JP2015123461A - Laser processing method and manufacturing method for substrate where through hole is formed - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laser processing method which enables substrate damage due to laser irradiation heat to be suppressed, and a dummy plate to be removed easily from a substrate where through holes are formed by laser irradiation and a manufacturing method for the substrate where a through hole is formed.SOLUTION: A laser processing method which enables through holes (4) to be opened in a dummy plate (3) by laser irradiation from the surface of the dummy plate with the dummy plate (3) laminated on a substrate (1) via an intervening substance, a dummy plate lamination step for laminating a dummy plate on a substrate so that a layer of a liquid intervening substance (2) as the intervening substance may be formed between the substrate and the dummy plate has a hole opening step for forming making through holes in the substrate and making the liquid intervening substance generate bubbles (5) by laser irradiation from the surface of the dummy plate, and a dummy plate removal step for removing the dummy plate after the hole opening step from the substrate where through holes are formed.

Description

  The present invention relates to a laser processing method in which a dummy plate is stacked on a substrate via an intervening substance, and a through hole is formed in the substrate by irradiating a laser beam from the surface of the dummy plate, and a method for manufacturing the substrate in which the through hole is formed. .

  As a conventional laser processing method for making a through hole in a substrate by laser irradiation, in order to suppress chipping of the substrate or adhesion of a molten material to the substrate, a process of laminating a dummy plate on the substrate via an intervening substance, a dummy Some have a process of processing a hole by irradiating a laser from above the plate and a process of removing the dummy plate (see, for example, Patent Document 1).

Japanese Patent Application No. 2008-523584

However, the prior art has the following problems.
In the conventional laser processing method, there is a problem that it is difficult to remove the dummy plate from the substrate after the drilling process by laser irradiation is completed. Therefore, for example, in Patent Document 1, in order to facilitate the removal of the dummy plate, an adhesive whose adhesive strength is reduced by laser irradiation is used as an intervening substance, and the dummy plate is laminated on the substrate or before the dummy plate removal process. Intervening substances are dissolved.

  However, in the laser processing method of Patent Document 1, the process is complicated and the adhesive in the dummy plate, the substrate, and the adhesive changes in quality due to the influence of the temperature increase caused by laser irradiation in the drilling process. There was a problem that the adhesive strength was not sufficiently reduced even after laser irradiation for reducing the force. Further, the pressure-sensitive adhesive cannot be completely dissolved, and the substrate is damaged in the process of removing the dummy plate.

  As described above, in the laser processing method in which the dummy plate and the substrate are stacked via the intervening material, then the hole is processed by laser irradiation, and then the dummy plate is removed, the dummy plate There are problems that it is difficult to remove the intervening substance from the object to be processed, and that the removal process becomes complicated and the substrate is damaged.

  In particular, when the substrate is made of a brittle material such as glass or silicon, breakage of the substrate in the process of removing the dummy plate becomes a problem.

  The present invention has been made to solve the above-described problems, and is a laser processing in which a dummy plate is laminated on a substrate via an intervening substance, and a laser is irradiated from the surface of the dummy plate to open a through hole in the substrate. In the method, the laser processing method and the manufacturing method of the substrate in which the through hole is formed can suppress the breakage of the substrate due to the laser irradiation heat and can easily remove the dummy plate from the substrate in which the through hole is formed by the laser irradiation. The purpose is to obtain.

  In the laser processing method according to the present invention, a dummy plate is laminated on a substrate via an intervening substance, and a laser is irradiated from the surface of the dummy plate to open a through hole in the substrate. A dummy plate is laminated on the substrate so that a layer of liquid inclusion material is formed, and the substrate after the dummy plate lamination process is irradiated with laser from the surface of the dummy plate, thereby forming a through hole in the substrate. It has a drilling process for forming bubbles in the liquid inclusion material and a dummy plate removing process for removing the dummy plate after the drilling process from the substrate in which the through holes are formed.

