TW201808841A - Method for breaking brittle substrate applicable to manufacturing process of flat panel display panels or solar panels by precisely controlling the angle of a breaking section with respect to the surface of a brittle substrate - Google Patents

Abstract

The present invention controls with high precision the angle of a breaking section with respect to the surface of a brittle substrate. A brittle substrate 4 having a first surface SF1 and a second surface SF2 opposite to the first surface SF1 are prepared. By irradiating a laser light having an optical axis LA on the first surface SF1 of the brittle substrate 4, the property of the brittle substrate 4 is partially modified, thereby forming a modified area RA. By moving the front edge of a blade on any one of the first surface SF1 and the second surface SF2 of the brittle substrate 4, a crack line CL is thus formed. The crack line CL is extended through the modified area RA of the brittle substrate 4, so as to form a partitioning surface PS on the brittle substrate 4. The step of forming the modified area RA and the step of forming the crack line CL are performed in a manner that the crack line CL is disposed offset from the optical axis LA of the laser light.

Description

Breaking method of brittle substrate

The invention relates to a method for breaking a brittle substrate.

In the manufacture of electrical equipment such as flat panel display panels or solar panels, it is often necessary to break the fragile substrate. In a typical breaking method, first, a crack line is formed on a brittle substrate. In the present specification, the "crack line" refers to a person who has a crack extending partially in the thickness direction of the brittle substrate in a linear manner on the surface of the brittle substrate. Then, a so-called breaking step is performed. Specifically, by applying stress to the fragile substrate, the crack of the crack line is completely penetrated into the thickness direction. Thereby, the fragile substrate is broken along the crack line.

According to Patent Document 1, a recessed portion on the upper surface of a glass plate is generated when scribing. In this patent document 1, this recessed part is called "engraved line". In addition, at the same time as the scribe line is engraved, a crack extending from the scribe line downward to the nearest place is generated. As can be seen from the technique of Patent Document 1, in the conventional typical technique, a scribe line is formed while a crack line is formed.

According to Patent Document 2, a breaking technique that is significantly different from the typical breaking technique described above is proposed. According to this technique, first, the edge of a blade slides on a brittle substrate to plastically deform it, thereby forming a groove shape called a "engraved line" in Patent Document 2. In this specification, the groove shape is hereinafter referred to as a "groove line". At the time the slot line was formed, A crack formed below. Subsequently, the crack is stretched along the groove line, thereby forming the crack line. That is, unlike the typical technique, a groove line without accompanying cracks is formed first, and then a crack line is formed along the groove line. Subsequently, the usual breaking step is performed along the crack line.

The groove line not accompanied by a crack used in the technique of the aforementioned Patent Document 2 can be formed by sliding the leading edge of the blade with a lower load than a typical scribe line formed simultaneously with the crack. Because the load is small, the damage to the leading edge of the blade is reduced. Therefore, according to this breaking technology, the leading edge life can be extended.

In many cases, in the breaking of a brittle substrate using a crack line, it is desirable that the crack line extends vertically in the brittle substrate with respect to its surface. Thereby, a divided surface perpendicular to the substrate surface can be obtained. On the other hand, depending on the use or shape of the divided brittle substrate, it may be desirable to form a divided surface that is inclined with respect to the substrate surface. For example, in the case where the fragile substrate is broken along a closed curve, assuming that a broken surface perpendicular to the substrate surface is formed by the breaking step, it is easy to make it difficult to extract the inner portion of the closed curve from the outer portion after the breaking step. In order to make it easy, it is necessary to incline the cutting surface to the surface of the substrate, in other words, it is necessary to set a draft angle.

According to Patent Document 3, in order to set the draft slope, a diamond disc saw as a cutter is used to draw a closed curve on one side of the glass plate to form a cut inclined to the thickness direction of the glass plate. Pattern. Two methods are exemplified as methods for making the cut lines be inclined. As a first method, a diamond disc saw was used in an inclined state. As a second method, a diamond disc saw having an asymmetric shape is used.

