JP2014019610A - Laser processing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laser processing method which can suppress deterioration of deflective strength of an effective part cut from a tabular processing object including a glass plate and protect an outer surface of the effective part in processing.SOLUTION: The laser processing method includes: a first process for forming a resist on a front surface 1a and a back surface 1b of a processing object 1; a second process for cutting out an effective part 17 from the processing object 1 after the first process by moving a condensing point of a laser beam relatively along predetermined cutting lines 51 and 52 which extends along a side surface 19 of the effective part 17 to form a modification region inside a strengthened glass 10 along the lines 51 and 52 and extending a crack generated in the modification region to a thickness direction of the processing object 1; and a third process for eliminating the modification region existing on the side surface 19 of the effective part 17 and removing the resist existing on a front surface 17a and a back surface 17b of the effective part 17 after the second process.

Description

  The present invention relates to a laser processing method for cutting out an effective portion from a plate-like processing object including a glass plate.

  As a laser processing method in the above technical field, a plate-shaped workpiece is irradiated with a laser beam, thereby forming a modified region inside the workpiece along the planned cutting line, and generated from the modified region. It is known that a workpiece is cut along a planned cutting line by extending a crack in the thickness direction of the workpiece (for example, see Patent Document 1).

JP 2004-343008 A

  However, by carrying out the laser processing method as described above, and cutting out the effective portion from the plate-like processing object provided with the glass plate, due to the modified region existing on the side of the cut out effective portion, There is a possibility that the bending strength of the cut-out effective part is lowered. In addition, if the effective portion is used for a touch panel of a portable terminal, for example, a resin film or the like may be formed on the outer surface of the effective portion, so it is necessary to protect the outer surface of the effective portion during processing. is there.

  Therefore, the present invention can prevent the bending strength from being lowered in the effective portion cut out from the plate-like workpiece including the glass plate, and can protect the outer surface of the effective portion during processing. An object of the present invention is to provide a laser processing method that can be used.

  The laser processing method of the present invention is a laser processing method for cutting out an effective portion from a plate-like processing object including a glass plate, and includes a first step of forming a protective film on the front surface and the back surface of the processing object, After the first step, the laser light condensing point is relatively moved along the planned cutting line extending along the side surface of the effective portion, thereby moving the glass plate along the planned cutting line. Forming a modified region and extending a crack generated in the modified region in the thickness direction of the workpiece, thereby cutting the effective portion from the workpiece; and after the second step, And a third step of removing the modified region existing on the side surface and removing the protective film present on the front surface and the back surface of the effective portion.

  In this laser processing method, after forming a protective film on the front and back surfaces of the workpiece, a process for cutting out the effective portion from the workpiece is performed, and then a modified region existing on the side surface of the effective portion. And the protective film present on the front and back surfaces of the effective portion is removed. Therefore, at the time of processing, the front and back surfaces of the effective portion are protected by the protective film, and the modified region that contributes to reducing the bending strength is removed from the cut out effective portion. Therefore, according to this laser processing method, it is possible to prevent the bending strength from being lowered in the effective portion cut out from the plate-like processing object including the glass plate, and to reduce the outer surface of the effective portion during processing. Can be protected.

  Here, in the first step, a protective film is formed so as to cover the entire area of the front and back surfaces of the workpiece, and in the second step, the protective film is formed on the front or back surface of the workpiece. The laser beam may be incident on the object to be processed. According to this, since the protective film that can transmit the laser light is used, patterning of the protective film becomes unnecessary, so that the number of processing steps can be reduced.

  Alternatively, in the first step, a protective film is formed on at least one of the front and back surfaces of the workpiece so as to cover a region other than the region along the planned cutting line, and in the second step, along the planned cutting line. The laser beam may be incident on the object to be processed through the region. According to this, the degree of freedom of selection of the protective film can be increased, such as the use of a protective film with low laser beam transparency.

