TWI466749B - Method for Segmentation of Fragile Material Substrate - Google Patents

Description

Method for dividing brittle material substrate

The present invention relates to a method of dividing a brittle material substrate by irradiating a laser beam. Here, the brittle material substrate includes a glass substrate, a sapphire substrate, a ceramic of a sintered material, a single crystal germanium, a semiconductor wafer, a ceramic substrate, or the like.

In the case of a brittle material substrate such as glass, a substrate division method is employed in which a laser is irradiated along a predetermined dividing line set on a substrate to form a crack (the material of the processed portion is not removed) or a groove (the material of the processed portion is removed). And, the fracture process is performed along the formed cracks or grooves, thereby dividing the substrate.

Fig. 12 is a schematic cross-sectional view showing an example of a groove or a crack formed in a substrate by laser irradiation. Fig. 12(a) shows a groove formed by laser ablation processing, Fig. 12(b) shows a groove formed by laser ablation processing, and a crack, and Fig. 12(c) shows a line marked by laser The crack formed by the processing.

In the laser ablation processing, a laser beam such as a UV laser beam is scanned along a predetermined dividing line, and heated at a temperature equal to or higher than the melting temperature of the substrate to be evaded, thereby forming the groove 101, or forming not only the groove 101 but also the induced beam. A crack 102 at the bottom of the groove 101.

Further, in the laser scribing process, a laser beam such as a CO ₂ laser is irradiated onto the substrate to be processed to form a beam spot on the processed surface, and the beam spot is scanned to be along the dividing line at a temperature lower than the softening point. Heating is performed, followed by cooling along the trajectory of the beam spot. Thereby, the crack 103 is formed according to the stress difference between the compressive stress generated around the heating portion and the tensile stress generated around the cooling portion (for example, refer to Patent Document 1).

Then, along the groove 101 (or the groove 101 and the crack 102) formed by the laser ablation processing, or the crack 103 formed by laser scribing, from the back side R of the substrate (grooves or cracks are formed) The opposite side of the surface is subjected to a fracture treatment by applying a bending moment M (breaking pressure), whereby the cracks 102, 103 or the grooves 101 are extended in the thickness direction to divide the substrate.

In general, when the brittle material substrate is divided, in order to perform the fracture treatment simply and reliably with a small bending moment (breaking pressure), it is preferable to form a deep crack or groove as much as possible in the thickness direction. Further, in order to reduce the occurrence of the "notch" of the split surface and to improve the quality of the split surface, it is preferable to form a deep crack or groove in the thickness direction in advance.

However, in laser ablation processing, deep grooves (or grooves and cracks) can be formed in terms of technology, but since the depth of the groove is roughly proportional to the processing time, if a deep groove is to be formed, it is necessary to Long processing time. However, when the ablation processing is performed, the longer the processing time, the more the amount of the substrate material evaporated from the portion where the groove is formed, which contaminates the surface of the surrounding substrate. Therefore, it is not practical to form a deep groove from the viewpoint of processing time and substrate contamination. Therefore, it is desirable to divide by a shallow groove.

On the other hand, in laser scribing, the substrate material does not evade, so there is no problem of substrate contamination. However, due to the thermal strain generated inside the substrate, the crack is prevented from extending deeper. sleepy difficult. Hereinafter, the influence of the thermal strain in the substrate which hinders the crack extension will be described.

Fig. 13 is a schematic cross-sectional view showing a thermal strain distribution generated in a substrate when laser beam is irradiated onto the substrate at a temperature equal to or lower than the softening temperature of the substrate, and the beam spot is scanned and then cooled. In the figure, the laser beam continuously moves from the inner side of the paper surface to the near side of the paper surface.

As shown in Fig. 13 (a), the portion 100 heated by the beam spot of the laser beam generates a compressive stress in the direction indicated by the dotted arrow in the figure. Then, as shown in FIG. 13(b), when the cooling point 110 is formed by spraying the refrigerant in the vicinity of the portion 100 heated by the passage of the beam spot, a solid arrow is formed as shown in the figure. Tensile stress.

Therefore, as shown in FIG. 13(c), cracks 120 extending in the thickness direction of the substrate in a direction perpendicular to the tensile stress are formed in accordance with the stress difference.

However, even if the cooling point 110 is formed, a portion which generates a stress difference sufficient to form the crack 120 is limited to the surface portion of the substrate. If the heat diffused from the cooling point 110 toward the thickness direction of the substrate and the heat diffused from the heated portion 100 toward the thickness of the substrate are not sufficient to form a stress difference of the crack 120, that is, a temperature difference, It is considered that the remaining heat diffused from the heated portion 100 in the thickness direction of the substrate causes the compressive stress region 130 to remain in the substrate. The compressive stress region 130 is defined as the relative thermal strain within the substrate.

As shown in Fig. 13(c), the compressive stress region 130 prevents the crack 120 from extending vertically vertically in the thickness direction of the substrate. Thus When the laser beam is scanned at a practical speed on the surface of the brittle material substrate, the extent of the crack 120 in the thickness direction is about 2 to 40% of the thickness of the plate.

Therefore, when the beam spot is continuously scanned along the crack forming planned line (the direction perpendicular to the paper surface in Fig. 13), the substrate is continuously heated along the line without interruption, and compressive stress is continuously formed inside the substrate. The region, therefore, due to the existence of the region of compressive stress, in principle, it is difficult to form a deep crack directly below the predetermined line of crack formation.

On the other hand, there is also disclosed a crack forming method in which, in the laser scribing process, a predetermined line (divided line of division) is formed along the crack to alternately form a high temperature portion which is strongly irradiated by the laser beam, and The irradiation of the laser beam is weaker than the low temperature portion of the high temperature portion, whereby a deep crack is vertically extended straight (refer to Patent Document 2).

Patent Document 2 discloses that when a predetermined line is irradiated along a crack to irradiate a laser beam to form a crack on the surface of the brittle substrate, the surface of a portion of the brittle substrate on the predetermined line of crack formation is shielded from light to form an area not irradiated with the laser beam. , this will produce the following phenomenon.

That is, it has been found that if the shading length of the laser beam (the length of the shading portion in the direction in which the crack is formed in the predetermined line direction) is large, the crack stops at the shading portion, but if the shading length is gradually reduced, the final shading is performed. Cracks are continuously formed in the portion, and the depth of the crack formed by the light-shielding portion becomes deep.

In the above phenomenon, the light-shielding portion is defined as a low-temperature portion and the non-light-shielding portion is defined as a high-temperature portion with respect to the non-light-shielding portion. By The length of the low temperature portion in the direction in which the crack is formed is appropriate, and the thermal strain is suppressed in the low temperature portion, so that the vertical crack continuously formed in the high temperature portion is not interrupted at a low temperature portion, and a deep crack can be formed, and The crack is directed to illuminate a high temperature portion below the laser beam.

That is, by sizing the length of the low temperature portion in the direction of the predetermined line of crack formation (so that the crack is not interrupted at a low temperature portion and extending the length of the low temperature portion as much as possible), there is no compressive stress region inside the substrate, or even if present The compressive stress region can also suppress the occurrence of the compressive stress region to a minimum, so that a straight and deep continuous crack can be formed with high precision in the thickness direction in the low temperature portion and the high temperature portion. Thereby, the breaking device for dividing the brittle substrate can be simplified, and the breaking device can be omitted.