Prior art literature

Patent literature

Patent Document 1: Japanese Patent Application Laid-Open No. 9-188534

Patent Document 2: International Publication No. 2015/151755

Patent Document 3: Japanese Patent Application Laid-Open No. 7-223828

According to the method of the aforementioned Patent Document 3, when a crack line is formed on one surface of a brittle substrate, the crack line can be extended in a desired inclined direction near the surface. However, in order to break the substrate, the crack line must be stretched to the opposite surface of the substrate. In the process, the stretching direction may change due to some difficult to control factors. Therefore, a sectional surface inclined in a desired direction may not be obtained in some cases.

The present invention is made to solve the problems described above, and an object thereof is to provide a method for breaking a brittle substrate, which can accurately control the angle of the breaking surface with respect to the surface of the brittle substrate.

The method for cutting a fragile substrate of the present invention includes the steps of preparing a fragile substrate having a first surface and a second surface opposite to the first surface; and irradiating laser light having an optical axis to the first surface of the fragile substrate. On the other hand, the brittle substrate is locally deteriorated, thereby forming a deteriorated region; the leading edge of the blade is moved on any of the first surface and the second surface of the brittle substrate, thereby forming a crack line; and the crack line is passed through the brittle substrate. The deformed area is stretched, thereby forming a section on the brittle substrate. The step of forming a deteriorated region and the step of forming a crack line are performed in such a manner that the crack line is offset from the optical axis of the laser light.

According to the present invention, a laser light having an optical axis is irradiated onto the first surface of the fragile substrate to locally deteriorate the fragile substrate, thereby forming a deteriorated region. The crack lines are arranged offset from the optical axis of the laser light. Thereby, the extending direction of the crack line can be fine-tuned on the first surface of the brittle substrate. Therefore, the angle of the divided surface with respect to the first surface of the fragile substrate can be controlled.

AL‧‧‧Auxiliary line

CL‧‧‧ Rift Line

LA‧‧‧ Optical axis

PS‧‧‧ Section

RA‧‧‧ Metamorphic area

SC‧‧‧Scanning direction

SF1‧‧‧upper surface (first side)

SF2‧‧‧ lower surface (second side)

SP‧‧‧ Light Spot

TL‧‧‧Slot

4‧‧‧ glass substrate (brittle substrate)

4i‧‧‧ inside part

4o‧‧‧outer part

FIG. 1 is a flowchart schematically showing the configuration of a method for cutting a fragile substrate in Embodiment 1 of the present invention.

FIG. 2 is a plan view schematically showing a first step of a method for cutting a fragile substrate in Embodiment 1 of the present invention.

FIG. 3 is a schematic cross-sectional view taken along the line III-III of FIG. 2.

FIG. 4 is a plan view showing an example of a light point and an optical axis of laser light used to form the deteriorated region of FIG. 2.

FIG. 5 is a plan view showing a case of scanning using the light spot of FIG. 4. FIG.

FIG. 6 is a graph showing an example of the intensity distribution of the light spot in FIG. 4 in a direction perpendicular to the scanning direction.

FIG. 7 is a plan view schematically showing a second step of the method for cutting a fragile substrate in Embodiment 1 of the present invention.

FIG. 8 is a schematic cross-sectional view taken along the line VIII-VIII of FIG. 7.

FIG. 9 is a plan view schematically showing the third step of the method for cutting a fragile substrate in Embodiment 1 of the present invention.

Fig. 10 is a schematic cross-sectional view taken along the line X-X in Fig. 9.

FIG. 11 is a plan view schematically showing one step of a method for breaking a fragile substrate in Embodiment 2 of the present invention.

FIG. 12 is a schematic cross-sectional view taken along the line XII-XII of FIG. 11.

FIG. 13 is a plan view schematically showing one step of a method for breaking a fragile substrate in Embodiment 2 of the present invention.

FIG. 14 is a schematic cross-sectional view taken along the line XIV-XIV in FIG. 13.

FIG. 15 is a flowchart schematically showing a configuration of a method for cutting a fragile substrate in Embodiment 3 of the present invention.

FIG. 16 is a plan view schematically showing one step of a method for breaking a fragile substrate in Embodiment 3 of the present invention.

FIG. 17 is a schematic cross-sectional view taken along the line XVII-XVII of FIG. 16.

FIG. 18 is a plan view schematically showing a step of a method for breaking a fragile substrate in Embodiment 2 of the present invention.

FIG. 19 is a schematic cross-sectional view taken along the line XIX-XIX of FIG. 18.