  The glass plate may be a tempered glass plate. At this time, in the third step, the modified region may be removed by mechanical polishing and then the protective film may be removed, or the modified region may be removed by chemical treatment and then the protective film is removed. May be. Alternatively, in the third step, the modified region may be removed by chemical treatment and the protective film may be removed. In this case, it is possible to further reduce the processing man-hours.

  Further, the glass plate is an unstrengthened glass plate, and the glass plate may be strengthened in the third step. At this time, in the third step, the modified region may be removed by mechanical polishing, and then the protective film may be removed and the glass plate may be strengthened, or the modified region may be removed by chemical treatment, and then In addition, the protective film may be removed to strengthen the glass plate. Alternatively, in the third step, the modified region may be removed by chemical treatment and the protective film may be removed, or the protective film may be removed by chemical treatment and the glass plate may be strengthened. In this case, it is possible to further reduce the processing man-hours.

  ADVANTAGE OF THE INVENTION According to this invention, while being able to suppress that a bending strength falls in the effective part cut out from the plate-shaped process target provided with a glass plate, it can protect the outer surface of an effective part at the time of a process. It is possible to provide a laser processing method that can be used.

It is a schematic block diagram of the laser processing apparatus used for formation of a modification area | region. It is a top view of the processing target object used as the object of formation of a modification field. It is sectional drawing along the III-III line of the workpiece of FIG. It is a top view of the processing target after laser processing. It is sectional drawing along the VV line of the workpiece of FIG. It is sectional drawing along the VI-VI line of the processing target object of FIG. It is the (a) top view and (b) sectional view of the processing target used as the object of the laser processing method of a 1st embodiment of the present invention. It is the (a) top view and (b) sectional view of the processing object in which the laser processing method of a 1st embodiment of the present invention is carried out. It is the (a) top view and (b) sectional view of the processing object in which the laser processing method of a 1st embodiment of the present invention is carried out. It is the (a) top view and (b) sectional view of the effective part in which the laser processing method of a 1st embodiment of the present invention is carried out. It is the (a) top view and (b) sectional view of the effective part in which the laser processing method of a 1st embodiment of the present invention is carried out. It is the (a) top view and (b) sectional view of the effective part used as the object of the laser processing method of a 1st embodiment of the present invention. It is the (a) top view and (b) sectional view of the processing target used as the object of the laser processing method of a 2nd embodiment of the present invention. It is the (a) top view and (b) sectional view of the processed object in which the laser processing method of a 2nd embodiment of the present invention is carried out. It is the (a) top view and (b) sectional view of the processed object in which the laser processing method of a 2nd embodiment of the present invention is carried out. It is the (a) top view and (b) sectional view of the effective part in which the laser processing method of 2nd Embodiment of this invention is implemented. It is the (a) top view and (b) sectional view of the effective part in which the laser processing method of 2nd Embodiment of this invention is implemented. It is the (a) top view and (b) sectional view of the effective part in which the laser processing method of 2nd Embodiment of this invention is implemented.

  DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In addition, in each figure, the same code | symbol is attached | subjected to the same or an equivalent part, and the overlapping description is abbreviate | omitted.

  In the laser processing method of one embodiment of the present invention, the modified region that is the starting point of cutting inside the workpiece along the planned cutting line by irradiating the processing target with laser light along the planned cutting line Form. Therefore, the formation of the modified region will be described with reference to FIGS. 1 to 6 without limiting the material of the workpiece.

  As shown in FIG. 1, a laser processing apparatus 100 includes a laser light source 101 that oscillates a laser beam L, a dichroic mirror 103 that is arranged so as to change the direction of the optical axis (optical path) of the laser beam L, and A condensing lens 105 for condensing the laser light L. Further, the laser processing apparatus 100 includes a support base 107 for supporting the workpiece 1 irradiated with the laser light L condensed by the condensing lens 105, and a stage 111 for moving the support base 107. And a laser light source control unit 102 for controlling the laser light source 101 in order to adjust the output, pulse width, etc. of the laser light L, and a stage control unit 115 for controlling the drive of the stage 111.

