Formation and after-treatment of dielectrics
- H01L2221/1052—Formation of thin functional dielectric layers
- H01L2221/1057—Formation of thin functional dielectric layers in via holes or trenches
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Abstract
The invention provides a laser processing method of a brittle material substrate, which can reduce processing time while inhibiting thermal damage compared with the prior art. In forming a plurality of holes in a thickness direction from a surface of a brittle material substrate by irradiating a laser beam, the plurality of holes are gradually formed by repeating: the processing target portion is switched at one height position every time the irradiation of the laser beam at one height position of one processing target portion is finished, and the focal point of the laser beam is moved by a predetermined distance in the thickness direction from the surface of the brittle material substrate every time the irradiation of the laser beam at all the processing target portions at one height position is finished, and the focal point is set at a new height position.
Description
Technical Field
The present invention relates to a method for processing a brittle material substrate using a laser, and more particularly to processing a plurality of portions in a thickness direction.
Background
In the case of performing processing in the thickness direction (depth direction) such as drilling processing for forming a through hole or a non-through hole on a brittle material substrate represented by, for example, a glass substrate, a sapphire substrate, an alumina substrate, or the like, a laser is generally used as a processing means.
As one of such hole-drilling methods using a laser beam, a machining method is known in which a through-hole or a non-through-hole having a diameter larger than a beam spot diameter (beam diameter at a focal point, focused diameter) of the laser beam is formed by irradiating the laser beam concentrically (for example, see patent document 1).
Documents of the prior art
Patent document
Patent document 1: japanese patent laid-open publication No. 2013-146780
Problems to be solved by the invention
In the case where through-holes or non-through-holes are formed in a plurality of portions of a brittle material substrate in the thickness direction by laser, in the conventional technique, the through-holes or the non-through-holes are formed in this order. However, in the case of such a method, since the laser light is continuously irradiated to the same region until the formation of the hole is completed, there is a problem that thermal damage (generation of cracks or chips) is likely to occur in the vicinity of the region.
Further, when the depth of the hole to be formed is large, the brittle material substrate needs to be moved in the thickness direction every time the hole is formed, and therefore, there is a problem that processing time is required.
Disclosure of Invention
The present invention has been made in view of the above problems, and an object thereof is to provide a laser processing method for a brittle material substrate, which can reduce a processing time while suppressing thermal damage as compared with the prior art, when processing is performed in a thickness direction at a plurality of locations on the brittle material substrate.
Means for solving the problems
In order to solve the above-described problems, a first aspect of the present invention is a method for laser processing a brittle material substrate, in which a plurality of holes are formed in a thickness direction from a surface of the brittle material substrate by scanning a laser beam while irradiating the laser beam, the method comprising the steps of: the method includes the steps of switching a processing target portion at one height position of the processing target portion each time irradiation and scanning of a laser beam at the one height position are finished, and moving a focal point of the laser beam from a surface of the brittle material substrate in a thickness direction by a predetermined distance and setting the focal point at a new height position each time irradiation and scanning of the laser beam at all the processing target portions at the one height position are finished.
A second aspect of the invention is the laser processing method for a brittle material substrate according to the first aspect of the invention, characterized in that the output of the laser beam is increased every time the focal point is set at a new height position.
A third aspect of the invention is the laser processing method for a brittle material substrate according to the second aspect of the invention, wherein the plurality of holes are circular holes, and the laser beam is scanned at the processing target portion so that the focal point draws a concentric track.
A fourth aspect of the invention is the laser processing method of a brittle material substrate according to any one of the first to third aspects of the invention, characterized in that the laser beam is a picosecond UV laser or a picosecond green laser.
A fifth aspect of the present invention is a laser processing apparatus for processing a brittle material substrate with a laser beam, comprising: a table on which the brittle material substrate is placed and fixed; a light source that emits the laser beam; and a head that scans a brittle material substrate placed on the table while irradiating the brittle material substrate with the laser beam emitted from the light source, wherein the laser processing apparatus gradually forms the plurality of holes by repeating: the head portion switches the processing target portion at one height position every time irradiation and scanning of the laser beam at the one height position of the one processing target portion are finished, and the focal point of the laser beam is moved by a predetermined distance in the thickness direction from the surface of the brittle material substrate by relatively moving the table with respect to the head portion every time irradiation and scanning of the laser beam at all the processing target portions at the one height position are finished, thereby setting the focal point at a new height position.