FIG. 20 is a plan view schematically showing a second step of a method for cutting a fragile substrate in a modified example of Embodiment 3 of the present invention.

FIG. 21 is a plan view schematically showing a third step of the method for cutting a fragile substrate in a modification of the third embodiment of the present invention.

Fig. 22 is a plan view schematically showing a first step of a method for cutting a fragile substrate in Embodiment 4 of the present invention.

FIG. 23 is a schematic cross-sectional view taken along the line XXIII-XXIII of FIG. 22.

FIG. 24 is a plan view schematically showing a second step of the method for cutting a fragile substrate in Embodiment 4 of the present invention.

FIG. 25 is a schematic cross-sectional view taken along the line XXV-XXV in FIG. 24.

Fig. 26 is a plan view schematically showing a first step of a method for cutting a fragile substrate in a modification of the fourth embodiment of the present invention.

Fig. 27 is a plan view schematically showing a second step of the method for cutting a fragile substrate in a modification of the fourth embodiment of the present invention.

FIG. 28 is a plan view schematically showing a first step of a method for cutting a fragile substrate in Embodiment 5 of the present invention.

FIG. 29 is a schematic cross-sectional view taken along the line XXIX-XXIX of FIG. 28.

FIG. 30 is a plan view showing a case where a light spot and an optical axis of laser light used for forming a deteriorated region of FIG. 28 are scanned.

Fig. 31 is a plan view schematically showing a second step of the method for cutting a fragile substrate in Embodiment 5 of the present invention.

FIG. 32 is a schematic cross-sectional view taken along the line XXXII-XXXII of FIG. 31.

FIG. 33 is a plan view schematically showing a third step of the method for cutting a fragile substrate in Embodiment 5 of the present invention.

FIG. 34 is a schematic cross-sectional view taken along the line XXXIV-XXXIV of FIG. 33.

FIG. 35 is a plan view schematically showing one step of a method for cutting a fragile substrate in a modification of the fifth embodiment of the present invention.

FIG. 36 is a schematic cross-sectional view taken along the line XXXVI-XXXVI of FIG. 35.

Fig. 37 is a schematic view showing a breaking direction of a brittle substrate in a modification of the fifth embodiment of the present invention; Top view of one step of the method.

FIG. 38 is a schematic cross-sectional view taken along the line XXXVIII-XXXVIII of FIG. 37.

39 is a plan view schematically showing a first step in an example of a method for forming a crack line in Embodiment 5 of the present invention.

FIG. 40 is a schematic cross-sectional view taken along the line XL-XL of FIG. 39. FIG.

41 is a plan view schematically showing a second step in the example of the method for forming a crack line in Embodiment 5 of the invention.

FIG. 42 is a schematic cross-sectional view taken along the line XLII-XLII of FIG. 41. FIG.

FIG. 43 is a cross-sectional view showing the respective definitions of the interval DS between the crack line and the optical axis formed on the upper surface of the glass substrate, and the guide amount DI of the extension path of the crack line.

FIG. 44 is a cross-sectional view showing the definitions of the interval DS between the crack line and the optical axis formed on the lower surface of the glass substrate, and the guide amount DI of the extension path of the crack line.

Fig. 45 is a graph showing the experimental results of the relationship between the interval DS and the guide amount DI in the respective cases of Figs. 43 and 44;

Hereinafter, embodiments of the present invention will be described based on the drawings. Moreover, in the following drawings, the same or equivalent parts are marked with the same reference numerals, and the description will not be repeated.

<Embodiment 1>

Hereinafter, a method for dividing a brittle substrate in this embodiment (FIG. 1) will be described.

2 and FIG. 3, in step S20 (FIG. 1), a glass substrate 4 (brittle substrate) is prepared. The glass substrate 4 (brittle substrate) has an upper surface SF1 (first surface) and a lower surface. The surface SF2 (the second surface opposite to the first surface) has a thickness direction perpendicular to the upper surface SF1. The glass substrate 4 is, for example, an alkali-free glass. The thickness of the glass substrate 4 is preferably 0.7 mm or less, and more preferably 0.5 mm or less.

