KR101165982B1 - Method for processing fragile material substrate - Google Patents

Abstract

An object of the present invention is to provide a method for processing a brittle material substrate capable of performing a stable laser brake treatment. (a) an initial crack forming step of forming an initial crack on a scribing scheduled line near the first substrate end; and (b) a beam spot of the first laser irradiation from the first substrate end side. The scribe line of the finite depth along the scribing scheduled line is cooled along the second substrate end by heating relative to the second substrate end, cooling the portion immediately after the passage of the beam spot, and using the stress gradient in the depth direction generated in the scribing scheduled line. A laser scribing process for forming a film, and (c) relatively shifting the beam spot of the second laser irradiation from the second substrate end to the first substrate end along the scribe line to penetrate the scribe line more deeply, or It is processed by the laser brake process which divides completely.

Description

Processing method of brittle material substrate {METHOD FOR PROCESSING FRAGILE MATERIAL SUBSTRATE}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for processing a brittle material substrate by laser irradiation. More particularly, the present invention relates to a scribe comprising a fin of a finite depth on a substrate by irradiating a first laser beam along a scribe schedule line set on the substrate. A method of processing a brittle material substrate is formed by forming a line and then irradiating a second laser beam to deeply penetrate this scribe line or to completely divide it.

Here, a brittle material substrate means a glass substrate, ceramics of a sintered material, single crystal silicon, a semiconductor wafer, a sapphire substrate, a ceramic substrate, etc.

When a laser beam is irradiated to a brittle material substrate such as a glass substrate, the beam spot formed on the substrate is scanned, heated in a line shape, and a laser scribing process is further performed by spraying a coolant immediately after the heating. In comparison with the mechanical processing by this, generation | occurrence | production of a cullet can be reduced and cross-sectional strength can be improved.

Therefore, laser scribing is employ | adopted in various manufacturing processes which require the division | segmentation of a glass substrate etc. as well as a flat panel display.

Generally, in laser scribing, an imaginary line (called a scribe scheduled line) to be divided from now on is set. From the position of the initial crack in which an initial crack was formed at the substrate end, which is the beginning of the scribe scheduled line, with a cutter wheel or the like, and a beam spot and a cooling spot (region where the refrigerant is injected) were formed at the beginning. Scan along the scheduled scribe line. At this time, as a result of the stress gradient generated on the basis of the temperature distribution generated near the scribe scheduled line, line-shaped cracks are formed (see Patent Document 1, Patent Document 2, and Patent Document 3).

By the way, in the line-shaped crack formed by scanning a laser beam with respect to a brittle material substrate, the "finite depth crack" in which the front-end | tip of a crack depth does not reach the back surface of a board | substrate, and the crack reaches the back surface of a board | substrate, There exists a "through crack" (for example, refer patent document 2) which divides a board | substrate at once.

The cutting line formed by the former "crack of finite depth" is called a scribe line, and the dividing line by the latter through crack is called a full cut line. These are formed by different mechanisms.

8 is a cross-sectional view of a substrate that schematically illustrates the mechanism by which cracks of finite depth are formed. That is, compressive stress HR generate | occur | produces in the board | substrate GA as shown to FIG. 8 (a) by preceding laser heating. Next, as a result of cooling after heating, tensile stress CR is generated on the substrate surface as shown in Fig. 8B. At this time, the compressive stress HR moves inside the substrate by the movement of heat, and an internal stress field Hin is formed. As a result, as shown in FIG.8 (c), the stress gradient of a depth direction generate | occur | produces and the crack Cr is formed.

Under the conditions in which the cracks Cr are formed by the above mechanism, since the compressive stress field Hin existing inside the substrate blocks further penetration of the cracks Cr in the depth direction, the cracks Cr By stopping just before the internal compressive stress field Hin, the crack Cr becomes a finite depth in principle. Therefore, in order to completely divide a board | substrate, after a scribe line of finite depth by the crack Cr is formed, you must perform a brake process further. On the other hand, the processing cross section of the scribe line by crack Cr is very beautiful (the surface unevenness | corrugation is small), and also it is excellent in linearity, and is an ideal state as a processing cross section.

