JP6512935B2 - Laser processing method and laser processing apparatus - Google Patents

Description

  The present invention relates to a laser processing method and a laser processing apparatus, and more particularly to prevention of generation of cracks during processing.

  In recent years, with the diversification of information needs and the digitization of information, the speeding up of information communication devices is rapidly promoted. In the metal wiring conventionally used, there is a limit to speeding up. Therefore, attention is focused on optical interconnections which are excellent in both transmission speed and transmission distance and consume less power. A data transmission system using optical interconnection is configured by a signal transmission IC (Integrated Circuit), a printed circuit board, a connection medium such as a cable, and a signal reception IC. Since the design rules of the wiring are different between the IC and the circuit board, an interposer for connecting the circuit board to an optical device such as a signal transmission IC or a signal reception IC is required.

  As a substrate material of an interposer used in optical interconnection, glass has attracted attention as an interposer for high-speed transmission because it has high transparency and is less expensive than silicon.

  Flip chip mounting is often used to connect the optical device and the interposer. The flip chip mounting is excellent in high frequency transmission characteristics because the wiring length is short and the parasitic parameter is small as compared with the connection by wire bonding using a wire. In flip chip mounting, the light emitting and receiving surface of the device is arranged so as to face the substrate by light, which is a so-called face down, so the positional accuracy of the optical path of the optical signal is the positional accuracy of the mounting pad of the interposer in the planar direction. It depends heavily. In addition, since flip chip mounting is performed under high temperature, the smaller the difference between the thermal expansion coefficients of the optical device and the interposer, the smaller the residual stress.

  Therefore, glass such as borosilicate glass, which has a small difference in thermal expansion coefficient from silicon or compound semiconductors such as gallium arsenide and gallium nitride, which are the substrate materials that make up optical devices, has attracted attention as interposers for high-speed communication. It is rising.

  A light emitting element such as a surface emitting laser has a large thermal resistance, and heat generation by energization has a large influence on the element characteristics, so a heat dissipation mechanism is required, and further, as the high density mounting progresses, the mounting area is effectively utilized at maximum There is a need to. From the above point of view, as an interposer for high-speed transmission, wiring layers are formed on both the front surface side and the back surface side, and the high precision of through holes connecting these wiring lines increases the speed and integration of optical interconnections. Is essential to

  Therefore, miniaturization of through holes and improvement of position accuracy are major factors in determining the performance of the high speed transmission interposer. On the other hand, as described above, since the glass substrate used for the high speed transmission interposer has many chances of high temperature, such as heat generation at the time of use of the light emitting element, that is, at the time of energization, processing heat at the time of mounting It is necessary to supply in a low distortion state.

  A laser is used to form through holes in the glass substrate. The greatest problem in laser processing on glass substrates is the occurrence of stress strain or cracks. As a method of preventing the occurrence of a crack on a glass substrate at the time of laser processing, for example, the technology of Patent Document 1 is disclosed. Patent Document 1 discloses a technique of performing laser irradiation on a workpiece in water. It is effective to prevent the impact on such fragile materials by using water.

  In addition, in Patent Document 2, in order to prevent irregular reflection of laser light, a laser beam is transmitted to the laser light irradiation head, and a boundary passing plate which forms a boundary wall that contacts the cooling liquid and separates the cooling liquid from the atmosphere. The technology to provide is disclosed. The technique of Patent Document 2 can prevent irregular reflection at the interface between the air and the coolant, in addition to preventing the occurrence of cracks due to cooling.

JP-A-61-206587 Japanese Patent Application Laid-Open No. 7-256479

  However, although the technology of Patent Document 1 can prevent the occurrence of cracks in the glass substrate during laser processing, the high speed communication interposer requires high processing accuracy including positioning with high accuracy. For some reason, practical application was difficult due to fluctuation or refraction of laser light in water.

  Further, in the technology of Patent Document 2, although irregular reflection at the interface between the air and the coolant can be prevented in addition to the prevention of cracking due to cooling, a large-scale laser irradiation head is required and it is difficult to use for mass production. there were. In addition, there is also a problem that it is difficult to carry out laser processing while transporting a workpiece.

  The present invention has been made in view of the above, and it is an object of the present invention to provide a laser processing method capable of preventing generation of stress and achieving crack-free high quality laser processing while maintaining processing accuracy. To aim.

In order to solve the problems described above and to achieve the object, the present invention comprises the steps of: applying a hydrophilic treatment to a workpiece to be a glass substrate and covering the surface of the workpiece with a cooling film; The laser beam is scanned by the galvano scanner by cooperative control while conveying the workpiece at a constant speed, and the workpiece is irradiated with the laser beam through the cooling film, and the through hole is formed in the region to be irradiated with the laser beam. And b.

  According to the present invention, it is possible to obtain a laser processing method capable of preventing generation of stress and realizing crack-free high quality laser processing while maintaining positional accuracy.