Then, in step S40 (FIG. 1), the laser light having the optical axis LA is irradiated onto the upper surface SF1 of the glass substrate 4, so that the glass substrate 4 is partially deteriorated. Thereby, a deteriorated area RA is formed. The deteriorated area RA is an area in the glass substrate 4 where internal stress changes due to instantaneous heating by laser light. In addition, the range in which the modified region RA is formed may be a part of the thickness direction of the glass substrate 4 as shown in FIG. 3, or may be the entire thickness direction of the glass substrate 4. The range in which the deterioration region RA is formed varies depending on the thickness of the glass substrate 4, the intensity of the laser light, the focal position, and the like.

Typically, the laser light is irradiated by scanning a light spot SP (FIG. 4) having an optical axis LA on the upper surface SF1 in the scanning direction SC as shown in FIG. 5. At this time, the optical axis LA (FIG. 2) used in the formation of the finally deteriorated region RA is a collection of the instantaneous optical axis LA (FIG. 4) (in other words, the trajectory of the optical axis LA). The light spot SP has, for example, a circular shape with a diameter of several millimeters. The scanning of the laser light is performed, for example, by moving a light spot SP generated by a pulse of several kHz in the scanning direction SC at a speed of several tens of mm / second. Referring to FIG. 6, typically, the optical axis LA is the central axis of the distribution of the intensity I of the light spot SP in the direction X perpendicular to the scanning direction SC. The output of the laser light is, for example, about several tens of W. If the output is too low, the glass substrate 4 cannot be sufficiently modified. If the output is too high, the damage to the glass substrate 4 will become excessive, and the glass substrate 4 may be cracked in some cases. The laser light is generated by, for example, a CO ₂ laser.

7 and 8, in step S60 (FIG. 1), the leading edge (not shown) of the blade is moved on the upper surface SF1 of the glass substrate 4. Utilizing machining that moves by the leading edge of the blade, A crack line CL is formed. The formation of the crack line CL itself can be performed by a general scoring method. The aforementioned step of forming the deterioration region RA and the step of forming the crack line CL are performed in such a manner that the crack line CL is offset from the optical axis LA of the laser light.

Referring to FIGS. 9 and 10, in step S80 (FIG. 1), the crack line CL is extended through the modified region RA of the glass substrate 4, thereby forming a split surface PS on the glass substrate 4. That is, a breaking step of breaking the glass substrate 4 along the crack line CL is performed. The breaking step can be performed by applying an external force to the glass substrate 4. For example, toward the crack line CL (FIG. 8) on the upper surface SF1 of the glass substrate 4, a stress-applying member (for example, a member called a “breaking rod”) is pressed onto the lower surface SF2, and the glass substrate 4 is thereby pressed. A stress is applied to crack the crack of the crack line CL. Moreover, when the crack line CL is completely penetrated into the thickness direction at the time of formation (FIG. 8), the formation of the crack line CL and the disconnection of the glass substrate 4 occur at the same time.

According to experiments by the inventors, a phenomenon in which the extension path of the crack line CL (the dotted arrow in FIG. 10) is guided toward the optical axis LA is observed (see the solid arrow in FIG. 10). This phenomenon is considered to be caused by the distribution of the internal stress generated in the glass substrate 4 when the deteriorated region RA is formed. By utilizing this phenomenon, the direction in which the crack line CL extends with respect to the upper surface SF1 (the direction of extension in FIG. 10) can be fine-tuned. That is, the angle of the divided surface PS with respect to the upper surface SF1 can be controlled.

According to the experimental results described below, the guide amount of the extension path of the crack line CL is the offset between the optical axis LA and the crack line CL on the upper surface SF1 (the distance between the optical axis LA and the crack line CL in FIG. 7). The interval is maximized. That is, regardless of whether the offset amount is too small or too large, the guidance effect brought by the deteriorated area RA becomes small. The optimum value of the offset amount is, for example, about several hundred μm. The guide amount of the extension path of the crack line CL can be determined by the solid arrow in FIG. 10 The size of the upward section PS is, for example, about 10 μm to several tens μm.

In addition, according to the present embodiment, both the modified region RA and the crack line CL are formed on the upper surface SF1. Thereby, compared with the case where the modified region RA is formed on the upper surface SF1 and the crack line CL is formed on the lower surface SF2 as in the second embodiment described later, steps can be facilitated.

