TWI406828B - Method for processing brittle material substrates - Google Patents

Abstract

The present invention provides a method for processing substrate made of brittle material. A crackle which penetrates into the inner part of substrate can be reliably formed at the correct position along a preset dividing line. The method for processing substrate made of brittle material uses a heating step and a cooling step for forming the crackle. The heating is executed with a mode that the beam spot (BS) moves relatively along the preset dividing line (P) according to the heating step. The cooling is executed with a mode that the cooling spot moves relatively along the track for scanningthe beam spots according to the cooling step. The cooling step comprises the following procedures executed sequentially: (a) a first cooling procedure for relatively moving the first cooling spot (CS1) which is reduced to smaller than the width of beam spots along with the beam spot thereby extending the shallow crackle (S2); and (b) a second cooling procedure for relatively moving the second cooling spot (CS2) which is extended to larger than the width of the beam spot along with the track for scanning the first cooling point, thereby penetrating the shallow crackle formed beforehand in the thickness direction of substrate.

Description

Method for processing brittle material substrate

The present invention relates to a processing method for partially brittle a substrate of a brittle material by irradiating a laser beam, and then cooling the heating portion to form a cracked material substrate using thermal stress (tensile stress) generated on the substrate.

Here, the brittle material substrate means a glass substrate, a ceramic of a sintered material, a single crystal germanium, a semiconductor wafer, a sapphire substrate, a ceramic substrate, or the like.

Further, the "crack" is a scribe line before the front end in the depth direction reaches the back surface of the substrate, and is a dividing line (full cut line) when it reaches the back surface of the substrate. In the case of scribing, it is divided by performing a dividing process of applying a bending moment along a scribe line, or applying a crack so as to further penetrate the deeper portion of the substrate to divide it.

In the following description, for the sake of convenience of explanation, the term "intrusion of cracks" refers to a state in which cracks advance in the depth direction (thickness direction) of the substrate, and the state in which the cracks advance in the direction of the surface of the substrate (referred to as "cracking" Extension") is used differently.

In the following description, "slighter crack" means that the front end in the depth direction does not reach the crack on the back surface of the substrate (that is, the scribe line is formed), and the direct bending must apply a large bending moment along the crack, so the crack must be made. A crack that enters and then divides in the thickness direction.

A brittle material substrate such as a glass substrate can be used after being processed into an appropriate size or shape in various products. For example, the liquid crystal display panel is usually formed by a large-area mother board which is bonded to two glass substrates, and a liquid crystal is injected into the gap between the two glass substrates, and then cut into individual unit display substrates. production.

In the step of dividing the glass substrate, for example, as described in Patent Document 1, a method is employed in which a cutter wheel is moved while facing a substrate crimping cutter wheel, whereby a scribe line is drawn on the substrate, and then along the stroke The wire applies a bending moment in the thickness direction of the substrate to be broken.

When a scribing line (crack) is formed using a cutter wheel, it is possible to generate glass swarf in the vicinity of the scribe line in addition to the vertical crack entering in the thickness direction. In the case where a plurality of scribe lines are formed vertically and horizontally on the mother board, that is, a large-area glass substrate, the cumulative length of the scribe line formed by the cutter wheel becomes extremely long in the case of cutting a small unit substrate. As the cumulative length becomes longer, the probability of generating glass swarf becomes higher, and the amount of glass swarf is also increased. Once the glass swarf is generated, it is necessary to frequently clean the scribe line forming device (crack forming device) or the swarf on the platform of the breaking device that applies a bending moment to the substrate along the scribe line.

On the other hand, as a processing method capable of suppressing the amount of generation of glass swarf, in recent years, the following laser scribing method has been put into practical use (see Patent Document 2), which uses a laser beam to irradiate a laser beam. Forming a beam spot, and stepping on the substrate by a step of locally heating below the softening temperature of the substrate by scanning the beam spot along a predetermined scribe line and partially spraying the refrigerant along a trajectory passing through the beam spot Thermal stress is used and the thermal stress is used to form a scribe line.