The figure which shows typically the laser processing method concerning Embodiment 1. The figure which shows the glass interposer formed by the laser processing method concerning Embodiment 1. The figure which shows the laser processing apparatus of Embodiment 1. (A) to (e) are process cross sections showing the manufacturing process of the glass interposer using the laser processing method of Embodiment 1. Flow chart showing the manufacturing process of the glass interposer The figure which shows the memory apparatus using the glass interposer formed using the laser processing method of Embodiment 1. The figure which shows typically the laser processing method concerning Embodiment 2. The figure which shows the relationship between the position of the glass substrate in the laser processing method concerning Embodiment 2, and the conveyance speed of a glass substrate. (A) to (e) are process cross sections showing the manufacturing steps of the glass interposer using the laser processing method of the third embodiment. (A) to (e) are process cross sections showing the manufacturing steps of the glass interposer using the laser processing method of the fourth embodiment. A diagram schematically showing a laser processing method according to a fifth embodiment

  Hereinafter, a laser processing method and a laser processing apparatus according to an embodiment of the present invention will be described in detail based on the drawings. Note that the present invention is not limited by these embodiments, and various changes can be made without departing from the scope of the invention. Further, in the drawings shown below, the scale of each layer or each member may be different from the actual scale for easy understanding, and the same applies to the respective drawings. In addition, even cross sections may not be hatched in order to make the drawings easier to see.

Embodiment 1
FIG. 1 is a view schematically showing a laser processing method according to a first embodiment of the present invention. FIG. 2 is a view showing a glass interposer formed by the laser processing method according to the first embodiment. FIG. 3 is a diagram showing the laser processing apparatus of the first embodiment. FIGS. 4 (a) to 4 (e) are process cross-sectional views showing steps of manufacturing a glass interposer using the laser processing method of Embodiment 1, and FIG. 5 is a flowchart showing steps of manufacturing the glass interposer. FIG. 6 is a view showing a memory device using a glass interposer formed by using the process laser processing method of the first embodiment. In the laser processing method according to the first embodiment, the step of covering the surface of the glass substrate 11 to be processed with the hydrophilic film 21 as a cooling film, and the glass substrate 11 coated with the hydrophilic film 21 are transported at a constant speed. While performing cooperative control, scanning is performed by a galvano scanner, laser irradiation is performed, and the through holes 12 are formed in the glass substrate 11 via the hydrophilic film 21.

  In the laser processing method of the first embodiment, in order to prevent the occurrence of a crack when processing the glass substrate 11, the hydrophilic film 21 covers the vicinity of the formation region of the through hole 12 which is the processing hole. In the laser processing step, in order to prevent the surface of the hydrophilic film 21 on the laser incident side from being wavy, the laser light is scanned and condensed using an optical system such as galvano scanners 33X, 33Y, and Fθ lens 36. Process Then, in order to minimize the surface tension on the surface of the glass substrate 11, the hydrophilic film 21 is provided on the glass substrate 11 in advance. The film thickness of the hydrophilic film 21 should be as thin as possible in order to prevent positional deviation due to the refraction of laser light, and in order to suppress the temperature rise due to the irradiation energy of the laser, it is desirable to increase the heat capacity.

  The glass interposer 10 obtained by the laser processing method according to the first embodiment has a glass substrate 11 and a through hole 12 which is arranged on the glass substrate 11 to form a through hole, as shown in the cross sectional view of FIG. The first electrode 13 and the second electrode 14 formed on the main surface 11A and the second main surface 11B are provided. In the through hole 12, a through electrode 15 made of a conductive member is formed, which electrically connects the first electrode 13 and the second electrode 14. A current path is formed in the thickness direction of the glass substrate 11 by the through electrodes 15 formed in the through holes 12 penetrating the glass substrate 11, and the wiring length can be shortened, and high density and low resistance mounting can be achieved. To be realized.

  As shown in FIG. 3, the laser processing apparatus 1 includes a laser processing unit 30 that performs laser processing, and a processing control device 34 that controls a processing position and processing timing. The details will be described later.

  Next, a method of manufacturing the glass interposer 10 using the laser processing method according to the first embodiment will be described with reference to process cross-sectional views of FIGS. 4A to 4E and a flowchart of manufacturing steps of FIG.

  First, as shown in FIG. 4A, the glass substrate 11 is prepared, the manufacturing process is started in the start step S100, and the glass substrate 11 is cleaned by the usual method in the cleaning step S101.

  Next, as shown in FIG. 4B, the glass substrate 11 is subjected to a hydrophilic treatment in a hydrophilic treatment step S102 to form a hydrophilic film 21 on the surface.

  The cleaning of the glass substrate 11 and the formation of the hydrophilic film 21 will be described. The method of Embodiment 1 includes the cleaning step performed in step S101 and the hydrophilic film formation step performed in step S102.

Prior to the formation of the hydrophilic film 21, the glass substrate 11 is first cleaned. In the cleaning step of step S101, first, phosphorus glass etching is performed, and a solution containing HF such as hydrofluoric acid (HF) or mixed acid of HF with nitric acid (HNO ₃ ) and sulfuric acid (H ₂ SO ₄ ) is used as an etching solution. The wet etching process used removes the phosphorus glass layer adhering to the surface. The concentration of hydrofluoric acid in the solution containing HF is not particularly limited. Moreover, what is necessary is just to set the immersion time of the glass substrate 11 to the etching liquid which is a solution containing HF suitably according to various conditions.

In the phosphorus glass etching step, for example, the glass substrate 11 is immersed in the HF solution prepared in HF: H ₂ O = 1: 10 for 450 seconds to deposit deposits such as a phosphorus glass layer formed on the surface of the glass substrate 11. Etch away.