Moreover, according to this embodiment, a crack line CL is formed after the modified region RA is formed. Thereby, in the vicinity of the starting point of the crack line CL, in other words, near the upper surface SF1, the extension direction of the crack line CL can also influence the deterioration region RA.

Furthermore, as a modification, after the crack line CL is formed, a modified region RA is formed, and then the crack line CL is extended to the lower surface SF2. However, in order for the deteriorated region RA to act more reliably and sufficiently on the crack line CL, as described above, it is preferable to form the deteriorated region RA before the formation of the crack line CL.

<Embodiment 2>

In the first embodiment, the crack line CL is formed on the upper surface SF1, but in the present embodiment, the crack line CL is formed on the lower surface SF2. Hereinafter, a method for cutting the glass substrate 4 in this embodiment will be specifically described.

First, as in the first embodiment, a modified region RA is formed on the glass substrate 4 (FIGS. 2 and 3). Referring to FIGS. 11 and 12, in this embodiment, the leading edge of the blade is moved on the lower surface SF2 of the glass substrate 4 to form a crack line CL.

Referring to FIGS. 13 and 14, the crack line CL is extended through the modified region RA of the glass substrate 4, thereby forming a split surface PS on the glass substrate 4. That is, a breaking step of breaking the glass substrate 4 along the crack line CL is performed. The breaking step can be performed by applying to the glass substrate 4 External force. For example, toward the crack line CL (FIG. 12) on the lower surface SF2 of the glass substrate 4, a stress-applying member (for example, a member called a “break bar”) is pressed onto the upper surface SF1, thereby applying the glass substrate 4 to the glass substrate 4. The stress that cracks the crack of the crack line CL. Furthermore, when the crack line CL completely penetrates the thickness direction at the time of formation (the time in FIG. 12), the formation of the crack line CL and the disconnection of the glass substrate 4 occur at the same time.

According to experiments by the present inventors, it is observed that the extension path of the crack line CL (the dotted arrow in FIG. 14) is intended to approach the optical axis LA (refer to the solid arrow in FIG. 14). This phenomenon is considered to be caused by the distribution of the internal stress generated in the glass substrate 4 when the deterioration region RA is formed. By utilizing this phenomenon, the direction in which the crack line CL extends with respect to the upper surface SF1 (the extending direction in FIG. 14) can be fine-tuned. That is, the angle of the divided surface PS with respect to the upper surface SF1 can be controlled.

According to the experimental results described later, the amount of guidance of the extension path of the crack line CL is the offset between the optical axis LA and the crack line CL on the lower surface SF2 (the distance between the optical axis LA and the crack line CL in FIG. 11). The interval is maximized. That is, regardless of whether the offset amount is too small or too large, the guidance effect brought by the deteriorated area RA becomes small. The optimum value of the offset amount is, for example, about several hundred μm. The guide amount of the extension path of the crack line CL can be represented by the size of the section PS in the direction of the solid line arrow in FIG. 14, and is, for example, about 10 μm to several tens μm.

Moreover, according to this embodiment, after the modified region RA is formed, a crack line CL is formed. Thereby, in the vicinity of the starting point of the crack line CL, in other words, near the lower surface SF2, the extension direction of the crack line CL can also influence the deterioration region RA. Furthermore, according to the present embodiment, the crack line CL is formed by the movement of the leading edge of the blade on the lower surface SF2 where the deterioration region RA is not formed. Thereby, the degradation of the crack line CL due to the damage caused by the laser light is avoided.

Furthermore, as a modification, after the crack line CL is formed, a modified region RA is formed, and then the crack line CL is extended to the upper surface SF1. However, in order for the deteriorated region RA to act more reliably and sufficiently on the crack line CL, as described above, it is preferable to form the deteriorated region RA before the formation of the crack line CL.

<Embodiment 3>

In this embodiment, the method of forming the crack line CL (FIGS. 7 and 8) is different from that in the first embodiment. Hereinafter, a method for cutting the glass substrate 4 in this embodiment will be specifically described.

First, as in the first embodiment, in steps S20 and S40 (FIG. 15), a glass substrate 4 is prepared and a modified region RA is formed. Furthermore, step S40 (FIG. 15) may be performed after step S60 (FIG. 15) described later.

