KR101165977B1 - Method for processing fragile material substrate - Google Patents

Abstract

Provided are a method of processing a brittle material substrate which can stably perform a process of completely dividing a substrate or forming a deeper scribe line. A laser scribing step of forming a scribe line by cooling the portion immediately after the first beam spot passes while heating the substrate by relatively moving the first beam spot by the first laser irradiation; and the second The laser beam process is performed by relatively moving the second beam spot by the laser irradiation along the scribe line to penetrate the scribe line even more deeply, or completely dividing the laser beam. It adjusts so that it may become smaller than the laser beam diameter which injects at the time of this laser scribing process, and irradiates the energy distribution of a 2nd beam spot into a top hat type rather than a 1st beam spot.

Description

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

According to the present invention, a beam spot having a substantially long axis direction is shaped on a brittle material substrate by repeatedly reflecting a laser beam with a polygon mirror rotating at a high speed, and the beam spot is set on the brittle material substrate. The invention relates to a method for processing a brittle material substrate in which cracks are formed using thermal stress by scanning along one scribe line.

More specifically, the present invention forms a scribe line composed of cracks of a finite depth by scanning the first beam spot on the brittle material substrate, and then the second beam spot. The scanning method of the present invention relates to a method for processing a brittle material substrate that penetrates deeply into the cracks of the scribe line (hereinafter, referred to as "penetration" of the cracks traveling in the depth direction) or divides completely. .

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

When the laser beam is irradiated to the polygon mirror rotating at high speed, and the laser beam reflected from the polygon mirror is guided onto the substrate, the scanning trajectory of the laser beam reflected by one mirror surface of the polygon mirror is repeatedly scanned at high speed. The entire range of the scanning trajectories of the laser beams reflected by one mirror surface is irradiated onto the substrate as if it were one beam spot. Therefore, the entire range of the scanning trajectories formed on the substrate by one mirror surface of the polygon mirror during the high speed rotation is referred to as "beam spot".

An elliptical beam spot is shaped by irradiating a laser beam with a polygon mirror and an f? Lens on a brittle material wafer, and the beam spot is scanned to ablate the substrate, thereby inclining the substrate surface. The machining surface is formed. Using this, the laser processing apparatus which vaporized the part which is going to form a groove on a semiconductor wafer in the diagonal direction (normal direction of a processing surface), and discharges it in vapor form is disclosed (patent document 1). In the processing by ablation, the processing surface is damaged because the area where the beam spot has passed melts.

On the other hand, the laser scribing process which scans the oval-shaped beam spot with respect to a glass substrate, heats a board | substrate below melting temperature (or softening temperature), produces a stress gradient, and forms a crack is also used. (See Patent Document 2, Patent Document 3, and Patent Document 4).

Generally, in laser scribing, an imaginary line (called a scribe scheduled line) to be divided in the future is set on the substrate. Then, an initial crack (trigger) is formed at the substrate end, which is the beginning of the scribing scheduled line, with a cutter wheel or the like, and the beam spot and the cooling spot (region where the refrigerant is injected) are scribed from the initial crack position. Scan along a predetermined line. At this time, as a result of the stress gradient generated based on the temperature distribution generated near the scribe scheduled line, cracks are formed.

The crack formed by the laser scribing process has a beautiful processing cross section and has excellent cross section strength. In addition, the generation of cullets can be reduced as compared with cracks caused by mechanical processing using a cutter wheel or the like.

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

By the way, in the crack formed by scanning a beam spot below melting temperature, the "finite depth crack" which does not reach the front end of a crack depth to the back surface of a board | substrate, and the crack reaches the back surface of a board | substrate, and a board | substrate is carried out at once There exists a "penetration crack" (for example, refer patent document 2) to segment.

Subsequently, the cutting line formed by the former "finite depth crack" 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.

14 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. 14 (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. 14B. 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. 14C, a stress gradient in the depth direction in which the tensile stress CR is distributed on the substrate surface side and the compressive stress HR is generated inside the substrate, whereby 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 the crack Cr is very beautiful (surface irregularities are small), and it is excellent in straightness, and it is in an ideal state as a processing cross section.

Fig. 15 is a perspective view (Fig. 15 (a)) and a plan view (Fig. 15 (b)) of a substrate which schematically show a mechanism through which a through crack is 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 the substrate can be divided (full cut) without performing a braking process, and the division by these mechanisms may be desired depending on the processing purpose. Compared with the processing cross section of one scribe line, the straightness of the processing cross section of the full cut line may be impaired, and the quality of the cross section of the full cut line (surface irregularities) is also lower than that of the scribe line described 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, beam spot shape, etc.), cooling conditions (refrigerant temperature, injection amount, injection position) Etc.), and the board thickness of the substrate.

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, when it is desired to perform the segmentation processing having excellent cross-sectional quality on a glass substrate or the like, laser scribing is performed by selecting heating conditions and cooling conditions of a mechanism in which a scribe line is formed, not a full cut line. The brake process is performed.

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 a mechanical brake process, a cullet may generate | occur | produce when a large bending moment is applied to a board | substrate. 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.