  Then, after performing phosphorus glass etching, pure water is supplied to the surface of the glass substrate 11 to clean the solution containing HF remaining on the surface of the glass substrate 11 with pure water. In the cleaning step, for example, the glass substrate 11 is immersed in pure water, and the HF solution remaining on the surface of the glass substrate 11 is washed away by cleaning.

  The surface of the glass substrate 11 after cleaning is hydrophobic because it is immersed in an HF solution. Therefore, after carrying out the cleaning step, the silicon oxide film is uniformly formed on the surface of the glass substrate 11 by wet oxidation treatment by supplying an oxidizing chemical having an oxidizing action to the surface of the glass substrate 11. Hydrophilic treatment to uniformly hydrophilize the surface of Examples of the oxidizing chemical solution include ozone water in which ozone gas is dissolved and hydrogen peroxide water.

  In the hydrophilic treatment step, after cleaning with pure water, for example, the glass substrate 11 is immersed in a storage tank where an oxidizing chemical solution is stored, thereby uniformly forming the hydrophilic film 21 which is an oxide film on the surface of the glass substrate 11 Then, the surface of the glass substrate 11 is uniformly hydrophilized.

  For example, ozone water in which ozone gas is dissolved is used as the oxidizing chemical solution. Then, after immersing the glass substrate 11 in the storage tank in which the ozone water is stored, the ozone water whose dissolved ozone concentration is adjusted to a predetermined concentration is constantly supplied to the storage tank to dissolve the dissolved ozone concentration of the ozone water in the storage tank. Keep it constant. The dissolved ozone concentration of the ozone water may be 0.1 mg / L or more, and as the concentration is higher, the hydrophilization treatment can be performed in a short time. The dissolved ozone concentration of the ozone water is more preferably 1 mg / L or more. In addition, the upper limit of the dissolved ozone concentration of ozone water is 180 mg / L from the viewpoint of the reason for production of high concentration ozone water. When the dissolved ozone concentration of the ozone water is about 0.1 mg / L, the immersion time of the glass substrate 11 in the ozone water may be 30 seconds or more. That is, the surface of the glass substrate 11 may be in a hydrophilic state as a whole and in a completely wet state, as long as a uniform water film is formed.

  Then, as shown in FIG. 4C, in the glass substrate 11 having the hydrophilic film 21 on the first main surface 11A, which is the surface, the step of forming the through holes 12 using the laser processing apparatus 1 of FIG. In S103, while performing positioning, through holes 12 are sequentially formed along the direction d by laser irradiation. At the time of laser irradiation, the surface of the glass substrate 11 is covered with the hydrophilic film 21, and the uniform thin hydrophilic film 21 is formed, so that the positional deviation due to the refraction of the laser light does not occur, and high precision is achieved. Fine through holes 12 can be formed at high density. In addition, by forming a uniform thin hydrophilic film, a reliable cooling effect can be obtained against the heat at the time of laser irradiation, and the residue of the laser irradiation from the formed through holes 12 is made hydrophilic. It can flow out with the membrane 21. It is preferable to be thick in order to obtain a cooling effect, but it is desirable to be thin in order to prevent deviation of the optical path due to refraction during laser irradiation. Here, the thickness of the hydrophilic film 21 is 20 nm or more and 1 mm or less.

  Laser irradiation is sequentially performed to form the through holes 12 on the glass substrate 11 as shown in FIG. 4 (d). After the through holes 12 are formed, a thin strike plating layer is formed on the entire surface by strike plating step S104 on the electrode formation region and the through holes 12 and patterned to form the first main surface 11A and the second main surface 11B. A strike plating layer pattern that covers the electrode formation region and the inside of the through hole 12 is formed.

  Finally, as shown in FIG. 4E, in the solder plating step S105, a solder plating layer is formed on the electrode formation region and the through hole 12 on which the strike plating layer pattern has been formed, and the first major surface 11A and A solder plating layer covering the inside of the through hole 12 is formed from the second major surface 11B, and the first electrode 13, the second electrode 14 and the through electrode 15 are formed. The glass interposer 10 is completed as described above.

  When hydrophilic film 21 remains on the surface, a low concentration acidic solution is applied to the surface of glass substrate 11 to remove hydrophilic film 21 prior to the plating step after formation of through holes 12. A cleaning step of spraying or spraying an inert gas containing a reducing gas may be added. In the washing step, the hydrophilic film 21 is removed together with the residue by laser processing, and a clean surface can be obtained. Also, the hydrophilic film 21 may remain on the surface of the completed glass interposer 10, as long as the plating layer can be selectively formed in the through holes 12 which are formed by laser irradiation and the hydrophilic film 21 is burnt away, It is also useful to form a device while leaving the hydrophilic film 21 as a passivation film without removing it.

  As shown in FIG. 6, as the memory device 100 is shown, the CPU 16 and the memory 17 which is a storage unit are stacked and mounted on the first main surface 10A of the glass interposer 10. Then, a ball grid array consisting of solder balls 18 is formed on the second main surface 10B of the glass interposer 10, and the glass interposer 10 is mounted on the wiring pattern 19P of the printed board 19 via the ball grid array. Complete.