16 and 17, in step S50 (FIG. 15), as shown by an arrow (FIG. 16), the leading edge of the blade is moved on the upper surface SF1 (FIG. 17) of the glass substrate 4, thereby making Plastic deformation occurs on the upper surface SF1. Thereby, a groove line TL having a groove shape is formed. This forming step is performed in such a manner that a crack-free state can be obtained. The crack-free state refers to the nearest position below the slot line TL, and the glass substrate 4 is continuously connected in the direction RT (FIG. 17) crossing the slot line TL. Of the state. In the crack-free state, although the groove line TL is formed by plastic deformation, no crack is formed along it. In order to obtain a crack-free state, it is only necessary to avoid excessive load on the leading edge of the blade.

The groove line TL is preferably generated only by plastic deformation of the glass substrate 4. In this case, no planing on the glass substrate 4 occurs. In order to avoid planing, the load on the leading edge of the blade should not be too high. By avoiding planing, unwanted fine fragments are prevented from being generated on the glass substrate 4. However, a small amount of gouging is usually tolerated.

18 and 19, in step S60 (FIG. 15), cracks are formed. Trace CL. This forming step is performed by extending a crack from the groove line TL. In this embodiment, as shown in FIG. 16, the micro-fracture caused by cutting down the edge of the glass substrate 4 at the leading edge of the blade at the position NP is used as a starting point, and as shown by the arrow in FIG.

Next, in step S80 (FIG. 15), the terrain component cross section PS (FIG. 10) is the same as that of the first embodiment. That is, the glass substrate 4 is divided.

In this embodiment, the same effects as those of the first embodiment can be obtained. Furthermore, in this embodiment, after the slot line TL is formed in a crack-free state as shown in FIG. 17, as shown in FIG. 19, a crack line CL is formed immediately below the slot line TL. According to the study by the present inventors, by this method, the sectional surface along the crack line CL can be made smoother than that in the first embodiment.

In addition, the formation of the crack line CL in this embodiment is considered to be generated by releasing internal stress generated when the groove line TL is formed. This opportunity for stress relief is not limited to cutting under the edge of the glass substrate 4 as described above (Fig. 16). Hereinafter, a modified example from this viewpoint will be described.

First, as in the first embodiment, in steps S20 and S40 (FIG. 15), a glass substrate 4 is prepared to form a modified region RA. Furthermore, step S40 (FIG. 15) may be performed after step S60 (FIG. 15) described later. 20, in step S50 (FIG. 15), a slot line TL is formed. Unlike the aforementioned step of FIG. 16, in this modification, the leading edge of the blade does not cut the edge of the glass substrate 4.

Referring to FIG. 21, in step S60 (FIG. 15), an auxiliary line AL crossing the groove line TL is formed on the upper surface SF1 (the surface shown in FIG. 21) of the glass substrate 4. Taking this as an opportunity, as shown by the arrow in the figure, a crack line CL starts to form.

In step S80 (FIG. 15), it is then formed in the same manner as in the first embodiment. Sectional PS. That is, the glass substrate 4 is divided.

Moreover, the aforementioned movement of the leading edge of the blade on the glass substrate 4 may be any of sliding and rotating. In the case of sliding, use the front edge of the blade fixed to the bracket (such as a diamond tip). In the case of rotation, a leading edge (so-called scribing wheel) which is rotatably held about the axis of the bracket is used. In terms of accurately managing the relative position of the groove line TL and the optical axis LA, the leading edge of the sliding blade is superior to the leading edge of the rotating blade.

After the formation of the groove line TL and the crack line CL (in other words, after the formation of the auxiliary line AL), a modified region RA may be formed. Thereby, the slot line TL can be formed without being affected by the damage caused by the laser light, and further, the vicinity of the starting point of the crack line CL can also influence the extension direction of the crack line CL to bring about the deterioration region RA.

<Embodiment 4>

In each of the third embodiment (FIGS. 16 to 19) and its modification (FIGS. 20 and 21), the groove line TL and the crack line CL are formed on the upper surface SF1. On the other hand, in this embodiment (FIGS. 22 to 25) and its modifications (FIGS. 26 and 27), the groove line TL and the crack line CL are formed on the lower surface SF2.

In addition, the structure other than the above is substantially the same as that of the third embodiment or its modification, and therefore the same or corresponding elements are denoted by the same symbols, and the description thereof will not be repeated.