  Further, the method of manufacturing a substrate having a through hole according to the present invention includes a dummy plate stacking process in which a dummy plate is stacked on a substrate so that a layer of liquid inclusion material as an inclusion material is formed between the substrate and the dummy plate. The substrate after the dummy plate stacking process is irradiated with laser from the surface of the dummy plate to form a through hole in the substrate and generate bubbles in the liquid inclusion material, and a dummy after the drilling process. And a dummy plate removing process for removing the plate from the substrate in which the through hole is formed.

  According to the present invention, in a laser processing method in which a dummy plate is stacked on a substrate via an intervening substance, and a through hole is formed in the substrate by irradiating a laser beam from the surface of the dummy plate, A layer of material is formed so that bubbles are generated in the liquid intervening material during laser irradiation to reduce the bonding force between the substrate and the dummy plate. As a result, the laser processing method and the manufacturing method of the substrate in which the through hole is formed can suppress the breakage of the substrate by the laser irradiation heat and can easily remove the dummy plate from the substrate in which the through hole is formed by the laser irradiation. Can be obtained.

It is a flowchart of the laser processing method in Embodiment 1 of this invention. It is a conceptual diagram which shows the dummy plate lamination | stacking process in Embodiment 1 of this invention. It is a conceptual diagram which shows the drilling process in Embodiment 1 of this invention. It is a schematic block diagram of the laser processing apparatus in Embodiment 1 of this invention. It is an image figure of the drilling process by the laser irradiation in Embodiment 1 of this invention. It is a conceptual diagram which shows the bubble expansion standby process in Embodiment 1 of this invention.

  Hereinafter, preferred embodiments of a laser processing method and a method of manufacturing a substrate having a through hole according to the present invention will be described with reference to the drawings. In addition, the same code | symbol is attached | subjected and demonstrated about the part which is the same or it corresponds in each figure.

Embodiment 1 FIG.
FIG. 1 is a flowchart of a laser processing method according to Embodiment 1 of the present invention. In FIG. 1, a drilling process (S2) by laser irradiation is performed after the stacking process (S1) of the dummy plate 3 for stacking the dummy plate 3 with the liquid inclusion material 2 interposed in the substrate 1. Then, a bubble expansion standby process (S3) is performed, and finally, a dummy plate removing process (S4) for removing the dummy plate 3 from the substrate 1 is performed. Here, in the drilling process (S2) by laser irradiation, the bubbles 5 are generated in the liquid inclusion material 2 at the same time as the through holes 4 (see FIG. 3) are formed in the dummy plate 3 and the substrate 1.

  The first embodiment exhibits a great effect when the material of the substrate 1 is a brittle material such as glass or silicon. That is, this is a case of so-called thermal processing or thermal ablation processing in which the drilling process by laser irradiation is based on the temperature rise generated in the irradiation target by laser irradiation.

In the first embodiment, the case where the material of the substrate 1 is glass and the laser light source is a CO ₂ laser (wavelength: 9.3 μm or 10.6 μm) is described, but the material of the substrate 1 is not necessarily limited to glass. Is not to be done. For example, a semiconductor such as silicon may be used.

Drilling by laser irradiation is classified into thermal processing and processing that directly cuts molecular bonds. The latter is possible only with an ultraviolet laser with a high photon energy (short wavelength) or an ultrashort pulse laser with a short pulse width and a high laser electric field. On the other hand, laser processing using a laser having a wavelength of visible region and infrared region and a laser pulse width of approximately 10 ⁻⁹ seconds or more is thermal processing. Further, drilling using a CO ₂ laser having a wavelength of 9.3 μm or 10.6 μm and a pulse width of 100 nanoseconds or more is also thermal processing.

In laser drilling of the substrate 1, it is required to achieve both productivity and processing quality. The standard of productivity that can be expected for mass production is from several hundred holes / second to 1,000 holes / second. The pulse CO ₂ laser can generate a high average output, and high productivity can be expected by applying the CO ₂ laser.