Next, the laser processing unit 30 of the laser processing apparatus 1 used in the laser processing method of the first embodiment will be described. The laser processing unit 30 can transfer the laser beam oscillated from the laser oscillator 32 in cooperation control with the substrate mounting table 31 as a transfer unit and the substrate mounting table 31 capable of transferring the glass substrate 11 in the XYZ directions within the processing area. Galvano scanners 33X and 33Y scan in the X and Y directions. The galvano scanners 33X and 33Y rotate the galvano mirrors 35X and 35Y by the processing control device 34, thereby scanning laser light in the processing area in the X direction and the Y direction. Here, the laser oscillator 32 uses a CO ₂ laser.

  The Galvano mirrors 35X and 35Y are configured using mirrors having mirror surfaces of substantially elliptical shapes, and reflect the laser light 37 and deflect it to a predetermined angle. The galvano mirror 35X deflects the laser beam 37 in the X direction, and the galvano mirror 35Y deflects the laser beam 37 in the Y direction.

  The Fθ lens 36 is a focusing lens having telecentricity. The Fθ lens 36 deflects the laser beam 37 in a direction perpendicular to the first major surface 11A of the glass substrate 11 to be processed, and at the processing position of the glass substrate 11, that is, the through hole formation position. Focus. Thus, the Fθ lens 36 aligns the direction of the chief ray of the laser light 37 in the Z direction perpendicular to the XY plane.

  While the glass substrate 11 which is a to-be-processed object is mounted, the substrate mounting base 31 which is an XY table moves in the XY plane by the drive of the X-axis motor and the Y-axis motor which are not illustrated. Thereby, the substrate mounting table 31 moves the glass substrate 11 in the in-plane direction, that is, the X direction and the Y direction.

  The processing control device 34 is connected to each element of the laser processing unit 30 such as the laser oscillator 32 and the galvano scanners 33X and 33Y, and controls the laser oscillator 32 and the laser processing unit 30. When laser processing the glass substrate 11, the processing control device 34 instructs the laser oscillator 32 and the laser processing unit 30 on the laser processing conditions set in the processing program. The laser processing conditions here include the pulse emission timing of the laser light 37, the laser irradiation position, and the like.

  The processing control device 34 is configured by a computer or the like, and controls the laser oscillator 32 or the laser processing unit 30 by control such as NC (Numerical Control) control. The processing control device 34 includes a central processing unit (CPU), a read only memory (ROM), a random access memory (RAM), and the like. When the processing control device 34 controls the laser oscillator 32 or the laser processing unit 30, the CPU reads the processing program stored in the ROM by the input from the input unit (not shown) by the user, and the program in the RAM Deploy to storage area and execute various processing. Various data generated in various processes are temporarily stored in a data storage area formed in the RAM. Thus, the processing control device 34 controls the laser oscillator 32 and the laser processing unit 30.

  The area within which laser processing can be performed by the operation of the galvano mechanism, that is, the galvano scanners 33X and 33Y, and the galvano mirrors 35X and 35Y without moving the substrate mounting table 31, that is, the scannable area is the galvano area or scan area. In the laser processing apparatus 1, the substrate mounting table 31 is moved in the XY plane, and then the laser beam 37 is two-dimensionally scanned by the galvano scanners 33X and 33Y. The substrate mounting table 31, which is an XY table, moves in order so that the centers of the galvano areas are directly below the center of the Fθ lens 36, that is, the galvano origin.

  The galvano mechanism operates so that each hole position set in the galvano area becomes the irradiation position of the laser beam 37 in order. When the laser processing apparatus 1 performs the laser processing on the glass substrate 11, the galvano scanner 33X rotates the galvano mirror 35X, and the galvano mirror 35X reflects the laser light 37 sent from the laser oscillator 32. The galvano mirror 35X changes the traveling direction of the laser beam 37 by rotating. The rotational speed of the galvano mirror 35X or 35Y is controlled so that the hydrophilic film 21 on the surface of the glass substrate 11 on the laser incident side is not waved, while moving the glass substrate 11 at a constant speed, the galvano scanner 33X or 33Y Laser processing is performed by coordinated coordination control. If the rotational speed of the galvano mirror 35X or 35Y is constant with respect to the transport speed of the glass substrate 11, that is, if the acceleration does not have an acceleration, the hydrophilic film 21 does not wave and the stationary state is obtained. Since this can be maintained, highly accurate position control can be performed without causing variations in the laser irradiation position.

  Furthermore, the galvano scanner 33Y rotates the galvano mirror 35Y, and the galvano mirror 35Y reflects the laser beam 37 sent from the galvano mirror 35X. The galvano mirror 35 Y changes the traveling direction of the laser beam 37 by rotating. Thereby, the galvano mirrors 35X and 35Y move the irradiation area of the laser beam 37 in the in-plane direction of the glass substrate 11, that is, the XY direction.

  In the laser processing apparatus 1, the movement between the galvano areas by the substrate mounting table 31 and the two-dimensional scanning of the laser light 37 in the galvano area by the galvano mechanism are sequentially performed on the glass substrate 11 which is a workpiece. Go. Thereby, all the processing positions on the glass substrate 11 are laser processed.