Fig. 9 is a perspective view (Fig. 9 (a)) and a plan view (Fig. 9 (b)) of the substrate, which schematically show a mechanism in which the through cracks are formed. In other words, the compressive stress HR is generated on the surface of the substrate by the beam spot BS of the laser beam scanned from the position of the initial crack TR. At the same time, tensile stress CR is generated on the substrate surface by the cooling spot CS behind the beam spot BS. As a result, a stress gradient in the front-rear direction is formed on the scan line (on the scribe plan line L), and through this stress gradient, a force for tearing the substrate from side to side in the scan line direction acts to form a through crack. The substrate is divided.

When this "penetration crack" is formed, it is convenient in that a board | substrate can be segmented (full cut) without performing a brake process, and division by this mechanism may be desired depending on a processing use, Compared with the processing cross section of the scribe line mentioned above, the linearity of the processing cross section of a full cut line may be impaired, and also the quality (unevenness | corrugation of surface) of the cross section of a full cut line is compared with the scribe line mentioned above. Falls.

In addition, whether a scribe line is formed or a full cut line is formed by laser scribing, heating conditions (laser wavelength, irradiation time, output power, scanning speed, etc.), cooling conditions (refrigerant temperature, injection amount, injection position, etc.), It depends on the thickness of the substrate and the like. Generally, when the plate | board thickness of a glass substrate is thin, it becomes easy to become a full cut line compared with the case where it is thick, and the process window of the processing conditions which can form a scribe line is narrow.

In view of the above, in the case where it is desired to perform the segmentation processing excellent in the cross-sectional quality with respect to the glass substrate or the like, laser scribing is performed under the condition of the mechanism in which the scribe line is formed, not the full cut line, and then the brake process is performed. To do it.

As a brake processing method performed after laser scribing, a mechanical brake processing in which a brake bar or the like is applied to a scribe line to apply a bending moment may be used. In the case of mechanical brake processing, when a large bending moment is applied to the substrate, cullets may occur. Therefore, in the manufacturing process which avoids generation | occurrence | production of a cullet, it is necessary to form a scribe line as deep as possible, and to make it possible to apply a brake process only by applying a small bending moment.

Then, the second laser irradiation is performed along the scribe line formed by the laser scribing process to further penetrate the crack of a finite depth (in this case, further mechanical brake treatment), or to penetrate the crack to the rear surface. The laser brake process of dividing is performed (for example, refer patent document 1-patent document 3).

Japanese Laid-Open Patent Publication No. 2001-130921 Japanese Laid-Open Patent Publication No. 2006-256944 WO2003 / 008352 publication

Thus, by performing the laser scribing process which forms a scribe line by the 1st laser irradiation, and performing a laser brake process by the 2nd laser irradiation, the division process which suppressed generation | occurrence | production of a cullet becomes possible. However, when the scribe line formed by laser scribing, that is, the first laser irradiation, is shallow, it is difficult to reach the cracks to the back surface of the substrate by a later laser brake process. Therefore, in order to cut | disconnect a board | substrate completely by a laser brake process, it is necessary to form a deep scribe line at the time of a laser scribing process.

In addition, even when the substrate is not completely divided by the laser brake process, it is preferable to form a scribe line at least a little deeper in the laser scribing process, since it becomes easier to make a deeper scribe line by a later laser brake process. Do.

By the way, when it is going to form a scribe line deeper than before by laser scribing, it is necessary to change the heating conditions and cooling conditions at the time when the scribe line was formed so far. Specifically, the stress in the depth direction generated in the substrate is increased by increasing the laser output to increase the amount of heat input by heating or to increase the amount of refrigerant injection during cooling, and to be a radical condition where a temperature difference in the depth direction tends to occur more than ever. The gradient needs to be increased.

