JP2011230940A - Cutting method for brittle material substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method capable of cutting a brittle material substrate along two directions intersecting with each other, by an existing cutter using a laser beam.SOLUTION: This method includes a first process for irradiating the brittle material substrate 50 with the laser beam LB, while moved relatively each other, to heat the substrate 50 up to a temperature less than a melting temperature, for thereafter blowing a cooling medium to the substrate 50 to cool the substrate, and for forming a first scribe line 52a formed of a vertical crack 53a, by a thermal stress generated in the substrate, a second process for preheating an intersecting portion of the first scribe line 52a with a second scribe planned line 51b, up to the temperature less than the melting temperature of the substrate 50, a third process for forming the second scribe line 52b intersecting with the first scribe line 52a, and a fourth process for cutting the substrate 50 along the first scribe line 52a and the second scribe line 52b.

Description

  The present invention relates to a method of irradiating a brittle material substrate with a laser beam and cleaving the brittle material substrate along two directions intersecting each other.

  Conventionally, as a method for cleaving a brittle material substrate such as a glass substrate, a scribe line is formed by pressing and rolling a cutter wheel or the like, and then the substrate is cleaved by applying external force from the direction perpendicular to the substrate along the scribe line. The method is widely practiced.

  Usually, when a brittle material substrate is scribed using a cutter wheel, the substrate is likely to be defective due to mechanical stress imparted to the brittle material substrate by the cutter wheel, and is caused by the above-described defect when performing a break. Cracks occur.

  Therefore, in recent years, a method of cleaving a brittle material substrate using a laser has been put into practical use. In this method, the substrate is irradiated with a laser beam to heat the substrate to a temperature lower than the melting temperature, and then the substrate is cooled by a cooling medium, thereby generating thermal stress on the substrate. To form cracks. In this method of cleaving a brittle material substrate using a laser beam, since the thermal stress is used, the tool is not brought into direct contact with the substrate, the fractured surface becomes a smooth surface with few chips and the strength of the substrate is maintained. The

  In addition, a method of cleaving a brittle material substrate in two directions intersecting each other using a laser has been proposed. However, when cutting the brittle material substrate in the first direction and then cutting the brittle material substrate in the second direction that intersects the first direction, vertical cracks do not develop from the intersection with the first direction, or There was a case where a vertical crack developed from the planned cutting line. In particular, in the case of tempered glass having a high surface compressive stress, the vertical cracks formed in the first direction are maintained in a largely open state. Therefore, when cutting the brittle material substrate in the second direction, It is difficult for cracks to advance from the intersection with the direction.

  For this reason, for example, in Patent Document 1, the brittle material substrate is irradiated with a laser beam to cut the brittle material substrate in the first direction, and then the upper surface of the support base that supports the brittle material substrate is changed into a concave shape. A method has been proposed in which the cut portions of the material substrate are pressed against each other, and a laser beam is irradiated in this state to cut the brittle material substrate in a second direction orthogonal to the first direction.

WO2006 / 90632

  However, in order to implement the proposed method, a special cutting device having a complicated mechanism for changing the shape of the upper surface of the support base for supporting the brittle material substrate is required.

  The present invention has been made in view of such conventional problems, and an object of the present invention is to provide a method capable of cleaving a brittle material substrate in two directions intersecting each other with an existing cutting device using a laser. is there.

  The method for cleaving a brittle material substrate according to the present invention that achieves the above object is to irradiate the brittle material substrate while moving the laser beam relative to the brittle material substrate, heat the substrate to below the melting temperature, A cooling medium is sprayed to cool, and a crossing portion between the first scribe line and the second scribe line of the first scribe line is formed by the thermal stress generated on the substrate to form the first scribe line composed of vertical cracks. A second step of preheating below the melting temperature of the substrate, a third step of forming a second scribe line that intersects the first scribe line in the same manner as the first scribe line, and the first scribe line and the second scribe line And a fourth step of cleaving the substrate along the line.

  Here, from the viewpoint of productivity or the like, the preheating is preferably performed by laser beam irradiation.

  Further, the length of the portion to be preheated in the direction parallel to the first scribe line is preferably in the range of 1 to 5 mm.

  A tempered glass substrate is preferable as the brittle material substrate.

  According to the method for cleaving a brittle material substrate according to the present invention, the brittle material substrate can be cleaved in two directions intersecting each other without using a cutting device having a special mechanism.