[Patent Document 1] Japanese Patent No. 3027768 (Patent Document 2) WO2006/11608

As described in Patent Document 2, when a predetermined line (divided line to be divided) is formed along a crack, a high-temperature portion that is strongly irradiated with a laser beam is alternately formed with an appropriate length, and the irradiation with the laser beam is weaker than the high temperature. Part of the low temperature portion allows the crack to be extended vertically and straightly deep so that the subsequent fracture treatment can be easily performed.

However, in order to carry out the method, it is necessary to set the high temperature region and the low temperature region to an appropriate interval in advance at the time of laser scribing (crack formation), and for this, it is necessary to set or adjust the man-hour. When the same specifications, the same When the substrate of one material is processed repeatedly, it is not necessary to change the setting frequently. However, when it is desired to continuously divide different types of substrates, the setting must be changed at this time, and thus the required working hours are required. .

Accordingly, it is an object of the present invention to provide a division method for stably dividing a substrate by forming a groove or a crack on a substrate by irradiating a laser and dividing the substrate by performing a fracture process along the formed groove or crack. And can reduce the bending moment (breaking pressure) required for the division.

Further, it is an object of the present invention to provide a method of dividing which does not need to take into consideration appropriate heating and cooling conditions which are set so as not to be affected by a compressive stress region formed inside the substrate, that is, even in a region where a compressive stress is generated. The processing is performed under heating or cooling conditions, or may be performed only by imparting a sufficiently small bending moment.

The method for dividing a brittle material substrate of the present invention, which has been developed to solve the above problems, comprises the steps of: relatively moving a beam spot formed by irradiation of a laser beam along a predetermined dividing line set on a brittle material substrate; The substrate is heated from the surface of the substrate at a temperature lower than the softening point, and then the cooling point formed by ejecting the refrigerant from the nozzle moves relative to the beam spot to cool the substrate, thereby forming a crack. And a breaking step of separating by applying a bending moment along the formed crack; in the method of dividing the brittle material substrate, in the step of forming a crack, heating conditions and/or cooling conditions are along a dividing line Periodically changing, whereby the maximum depth at which the crack is formed is within a depth limited by the region of the compressive stress inside the substrate, and the depth of the crack is changed along the predetermined dividing line direction by the heating condition or/and the cooling condition a periodic crack; in the breaking step, a bending moment is applied to the periodic crack from the back side of the substrate.

According to the invention, in the step of forming the crack, at least one of the heating condition or the cooling condition of the substrate is periodically changed along the planned dividing line, thereby imparting a temperature difference that periodically changes to the substrate. Thereby, the internal stress difference between the compressive stress caused by heating and the tensile stress caused by cooling periodically changes in the substrate. Therefore, the crack generated by the stress difference also periodically changes to form a "period crack". At this time, for the reason described above, a compressive stress region is generated inside the substrate (see FIG. 13), and the maximum depth of the periodic crack is limited by the compressive stress region (the maximum depth is about 1 to 40% of the thickness). On the other hand, if a bending moment is applied from the back side of the substrate along the predetermined dividing line in which the periodic crack is formed, the bending moment concentrates on any crack peak portion (stress concentration) on the periodic crack, even if the crack is formed. Shallow, it can also be broken only by giving a small bending moment.

According to the present invention, since the periodic crack is formed and the stress is concentrated in the crack peak portion of the periodic crack in the fracture treatment after the crack formation, the stress can be obtained only by imparting a small bending moment (breaking pressure). The concentration point is used as a starting point to easily perform the breaking process.

In the above invention, the heating condition or the cooling condition in the step of forming the crack may also be (1) the amount of refrigerant injection forming the cooling point, (2) the scanning speed of the beam spot, and (3) the arrival of the beam spot to the cooling point. The time until (4) the intensity of the laser beam forming the beam spot, (5) the pulse interval of the laser beam forming the beam spot, and (6) the shape of the beam spot Less than one periodically changes.

These parameters are parameters which can change the degree of heating and the degree of cooling of the substrate to make the temperature gradient in the thickness direction of the substrate poor. Therefore, by changing any parameter or several parameters periodically, it is possible to change periodically. Form periodic cracks.

In the above invention, the wavelength of the periodic crack may be 10 mm to 200 mm, and the difference between the maximum depth and the minimum depth of the periodic crack is 1% to 5% of the thickness of the substrate.

Accordingly, regardless of whether the wavelength of the periodic crack is too short (less than 10 mm) or too long (more than 200 mm), the bending moment (breaking pressure) is hard to concentrate at the time of the fracture, and therefore, by setting the appropriate wavelength (10 mm to 200 mm), It is easy to apply the bending moment in a concentrated manner. Further, by making the depth difference between the maximum depth and the minimum depth of the periodic cracks 1% to 5% of the thickness of the substrate, the peak portion of the crack can be remarkably exhibited, and thus the bending moment can be easily applied intensively. In particular, when the brittle material substrate is a glass substrate, if a periodic crack in the numerical range is formed, the division can be easily performed.

Further, in order to solve the problem of the present invention, another method for dividing a brittle material substrate according to the present invention includes the steps of: dividing a beam spot formed by irradiation of a laser beam along a substrate set on a brittle material substrate. a step of relatively moving the predetermined line to heat the substrate at a temperature above the melting temperature to form a groove; and a step of separating by applying a bending moment along the formed groove; the method of dividing the substrate of the brittle material In the step of forming the groove, the depth of the groove is formed along the line dividing the division by periodically changing the heating condition along the dividing line. A periodic groove that changes in a cycle of the above heating conditions; in the breaking step, a bending moment is applied to the periodic groove from the back side of the substrate.

According to the invention, in the step of forming the groove, the heating condition of the substrate is periodically changed along the dividing line, thereby forming a "period groove" in which the depth periodically changes. Then, if a bending moment is applied from the back side of the substrate along the predetermined dividing line in which the periodic groove is formed, the bending moment is concentrated on any depth peak portion (stress concentration) of the periodic groove, even if the groove is formed shallow overall. It can be broken only by imparting a small bending moment. That is, since the entire groove is formed shallow, the contamination caused by the evapotranspiration on the surface of the substrate is small, and it can be surely broken by a small bending moment.

In the above invention, in the step of forming the groove, when the periodic groove is formed and the periodic crack is formed at the bottom of the periodic groove, the bending moment can be applied to the periodic groove and the periodic crack.

According to this, when a periodic crack is formed at the bottom of the periodic groove, the bending moment is concentratedly applied to the peak of the periodic crack, and therefore, a small bending moment is similarly applied to break the same. Since the entire groove is formed shallow, the surface of the substrate is less polluted.

In the above two inventions, the heating conditions at which the crack is formed may also be (1) the scanning speed of the laser beam, (2) the irradiation intensity of the laser beam, (3) the depth of the focus of the laser beam, and (4) At least any one of the pulse intervals of the laser beam periodically changes.