However, when attempting to shift to a heating condition and a cooling condition that increase the stress gradient in the processing order of the conventional laser scribing process, the first laser irradiation does not form a deep scribe line, and the cracks penetrate the substrate instead. (Move to the mechanism through which the through cracks are formed), a full cut line is formed. That is, by appropriately selecting the heating conditions and cooling conditions at the time of laser scribing, a shallow scribe line can be formed relatively easily, but trying to form a deep scribe line, a little from the conditions which have previously used heating conditions and cooling conditions. Even if you try to change to extreme conditions, the range of settable heating conditions and cooling conditions does not exist, or even if they exist, the settable range (process window) is narrow and unstable, and the transition to the condition that a full cut line is formed suddenly occurs. It was difficult to form a deep scribe line as expected.

Therefore, in the present invention, when the scribe line is formed on the substrate by laser scribing, the laser break treatment is performed to completely break the substrate or to form a deeper scribe line. It is an object to provide a processing method of a material substrate.

Moreover, an object of this invention is to provide the processing method of a brittle material board | substrate which can perform the division | segmentation process excellent in the cross-sectional quality of a process cross section stably.

This invention is made | formed by observing the process surface formed by laser scribing, and examining the characteristic. That is, the processing method of the brittle material substrate of the present invention, which is made to solve the above problems, has two lasers in the following order along the scribe scheduled line from the first substrate end set to the brittle material substrate to the second substrate end. The substrate is processed by performing irradiation.

(a) First, an initial crack forming step of forming an initial crack on a scribe scheduled line near the first substrate end is performed. At this time, it may be formed at the substrate end (first substrate end) similarly to the initial crack in the conventional laser scribing process, but may be formed inside the substrate on the scribe scheduled line near the substrate end.

(b) Subsequently, the beam spot of the first laser irradiation is moved relatively from the first substrate end side to the second substrate end along the scribe scheduled line, and the substrate is heated to a softening temperature or less, and the beam spot A coolant is injected and cooled at a portion immediately after passing through, and a laser scribing step of forming a scribe line having a finite depth along the scribe scheduled line is performed using a stress gradient in the depth direction generated in the scribe scheduled line.

At this time, by appropriately selecting the heating condition by the beam spot and the cooling condition by the cooling spot, a scribe line made of a finite depth crack formed based on the stress gradient in the depth direction is formed so as not to become a full cut line. do. Specifically, when the heating condition (e.g. increase in laser output) or the cooling condition (e.g. increase in refrigerant injection amount) becomes too severe, the temperature tends to become a full cut line rather than a scribe line. Conditions similar to those of the prior art, i.e., heating or cooling conditions, are not to be excessively severe.

(c) In addition, a laser brake process is performed in which the beam spot of the second laser irradiation is relatively moved in the reverse direction from the second substrate end to the first substrate end along the scribe line to further penetrate the scribe line. Or the laser brake process which penetrates a scribe line further deeply and is fully segmented is performed.

That is, it discovered that the local deep crack was formed in the 2nd board | substrate end which is a process termination when the laser scribe process of (b) is performed. When the laser brake process was performed starting from a deep crack, it discovered that the scribe line can be deepened compared with the laser brake process starting from a shallow crack.

Therefore, after performing the laser brake process by the 2nd laser irradiation after the laser scribe process of (b), it heats in a reverse direction along a scribe line from the 2nd board | substrate end in which local deep crack is formed. As a result, the crack starting from the deep crack existing at the second substrate end proceeds while maintaining the depth of the crack along the scribe line, and the depth of the crack formed at this time is equal to the deep crack near the second substrate end. It turned out that it can be made more than equal depth. By this method, a deeper scribe line can be formed more easily than when the second laser irradiation is performed in the same direction as the first laser irradiation, and the deep scribe line can reach and split to the back side. It turned out.

(Means and effects to solve other problems)

In the initial crack formation step of the invention (a), the initial crack is preferably formed so as to be spaced apart from the first substrate end.