  The distance D1 between the tip portion on the Fθ lens 36 side and the Fθ lens 36 in the tip portion of the galvano mirror 35X becomes narrow with the Fθ lens 36 having a short focal length. The distance D1 between the tip of the Fθ lens 36 and the Fθ lens 36 is, for example, 10 mm or less. The Galvano scanner 33X according to the present embodiment has a structural member such as a bearing because the Galvano scanner 33X is configured without arranging a structural member such as a bearing on the tip end side of the Galvano mirror 35X to prevent sideways vibration such as bearings. The galvano scanner 33 X can be mounted on the laser processing apparatus 1 without interference with the Fθ lens 36. As described above, even with the Fθ lens 36 having a short focal length, the Galvano scanners 33X and 33Y can be mounted on the laser processing apparatus 1 so that the Galvano mirror 35X is not inclined. It becomes possible to perform processing with high accuracy.

  As described above, highly accurate fine through holes 12 can be formed at high density without causing positional deviation due to refraction of laser light. In addition, since a uniform thin thin hydrophilic film 21 is formed, a cooling effect can be obtained, and a residue due to laser irradiation can flow out together with the hydrophilic film 21 from the formed through hole 12. . Therefore, according to the laser processing method of the first embodiment, it is possible to realize high quality laser processing without stress distortion, and hence crackless, with respect to the glass substrate 11 while maintaining the positional accuracy, so that high reliability can be achieved. It is possible to obtain a glass interposer 10 provided with a highly conductive wiring circuit.

The formation of the hydrophilic film 21 is not limited to the method of the first embodiment, and the cleaning with ozone water in the hydrophilic film formation step S102 by the hydrophilic treatment is carried out using sulfuric acid hydrogen peroxide: H ₂ SO ₄ It is possible to replace SPM washing with + H ₂ O ₂ and HPM washing with hydrogen peroxide: HCl + H ₂ O ₂ + H ₂ O.

Here, as the SPM cleaning solution, for example, a mixed solution of 80 wt% of sulfuric acid (H ₂ SO ₄ ) +5 wt% of hydrogen peroxide water (H ₂ O ₂ ) + H ₂ O can be used. Further, as the HPM cleaning solution, for example, a mixed solution of 10 wt% of hydrochloric acid (HCl) +5 wt% of hydrogen peroxide (H ₂ O ₂ ) + H ₂ O) can be used.

  Although the coolant supply unit is not illustrated in the first embodiment, it can be considered that the solution tank for forming the hydrophilic film 21 corresponds to the coolant supply unit.

Second Embodiment
FIG. 7 is a view schematically showing a laser processing method according to a second embodiment of the present invention. In the first embodiment, the laser irradiation is performed by forming the hydrophilic film 21 on the surface of the glass substrate 11. However, in the second embodiment, the laser 22 is supplied from the nozzle 23 as a coolant supply unit. Irradiation is performed to form the through holes 12. The laser processing unit 30 is the same as that of the first embodiment, and thus the description thereof is omitted here.

  In the laser processing method of the first embodiment, in order to prevent stress strain or crack generation at the time of processing the glass substrate 11, the hydrophilic film 21 covers the vicinity of the formation region of the through hole 12 which is a processing hole. In the second laser processing method, laser irradiation is performed while supplying the coolant 22 to the surface of the glass substrate 11. In the second embodiment, in order to prevent the surface of the coolant 22 on the laser incident side from being wavy, the laser beam 37 is scanned and condensed using an optical system such as the galvano scanners 33X and 33Y and the Fθ lens 36. Process. Then, the surface tension on the surface of the glass substrate 11 is minimized, and water as the coolant 22 is allowed to flow at a constant speed.

  In the second embodiment, as in the first embodiment, the laser processing unit 30 for performing laser processing, and a processing control device for controlling the processing position and processing timing, although not shown, is provided. The device 1 is used.

  The laser processing method is also the same as the laser processing method of the first embodiment except that it starts from the laser irradiation step in FIG. 4C and step S103 in FIG.

  The laser processing apparatus 1 of FIG. 3 is applied to the glass substrate 11 while supplying water as the coolant 22 to the first major surface 11A, which is the surface, instead of the hydrophilic film 21 shown in FIG. 4C. In step S103 of forming through holes by laser irradiation, the through holes 12 are sequentially formed by laser irradiation. At the time of laser irradiation, a uniform thin water film is formed on the surface of the glass substrate 11, so that highly accurate fine through holes 12 can be made in high density without causing positional deviation due to refraction of laser light. It can be formed. In addition, since a uniform thin water film is formed, a cooling effect can be obtained, and residues formed by laser irradiation can flow out together with the water film from the formed through holes 12.

  The laser irradiation scanned by the rotation of the galvano mirror 35X or 35Y keeps the glass substrate 11 moving at a constant speed so that the coolant 22 on the surface of the glass substrate 11 on the laser incident side does not wave, the galvano scanner The laser beam is scanned at the target position with high precision and coordinated with the coordinated control, and processing is advanced. FIG. 8 is a view showing the relationship between the position of the glass substrate 11 and the transport speed of the glass substrate 11 by driving of the substrate mounting table 31. As shown in FIG. The horizontal axis is the position of the glass substrate 11 in the X direction, and the vertical axis is the transport speed. The laser irradiation is performed in a laser irradiation area R where the rotational speed of the galvano mirror 35X or 35Y has a constant speed with respect to the transport speed of the glass substrate 11, that is, an area without acceleration. If the acceleration does not occur, the stationary state can be maintained without the coolant 22 waving, so that the position control with high accuracy can be performed without variation in the formation position of the through hole by the laser irradiation. Can.

