JP2017039217A - Method for formation of vertical crack in brittle material substrate and method for segmentation of brittle material substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method by which a vertical crack can be formed in a brittle material substrate without cullet.SOLUTION: A method for formation of a vertical crack in a brittle material substrate comprises: a trench line formation process in which a trench line, which is a linear groove part, is formed on one principal surface; and an impression formation process in which an impression is formed in such a manner that a portion near the trench line is locally pressed by a prescribed presser. In the trench line formation process, a trench line is so formed that a crackless state is maintained directly under the trench line, and a vertical crack is extended in a thickness direction of the brittle material substrate from the trench line according to formation of an impression in the impression formation process.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a method for dividing a brittle material substrate, and more particularly to a method for forming a vertical crack when dividing a brittle material substrate.

  A manufacturing process of a flat display panel or a solar cell panel generally includes a step of dividing a substrate (mother substrate) made of a brittle material such as a glass substrate, a ceramic substrate, or a semiconductor substrate. For such cutting, a technique is widely used in which a scribe line is formed on the substrate surface using a scribe tool such as a diamond point or a cutter wheel, and a crack (vertical crack) is extended from the scribe line in the thickness direction of the substrate. Yes. When the scribe line is formed, the vertical crack may be completely extended in the thickness direction and the substrate may be divided, but the vertical crack may be only partially extended in the thickness direction. In the latter case, after the scribe line is formed, stress is applied which is called a breaking process. The substrate is divided along the scribe line by causing the vertical crack to advance completely in the thickness direction by the breaking process.

  As a technique for extending a vertical crack by forming a scribe line, a technique for forming a linear processing trace, which is also referred to as an assist line, and serves as a starting point (trigger) in extending a vertical crack is already known. (For example, refer to Patent Document 1).

Japanese Patent Application Laid-Open No. 2015-74145

  When forming a scribe line using a scribe tool, fine swarf or powder cullet of the substrate material may be generated and adhere to the substrate surface.

  For example, in the case of a technique using an assist line as disclosed in Patent Document 1, when forming a scribe line for cutting, although the scribe tool hardly exerts a cullet on the substrate, When forming the assist line, cullet may be generated.

  This invention is made | formed in view of the said subject, and it aims at providing the method which can form a vertical crack, suppressing generation | occurrence | production of cullet than before.

  In order to solve the above-mentioned problem, the invention of claim 1 is a method of forming a vertical crack at a dividing position when dividing a brittle material substrate in the thickness direction, and has a linear shape on one main surface of the brittle material substrate. A trench line forming step of forming a trench line that is a groove portion, and an indentation forming step of forming an indentation by locally pressing the vicinity of the trench line of the brittle material substrate with a predetermined pressing body, In the trench line forming step, the trench line is formed so that a crackless state is maintained immediately below the trench line, and microcracks extending from the indentation with the formation of the indentation in the indentation forming step By reaching below the trench line, the vertical clock extends from the trench line in the thickness direction. Tsu is extended the click, characterized in that.

  Invention of Claim 2 is the formation method of the vertical crack in the brittle material board | substrate of Claim 1, Comprising: The front-end | tip part of the said predetermined press body has made cone shape, In the said indentation formation process, The indentation is formed by pressing the brittle material substrate with the conical tip.

  A third aspect of the present invention is the method for forming vertical cracks in the brittle material substrate according to the second aspect, wherein the tip of the predetermined pressing body has a conical shape.

  A fourth aspect of the invention is a method for forming a vertical crack in a brittle material substrate according to any one of the first to third aspects, wherein the indentation is formed on a side opposite to a predetermined extension direction of the vertical crack in the trench line. It is formed in the vicinity.

  The invention of claim 5 is a method of dividing the brittle material substrate in the thickness direction, and the vertical crack is formed in the brittle material substrate by the vertical crack forming method according to any one of claims 1 to 4. It comprises a vertical crack forming step and a breaking step for breaking the brittle material substrate along the vertical crack.