These parameters all have an influence on the amount of melting of the substrate (or the depth of the molten portion), and therefore, by cyclically changing any parameter or several parameters The cycle can be formed.

In the above invention, the wavelength of the periodic groove may be changed to a wavelength of 1 mm to 10 mm, and the difference between the maximum depth of the periodic groove and the minimum depth may be 1% to 5% of the thickness of the substrate.

Accordingly, by setting the wavelength of the change in the period of the periodic groove to an appropriate wavelength (1 mm to 10 mm), it is easy to apply the bending moment in a concentrated manner. Further, by making the depth difference between the maximum depth and the minimum depth of the periodic groove 1% to 5% of the thickness of the substrate, the peak portion of the groove is remarkably expressed, and the bending moment is easily applied collectively. In particular, when the brittle material substrate is a sapphire substrate, periodic cracks in the numerical range can be easily divided.

Embodiments of the present invention will be described with reference to the drawings. Here, the case where a single glass substrate is divided is described as an example. However, the present invention can be applied to a bonded substrate in which a plurality of substrates are bonded to a brittle material substrate other than glass or a flat panel display substrate.

(First embodiment)

As a first embodiment of the present invention, a method of dividing by laser scribing processing will be described. In the dividing method, a laser scribing device that forms a periodic crack along a predetermined dividing line and a breaking device that applies a bending moment (breaking pressure) along the formed periodic crack are used.

First, the laser scribing device will be described. Fig. 1 is a configuration diagram of a laser scribing apparatus used in a method of dividing a brittle substrate according to an embodiment of the present invention, and Fig. 2 is a block diagram of a control system.

The overall configuration of the laser scribing apparatus will be described with reference to Fig. 1. The laser scribing device LS is provided with a slide table 2 that reciprocates in a front-rear direction (hereinafter referred to as a Y direction) of the paper surface along a pair of guide rails 3 and 4 arranged in parallel on the horizontal gantry 1. It is configured such that a lead screw 5 is disposed between the two guide rails 3 and 4 along the front-rear direction, and the bracket 6 fixed to the slide table 2 is screwed to the lead screw 5, and the motor is used. Not shown), the lead screw 5 is rotated, whereby the slide table 2 moves in the Y direction along the guide rails 3, 4, and reciprocates according to the steering of the motor.

On the slide table 2, a horizontal pedestal 7 that can reciprocate along the guide rail 8 in the left-right direction of FIG. 1 (hereinafter referred to as the X direction) is disposed. On the bracket 10 fixed to the pedestal 7, a lead screw 10a that is rotated by the driving of the motor 9 is screwed through, and the pedestal 7 moves in the X direction along the guide rail 8 due to the rotation of the lead screw 10a, according to the steering of the motor And move back and forth.

The turret 7 is provided with a rotary table 12 that is rotated by the rotation mechanism 11, and a glass substrate G which is a brittle material substrate to be cut is placed on the surface of the rotary table 12 in a horizontal state, and Fix it as needed. The rotation mechanism 11 is formed such that the rotary table 12 is rotated as an axis of rotation perpendicular to the mounting surface, and is rotatable to an arbitrary rotation angle with respect to the reference position. The glass substrate G is fixed to the turntable 12 by, for example, a suction cup.

Above the rotating table 12, a laser 13 and an optical system adjusting mechanism 14 are fixed to the mounting frame 15, and the laser 13 oscillates a laser beam having a circular cross section at a predetermined power (irradiation intensity) and a pulse interval. The optical system adjusting mechanism 14 generates light in a sectional shape of the above-mentioned laser beam The beam is deformed to form an elliptical beam spot HS on the glass substrate G (Fig. 2).

In order to heat the substrate at a temperature less than the melting temperature of the substrate without melting the substrate, the laser 13 uses a laser having a long wavelength, such as a CO ₂ laser. FIG. 3 is a view showing the internal configuration of the optical system adjusting mechanism 14. A plano-convex lens 14a is attached to the upper side of the optical path L of the laser beam, and a lenticular lens 14b is attached to the lower side, and the position can be adjusted in the up-down direction (Z direction) by a motor (not shown). The mode is supported by the lens position adjusting mechanisms 14c, 14d. By adjusting the position of the plano-convex lens 14a, the length of the short axis when forming the beam spot of the elliptical shape is mainly adjusted (adjustment in the width direction), and the length of the long axis is adjusted by adjusting the position of the lenticular lens 14b.

A cooling nozzle 16 is attached to the mounting frame 15 and the optical system adjusting mechanism 14. The cooling nozzle 16 sprays a cooling medium such as cooling water, helium or carbon dioxide onto the glass substrate G to form a cooling point CS on the surface of the glass substrate G (FIG. 2). The refrigerant is sent from the refrigerant supply source (not shown) to the nozzle 16 via the flow rate adjustment valve 16a. The start of the injection and the stop of the injection are controlled by the opening and closing of the flow rate adjusting valve 16a, and the amount of injection of the refrigerant is controlled by adjusting the opening degree.

The nozzle 16 is provided with a nozzle position adjusting mechanism 16b that adjusts the position of the nozzle 16 in the X direction by being driven by a motor (not shown). The nozzle position adjusting mechanism 16b adjusts the distance between the cooling point CS and the beam spot HS, thereby adjusting the time from the heating to the cooling.

Further, the cutter wheel 18 is attached to the mounting frame 15 via the vertical adjustment mechanism 17. The cutter wheel 18 is made of sintered diamond or super hard alloy, and has a V-shaped ridge portion having a vertex as a tip on the outer peripheral surface, and the cutter wheel 18 is provided. The pressure contact force to the glass substrate G can be adjusted by the up-and-down adjustment mechanism 17. When the initial crack TR is to be formed at the edge (or other than the edge) of the glass substrate G, the cutter wheel 18 is temporarily lowered.

Further, a camera 20 is mounted on the mounting frame 15, and the camera 20 captures an alignment mark imprinted on the glass substrate G. The position of the alignment mark on the glass substrate G is previously stored in the control system, and the positioning of the glass substrate can be performed by the alignment mark (laser irradiation and refrigerant ejection at a specific position of the glass substrate).

Then, the control system is explained. As shown in FIG. 2, the control system of the laser scribing device LS is a control unit 50 including a CPU and controlling the entire device, an input unit 51 including a keyboard and a mouse, and performing various input operations, and including a liquid crystal panel and displaying a display unit 52 that controls an input screen of information or parameters, a storage unit 53 that stores a control program or parameters for control, and a drive unit (a table drive unit 61 that is driven under the control of the control unit 50, and a laser drive) The unit 62, the optical system drive unit 63, the refrigerant drive unit 64, the nozzle drive unit 65, the camera drive unit 66, and the cutter drive unit 67) are configured.

The storage unit 53 stores in advance the amount of refrigerant injection, the relative scanning speed of the beam spot and the cooling point with respect to the substrate, the distance between the beam spot and the cooling point, the laser irradiation intensity (laser output), the laser pulse interval, And the shape of the beam spot as a control parameter for use as a heating condition or a cooling condition. These control parameters can be appropriately set by the input screen displayed on the input unit 51 and the display unit 52.