  Laser irradiation is sequentially performed, and the through holes 12 are formed on the glass substrate 11 in the same manner as shown in FIG. 4 (d). After the through holes 12 are formed, a thin strike plating layer is formed on the entire surface by strike plating step S104 on the electrode formation region and the through holes 12 and patterned to form the first main surface 11A and the second main surface 11B. A strike plating layer pattern that covers the electrode formation region and the inside of the through hole 12 is formed.

  Finally, in the same manner as shown in FIG. 4E, in the solder plating step S105, a solder plating layer is formed in the electrode formation region in which the strike plating layer pattern is formed and the through holes 12, and the first main A solder plating layer covering the inside of the through hole 12 is formed from the surface 11A and the second major surface 11B, and the first electrode 13, the second electrode 14 and the through electrode 15 are formed. The glass interposer 10 is completed as described above.

  Also according to the laser processing method of the second embodiment, the laser irradiation is performed while cooling while maintaining the positional accuracy, thereby realizing high quality laser processing without stress distortion and crackless for the glass substrate. Thus, it is possible to obtain a glass interposer provided with a highly accurate and reliable wiring circuit.

  The thickness of the water film as a coolant is preferably large to obtain a cooling effect, but it is desirable to be thin to prevent deviation of the optical path due to refraction during laser irradiation. Here, the thickness of water as a coolant is 20 nm or more and 1 mm or less.

  In the second embodiment, laser processing is performed while supplying water as a coolant, but in addition to water, a liquid having a large heat capacity, alcohol, or the like is also applicable. The cooling effect can be enhanced without forming a thick liquid layer by using a coolant such as alcohol with a phase transition and performing laser irradiation while removing the heat of vaporization from the laser irradiation region.

Third Embodiment
FIGS. 9A to 9E schematically show a laser processing method according to the third embodiment of the present invention. In the third embodiment, a pattern of the gel coolant 24 is selectively formed in the laser irradiation area R _L on the surface of the glass substrate 11 and laser irradiation is performed to target the pattern of the gel coolant 24. .

  As in the first and second embodiments, the third embodiment also includes the laser processing unit 30 that performs laser processing, and a processing control device that controls the processing position and processing timing although not shown. A laser processing apparatus 1 is used.

  The laser processing method is also the same as in Embodiment 1, but first, as shown in FIG. 9A, the glass substrate 11 is prepared, and the glass substrate 11 is cleaned by a common method.

Next, as shown in FIG. 9B, a gel supply nozzle is used to selectively form a gel-like coolant 24 pattern on the laser irradiation area R _L on the surface of the glass substrate 11. It is desirable to use a high precision gel supply nozzle to increase the pattern accuracy of the gel coolant 24. Also, the pattern of the gel coolant 24 may be colored so that it can be used as the alignment pattern in the laser irradiation step so that it can be distinguished from the surface of the glass substrate 11.

Next, as shown in FIG. 9C, the gel processing apparatus 1 of FIG. 3 is used to apply gel to the glass substrate 11 on which the pattern of the gel coolant 24 is formed on the first main surface 11A that is the surface. The through holes 12 are sequentially formed along the direction d by laser irradiation while performing positioning toward the coolant 24. At the time of laser irradiation, the laser irradiation area R _{L on the} surface of the glass substrate 11 is covered with the gel coolant 24, and while the gel coolant 24 is evaporated, the laser irradiation is performed to make fine through holes 12 with high precision. It can be formed at high density. In addition, the pattern of the gel coolant 24 can be laser irradiated and evaporated to obtain a cooling effect, and the residue by the laser irradiation flows out of the formed through holes 12 together with the gel coolant 24. be able to.

  Laser irradiation is sequentially performed to form the through holes 12 on the glass substrate 11 as shown in FIG. After forming the through holes 12, a thin strike plating layer is formed on the entire surface by strike plating step S104 on the electrodes and through holes 12 and patterned to form electrodes from the first main surface 11A and the second main surface 11B. A strike plating layer pattern covering the area and the inside of the through hole 12 is formed.

  Finally, as shown in FIG. 9E, in the solder plating step S105, a solder plating layer is formed on the electrode formation region and the through hole 12 in which the strike plating layer pattern has been formed, and the first major surface 11A and A solder plating layer covering the inside of the through hole 12 is formed from the second major surface 11B, and the first electrode 13, the second electrode 14 and the through electrode 15 are formed. The glass interposer 10 is completed as described above.

  According to the method of the third embodiment, the laser irradiation is performed while evaporating the gel coolant 24 formed in a pattern, and the cooling effect can be obtained, and the residue by the laser irradiation from the formed through hole 12 Together with the gel coolant 24 can flow out. Therefore, according to the laser processing method of the third embodiment, it is possible to form fine through holes 12 with high precision without stress distortion, and with high density without cracks.

Fourth Embodiment
10 (a) to 10 (e) are cross-sectional views showing steps of manufacturing the glass interposer using the laser processing method according to the fourth embodiment of the present invention. In the fourth embodiment, first, the shallow groove 12S is formed by laser irradiation in the laser irradiation region R _L of the surface of the glass substrate 11, the shallow groove 12S is filled with the coolant 25, and the pattern of the coolant 25 is selectively selected. The laser irradiation is performed by targeting the pattern of the coolant 25.

  Also in the fourth embodiment, as in the first to third embodiments, the laser processing apparatus 1 is equipped with the laser processing unit 30 that performs laser processing and the processing control device 34 that controls the processing position and processing timing. Use.