Thus, a second laser irradiation is performed along the scribe line formed by laser scribing to further penetrate the crack of a finite depth (in this case, a brake treatment again), or the crack penetrates to the back surface and divides it. Laser brake processing is performed (for example, see Patent Documents 2 to 4).

Japanese Laid-Open Patent Publication 2005-288541 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 completely divide a board | substrate by a laser brake process, it is preferable to form a deep scribe line at the time of laser scribing.

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 the conventional by laser scribing process, it is necessary to change the heating conditions and cooling conditions at the time of forming a scribe line so far. Specifically, the amount of heat generated by heating is increased to increase the laser output, or the amount of refrigerant injected during cooling is increased, and the temperature generated in the substrate is set as a radical condition where a temperature difference in the depth direction is more likely to occur. It is necessary to increase the stress gradient in the depth direction.

However, when attempting to shift to a heating condition and a cooling condition that increase the stress gradient while maintaining the processing order of conventional laser scribing, the first laser irradiation does not form a deep scribe line, and instead the crack penetrates the substrate. Discarded (the transition to the mechanism through which penetrating 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 the settable heating and cooling conditions does not exist, or even if it exists, the settable range (process window) is too 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.

In addition to the problem of shifting to a full cut line, there is also a problem in that the phenomenon of "falling ahead" easily occurs. As shown in Fig. 16, the term “preceding” means that the beam spot BS is formed when the initial crack TR formed at the start end is heated near the start end of the scribe scheduled line L by the beam spot BS. This is a phenomenon in which the crack K is formed in a direction that cannot be controlled toward the front of the beam spot starting from the heating region by. When "winding ahead" occurs, the scribe line along the scribe scheduled line L cannot be formed, and the straightness of the scribe line is significantly impaired.

In the laser scribing process of performing the first laser irradiation, when the deep scribe line is formed and the heating condition or the cooling condition is shifted to a more intense heating condition or cooling condition, such "winding over" occurs. The frequency increases.

Therefore, the present invention provides a brittle material substrate which can stably perform a process of forming a scribe line on a substrate by laser scribing and then performing a laser break treatment to completely divide the substrate or to form a deeper scribe line. An object of the present invention is to provide a processing method.

It is also an object of the present invention to provide a method for processing a substrate that can form a deep scribe line or completely divide it without causing a "winding over" phenomenon.

Moreover, it aims at providing 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.

In addition, the present invention forms a laser spot using a polygon mirror, and when the laser spot is scanned by scanning the laser spot, it is possible to adjust the energy distribution of the laser spot using the polygon mirror, thereby adjusting the energy distribution. It is an object of the present invention to provide a processing method capable of stable laser brake.

In the method of processing the brittle material substrate of the present invention made to solve the above problems, a beam spot is formed on a brittle material substrate by repeatedly reflecting a laser beam emitted from a laser light source with a polygon mirror rotating at high speed, and setting the substrate. The following procedure is performed as a processing method of a brittle material substrate which processes a board | substrate by carrying out the relative movement of this beam spot along one scribe plan line.

First, the first beam spot by the first laser irradiation is relatively moved along the scribe scheduled line to heat the substrate, and a coolant is injected by cooling to a portion immediately after the first beam spot passes, thereby providing depth. A laser scribing step is performed in which a stress gradient that changes in the direction is generated to form a scribe line consisting of cracks of finite depth. However, when the substrate is melted, processing using stress cannot be performed. Therefore, the heating temperature is always lower than the softening temperature of the substrate so that the substrate is not melted.

As a result, a stress gradient (called a first stress gradient) that changes in the depth direction occurs in the scribe plan line. The first stress gradient is a stress gradient in which tensile stress is distributed on the substrate surface side and compressive stress is distributed on the substrate inner side. Using this first stress gradient, a scribe line composed of cracks of finite depth is formed.

Subsequently, a laser brake process is performed by relatively moving the second beam spot by the second laser irradiation along the scribe line (a crack of finite depth). At this time, the laser beam diameter incident on the polygon mirror is adjusted to be smaller than the laser beam diameter incident on the laser scribe process. This adjustment may specifically reduce the beam diameter itself of a laser beam, and may provide the mechanism which adjusts a beam diameter on an optical path. By this adjustment, the ratio when the laser beam irradiated to the polygon mirror is irradiated to only one mirror surface of the polygon mirror increases, and the ratio when irradiated in the state divided into two adjacent mirror surfaces decreases. As a result, the energy distribution of the second beam spot is shortened at both ends of the energy increase and decrease, so that the entire length of the second beam spot is shorter than the entire length of the first beam spot and the energy is uniform. The area becomes an energy distribution of a long top hat type (described in detail in FIG. 11). In addition, the "top hat type energy distribution" here means the energy distribution which energy of the center part of a beam spot is substantially uniform, and energy changes in the area | region of the both ends of a beam spot.

By changing the energy distribution of the second beam spot in this manner, the amount of heat input per unit time can be increased, the surface layer of the substrate can be concentrated and heated, and a high temperature region is formed in the substrate surface layer. As a result, a stress gradient (second stress gradient) that changes in the reverse direction in the depth direction is formed from the stress gradient (first stress gradient) that changes in the depth direction during laser scribing. That is, compressive stress is generated on the surface of the substrate, and tensile stress is formed inside the substrate as a reaction thereof. The crack tip forming the scribe line is present inside the substrate, but since the tensile stress is concentrated and applied to the crack tip, the crack tip penetrates deeper and is completely broken when reaching the back surface of the substrate.