Next, the control unit 50 is based on the above control stored in the storage unit 53. Parameters, which generate control signals to form periodic cracks. That is, control is performed by generating a control signal that periodically changes at least one of control parameters as heating conditions or cooling conditions, so that the substrate G is periodically cycled while scanning the laser beam along the dividing line. Heating or cooling of sexual changes. The specific control will be described later. The generated control signals are transmitted to the corresponding drive units to perform control operations.

Hereinafter, each drive unit will be described. The stage drive unit 61 drives a motor (motor 9 or the like) for positioning the slide table 2, the pedestal 7, and the rotary table 12. When a periodic crack is formed, the pedestal 7 is scanned in the X direction in accordance with the scanning speed set in the storage unit 53.

The laser driving unit 62 irradiates the laser beam from the laser beam 13. When a periodic crack is formed, the laser beam is irradiated according to the laser irradiation intensity and the laser pulse interval set in the storage portion 53.

The optical system drive unit 63 drives the lens position adjustment mechanisms 14c and 14d of the optical system adjustment mechanism 14. When a periodic crack is formed, a beam spot that is deformed according to the shape (long axis length, short axis length) of the beam spot set in the storage portion 53 is irradiated.

The refrigerant drive unit 64 drives the flow rate adjustment valve 16a that controls the amount of refrigerant injection. When a periodic crack is formed, the refrigerant is injected in accordance with the amount of refrigerant injection set in the storage unit 53.

The nozzle drive unit 65 drives the nozzle position adjustment mechanism 16b for adjusting the position of the cooling nozzle 16. When the periodic crack is formed, the position of the nozzle 16 is adjusted in accordance with the distance between the points set in the storage portion 53. Furthermore, depending on the distance between the points and the scanning speed, the beam point HS is determined to pass through to the cold. However, the time until the CS passes (called the heating/cooling time). The longer the heating/cooling time, the deeper the crack.

In addition to the above-described respective drive units, the camera drive unit 66 drives the camera 20 to take an alignment mark. The positioning of the substrate G is performed in accordance with the alignment marks taken.

Further, the cutter drive unit 67 drives the cutter wheel 18. Thereby, an initial crack is formed on the substrate G.

Then, the control signal when the periodic crack is formed is specifically described. In order to form a periodic crack, a control signal for periodically changing at least one of the control parameters stored in the storage unit 53 is generated. Hereinafter, the control parameters will be described one by one.

(1) Refrigerant injection amount

In the case where the refrigerant injection amount is periodically changed and the other control parameters are maintained at a fixed control signal, the depth of the crack in the portion where the amount of refrigerant injection is small becomes shallow, and the depth of the crack in the portion where the amount of refrigerant injection is large becomes deep. . That is, in the portion where the refrigerant is strongly cooled and strongly cooled, the temperature gradient (temperature difference) in the thickness direction of the substrate becomes large, and the stress difference in the portion becomes large and the crack extends deep.

(2) Scanning speed

In the case where the scanning speed of the beam spot (and the cooling point) is periodically changed on the substrate while the other control parameters are maintained as a fixed control signal, the depth of the crack in the faster scanning portion becomes shallower, and the scanning speed is slower. The depth of the crack in the part becomes deeper. That is, the portion of the slower scanning speed is heated and the heat is increased, and the stress difference in the portion is increased and the crack is extended. Got deeper.

(3) Distance between beam point and cooling point (distance between points)

In the case of a control signal that changes the period between points and maintains other control parameters to be fixed (the scanning speed of the beam spot is also fixed), the distance between the points is shortened and the heating/cooling time is shortened (after the beam point HS passes to the cooling) The depth of the crack in the portion where the point CS passes is shallow, and the distance between the points is extended to extend the depth of the crack in the portion between the heating and cooling periods. That is, the region of the compressive stress (i.e., the region where the crack extension is restricted) when the portion is extended by the distance between the points is deepened, so that the crack extends deeper.

(4) Laser irradiation intensity (power)

In the case of a control signal that causes the laser irradiation intensity (power) to change periodically while maintaining other control parameters to be fixed, the depth of the crack in the weaker portion of the laser beam is shallower, and the intensity of the laser beam is increased. The depth of the crack in the stronger part becomes deeper. That is, in the portion where the irradiation intensity is strong, the amount of heat supplied is increased and intensely heated, and the stress difference in the portion becomes large and the crack extends deep.

(5) Laser pulse interval

When the period of the pulse interval of the laser is changed and the other control parameters are maintained to be fixed, the depth of the crack in the portion where the laser pulse is longer is shallow, and the crack in the portion where the pulse interval of the laser is shorter is small. The depth becomes deeper. That is, the heat supply in the portion where the pulse interval is shorter is strongly heated, and the stress difference in the portion becomes large and the crack extends deep.

(6) Beam spot shape

In the laser scribing process, the long-axis direction of the beam spot such as an elliptical shape is aligned with the planned dividing line (predetermined line) to scan the beam spot. When the length of the long axis at this time is changed periodically and other control parameters are fixed, there is a tendency that heat per unit area becomes large in the portion where the length of the long axis is short, and the depth of the crack becomes deep, and the length of the long axis In the longer part, the amount of heat per unit area becomes smaller and the depth of the crack becomes shallower.

Further, regarding the control parameters of the above (1) to (6), a plurality of control parameters may be simultaneously changed in a periodic manner. For example, the amount of refrigerant injection and the intensity of laser irradiation can be simultaneously changed to increase the temperature difference generated in the substrate.

Then, the scribing action will be described. Compared with the conventional scribing operation, the difference in the use of the above-described laser scribing device LS is that the driving unit is operated by a part of the control signals whose control parameters are periodically changed, and the rest are the same.

That is, the initial crack TR is formed by the cutter wheel 18 at the end of the dividing line, and then the beam spot HS and the cooling point CS are scanned along the dividing line. At this time, each of the drive units is controlled by a part of the control signals whose control parameters are periodically changed. Thereby, a periodic crack is formed on the substrate G.

4 is a schematic view showing a periodic crack formed on the substrate G when the laser beam scribing is performed while periodically changing the control parameters, and FIG. 4(a) is a perspective view of the substrate G, and FIG. 4(b) is A-A'. In the cross-sectional view, Fig. 4(c) is a B-B' cross-sectional view, and Fig. 4(d) is a C-C' cross-sectional view.

The beam spot HS and the cooling point CS are scanned linearly from the initial crack TR, whereby the crack Cr is formed as shown in FIG. 4(a), and a linear scribe line SL is formed on the surface of the substrate.

At this time, as shown in FIGS. 4(a) and 4(b), it extends in the thickness direction. The tip portion of the crack Cr forms a waveform W having the same period as the period in which the control parameter changes, and a periodic crack is formed.

The wavelength of the periodic crack formed is varied corresponding to the period of variation (i.e., wavelength) of the control parameter. When the wavelength of the periodic crack is set to an appropriate wavelength, when a bending moment is applied to the substrate G by using a breaking device described later, the bending moment (breaking pressure) is concentrated on the peak of the periodic crack (mountain portion), so even the applied bending moment Smaller can also be easily segmented.