  The laser processing method is also the same as in Embodiment 1, but first, as shown in FIG. 10A, the glass substrate 11 is prepared, and the glass substrate 11 is washed by a usual method.

Next, as shown in FIG. 10B, laser irradiation is performed on the laser irradiation region R _L of the surface of the glass substrate 11 using the laser processing apparatus 1 to form a pattern of shallow grooves 12S.

Next, as shown in FIG. 10C, a pattern of the coolant 25 is selectively formed in the shallow groove 12S formed in the laser irradiation area R _L on the surface of the glass substrate 11 using a supply nozzle not shown. . In addition, it is desirable that the pattern of the coolant 25 be colored so that it can be used as an alignment pattern in the laser irradiation step so as to be distinguishable from the surface of the glass substrate 11.

Next, as shown in FIG. 10 (d), the glass substrate 11 having the coolant 25 formed on the first main surface 11A, which is the surface, is directed to the coolant 25 using the laser processing apparatus 1 of FIG. The through holes 12 are sequentially formed by laser irradiation while performing positioning. At the time of laser irradiation, the laser irradiation area R _{L on the} surface of the glass substrate 11 is covered with the coolant 25, and while the coolant 25 is evaporated, the laser irradiation is performed to form the fine through holes 12 with high density at high density. can do. Further, the pattern of the coolant 25 is laser-irradiated and evaporated, whereby the cooling effect can be obtained, and the residue of the laser irradiation can be made to flow out together with the coolant 25 from the formed through holes 12.

  Laser irradiation is sequentially performed to form the through holes 12 on the glass substrate 11 as shown in FIG. After the through holes 12 are formed, a thin strike plating layer is formed on the entire surface by strike plating step S104 on the electrode formation region and the through holes 12 and patterned to form the first main surface 11A and the second main surface 11B. A strike plating layer pattern that covers the electrode formation region and the inside of the through hole 12 is formed.

  Finally, as shown in FIG. 10 (e), in the solder plating step S105, a solder plating layer is formed on the electrode formation region and the through hole 12 in which the strike plating layer pattern is formed, and the first major surface 11A and A solder plating layer covering the inside of the through hole 12 is formed from the second major surface 11B, and the first electrode 13, the second electrode 14 and the through electrode 15 are formed. The glass interposer 10 is completed as described above.

  According to the method of the fourth embodiment, the laser irradiation is performed while evaporating the coolant 25 formed in the shape of a pattern in the shallow groove 12S formed by the laser irradiation, so that the cooling effect can be obtained and formed. The residue of the laser irradiation can flow out of the through hole 12 together with the coolant 25. Therefore, according to the laser processing method of the fourth embodiment, fine through holes 12 with high accuracy can be formed at high density.

  Since the coolant used in the fourth embodiment is filled in the shallow groove 12S, it can be easily patterned by liquid supply from the nozzle, and a mask for patterning is not necessary, but it is used in the third embodiment. The use of a gel coolant facilitates handling.

  In addition, according to the method of the fourth embodiment, a through hole is formed by two steps of laser irradiation, in which formation of the shallow groove by laser irradiation and formation of the through hole by laser irradiation while positioning in the shallow groove are actually performed. Form Therefore, the depth of laser irradiation per one time can be made shallow, and furthermore, the through holes can be formed efficiently by using the pattern that combines the cooling function and the pattern for alignment for alignment. It is possible to form a through hole with high stress ratio and high aspect ratio without stress distortion, and hence without crack.

Embodiment 5
FIG. 11 is a view schematically showing a laser processing method and a laser processing apparatus according to a fifth embodiment of the present invention. In the fifth embodiment, first, in the method of forming the through holes 12 in the laser irradiation area R _L by laser irradiation while supplying the coolant to the surface of the glass substrate 11, the cooling liquid 40 filled in the cooling tank 40 is used. The substrate mounting table 31 is installed in water, the frame 41 for storing the liquid is installed on the substrate mounting table 31, and the laser corresponding to the height h of the frame 41 is held on the surface of the glass substrate 11. Irradiation is performed.

  The substrate mounting table 31 of the conveyance part which conveys the glass substrate 11 has the frame 41 which hold | stores a liquid. And the nozzle 23 which supplies the water as a coolant, and the cooling tank 40 filled with the cooling liquid 26 are provided, and the frame 41 holds the cooling liquid 26 on the surface of the glass substrate 11 and overflows into the cooling tank 40 As such, it has a predetermined height h. Although the details of the substrate mounting table 31 are omitted, the substrate mounting table 31 is connected to a conveying unit (not shown), and the glass substrate 11 is placed and conveyed at a predetermined conveying speed.

  Also in the fifth embodiment, as in the first to fourth embodiments, the laser processing apparatus 1 equipped with the laser processing unit 30 for performing laser processing and the processing control device 34 for controlling the processing position and processing timing is provided. Use.

  The cooling liquid 40 is filled in the cooling tank 40, and the frame 41 for storing the liquid is installed on the glass substrate 11 installed on the substrate mounting table 31. The cooling liquid 26 is supplied to the surface of the glass substrate 11 from the nozzle 23. Do. By supplying the cooling liquid 26 while overflowing, laser irradiation is performed while holding water corresponding to the height h of the frame 41 on the surface of the glass substrate 11.