  In this laser processing apparatus 100, the laser light L emitted from the laser light source 101 has its optical axis changed by 90 ° by the dichroic mirror 103, and the inside of the processing object 1 placed on the support base 107. The light is condensed by the condensing lens 105. At the same time, the stage 111 is moved, and the workpiece 1 is moved relative to the laser beam L along the planned cutting line 5. As a result, a modified region along the planned cutting line 5 is formed on the workpiece 1.

  As the workpiece 1, plate-like members (for example, substrates, wafers, etc.) made of various materials (for example, glass, semiconductor material, piezoelectric material, etc.) are used. As shown in FIG. 2, a scheduled cutting line 5 for cutting the workpiece 1 is set in the workpiece 1. The planned cutting line 5 is a virtual line extending linearly. When forming a modified region inside the workpiece 1, as shown in FIG. 3, the laser beam L is projected along the planned cutting line 5 in a state where the focused point P is aligned with the inside of the workpiece 1. It moves relatively (that is, in the direction of arrow A in FIG. 2). Thereby, as shown in FIGS. 4 to 6, the modified region 7 is formed inside the workpiece 1 along the planned cutting line 5, and the modified region 7 formed along the planned cutting line 5 is formed. It becomes the cutting start area 8.

  In addition, the condensing point P is a location where the laser light L is condensed. Further, the planned cutting line 5 is not limited to a straight line, but may be a curved line, or may be a line actually drawn on the surface 3 of the workpiece 1 without being limited to a virtual line. In addition, the modified region 7 may be formed continuously or intermittently. Further, the modified region 7 may be in the form of a line or a dot. In short, the modified region 7 only needs to be formed at least inside the workpiece 1. In addition, a crack may be formed starting from the modified region 7, and the crack and modified region 7 may be exposed on the outer surface (front surface, back surface, or outer peripheral surface) of the workpiece 1.

  Incidentally, the laser light L here passes through the workpiece 1 and is particularly absorbed near the condensing point inside the workpiece 1, thereby forming the modified region 7 in the workpiece 1. (Ie, internal absorption laser processing). Therefore, since the laser beam L is hardly absorbed by the surface 3 of the workpiece 1, the surface 3 of the workpiece 1 is not melted. In general, when a removed portion such as a hole or a groove is formed by being melted and removed from the front surface 3 (surface absorption laser processing), the processing region gradually proceeds from the front surface 3 side to the back surface side.

  By the way, the modified region formed in the present embodiment refers to a region where the density, refractive index, mechanical strength, and other physical characteristics are different from the surroundings. Examples of the modified region include a melt treatment region, a crack region, a dielectric breakdown region, a refractive index change region, and the like, and there is a region where these are mixed. Furthermore, as the modified region, there are a region in which the density of the modified region in the material to be processed is changed as compared with the density of the non-modified region, and a region in which lattice defects are formed (collectively these are high-density regions). Also known as the metastatic region).

In addition, the area where the density of the melt treatment area, the refractive index change area, the modified area has changed compared to the density of the non-modified area, and the area where lattice defects are formed are further included in these areas and the modified areas. In some cases, cracks (cracks, microcracks, etc.) are included in the interface between the non-modified region and the non-modified region. The included crack may be formed over the entire surface of the modified region, or may be formed in only a part or a plurality of parts. Examples of the processing object 1 include a substrate or wafer made of silicon, glass, LiTaO ₃ or sapphire (Al ₂ O ₃ ), or a material including such a substrate or wafer.

  Further, in the present embodiment, the modified region 7 is formed by forming a plurality of modified spots (processing marks) along the planned cutting line 5. The modified spot is a modified portion formed by one pulse shot of pulsed laser light (that is, one pulse of laser irradiation: laser shot). Examples of the modified spot include a crack spot, a melting treatment spot, a refractive index change spot, or a mixture of at least one of these.