By separating an initial crack from a 1st board | substrate end, a full cut line becomes difficult to form at the time of the laser scribe process of (b). Therefore, it is possible to change the heating conditions and cooling conditions in the laser scribing process to conditions where the temperature difference becomes larger than before (an intense condition than before), and the process window that can be set is widened, so that a deeper scribe line can be formed. Will be.

Moreover, compared with the case where an initial stage crack is formed in a 1st board | substrate end, generation | occurrence | production of the drift phenomenon which cannot control the direction of crack propagation can be reduced. As shown in Fig. 10, the initial crack TR formed at the start end is a start end (first substrate end) which is a substrate end on the side of starting the laser irradiation in the scribe scheduled line L. When heated by the beam spot BS, the crack K is formed in an uncontrollable direction toward the front of the beam spot starting from the heating area by the beam spot BS. When "winding forward" occurs, the scribe line along the scribe scheduled line L cannot be formed, and the straightness of the scribe line is remarkably impaired.

When an initial crack is formed in the first substrate end, when a deep scribe line is formed and the heating condition or the cooling condition is shifted to a more intense heating condition or a cooling condition, the frequency of occurrence of such "overrun" occurs. Although it tends to be high, the initial crack is spaced apart from the first substrate end, so that even when shifted to a somewhat intense heating condition or cooling condition, the rolling is not generated.

In the initial crack formation step (a), the initial crack may be formed by press-contacting a grooved cutter wheel having a periodic groove formed at the edge of the blade.

As the cutter wheel with a periodic groove, the high penetrating blade tip "penett" (registered trademark) and "APIO" (registered trademark) manufactured by Mitsubishi Diamond Co., Ltd. can be used specifically. .

By using a cutter wheel provided with a periodic groove at the blade tip, the blade tip becomes less slippery with respect to the substrate surface, and a short distance (about 1 mm to 2 mm) is applied when forming an initial crack at a position spaced apart from the substrate end. Only by making it hard, a stable initial crack can be formed.

Further, in the laser brake step of (c), when the beam spot of the second laser irradiation is relatively moved in the opposite direction from the second substrate end to the first substrate end along the scribe line, the front portion through which the beam spot passes. Cooling may be performed by injecting a coolant into the cooling medium.

As a result, a large temperature difference between the surface of the substrate and the inside of the substrate during the laser braking process can strongly generate compressive stress and tensile stress inside the substrate, and a tearing force in the depth direction acts. Deep cracks can penetrate deeper.

According to the present invention, by performing a laser brake process starting from a locally deep crack of the second substrate end formed in the laser scribing step, the deep scribe line can be advanced in the reverse direction along the scribe scheduled line. It is possible to form a deep scribe line simply and stably, and also to make it possible to perform segmentation simply.

In addition, since the laser brake process can be executed starting from a locally deep crack, the settable process window (range that can be set as a processing condition) can be widened during the laser brake process.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic block diagram of the substrate processing apparatus used when implementing the substrate processing method of this invention.
2 is a view showing the configuration of a cutter wheel with a periodic groove.
It is a figure which shows a part of the operation procedure of the machining method which is one Embodiment of this invention.
It is a figure which shows a part of the operation procedure of the machining method which is one Embodiment of this invention.
FIG. 5 is a photograph showing a divided section of a scribe line. FIG.
6 is a cross-sectional view schematically showing a stress gradient to be formed during laser brake processing.
Fig. 7 is a cross-sectional view schematically showing the traveling state of the divided surface when the laser crack processing is performed with the deep crack as the start end.
8 is a sectional view schematically showing a mechanism in which cracks of a finite depth are formed.
9 is a perspective view and a plan view schematically showing a mechanism in which a full cut line is formed.
FIG. 10 is a view illustrating a winding phenomenon occurring at the substrate end. FIG.

Best Mode for Carrying Out the Invention [

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the drawings.

First, an example of the substrate processing apparatus used when implementing the processing method of this invention is demonstrated.

1 is a schematic configuration diagram of a substrate processing apparatus LS1 capable of implementing the processing method of the present invention. Although the case where a glass substrate is processed is demonstrated as an example here, even if it is a brittle material substrate, such as a silicon substrate.

First, the whole structure of the substrate processing apparatus LS1 is demonstrated. A slide table which reciprocates in the front and rear direction of the paper (hereinafter referred to as the Y-direction) of FIG. 1 along a pair of guide rails 3 and 4 arranged in parallel on a horizontal stand 1 ( 2) is formed. The screw screw 5 is arrange | positioned along the front-back direction between both guide rails 3 and 4, The stay 6 fixed to the slide table 2 is screwed to this screw screw 5, By rotating the screw screw 5 forward and backward with a motor (not shown), the slide table 2 is formed to reciprocate along the guide rails 3 and 4 in the Y direction.

On the slide table 2, a horizontal pedestal 7 is arranged to reciprocate along the guide rail 8 in the left-right direction (hereinafter referred to as the X-direction) in FIG. The screw screw 10 rotated by the motor 9 is screwed through to the stay 10a fixed to the pedestal 7, and the screw screw 10a rotates forward and reverse, so that the pedestal 7 is rotated. Along the guide rail 8, it reciprocates in the X direction.

On the pedestal 7, the rotary table 12 which rotates by the rotary mechanism 11 is formed, and the glass substrate A is affixed on the rotary table 12 in the horizontal state. This glass substrate A is, for example, a mother substrate for cutting out a small unit substrate. The rotary mechanism 11 is configured to rotate the rotary table 12 around a vertical axis, and is formed so as to be able to rotate at an arbitrary rotational angle with respect to the reference position. In addition, the glass substrate A is fixed to the turntable 12 by the suction chuck.

Above the rotary table 12, the laser device 13 and the optical holder 14 are held by the attachment frame 15. As shown in FIG.

The laser device 13 may use a general thing for processing a brittle material substrate, and specifically, an excimer laser, a YAG laser, a carbon dioxide laser, a carbon monoxide laser, etc. are used. It is preferable to use the carbon dioxide laser which oscillates the light of the wavelength with the large energy absorption efficiency of a glass material for the process of the glass substrate A. FIG.

As for the laser beam radiate | emitted from the laser apparatus 13, the beam spot of a predetermined shape is irradiated on the glass substrate A by the optical holder 14 in which the lens optical system for adjusting a beam shape was integrated. The shape of the beam spot is excellent in that the shape having a long axis (elliptical shape, oblong shape, etc.) can be efficiently heated along the scribe scheduled line, but if the shape can be heated at a lower temperature than the softening temperature, The shape of the spot is not particularly limited. In this embodiment, an elliptic beam spot is formed.

In the attachment frame 15, a cooling nozzle 16 is formed in proximity to the optical holder 14. Coolant is injected from the cooling nozzle 16. Cooling water, compressed air, He gas, carbon dioxide gas, and the like can be used for the refrigerant, but compressed air is injected in the present embodiment. The cooling medium injected from the cooling nozzle 16 is directed to a position slightly away from the left end of the beam spot, so as to form a cooling spot on the surface of the glass substrate A. FIG.

Moreover, the cutter wheel 18 with a periodic groove is attached to the attachment frame 15 via the lifting mechanism 17. As shown in FIG. The cutter wheel 18 is used to temporarily descend from above the glass substrate A when forming the initial crack Tr in the glass substrate A. As shown in FIG.

Fig. 2 is a schematic view of a cutter wheel with a periodic groove, Fig. 2 (a) is a front view, and Fig. 2 (b) is a side view. In the periodic grooved cutter wheel 18, the groove 18b is cut-away periodically along the blade tip 18a. (In Fig. 2, for convenience of explanation, the groove for the blade tip 18 18b) is exaggerated than the actual size). Specifically, the groove pitch is formed in the range of 20 µm to 200 µm, depending on the wheel diameter of 1 to 20 mm. Moreover, the groove depth is 2 micrometers-2500 micrometers.