In the case of a substrate such as glass, it can be judged from experience that the bending moment (breaking pressure) tends to concentrate on the peak of the periodic crack (mountain portion) and the wavelength of the crack is 10 mm to 200 mm. Therefore, the period of the control parameter is adjusted in consideration of the relationship with the scanning speed so as to be within the wavelength range.

Moreover, if the depth difference between the maximum depth and the minimum depth of the periodic crack is 1% to 5% of the thickness of the substrate, the mountain of the periodic crack and the peak portion of the valley are remarkably expressed, so that the breaking device is easy to apply the bending moment intensively. .

Although the depth difference between the maximum depth and the minimum depth of the periodic crack depends on the thickness of the substrate G, for example, if the thickness of the substrate is about 0.5 mm to 1 mm, the depth difference may be in the range of 5 μm to 50 μm. .

Further, as shown in Figs. 4(c) and 4(d), the tip (the deepest portion) of the formed periodic crack is stopped due to the influence of the compressive stress region generated in the substrate when the crack is formed, and as a result, the periodic crack The depth is usually 10% to 40% of the thickness of the board, and does not extend further.

Next, the breaking device will be described. Fig. 5 (a) is a schematic configuration diagram of a breaking device used in a method of dividing a brittle substrate according to an embodiment of the present invention. The same components as those in Fig. 1 are denoted by the same reference numerals, whereby Some explanations are omitted.

Here, for convenience of explanation, the space coordinates (x, y, z) are used, and the reference plane parallel to the installation ground of the breaking device 10 is set to (x, y, z ₀ ), and the direction perpendicular to the ground is set. For the z-axis, the dividing direction (breaking direction) of the substrate G is set to the y-axis. The breaking device BM has a slide table 23a slidable in the -x-axis direction, and a tilting table 23b which is tiltable about the rotation axis parallel to the y-axis and slidable in the +x-axis direction.

Fig. 5b is a perspective view showing the left unit BM (A) and the right unit BM (B) of the breaking device BM in a separated state. When the breaking device BM is integrally mounted on the gantry 1 of FIG. 5a, the left side unit BM (A) refers to the mechanism portion disposed on the left side (-x-axis direction) of the scribe line SL on the substrate G shown in FIG. 5a, and the right side. The unit BM (B) is a mechanism portion provided on the right side (+x-axis direction) of the scribe line SL of the substrate G.

Further, in order to mount and hold the substrate G to be cut, the first product stage 24a is fixed to the slide table 23a, and the second product stage 24b is fixed to the inclined table 23b. Further, the first product holding unit 25a is attached to the upper portion of the first product table 24a, and the second product holding unit 25b is attached to the upper portion of the second product table 24b. The scribe line SL of the substrate G is parallel to the y-axis, and the region on the -x-axis side (left side) of the substrate is referred to as the left portion GL of the substrate, and the region on the +x-axis side (right side) is referred to as a substrate. Right GR. The first product pinching unit 25a strongly presses the right end portion of the left side portion GL of the substrate to fix the substrate, and the second product pinching unit 25b strongly presses the left end portion of the right portion GR of the substrate to fix the substrate.

A slide mechanism 26 is provided in the left unit BM (A). Sliding mechanism 26 The slider 23a is biased in the -x-axis direction, and an elastic member that imparts an elastic force, such as a cylinder, a spring, or the like, is provided. Further, the slide mechanism 26 is provided with a stopper for restricting the sliding range, a damper for limiting the sliding speed, and the like (not shown).

The right unit BM (B) is held by a pair of horizontal holding block upper portions 27a as a pillar and a pair of horizontal holding block lower portions 27b. The horizontal holding block lower portion 27b is fixed to the gantry 1, and the horizontal holding block upper portion 27a rotatably holds the inclined table 23b. A sliding unit (not shown) is disposed between the horizontal holding block upper portion 27a and the horizontal holding block lower portion 27b, and the horizontal holding block upper portion 27a is slidably adjustable in the x-axis direction. Further, the horizontal holding block upper portion 27a on the +y-axis side and the -y-axis side is provided with the tilting shaft 28, and the inclined table 23b, the second product stage 24b, and the second product holding unit 25b are rotatable by the tilting shaft 28 The shaft is held while being tilted. The tilting shaft 28 is provided with a bearing housing, for example, in the horizontal block upper portion 27a, and the tilting shaft 28 is held by a ball bearing that is pressed into the bearing housing. Here, the horizontal holding block upper portion 27a and the inclined shaft 28 are referred to as a tilt mechanism.

The first product clamping unit 25a fixes the left portion GL of the substrate, and concentrates the shear stress and the bending stress on the scribe line SL of the substrate. The first product clamping unit 25a is provided with a first clamping strip 29a that presses the vicinity of the scribe line SL of the substrate G. The tip end of the first nip 29a is located on the right side edge of the first product table 24a, and is slightly movable in the z-axis direction. Similarly, the second product pinching unit 25b fixes the right portion GR of the substrate, and concentrates the shear stress and the bending stress on the scribe line SL of the substrate. The second product clamping unit 25b is provided with a second clamping strip 29b that presses the vicinity of the scribe line SL of the substrate G. The top of the second clamp strip 29b The end is located at the left edge of the second product table 24b and can be slightly moved in the Z direction.

The method of holding the substrate G can be fixed to the product stage by vacuum adsorption or other methods. When the substrate is glass and a resin is formed on the surface thereof, it may be fixed by electrostatic adsorption.

Next, the tilting mechanism of the tilting table 23b will be described. As shown in Figs. 5a and 5b, the tilting shaft 28 of the block upper portion 27a is horizontally held so that the entire right side unit BM (B) except the horizontal holding block lower portion 27b can be rotated with the tilting axis 28 in Fig. 6a. Rotate in the CW direction or CCW direction. Fig. 6a is a cross-sectional view showing the main part of the breaking device showing the mounting position of the tilt shaft 28. The rotation control unit 30 is provided to rotate the tilting table 23b via the tilt mechanism. The rotation control unit 30 can rotate the tilting table 23b by a predetermined angle using a rotational force of a motor or a hydraulic cylinder, or can manually rotate the tilting table 23b via an arm or a link. Further, the tilting table 23b moves in the +x-axis direction while starting the rotation.

In the initial setting of the breaking device, the first product stage 24a and the second product stage 24b are positioned to maintain the same mounting surface with respect to one of the substrates G. The height of the tilting shaft 28 is adjusted such that the tilting shaft 28 is at a central position when viewed from the upper surface and the lower surface of the substrate G placed on the stage.

The thickness of the substrate G is set to 2d ₀ . The mounting surface of the first product stage 24a is (x, y, -d ₀ ), and the position of the tilt axis 28 is (0, y, -d ₀ to +d ₀ ). The position of the tilting shaft 28 can be adjusted according to the thickness and material of the substrate G. Further, when the distance between the right edge of the first product table 24a and the left edge of the second product table 24b is 2 g, it is preferable that the first clamp bar 29a presses the substrate G and the second clamp bar The interval between the pressing positions of 29b and the substrate G is the same as 2g. Further, it is preferable that the tilt axis 28 is parallel to the scribe line SL of the substrate G and is located within the thickness range of the substrate.