  According to the first to fifth aspects of the present invention, the vertical crack can be extended reliably and without causing cullet at the predetermined dividing position of the brittle material substrate.

It is a top view of the brittle material substrate W illustrating the state after the formation of the trench line TL. It is a figure which shows roughly the structure of the scribe tool 150 used for formation of trench line TL. It is zx partial sectional drawing containing the vertical cross section of trench line TL. It is zx partial sectional drawing which shows typically a mode at the time of lowering the press body. It is zx partial sectional drawing which shows typically a mode that indentation ID is formed with the press body. It is an optical microscope image about the vicinity of indentation ID at the time of forming indentation ID with respect to the glass substrate using the press body 100 in which the front-end | tip part 101 makes cone shape. It is a figure which shows typically a mode at the time of forming indentation ID in the vicinity of trench line TL. It is an optical microscope image about the vicinity of indentation ID at the time of forming indentation ID in the glass substrate formed by previously forming trench line TL. It is a top view of the brittle material board | substrate W which shows a mode that the vertical crack VC is extended by formation of indentation ID. It is a top view of the brittle material board | substrate W which shows a mode that the vertical crack VC is extended by formation of indentation ID. It is a graph which shows the relationship between a load and the diameter of formed indentation ID. It is a graph which shows the relationship between a load and the formed maximum crack length. It is an optical microscope image which shows the case where an indentation is formed using the press body 100 which the front-end | tip part 101 has comprised the shape of a quadrangular pyramid, and the vertical crack is extended just under the trench line TL.

  The method according to the embodiment of the present invention described below is to form a vertical crack for dividing at a predetermined position (dividing position) of the brittle material substrate W. Schematically speaking, the method is based on the substrate thickness direction from the trench line by forming a processing groove called a trench line for the dividing position and subsequently forming a local indentation in the vicinity of the trench line. It is intended to extend vertical cracks. In the present embodiment, the trench line is a fine line-shaped groove portion (concave portion) immediately below which a vertical crack is formed.

  Hereinafter, the case where a plurality of cutting positions (cutting lines) parallel to a pair of opposite sides are set in advance with respect to the rectangular brittle material substrate W will be described as an example. Also, in the drawing used for explanation, a right-handed xyz coordinate in which the arrangement direction of the dividing positions is the x-axis positive direction, the formation progress direction of the trench line TL is the y-axis positive direction, and the vertically upward direction is the z-axis positive direction. Is attached.

<Formation of trench lines>
FIG. 1 is a top view (xy plan view) of a brittle material substrate W exemplifying a state after the trench line TL is formed. FIG. 2 is a diagram schematically showing a configuration of the scribe tool 150 used for forming the trench line TL. FIG. 3 is a zx partial cross-sectional view including a vertical cross section of the trench line TL. The formation position of the trench line TL shown in FIG. 1 corresponds to a dividing position when the brittle material substrate W is viewed in plan view from the one main surface (upper surface) SF1 side.

  In the present embodiment, a scribe tool 150 having a diamond point 151 is used for forming the trench line TL. The diamond point 151 has a truncated pyramid shape as shown in FIG. 2, for example, and is provided with a top surface SD1 (first surface) and a plurality of surfaces surrounding the top surface SD1. More specifically, as shown in FIG. 2B, the plurality of surfaces include a side surface SD2 (second surface) and a side surface SD3 (third surface). The top surface SD1 and the side surfaces SD2 and SD3 face different directions and are adjacent to each other. At the diamond point 151, the cutting edge PS is formed by the ridgeline PS formed by the side surfaces SD2 and SD3 and the vertex PP formed by the three surfaces of the top surface SD1, the side surfaces SD2 and SD3. As shown in FIG. 2A, the diamond point 151 is held on the one end side of the bar-shaped (columnar) shank 152 in such a manner that the top surface SD1 is the lowest end.