Considering the required cutting accuracy, required flatness of the cut surface, thickness of the workpiece, type, crystal orientation, etc., the size of the modified spot and the length of the crack to be generated are appropriately determined. It is preferable to control.
[First Embodiment]

  As shown in FIG. 7, the workpiece 1 is a rectangular plate-shaped member having a front surface 1 a and a back surface 1 b and includes a tempered glass plate 10. The tempered glass plate 10 is a glass plate having a tensile stress layer and a compressive stress layer formed on both sides of the tensile stress layer. The tempered glass plate 10 is formed by immersing a normal glass (float glass) plate in a molten salt and forming a compressive stress layer on the surface layer of the glass plate by ion exchange (ion exchange method) or heating a normal glass plate. Thereafter, the glass plate is rapidly cooled (air cooling strengthening method) by blowing air on the surface of the glass plate. In the tempered glass plate 10, the thickness direction thereof coincides with the arrangement direction of the tensile stress layer and the compressive stress layer.

  A plurality (four in this case) of rectangular plate-shaped effective portions 17 are cut out from the workpiece 1 configured as described above as follows. The effective portion 17 has a front surface 17a, a back surface 17b, and four chamfered corners 18. Each corner 18 is rounded so that the chamfered surface 18a is a convex curved surface. It is. Such an effective portion 17 is used for a protective substrate of a display of a portable terminal.

  First, as shown in FIG. 8, a resist (protective film) 21 is formed on the front surface 1a and the back surface 1b so as to cover the entire area of the front surface 1a and the back surface 1b of the workpiece 1 (first step). When the effective portion 17 is used for a touch panel of a portable terminal, for example, a resin film or the like may be patterned on the outer surface of each effective portion 17 (that is, the front surface 1a and the back surface 1b of the workpiece 1). For this reason, the outer surface of the effective portion 17 is protected by the resist 21. The resist 21 is made of a material that transmits the laser light L, such as ZEONREX (registered trademark of Nippon Zeon), which is a resist for manufacturing a liquid crystal panel.

  After forming the resist 21, the workpiece 1 is placed on the support base 107 of the laser processing apparatus 100. At this time, a tape is attached to the back surface 1b side of the workpiece 1 or the workpiece 1 is vacuum-adsorbed on the workpiece 107 by forming the support 107 in a porous shape. Hold. Then, scheduled cutting lines 51 and 52 are set for the workpiece 1.

  The planned cutting line 51 is a straight line along the boundary surface between the adjacent effective portions 17 and 17 among the effective portions 17 arranged in a plurality of rows and a plurality of columns (here, 2 rows and 2 columns) with respect to the workpiece 1. It extends to the shape. That is, the planned cutting line 51 is along the end surface 17c that forms a boundary surface with the adjacent effective portion 17 among the side surfaces 19 of the effective portion 17 (that is, the four end surfaces 17c and the four chamfered surfaces 18a of each effective portion 17). So as to extend. Further, the planned cutting line 52 extends along the chamfered surface 18 a of the corner portion 18 in the side surface 19 of the effective portion 17.

  Subsequently, as shown in FIG. 9, the focusing point of the laser beam L is positioned inside the tempered glass plate 10 with the surface 1 a of the workpiece 1 as the laser beam incident surface, and processing is performed along each scheduled cutting line 51. The object 1 is irradiated with laser light L. That is, the condensing point of the laser beam L is relatively moved (scanned) along the planned cutting line 51. At this time, the laser beam L is incident on the processing target 1 through the resist 21 formed on the surface 1 a of the processing target 1. Thereby, the modified region 7A that generates the crack 80 extending in the thickness direction of the workpiece 1 is formed inside the tempered glass plate 10 along the scheduled cutting line 51 (second step).

  Further, the condensing point of the laser beam L is positioned inside the tempered glass plate 10 with the surface 1 a of the workpiece 1 as the laser beam incident surface, and the laser beam L is applied to the workpiece 1 along each scheduled cutting line 52. Irradiate. That is, the condensing point of the laser light L is relatively moved (scanned) along the planned cutting line 52. At this time, the laser beam L is incident on the processing target 1 through the resist 21 formed on the surface 1 a of the processing target 1. Thus, the modified region 7B that generates the crack 80 extending in the thickness direction of the workpiece 1 (see FIG. 10) is formed inside the tempered glass plate 10 along the planned cutting line 52 (second step). ).