(Means and effects to solve other problems)

In the above invention, the position of the condensing optical element formed on the optical path of the laser beam between the laser light source and the polygon mirror may be changed to adjust the laser beam diameter incident on the polygon mirror.

As the condensing optical element, condensing lenses (for example, meniscus lenses) and condensing mirrors can be used.

According to this, the laser beam diameter can be adjusted only by moving the light converging optical element in parallel in the optical path direction, and the adjustment which makes the energy distribution the top hat type with the long region of the uniform energy can be easily realized.

In the above invention, in the laser brake step, the polygon mirror may be adjusted to approach the focal length of the light converging optical element.

According to this, as the laser beam diameter becomes smaller as the vicinity of the focal length approaches, the polygon mirror can be brought closer to the ideal top hat type.

In the above invention, the distance between the polygon mirror and the substrate may be adjusted simultaneously with the position of the condensing optical element.

This makes it possible to adjust the energy distribution to the top hat shape and to adjust the beam shape such as the length of the beam spot in the long direction, so that the heat input area can be adjusted together with the heat input amount per unit time. The process window can be wider.

According to the present invention, a scribe line (crack of finite depth) is formed on the substrate by a laser scribing process without a full cut line being formed and without causing a "winding over" phenomenon, and then a laser brake. The process window which can perform a process which performs a process which fully divides a board | substrate and forms a deep scribe line, and can process can be expanded, and stable processing can be implement | achieved.

Moreover, the parting process which is excellent in the cross-sectional quality of a process cross section can be performed stably. In addition, according to the present invention, when the beam spot is formed using the polygon mirror, and the laser spot is scanned by scanning the beam spot, the energy distribution of the beam spot can be adjusted using the polygon mirror. By using this, a stable laser brake can be obtained.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic block diagram of an example of the substrate processing apparatus used when implementing the substrate processing method of this invention.
FIG. 2 is a block diagram illustrating a control system of the substrate processing apparatus of FIG. 1.
3 is a diagram illustrating an example of the operation of the optical path adjusting mechanism 14.
Fig. 4 is a diagram showing the relationship between the rotation angle of the polygon mirror when the beam diameter is large, the optical path and the beam spot of the laser beam (when irradiated near the start end of one mirror surface).
Fig. 5 is a diagram showing the relationship between the rotation angle of the polygon mirror when the beam diameter is large, the optical path and the beam spot of the laser beam (when irradiated to the center of one mirror surface).
Fig. 6 is a diagram showing the relationship between the rotation angle of the polygon mirror when the beam diameter is large, the optical path and the beam spot of the laser beam (when irradiated near the end of one mirror surface).
7 shows the change over time of the cross-sectional shape of the laser beam irradiated to the mirror plane rotating at high speed when the beam diameter is small, and the energy distribution of the beam spot irradiated to the glass substrate G by the mirror plane. It is a figure which shows the relationship of.
Fig. 8 is a diagram showing the relationship between the rotation angle of the polygon mirror when the beam diameter is small, the optical path and the beam spot of the laser beam (when irradiated near the start end of one mirror surface).
Fig. 9 is a diagram showing the relationship between the rotation angle of the polygon mirror when the beam diameter is small, the optical path and the beam spot of the laser beam (when irradiated to the center of one mirror surface).
Fig. 10 is a diagram showing the relationship between the rotation angle of the polygon mirror when the beam diameter is small, the optical path and the beam spot of the laser beam (when irradiated near the end of one mirror surface).
11 shows the change over time of the cross-sectional shape of the laser beam irradiated to the mirror surface rotating at high speed, the energy distribution of the beam spot irradiated to the glass substrate G by the mirror surface, when the beam diameter is small; It is a figure which shows the relationship of.
It is sectional drawing which shows typically the stress gradient which is going to form at the time of a laser brake process.
13 is a flowchart of a processing procedure according to the substrate processing method of the present invention.
It is sectional drawing which shows typically the mechanism in which the crack of finite depth is formed.
15 is a perspective view and a plan view schematically showing a mechanism in which a full cut line is formed.
FIG. 16 is a diagram illustrating a winding phenomenon occurring at the substrate end. FIG.

Best Mode for Carrying Out the Invention [

(Device configuration)

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 laser splitting device LC1 according to an embodiment of the present invention. FIG. 2 is a block diagram showing the configuration of a control system in the laser dividing apparatus LC1 of FIG. 1.

First, based on FIG. 1, the whole structure of laser dividing apparatus LC1 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 said slide table 2 is screwed to this screw screw 5, Therefore, the slide table 2 is formed to reciprocate in the Y direction along the guide rails 3 and 4 by rotating the screw screw 5 forward and backward with a motor (not shown).

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 10a rotated by the motor 9 is screwed through the stay 10 fixed to the pedestal 7, and the screw 7a rotates forward and backward, whereby the pedestal 7 Along the guide rail 8, it reciprocates in the X direction.