A sixth aspect of the invention is the laser processing apparatus according to the fifth aspect of the invention, characterized in that the output of the laser beam emitted from the light source is increased every time the focal point is set at a new height position.
A seventh aspect of the invention is the laser processing apparatus according to the sixth aspect of the invention, wherein the plurality of holes are circular holes, and the head scans the laser beam at the processing target portion so that the focal point describes a concentric track.
An eighth aspect of the invention is the laser processing apparatus according to any one of the fifth to seventh aspects of the invention, characterized in that the laser beam is a picosecond UV laser or a picosecond green laser.
Effects of the invention
According to the first to eighth aspects of the invention, by performing the hole forming process in the thickness direction at a plurality of locations on the surface of the brittle material substrate by the progressive process of forming a plurality of holes in parallel, it is possible to suppress the thermal damage of the brittle material substrate and to shorten the processing time as compared with the case of performing the sequential process of forming the respective holes sequentially.
Drawings
Fig. 1 is a diagram schematically showing the structure of a laser processing apparatus 100.
Fig. 2 is a diagram for explaining a scanning method of the laser beam LB during the drilling.
Fig. 3 is a diagram for explaining a process of the sequential processing.
Fig. 4 is a diagram for explaining a process of the progressive machining.
Fig. 5 is an image taken from above the circular holes with respect to the glass substrate on which the plurality of circular holes are formed by the progressive machining and the sequential machining.
Detailed Description
[ overview of laser processing apparatus ]
Fig. 1 is a diagram schematically showing the configuration of a laser processing apparatus 100 used for processing a brittle material substrate W in the embodiment of the present invention. In general, the laser processing apparatus 100 is configured to apply a laser beam LB emitted from a light source 1 to a brittle material substrate W mounted on and fixed to a table 2, thereby performing a predetermined process on the brittle material substrate W.
Examples of the brittle material substrate W to be processed include a glass substrate, a sapphire substrate, and an alumina substrate.
The laser processing apparatus 100 mainly includes, in addition to the light source 1 and the table 2: a head 3 serving as a direct irradiation source of a laser beam LB to a brittle material substrate W; a shutter 4 attached to the light source 1 for turning on/off the emission of the laser beam LB from the light source 1; a reflecting mirror 5 that determines an optical path of the laser beam LB that reaches the head 3 by reflecting the laser beam LB emitted from the light source 1 at a predetermined angle; and a control unit 10 that controls operations of the respective units of the laser processing apparatus 100. In fig. 1, 2 mirrors 5 are provided, but this is merely an example, and the number and arrangement positions of the mirrors 5 are not limited to the embodiment shown in fig. 1.
The laser beam LB is appropriately selected according to the material of the brittle material substrate W to be processed, and is preferably a picosecond UV laser, a picosecond green laser, or the like. As the light source 1, a light source matching the laser beam LB used for processing may be used. The operation of the light source 1 for generating the laser beam LB and the on/off operation of the shutter 4 are controlled by a control unit 10.
The table 2 is a portion on which a brittle material substrate W is horizontally placed and fixed during processing. The table 2 is freely movable in the vertical direction by a drive mechanism 2 m. The driving mechanism 2m is controlled by the control unit 10, and thus the brittle material substrate W can be moved up and down in the thickness direction thereof during processing in the laser processing apparatus 100. The driving mechanism 2m may be provided so that the table 2 can be horizontally moved in the uniaxial direction or the biaxial direction, and further, may be provided so that at least the portion of the table 2 on which the brittle material substrate W is placed can be rotated in the horizontal plane. This enables the machining position to be appropriately adjusted and changed.