  When the scribe tool 150 is used, as shown in FIG. 2A, the axial direction AX2 of the shank 152 is inclined by a predetermined angle from the vertical direction toward the front of the moving direction DA (y-axis positive direction). In this state, that is, with the top surface SD1 facing backward in the movement direction DA (y-axis negative direction), the diamond point 151 is brought into contact with the upper surface SF1 of the brittle material substrate W. Then, the cutting edge PF2 of the diamond point 151 is slid by moving the scribe tool 150 forward in the moving direction DA while maintaining such a contact state. As a result, plastic deformation along the moving direction DA of the diamond point 151 occurs. In the present embodiment, the sliding operation of the diamond point 151 that causes such plastic deformation is also referred to as a scribe operation by the diamond point 151.

  As shown in FIGS. 1 and 3, the trench line TL is formed as a fine line-shaped groove portion extending in the y-axis direction on the upper surface SF1 of the brittle material substrate W. The trench line TL is formed as a result of plastic deformation occurring in the upper surface SF1 of the brittle material substrate W by sliding the diamond point 151 in a state where the posture of the scribe tool 150 is symmetric with respect to the moving direction DA. . In such a case, as schematically shown in FIG. 3, the trench line TL is generally formed as a groove having a line-symmetric shape in a cross section perpendicular to the extending direction.

  As shown in FIG. 1, the trench line TL is formed from the start point T1 to the end point T2 in the positive y-axis direction indicated by the arrow AR1 at the dividing position defined on the upper surface SF1 of the brittle material substrate W. Hereinafter, a range relatively close to the start point T1 in the trench line TL is also referred to as an upstream side, and a range relatively close to the end point T2 is also referred to as a downstream side.

  In FIG. 1, the start point T1 and the end point T2 of the trench line TL are positioned slightly separated from the end of the brittle material substrate W. However, this is not an essential aspect, and the brittleness to be divided Either one or both of them may be the end position of the brittle material substrate W depending on the type of the material substrate W, the use of the separated pieces, or the like. However, the mode in which the start point T1 is the end of the brittle material substrate W is formed on the cutting edge PF2 of the scribe tool 150 as compared to the case where the start point T1 is a position slightly separated from the end as illustrated in FIG. Since the applied impact is increased, attention should be paid from the viewpoint of the life of the blade edge PF2 and the occurrence of unexpected vertical cracks.

  In addition, the formation of the trench line TL at each of the plurality of dividing positions may be an embodiment in which the trench line TL is sequentially formed by using the scribe tool 150 in a processing apparatus (not shown) provided with one scribe tool 150. It may be formed in parallel using a processing apparatus for forming the line TL.

  When the trench line TL is formed, the load applied by the scribe tool 150 (corresponding to a force for pushing the scribe tool 150 from the vertically upward to the upper surface SF1 of the brittle material substrate W) is surely formed. However, it is set so that the extension of the vertical crack from the trench line TL does not occur in the thickness direction DT of the brittle material substrate W (FIG. 3).

  In other words, the formation of the trench line TL is performed so that the brittle material substrate W is continuously connected in the direction intersecting the trench line TL (a crackless state) immediately below the trench line TL. When the trench line TL is formed in such a manner, internal stress remains as a result of plastic deformation in the vicinity of the trench line TL of the brittle material substrate W (in a range within about 5 μm to 10 μm from the trench line TL). To do.

  For example, the trench line TL is formed by setting the load applied by the scribe tool 150 to a smaller value than when forming the scribe line accompanied by the extension of the vertical crack using the same scribe tool 150. Realized.

  In the crackless state, even if the trench line TL is formed, the vertical crack does not extend from the trench line TL. Therefore, even if a bending moment acts on the brittle material substrate W, the vertical crack is formed. As compared with the case where it is formed, the division along the trench line TL is less likely to occur.