It is an outline figure showing an example of a cleaving device which can carry out a cleaving method concerning the present invention. It is a figure explaining the operation state of a laser scribe. It is process drawing which shows an example of the cleaving method which concerns on this invention. It is process drawing which shows an example of the cleaving method which concerns on this invention. It is a schematic diagram of the irradiation spot of a laser beam. 2 is an optical micrograph of an intersection portion of a first scribe line and a second scribe line in Example 1. 6 is a photograph of a substrate in Comparative Example 1 where a vertical crack has progressed out of the second scribe line.

  Hereinafter, although the cutting method of the brittle material substrate according to the present invention will be described with reference to the drawings, the present invention is not limited to these embodiments.

  FIG. 1 is a schematic view showing an example of a cleaving apparatus used for carrying out the cleaving method according to the present invention. The cleaving apparatus in this figure includes a slide table 12 that is movable on the gantry 11 in a direction perpendicular to the paper surface (Y direction), a pedestal 19 that is movable on the slide table in the left and right direction (X direction), and The brittle material substrate 50 provided with a rotating mechanism 25 provided on the pedestal 19 and placed and fixed on the rotating table 26 provided on the rotating mechanism 25 is freely moved in the horizontal plane by these moving means. The

  The slide table 12 is movably mounted on a pair of guide rails 14 and 15 arranged in parallel with a predetermined distance on the upper surface of the gantry 11. Between the pair of guide rails 14 and 15, a ball screw 13 is provided in parallel to the guide rails 14 and 15 so as to be rotatable forward and backward by a motor (not shown). A ball nut 16 is provided on the bottom surface of the slide table 12. The ball nut 16 is screwed into the ball screw 13. When the ball screw 13 rotates forward or backward, the ball nut 16 moves in the Y direction, whereby the slide table 12 to which the ball nut 16 is attached moves on the guide rails 14 and 15 in the Y direction.

  The pedestal 19 is movably supported by a pair of guide members 21 disposed in parallel on the slide table 12 at a predetermined distance. Between the pair of guide members 21, a ball screw 22 is provided in parallel with the guide member 21 so as to be rotatable forward and backward by a motor 23. A ball nut 24 is provided on the bottom surface of the pedestal 19 and is screwed into the ball screw 22. When the ball screw 22 rotates forward or backward, the ball nut 24 moves in the X direction, whereby the pedestal 19 together with the ball nut 24 moves in the X direction along the pair of guide members 21.

  A rotation mechanism 25 is provided on the pedestal 19. A rotating table 26 is provided on the rotating mechanism 25. The brittle material substrate 50 to be cleaved is fixed on the rotary table 26 by vacuum suction. The rotation mechanism 25 rotates the rotary table 26 around the central axis in the vertical direction.

  A support base 31 is supported above the rotary table 26 by a holding member 33 that hangs down from the mounting base 32 so as to face the rotary table 26 at a distance. The support base 31 includes a cutter wheel 35 for forming a trigger crack on the surface of the brittle material substrate 50, an opening (not shown) for irradiating the brittle material substrate 50 with a laser beam, and the surface of the brittle material substrate 50. And a cooling nozzle 37 for cooling.

  The cutter wheel 35 is held by the chip holder 36 so as to be movable up and down between a position in pressure contact with the brittle material substrate 50 and a non-contact position, and the brittle material is formed only when a trigger crack is formed as a starting point of the scribe line. It descends to a position where it comes into pressure contact with the substrate 50. The trigger crack is preferably formed on the inner side of the edge of the brittle material substrate 50 in order to suppress a pre-cursor phenomenon in which the crack is generated in an unpredictable direction from the trigger crack.

  A laser output device 34 is provided on the mounting base 32. The laser beam LB emitted from the laser output device 34 is reflected downward by the reflection mirror 44, and is formed on the rotary table 26 from the opening formed in the support base 31 through the optical system held in the holding member 33. The fixed brittle material substrate 50 is irradiated.

  Further, water as a cooling medium is ejected together with air from the cooling nozzle 37 provided in the vicinity of the opening of the support base 31 where the laser beam LB is emitted toward the brittle material substrate 50. The position on the brittle material substrate 50 from which the cooling medium is ejected is on the planned cutting line 51 and behind the irradiation region of the laser beam LB (see FIG. 2).

  The mounting base 32 is provided with a pair of CCD cameras 38 and 39 for recognizing alignment marks engraved in advance on the brittle material substrate 50. These CCD cameras 38 and 39 detect misalignment when the brittle material substrate 50 is set. For example, when the brittle material substrate 50 is deviated by an angle θ, the rotary table 26 is rotated by −θ. When Y is misaligned, the slide table 12 is moved by -Y.

  When the brittle material substrate 50 is cleaved in the cleaving apparatus having such a configuration, first, the brittle material substrate 50 is placed on the rotary table 26 and fixed by suction means. Then, the CCD camera 38, 39 images the alignment mark provided on the brittle material substrate 50, and positions the brittle material substrate 50 at a predetermined position based on the imaging data as described above.

  Next, as described above, a trigger crack is formed in the brittle material substrate 50 by the wheel cutter 35. Then, a laser beam LB is emitted from the laser output device 34. The laser beam LB is irradiated by the reflecting mirror 44 substantially perpendicularly to the surface of the brittle material substrate 50 as shown in FIG. At the same time, water as a cooling medium is ejected from the cooling nozzle 37 in the vicinity of the rear end of the laser beam irradiation region. By irradiating the brittle material substrate 50 with the laser beam LB, the brittle material substrate 50 is heated below the melting temperature in the thickness direction, and the brittle material substrate 50 tries to thermally expand, but cannot expand due to local heating, and the irradiation point Compressive stress is generated around the center. Immediately after the heating, the surface of the brittle material substrate 50 is cooled by water, so that the brittle material substrate 50 is contracted and tensile stress is generated. Due to the action of the tensile stress, the vertical crack 53 is formed in the brittle material substrate 50 along the planned cutting line 51 with the trigger crack as a starting point.

  Then, by moving the laser beam LB and the cooling nozzle 37 relative to each other according to the planned cutting line 51, the vertical crack 53 is developed and the scribe line 52 is formed on the brittle material substrate 50. In the case of this embodiment, the brittle material substrate 50 is moved by the slide table 12, the pedestal 19, and the rotating mechanism 25 of the rotating table 26 while the laser beam LB and the cooling nozzle 37 are fixed at predetermined positions. . Of course, the laser beam LB and the cooling nozzle 37 may be moved while the brittle material substrate 50 is fixed. Alternatively, both the brittle material substrate 50 and the laser beam LB / cooling nozzle 37 may be moved.

  Next, the cleaving method according to the present invention will be described. FIG. 3 is a process diagram showing an example of the cleaving method of the present invention. First, as shown in FIG. 5A, as described above as the first step, the laser beam LB and the cooling nozzle 37 are relatively moved according to the planned cutting line 51a, so that a trigger crack (not shown) is started. The first scribe line 52a is formed on the brittle material substrate 50 by causing the vertical crack 53a to propagate in the relative movement direction.

The laser beam LB used here is not particularly limited, and may be determined appropriately from the material and thickness of the substrate, the depth of the vertical crack to be formed, and the like. When the brittle material substrate is a glass substrate, a laser beam having a wavelength of 9 to 11 μm, which has a large absorption on the glass substrate surface, is preferably used. An example of such a laser beam is a CO ₂ laser. As shown in FIG. 5, the irradiation shape of the laser beam on the substrate is preferably an elliptical shape elongated in the relative movement direction of the laser beam, the irradiation length L in the relative movement direction is in the range of 10 to 60 mm, and the irradiation width W is A range of 1-5 mm is preferred.

  Examples of the cooling medium ejected from the cooling nozzle 37 include water and alcohol. Further, an additive such as a surfactant may be added within a range that does not adversely affect the use of the brittle material substrate after cleaving. Usually, the amount of cooling medium sprayed is preferably about several ml / min. The cooling of the substrate by the cooling medium is preferably a so-called water jet method in which water is injected together with gas (usually air) from the viewpoint of rapidly cooling the substrate heated by the laser beam. The cooling region with the cooling medium is preferably circular or elliptical with a major axis of about 1 to 5 mm. The cooling region is preferably formed so that the distance between the center points of the cooling region and the heating region is about several millimeters to several tens of millimeters behind the relative movement direction of the heating region by the laser beam.

  The relative moving speed of the laser beam LB and the cooling nozzle 37 is not particularly limited, and may be appropriately determined from the depth of the vertical crack to be obtained. In general, the slower the relative movement speed, the deeper the vertical cracks that are formed. Usually, the relative movement speed is about several hundred mm / sec.

  The depth of the vertical crack 53a constituting the scribe line 52a is not particularly limited. However, in order to smoothly and reliably cut the brittle material substrate in the subsequent process, the depth is set to 15% or more with respect to the substrate thickness. Is desirable.

  Next, as shown in FIG. 3B, as a second step, the planned splitting line 51b is formed by relatively moving the laser beam LB along the second scribe planned line 51b orthogonal to the first scribe line 52a. Preheat. The preheated portion of the brittle material substrate is thermally expanded, the opposing end surfaces of the vertical cracks 53a of the first scribe line 52a are pressed against each other, and the first scribe line 52a apparently disappears partially. The irradiation condition of the laser beam LB in the preheating is not limited as long as the brittle material substrate 50 expands by heating and the opposite end faces of the first scribe line 52a are in pressure contact with each other, and the material of the brittle material substrate 50 and the first scribe line are not limited. What is necessary is just to determine suitably from the depth etc. of the vertical crack 53a of the line 52a. For example, when a laser beam LB with an output of 100 to 200 W is used, the relative speed is usually preferably in the range of 200 to 500 mm / sec. Further, the length of the portion to be preheated in the direction parallel to the first scribe line 52a, that is, the irradiation width W of the laser beam LB (see FIG. 5) is preferably in the range of 1 to 5 mm.

  The preliminary heating with the laser beam LB may be performed by heating at least the intersecting portion of the first scribe line 52a and the second scribe line 51b, and it is not necessary to heat the entire second scribe line 51b. When preheating only the intersection of the first scribe line 52a and the second scribe line 51b, the laser beam output is controlled to be turned on and off, and the brittle material substrate 50 is moved relative to the intersection. It is only necessary to turn on the output of the laser beam LB.

  Further, the heat source for the preheating is not limited to the laser beam LB, and conventionally known heating means such as infrared rays can be used. However, since the minute range can be efficiently heated in a short time, the laser beam LB is used. Heating is preferred.

  Next, as shown in FIG. 3C, as the third step, the laser beam LB and the cooling nozzle 37 are relatively moved along the second scribe line 51b orthogonal to the first scribe line 52a. Two scribe lines 52b are formed. Here, conventionally, the second scribe line 52b has not advanced first from the intersection with the first scribe line 52a, or has progressed away from the second scribe planned line 51b, but in the cleaving method of the present invention, In the second step, since the crossing portion is heated and the brittle material substrate 50 is thermally expanded, the opposing end surfaces of the first scribe line 52a are brought into pressure contact with each other, so the second scribe line 52b is connected to the first scribe line 52a. It progresses ahead along the second scribe line 51b beyond the intersection. The conditions for forming the second scribe line 52b are the same as the conditions for forming the first scribe line 52a.

  Next, as shown in FIG. 4D, as the fourth step, the laser beam LB is irradiated again along the second scribe line 52b. As a result, the vertical crack 53b develops in the substrate thickness direction, and the substrate 50 is cleaved by the second scribe line 52b. Note that the vertical crack 53 b only needs to extend to a depth at which the substrate 50 is cleaved without applying an external force, and does not necessarily have to reach the opposite surface side of the substrate 50.

  Irradiation conditions of the laser beam LB for causing the vertical crack 53b to propagate in the substrate thickness direction may be determined as appropriate from the thickness of the substrate 50, the depth of the vertical crack 53b, and the like. Usually, the second scribe line 52b described above is used. The irradiation conditions when forming are also exemplified here. The relative movement direction of the laser beam LB is preferably opposite to the direction in which the second scribe line 52b is formed.

  Next, as shown in FIG. 5E, the laser beam LB is irradiated again along the first scribe line 52a. As a result, the vertical crack 53a develops in the substrate thickness direction, and the substrate 50 is cleaved by the first scribe line 52a. Similarly to the vertical crack 53b, the depth of the vertical crack 53a after the progress is not limited as long as the vertical crack 53a has progressed to a depth at which the substrate 50 is cleaved without applying an external force. It is not necessary to reach the opposite side of the.

  The irradiation condition of the laser beam LB for causing the vertical crack 53a to propagate in the substrate thickness direction may be determined as appropriate from the thickness of the substrate 50, the depth of the vertical crack 53a, and the like. The irradiation conditions when forming are also exemplified here. In addition, the relative movement direction of the laser beam LB is preferably opposite to the direction in which the first scribe line 52a is formed.

  Note that the fourth step of cutting the brittle material substrate 50 along the first scribe line 52a and the second scribe line 52b shown in FIGS. 4D and 4E is performed after the first scribe line 52a is cut. The second scribe line 52b may be cleaved, but it is preferable to cleave the first scribe line 52a after the second scribe line 52b is cleaved as in the above embodiment. Further, the cleaving of the brittle material substrate in the fourth step is not limited to the cleaving by re-irradiation with the laser beam LB, but mechanically cleaves by applying an external force in a direction substantially perpendicular to the surface of the brittle material substrate 50. A conventionally known method such as a method for performing the method can be used.

  The brittle material substrate 50 to which the cleaving method of the present invention can be applied is not particularly limited, and includes conventionally known brittle material substrates such as glass, ceramic, silicon, and sapphire. Among these, the cleaving method of the present invention can be suitably applied to tempered glass substrates such as chemically tempered glass and air-cooled tempered glass that have a large surface compressive stress and are difficult to cross-scribe. In addition, the thickness of the brittle material substrate 50 to which the cleaving method of the present invention can be applied varies depending on the material of the brittle material substrate 50 and the like, but is approximately 2 mm when the brittle material substrate 50 is a glass substrate.

  As described above, in each of the embodiments described above, each of the first scribe line 52a and the second scribe line 52b is formed to cleave the substrate. However, the first scribe line 52a and the second scribe line 52a are formed on the substrate 50 having a large area. Of course, the cleaving method of the present invention can also be applied to a case where a plurality of lines 52b are formed and cleaved into a large number of small area substrates. In addition, the cleaving method of the present invention can be applied to a case where the two scribe lines are crossed at a desired angle in addition to the case where the two scribe lines are orthogonal.

Example 1
A first scribe line was formed by performing laser irradiation and cooling on a chemically strengthened glass substrate having a thickness of 0.55 mm using the cleaving apparatus shown in FIG. 1 (first step). Specific conditions for laser irradiation and cooling are as follows. Next, laser irradiation was performed along a second scribe line orthogonal to the first scribe line to perform preheating. The laser irradiation conditions in the preheating are the same as the laser irradiation conditions when forming the first scribe line. Thereafter, laser irradiation and cooling were performed along the second scribe line to form a second scribe line (third step). The specific conditions of laser irradiation and cooling in forming the second scribe line are the same as the laser irradiation and cooling conditions in forming the first scribe line.
(Laser irradiation and cooling conditions for the first and second scribe lines)
Laser beam: CO ₂ laser Laser output: 200 W to 250 W
Relative moving speed: 130mm / sec to 150mm / sec

(result)
FIG. 6 shows an optical micrograph of the intersection of the first scribe line and the second scribe line. FIG. 6A shows the first scribe line after formation, FIG. 6B shows the preheating, and FIG. 10C shows the second scribe line. As can be understood from FIG. 5B, when the pre-heating is performed along the second scribe line after the first scribe line is formed, a vertical crack is generated in the portion where the pre-heating of the first scribe line is performed. Apparently disappeared. As is clear from FIG. 6C, when laser irradiation and cooling are performed along the second scribe line, the second scribe line crosses the intersection of the first scribe lines and becomes the second scribe line. Formed along.

Comparative Example 1
The first scribe line and the second scribe line were formed in the same manner as in Example 1 except that no preheating was performed. In the second scribe line forming step, the first scribe line was perpendicular to the intersection with the first scribe line. The crack progressed off the second scribe line. FIG. 7 shows a photograph of the substrate on which the vertical crack has progressed out of the second scribe line.

  According to the cleaving method of the present invention, the brittle material substrate can be cleaved in two directions intersecting each other without using a cutting device having a special mechanism.

37 Cooling nozzle 50 Brittle material substrate 51, 51a, 51b Planned cutting line 52 Scribe line 52a First scribe line 52b Second scribe line 53, 53a, 53b Vertical crack LB Laser beam

Claims (4)

  Irradiating the brittle material substrate while relatively moving the laser beam, heating the substrate below the melting temperature, cooling the substrate by spraying a cooling medium, and by the thermal stress generated on the substrate, A first step of forming a first scribe line composed of vertical cracks; a second step of preheating the intersection of the first scribe line with the second scribe line to be below the melting temperature of the substrate; A third step of forming a second scribe line that intersects the first scribe line, and a fourth step of cleaving the substrate along the first scribe line and the second scribe line in the same manner as the line. A method for cleaving a brittle material substrate.   The cleaving method according to claim 1, wherein the preliminary heating is performed by laser beam irradiation.   The cleaving method according to claim 1 or 2, wherein a length of the portion to be preheated is in a range of 1 to 5 mm in a direction parallel to the first scribe line.   The cleaving method according to claim 1, wherein the brittle material substrate is a tempered glass substrate.