The brittle material substrate W may be fixed to the table 2 by various known methods. For example, the brittle material substrate W may be fixed by suction or may be fixed by clamping an end portion of the brittle material substrate W by a predetermined clamping means.
The head 3 has a galvanometer mirror (galvometer mirror)3a and an f θ lens 3 b. The galvanometer mirror 3a can emit the incident laser beam LB in an arbitrary direction within a predetermined range by controlling the posture thereof by the control unit 10. The f θ lens 3b is disposed above the table 2 so as to be horizontally disposed and to allow the laser beam LB emitted from the galvanometer mirror 3a to enter, and the laser beam LB emitted from the galvanometer mirror 3a passes through the f θ lens 3b to be irradiated from the vertical upper direction onto the brittle material substrate W horizontally placed and fixed on the table 2. Thus, in the laser processing apparatus 100, the irradiation position of the laser beam LB placed on the brittle material substrate W fixed to the table 2 can be continuously changed by continuously changing the posture of the galvanometer mirror 3a by the control of the control unit 10. That is, the brittle material substrate W can be scanned from above by the laser beam LB.
The irradiation range of the laser beam LB to the brittle material substrate W placed and fixed on the table 2 is predetermined in accordance with the size and posture change range of the galvanometer mirror 3 a. When the machining is performed outside such an irradiation-enabled range, the table 2 needs to be moved by the driving mechanism 2m to machine the new irradiation-enabled range.
Instead of providing the drive mechanism 2m on the table 2, a drive mechanism, not shown, may be provided on the head 3 to move the head 3 relative to the table 2.
The control unit 10 is realized by a general-purpose computer, for example. Various operations of the laser processing apparatus 100, such as emission of the laser beam LB from the light source 1, movement of the table 2, and posture change of the galvanometer mirror 3a, are realized by executing a control program, not shown, in the control unit 10.
[ outline of drilling processing ]
Next, an outline of the hole forming process according to the present embodiment performed on the brittle material substrate W by using the laser processing apparatus 100 described above will be described by taking a case where one portion is processed as an example. Fig. 2 is a diagram for explaining a scanning method of the laser beam LB in such drilling.
The following is envisaged in fig. 2: z-z 0 is the position of the front surface (upper surface) of the brittle material substrate W, and the irradiation position of the laser beam LB is changed from the position of z0 to z1 in the thickness direction (z direction) of the brittle material substrate W, whereby a substantially cylindrical non-through hole (circular hole) having a predetermined depth of the diameter D is formed in the thickness direction from the front surface of the brittle material substrate W. Here, the diameter D is a value larger than the diameter (beam spot diameter) D1 of the focal point (beam spot) F of the laser beam LB. However, in fig. 2, for convenience of illustration, the diameter D is shown below z-z 1, but hereinafter the diameter D is set to a value at z-z 0, which is the surface of the brittle material substrate W.
First, the height position of the table 2 on which the brittle material substrate W is mounted and fixed is adjusted so that the focal point F coincides with the surface (z — z0) of the brittle material substrate W, and the output of the laser beam LB from the light source 1 (hereinafter, referred to as laser output) is set to a predetermined value (initial value) E0. Then, by controlling the posture of the galvanometer mirror 3a, the laser beam LB is scanned so that the center C of the focal point F draws a plurality of concentric tracks having different diameters coaxial with the diameter D at z 0. In other words, while changing the diameter, a plurality of circling scans are performed. Hereinafter, the trajectory of the center C of the focal point F may be referred to as the trajectory of the laser beam LB.
In the case shown in fig. 2, the laser beam LB is scanned with the laser output E0 so that 4 concentric tracks TR1, TR2, TR3, and TR4 are drawn counterclockwise in this order from the outside. By such scanning, the vicinity of the surface of the brittle material substrate W is processed to form a concave portion. In addition, although 4 trajectories TR1, TR2, TR3, and TR4 are independently described in fig. 2, the output state of the laser beam LB may be maintained at a point of time when one round scan by the laser beam LB is substantially completed during actual processing, and the state may be directly transited to the next round scan.
After the scanning by the laser beam LB at z0 is completed in the above-described manner, the table 2 is raised by a predetermined distance Δ z, that is, after the position of the focal point F of the laser beam LB is shifted from z0 by a distance Δ z in the depth direction of the brittle material substrate W, the concentric scanning is performed as described above. In addition, the depth and the pitch Δ z of the previously formed recesses may also be inconsistent. Thereafter, the movement of the table 2 and the concentric scanning by the laser beam LB are repeated until the focal point F of the laser beam LB reaches the position z1, and the concentric scanning is performed at the position. In other words, a plurality of circling scans are performed concentrically at each height position. The values of Δ z and z1 are determined according to the material of the brittle material substrate W and the depth of the circular hole to be formed. In general, the position where z is equal to z1 is determined to be a shallower position than the position where the bottom of the circular hole is formed.
In this case, the laser output is gradually increased each time the height of the focal point F is changed. In the case shown in fig. 2, when the laser output (final value) at z-z 1 is set to E-E1 (> E0), the laser output is increased in stages from the initial value E-E0 to E-E1.
That is, in the drilling process described here, the laser beam LB is irradiated onto the brittle material substrate W sequentially and while increasing the laser output as the height position of the focal point F is farther from the surface of the brittle material substrate W in a plurality of positions discrete in the thickness direction by moving the height position of the focal point F a predetermined distance in the thickness direction from the surface of the brittle material substrate W.
Thus, the formation of the concave portion in the thickness direction of the brittle material substrate W progresses every time the concentric scanning of the laser beam LB is repeated at different depth positions, and finally a circular hole of a desired depth is formed.
Here, the maximum diameter (diameter of the trajectory TR 1) D2 of the scanning trajectory of the laser beam LB and the number of scanning trajectories (i.e., the number of times of scanning) may be experimentally or empirically determined in advance based on the diameter D of the circular hole to be formed, the beam spot diameter D1, and the posture change range of the galvanometer mirror 3 a. For example, if the diameter of the circular hole to be formed is 50 μm and the beam spot diameter d1 is 15 μm, the desired circular hole can be formed by performing 5 concentric scans with d2 equal to 30 μm.
The initial value E0 of the laser output may be determined experimentally or empirically in advance in accordance with a range of laser outputs in which the above-described recess can be formed but thermal damage (cracks, chips, etc.) is not caused around the recess. The initial value E0 determined in this case may be selected according to a range in which machining cannot be performed until a desired depth when machining is performed in the depth direction while keeping the value constant.
On the other hand, the final value E1 of the laser output may be experimentally or empirically determined in advance based on a range of laser outputs that can be processed to a target depth but cause thermal damage to the surface of the brittle material substrate W when the processing is performed while keeping the value constant from the surface of the brittle material substrate W. However, when the thickness of the brittle material substrate W is small, the processing may be performed while the laser output is constantly maintained at the initial value E0 (E1 — E0).
In fig. 2, a plurality of concentric circular scans are performed in order from the outside, but may be performed in order from the inside instead. Alternatively, the scanning order may be changed every time the depth position of the focal point F is changed.
In addition, in the case shown in fig. 2, the portion to be subjected to the circling scanning is also separated by the distance Δ z in the thickness direction by changing the height position of the focal point F by Δ z, but instead, a mode (helical scanning) may be adopted in which the height position of the focal point F is continuously changed and a plurality of circling scans corresponding to the above-described plurality of circling scans in the concentric circle shape are continuously performed while the focal point F is moved by the distance Δ z in the thickness direction. In such a case, the laser output may be continuously increased.
In the description so far, the case where the non-through-hole is formed is described as an example, but the same method can be used also in the case where the through-hole is formed. That is, when the total moving distance of the focal point F of the laser beam LB from the surface of the brittle material substrate W is sufficiently large, the through-hole can be formed. In this case, as in the case of forming the non-through hole, the specific processing conditions may be determined by the thickness of the brittle material substrate W, the irradiation conditions of the laser beam LB, and the like.
In the description so far, the description has been given of the form in which the circular hole is formed by performing the circular scanning of the laser beam LB, but when the diameter D of the circular hole to be formed is small, the circular scanning is not essential.
[ working of multiple holes ]
Next, a description will be given of processing for forming a plurality of holes in the thickness direction from the front surface of one brittle material substrate W by using the laser processing apparatus 100. Such a plurality of holes can be formed by simply forming each hole in sequence by the above-described method of drilling one portion (hereinafter referred to as sequential machining), but in the present embodiment, the plurality of holes are formed by a method called progressive machining. The progressive machining is a method of gradually forming a plurality of holes in parallel by switching the machining target portions each time the irradiation of the laser beam LB at one height position at one machining target portion is finished.
Fig. 3 is a diagram for explaining a process of the sequential processing. Now, consider a case where a plurality of circular holes (non-through holes) having a depth h are formed at a pitch p in the thickness direction of the brittle material substrate W. Further, the irradiation of the laser beam LB at one height position is set to be performed by the above-described circling scan. In fig. 3(a), adjacent 4 regions a, b, c, d in the predetermined formation region Ho of each circular hole are shown. In addition, in fig. 3, for convenience of illustration, only the formation planned regions Ho adjacent in one direction are shown, but in actual processing, the formation planned regions Ho may be determined two-dimensionally.
In the sequential processing, first, the focal point F of the laser beam LB is adjusted to the height of the surface of the brittle material substrate W (z is z0), and as shown in fig. 3b, concentric circular circling scanning and displacement of the height position of the focal point F of the laser beam LB are repeated for the region a as shown in fig. 2, thereby performing the hole drilling. Thus, when the circular hole Ha is formed in the region a as shown in fig. 3(c), concentric circular scanning and displacement of the height position of the focal point F of the laser beam LB are repeated in the region b in the same manner, and a circular hole Hb is formed in the region b as shown in fig. 3 (d). When the formation of the circular hole Hb is completed, if the processing is continued for all the formation-planned regions Ho in the order of the region c → the region d, a desired plurality of circular holes H (Ha, Hb, Hc, Hd) are finally formed in each of the formation-planned regions Ho (the regions a, b, c, d) as shown in fig. 3 (e).
On the other hand, fig. 4 is a diagram for explaining a progressive processing procedure adopted in the present embodiment. Now, as in the case of the sequential processing shown in fig. 3, a case where a plurality of circular holes (non-through holes) having a depth h are formed at a pitch p in the thickness direction of the brittle material substrate W will be considered. Also shown in fig. 4(a) are 4 adjacent regions a, b, c, d in the predetermined formation region Ho of each circular hole. Of course, in the case of progressive machining, the formation planned region Ho may be determined two-dimensionally.
First, as shown in fig. 4 b, after the focal point F of the laser beam LB is adjusted to the height of the surface of the brittle material substrate W (z: z0), the area a is set as an object, and then the laser beam LB is used to perform a circling scan. As a result, as shown in fig. 4(c), a recess is formed in the region a. Next, unlike the case of sequential processing, in progressive processing, a circling scan is performed on the region b while keeping the height position of the focal point F at z 0. As a result, as shown in fig. 4(d), a recess is formed in the region b following the region a. Then, the surrounding scan with the region c as the object is continued.
As shown in fig. 4 e, all the formation-planned regions Ho (in fig. 4, the regions a, b, c, and d) are subjected to the circling scan in a state where the height position of the focal point F is held at z0, and after the recess is formed in each region, the height position of the focal point F is shifted by the distance Δ z, and the region a is again subjected to the circling scan. This advances the formation of the recessed portions in the region a as shown in fig. 4 (f). When such surrounding scanning is finished, the surrounding scanning is continued for all the formation-planned regions Ho in the order of the region b → the region c → the region d without changing the height position of the focal point F, so that the formation of the concave portion in each region progresses. Thereafter, similarly, the displacement of the distance Δ z of the height position of the focal point F and the circling scan in the order of the region a → the region b → the region c → the region d are repeated until a predetermined position (z: z1) corresponding to the depth h of the predetermined circular hole. Finally, as shown in fig. 4 g, a plurality of desired circular holes H (Ha, Hb, Hc, Hd) are formed in each formation-planned region Ho (regions a, b, c, d).