On the pedestal 7, the rotary table 12 which is rotated by the rotary mechanism 11 is formed, and in this state, the glass substrate G which is a brittle material substrate of a cutting object is horizontal to this rotary table 12. Attached. The rotary mechanism 11 rotates the rotary table 12 around the vertical axis | shaft, and is formed so that it may rotate so that it may become arbitrary rotation angle with respect to a reference position. Glass substrate G is fixed to the turntable 12 by a suction chuck, for example.

Above the rotary table 12, the laser oscillator 13 and the optical path adjustment mechanism 14 are held by the attachment frame 15. As shown in FIG. The optical path adjustment mechanism 14 includes an optical path adjustment element group 14a (meniscus lens 31, reflection mirror 32, polygon mirror 33) for adjusting the optical path of the laser light emitted from the laser oscillator 13. ), A motor group 14b (motors 34 to 36) that move the position of the optical path adjusting element group 14a, and an arm group 14c that connects the optical path adjusting element group 14a and the motor group 14b. ) (Arms 37-39). The meniscus lens 31 is connected to the lifting motor 34 via the arm 37 to adjust the position in the vertical direction. In addition, the reflection mirror 32 is connected to the lifting motor 35 via the arm 38 so that the position in the up-down direction can be adjusted. Moreover, the polygon mirror 33 is connected to the lifting motor 36 via the arm 39, and it is possible to adjust the position of the up-down direction.

The laser beam emitted from the laser oscillator 13 passes through these optical path adjusting element groups 14a, whereby a beam bundle having a desired cross-sectional shape is formed and irradiated as a beam spot on the substrate G. In this embodiment, a circular laser beam is emitted, the beam diameter is adjusted by the meniscus lens 31, and scanned by the polygon mirror 33, whereby a substantially elliptical laser spot LS (Fig. 2) is formed. It is formed on glass substrate G. By adjusting the optical path adjusting element group 14a, the first beam spot used at the first laser irradiation (laser scribe process) and the second beam spot used at the second laser irradiation (laser brake process) are switched.

In addition, fine adjustment is possible by adjusting the reflection mirror 32 and the polygon mirror 33 independently at the time of adjustment, whereas the adjustment work becomes complicated. Therefore, the reflection mirror 32 and the polygon mirror 33 may be moved integrally to simplify the adjustment work. Specifically, the distance between the substrate G and the polygon mirror 33 is adjusted by moving the reflective mirror 32 and the polygon mirror 33 together, and the meniscus lens 31 is moved to the menis. The distance between the curse lens 31 and the polygon mirror 33 may be adjusted.

In the attachment frame 15, a cooling nozzle 16 is formed in proximity to the optical path adjusting mechanism 14. From this cooling nozzle 16, cooling media, such as cooling water, He gas, and a carbon dioxide gas, are sprayed on glass substrate G. As shown in FIG. The cooling medium is injected in the vicinity of the elliptic laser spot LS irradiated to the glass substrate G, and forms the cooling spot CS (FIG. 2) on the surface of the glass substrate G. As shown in FIG.

The cutter wheel 18 is attached to the attachment frame 15 via the vertical movement adjustment mechanism 17. The cutter wheel 18 is made of sintered diamond or cemented carbide and has a V-shaped ridge having a vertex on its outer circumferential surface, and the pressure contact force to the glass substrate G is vertical movement control mechanism 17. It can be adjusted finely. When using the cutter wheel 18 to form the initial crack TR (FIG. 2) on the edge of the glass substrate G only, the cutter wheel 18 is temporarily lowered while moving in the X direction.

Moreover, the pair of cameras 20 and 21 are fixed above the attachment frame 15, and the positioning marker which is carved by the board | substrate G can be projected.

Next, a control system is demonstrated based on FIG. The laser dividing apparatus LC1 is provided with the control part 50 which performs various processes by the control parameter and program (software) which were stored in the memory, and a CPU. This control part 50 is a table drive part 51 which drives the motor (motor 9 etc.) for positioning and movement of the slide table 2, the pedestal 7, and the rotation table 12, and a laser. The laser drive part 52 which irradiates (the laser light source drive part 52a which drives the laser oscillator 13), and the optical path adjustment mechanism drive part 52b which drives the motor group 14b for the optical path adjustment element group 14a is included. Glass substrate G by the nozzle drive part 53 which drives the opening / closing valve (not shown) which controls refrigerant | coolant injection by the cooling nozzle 16, the cutter wheel 18, and the up-down movement control mechanism 17. Each drive system of the camera drive part 55 which illuminates the positioning marker imprinted on the board | substrate G is controlled by the cutter drive part 54 which forms initial stage cracks), and the cameras 20 and 21. In addition, the control unit 50 is connected to an input unit 56 composed of a keyboard, a mouse, and the like, and a display unit 57 for performing various types of display on the display screen, so that necessary information is displayed on the screen, and necessary commands and settings are made. You can enter.

Moreover, the control part 50 comprehensively combines the table drive part 51, the laser drive part 52 (laser light source drive part 52a, the optical path adjustment mechanism drive part 52b), the nozzle drive part 53, and the cutter drive part 54 comprehensively. The processing control part 58 which drives and processes the glass substrate G is provided, The laser processing according to the order of 1st laser irradiation, cooling, and 2nd laser irradiation is performed by this processing control part 58. FIG. .