On the other hand, since the processing by the CO ₂ laser is the thermal processing as described above, if a hole is formed in the substrate 1 using the CO ₂ laser, a thermal effect is generated around the hole formed in the substrate 1. There is a problem of doing. Specifically, the heat influence here is adhesion of a melt around the hole, deformation around the hole, or generation of cracks. Although it is possible to reduce the thermal effect by shortening the laser pulse width, it is difficult to completely suppress the thermal effect as long as it is thermal processing.

Further, when a pulsed CO ₂ laser is used as the laser oscillator 6, it is difficult to focus on a beam having a wavelength as long as about 10 μm and smaller than φ50 μm although the output is high and a high processing speed can be expected.

  Therefore, in the first embodiment, as shown in FIG. 1, in the dummy plate stacking process, the dummy plate 3 is stacked and then the punching process is performed. As a result, the following two effects are obtained.

First, a processed hole having a diameter smaller than the laser focusing diameter can be obtained. This is because laser-processed holes are generally tapered with a large hole diameter on the irradiation side and a small hole diameter on the opposite side. By drilling after laminating the dummy plates 3, a processed hole smaller than the condensing diameter can be obtained in the substrate 1 sandwiched between the dummy plates 3, and even with a CO ₂ laser, φ40 μm The following processed holes are obtained.

  Secondly, the thermal effect on the surface of the substrate 1 can be reduced. This is because the thermal effects such as adhesion of the melt around the hole, deformation around the hole, and generation of cracks are most noticeable at the laser incident portion, that is, the outermost surface of the dummy plate 3.

  Furthermore, the first embodiment has a technical feature in that the liquid inclusion material 2 is used as the inclusion material between the dummy plate 3 and the substrate 1. Then, as shown in FIG. 1, in the bubble expansion standby process, after the bubbles 5 generated in the liquid inclusion material 2 are grown during the processing operation, the dummy plate 3 is removed, so that the substrate 1 of the dummy plate 3 is removed. Can be easily removed. As a result, the dummy plate removal process can be simplified and the yield can be increased.

In particular, when a pulsed CO ₂ laser is used, the thermal effect is large, and the intervening material undergoes thermal denaturation, making it difficult to remove the dummy plate 3 from the substrate 1. Furthermore, even when the substrate 1 is made of a brittle material such as glass, the substrate 1 is easily damaged in the process of removing the dummy plate 3, so that the effect is great.

Hereinafter, each process of FIG. 1 is demonstrated in detail based on drawing after FIG.
FIG. 2 is a conceptual diagram showing a dummy plate stacking process in the first embodiment of the present invention. FIG. 2A shows a cross-sectional view, and FIG. 2B shows a top view.

  In FIG. 2, a dummy plate 3 is laminated on the front and back surfaces of the substrate 1 with a liquid intervening material 2 interposed. Here, the front surface is a surface on the laser irradiation side in the drilling process by laser irradiation after this process, and the back surface is a surface opposite to the front surface. When the processing quality of the back surface is not questioned, the dummy plate 3 may be laminated only on the front side of the substrate 1. The substrate 1 is a glass plate having a thickness of 50 μm to 500 μm, specifically, quartz, borosilicate glass, non-alkali glass, or the like. As the liquid inclusion substance 2, water or an aqueous surfactant solution can be used.

As the material of the dummy plate 3, glass or metal can be used. The dummy plate 3 is required to have a high absorption coefficient at the wavelength of the CO ₂ laser, but on the other hand, a substance having a high melting point and a high processing threshold is desirable. When a processing threshold is low, for example, a resin such as PET: polyethylene terephthalate is used as the dummy plate 3, a large hole is opened in the drilling process, and a processing hole formed on the substrate 1 by stacking the dummy plates 3 is formed. The effect of improving the processing quality is reduced.

  In addition, with respect to the thickness of the dummy plate 3, if the thickness is increased, the effect of suppressing the thermal influence on the substrate 1 can be made relatively large. On the other hand, the through hole 4 is formed in the subsequent drilling process. The number of laser pulses to form increases, and the processing speed decreases. Therefore, if the thickness of the dummy plate 3 is 0.5 to 2.0 times that of the substrate 1, the balance between the thermal effect suppressing effect and the processing speed is good.