If the above sequential processing is compared with the progressive processing, in the case of sequential processing, since the laser light is continuously irradiated to one formation planned region until the formation of the hole in the formation planned region is completed, the temperature rises near the region, and thermal damage (generation of cracks or chips) is likely to occur. In contrast, in the case of progressive machining, the machining time per one forming-planned region is short, and the forming-planned regions to be machined change one by one, so that it is difficult for a temperature rise to occur in each forming-planned region. Therefore, thermal damage (generation of cracks and chips) is less likely to occur.
In the case of sequential processing, each time processing is performed in each processing target region, the table 2 needs to be moved up and down to move the focal point F of the laser beam LB from the surface z of the brittle material substrate W to z0 to z1, whereas in the case of gradual processing, the focal point F is moved from the surface z0 to z1 only once intermittently during a period from the start of processing to the end of processing. This means that progressive machining can reduce the machining time compared to sequential machining. Further, such a time reduction effect becomes remarkable as the number of holes to be drilled increases.
As described above, according to the present embodiment, by performing the hole forming process in the thickness direction at a plurality of locations on the surface of the brittle material substrate W by the progressive process method in which a plurality of holes are formed in parallel, it is possible to suppress the thermal damage of the brittle material substrate and to shorten the processing time as compared with the case of the sequential process in which the holes are formed in sequence.
[ modified examples ]
In the above embodiment, the hole formation was described on the premise of a constant machining condition, but the machining condition may be changed at a point in time when the machining advances to an intermediate depth.
In the above-described embodiment, the description has been given of the case where the plurality of holes are formed by sequential machining, taking the machining of the circular hole as an example, but the application of the sequential machining to the formation of the plurality of holes can be applied to the case where the machining is performed in the depth direction in an arbitrary shape other than the circular hole. For example, the present invention can also be applied to formation of square holes or grooves. In the former case, the scanning of the laser beam LB at one height position may be performed by circular scanning so as to form coaxially rectangular tracks having different sizes, or may be performed by forming a plurality of parallel tracks at a predetermined pitch. In the latter case, a plurality of parallel tracks may be formed at a predetermined pitch.
[ examples ]
The plurality of round holes with the same shape are processed by adopting two modes of gradual processing and sequential processing.
Specifically, as the brittle material substrate W, a glass substrate (OA-10G manufactured by Japan electric Nitro) having a thickness of 0.1mm was prepared, and 9 circular holes having a diameter D of 1mm were formed in a 3X 3 square lattice shape with a pitch p of 1.5 mm. Further, as the laser beam LB, a picosecond UV laser is used. The specification of the picosecond UV laser is as follows.
Wavelength: 355 nm;
repetition frequency: 300 kHz;
and (3) outputting: initial value 1.5W → final value 1.5W;
scanning speed: 200 mm/s;
pulse energy: 5 mu J;
pulse energy density: 6.4J/cm2；
Pulse period: 0.67 μm;
pulse width: 50 ps.
Further, the beam spot diameter d1 of the laser beam LB was set to 10 μm, the maximum diameter d2 of the scanning locus of the laser beam LB was set to 1mm, the number of scans for one height position was set to 20, Δ z was set to 4 μm, and the moving distance (z1-z0) of the focal point F in the thickness direction was set to 36 μm.
Fig. 5 is an image of a glass substrate on which a plurality of circular holes are formed by each processing method, taken from above the circular holes. Fig. 5(a) is an image in the case of progressive processing, and fig. 5(b) is an image in the case of sequential processing.
By comparing the two images, cracks were observed at the portions indicated by the arrows in the image in the case of the sequential processing shown in fig. 5(b), but cracks were not observed in the image in the case of the progressive processing shown in fig. 5 (a).