Fig. 6(b) is a partially enlarged cross-sectional view showing the breaking device centered on the scribe line SL. Here, the position after division of the substrate G is indicated by a solid line. The position (x, y, z) of the tilt axis 28 is set to (0, y, 0). On the right side of the divided substrate GR, the end point of the scribe line SL is set to PR. Further, the end point of the line in which the right side portion GR of the substrate and the left edge of the second product stage 24b are in contact with each other is set to PR'. Further, the PR before the division and the cutting of the substrate G is made to coincide with the PL (the end point of the scribe line SL of the divided left portion GL of the substrate).

As shown in FIG. 6(b), when the second product stage 24b is inclined by an angle θ in the CCW direction, the position of the point PR' moves from (0, y, 0) to (x ₂ , y, z ₂ ). Here, the coordinate values are as follows.

x ₁ =0 z ₁ =-d ₀ x ₂ =d ₀ Sin θ z ₂ =d ₀ (1-COS θ)-d ₀

When the portion of the point PR' (x ₂ , Y, z ₂ ) of the right portion GR of the substrate becomes a fixed point with respect to the second product stage 24b by the pressing force of the second nip 29b, the fixed point PR is The shearing force and the tensile force (bending moment) are applied to the fracture portion located at the point PR of the right portion GR of the substrate, and the substrate G is divided. When the substrate G is cut, the elastic force in the -x-axis direction acts on the left portion GL of the substrate by the sliding mechanism 26, and the tilting table 23b moves in the +x-axis direction while starting to rotate, and serves as a cutting surface of the left portion GL of the substrate. The right edge portion retreats in the -x-axis direction without coming into contact with the left edge portion of the right portion GR of the substrate. Therefore, the divided surface of the glass substrate is not damaged, and a smooth divided surface can be obtained.

The horizontal movement amount x ₂ -x ₁ at this time is calculated, and when θ = 3°, x ₂ -x ₁ is 0.039 mm.

The substrates GR and GL which are divided into right and left at the scribe line SL are used to release the first slats 29a and the second slats 29b from the substrate G, whereby the substrates GR and GL can be detached from the product stage. When one of the strip-shaped substrates in the x-axis direction is divided into a plurality of portions, the scribe lines SL are respectively provided at predetermined positions of the substrate G. Then, the substrate G is conveyed at a predetermined pitch in the x direction, and the product pinching units 25a and 25b are provided, and the tilting table 23b is sequentially inclined. By repeating this operation, a plurality of substrates can be fabricated from a single mother substrate.

When the second product stage is inclined, a bending moment (bending stress) is applied, and the cross section of the substrate is formed in a V shape centering on the position where the scribe line is formed. Further, when a bending moment is applied in a manner of forming a V-shape, the crack spreads from the lower surface of the substrate (the surface in contact with the product table), so the bending moment concentrates on the tip end portion of the crack closer to the lower surface side (the peak of the periodic crack) . At this time, at the bottom of the periodic crack, the tip of the crack is only slightly extended at the tip of the front and rear portions of the paper, so a large bending moment is required at the start of the division. On the other hand, at the peak of the periodic crack, the paper surface extends deeper at the tip end of the front and rear cracks, so that a large bending moment is not required when starting the division. Therefore, the peak of the periodic crack can be easily divided as a starting point.

(Second embodiment)

Next, a division method using a laser ablation processing as a second embodiment of the present invention will be described. Here, a case where a single sapphire substrate is divided will be described as an example. In the dividing method, the use is formed along a dividing line A laser ablation device for a periodic groove, and a breaking device for applying a bending moment (breaking pressure) along the formed periodic groove. Here, the breaking device is the same as the breaking device described in the first embodiment, and thus the description thereof is omitted.

The laser ablation device will be described. Fig. 7 is a view showing a configuration of a laser ablation apparatus used in a method of dividing a brittle substrate according to an embodiment of the present invention, and Fig. 8 is a block diagram of a control system. Incidentally, the same components as those of the laser scribing device LS of FIGS. 1 and 2 are denoted by the same reference numerals, and the description thereof will be omitted. In the laser ablation device LA, a short-wavelength laser which is easier to melt the substrate than the laser scribing device is used. Moreover, forced cooling after heating is not necessary, so no cooling mechanism is used.

Next, the overall configuration of the laser ablation device LA will be described. The slide table 2, the pedestal 7, and the rotary table 12 for moving the position of the sapphire substrate G in the XY direction and the rotational direction are the same as those in the laser scribing device LS.

Above the rotating table 12, a laser 35 and an optical system adjusting mechanism 36 are fixed to the mounting frame 15, and the laser 35 oscillates a laser beam (original beam) with a predetermined output and a pulse interval. The optical system adjusting mechanism 36 is provided. The original beam is condensed to form a beam spot HS (Fig. 8) on or near the surface of the glass substrate G.

In order to heat the substrate material at a temperature above the melting temperature, the laser 35 uses a laser having a shorter wavelength, such as a UV laser.

Fig. 9 is a view showing the internal configuration of the optical system adjusting mechanism 36. A convex lens 36a is attached along the optical path L of the laser beam, and the position can be adjusted by a lens position adjusting mechanism 36b driven by a motor (not shown). The shape of the beam spot HS can be set by changing the focus position of the convex lens 36a. And adjust the depth position when the substrate is melted.

Then, the control system is explained. As shown in FIG. 8, the control system of the laser ablation device LA is composed of a control unit 50, an input unit 51, a display unit 52, a storage unit 55, and each drive unit (a drive unit that is driven under the control of the control unit 50). 61. The laser driving unit 62, the camera driving unit 66, and the optical system driving unit 63) are configured.

In the storage unit 55, the scanning speed of the substrate, the depth of focus of the laser beam, the laser irradiation intensity (laser power), and the laser pulse interval are stored in advance as control parameters. These control parameters can be appropriately set by the input screen displayed on the input unit 51 and the display unit 52.

Further, the control unit 50 generates a control signal for forming a periodic groove based on the control parameter stored in the storage unit 55. That is, by generating a control signal that periodically changes at least one of the control parameters, the substrate G is caused to have a molten state that periodically changes along the planned dividing line. The specific control will be described later. The generated control signals are transmitted to the corresponding drive units to perform control operations.

Then, each drive unit will be described. The stage drive unit 61 drives a motor (motor 9 or the like) for positioning the slide table 2, the pedestal 7, and the rotary table 12. When the periodic groove is formed, the pedestal 7 is scanned in the X direction in accordance with the scanning speed set in the storage unit 55.

The laser driving unit 62 irradiates the laser beam from the laser light 35. When the periodic groove is formed, the laser beam is irradiated according to the laser irradiation intensity (output) and the laser pulse interval set in the storage portion 55.

The lens position of the optical system adjustment mechanism 36 to the optical system adjustment mechanism 36 The adjustment mechanism 36b is driven. When the periodic groove is formed, the focus position of the laser beam is adjusted in accordance with the depth of focus set in the storage portion 55.

Then, the control signal when forming the periodic slot is specifically described. In order to form a periodic slot, a control signal that periodically changes at least one of the above control parameters is generated. Hereinafter, the control parameters will be described one by one.

(1) Scanning speed

In the case where the scanning speed is periodically changed while the other conditions are maintained as a fixed control signal, the depth of the groove in the portion where the scanning speed is faster becomes shallower, and the depth of the groove in the portion where the scanning speed is slower becomes deeper. That is, the portion of the slower scanning portion is heated to be strongly melted, and the groove of the portion is formed deeper.

(2) Depth of focus

In the case of a control signal that causes the focus depth of the laser beam to change periodically while maintaining other conditions to be fixed (the scanning speed is also fixed), the depth of the groove is shallower in the portion of the substrate surface or the shallower position, and the focus is The depth of the groove becomes deeper in the portion where the depth is deeper. That is, the deeper portion of the depth of focus is strongly melted deeper, so that the groove extends deeper.

(3) Laser irradiation intensity

In the case of a control signal that causes the laser irradiation intensity to change periodically while maintaining other conditions to be fixed, the depth of the groove in the weaker portion of the laser beam becomes shallower, and the groove depth becomes deeper in the portion where the irradiation intensity is stronger. . That is, the portion where the irradiation intensity is strong is increased in heat and is strongly melted, and the groove of the portion is formed deep.

(4) Laser pulse interval

When the period of the pulse interval of the laser is changed and other conditions are maintained to be fixed, the groove depth becomes shallower in the portion where the laser pulse is longer, and the groove depth becomes deeper in the portion where the pulse interval is shorter. That is, the heat supply in the portion where the pulse interval is shorter is increased and is strongly melted, and the groove of the portion is formed deep.

Further, regarding the control parameters of the above (1) to (4), a plurality of control parameters may be simultaneously changed in a periodic manner. For example, the scanning speed can be changed simultaneously with the depth of focus.

Then, the erosion action is explained. Compared with the previous ablation operation, the difference in the use of the above-described laser ablation device LA is that the drive unit is operated by a part of the control signal whose control parameters are periodically changed, and the rest are the same.

That is, the beam spot HS is scanned along the division planned line, and the substrate G is melted. At this time, each of the driving sections is controlled by a part of the control signals whose control parameters are periodically changed. Thereby, a periodic groove is formed in the substrate G.

Fig. 10 is a schematic view showing a periodic groove formed on the substrate G when the laser ablation processing is performed while periodically changing the control parameters, and Fig. 10(a) is a perspective view of the substrate G, and Fig. 10(b) is A-A. 'Sectional view, Fig. 10(c) is a B-B' cross-sectional view, and Fig. 10(d) is a C-C' cross-sectional view.

By scanning the beam spot HS in a straight line, the groove Gr is formed as shown in Fig. 10 (a), and a linear line AL is formed on the surface of the substrate.

At this time, as shown in FIGS. 10(a) and 10(b), the tip end portion of the groove Gr extending in the thickness direction is a waveform W having the same period as the period in which the control parameter fluctuates, and a periodic groove is formed.

The wavelength of the formed periodic groove varies according to the period of variation (i.e., wavelength) of the control parameter. By setting the wavelength of the periodic groove to an appropriate wavelength, when a bending moment is applied to the substrate G using the breaking device BM, a bending moment (breaking pressure) is collectively applied to the peak (mountain portion) of the periodic groove, and only by It is easy and stable to divide by applying a small bending moment.

In the case of a substrate such as sapphire, it is judged empirically that the wavelength of the periodic groove in which the bending moment (breaking pressure) can be collectively applied is 1 mm to 10 mm. Therefore, the period of the control parameter is adjusted in consideration of the relationship with the scanning speed so as to be in the wavelength range.

Moreover, if the depth difference between the maximum depth and the minimum depth of the periodic groove is 1% to 5% of the thickness of the substrate, the peak of the periodic groove and the peak portion of the valley can be remarkably expressed, so that the breaking device can easily apply the bending moment intensively. .

Further, if the processing time of the laser ablation is prolonged, the period groove formed may be deepened. However, the processing time is shortened as much as possible, and the breaking operation is performed in a state where the period groove is shallow. Even if the depth of the periodic groove is shallow, the bending moment can be applied to the peak portion of the periodic groove in a concentrated manner, and the bending can be performed with a small bending moment, and the contamination on the surface of the substrate in the ablation processing can also be reduced.

Further, the case where the groove Gr is formed by the above-described laser ablation processing has been described. However, depending on the material of the substrate material or the heating conditions, there are cases where, as shown in FIG. 11, not only the groove Gr but also the groove is formed. A crack Cr is formed at the bottom of the groove Gr, and the waveform W is formed by a periodic groove and a periodic crack.

This situation is also related to the case where the periodic groove is formed as illustrated in FIG. Similarly, if the fracture operation is performed in the state of the shallowest periodic groove and the periodic crack, the division can be performed with a small bending moment, and the contamination of the surface of the substrate generated in the ablation process can be reduced.

[Examples]

Next, a specific example of an embodiment of the present invention will be described.

(Example 1) Changing the amount of refrigerant injection to form a periodic crack

On the alkali-free glass substrate (length 300 mm × width 300 mm × thickness 0.7 mm) on which the initial crack TR was formed, a CO ₂ laser (output of 120 W) was scanned to form a scribe line, and at this time, the amount of refrigerant injection was changed to form a periodic crack. . The scanning speed of the beam spot and the cooling point was set to 150 mm/s, and the fluctuation period (switching interval) of the refrigerant injection amount was set to 1 second, and the amount of cooling water was sequentially switched at 0.8 cc/min, 1 cc/min, and 0.8 cc/min. The setting. The results are shown in Table 1.

If other conditions are set to be fixed, cracks at a position where the amount of cooling water per unit time is large (150 mm from the end portion) is formed deep. The penetration depth varies from 13 μm to 15 μm, which is 1.8% to 2.1% of the substrate thickness (0.7 mm).

(Embodiment 2) Changing the scanning speed to form a periodic crack

On the alkali-free glass substrate (length 300 mm × width 300 mm × thickness 0.7 mm) on which the initial crack TR was formed, a CO ₂ laser (output 150 w) was scanned to form a scribe line, at which time the scanning speed was changed to form a periodic crack.

The scanning speed of the laser beam and the cooling point is changed at 220 mm/s and 300 mm/s. The results are shown in Table 2.

If the scanning speed is changed by fixing other conditions, a deep crack is formed at a position where the scanning speed is slow.

(Example 3) Changing the laser irradiation intensity (output) to form a periodic crack

On the alkali-free glass substrate (length 800 mm × width 300 mm × thickness 0.7 mm) on which the initial crack TR was formed, a scribe line was formed using a CO ₂ laser, and at this time, the irradiation intensity was changed to form a periodic crack.

The scanning speed of the laser beam and the cooling point is fixed to 220 mm/s, so that the laser irradiation intensity (output) is changed by two powers of 150 W and 110 W. The results are shown in Table 3.

If other conditions are fixed, a deep crack is formed at a position where the irradiation intensity (output) is large.

[table 3]

(Embodiment 4) Changing the shape of the beam to form a periodic crack

On the alkali-free glass substrate (length 300 mm × width 300 mm × thickness 0.7 mm) on which the initial crack TR was formed, a scribe line was formed using a CO ₂ laser (output of 150 W), at which time the long axis of the beam point of the elliptical shape was changed. And the length of the short axis forms a periodic crack.