However, when a small unit substrate is cut out from the mother board, it is necessary to perform a cross scribe which forms a scribe line vertically and horizontally, and when the cross scribe line is performed by the laser scribe line method, near the intersection of the scribe line Sometimes there are large cracks (bad cracks) that cause defects in the product. In order to prevent this situation, there is The condition for controlling the laser scribing is revealed such that the depth of the vertical crack in the second direction is shallower than the depth of the vertical crack in the first direction (refer to Patent Document 3). Specifically, it is disclosed that the laser output when suppressing the formation of the scribe line in the second direction is compared with the first direction, or the scanning speed of the second direction is faster than the scanning speed of the first direction, thereby controlling the depth of the vertical crack .

In this case, when a vertical crack in the first direction is formed, the crack must be made deep. As described in the above documents, the heat input is increased by increasing the output of the laser irradiation to increase the heat input or reducing the scanning speed of the laser to increase the heating time per unit length. The temperature of the substrate increases as the amount of heat increases, and the temperature difference increases after cooling, whereby a large thermal stress (tensile stress) can be generated, so that the crack can be deepened.

However, it is necessary to increase the heat input to the substrate to increase the substrate temperature, but it may be desirable to avoid the substrate temperature rise depending on the product. Further, if the scanning speed is lowered to affect the productivity, it is preferable to form cracks as quickly as possible.

On the other hand, another method of making cracks deep (see Patent Document 4) has also been disclosed. First, the surface of the mother glass substrate is heated in two stages by the beam point where the thermal energy intensity is the largest at each end in the long axis direction. That is, after heating by a large thermal energy intensity, the large amount of heat initially applied is surely conducted to the inside during heating by a small thermal energy intensity. At this time, the surface of the substrate is not continuously heated with a large thermal energy strength, so that the surface of the substrate can be prevented from softening. In the case of such heating, since heat is transferred to the inside of the substrate, cooling is performed only by the refrigerant forming the cooling point (cooling point), and a sufficient thermal stress gradient cannot be obtained between the cooling point and the cooling point. Thus, deep vertical cracks cannot be formed.

Therefore, in order to efficiently and surely form the scribe line, the area after the beam spot is closer to the laser spot side than the cooling point (main cooling point), and along the scribe line region (for example, in the embodiment 1 of Patent Document 4) An auxiliary cooling point for pre-injecting refrigerant for cooling is formed at a distance of 55 mm from the rear end of the beam spot, and the refrigerant temperature of the auxiliary cooling point is set to be higher than the refrigerant temperature of the main cooling point, and the auxiliary cooling point is scanned and Main cooling point.

This auxiliary cooling point mitigates the extra thermal shock and allows the energy that would otherwise be lost due to thermal shock to be used for the formation of cracks. Fig. 6 is a view showing a state in which the substrate is heated by the beam spot BS along the dividing line P, and then the temperature distribution in the width direction (short axis direction) and the thermal stress change at each point in the auxiliary cooling and the main cooling are sequentially performed. . Fig. 6(a) is a plan view showing the positional relationship between the heating by the beam spot BS and the cooling of the auxiliary cooling point AS and the main cooling point MS.

As shown in Fig. 6 (a), after the beam spot BS is heated, the section orthogonal to the dividing line P at the position where the cooling is performed at the auxiliary cooling point AS at the rear is the A-A' section to assist the cooling point. The cross section orthogonal to the planned dividing line P when the AS performs cooling is a B-B' cross section, and the cross section orthogonal to the dividing planned line P when the main cooling point MS is cooled is a C-C' cross section.

Fig. 6(b) is a view showing the temperature distribution of the surface of the substrate on the A-A' cross section and the inside of the substrate (the intermediate point in the thickness direction), and the temperature distribution and thermal stress inside the substrate. After heating by the beam spot BS, the temperature distribution on the surface of the substrate is distributed with a temperature spike which is convex upward from the predetermined dividing line P, on the A-A' section which is to be cooled by the auxiliary cooling point AS at the rear. Moreover, in terms of the temperature distribution inside the substrate on the A-A' cross section and the thermal stress, after the beam spot BS passes, the center of the heat source The film is advanced toward the inside of the substrate on the division planned line P, and heat is radiated radially from the center of the heat source. As a result, an elliptical temperature distribution is formed, and compressive stress is applied from the vicinity of the substrate surface to the inside.