<Indentation formation and vertical crack extension>
When the trench line TL is formed in the above-described manner, subsequently, an indentation is locally formed in the vicinity of the trench line TL. Such indentation is formed by lowering a predetermined pressing body made of a material having sufficient hardness as compared with the brittle material substrate W and pressing the upper surface SF1 of the brittle material substrate W from above.

  FIG. 4 is a zx partial cross-sectional view schematically showing a state when the pressing body 100 is lowered, and FIG. 5 is a zx partial cross-sectional view schematically showing a state in which the indentation ID is formed by the pressing body 100. is there.

  In a state where the brittle material substrate W is horizontally disposed, as shown in FIG. 4, the pressing body 100 having the conical tip 101 at the lowermost end in the negative z-axis direction is negatively moved by the movement mechanism (not shown). When it is lowered in the direction, the tip portion 101 eventually comes into contact with the upper surface SF1 of the brittle material substrate W. After the contact, when the pressing body 100 is further lowered as shown by an arrow AR3 in FIG. 5, the brittle material substrate W is plastically deformed by the tip portion 101 being pushed into the brittle material substrate W, so that a recess, Indentation ID is formed. Furthermore, a large number of microcracks MC are formed around the indentation ID. In the brittle material substrate W, the microcrack MC usually has a predetermined depth with respect to the upper surface SF1 of the brittle material substrate W starting from an arbitrary position of the outer edge portion of the indentation ID (that is, in a direction perpendicular to the upper surface SF1). ) Extend. In FIG. 5, the micro crack MC is schematically shown as a hatched portion.

  In such a case, the size of the indentation ID and the length of the microcrack MC (maximum extension length) depend on the shape of the pressing body 100 and the load applied to the pressing body 100.

  The material of the pressing body 100 may be appropriately selected according to the material of the brittle material substrate W, but is preferably composed of diamond from the viewpoint of high hardness and versatility and availability. is there.

  FIG. 6 is an optical microscope image of the vicinity of the indentation ID when the indentation ID is formed on the glass substrate, which is a kind of the brittle material substrate W, using the pressing body 100 having the tip 101 having a conical shape. . However, the trench line TL is not formed. In FIG. 6, a substantially circular indentation ID is confirmed in a plan view, and it is also confirmed that a large number of microcracks MC extend randomly from the outer edge portion of the indentation ID to the outside.

  In FIG. 6, the microcracks MC seem to be formed along the upper surface of the glass substrate. However, the microcracks MC appearing on the upper surface SF1 of the glass substrate are observed in FIG. is there.

  FIG. 7 is a diagram schematically illustrating a state where the indentation ID is formed in the vicinity of the trench line TL. FIG. 8 is an optical microscope image of the vicinity of the indentation ID when the indentation ID is formed on a glass substrate which is a kind of brittle material substrate W in which the trench line TL is formed in advance.

  When the brittle material substrate W is locally pressed by the pressing body 100, as illustrated in FIG. 6, a large number of microcracks MC are randomly formed around the indentation ID. This is because, as shown in FIG. 7, in addition to the formation of the indentation ID at the location pressed by the pressing body 100, the predetermined range around the indentation ID is a region where the microcrack MC can occur. It means that it becomes the generation area RE. Here, the microcrack generation region RE is connected between the center position of the indentation ID and the position where the largest length of the microcracks MC generated along with the formation of the indentation ID reaches in the plan view. It can be considered as a region excluding the indentation ID in a circular region having a radius as a line.

  In the present embodiment, the indentation ID is formed such that the microcrack MC is generated in such a manner that it extends below the trench line TL and overlaps with the trench line TL in plan view. From another viewpoint, after forming the trench line TL in the above-described manner, the indentation ID may be formed so that a part of the microcrack generation region RE overlaps the trench line TL. I can say that. In FIG. 7, in the microcrack generation region RE, the overlapping region RE1 with the trench line TL is surrounded by a thick broken line.