  FIG. 3 is a conceptual diagram showing a drilling process in the first embodiment of the present invention. FIG. 3A shows a cross-sectional view, and FIG. 3B shows a top view. FIG. 4 is a schematic configuration diagram of the laser processing apparatus according to Embodiment 1 of the present invention. Hereinafter, the drilling process by laser irradiation will be described with reference to FIGS.

In FIG. 3, the pulse CO ₂ laser is irradiated from the surface side of the substrate 1. As a result, the through holes 4 are formed in the order of the front-side dummy plate 3, the substrate 1, and the back-side dummy plate 3. At this time, bubbles 5 are generated in the through holes 4 formed in the liquid inclusion material 2.

  Here, as shown in FIG. 4, the laser processing apparatus for irradiating the laser includes a laser oscillator 6, a processing optical system 7, a mask 8, a galvano scanner 9, and a processing lens 10.

As the laser oscillator 6, in addition to the pulsed CO ₂ laser oscillator shown in the first embodiment, the same effect can be obtained even when using another pulsed laser having absorption on a glass plate, such as an excimer laser or a solid-state laser. . The repetition frequency of the laser oscillator 6 is several kHz to several hundred kHz.

  The laser beam generated by the laser oscillator 6 is adjusted in beam diameter and divergence angle by the processing optical system 7. The adjusted laser beam is applied to the mask 8. A substantially circular opening is formed in the mask 8, and a part of the laser beam passes through the opening and is shaped into a circle. The laser beam that has passed through the mask 8 is reflected by the galvano scanner 9 and focused on the processing object 11 by the processing lens 10.

  At this time, a stable processed hole shape can be obtained by arranging the mask 8 to be reduced and transferred onto the processing object 11 by the processing lens 10. For example, when the aperture diameter of the mask 8 is φ1.0 mm and the reduction transfer magnification is 1/20, the beam diameter on the workpiece 11 is 1.0 × 1/20 = 0.05 mm, that is, φ50 μm. It becomes. Here, the processing object 11 is the substrate 1 after the dummy plate stacking process in the first embodiment.

  By rotating the galvano scanner 9 at high speed, the position of the laser beam on the workpiece 11 can be positioned at high speed. The positioning speed of the laser beam by the galvano scanner 9 reaches several thousand holes / second.

  The processing object 11 is installed on the processing table 12. The processing table 12 can be moved in a wide range (for example, 600 mm × 500 mm as a substrate size) by a biaxial moving mechanism using a stepping motor, a linear motor or the like, and a galvano scanner 9 and a processing lens 10 called a scan area. It is possible to perform laser processing in a wider area than the laser beam positioning possible range (normally within about 200 mm).

  That is, when the entire surface of the processing object 11 of 600 mm × 500 mm is processed using the galvano scanner 9 and the processing lens 10 in the 100 mm scan area, the processing in the 100 mm scan area is performed by rotating the galvano scanner 9. Processing by high-speed beam positioning. Next, the processing table 12 is moved 100 mm. Then, after moving 100 mm, a region of 100 mm is processed by high-speed beam positioning as before. Subsequently, the processing table 12 is moved 100 mm. By repeating the above, the entire surface of the processing object 11 can be processed. Although different depending on the object 11, laser processing by high-speed beam positioning can realize a processing speed of several hundred holes / second to several thousand holes / second.

FIG. 5 is an image diagram of drilling by laser irradiation in the first embodiment of the present invention. Through holes 4 are formed in the dummy plate 3 and the substrate 1 by laser irradiation. In a processing machine using a long CO ₂ laser with a wavelength of 10 μm, when the laser diameter transferred onto the processing object 11 is about φ50 μm to 100 μm, the minimum beam diameter is the place where the transferred image is obtained It is.