  Here, it is desirable that the frame 41 has a height at which water as the coolant 26 forms a water film with a thickness of 20 nm or more and 1 mm or less on the surface of the glass substrate 11. If it is less than 20 nm, the cooling effect is not sufficient, and if it exceeds 1 mm, the processing accuracy of the through hole is reduced due to the refraction of the laser beam.

  As described above, since the cooling liquid can be supplied while controlling the thickness of the cooling liquid on the glass substrate 11, a fine through-hole with high accuracy without causing positional deviation due to laser light refraction. Can be formed at high density. In addition, since a uniform thin water film is formed, a cooling effect can be obtained, and residues formed by laser irradiation can flow out together with the water film from the formed through holes 12. Further, since the back side of the substrate mounting table 31 on which the glass substrate 11 is mounted is also covered with water, the cooling effect from the back surface is also high, the processing accuracy is enhanced, and the generation of stress distortion and thus cracks is suppressed It is possible to obtain a high-temperature glass interposer. Therefore, according to the laser processing method of the fifth embodiment, high-quality laser processing without stress distortion and crackless can be realized on the glass substrate 11 while maintaining positional accuracy, and high reliability can be achieved. It is possible to obtain a glass interposer provided with a highly conductive wiring circuit.

In the first to fifth embodiments, the formation of the through holes 12 in the glass substrate 11 has been described, but the workpiece is not limited to the glass substrate 11, and can be applied to silicon, compound semiconductors, organic substances, etc. is there. Further, the laser oscillator is not limited to the CO ₂ laser, and one having a wavelength that can be absorbed to the workpiece can be appropriately selected.

  The configuration shown in the above embodiment shows an example of the contents of the present invention, and can be combined with another known technique, and one of the configurations is possible within the scope of the present invention. Parts can be omitted or changed.

  DESCRIPTION OF SYMBOLS 1 laser processing apparatus, 10 glass interposer, 10A 1st main surface, 10B 2nd main surface, 11 glass substrate, 11A 1st main surface, 11B 2nd main surface, 12 through hole, 12S shallow groove, 13 1st electrode, 14 second electrode 15 through electrode 16 CPU 17 memory 18 solder ball 19 printed circuit board 19P wiring pattern 21 hydrophilic film 22 coolant agent 23 nozzle 24 gel coolant agent 25 coolant agent 30 Laser processing unit, 31 substrate mounting table, 32 laser oscillators, 33X, 33Y galvano scanner, 34 processing control device, 35X, 35Y galvano mirror, 36 Fθ lens, 37 laser light, 40 cooling tank, 100 memory device.

Claims (6)

Applying a hydrophilic treatment to a workpiece, which is a glass substrate, and covering the surface of the workpiece with a cooling film;
While conveying the workpiece coated with the cooling film at a constant speed, laser light is scanned by a galvano scanner under cooperative control, and the laser beam is irradiated to the workpiece through the cooling film, and the laser Forming a through hole in the area to be irradiated with light;
A laser processing method comprising: Forming a water film having a thickness of 20 nm or more and 1 μm or less on a workpiece which is a glass substrate, and covering the surface of the workpiece with a cooling film;
While conveying the workpiece coated with the cooling film at a constant speed, laser light is scanned by a galvano scanner under cooperative control, and the laser beam is irradiated to the workpiece through the cooling film, and the laser Forming a through hole in the area to be irradiated with light;
A laser processing method comprising: Supplying a coolant from the nozzle to the surface of the workpiece, which is a glass substrate, and covering the surface of the workpiece with a cooling film;
While conveying the workpiece coated with the cooling film at a constant speed, laser light is scanned by a galvano scanner under cooperative control, and the laser beam is irradiated to the workpiece through the cooling film, and the laser Forming a through hole in the area to be irradiated with light;
A laser processing method comprising: Selectively supplying a coolant to the surface of the workpiece, which is a glass substrate, and selectively forming a cooling film on the surface of the workpiece;
The laser beam is scanned by a galvano-scanner under cooperative control while conveying the workpiece on which the cooling film is selectively formed at a constant speed, and the workpiece is scanned via the selectively formed cooling film. Irradiating the laser beam on the surface and forming a through hole in a region irradiated with the laser beam;
A laser processing method comprising: Prior to the step of selectively forming the cooling film,
Forming a shallow groove in the through hole forming region of the workpiece by laser irradiation;
Filling the shallow groove with the coolant;
In the step of forming the through hole,
The laser processing method according to claim 4, wherein the through holes are formed by laser irradiation in accordance with the shallow groove while aligning with the coolant. A coolant supply unit for supplying a coolant to a surface of a workpiece and forming a cooling film on the surface;
A transport unit that transports the workpiece coated with the cooling film at a constant speed by the supply of the coolant;
A laser oscillator,
A scanner for scanning laser light from the laser oscillator at a predetermined speed;
It is a laser processing apparatus which forms a through-hole by performing laser irradiation to the said to-be-processed object via the said cooling film, Comprising:
The conveyance part which conveys the said to-be-processed object is equipped with the frame which surrounds the said to-be-processed object,
The coolant supply unit includes a cooling tank filled with the coolant, and a feed nozzle for feeding the coolant to the workpiece.
The laser processing apparatus , wherein the frame has a predetermined height, holds the coolant on the surface of the workpiece, and overflows the coolant into the cooling tank .

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