Specifically, the processing control part 58 first controls the cutter drive part 54 and the table drive part 51, moves the board | substrate G in the state which lowered the cutter wheel 18, and accordingly, an initial crack ( The process of forming TR) is performed. Subsequently, the table driving unit 51, the laser driving unit 52, and the nozzle driving unit 53 are controlled to irradiate a laser beam (first beam spot) and move the substrate G in a state where a refrigerant is injected. As a result, the first laser irradiation and cooling are performed to form a scribe line formed of a crack having a finite depth on the substrate. Subsequently, the table driving unit 51 and the laser driving unit 52 are controlled to move the substrate G in a state where the laser beam (second beam spot) is irradiated. As a result, a second laser irradiation is performed to infiltrate the crack (or to perform a complete segmentation).

(Optical path adjustment operation)

Next, the optical path adjustment performed by the processing control part 58 controlling the optical path adjustment mechanism 14 (optical path adjustment element group 14a, motor group 14b, arm group 14c) is demonstrated.

3 is a view showing an example of the operation of the optical path adjusting mechanism 14. Specifically, the beam diameter irradiated to the mirror surface of the polygon mirror 33 is changed by vertical movement of the meniscus lens 31. FIG. Is a diagram illustrating an operation of changing the energy distribution of the beam spot irradiated onto the substrate G. FIG.

The advancing direction of the laser beam LB0 of the circular cross section emitted from the laser light source 13 is directed perpendicularly downward, and the laser beam LB0 is incident on the meniscus lens 31. The laser beam LB1 passing through the meniscus lens 31 is further focused in the vertical direction while being focused, and is incident on the reflection mirror 32. At this time, the angle of incidence of the reflective mirror 32 is incident on the reflective surface of the reflective mirror 32 and the attachment angle of the reflective mirror 32 is adjusted so as to be emitted at the reflective angle of 45 degrees, and the laser beam reflected by the reflective mirror 32 ( LB2) advances in a horizontal direction.

The laser beam LB2 traveling in the horizontal direction is incident on the polygon mirror 33 during rotation. At this time, the beam diameter irradiated to the mirror surface of the polygon mirror changes according to the distance between the meniscus lens 31 and the polygon mirror 33.

4-6 is a figure which shows the relationship between the rotation angle of a polygon mirror, the optical path of a laser beam, and a beam spot when the beam diameter irradiated to the mirror surface of the polygon mirror 33 is comparatively large.

The beam diameter in this state causes the meniscus lens 31 to approach the reflection mirror 32 so that the focus of the meniscus lens 31 is on the substrate G side than the mirror surface of the polygon mirror 33. Realized when adjusted. The beam diameter in this state is used during the laser scribing step.

In Fig. 4A, attention is paid to two mirror surfaces M0 and M1 in the polygon mirror 33 that are rotating clockwise. The mirror surface M0 is the mirror surface to which the laser beam LB2 was irradiated until just before. When the rotation is advanced and the irradiation of the laser beam LB2 to the mirror plane M0 is finished, the laser beam LB2 is terminated at the end of the mirror plane M0 and the start of the next mirror plane M1. Is divided and irradiated simultaneously. FIG. 4C is a diagram showing a cross-sectional shape of the laser beam LB2 irradiated to the mirror surface M0. 4D is a diagram showing a cross-sectional shape of the laser beam LB2 irradiated to the mirror surface M1.

According to the area ratio of the cross section of the divided laser beam, the energy of the laser beam irradiated to the mirror surfaces M0 and M1 is distributed. At this time, the laser beam LB3a reflected by the mirror surface M0 side irradiates the left end part of the position of the beam spot LS1 of the glass substrate G, and provides energy to this part. On the other hand, the laser beam LB3b reflected from the mirror surface M1 side irradiates the right end portion of the position of the beam spot LS1, thereby applying energy to this portion.

4B is an energy distribution irradiated to the position of the beam spot LS1 of the substrate G. As shown in FIG. That is, since the radiation is divided into laser beams LB3a and LB3b, the energy applied to the substrate G is also divided into two, and both ends of the beam spot LS1 are heated with energy corresponding to the split ratio, respectively.

In FIG. 5A, the rotation is further performed, and the laser beam LB2 is irradiated to the center portion of the mirror surface M1. At this time, the laser beam LB2 of circular cross section is irradiated to only one mirror surface M1. 5C is a diagram showing a cross-sectional shape of the laser beam LB2 irradiated to the mirror surface M1. The beam of the circular cross section which the laser beam LB2 has irradiated as it is. At this time, the laser beam LB3c reflected from the mirror surface M1 irradiates the center of the position of the beam spot LS1, and gives total energy to this part.

5B is an energy distribution irradiated to the position of the beam spot LS1 of the substrate G. As shown in FIG. Energy is applied to the central portion of the position of the beam spot LS1, and this portion is heated intensively.

FIG. 6 further shows that rotation is performed, and the laser beam LB2 is divided and irradiated at the same time to the end of the mirror surface M1 and the start of the next mirror surface M2. FIG. 6C is a diagram showing a cross-sectional shape of the laser beam LB2 irradiated to the mirror surface M1. 6D is a diagram showing a cross-sectional shape of the laser beam LB2 irradiated to the mirror surface M2.

As in the case of FIG. 4, the energy of the laser beam irradiated to the mirror surfaces M1 and M2 is distributed according to the area ratio of the cross section of the divided laser beam. At this time, the laser beam LB3d reflected by the mirror surface M1 side irradiates the left end part of the position of the beam spot LS1 of the glass substrate G, and provides energy to this part. The laser beam LB3e reflected at the mirror surface M2 side irradiates the right end portion of the position of the beam spot LS1 to impart energy to this portion.

FIG. 6B is an energy distribution irradiated to the position of the beam spot LS1 of the substrate G. FIG. The energy irradiated to the substrate G is divided into two, and both ends of the beam spot LS1 are heated with energy corresponding to the split ratio, respectively.

The laser irradiation from FIGS. 4 to 6 is repeated by the polygon mirror 33 which rotates at high speed, whereby the energy distributions shown in FIGS. 4 (b), 5 (b) and 6 (b) are added together. Beam spot LS1 having an energy distribution is formed.

7 shows a change over time of the cross-sectional shape of the laser beam LB2 irradiated to the mirror plane M1 that rotates at high speed, and the beam spot LS1 irradiated to the glass substrate G by the mirror plane M1. It is a figure which shows the relationship with an energy distribution.

As shown to Fig.7 (a), the cross section of the laser beam LB2 irradiated to the mirror surface M1 changes as rotation progresses.

That is, the cross-sectional shape of the laser beam LB2 irradiated to the mirror surface M1 in the period in which the start end (boundary to the mirror surface M0) of the mirror surface M1 passes through the irradiation range of the laser beam LB2. Is a shape in which a part of the circular cross section is missing, and the cross sectional area gradually increases during this time. Thereafter, the cross-sectional shape of the laser beam LB2 irradiated to the mirror surface M1 becomes a circular cross section, and the end of the mirror surface M1 (the boundary with the mirror surface M2) is formed of the laser beam LB2. The circular cross section continues until it enters the irradiation range. And in the period in which the end of the mirror surface M1 passes the irradiation range of the laser beam LB2, the cross-sectional shape of the laser beam LB2 irradiated to the mirror surface M1 again lacks a part of the circular cross section. The cross-sectional shape is obtained, and the cross-sectional area gradually decreases.

In response to such a change in the cross-sectional area, the energy distribution of the beam spot LS1 formed on the substrate G by the mirror surface M1 changes. The energy distribution is shown in Fig. 7 (b). The energy distribution of the beam spot LS1 is an energy distribution in which the energy of the center portion is uniform (top hat type) and both ends thereof change gently. As for the width | variety of the gentle part of both ends, the laser beam reflected by the mirror surface M1 is reflected on the board | substrate G in the period which the beginning or end of the mirror surface M1 passes through the irradiation range of the laser beam LB2. It corresponds to the range investigated in. Therefore, as the beam diameter of the laser beam LB2 increases, the width of the portion where the energy distribution of both ends of the beam spot LS1 changes slowly becomes wider. And with each mirror surface of the rotating polygon mirror 33, irradiation with the energy distribution of FIG. 7 (b) is repeated.

Next, the case where the beam diameter irradiated to the mirror surface is small is demonstrated. 8-10 is a figure which shows the relationship between the rotation angle of a polygon mirror, the optical path of a laser beam, and a beam spot when the beam diameter of the laser beam LB2 irradiated to a mirror surface is comparatively small.

The beam diameter in this state is realized when the position of the meniscus lens 31 is adjusted so that the focal point of the meniscus lens 31 is in the vicinity of the mirror surface M1 of the polygon mirror 33. The beam diameter in this state is used during the laser brake process.

In FIG. 8A, similarly to FIG. 4A, attention is paid to two mirror surfaces M0 and M1 in the polygon mirror 33 that are rotating clockwise. The mirror surface M0 is the mirror surface to which the laser beam LB2 was irradiated until just before. When the rotation is advanced and the irradiation of the laser beam LB2 to the mirror plane M0 is finished, the laser beam LB2 is terminated at the end of the mirror plane M0 and the start of the next mirror plane M1. Is divided and irradiated simultaneously. FIG. 8C is a diagram showing a cross-sectional shape of the laser beam LB2 irradiated to the mirror surface M0. 8D is a cross-sectional shape of the laser beam LB2 irradiated to the mirror surface M1. Since the beam diameter is small, the range in which the two mirror surfaces M0 and M1 are irradiated simultaneously (the range from the beginning to the end to the beam diameter) is narrower than in the case of FIG.

The energy of the laser beam irradiated to the mirror surfaces M0 and M1 is distributed according to the area ratio of the divided beam, similarly to FIG. At this time, the laser beam LB3a reflected by the mirror surface M0 side irradiates the left end part of the position of the beam spot LS1 of the glass substrate G, and provides energy to this part. On the other hand, the laser beam LB3b reflected by the mirror surface M1 side irradiates the right end part of the position of the beam spot LS1, and gives energy to this part.

8B is an energy distribution irradiated to the position of the beam spot LS1 of the substrate G. As shown in FIG. That is, since the radiation is divided into the laser beams LB3a and LB3b, the energy irradiated to the substrate G is also divided into two, and both ends of the beam spot LS1 are heated with energy corresponding to the split ratio, respectively.

In FIG. 9A, the rotation is further progressed so that the laser beam LB2 is irradiated to the center portion of the mirror surface M1.

At this time, the laser beam LB2 of circular cross section is irradiated to only one mirror surface M1. FIG. 9C is a diagram showing a cross-sectional shape of the laser beam LB2 irradiated to the mirror surface M1. The beam of the circular cross section which the laser beam LB2 has irradiated as it is. At this time, the laser beam LB3c reflected from the mirror surface M1 irradiates the center of the position of the beam spot LS1, and gives total energy to this part.

FIG. 9B is an energy distribution irradiated to the position of the beam spot LS1 of the substrate G at this time. Energy is applied to the central portion of the position of the beam spot LS1, and this portion is heated intensively.

10 is further rotated, and the laser beam LB2 is divided and irradiated simultaneously at the end of the mirror surface M1 and the start of the next mirror surface M2. 10C is a diagram showing a cross-sectional shape of the laser beam LB2 irradiated to the mirror surface M1. 10 (d) is a figure which shows the cross-sectional shape of the laser beam LB2 irradiated to the mirror surface M2.

As in FIG. 6, the energy of the laser beam irradiated to the mirror surfaces M1 and M2 is distributed according to the area ratio of the cross section of the divided laser beam. At this time, the laser beam LB3d reflected by the mirror surface M1 side irradiates the left end part of the position of the beam spot LS1 of the glass substrate G, and provides energy to this part. The laser beam LB3e reflected at the mirror surface M2 side irradiates the right end portion of the position of the beam spot LS1 to impart energy to this portion.

10 (b) is an energy distribution irradiated at the position of the beam spot LS1 of the substrate G at this time. The energy irradiated to the substrate G is divided into two, and both ends of the beam spot LS1 are heated with energy corresponding to the split ratio, respectively.

Then, the laser irradiation from Figs. 8 to 10 is repeated by the polygon mirror 33 rotating at high speed, so that the energy distribution shown in Figs. 8 (b), 9 (b) and 10 (b) is added and summed. The beam spot LS1 having a distribution is formed.

FIG. 11 shows the change over time of the cross-sectional shape of the laser beam LB2 irradiated to the mirror plane M1 rotating at high speed, and the beam spot LS1 irradiated to the glass substrate G by the mirror plane M1. It is a figure which shows the relationship with an energy distribution.

Since the beam diameter of the laser beam LB2 irradiated to the mirror surface M1 is small, as shown in FIG. 11 (a), the cross-sectional area to be irradiated is generally smaller than the case where the beam diameter shown in FIG. 7 (a) is large. However, energy density is increasing. 11 (a), the cross section of the laser beam LB2 irradiated to the mirror surface M1 changes as rotation progresses. That is, similarly to FIG. 7A, a period during which the start end of the mirror surface M1 (the boundary with the mirror surface M0) passes through the irradiation range of the laser beam LB2, and the mirror surface M1 In the period in which the terminal (boundary with the mirror surface M2) passes the irradiation range of the laser beam LB2, the cross section of the laser beam LB2 irradiated to the mirror surface M1 lacks a part of the circular cross section. The cross sectional shape is increased, and the cross sectional area increases or decreases within this range. In the meantime, the cross section of the laser beam LB2 irradiated to the mirror surface M1 becomes a circular cross section about the period in which the whole irradiation range of the laser beam LB2 is irradiated to the mirror surface M1.

Since the beam diameter of the laser beam LB2 is small, the width of the range in which the cross-sectional area of the laser beam LB2 irradiated to the mirror surface M1 is changed in the vicinity of the start end and the end of the mirror surface M1 is shown in FIG. Compared with a), it becomes narrower, and the cross sectional area rapidly increases or decreases. In response to this change in cross-sectional area, the energy distribution of the beam spot LS1 formed on the substrate G by the mirror surface M1 changes. The energy distribution of the beam spot LS1 at this time is shown in Fig. 11B. In addition, for comparison, the energy distribution when the beam diameter is small is shown by a solid line, and the energy distribution (energy distribution of FIG. 7 (b)) when the beam diameter is large is shown by a dashed-dotted line.

As the beam diameter of the laser beam LB2 to be irradiated becomes smaller, the energy distribution of the beam spot LS1 becomes shorter in the regions at both ends where the energy changes, and the length of the entire beam spot LS1 becomes shorter, The area of the central portion where the shape is uniform is a long top hat-shaped energy distribution.

Irradiation is repeated to the beam spot LS1 which has the same energy distribution as the mirror surface M1 by each mirror surface of the rotating polygon mirror 33.

In this way, the energy distribution of the beam spot can be adjusted only by adjusting the height of the meniscus lens 31.

In addition, although the energy distribution of the beam spot irradiated to the board | substrate G can be adjusted by changing the height of the meniscus lens 31, the length of the whole beam spot will also change at that time.

Therefore, when the long axis length of the beam spot is not to be changed for each step, or on the contrary, when the long axis length is to be shortened in the laser brake step, the meniscus lens 31 and the polygon mirror 33 are used. At the same time, the polygon mirror 33 and the reflection mirror 32 are integrally moved to adjust the distance to the substrate G, and the long axis length is also adjusted.

As a result, a beam spot shape is desired, and heating is performed with a desired energy distribution.

In the laser brake process, a larger heat input amount can be given in a short time by irradiating a beam spot having a long hat-shaped energy distribution in a region in which the energy is uniform.

12 is a cross-sectional view schematically showing a stress gradient to be formed during a laser brake process according to the machining method of the present invention. The beam spot is a top hat-shaped energy distribution, concentrated and heated in a short time from the substrate surface layer 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 the crack Cr generated by the laser scribing process immediately before exists in the substrate, the tensile stress is concentrated at the tip of the crack Cr, and as a result, the crack Cr penetrates more deeply. In addition, when the crack Cr reaches to the rear surface, it is completely divided.

(Processing sequence)

Next, the processing procedure at the time of dividing the board | substrate G using the processing apparatus LC1 is demonstrated. 13 is a flowchart of a processing procedure.

First, the substrate G is placed on the rotary table 12 and fixed by a suction chuck. The rotary table 12 is moved below the cameras 20 and 21, and alignment marks (not shown) imprinted on the glass substrate A are detected by the cameras 20 and 21. Based on the detection result, the relationship between the scribe scheduled line, the position of the rotation table 12, the slide table 2, and the pedestal 7 is stored. Then, the rotary table 12 and the slide table 2 are operated so that the blade tip direction of the cutter wheel 18 stands side by side in the direction of the scribe scheduled line and the blade tip comes near the position where the initial crack is formed. (S101). The position at this time is stored as a machining start position.

Next, the lifting mechanism 17 is operated to lower the cutter wheel 18.

The rotary table 12 (base 7) is moved to press-contact the substrate end cutter wheel 18. As a result, an initial crack TR is formed. When the initial crack TR is formed, the lifting mechanism 17 is operated to raise the cutter wheel 18 (S102).

Subsequently, the substrate G is returned to the processing start position, and the laser device 13 is operated to irradiate the first laser beam. At this time, the position of the meniscus lens 31 is adjusted to enter the mirror surface of the polygon mirror 31 with a relatively large beam diameter (see FIGS. 4 to 7). Thereby, the energy distribution of the beam spot formed in the board | substrate G is set to the energy distribution of the state which rises gently. In addition, a coolant is injected from the cooling nozzle 16. In this state, the rotary table 12 (base 7) is moved to scan the beam spot and the cooling spot along the scribe scheduled line, thereby forming a scribe line (S103).

Subsequently, the substrate G is returned to the processing start position and the second laser beam is irradiated. At this time, the position of the meniscus lens 31 is farther from the reflecting mirror 32 than in the first irradiation, and the beam diameter incident on the mirror surface of the polygon mirror 33 is reduced (Figs. 8 to 11). Reference). Thereby, the energy distribution of the beam spot formed in the board | substrate G rises steeply, and is made into the top hat type energy distribution from the 1st time. Although the cooling nozzle 16 may continue spraying, since it is not necessarily required, it stops here. In this state, the rotary table 12 (base 7) is moved to scan a beam spot having a top hat-shaped energy distribution along the scribe line formed by the last scan. Thereby, when the crack which forms the scribe line penetrates deeply and reaches | attains the back surface of a board | substrate, it fully divides (S104).

The scribe line formed in this way is a very excellent process cross section, and cross-sectional strength also becomes strong.

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: pedestal
12: rotating table
13: laser device
16: cooling nozzle
17 lifting mechanism
18: cutter wheel
31: meniscus lens
32: reflective mirror
33: polygon mirror
G: glass substrate (brittle material substrate)
Cr: Crack
Tr: initial crack

Claims (4)

The substrate is processed by repeatedly reflecting a laser beam emitted from a laser light source with a polygon mirror rotating at a high speed so that a beam spot is formed on a brittle material substrate, and moving the beam spot along a predetermined scribe line set on the substrate. As a processing method of a brittle material substrate to
The stress gradient changes in the depth direction by relatively moving the first beam spot by the first laser irradiation along the scribe scheduled line to heat the substrate and cooling the portion immediately after the first beam spot passes. A scribe process for generating a scribe line having a finite depth by
And a laser brake process in which the second beam spot by the second laser irradiation is relatively moved along the scribe line, so as to penetrate the scribe line even more deeply or completely divide it.
A method for processing a brittle material substrate in which the laser beam diameter incident on the polygon mirror during the laser brake process is adjusted to be smaller than the laser beam diameter incident on the laser scribe process. The method of claim 1,
A method for processing a brittle material substrate, in which a laser beam diameter incident on a polygon mirror is adjusted by changing a position of a light converging optical element formed on an optical path of a laser beam between a laser light source and a polygon mirror. The method of claim 2,
A method of processing a brittle material substrate, the laser brake step of adjusting to bring the polygon mirror near the focal position of the light converging optical element. The method according to claim 2 or 3,
A processing method of a brittle material substrate which simultaneously adjusts the distance between the polygon mirror and the substrate together with the position of the condensing optical element.

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