Fig. 6(c) is a view showing the temperature distribution of the surface of the substrate and the inside of the substrate on the BB' section, and the temperature distribution and thermal stress inside the substrate. In the BB' section which is cooled by the auxiliary cooling point AS, since the width of the auxiliary cooling point AS cooled on the surface of the substrate is the same as the width heated by the beam spot BS, it becomes the following state, that is, The vicinity of the surface of the substrate is gradually cooled in the entire width direction (short axis direction), so that the temperature peak is entirely lowered (in the figure, the broken line portion is a change due to cooling). At this time, the inside of the substrate has a spike that protrudes upward due to heat transferred from the surface to the inside of the substrate. Cooling with the auxiliary cooling point AS produces a weak tensile stress on the surface of the substrate, but the tensile stress generated at this time (due to insufficient stress concentration) still does not form cracks.

Fig. 6(d) is a view showing the temperature distribution of the surface of the substrate and the inside of the substrate on the C-C' cross section, and the temperature distribution and thermal stress inside the substrate. On the C-C' cross section cooled by the main cooling point MS, a large tensile stress is generated in the entire width direction (short axis direction) by strongly cooling the vicinity of the entire substrate surface by the main cooling point MS on the surface of the substrate. At this time, the inside of the substrate has a spike that protrudes upward due to heat transferred from the surface to the inside of the substrate, so that compressive stress is generated. As a result, in the state where the tensile stress caused by the auxiliary cooling point AS occurs, and further cooling is performed by the refrigerant forming the main cooling point MS, a strong tensile stress acts on the surface of the substrate. At this point, deep cracks will form.

In addition, it has been revealed that such auxiliary cooling is implemented, and auxiliary cooling is not implemented. However, the depth of the crack increases by about 10%.

[Patent Document 1] Japanese Patent Laid-Open No. Hei 11-116260

[Patent Document 2] Japanese Patent Publication No. 8-509947

[Patent Document 3] Japanese Patent Laid-Open Publication No. 2001-58281

Patent Document 4: WO2004/014625

In the case where the crack is deepened by the method described in Patent Document 4, the crack can be stably formed and the crack can be entered as compared with the case where the auxiliary cooling point is not acted, but the position of the crack in the width direction of the beam spot is The controllability is not sufficient, and it is difficult to accurately align the crack position with the division line. The reason is that the auxiliary cooling point mitigates the excess thermal shock as described above, so that the energy originally lost by the thermal shock is used for the crack formation, so that the weak tensile stress is generated on the surface of the substrate, but the crack is also caused. The second cooling point is formed after the passage of the main cooling point. Therefore, both the auxiliary cooling point and the primary cooling point affect the location of the crack formation position, and therefore, due to the shape of the two cooling points or the refrigerant injection pressure, the distance between the two cooling points, or even two cooling points Parameters such as the scanning speed will cause subtle changes in the position of the crack.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a processing method for forming cracks with higher stability than conventionally, and which can be deepened and which can accurately position the formed cracks along a predetermined dividing line.

In order to solve the above problems, the processing method of the present invention is to set a predetermined dividing line on a substrate of a brittle material, and to relatively move the beam spot of the laser beam along the dividing line to heat the substrate at a temperature lower than a softening temperature. Steps, along with the cooling point formed by the injection of the refrigerant along the sweep a method of processing a brittle material substrate that forms a crack along the dividing line by the relative movement of the trajectory of the beam spot, and the cooling step is performed continuously (a) the first cooling step and (b) the second cooling In the step (a), the first cooling step is such that the first cooling point formed by reducing the width of the cooling point to be smaller than the width of the beam spot is followed by the relative movement of the beam spot, thereby causing the shallow crack to extend. The second cooling step (b) is such that the second cooling point formed by expanding the width of the cooling point to be larger than the width of the beam spot is relatively moved along the trajectory of scanning the first cooling point, thereby forming the previously formed The shallower cracks enter along the thickness of the substrate.