  Then, by applying an external force along the planned cutting lines 51 and 52 and extending the crack 80 generated from the modified regions 7A and 7B in the thickness direction of the workpiece 1, the planned cutting lines 51 and 52 are formed. The workpiece 1 and the resist 21 are cut along the cut, and a plurality of effective portions 17 are cut out from the workpiece 1 (second step). As shown in FIG. 10, the modified regions 7A and 7B exist on the side surface 19 of the cut-out effective portion 17, and the resist 21 exists on the front surface 17a and the back surface 17b of the cut-out effective portion 17. doing.

  After cutting out the effective portion 17, the modified regions 7A and 7B existing on the side surface 19 of the effective portion 17 are removed as shown in FIG. 11, and the front surface 17a and the back surface 17b of the effective portion 17 are removed as shown in FIG. Is removed (third step) to obtain a plate-shaped effective portion 17 including the tempered glass plate 10.

  More specifically, the modified regions 7A and 7B are removed by mechanical polishing using a polishing tool or the like, and then the resist 21 is removed by chemical treatment such as etching using NaOH or KOH. Alternatively, the modified regions 7A and 7B are removed by chemical treatment such as etching using HF (hydrofluoric acid), for example, and then the resist 21 (in this case, resisting resistance is obtained by chemical treatment such as etching using NaOH or KOH). (Hydrofluoric acid) is removed.

  Alternatively, the modified regions 7A and 7B and the resist 21 are removed by chemical treatment such as etching using HF (hydrofluoric acid), for example. In this way, if a plurality of processes are performed simultaneously by one chemical process, the number of processing steps can be reduced.

  As described above, in the laser processing method of the first embodiment, after the resist 21 is formed on the front surface 1a and the back surface 1b of the processing target 1, processing for cutting out the effective portion 17 from the processing target 1 is performed. Thereafter, the modified regions 7A and 7B existing on the side surface 19 of the effective portion 17 are removed, and the resist 21 existing on the front surface 17a and the back surface 17b of the effective portion 17 is removed. Therefore, the front surface 17a and the back surface 17b of the effective portion 17 are protected by the resist 21 during processing, and the modified regions 7A and 7B that cause a decrease in the bending strength are removed from the cut out effective portion 17. Therefore, according to the laser processing method of the first embodiment, it is possible to suppress the bending strength from being lowered in the effective portion 17 cut out from the workpiece 1 and to reduce the outer surface of the effective portion 17 during processing. Can be protected.

Further, when the modified regions 7A and 7B are formed, the laser beam L is incident on the workpiece 1 through the resist 21 formed so as to cover the entire area of the front surface 1a and the back surface 1b of the workpiece 1. . In this manner, by using the resist 21 that can transmit the laser light L, patterning of the resist 21 becomes unnecessary, so that the number of processing steps can be reduced.
[Second Embodiment]

  The laser processing method of the second embodiment is mainly different from the laser processing method of the first embodiment described above in that the workpiece 1 includes an unstrengthened glass plate 20 (that is, a normal glass (float glass) plate). It is different. In the laser processing method according to the second embodiment, first, as shown in FIG. 13, a workpiece 1 including an unstrengthened glass plate 20 is prepared, and as shown in FIG. 14, the front surface 1 a and the back surface of the workpiece 1. A resist 21 is formed on the front surface 1a and the back surface 1b so as to cover the entire region 1b (first step).

  After forming the resist 21, as shown in FIG. 15, the surface 1a of the workpiece 1 is used as the laser beam incident surface, the condensing point of the laser beam L is located inside the unstrengthened glass plate 20, and each cutting planned line The workpiece 1 is irradiated with the laser beam L along the lines 51 and 52. That is, the condensing point of the laser beam L is relatively moved (scanned) along the scheduled cutting lines 51 and 52. At this time, the laser beam L is incident on the processing target 1 through the resist 21 formed on the surface 1 a of the processing target 1. Thus, the modified regions 7A and 7B that generate the crack 80 extending in the thickness direction of the workpiece 1 are formed in the unstrengthened glass plate 20 along the scheduled cutting lines 51 and 52 (second step). ).