When it is assumed that the indentation ID is a circle with a radius r in plan view and the microcrack generation region RE is a donut-shaped region formed with a certain width outside thereof, the radius r of the indentation ID and the micro Between the outermost radius R of the crack occurrence region RE and the distance d between the center of the impression ID and the trench line TL,
r <d <R
When this relationship holds, it can be said that a partial region of the microcrack generation region RE overlaps with the trench line TL. For the former, between the gap g between the indentation ID and the trench line TL, the radius r, the distance d, and the radius R,
g = d−r <R−r
It can be said that this relationship holds.

  When the indentation ID is formed under the condition that the microcrack generation region RE and the trench line TL are overlapped, the microcrack MC extending to the overlap region RE1 is generated with a considerable probability. When such a microcrack MC reaches the region where the residual internal stress exists immediately below the trench line TL, this triggers the release of the residual internal stress in the vicinity of the trench line TL, and the vertical crack VC from the trench line TL. The extension of. This is the details of the extension of the vertical crack VC by the method according to the present embodiment. In FIG. 8, it is observed that one microcrack MC reaches the formation location (indicated by a broken line in the figure) of the trench line TL, and the vertical crack VC progresses from the arrival location.

  Thus, the vertical crack VC can be extended from the trench line TL by forming the indentation ID in such a manner that the microcrack generation region RE overlaps with the trench line TL.

  Although FIG. 8 illustrates the case where the impression ID is formed on the left side of the trench line TL, the formation position of the impression ID may be on the right side of the trench line TL.

  When actually trying to extend the vertical crack VC by forming the indentation ID, the indentation ID may be formed so that the microcrack MC overlapping the trench line TL is surely generated. Specifically, the conditions such as the formation position of the indentation ID (distance from the trench line TL) and the load applied to the pressing body 100 when forming the indentation ID that can generate such microcracks MC are brittle. What is necessary is just to set beforehand experimentally according to the material of the material board | substrate W, thickness, etc. FIG.

  Note that it is not preferable to form the indentation ID so that the indentation ID and the trench line TL overlap. This is because the microcrack MC is not preferably generated even if the indentation ID is formed in a superimposed manner in a region that is already compressed by the formation of the trench line TL.

  FIGS. 9 and 10 are top views of the brittle material substrate W shown in FIG. 1 showing how the vertical crack VC is extended by forming the indentation ID in the brittle material substrate W formed with the trench line TL. is there.

  As shown by the arrow AR4 in FIG. 9, when the indentation ID is sequentially formed in the vicinity of the downstream side of each trench line TL arranged in the x-axis direction, each trench line as shown by the arrow AR5. Sequentially in TL, the vertical crack VC extends toward the upstream side of the trench line TL that is the expected extension direction. Eventually, as shown in FIG. 10, the extension of the vertical crack VC from the trench line TL occurs at all the dividing positions. That is, the formation of the indentation ID is a trigger (the microcrack MC extending from the indentation ID is a trigger), and until then, the brittle material substrate W that has been in a crackless state although the trench line TL has been formed. Vertical cracks VC extending from the trench line TL are formed at the respective cutting positions.

  In addition, when the trench line TL is formed using the scribe tool 150 provided with the diamond point 151, the planned extension direction of the vertical crack VC is directed to the upstream side as described above, immediately below the trench line TL. This is because the generated vertical crack VC has a property of extending to the side on the top surface SD1 side. That is, the vertical crack VC has a property of extending in a specific direction. In the present embodiment in which the trench line TL is formed in such a manner that the top surface SD1 of the diamond point is disposed on the upstream side of the trench line TL, a vertical crack is formed on the upstream side of the trench line TL when the indentation ID is formed. Although VC extends, it is difficult to extend in the reverse direction.

  Therefore, in the case illustrated in FIG. 9, the indentation ID is formed in the vicinity of the downstream side of the trench line TL, which is in the vicinity of the vertical crack VC in the trench line TL on the opposite side in the planned extension direction.