Further, the machining time of each hole in the progressive machining was about 3.9 seconds, whereas the machining time of each hole in the sequential machining was about 4.4 seconds.
The above results show that progressive working is more excellent in suppression of thermal damage and shortening of working time than sequential working.
Description of the reference numerals
1: a light source;
2: a work table;
2 m: a drive mechanism;
3: a head portion;
3 a: a galvanometer mirror;
3 b: a lens;
4: an optical shutter;
5: a mirror;
10: a control unit;
100: a laser processing device;
c: the center of the focal point;
d: the diameter of the circular hole;
f: a focal point;
ho (a, b, c, d): a predetermined formation region (of the circular hole);
h (Ha, Hb, Hc, Hd): a circular hole;
LB: a laser beam;
w: a brittle material substrate;
d 1: the beam spot diameter;
h: depth (of the circular hole);
p: pitch (of the circular holes).
Claims (8)
1. A method of laser processing a brittle material substrate, in which a plurality of holes are formed in a thickness direction from a surface of the brittle material substrate by scanning a laser beam while irradiating the laser beam, the method being characterized in that,
gradually forming the plurality of holes by repeating: the method includes the steps of switching a processing target portion at one height position of the processing target portion each time irradiation and scanning of a laser beam at the one height position are finished, and moving a focal point of the laser beam from a surface of the brittle material substrate in a thickness direction by a predetermined distance and setting the focal point at a new height position each time irradiation and scanning of the laser beam at all the processing target portions at the one height position are finished.
2. The laser processing method of a brittle material substrate as claimed in claim 1, characterized in that,
increasing the output of the laser beam each time the focal point is set at a new height position.
3. The laser processing method of a brittle material substrate as claimed in claim 2, characterized in that,
the plurality of holes are round holes,
the laser beam is scanned at the processing target portion such that the focal point describes a concentric track.
4. The laser processing method of a brittle material substrate as claimed in any of claims 1 to 3, characterized in that,
the laser beam is picosecond UV laser or picosecond green laser.
5. A laser processing apparatus for processing a brittle material substrate by a laser beam, comprising:
a table on which the brittle material substrate is placed and fixed;
a light source that emits the laser beam; and
a head that scans a brittle material substrate placed on the stage while irradiating the laser beam emitted from the light source,
the laser processing apparatus gradually forms a plurality of holes by repeating: the head portion switches the processing target portion at one height position every time irradiation and scanning of the laser beam at the one height position of the one processing target portion are finished, and the focal point of the laser beam is moved by a predetermined distance in the thickness direction from the surface of the brittle material substrate by relatively moving the table with respect to the head portion every time irradiation and scanning of the laser beam at all the processing target portions at the one height position are finished, thereby setting the focal point at a new height position.
6. Laser processing apparatus according to claim 5,
increasing an output of the laser beam emitted from the light source every time the focal point is set at a new height position.
7. Laser processing apparatus according to claim 6,
the plurality of holes are round holes,
the head scans the laser beam at the processing target portion such that the focal point describes a concentric track.
8. Laser processing apparatus according to any of claims 5 to 7,
the laser beam is picosecond UV laser or picosecond green laser.
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| JP2016-149303 | 2016-07-29 | ||
| JP2016149303A JP6813168B2 (en) | 2016-07-29 | 2016-07-29 | Laser processing method and laser processing equipment for brittle material substrates |
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| JP (1) | JP6813168B2 (en) |
| KR (1) | KR102353478B1 (en) |
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| TW202400349A (en) | 2018-10-08 | 2024-01-01 | 美商伊雷克托科學工業股份有限公司 | Methods for forming a through-via in a substrate |
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Also Published As
| Publication number | Publication date |
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| KR20180013679A (en) | 2018-02-07 |
| JP2018015795A (en) | 2018-02-01 |
| TWI725137B (en) | 2021-04-21 |
| JP6813168B2 (en) | 2021-01-13 |
| TW201803677A (en) | 2018-02-01 |
| KR102353478B1 (en) | 2022-01-21 |
| CN107662055A (en) | 2018-02-06 |
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