The scanning speed of the laser beam and the cooling point was fixed to 220 mm/s, and the long axis and the short axis were changed in two shapes of (40 mm × 1.5 mm) and (27 mm × 1.9 mm). The results are shown in Table 4.

If other conditions are fixed, a shallow crack is formed at a position where the long axis of the beam spot is long.

The present invention can be used in a method of irradiating a laser beam to a substrate such as a glass substrate.

12‧‧‧Rotating table

13‧‧ ‧ laser (CO ₂ laser)

14‧‧‧Optical system adjustment mechanism

16‧‧‧Cooling nozzle

16a‧‧‧Flow adjustment valve

16b‧‧‧Nozzle position adjustment mechanism

23a, 23b‧‧‧ slide table

25a, 25b‧‧‧ product clamping unit

35‧‧‧Laser (UV laser)

36‧‧‧Optical system adjustment mechanism

50‧‧‧Control Department

53, 55‧‧‧ Storage Department

CS‧‧‧cooling point

HS‧‧‧ beam spot

SL‧‧‧Dash (crack)

AL‧‧‧ditch (slot)

W‧‧‧Period crack or periodic groove waveform

Cr‧‧‧ crack

Gr‧‧‧ slot

LS‧‧•ray marking device

BM‧‧‧ breaking device

LA‧‧‧Laser ablation device

Fig. 1 is a view showing the configuration of a laser scribing apparatus used in a method of dividing a brittle substrate according to an embodiment of the present invention.

Fig. 2 is a block diagram showing the configuration of a control system of the laser scribing device of Fig. 1.

Fig. 3 is a view showing the internal configuration of an optical system adjusting mechanism of the laser scribing device of Fig. 1.

Fig. 4 is a view showing a periodic crack formed on a substrate when laser scribing is performed.

Fig. 5a is a schematic configuration diagram of a breaking device used in a method of dividing a brittle substrate according to an embodiment of the present invention.

Fig. 5b is a perspective view showing a separated state of the left unit (A) and the right unit (B) of the breaking device of Fig. 5a.

Fig. 6 is a schematic view for explaining a fracture process of a glass substrate on which a periodic crack is formed.

Fig. 7 is a view showing the configuration of a laser ablation apparatus used in a method of dividing a brittle substrate according to another embodiment of the present invention.

Fig. 8 is a block diagram showing the configuration of a control system of the laser ablation apparatus of Fig. 7.

Fig. 9 is a view showing the internal configuration of an optical system adjusting mechanism of the laser ablation device of Fig. 7.

Fig. 10 is a schematic view showing a periodic groove formed on a substrate when laser ablation processing has been performed.

Fig. 11 is a view showing a periodic groove and a periodic crack formed on a substrate when laser ablation processing has been performed.

Fig. 12 is a schematic cross-sectional view showing an example of a groove or a crack formed in a substrate by laser irradiation.

Figure 13 is a schematic cross-sectional view showing the thermal strain distribution generated in the substrate when the beam spot is scanned and then cooled.

Cr‧‧‧ crack

G‧‧‧glass substrate

SL‧‧‧Dash (crack)

TR‧‧‧ initial crack

W‧‧‧Period crack or periodic groove waveform

Claims (8)

A method for dividing a brittle material substrate, comprising: relatively moving a beam spot formed by irradiation of a laser beam along a dividing line set on a brittle material substrate, and from a substrate surface side at a temperature lower than a softening point The substrate is heated, and then the cooling point formed by ejecting the refrigerant from the nozzle is relatively moved in such a manner as to follow the beam spot to cool the substrate, thereby forming a crack; and, by forming a crack along the a step of breaking by applying a bending moment on the back side of the substrate; characterized in that in the step of forming a crack, the maximum depth of the crack is formed by periodically changing the heating condition and/or the cooling condition along the dividing line a crack within a depth limited by a region of compressive stress inside the substrate, and a depth at which the depth of the crack changes along a predetermined line of the heating condition or/and a period of the cooling condition; a heating condition of the step of forming the periodic crack or The cooling condition is such that at least one of the following parameters (1) to (6) periodically changes in the following manner. (1) The amount of refrigerant injected to form the cooling point is changed, the shallow crack is to reduce the amount of injection, the deep crack is to increase the injection amount; (2) the scanning speed of the beam point is changed, the shallow crack is increasing the scanning speed, and the deep crack is decreasing. Slow scanning speed; (3) time change after the beam point passes until the cooling point arrives, shallow cracks shorten the time, deep cracks increase the time; (4) change the irradiation intensity of the laser beam forming the beam spot, shallow crack The mark weakens the intensity of the illumination, and the deep crack enhances the intensity of the illumination; (5) changes the pulse interval of the laser beam forming the beam spot, the shallow crack increases the pulse interval, the deep crack shortens the pulse interval; and (6) makes the beam spot The shape has a long axis shape, and the long axis direction thereof changes in the direction along the predetermined line of the scribe line, and the shape of the long axis direction changes, the shallow crack increases the length of the major axis, and the deep crack shortens the length of the major axis. The method for dividing a brittle material substrate according to claim 1, wherein the periodic crack has a wavelength of 10 mm to 200 mm, and a depth difference between the maximum depth and the minimum depth of the periodic crack is 1% to 5% of the thickness of the substrate. The method for dividing a brittle material substrate according to claim 1, wherein the brittle material substrate is a glass substrate. A method for dividing a brittle material substrate, comprising: relatively moving a beam spot formed by irradiation of a laser beam along a dividing line set on a brittle material substrate, and heating the substrate at a temperature above a melting temperature to a step of forming a groove; and a step of separating the separation by applying a bending moment from the back side of the substrate along the formed groove; characterized in that in the step of forming the groove, the heating condition is predetermined along the division The line is periodically changed to form a periodic groove whose depth of the groove changes along the predetermined dividing line direction by the period of the heating condition; the heating condition of the step of forming the periodic groove is to make the following (1) to (3) At least one of the parameters periodically changes in the following manner: (1) changing the scanning speed of the laser beam, the shallow groove is increasing the scanning speed, and the deep groove is slowing down the scanning speed; (2) changing the illumination intensity of the laser beam, the shallow groove is to reduce the intensity of the illumination, the deep groove is to enhance the illumination intensity; and (3) the pulse interval of the laser beam is changed, the shallow groove is the pulse interval, and the deep groove is shortened. Pulse interval. A method of dividing a brittle material substrate according to claim 4, wherein in the step of forming the groove, the periodic groove is formed and a periodic crack is formed at the bottom of the periodic groove, and a bending moment is applied to the periodic groove and the periodic crack. A method of dividing a substrate of a brittle material according to claim 4 or 5, wherein the heating condition in the step of forming the groove periodically changes the depth of the focus of the laser beam. The method for dividing a brittle material substrate according to claim 4 or 5, wherein the wavelength of the periodic groove is 1 mm to 10 mm, and the difference between the maximum depth and the minimum depth of the periodic groove is 1% to 5% of the thickness of the substrate. . The method for dividing a brittle material substrate according to claim 4 or 5, wherein the brittle material substrate is a sapphire substrate.