  When the vertical crack VC is extended by the method according to the present embodiment, both the processing for forming the trench line TL and the processing for forming the indentation ID cause plastic deformation to the brittle material substrate W. Since it is only generated, there is little possibility that cullet is generated in each processing. That is, according to the method according to the present embodiment, it is possible to extend the vertical crack VC without using a cullet.

  The brittle material substrate W on which the vertical crack VC is formed at the dividing position in the above manner is given to a predetermined break device (not shown). In the breaking apparatus, a bending moment is applied to the brittle material substrate W by a so-called three-point bending method or four-point bending method, thereby causing the vertical crack VC to become the other main surface (lower surface) SF2 of the brittle material substrate W (see FIG. 2). ) Is performed to extend to. By passing through the breaking step, the brittle material substrate W is divided at the dividing position.

  As described above, according to the present embodiment, after forming the trench line at the dividing position of the brittle material substrate, the indentation is locally formed in the vicinity of the trench line. By making the microcracks extending from the indentation reach below the formation position of the trench line, the vertical crack VC can be reliably generated at the dividing position of the brittle material substrate and without causing cullet. Can be extended.

<Example>
Example 1
In this example, the influence of the load applied to the pressing body 100 on the size of the indentation ID and the maximum length of the microcrack MC (hereinafter referred to as the maximum crack length) was confirmed.

  Specifically, a glass substrate having a thickness of 0.2 mm is prepared as the brittle material substrate W, and as the pressing body 100, the tip 101 has a conical shape with an opening angle of 122 ° and a radius of curvature of 10 μm. Using a certain diamond point, the indentation ID was formed by changing the load applied to the pressing body 100 to four levels of 1.3N, 2.5N, 3.8N, and 5.0N.

  FIG. 11 is a graph showing the relationship between the load and the diameter of the formed indentation ID, and FIG. 12 is a graph showing the relationship between the load and the formed maximum crack length.

  11 and 12, it is confirmed that both the size of the indentation ID and the maximum crack length tend to increase as the load increases.

(Example 2)
In this example, the influence of the load applied to the pressing body 100, the indentation ID (more specifically, the center position thereof) and the distance between the trench lines on the extension of the vertical crack VC was examined. The conditions of the pressing body 100 and the brittle material substrate W were the same as those in Example 1.

  Specifically, the load applied to the pressing body 100 is different from four levels of 1.3N, 2.5N, 3.8N, and 5.0N, and the distance between the center of the indentation and the trench line is 0 μm, ± 10 μm, By changing to nine levels of ± 20 μm, ± 30 μm, and ± 40 μm, all 36 combinations of different combinations of the load applied to the pressing body 100 and the distance between the center of the indentation and the trench line were defined. Note that the case where the distance between the center of the indentation and the trench line is negative refers to the case where the distance is positive and the case where the indentation is formed on the opposite side with respect to the trench line TL. Then, the formation of the indentation ID under each condition was performed on the brittle material substrate W in which the trench line TL having a width of about 10 μm was previously formed by the scribe tool 150.

  Table 1 shows the presence or absence of extension of the vertical crack VC from the trench line TL for all 36 patterns.

  In Table 1, “◯” is added to the column of the condition where the vertical crack VC is extended, and “X” is added to the column of the condition where the vertical crack VC is not extended.

  From the results shown in Table 1, the indentation ID is formed immediately above the trench line TL. When the distance between the indentation center position and the trench line is 0 μm, the vertical crack VC does not extend, and the indentation center position. It can be seen that the larger the distance between the trench line TL, the larger the value of the load at which the vertical crack VC extends.

  Considering the result and the result shown in Example 1, the formation position of the indentation and the load applied to the pressing body when forming the indentation are appropriately set, thereby forming the trench line TL. It can be said that the vertical crack VC can be reliably extended from the trench line TL by forming the indentation.