By using such a cutter blade of a special blade tip, it is possible not only to form a crack penetrating deeper than a normal cutter wheel without a groove, but also to make the blade tip less slippery with respect to the substrate surface. The initial crack can be reliably formed only by rolling the distance (about 1 mm-2 mm).

Moreover, the camera 20 which can detect the alignment mark for positioning previously imprinted on the glass substrate A is mounted in the board | substrate processing apparatus LS1, and the camera 20 From the position of the detected alignment mark, the positional relationship between the position of the scribe plan line set on the board | substrate A and the rotation table 12 is calculated | required, and the falling position of the cutter wheel 18 and the irradiation position of a laser beam are It can be positioned accurately so as to be on a scribe schedule line.

Next, the processing operation procedure by the said substrate processing apparatus LS1 is demonstrated. FIG. 3 is a diagram showing a machining operation procedure of laser scribing until a scribe line is formed by the first laser irradiation, and FIG. 4 is a machining operation procedure of performing laser brake processing by the second laser irradiation. Drawing. 3 and 4 show only the main parts of FIG. 1.

First, as shown to Fig.3 (a), the glass substrate A is mounted on the turntable 12, and is fixed by the suction chuck. The alignment mark imprinted on the glass substrate A is detected by the camera 20 (FIG. 1), and based on the detection result, the scribe plan line, the rotation table 12, the slide table 2, and the base Position with (7) is concerned. Then, by operating the rotary table 12 and the slide table 2, the position is adjusted so that the blade tip direction of the cutter wheel 18 stands side by side in the direction of the scribe scheduled line.

Subsequently, as shown in FIG.3 (b), the 1st board | substrate end which tries to form the initial crack Tr in the glass substrate A by operating the pedestal 7 and moving the turntable 12 is carried out. In the vicinity of A1 and above the position spaced apart from the first substrate end A1, the cutter wheel 18 is brought.

Next, as shown in FIG.3 (c), the lift mechanism 17 is operated and the cutter wheel 18 is lowered. The blade tip is pressed against the substrate A to form an initial crack Tr. At this time, the base 7 is moved about 2 mm to drive the cutter wheel 18 on the substrate, thereby forming a stable initial crack Tr.

Subsequently, as shown in FIG. 3 (d), the lifting mechanism 17 and the turntable 12 are returned to their original positions (the positions in FIG. 3 (a)) to operate the laser device 13 to operate the laser beam. Investigate. In addition, the refrigerant is injected from the cooling nozzle 16. At this time, heating conditions, such as laser power to be irradiated, refrigerant injection amount, and cooling conditions, are set within a range where no penetration crack occurs (that is, no full cut) at the position of the initial crack Tr described later.

As in the present embodiment, the initial crack Tr is spaced apart from the substrate end (first substrate end A1) and formed at the substrate inner position, thereby causing force to tear left and right on the first substrate end A1 (full cut). Even if the force to be in the state) acts, the first substrate end A1 without initial cracking is in a state in which cracks are difficult, so that a full cut is produced compared to the case where an initial crack is formed in the substrate end A1. It's hard to be. Moreover, the process window which can select the conditions which are not full cut about heating conditions, such as the laser output to irradiate, the refrigerant injection quantity, and cooling conditions, is widened. Therefore, as setting heating conditions and cooling conditions, you may select radical conditions, ie, conditions which can form a scribe line deeper, than when the initial stage crack was formed in the board | plate edge.

Subsequently, as shown in FIG. 3E, the pedestal 7 (FIG. 1) is moved to form a beam spot of the laser beam formed on the substrate A, and the refrigerant from the cooling nozzle 16. Allow the cooling spot to be scanned along the scribe line.

By the above operation | movement, the scribe line which consists of the crack Cr of finite depth starting from the position of the initial stage crack Tr is formed in the board | substrate A. As shown in FIG. At this time, by selecting the heating condition of the laser or the cooling condition by the coolant in a range where no through crack is formed, a scribe line having a depth that has been difficult until now can be formed. At this time, the area | region in which the crack Cr is not formed exists in the board | substrate end (1st board | substrate end A1) by the side of the initial stage crack Tr of the board | substrate A.

On the other hand, at a terminal (second substrate end A2) of the scribe line of the substrate A, a region of a crack Cr1 deeper than that is locally formed as compared to the crack Cr having a finite depth formed at the center of the substrate. do. This may be attributed to the fact that the movement state of heat after heating and cooling is different in the scribe line at the center of the substrate and the scribe line at the end of the substrate. .

FIG. 5 is a photograph showing the divided surface of the scribe line, FIG. 5 (a) is the center portion of the substrate, and FIG. 5 (b) is the termination portion. In the board | substrate with a plate thickness of 2.8 mm, while the depth of crack Cr is 0.48 mm in the center part of the board | substrate, the crack Cr1 of the terminal penetrates to 1.6 mm.

As described above, it has been found that a deep crack Cr1 is formed locally at the end of the scribe line, so that the second laser irradiation is terminated (second substrate end A2) in order to perform the laser brake process using this. Scan in the reverse direction from the side.

That is, as shown in FIG. 4 (f), the laser device 13 is operated to irradiate a laser beam. The heating conditions at this time are mentioned later.

Subsequently, as shown in Fig. 4G, the pedestal 7 is moved to move the beam spot formed on the substrate A from the second substrate end A2 along the scribe line to the first substrate end A1. In the reverse direction. As a result, since the deep crack Cr1 is advanced along the scribe line, a deeper scribe line is formed to the first substrate end A1. In addition, although a region in which the crack Cr is not formed exists in the vicinity of the first substrate end A1, a deep crack can continuously proceed to the first substrate end A1 without any problem.

Here, the heating condition at the time of laser brake process is demonstrated. About heating conditions, such as a laser output, although it may be the same as the time of 1st laser irradiation, it is preferable to set as follows.

In the laser brake process, the scanning speed is set faster than the first laser irradiation, the heating time at each point on the scribe line is shortened (laser output is set high), and the surface layer of the scribe line is set to heat only for a short time. This is for forming a stress gradient for deeply penetrating the crack Cr between the substrate surface layer and the inside of the substrate.

6 is a cross-sectional view schematically showing the stress gradient which is to be formed during laser brake processing. The substrate surface layer is heated for a short time to form the heating region (H). Then, large compressive stress HR is formed in the substrate surface layer, and under the influence, tensile stress CR is generated inside the substrate. If crack Cr exists inside a board | substrate, tensile stress will concentrate on the front-end | tip of crack Cr, As a result, crack Cr will penetrate deeper.

When the heating time of the substrate surface layer is lengthened, heat is transferred to the inside of the substrate, and the temperature difference generated in the depth direction becomes small. As a result, the stress gradient in the depth direction is weakened. Therefore, in the laser brake process, in order to set the compressive stress in the substrate surface layer, the heating condition in which the tensile stress is easily formed in the substrate, and the cooling condition, the heating condition that is strongly heated within a short time is selected in a temperature range in which the substrate is not softened. It is desirable to. In addition, by cooling the refrigerant by blowing it in advance before heating, the temperature difference in the depth direction may be increased, and tensile stress may be easily generated inside the substrate.

In addition, the deep scribe line will be formed by setting the deep crack Cr1 as a starting point.

By making the deep crack Cr1 formed in the 2nd board | substrate end A2 into the start end of a laser brake process, the initial position of the crack tip which concentrates tensile stress can be made into the deep position of a board | substrate. In this state, by performing laser irradiation, a strong compressive stress is imparted to the substrate surface layer. As a result, the tensile stress is concentrated at the crack tip in the deep position, and the longer the distance from the substrate surface to the crack tip is, the greater the force (moment) trying to expand the crack acts in the direction of tearing the crack tip. Cracks penetrate deeply.