  The laser beam a does not become smaller than that in the air, but the processing progresses while reflecting the side surface of the processing hole 13 as indicated by an arrow in FIG. As a result, the processed hole 13 becomes thinner as it digs and becomes a tapered shape. The phenomenon that the processed hole 13 becomes tapered also occurs in the dummy plate 3 and the substrate 1 in the first embodiment. Therefore, the processed hole 13 formed in the substrate 1 has a smaller diameter than the processed hole 13 formed in the front-side dummy plate 3.

  Therefore, in the process of forming the processed hole 13 in the first embodiment, adjustment is performed so that a transfer image of the mask 8 is obtained on the surface side of the dummy plate 3. As described above, the laser beam diameter is minimized at the place where the transfer image is obtained. As a result, by forming the transfer image of the mask 8 on the outermost surface of the dummy plate 3, a minimum hole is formed in the substrate 1. It is possible to form.

  Formation of the through hole 4 requires irradiation with a laser beam as a plurality of pulses. At the moment when the through hole 4 is formed, the air outside the dummy plate 3 is introduced into the liquid inclusion material 2 through the through hole 4, and bubbles 5 are generated in the liquid inclusion material 2. When the through holes 4 are formed, the through holes 4 are formed in order from the front surface, and thus the through holes 4 are formed in the order of the front surface side dummy plate 3 → the substrate 1 → the back surface side dummy plate 3.

  Therefore, if the time interval of the laser pulse irradiated to a certain through-hole 4 is too large, the bubbles 5 generated in the liquid inclusion material 2 between the front-side dummy plate 3 and the substrate 1 become too large and penetrate the substrate 1. The effect of suppressing the thermal influence when forming the holes 4 and the effect of obtaining the small processed holes 13 are reduced. In the inventor's experiment, when the time interval between the laser pulses is 1 msec or less, there is no problem that the effect is reduced.

  FIG. 6 is a conceptual diagram showing a bubble expansion standby process in the first embodiment of the present invention. FIG. 6A shows a cross-sectional view, and FIG. 6B shows a top view. Bubbles 5 generated in the liquid inclusion material 2 during the drilling process expand as time passes. Expansion of the bubbles 5 depends on the pitch of the through holes 4, but the bubbles 5 generated in the adjacent through holes 4 are connected in several seconds to several tens of seconds. When the bubbles 5 are connected to each other, the connection and expansion of the bubbles 5 rapidly progress, and when the connection of the bubbles 5 is almost completed, the expansion of the bubbles 5 almost stops.

  In the state where the expansion of the bubbles 5 has progressed, for example, by moving the dummy plate 3 and the substrate 1 while holding the suction plate using the suction pad, the bubbles 5 are sufficient. It can be removed smoothly.

  As described above, according to the first embodiment, in a laser processing method in which a dummy plate is stacked on a substrate via an intervening substance and a through hole is formed in the substrate by laser irradiation from the surface of the dummy plate, A layer of a liquid intervening material as an intervening material is formed on the substrate so that bubbles are generated in the liquid intervening material during laser irradiation, thereby reducing the bonding force between the substrate and the dummy plate.

  As a result, even when the substrate is a brittle material or when the temperature rise due to laser irradiation during the drilling process is significant, damage to the substrate due to laser irradiation heat is suppressed, and through holes are formed by laser irradiation. The dummy plate can be easily removed from the substrate.

Embodiment 2. FIG.
In the second embodiment, after the through hole 4 is formed in the substrate 1 in the drilling process in the first embodiment, the laser irradiation is continued for a certain period of time, thereby causing bubbles in the liquid inclusion material 2. A method of further growing 5 and making it easier to remove the dummy plate 3 after laser irradiation will be described.

  Since the second embodiment is different from the first embodiment only in the drilling process, only the drilling process will be described.

  In the first embodiment, the bubbles 5 are generated by the laser irradiation during the formation of the through holes 4 in the drilling process. However, in this case, the bubbles 5 may be generated sufficiently, but the bubbles 5 are not sufficiently generated depending on the processing conditions, the processing object 11 and the diameter of the processing hole 13, and the bubble expansion standby process after that is sufficient. The bubbles 5 may not expand.

  Therefore, in the second embodiment, in order to ensure the generation of the bubbles 5, the laser pulse is continuously irradiated even after the through hole 4 is formed. For example, when the processing hole 13 by laser irradiation penetrates when three pulses of the laser beam are irradiated, the generation of the bubbles 5 is made remarkable by irradiating the same through hole 4 with the fourth pulse and the fifth laser pulse. I can do it.

  As described above, according to the second embodiment, it is possible to reliably generate bubbles and more easily remove the dummy plate after laser irradiation.

Embodiment 3 FIG.
In the third embodiment, in the bubble expansion standby process in the first embodiment, by applying an ultrasonic wave to the liquid inclusion material 2 via the dummy plate 3, the bubbles 5 in the liquid inclusion material 2 are grown. A method of shortening the time for the bubble expansion standby process will be described in advance.

  Since the third embodiment is different from the first embodiment only in the bubble expansion standby process, only the bubble expansion standby process will be described.

  In the first embodiment, a standby time is provided in order to expand the bubbles 5 in the bubble expansion standby process. However, depending on the processing conditions, the processing object 11, and the diameter of the processing hole 13, the bubbles 5 may not expand sufficiently in the bubble expansion standby process.

  Therefore, in the third embodiment, in order to ensure the expansion of the bubbles 5, the ultrasonic wave is applied to the liquid inclusion material 2 by applying an ultrasonic vibrator from the substrate 1 of the dummy plate 3 after the processing. . In this way, by minutely vibrating the liquid inclusion material 2, the liquid inclusion material 2 is discharged to the outside of the dummy plate 3 through the through holes 4, and the bubbles 5 are likely to grow.

  As described above, according to the third embodiment, the expansion of the bubble area can be promoted, and the productivity can be improved.

  1 substrate, 2 liquid inclusion material, 3 dummy plate, 4 through hole, 5 bubble, 6 laser oscillator, 7 processing optical system, 8 mask, 9 galvano scanner, 10 processing lens, 11 processing target, 12 processing table, 13 processing hole A Laser beam.

Claims (6)

In a laser processing method of laminating a dummy plate via an intervening substance on a substrate, and irradiating a laser from the surface of the dummy plate to open a through hole in the substrate,
A dummy plate laminating process for laminating the dummy plate on the substrate such that a layer of liquid intervening material as the intervening material is formed between the substrate and the dummy plate;
The substrate after the dummy plate lamination process is subjected to a laser drilling process from the surface of the dummy plate to form a through hole in the substrate and generate bubbles in the liquid inclusion material,
And a dummy plate removing step of removing the dummy plate after the drilling step from the substrate on which the through hole is formed. The laser processing method according to claim 1,
A laser processing method further comprising: a bubble expansion standby process for waiting for expansion of the bubbles of the liquid inclusion material generated by the punching process between the punching process and the dummy plate removing process. The laser processing method according to claim 2,
A laser processing method of applying ultrasonic waves to the liquid inclusion material through the dummy plate in the bubble expansion standby process. In the laser processing method of any one of Claim 1 to 3,
In the drilling process, the laser irradiation is continued for a certain period after an irradiation time required to open the through hole in the substrate has elapsed. In the laser processing method of any one of Claim 1 to 4,
The substrate is a glass substrate or a silicon substrate. A method of manufacturing a substrate in which a through hole is formed,
A dummy plate laminating process of laminating the dummy plate on the substrate so that a layer of liquid intervening material as an intervening material is formed between the substrate and the dummy plate;
The substrate after the dummy plate lamination process is subjected to a laser drilling process from the surface of the dummy plate to form a through hole in the substrate and generate bubbles in the liquid inclusion material,
A method of manufacturing a substrate with a through hole, comprising: removing a dummy plate after the drilling process from the substrate with the through hole formed therein.

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