<Modification>
In the above-described embodiment, the case where the tip portion 101 of the pressing body 100 has a conical shape is described as an object, but the tip portion 101 of the pressing body 100 used for forming an indentation for extending a vertical crack is described. The shape is not limited to this. FIG. 13 is an optical microscope image showing a case where an indentation is formed using the pressing body 100 in which the tip 101 has a quadrangular pyramid shape and a vertical crack is extended just below the trench line TL. The result shown in FIG. 13 suggests that a vertical crack can be extended by forming an indentation under conditions corresponding to the shape of the tip portion 101 of the pressing body 100.

  Furthermore, as long as a vertical crack can be formed along with the formation of the indentation, the shape of the tip 101 need not be a cone, and may be, for example, a column.

  In the above-described embodiment, the trench line TL is formed by the scribe tool 150 in a state where the axial direction AX2 of the shank 152 is inclined toward the front of the moving direction DA, that is, the top surface SD1 is moved in the moving direction DA. This is done by sliding the diamond point 151 in a posture facing backward, but instead, in a state where the axial direction AX2 of the shank 152 is inclined toward the rear of the moving direction DA, that is, Alternatively, the trench line TL may be formed by sliding the diamond point 151 in a posture in which the top surface SD1 faces the front in the moving direction DA.

  Alternatively, in the above-described embodiment, the diamond point 151 is used to form the trench line TL, but instead, it has a disk shape (an abacus shape) and is uniform along the outer periphery thereof. The aspect which forms trench line TL may be sufficient by carrying out pressure rolling of the well-known scribing wheel provided with a blade edge in a parting position.

  However, in the case of these modes, unlike the above-described embodiment, the planned extension direction of the vertical crack is on the downstream side of the trench line TL. Therefore, in these aspects, the vertical crack VC can be extended by forming the indentation ID in the vicinity of the upstream side of the trench line TL.

DESCRIPTION OF SYMBOLS 100 Press body 101 Front-end | tip part 150 Scribe tool 151 Diamond point ID Indentation MC Microcrack RE Microcrack generation | occurrence | production area | region RE1 (A microcrack generation | occurrence | production area | region and a trench line) overlap region TL Trench line VC Vertical crack W Brittle material substrate

Claims (5)

A method of forming a vertical crack at a dividing position when dividing a brittle material substrate in the thickness direction,
A trench line forming step of forming a trench line which is a line-shaped groove on one main surface of the brittle material substrate;
An indentation forming step for forming an indentation by locally pressing the vicinity of the trench line of the brittle material substrate with a predetermined pressing body;
With
In the trench line forming step, the trench line is formed so that a crackless state is maintained immediately below the trench line,
With the formation of the indentation in the indentation formation step, by extending the microcracks extending from the indentation below the trench line, the vertical crack extends from the trench line in the thickness direction,
A method of forming vertical cracks in a brittle material substrate, characterized in that A method for forming vertical cracks in a brittle material substrate according to claim 1,
The tip of the predetermined pressing body has a conical shape,
In the indentation forming step, the indentation is formed by pressing the brittle material substrate with the conical tip.
A method of forming vertical cracks in a brittle material substrate, characterized in that A method for forming vertical cracks in a brittle material substrate according to claim 2,
The tip of the predetermined pressing body has a conical shape,
A method of forming vertical cracks in a brittle material substrate, characterized in that A method for forming a vertical crack in a brittle material substrate according to any one of claims 1 to 3,
Forming the indentation in the vicinity of the opposite side of the planned extension direction of the vertical crack in the trench line;
A method of forming vertical cracks in a brittle material substrate, characterized in that A method of dividing a brittle material substrate in the thickness direction,
A vertical crack forming step of forming a vertical crack in the brittle material substrate by the method of forming a vertical crack according to any one of claims 1 to 4,
A breaking step for breaking the brittle material substrate along the vertical crack;
A method for dividing a brittle material substrate, comprising: