KR20100090788A - Method for forming cracks on substrate made of brittle material - Google Patents

Abstract

A crack forming method of a brittle material substrate capable of reliably stopping a second crack at an intersection with a first crack is provided. A first crack is formed by the first laser scribing process, and then a frictional coefficient lowering agent that lowers the coefficient of friction is attached to the crack of the first crack, and then the second crack is subjected to the first crack by the second laser scribe process. It forms in the direction which intersects with the 1st crack, and stops advancing of a 2nd crack at the intersection with a 1st crack.

Description

Crack formation method of brittle material substrate {METHOD FOR FORMING CRACKS ON SUBSTRATE MADE OF BRITTLE MATERIAL}

The present invention relates to a method of forming a crack in a brittle material substrate by laser scribing, and more particularly, after forming the first crack, the second crack crossing the first crack to the intersection with the first crack It relates to a method of forming.

Here, the term "laser scribing" refers to forming a beam spot by irradiating a substrate with a laser beam, causing the beam spot to move relative to the substrate, and locally heating the substrate at a temperature below the softening point, and then beam spot. The process of forming a crack using the thermal stress which generate | occur | produced by cooling the said board | substrate along this trajectory which passes.

In addition, "crack" means the linear crack formed in advance in the position to divide | segment on a board | substrate before performing the brake process which completely divides a board | substrate. The crack is composed of cracks that do not reach the rear surface of the substrate, and by performing a braking process giving a bending moment in the thickness direction along the crack, the crack is advanced in the substrate thickness direction and completely at the stage where the crack tip reaches the rear surface. It becomes a segmented dividing line.

In addition to the glass substrate, the "brittle material" includes materials such as ceramics, single crystal silicon, semiconductor wafers, and sapphire.

Brittle material substrates, such as glass substrates, are used for various products by dividing into suitable sizes and shapes.

As a method of dividing a brittle material substrate, the method of dividing by performing laser scribing process which forms a crack by laser heating and cooling immediately after heating, and the brake process which apply a bending moment along the crack formed by laser scribing process is put to practical use. It is. By dividing by laser scribing and brake processing, a dividing surface of excellent quality can be obtained.

Laser scribing is sometimes used to form a plurality of straight cracks that cross each other on a substrate (called a cross scribe). For example, when a large number of small rectangular substrates to be products are cut out from large substrates, a crosscut for dividing the substrates vertically and horizontally is performed, and cross scribing by laser scribing is performed.

In general, in laser scribing, in order to narrow the processing width and increase the heating efficiency, the shape of the beam spot is a shape having a long axis such as an ellipse or an oval shape, and the long axis direction is directed in the scanning direction. Moreover, the cooling area | region (referred to as a cooling spot) which performs cooling immediately after heating is made to move following a beam spot (refer patent document 1).

Moreover, in laser scribing, it is disclosed to improve the cutting speed of a substrate by using a liquid refrigerant rather than a gas refrigerant when the refrigerant is injected and cooled immediately after heating (see Patent Document 2).

According to this, it is preferable to use water (pure water) as a liquid refrigerant for a rapidly heated substrate, and by using a liquid refrigerant in which water and ethanol, ethylene glycol, methanol, acetone, and a surfactant are mixed with water, It is disclosed that cutting can be performed at a high cutting speed as compared with the use of a refrigerant having physical properties of gas. In addition, when silicon oil (specific heat is as small as the freon gas) that is a refrigerant having a physical property of gas is used, the cutting speed is lowered, which is undesirable as a refrigerant.

On the other hand, the process which cuts out a glass substrate along a closed curve is also performed. For example, in the process of manufacturing a circular solar cell apparatus, a plurality of circular crack outer periphery lines (circular solar cell apparatuses are formed inside the crack outer periphery) which are arranged at intervals on a large rectangular substrate are formed and adjacent to each other. The method of processing a circular substrate by forming a linear crack between the circular crack outer periphery and between the outer periphery of a large substrate and the circular crack outer periphery is disclosed (refer patent document 3).

According to this, a circular crack outer periphery is formed using a CO ₂ laser. Subsequently, on the circular substrate (solar cell device), the beam spot of the CO ₂ laser is blocked while scanning the CO ₂ laser in a straight line, and the linear crack leading to the crack outer line which comes close to the outer periphery of the large substrate. Is formed, and linear cracks are formed between adjacent crack outer periphery lines. Through the above steps, the circular substrate can be easily separated.

Japanese Patent Publication Hei 8-509947 Japanese Patent Application Laid-Open No. 2002-346995 Japanese Patent Application Laid-Open No. 2002-87836

(Initiation of invention)

(Tasks to be solved by the invention)

FIG. 1: is a schematic diagram which shows the typical processing procedure at the time of cutting out the circular member 10 from the rectangular glass substrate G using laser scribing. As shown in Fig. 1 (a), the circular cracks R-1 forming the outer circumference of the circular member 10 are formed, and a plurality of straight cracks X-1, X-2, Y-1, Y-2) is formed. This straight crack is called "cutting off", and the necessary number is formed in order to easily separate the circular member 10.

In this case, as shown in Fig. 1 (b), the order of processing is shown by the original numeral, the circular crack R-1 (first crack) is first formed, and then the position where the circular crack R-1 intersects. Each straight crack (X-1, Y-1, X-2, Y-2) (second crack) is formed.

At this time, cracks are formed in the vicinity of the boundary between the heating zone (beam spot) and the cooling zone (cooling spot), and the position of crack generation is slightly changed by a delicate balance between the heating zone and the cooling zone. In addition, the position of crack generation also changes due to the slight change in the stress distribution depending on the internal state of the substrate. Therefore, it is very difficult to stop the straight crack accurately at the intersection with the circular crack. As a result, as shown in Fig. 1 (c), the stop position of the crack is shifted, and the straight cracks X-1, Y-1, X-2 progress beyond the intersection with the circular crack, or the straight crack ( Y-1) may not reach the circular crack in some cases.

As one method for preventing such a problem, as described in Patent Document 3, the beam spot is blocked on the circular member 10, and when a straight crack is formed, part of the beam spot is formed. Even if the circular member 10 is reached beyond the intersection, it may be considered that the circular member 10 itself is not directly heated.

However, when this method is adopted, it is necessary to form a laser shielding film on the circular member 10 in advance, or to attach the circularly formed crack member while positioning the mask member on the circular member 10 after forming the circular crack. . In the former case, after forming a linear crack, the process of removing a film is needed. In the latter case, a positioning process is required, and both of them increase the process and require a lot of hands.

In addition, even when the circular member 10 itself is not directly heated by, for example, film formation or attachment of a mask member, tensile stress generated in the rear cooling zone (cooling spot) is transmitted to the front, and the tip of the straight crack is The phenomenon which advances beyond the intersection with a circular crack (it mentions later in detail) may arise, and a linear crack could not be stopped reliably.

The same problem occurs even when performing a linear laser scribing process. FIG. 2: is a schematic diagram which shows the typical processing procedure at the time of cut | disconnecting the some strip member 11 from the glass substrate G using laser scribing. In the case where the end portion 12 is formed by the relationship between the size of the glass substrate G and the size of the strip member 11, it is desirable to effectively use the end portion 12 for other purposes. At that time, as shown to Fig.2 (a), with respect to glass substrate G, a plurality of linear 1st cracks X-1 in a 1st direction and a 2nd direction orthogonal to a 1st direction Second cracks Y-1 to Y-5 are formed.

In this case, as shown in FIG. 2 (b), the processing order is represented by the original number, the first crack X-1 is first formed, and then the second cracks Y-1 to Y-5 are firstly formed. It is formed to a position intersecting the crack (X-1).

At this time, it is very difficult to accurately stop the tip of the second cracks Y-1 to Y-5 at the intersection with the first crack X-1. As a result, as shown in FIG.2 (c), the stop position of 2nd cracks Y-1 to Y-4 is displaced, and it advances beyond the intersection with 1st crack X-1, or 2nd The crack Y-5 does not reach or cross the intersection with the first crack.

Therefore, the present invention reliably forms the second crack when forming the first crack by using laser scribing and subsequently forming the second crack up to an intersection point with the first crack in the direction crossing the first crack. It is an object of the present invention to provide a crack formation method for a brittle material substrate that can be stopped at an intersection point.

In the crack formation method of this invention performed in order to solve the said subject, a 1st crack is formed by a 1st laser scribe process. Subsequently, a frictional modifier for lowering the frictional coefficient is attached to the crack of the first crack, and then the second crack is formed to the intersection with the first crack in the direction intersecting the first crack by the second laser scribe process. .

In this manner, after the first crack is formed, by attaching a frictional coefficient lowering agent in the crack of the first crack, the surfaces on both sides slide in the crack of the first crack. In this state, when the second laser scribing is performed, when the second crack reaches an intersection point with the first crack, the crack of the second crack advances to the intersection point in front of the intersection point, but the crack of the first crack at the intersection point. If they cross, the direction in which the crack of the second crack spreads by the tensile stress coincides with the direction in which the crack surface of the first crack slips, so that the progress of the crack of the second crack is interrupted due to the slipping action. As a result, the progress of the crack of the second crack at the intersection point is stopped. Thereafter, even if some heating or cooling is performed in front of the intersection point, the second crack does not advance forward unless an initial crack is formed in this portion.

According to the present invention, by attaching a friction coefficient lowering agent that lowers the friction coefficient in the crack of the first crack, the surfaces on both sides of the crack slide in the crack, so that the progress of the second crack is at the intersection with the first crack. It can stop and can reliably stop a 2nd crack.

(Means and effects to solve other problems)

It is preferable that a friction coefficient lowering agent contains lubricating oil. It is particularly desirable to contain silicone oil.

The friction coefficient lowering agent may be any material capable of lowering the friction coefficient on both sides of the crack in the crack of the first crack, for example, by containing a lubricant. Preferably, when the silicone oil is suitably contained, it can be used as a friction coefficient lowering agent.

There are many kinds of silicone oils here, but considering water solubility (when sprayed with water as a refrigerant), permeability (easiness of penetration into cracks), lubricity (easily lowering friction coefficient), it is easy to enter cracks and friction coefficient It is more preferable to select a material which is easy to fall. Specifically, among the silicones, a modified silicone oil having improved lubricity is preferable.

In materials other than lubricating oils, such as silicone oil, the material which has an alkyl group, specifically, the material which changed alkyl alcohol, alkyl ether, and fatty acid alkyl ester into the solution by alcohol addition can be used as a friction coefficient lowering agent. . Especially, if the material which has an alkyl group is an alkyl alcohol, alkyl ether, fatty acid alkyl ester which has a C1-C30 linear or branched alkyl group, it is excellent as a friction coefficient lowering agent, and it is preferable.

The friction coefficient lowering agent may be sprayed together with the refrigerant when the substrate is cooled in the first laser scribing process.

In laser scribing, a large tensile stress acts upon cooling after heating and immediately after cooling, and cracks spread, so that the coefficient of friction lowering agent can be reliably attached to the cracks by spraying with a refrigerant when cooling the substrate. In addition, since it can be attached at the same time as the refrigerant injection, there is no need to add a new process.

You may use water containing silicone oil as a refrigerant.

Refrigerants such as water (steam) and alcohol, which have been conventionally injected with nitrogen gas and compressed air as a coolant, do not function alone as a friction coefficient lowering agent. By containing silicone oil in these liquids, it can use as a friction coefficient lowering agent which can be sprayed.

The friction coefficient lowering agent may be applied or sprayed near the intersection immediately after cooling the substrate in the first laser scribing process.

Immediately after cooling, by applying or spraying separately from the coolant, the friction coefficient lowering agent can be attached only to the required intersection point in the entire first crack. Thereby, the usage-amount of a friction coefficient lowering agent can be reduced, and it can suppress that a friction coefficient lowering agent adheres to an unnecessary part.

The schematic diagram which shows the typical processing procedure at the time of dipping a closed curve by laser scribe processing in FIG.
2 is a schematic diagram showing a typical processing procedure when cutting a plurality of strip members by laser scribing.
3 is a diagram illustrating a state of a glass substrate during laser scribing.
4 is a cross-sectional view showing a state of occurrence of cracks at respective positions on a parting line.
The figure which shows each process of the crack formation method which is one Embodiment of this invention.
FIG. 6 is a diagram showing a state where the tip of the cooling spot CS has reached the first crack. FIG.

(The best mode for carrying out the invention)

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of this invention is described based on drawing. For convenience of explanation, the cracks formed by general laser scribing will first be described.

3: is a figure which shows the state of the glass substrate G during a laser scribing process, FIG. 3 (a) is a perspective view, FIG. 3 (b) is the top view which expanded the part of the substrate surface. FIG. 3 (c) is a diagram illustrating the respective cross-sectional positions of FIG. 4. 4 is sectional drawing which shows the generation state of the crack of the position shown to FIG. 3 (c).

The division scheduled line L0 is defined on the glass substrate G, the laser beam is irradiated to form an elliptical beam spot BS, and the long axis direction thereof is scanned toward the division scheduled line L0. Further, a cooling spot CS is formed by injecting a refrigerant (for example, compressed air containing water) from the nozzle (not shown) to the rear of the beam spot BS, and scanning the beam spot BS to follow the beam spot BS. do.

Specifically, the position of the laser beam which forms the beam spot BS and the nozzle which forms the cooling spot CS is fixed, and the board | substrate G is divided along the front line direction along the planned line L0 (FIG. Drawing). Middle beam direction), the beam spot BS and the cooling spot CS are scanned from the initial crack TR along the direction of the division line L0.

At this time, the compressive stress and the tensile stress occurring in the vicinity of the substrate surface are shown in Fig. 3 (b). In the figure, the magnitude of the compressive stress is indicated by a broken line arrow, and the magnitude of the tensile stress is indicated by a solid arrow.

As the beam spot BS passes, the compressive stress becomes stronger. Subsequently, when the cooling spot CS passes immediately after the beam spot BS, it is reversed in one step from the compressive stress to the tensile stress. After that, the tensile stress is gradually relaxed, and the heat inside is conducted to the surface and is reversed by a weak compressive force, and the crack ends.

Fig. 4A is a view showing a cross section A-A '(see Fig. 3 (c), which is the same for each cross section described below) immediately after the beam spot BS passes. Since the compressive stress was working, no crack occurred. Fig. 4B is a diagram showing a cross section BB ′ 'through which the cooling spot CS has passed and inverted by tensile stress. Thick crack L1 arises by strong tensile stress, and the crack is going to spread by big tensile stress. Fig. 4C is a diagram showing a cross section C-C 'of a region where the tensile stress is weakened after the cooling spot passes. The thin crack L2 remains narrower than the coarse crack L1 due to the weak tensile stress. Fig. 4 (d) is a diagram showing the cross-section D-D 'when the time has elapsed, the tensile stress is lost, and is reversed to the weak compressive stress again. In this region, due to the weak compressive stress, the thin crack L2 seen so far becomes an invisible crack L3 (called a blind crack).

Next, the crack formation method of this invention is demonstrated. It is a figure which shows each process of the crack formation method which is one Embodiment of this invention. In this embodiment, each process of a 1st crack formation process, the attachment process of a friction coefficient lowering agent, and a 2nd crack formation is performed, but it is made to perform a 1st crack formation and adhesion of a frictional coefficient lowering agent simultaneously.

FIG. 5A is a diagram illustrating a first crack forming step and a step of attaching a friction coefficient lowering agent. In the first crack forming step (and the step of attaching the friction coefficient lowering agent), the laser scribing described in FIGS. 3 and 4 is performed. The only difference is that the refrigerant contains a small amount of silicone oil which is a friction coefficient lowering agent.

That is, the laser beam LB is irradiated onto the substrate G to form an elliptic beam spot BS. In addition, a coolant is injected from the cooling nozzle CN to form a cooling spot CS. The positions of the beam spot BS and the cooling spot CS are fixed, and a table (not shown) on which the substrate G is placed is driven to separate the scheduled line L0 of the substrate G toward the X direction. By moving along, the beam spot BS and the cooling spot CS are scanned to cross the substrate G from the initial crack TR. As a result, the first crack X-1 is formed.

The coolant is contained in the water (original coolant) at 1% or less, for example, 0.4%, of silicone oil, which is a friction coefficient lowering agent, and is allowed to be sprayed from the nozzle together with the compressed air. When the concentration of the silicone oil is increased, the injection cannot be carried out from the nozzle, so that the concentration is considerably lighter.

In this way, the friction coefficient lowering agent is injected together with the refrigerant. Immediately after the coolant is injected, the coarse crack L1 is formed. As described with reference to Fig. 4B, in the large crack L1, the crack is spread by a large tensile stress, and the silicone oil easily adheres to the crack. Subsequently, as time passes, the crack L2 (blind crack) becomes invisible through the fine crack L2, but the coefficient of friction in the crack is reduced by the adhered silicone oil. Subsequently, a second crack formation process is performed.

FIG. 5B is a diagram illustrating a second crack formation process. FIG. In the second crack forming step, the laser scribing described in FIGS. 3 and 4 is performed with the scanning direction of the substrate G toward the Y direction. Since the coolant at this time does not need to include a frictional coefficient lowering agent, a coolant exclusively of water and compressed air may be used. The first crack formation process (and friction) is performed unless there is an adverse effect caused by silicone oil (frictional coefficient lowering agent). What is necessary is just to use the refrigerant | coolant used by the adhering process of a coefficient lowering agent) as it is. In the second crack forming step, the scanning spot CS reaches the intersection point F with the first crack X-1 and continues scanning until the first crack exceeds the first crack.

FIG. 6: is a figure which shows the state where the front-end | tip of the cooling spot CS reached | attained 1st crack X-1, FIG. 6 (a) is a perspective view, FIG. 6 (b) is a top view. 6 (c) to 6 (d) are enlarged views of different states of the region S of FIG. 6 (b), respectively. 6 (c) shows a state of the region S before the cooling spot CS reaches the region S, and FIG. 6 (d) shows that silicone oil is attached to the first crack X-1. Area (S) of FIG. 6 (b) and FIG. 6 (e) are comparative examples, and the area (S) of FIG. 6 (b) when no silicone oil is attached to the first crack (X-1). )to be.

Four markers P1-P4 are shown by FIG.6 (c)-FIG.6 (e). These are markers attached for convenience in order to explain the positional change of the substrate by the second crack forming step by the movement of the marker.

At this time, the first crack X-1 is an invisible crack L3 (blind crack), but silicon oil (friction coefficient lowering agent) is attached to the crack.

As shown in FIG.6 (c), before the cooling spot CS reaches | attains the area | region S, a crack has not generate | occur | produced in the division planned line L0 of a Y direction. The four markers P1 to P4 at this time are pasted at an equidistant distance from the intersection point F between the first crack X-1 and the dividing scheduled line L0.

After that, when the cooling spot CS reaches the region S, as shown in Fig. 6D, the second crack Y-1 is formed along the division scheduled line L0. Immediately after the cooling spot CS passes, a strong tensile stress is generated, and the second crack Y-1 is a coarse crack L1. At this time, the tip of the second crack Y-1 stops at the intersection point F. As shown in FIG. This is because the friction coefficient in the crack of the first crack (X-1) is lowered due to the adhesion of the silicone oil, so that the tensile stress generated on the P1 side (P2 side) exceeds the intersection point F and the P4 side (P3 side). Because it is not delivered to. At this time, the crack surface on the P1 side (P2 side) slides in the direction of the arrow with respect to the crack surface on the P4 side (P3 side), so that the progress of the crack is stopped.

At this time, the beam spot BS has reached the front (P3, P4 side) beyond the intersection point F, but does not advance the crack just by applying the compressive stress. The crack cannot advance even if some heating is performed on the P4 side (P3 side) unless the initial crack TR is formed at the intersection point F.

FIG. 6E shows a comparative example in which the cooling spot CS reaches the region S when the silicon oil is not adhered to the crack of the first crack X-1.

Since the compressive stress is generated in the crack surface of the first crack X-1, when the crack surface on the P1 side (P2 side) moves along the direction of the first crack due to friction, the P4 side (P3 side) The crack face moves as if dragged by friction. That is, the P4 side moves in conjunction with the movement of the P1 side, and the P3 side moves in conjunction with the movement of the P2 side.

Therefore, in the second crack formation step, if a strong tensile stress occurs immediately after the cooling spot CS passes, and the second crack Y-1 becomes a large crack L1, it spreads beyond the intersection point F. Coarse crack L1 is transmitted, and coarse crack L4 which spreads by the same crack width as crack L1 is formed. That is, the crack advances forward without stopping at the intersection.

(Example)

(Experiment)

A comparative experiment was conducted between the case where the refrigerant contained silicone oil as the friction coefficient lowering agent and when the refrigerant was not contained.

The experimental conditions are shown below.

Glass substrate alkali-free glass (＃ 1737 made by Corning Corporation)

Laser power 160W

Scanning Speed 200mm / sec

2ml / min refrigerant injection

Crack depth 125㎛

Refrigerant Water 99.6%

Silicone oil 0.4% (product made by Shin-Etsukagaku Kogyo KK)

KF-643)

Sprayed with compressed air at the mixing ratio

Under the above conditions, laser scribing was performed. First, when the first crack is formed in the X direction, then the second crack is formed in the Y direction, and the second crack is formed, the beam spot BS and the cooling spot CS intersect with the first crack. The injection was made until it was over.

As a result, the second crack completely stopped at the intersection and did not go forward beyond the first crack.

As a comparative example, as a result of performing the same laser scribing process by changing the refrigerant to 100% water (silicone oil 0%), the second crack proceeded forward beyond the first crack without stopping at the intersection.

From the above results, it was found that by adhering a small amount of silicone oil (friction coefficient lowering agent) into the crack of the first crack, the progress of the crack can be suppressed at the intersection point.

In addition, materials other than silicone oil were also studied for materials acting as friction coefficient lowering agents. As a result, a material in which an alkyl alcohol, an alkyl ether, a fatty acid alkyl ester (having a linear or branched alkyl group having 1 to 30 carbon atoms), which is a material having an alkyl group, as a solution by adding alcohol is contained in the refrigerant as a friction coefficient lowering agent. Also in this case, the effect of stopping the progress of cracking was obtained.

(Modification Embodiment)

In the above embodiment, the silicon oil (friction coefficient lowering agent) is injected with the refrigerant using the cooling nozzle, but the second nozzle is provided behind the cooling nozzle, and the silicone oil (friction coefficient lowering agent) is sprayed only on the necessary portion. You may also That is, the silicon oil is to be attached only in the vicinity of the intersection point (F). By doing in this way, the influence of a silicone oil can be suppressed to the minimum in the case of the use which cares about adhesion of silicone oil.

Moreover, in the said embodiment, although silicone oil was affixed by the injection from a nozzle, you may adhere | attach by application | coating. Even in that case, it is easy to apply | coat the coating immediately after cooling in a crack.

In the second crack forming step, when the beam spot reaches the intersection with the first crack, when the laser irradiation is stopped and the beam spot is erased, not only the crack progresses but also the adverse effect on the substrate due to heating It can also be suppressed. In that case, by moving the cooling spot to the intersection and stopping the movement of the cooling spot, the second crack is surely formed up to the intersection.

(Industrial availability)

The crack formation method of this invention can be used for the division | segmentation of brittle material substrates, such as a glass substrate.

10 Round member 11 Strip member
BS beam spot CS cooling spot
Segmented line L1 Thick crack
L2 Fine Crack L3 Blind Crack
F Intersection X-1 First Crack
Y-1 second crack

Claims (7)

A laser scribe for irradiating a laser beam to a brittle material substrate to form a beam spot, relative movement of the beam spot to heat below the temperature at which the substrate softens, and subsequently cooling the substrate along a trajectory through which the beam spot has passed. As a crack formation method of a brittle material substrate which forms a crack by a process,
The first crack is formed by the first laser scribe processing,
Attaching a coefficient of friction lowering agent to lower the coefficient of friction in the crack of the first crack, and then forming a second crack up to an intersection with the first crack in a direction intersecting the first crack by a second laser scribe process;
Stopping the progress of the second crack at the intersection with the first crack. The method of claim 1, wherein the friction coefficient lowering agent contains a lubricating oil. 3. The method of claim 2 wherein the coefficient of friction lowering agent contains silicone oil. The method of claim 1, wherein the friction coefficient lowering agent contains any one of an alkyl alcohol, an alkyl ether, and a fatty acid alkyl ester. The method of claim 1, wherein the friction coefficient lowering agent is sprayed together with the refrigerant when cooling the substrate in the first laser scribing process. 6. The crack formation method according to claim 5, wherein water containing silicone oil is used as said refrigerant. The crack forming method according to claim 1, wherein the friction coefficient lowering agent is applied or sprayed near the intersection immediately after cooling the substrate in the first laser scribing process.

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