  Then, by applying an external force along the planned cutting lines 51 and 52 and extending the crack 80 generated from the modified regions 7A and 7B in the thickness direction of the workpiece 1, the planned cutting lines 51 and 52 are formed. The workpiece 1 and the resist 21 are cut along the cut, and a plurality of effective portions 17 are cut out from the workpiece 1 (second step). As shown in FIG. 16, the modified regions 7A and 7B exist on the side surface 19 of the cut out effective portion 17, and the resist 21 exists on the front surface 17a and the back surface 17b of the cut out effective portion 17. doing.

  After cutting out the effective portion 17, the modified regions 7A and 7B existing on the side surface 19 of the effective portion 17 are removed as shown in FIG. 17, and the front surface 17a and the back surface 17b of the effective portion 17 are removed as shown in FIG. Is removed, the unstrengthened glass plate 20 is strengthened (third step), and a plate-shaped effective portion 17 including the strengthened glass plate 10 is obtained as shown in FIG.

  More specifically, the modified regions 7A and 7B are removed by mechanical polishing using a polishing tool or the like, and then the resist 21 is removed by chemical treatment such as etching using NaOH or KOH, for example, an ion exchange method. The unstrengthened glass plate 20 is strengthened by chemical treatment such as the above. Alternatively, the modified regions 7A and 7B are removed by chemical treatment such as etching using HF (hydrofluoric acid), for example, and then the resist 21 (in this case, resisting resistance is obtained by chemical treatment such as etching using NaOH or KOH). Hydrofluoric acid) is removed, and the unstrengthened glass plate 20 is strengthened by chemical treatment such as ion exchange.

  Alternatively, the modified regions 7A and 7B and the resist 21 are removed by chemical treatment such as etching. Alternatively, the resist 21 is removed and the unstrengthened glass plate 20 is strengthened by chemical treatment. Alternatively, the modified regions 7A and 7B are removed, the resist 21 is removed, and the unstrengthened glass plate 20 is strengthened by chemical treatment. In this way, if a plurality of processes are performed simultaneously by one chemical process, the number of processing steps can be reduced.

  As described above, in the laser processing method according to the second embodiment, after forming the resist 21 on the front surface 1a and the back surface 1b of the processing target 1, processing for cutting out the effective portion 17 from the processing target 1 is performed. Thereafter, the modified regions 7A and 7B existing on the side surface 19 of the effective portion 17 are removed, and the resist 21 existing on the front surface 17a and the back surface 17b of the effective portion 17 is removed. Therefore, according to the laser processing method of the second embodiment, the same effects as those of the laser processing method of the first embodiment are exhibited.

  Although the first and second embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments. For example, the shapes of the processing object and the effective portion are not limited to a rectangular plate shape, and various shapes can be applied. Moreover, you may cut out one effective part from a process target object.

  In addition, a plurality of rows of modified regions may be formed so as to be aligned in the thickness direction of the workpiece with respect to each scheduled cutting line. Even in such a case, according to the present invention, it is possible to suppress the bending strength from being lowered in the effective portion cut out from the workpiece, and to protect the outer surface of the effective portion during processing. The number of columns of the modified region for one scheduled cutting line can be determined as appropriate according to the thickness of the workpiece.

  In the above embodiment, after the modified region is formed, an external force is applied along the planned cutting line to cause the cracks generated from the modified region to reach the front and back surfaces of the workpiece, thereby cutting. Although the workpiece was cut along the planned line, the present invention is not limited to this. That is, with the formation of the modified region for each planned cutting line (without applying any external force to the workpiece), the cracks generated from the modified region reach the front and back surfaces of the workpiece, You may cut | disconnect protective films, such as a resist, with a thing. In addition, when an external force is applied along the planned cutting line, only a crack is generated along with the formation of the modified region, and only the crack reaches the one of the front surface and the back surface of the workpiece. Alternatively, it is not necessary to cause cracks to reach both the front and back surfaces of the workpiece.

  The object to be processed may be one in which a resin film or the like is formed on at least one of the front and back surfaces of the tempered glass plate, or a resin film or the like is formed on at least one of the front and back surfaces of the unreinforced glass plate. It may be what was done. In addition, as the modified region, a melt-processed region, a crack region, a dielectric breakdown region, a refractive index change region, or a region in which these are mixed is formed depending on the irradiation condition of the laser beam.

  Moreover, in the said embodiment, although the laser beam L was made to inject into the process target object 1 via the resist 21 formed in the surface 1a of the process target object 1, the resist formed in the back surface 1b of the process target object 1 The laser beam L may be incident on the workpiece 1 via 21.

  Further, a resist 21 is formed on at least one of the front surface 1a and the back surface 1b of the workpiece 1 so as to cover a region other than the regions along the scheduled cutting lines 51 and 52 (for example, the resist 21 is formed by a photolithography technique). Patterning), and then, the laser beam L may be incident on the workpiece 1 through the regions along the planned cutting lines 51 and 52. According to this, for example, it is possible to use a resist 21 made of a material having low transmittance of the laser light L, such as a black matrix (a metal chromium film or a light-shielding resin black material). The degree of freedom of selection can be increased.

  DESCRIPTION OF SYMBOLS 1 ... Processing target object, 1a ... Front surface, 1b ... Back surface, 7A, 7B ... Modified region, 10 ... Tempered glass plate, 17 ... Effective part, 17a ... Front surface, 17b ... Back surface, 19 ... Side surface, 20 ... Unreinforced glass Plate, 21: Resist (protective film), 51, 52: Planned cutting line, 80: Crack, L: Laser beam, P: Focusing point.

Claims (12)

A laser processing method for cutting out an effective portion from a plate-like processing object including a glass plate,
A first step of forming a protective film on the front and back surfaces of the workpiece;
After the first step, the glass is moved along the planned cutting line by relatively moving a condensing point of the laser light along the planned cutting line extending along the side surface of the effective portion. Forming a modified region inside the plate, and extending a crack generated from the modified region in the thickness direction of the workpiece, thereby cutting out the effective portion from the workpiece;
After the second step, a third step of removing the modified region existing on the side surface of the effective portion and removing the protective film existing on the front surface and the back surface of the effective portion, laser processing Method. In the first step, the protective film is formed so as to cover the entire area of the front surface and the back surface of the workpiece,
The laser processing method according to claim 1, wherein, in the second step, the laser light is incident on the processing object through the protective film formed on the front surface or the back surface of the processing object. In the first step, in at least one of the front surface and the back surface of the workpiece, the protective film is formed so as to cover a region other than a region along the planned cutting line,
2. The laser processing method according to claim 1, wherein in the second step, the laser beam is incident on the object to be processed through the region along the planned cutting line.   The laser processing method according to claim 1, wherein the glass plate is a tempered glass plate.   The laser processing method according to claim 4, wherein in the third step, the modified region is removed by mechanical polishing, and then the protective film is removed.   The laser processing method according to claim 4, wherein in the third step, the modified region is removed by chemical treatment, and then the protective film is removed.   The laser processing method according to claim 4, wherein in the third step, the modified region is removed by chemical treatment and the protective film is removed. The glass plate is an unstrengthened glass plate,
The laser processing method according to claim 1, wherein in the third step, the glass plate is strengthened.   The laser processing method according to claim 8, wherein, in the third step, the modified region is removed by mechanical polishing, and then the protective film is removed to strengthen the glass plate.   The laser processing method according to claim 8, wherein, in the third step, the modified region is removed by chemical treatment, and then the protective film is removed to strengthen the glass plate.   The laser processing method according to claim 8, wherein in the third step, the modified region is removed by chemical treatment and the protective film is removed.   The laser processing method according to claim 8, wherein in the third step, the protective film is removed by chemical treatment and the glass plate is strengthened.

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