<Embodiment 5>

Referring to FIGS. 28 and 29, in the present embodiment, the step of forming a modified region RA is performed in such a manner that the optical axis LA has a curved portion on the upper surface SF1 of the glass substrate 4. More specifically, the step of forming the deterioration region RA is based on the optical axis LA on the upper surface SF1 of the glass substrate 4. This is done in a closed curve. Typically, the laser light is irradiated as shown in FIG. 30 by scanning the light spot SP having the optical axis LA on the upper surface SF1 in the scanning direction SC. At this time, the optical axis LA (FIG. 28) used in the formation of the metamorphic region RA finally obtained is a set of instantaneous optical axis LA (FIG. 30) (in other words, the trajectory of the optical axis LA).

Referring to FIGS. 31 and 32, in this embodiment, the step of forming the crack line CL is performed in such a manner that the crack line CL has a curved portion on the upper surface SF1 of the glass substrate 4. More specifically, the step of forming the crack line CL is performed so that the crack line CL forms a closed curve on the upper surface SF1 of the glass substrate 4.

In this embodiment, the step of forming the metamorphic region RA and the step of forming the crack line CL are performed such that the optical axis LA is disposed outside the closed curve of the crack line CL in a plan view (FIG. 31). The optical axis LA may have a shape in which the closed curve of the crack line CL is enlarged as shown in FIG. 31. In addition, as described in the first embodiment, the formation order of the modified region RA and the crack line CL is arbitrary.

Referring to FIGS. 33 and 34, the crack line CL is extended to form a split surface PS on the glass substrate 4. That is, a breaking step of breaking the glass substrate 4 along the crack line CL is performed. As shown in FIG. 34, the formed section PS has a tapered shape from the lower surface SF2 toward the upper surface SF1 by the action of the altered region RA.

In addition, the structure other than the above is substantially the same as that of the first embodiment, so the same or corresponding elements are denoted by the same symbols, and the description thereof will not be repeated.

According to this embodiment, when the outer portion 4o and the inner portion 4i are separated from each other after the formation of the sectional surface PS (FIG. 34), the tapered shape (FIG. 34) functions as the draft angle. Thereby, the inner portion 4i can be easily taken out from the outer portion 4o.

In addition, compared with the modification described later, the proportion of the deteriorated area RA in the inner portion 4i can be suppressed. This is useful when it is desired to suppress the influence of the laser light on the damage caused by the inner portion 4i.

Next, modifications will be described below.

Referring to FIG. 35 and FIG. 36, in this modification, the step of forming a modified region RA and the step of forming a crack line CL are such that the optical axis LA is disposed inside the closed curve of the crack line CL in a plan view (FIG. 35). And proceed. The optical axis LA may have a shape that reduces the closed curve of the crack line CL as shown in FIG. 35.

Referring to FIGS. 37 and 38, the crack line CL is extended to form a split surface PS on the glass substrate 4. That is, a breaking step of breaking the glass substrate 4 along the crack line CL is performed. As shown in FIG. 38, the formed sectional surface PS has a tapered shape from the upper surface SF1 to the lower surface SF2 by the action of the metamorphic region RA.

According to this modification, the tapered shape functions as the draft slope, and the inner portion 4i can be easily taken out from the outer portion 4o. Furthermore, compared with this embodiment described above, the proportion of the deteriorated area RA in the outer portion 4o can be suppressed. This is useful when it is desired to suppress the influence of the laser light on the damage caused by the outer portion 4o.

The method for forming the crack line CL in this embodiment and its modification is arbitrary, but as described in the third embodiment, after forming the groove line TL, the crack line CL may be formed using it. An example of this method will be described below.

Referring to FIG. 39 and FIG. 40, as shown by the arrows in the figure, the slot line TL is formed by moving the leading edge (not shown) of the blade on the upper surface SF1 with the position NQ as a starting point and an ending point. When the leading edge of the blade returns to the position NQ, a force is applied to the formed groove line TL by the leading edge of the blade.

Referring to FIG. 41 and FIG. 42, with the application of the above-mentioned force as an opportunity, the internal stress generated when the slot line TL is formed is released. Thereby, as shown by an arrow in the figure, a crack line CL is formed in a direction opposite to the formation direction of the groove line TL.