According to the present invention, the beam spot is relatively moved along a dividing line set on the substrate (i.e., moving the beam spot relative to the substrate, or moving the substrate relative to the beam spot), thereby locally heating the substrate. After heating, the quenching process is performed by first moving to the first cooling point having a width smaller than the width of the beam spot in such a manner as to follow the beam spot. The state immediately after the beam spot is moved is a state in which only the vicinity of the surface through which the beam point passes is heated. Therefore, the first cooling point is quenched in the vicinity of the beam spot, and only a large thermal stress (tensile stress) is generated near the top of the dividing line and near the surface, and thus will be along the dividing line. Cracks are formed accurately, and cracks do form. Then, by expanding the width of the cooling point to a second cooling point formed larger than the width of the beam spot, the entire cooling beam point passes through the region where the temperature rises. At this time, the cooling area becomes large, and a large tensile stress is applied to the entire portion cooled by the second cooling point. In the region where the first cooling step has been formed with a shallow crack, a large tensile stress is applied, and as a result, the shallow crack will penetrate deeper in the depth direction.

That is, a shallow crack is formed in the first cooling step to form a crack at a precise position along the line to be divided, and further penetrates from the previously formed shallow crack in the second cooling step.

According to the present invention, the steps of forming a shallow crack and the step of forming a deep crack are continuously performed by cooling points of two different conditions, whereby the crack can be stably formed at an accurate position along the dividing line, and Make the cracks deeper.

In the above invention, it is preferable that the thermal energy intensity in the width direction of the beam spot is maximized at the center of the beam spot.

Thereby, the center of the beam spot is heated to the maximum, and when the first cooling point is cooled, the temperature difference in the center of the beam spot is the largest, so that the concentrated portion of the thermal stress (tensile stress) is the center of the beam spot, that is, the dividing line. Therefore, a shallow crack can be accurately formed along the dividing line.

In the above invention, the first cooling step preferably forms a pair of high temperature regions on the left and right sides of the in-plane temperature distribution perpendicular to the planned dividing line just after the first cooling point passes, and performs cooling to divide A predetermined minimum temperature region is formed on the predetermined line at a temperature lower than the high temperature region, and a shallow crack is formed by thermal stress generated by a temperature difference between the pair of high temperature regions and the extremely small temperature region.

Thereby, the temperature distribution perpendicular to the plane of the planned dividing line becomes a shape in which the extremely small temperature region is sandwiched between the two temperature peaks (high temperature region), and thus the thermal stress (tensile stress) is concentrated in a region having a very small temperature, which is at a temperature Very small areas form cracks accurately.

In the above invention, the refrigerant may be contained in the refrigerant, and the first cooling point may be formed by spraying a mist jet that sprays the refrigerant that atomizes the water. The second cooling point is formed by gasification cooling in which a large amount of water is vaporized and then self-cooled and the temperature is lower than that of the above-described atomizer.

Here, the term "atomized refrigerant" means that a refrigerant containing moisture is concentratedly sprayed toward a small area, and is ejected from a nozzle in a state where it is difficult to vaporize, and the self-cooling phenomenon caused by vaporization of moisture does not occur and is ejected. The state of the refrigerant. When the atomized refrigerant is used, since the self-cooling does not occur, the temperature of the refrigerant does not decrease, and the smaller area can be concentrated and cooled.

The term "gasification cooling" refers to a method in which a refrigerant containing moisture is sprayed so as to diffuse moisture, and is ejected from a nozzle in a state where it is easily vaporized, and the self-cooling phenomenon caused by vaporization of water in the refrigerant causes the temperature of the refrigerant to decrease. It is cooled by a low temperature refrigerant. With gasification cooling, it is difficult to centrally cool a small area, but it is possible to cool a wide area at a low temperature.

With the present invention, local cooling can be easily performed by atomized refrigerant, and on the other hand, a wide range can be strongly cooled by the vaporized cooling refrigerant.

In the above invention, it is preferable that the relative movement speed of the beam spot, the first cooling point, and the second cooling point is 100 mm/sec to 720 mm/sec.

According to the present invention, although the thickness, the material, and the processing method are different, the step of forming the shallow crack and the step of forming the deep crack are continuously performed, and the speed is increased from 100 mm/sec to 720 mm/sec. It is also possible to form a crack along the line to be divided, so that cracks can be formed at a high speed.

Hereinafter, embodiments of the present invention will be described based on the drawings. Fig. 1 is a schematic configuration diagram of a substrate processing apparatus LS1 according to an embodiment of the present invention. Here, a case where a glass substrate is processed will be described as an example.

First, the overall configuration of the substrate processing apparatus LS1 will be described. The pair of guide rails 3, 4 are arranged along the horizontal gantry 1 in parallel with each other, and are provided with a slide table 2 which reciprocates in the front-back direction (hereinafter referred to as the Y direction) of the paper of Fig. 1. A lead screw 5 is disposed between the two guide rails 3 and 4 in the front-rear direction, and a fixing member 6 fixed to the slide table 2 is screwed to the lead screw 5, and is guided by a motor (not shown). The screw 5 rotates positively and negatively to reciprocate the slide table 2 along the guide rails 3, 4 in the Y direction.

A water platform seat 7 that reciprocates along the guide rail 8 in the left-right direction (hereinafter referred to as the X direction) of FIG. 1 is disposed on the slide table 2. A lead screw 10 that is rotated by a motor 9 is screwed into a bracket 10a fixed to the pedestal 7, and the pedestal 7 is reciprocated along the guide rail 8 in the X direction by the forward and reverse rotation of the lead screw 10.

The turret 7 is provided with a turntable 12 that is rotated by a rotating mechanism 11, and a brittle material substrate such as a glass substrate A is attached to the turntable 12 in a horizontal state. The glass substrate A is used, for example, for cutting out a mother board of a small unit substrate. The rotating mechanism 11 rotates the turntable 12 about a vertical axis and is rotatable so as to be at an arbitrary rotation angle with respect to the reference position. Further, the glass substrate A is fixed to the turntable 12 by a suction chuck.

Above the turntable 12, the laser device 13 and the optical holder 14 are held on the mounting frame 15.

The laser device 13 may be a conventional laser device for processing a brittle material substrate, and specifically, an excimer laser, a YAG laser, a carbon dioxide laser, or a carbon monoxide laser may be used. In the processing of the glass substrate A, it is preferred to use a carbon dioxide laser which can oscillate light of a wavelength at which the energy absorption efficiency of the glass material is large.

The laser beam emitted from the laser device 13 has a beam spot of a predetermined shape and is irradiated onto the glass substrate A by an optical holder 14 in which a lens optical system for adjusting the shape of the beam is assembled. The shape of the beam spot is excellent in that the shape of the long axis (elliptical shape, oblong shape, or the like) can be efficiently heated along the dividing line, but it can be performed at a temperature lower than the softening temperature. The shape of the heating, the shape of the beam spot is not particularly limited.

In the present embodiment, a beam spot having an elliptical shape is formed. Fig. 2 is a plan view (a) showing a beam spot of an elliptical shape irradiated and a heat intensity distribution (b) in the width direction (short axis direction). The thermal energy intensity distribution in the width direction of the beam spot BS, such as a Gaussian distribution, is distributed to the left and right symmetry and the thermal energy of the center of the beam spot is maximum. When the beam spot BS moves on the substrate, the trajectory of the central portion of the beam spot BS passes. It is heated to the highest temperature (but below the softening temperature). Regarding the thermal energy intensity distribution in the long axis direction of the beam spot BS, it may be a Gaussian distribution, or a thermal energy intensity distribution of different distribution shapes for improving the heating efficiency.

In the mounting frame 15, the proximity optical holder 14 is provided with a first cooling nozzle 16a and a second cooling nozzle 16b. The refrigerant is ejected by the cooling nozzles 16a, 16b. As the refrigerant, cooling water, compressed air, helium gas, carbon dioxide or the like can be used. In the present embodiment, a mixed fluid of cooling water and compressed air is sprayed.

The refrigerant ejected from the first cooling nozzle 16a is irradiated toward the end portion in the longitudinal direction of the beam spot BS of the glass substrate A from the optical holder 14, and a first cooling point CS1 is formed on the surface of the glass substrate A. The refrigerant injected from the first cooling nozzle 16a is sprayed by the nozzle so as to be misted.

The refrigerant injected from the second cooling nozzle 16b is formed on the surface of the glass substrate A toward the rear end of the first cooling point CS1, or at a position partially overlapping the first cooling point, or slightly away from the rear end of the first cooling point CS1. Second cooling point CS2. Since the refrigerant injected from the second cooling nozzle 16b is sprayed by the nozzle in a wide range of diffusion, the moisture can be vaporized and cooled efficiently.

3 is a plan view showing the positional relationship and the dimensional relationship between the beam spot BS, the first cooling point CS1, and the second cooling point CS2 formed along the dividing line P on the glass substrate A.

The beam spot BS, the first cooling point CS1, and the second cooling point CS2 are all elliptical or oblong with a long axis, and the major axis directions are coaxial with the planned dividing line P, respectively. If the width (short axis) of the beam spot BS is W _B , the width of the first cooling point is W _CS1 , and the width of the second cooling point is W _CS2 , the magnitude of the width is W _CS1 <W _B ≦W _CS2 .

Specifically, the width W _{CS1 of the} first cooling point CS1 is set to be about 1/4 to 3/4 of the width W _B of the beam spot BS, and more preferably about 1/2. For example, when the width (short axis) of the beam spot BS is set to 2 mm, the short axis of the first cooling point CS1 is set to 1 mm for ejection.

Further, the width W _{CS2 of the} second cooling point CS2 is set to be the same as the width W _{B of the} beam spot BS, or slightly wider than W _B . For example, when the width (short axis) of the beam spot BS is set to 2 mm, the short axis of the second cooling point CS2 is set to be about 3 mm for ejection.

Further, the cutter wheel 18 is attached to the mounting frame 15 via the vertical movement adjustment mechanism 17. The cutter wheel 18 is configured such that when the initial crack (trigger point) is formed at the edge of the glass substrate A, the pedestal 7 is temporarily moved downward in the X direction. Use after the fall.

Further, a camera 20 capable of detecting an alignment mark for positioning on the glass substrate A is mounted on the substrate processing apparatus LS1, and a predetermined dividing line can be obtained from the position of the alignment mark detected by the camera 20. P position and position.

Next, the processing operation of the substrate processing apparatus LS1 will be described. The glass substrate A is placed on the turntable 12 and fixed by a suction chuck. The alignment mark imprinted on the glass substrate A is detected by the camera 20, and based on the detection result, the positional relationship between the planned dividing line P, the rotary table 12, and the slide table 2 is established. Thereafter, the positions of the rotary table 12 and the slide table 2 are adjusted so that the division planned line P reaches a position opposed to the cutter wheel 18.

Then, in order to form the initial crack TR at the end portion of the glass substrate A, the turntable 12 is returned to the initial position (the right end in FIG. 1), and the turntable 12 is turned to the -X direction in a state where the cutter wheel 18 is lowered. (moving from right to left in Fig. 1), the cutter wheel 18 is crimped to the side end of the glass substrate A to form an initial crack (TR).

After the initial crack (TR) is formed, the turntable 12 is returned to the initial position again, and the laser beam is emitted from the laser device 13, and the refrigerant is ejected from the first cooling nozzle 16a and the second cooling nozzle 16b.

In this state, the rotary table 12 is moved in the -X direction (from right to left in Fig. 1). Thereby, the beam spot BS, the first cooling point CS1, and the second cooling point CS2 are scanned in this order along the predetermined dividing line P of the glass substrate A.

The following state will be described, that is, by the above operation, the predetermined line P is divided along the glass substrate A and the initial crack TR is used as a starting point. The crack is a state in which the crack generated in the glass substrate A enters the inside of the substrate due to the cooling of the first cooling point CS1 and the second cooling point CS2.

4 is a view showing the temperature in the width direction (short axis direction) at each point when the substrate is heated by the beam spot BS along the dividing line P, and the cooling is performed by the first cooling point CS1 and the second cooling point CS2. Schematic diagram of distribution changes and stress changes. Fig. 4 (a) is a plan view showing the positional relationship of the region heated by the beam spot BS and cooled by the first cooling point and the second cooling point.

As shown in FIG. 4(a), after the first cooling point CS1 is cooled by the beam spot BS, the section orthogonal to the dividing line P in the vicinity of the first cooling point CS1 is D-D'. When the cooling point CS1 is cooled, the cross section orthogonal to the dividing line P is an E-E' cross section, and when the cooling point CS2 is cooled, the cross section orthogonal to the dividing line P is a F-F' cross section.

Fig. 4(b) is a temperature distribution diagram of the surface of the substrate on the DD' section, and a schematic diagram showing the temperature distribution and thermal stress inside the substrate. After heating by the beam spot BS, on the D-D' section near the front where the first cooling point CS1 is cooled, since the thermal energy intensity of the beam spot BS is distributed at the center at the maximum, the temperature distribution of the substrate surface is presented. There is a distribution of temperature spikes that protrude upward from the predetermined dividing line P. Further, in the D-D' cross section, the temperature distribution and the thermal stress in the substrate are radially radiated from the substrate surface side centering on the planned dividing line P, so that a semicircular temperature distribution is formed as a result. The vicinity of the surface of the substrate is subjected to compressive stress.

Fig. 4(c) is a diagram showing the temperature distribution of the substrate surface and the inside of the substrate on the E-E' cross section, and the temperature distribution and thermal stress inside the substrate. On the E-E' section that has been cooled by the first cooling point CS1, The width of the surface of the substrate cooled by the first cooling point CS1 is reduced to be smaller than the width of the beam spot BS. Therefore, the temperature distribution changes to a valley at the center of the temperature peak (a very small temperature region), so that it becomes 2 The temperature distribution of a spike. As a result, a large thermal stress (tensile stress) is locally generated above and near the surface of the division planned line P, so that a crack is formed on the surface. On the other hand, since the inside of the substrate is locally heated by the beam spot BS, the heat transferred from the substrate surface is not sufficiently transmitted to the inside of the substrate, so that temperature rise is less likely to occur inside the substrate. As a result, only a large thermal stress generated in the vicinity of the surface of the substrate causes cracks to be formed in the vicinity of the surface of the substrate, but since the crack does not enter the inside of the substrate, a shallow crack is formed as a result.

Fig. 4(d) is a diagram showing the temperature distribution of the substrate surface and the inside of the substrate on the F-F' cross section, and the temperature distribution and thermal stress inside the substrate. On the F-F' section cooled by the second cooling point CS2, the width of the surface of the substrate cooled by the second cooling point CS2 is the same as the width of the beam spot BS, or is wider than the width of the beam spot BS. Therefore, the temperature peak is cooled as a whole, so the temperature spike disappears, and a large thermal stress (tensile stress) is formed on the entire surface. On the other hand, heat transferred from the surface remains in the inside of the substrate, and as a result, a large temperature difference is generated over the entire surface of the substrate and the surface of the substrate. This temperature difference causes tensile stress on the surface of the substrate, and compressive stress is generated inside the substrate, whereby the force of cracking of the previously formed shallow crack is generated due to the surrounding stress distribution, and the shallow crack is further exerted. .

Fig. 5 is a schematic view showing a state in which cracks are generated in a cross section along the direction of dividing the predetermined line P.

As described so far, in the region L1 heated by the beam spot BS, although a compressive stress perpendicular to the direction of the paper surface is applied in the vicinity of the surface, no crack is generated.

In the region L2 cooled by the first cooling point CS1, a local tensile stress perpendicular to the direction of the paper surface is generated in the vicinity of the surface (refer to Fig. 4(c)) to form a shallow crack S2.

Further, in the region L3 cooled by the second cooling point CS2, the compressive stress in the direction perpendicular to the paper surface inside the substrate and the tensile stress in the direction perpendicular to the paper surface of the substrate surface are made shallower in the vicinity of the surface. The crack S2 further enters the force (see Fig. 4(d)), thereby forming a deep crack S3.

In this way, the first stage is stable and does form a shallow crack, which serves as a trigger point to make the crack deep in the second stage, thereby stably stabilizing the beam spot BS or the like even at a speed higher than the current speed. Form deep cracks. Specifically, even in the case of a glass substrate in which cracks cannot be stably formed at a speed of 100 mm/sec or more, cracks can be stably formed at a speed of 720 mm/sec or less.

For example, when the CO ₂ laser is irradiated for scribing, conventionally, the scribing process can be performed only at a scanning speed of 240 W and 500 mm/sec or less. However, by using the present invention, the scanning speed is accelerated even to the same substrate. Processing is also possible at 550 mm/sec. As a result, cross cutting can be realized at high speed. Moreover, high-speed crack formation of up to 720 mm/sec has also been experimentally confirmed.

Further, with the present invention, cracks can be made deeper than before. As a result, in the related art, the breaking device is used to break the substrate by pressing the breaking bar along the crack (scribe line), and according to the present invention, it is not necessary to perform such a breaking step. The substrate is cut and the overall cutting without the breaking step can be achieved.

The present invention can be applied to the formation of cracks on a brittle material substrate such as a glass substrate, and is further used for division.

A‧‧‧Glass substrate (brittle material substrate)

BS‧‧‧beam point

CS1‧‧‧First cooling point

CS2‧‧‧second cooling point

P‧‧‧ dividing line

S2‧‧‧ shallower crack

S3‧‧‧In-depth crack

2‧‧‧Slide table

12‧‧‧Rotating table

13‧‧‧ Laser device

14‧‧‧Optical holder

16a‧‧‧First cooling nozzle

16b‧‧‧second cooling nozzle

Fig. 1 is a schematic configuration diagram of a substrate processing apparatus using the processing method of the present invention.

Fig. 2 is a view showing an example of a thermal energy intensity distribution of a laser beam.

3 is a plan view showing a positional relationship between a beam spot, a first cooling point, and a second cooling point.

4 is a schematic view showing changes in temperature distribution and stress changes in the width direction (short axis direction) at each point when the substrate is heated by the beam spot and the first cooling point CS1 and the second cooling point CS2 are cooled.

Fig. 5 is a view showing a state in which a crack is generated in a cross section along a direction in which a predetermined line is divided.

Fig. 6 is a view showing a change in temperature distribution and a change in thermal stress in the width direction (short axis direction) at each point when the substrate is heated by the beam spot, and then the auxiliary cooling is performed.

BS‧‧‧beam point

CS1‧‧‧First cooling point

CS2‧‧‧second cooling point

S2‧‧‧ shallower crack

S3‧‧‧In-depth crack

13‧‧‧ Laser device

14‧‧‧Optical holder

16a‧‧‧First cooling nozzle

16b‧‧‧second cooling nozzle

L1‧‧‧A zone heated by beam spot BS

L2‧‧‧A zone cooled by the first cooling point CS1

L3‧‧‧A region cooled by the second cooling point CS2

Claims (5)

A method for processing a substrate of a brittle material, which is used for setting a predetermined dividing line on a substrate of a brittle material, and causing a beam point of the laser beam to relatively move along the dividing line to heat the substrate at a temperature lower than a softening temperature. a method for processing a brittle material substrate that forms a crack along the predetermined dividing line, and a cooling step of cooling the cooling point formed by the refrigerant jet along the trajectory of the scanning beam spot, wherein the cracking material substrate is formed by the cooling line The cooling step is continuously performed as follows: (a) a first cooling step and (b) a second cooling step, wherein the (a) first cooling step is formed by reducing a width of the cooling point to be smaller than a width of the beam spot. a cooling point follows the beam spot for relative movement, thereby causing the shallow crack to extend, and the (b) second cooling step is to expand the width of the cooling point to be greater than the width of the beam spot. The points are moved relative to each other along the trajectory of scanning the first cooling point, thereby allowing the previously formed shallower cracks to enter in the thickness direction of the substrate. The method for processing a brittle material substrate according to claim 1, wherein the thermal energy intensity in the width direction of the beam spot is maximized at the center of the beam spot. The method for processing a substrate of a brittle material according to claim 1, wherein the first cooling step is cooled in such a manner as to be sandwiched by a temperature distribution in a plane perpendicular to the dividing line of the first cooling point. The dividing line is formed on the left and right sides to form a pair of high temperature regions and is cooled A temperature extremely small region having a temperature lower than a low temperature of the high temperature region is formed on the division planned line, and a shallow crack is formed by thermal stress generated by a temperature difference between the pair of high temperature regions and the temperature minimum region. The method for processing a brittle material substrate according to the first aspect of the invention, wherein the refrigerant contains moisture, and the first cooling point is formed by spraying a spray of a refrigerant that atomizes the water, and the second cooling point is widely used. The blasting is formed by vaporizing and cooling the water after self-cooling and lowering the temperature of the refrigerant lower than the atomizer. The method for processing a brittle material substrate according to claim 1, wherein the relative movement speed of the beam spot, the first cooling point, and the second cooling point is 100 mm/sec to 720 mm/sec.