FIG. 7: is sectional drawing which showed typically the advancing state of the divided surface at the time of performing a laser brake process, with deep crack Cr1 as a starting end. With the scanning of the beam spot, as shown in Figs. 7A, 7B, and 7C, cracks Cr2 are formed by laser brake processing while maintaining the depth of deep cracks Cr1. It goes on.

As described above, by irradiating the laser beam in the reverse direction from the second substrate end side toward the first substrate end, the scribe line made of the above-described deep crack Cr2 can be formed, and the crack Cr2 Is reached to the rear surface, the substrate can be completely separated by the laser brake treatment.

The divided surface formed by this mechanism is very beautiful, and also has excellent straightness, and is in an ideal state as a processing cross section.

Further, in the above-described embodiment, the initial crack Tr was formed at a position spaced apart from the first substrate end A1 at the time of laser scribing, but was formed from the first substrate end A1 as in the prior art. It may be the case. In that case, at the time of laser scribing, since the process window of the heating conditions and cooling conditions in a 1st laser irradiation becomes narrow, the scribe line formed by the 1st laser irradiation is too much like conventionally. Although it cannot deepen, even in that case, a deeper crack Cr1 is used as a starting end by scanning the second laser irradiation from the second substrate end A2 toward the first substrate end A1. A scribe line made of (Cr2) can be formed.

In addition, in order to confirm the formation of the crack in laser scribing and the penetration of the crack in the laser brake process, the presence or absence of the crack and the depth may be detected by an optical sensor. In this case, it is good to detect the presence or the depth of a crack by making the relative movement direction back of a cooling spot into a test | inspection range at the time of laser scribing, and setting the rear movement direction direction of a beam spot as a test | inspection range during a laser brake process. Two sensors may be formed at positions respectively corresponding to the two inspection ranges, or one sensor may be formed to be movable at positions corresponding to the two inspection ranges with an air cylinder or the like.

INDUSTRIAL APPLICABILITY The present invention can be used for processing to form a deep scribe line or to completely divide a brittle material substrate such as a glass substrate.

2: slide table
7: base
12: rotating table
13: laser device
16: cooling nozzle
17 lifting mechanism
18: Cutter wheel with cycle groove
A: glass substrate (brittle material substrate)
BS: Beam Spot
CS: Cooling Spot
Cr: Crack
Cr1: deep crack
Cr2: Crack
Tr: initial crack

Claims (4)

As a processing method of a brittle material substrate which processes the said board | substrate by performing two laser irradiation along the scribe plan line from the 1st board | substrate end set to the brittle material board | substrate to the 2nd board | substrate end,
(a) an initial crack forming step of forming an initial crack on the scribe plan line near the first substrate end;
(b) the beam spot of the first laser irradiation is relatively moved from the first substrate end side to the second substrate end along the scribe scheduled line, and the substrate is heated to a softening temperature or less. A laser scribing step of forming a scribe line having a finite depth along the scribe line by using a stress gradient in a depth direction generated in the scribe line to cool by spraying a coolant to a portion immediately after the beam spot passes;
(c) the beam spot of the second laser irradiation is moved relatively from the second substrate end to the first substrate end along the scribe line in the opposite direction to the laser scribing process to infiltrate the scribe line more deeply, or A method for processing a brittle material substrate, which comprises a laser brake step of completely dividing. The method of claim 1,
The initial crack formation step of (a), wherein the initial crack is formed so as to be spaced apart from the first substrate end. The method of claim 2,
In the initial crack forming step of (a), the initial crack is formed by pressing a grooved cutter wheel with a periodic groove formed at a blade edge. 4. The method according to any one of claims 1 to 3,
In the laser brake step of (c), when the beam spot of the second laser irradiation is relatively moved in the opposite direction from the second substrate end to the first substrate end along the scribe line, the front of the beam spot passes. A processing method of a brittle material substrate which cools by injecting a coolant to a site.

Images