Moreover, in this embodiment, the crack line CL is formed in the upper surface SF1 similarly to Embodiment 1, but the crack line CL may be formed in the lower surface SF2 similarly to Embodiment 2.

[Example]

Referring to Fig. 43, as a first experiment, a split PS is formed by the method described in the first embodiment. The intervals DS between the optical axis LA and the crack line CL on the upper surface SF1 are set to 0 mm, 0.3 mm, 0.5 mm, and 0.7 mm. By measuring the surface distribution of the obtained sectional plane PS, the guide amount DI of the extension path of the crack line CL is investigated.

Referring to FIG. 44, as a second experiment, the split surface PS is formed by the method described in the second embodiment. The interval DS between the optical axis LA and the crack line CL on the lower surface SF2 is set to 0 mm, 0.3 mm, 0.5 mm, and 0.7 mm. By measuring the surface distribution of the obtained sectional plane PS, the guide amount DI of the extension path of the crack line CL is investigated.

In both of the first and second experiments, as the glass substrate 4, an alkali-free glass having a thickness of 0.3 mm was used. As the laser for forming the deterioration region RA, a CO2 laser having an output of 71 W and a pulse frequency of 5 kHz was used. The laser light spot is a circular shape with a diameter of 4 mm. The scanning speed of the light spot on the glass substrate 4 was set to 60 mm / second.

The results of each of the first and second experiments are shown in graphs E1 and E2 with reference to FIG. 45. Compared with the case where the interval DS is zero, when the interval DS is larger than zero, the guide amount DI becomes larger. The maximum value of the guide amount DI is obtained at an interval DS = 0.5 mm.

When the scanning speed is made slower, the glass substrate 4 may be cracked. The reason is presumably because the total energy per unit area incident on the glass substrate 4 due to the irradiation of the laser light becomes excessive. When the scanning speed is made faster, the maximum value of the obtained guide amount DI becomes smaller. The reason is presumably because the internal stress change in the glass substrate 4 caused by the irradiation of the laser light is small.

Furthermore, in each of the embodiments described above, the case where the glass substrate 4 is used as a brittle substrate has been described. However, the brittle substrate may be made of a brittle material other than glass, for example, ceramic, silicon, compound semiconductor, sapphire, or quartz Production.

4‧‧‧ glass substrate

CL‧‧‧ Rift Line

LA‧‧‧ Optical axis

PS‧‧‧ Section

RA‧‧‧ Metamorphic area

SF1‧‧‧upper surface

SF2‧‧‧ lower surface

Claims (6)

A method for breaking a fragile substrate includes the steps of preparing a fragile substrate having a first surface and a second surface opposite to the first surface; and irradiating laser light having an optical axis to the fragile substrate. On the first surface, partially deforming the fragile substrate to form a deteriorated region; and moving a leading edge of the blade on any of the first surface and the second surface of the fragile substrate, thereby The step of forming a crack line; and the step of extending the crack line through the deformed region of the brittle substrate, thereby forming a section on the brittle substrate, the step of forming a deformed region, and the step of forming a crack line, are This is performed so that the crack line is offset from the optical axis of the laser light. For example, the method for breaking a brittle substrate according to item 1 of the application, wherein the step of forming a crack line is performed by moving a leading edge of the blade on the first surface of the brittle substrate. For example, the method for breaking a brittle substrate according to the first patent application range, wherein the step of forming a crack line is performed by moving a leading edge of the blade on the second surface of the brittle substrate. According to the method for breaking a brittle substrate according to any one of claims 1 to 3, before the step of forming a crack line, it is provided that the edge of the blade is moved to the brittle substrate to make it plastic. Deformation, thereby forming a groove-shaped groove line. The above-mentioned step of forming the groove line is obtained in a state where the fragile substrate is continuously connected in a direction intersecting the groove line. Advance in a crack-free manner Yes, the step of forming a crack line is performed by extending the crack from the groove line. For example, the method for breaking a brittle substrate according to any one of claims 1 to 4, wherein the step of forming a crack line is performed in such a manner that the crack line has a curved portion on the brittle substrate. For example, the method for breaking a brittle substrate according to any one of claims 1 to 5, wherein the step of forming a crack line is performed in such a manner that the crack line forms a closed curve on the brittle substrate.