JP2016221815A - Method of forming vertical crack on brittle material substrate, and method of dividing brittle material substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method capable of forming a vertical crack on a brittle material substrate with high reliability.SOLUTION: A method of forming a vertical crack onto a brittle material substrate includes: a trench line formation step to form a trench line which is a line-like groove part on one principal surface; and an assist line formation step to form an assist line crossing the trench line by rolling a scribing wheel in pressure contact comprising, on an outer periphery thereof, a blade tip on which a plurality of grooves are provided at equal intervals. In the trench line formation step, the trench line is formed so that a state of having no crack can be maintained just below the trench line. In the assist line formation step, the assist line is formed in a state where the scribing wheel is inclined at a predetermined inclination angle from a formation progress direction of the assist line in a horizontal plane. Extension of a vertical crack from the trench line is made to occur by making an intersection point of both lines a start point.SELECTED DRAWING: Figure 2

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 break process. The substrate is divided along the scribe line by causing the vertical crack to advance completely in the thickness direction by the break 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

  For example, a technique using an assist line as disclosed in Patent Document 1 is different from a technique not using this in that a scribe tool such as a cutter wheel or a diamond point is formed on a substrate when forming a scribe line for cutting. There is an advantage that the applied force (impact) can be reduced. For example, even if the scribe line is formed by applying a weak force (load) that makes it difficult to extend the vertical crack, the vertical crack can be suitably extended from the scribe line using the assist line as a trigger. is there.

  However, a high yield (reliable division) is required especially in the division of the brittle material substrate made in the production process of the mass-produced product. However, the technique disclosed in Patent Document 1 does not necessarily generate the vertical crack starting from the assist line. There is no guarantee of certainty about the extension.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a method capable of forming a vertical crack with high certainty at a predetermined dividing position of a brittle material substrate.

  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 for forming a trench line which is a groove portion, and a scribing wheel having a blade edge provided with a plurality of grooves at equal intervals on the outer peripheral portion is pressed and rolled on the one main surface to intersect the trench line. An assist line forming step for forming an assist line that is a processing mark, and in the trench line forming step, the trench line is formed so that a crackless state is maintained immediately below the trench line, and the assist line is formed. In the line forming step, the scribing wheel is The assist line is formed in a state inclined at a predetermined inclination angle from the line formation progress direction, and is perpendicular to the thickness direction of the brittle material substrate from the trench line, starting from the intersection of the trench line and the assist line. It is characterized by extending cracks.

  The invention according to claim 2 is the method for forming vertical cracks in the brittle material substrate according to claim 1, wherein in the assist line forming step, the assist line is formed inside the brittle material substrate. An internal crack region in which a large number of assist cracks exist on the side of the assist line, and the internal crack region is formed on a predetermined extension direction side of the vertical crack on the trench line. And defining a position where the assist line is formed.

  A third aspect of the invention is a method for forming a vertical crack in a brittle material substrate according to the second aspect, wherein the assist line is arranged near the trench line in the vicinity of the opposite side of the vertical extension direction of the vertical crack on the trench line. It forms so that it may cross | intersect.

  Invention of Claim 4 is the formation method of the vertical crack in the brittle material board | substrate of Claim 2 or Claim 3, Comprising: In the said assist line formation process, the advancing direction front side of the said scribing wheel is a said horizontal plane in the said horizontal plane. It is characterized in that it is inclined from the direction in which the assist line is formed toward the opposite side of the planned extension direction of the vertical crack on the trench line.

  Invention of Claim 5 is a formation method of the vertical crack in the brittle material substrate in any one of Claim 1 thru | or 4, Comprising: The said inclination | tilt angle is 1.0 degree or more and 2.5 degrees or less, It is characterized by that.

  A sixth aspect of the present invention is the method for forming a vertical crack in a brittle material substrate according to any one of the first to fifth aspects, wherein the assist line is formed after the trench line is formed. And

  The invention according to claim 7 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 6. It is characterized by comprising a vertical crack forming step and a break step for breaking the brittle material substrate along the vertical crack.

  According to the first to seventh aspects of the present invention, since the vertical crack can be extended with high certainty at the predetermined cutting position of the brittle material substrate, the brittle material substrate is reliably cut at the cutting position. It becomes possible to do.

1 is a diagram schematically showing a configuration of a scribe device 100. FIG. 2 is an enlarged view of a scribing wheel 51 in a portion A. FIG. It is a figure shown about the attitude | position of the scribing wheel 51 in the scribe apparatus 100. FIG. 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 schematically the structure of the diamond point 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 a top view of the brittle material substrate W illustrating the state when the assist line AL is formed. 4 is a top view of a brittle material substrate W illustrating how a vertical crack VC extends along with the formation of an assist line AL. FIG. 4 is a top view of a brittle material substrate W illustrating how a vertical crack VC extends along with the formation of an assist line AL. FIG. It is zx partial sectional drawing containing the vertical cross section of trench line TL and the vertical crack VC. It is a schematic diagram which shows the mode of the assist line AL vicinity at the time of the vertical crack VC being formed. This is an example of imaging a brittle material substrate W formed by forming an assist line AL with an inclination angle θ of 1.4 °. In this example, the brittle material substrate W is formed by forming an assist line AL with an inclination angle θ of 2.5 °. It is the graph which plotted VC establishment rate with respect to the load applied at the time of formation of assist line AL about each of different inclination | tilt angles (theta) of an Example. It is a top view of the brittle material substrate W in the reference example. It is the graph which plotted VC establishment rate about the reference example with respect to the load applied at the time of formation of assist line AL.

<Scribe device>
FIG. 1 is a diagram schematically showing a configuration of a scribing apparatus 100 used in the embodiment of the present invention. The scribing device 100 is generally used when a brittle material substrate W such as a glass substrate, a ceramic substrate, or a semiconductor substrate is divided in the thickness direction DT at a predetermined dividing position to reduce the size. In the embodiment, the scribing device 100 is used for forming an assist line AL (see FIG. 7 and the like) that is performed to extend a vertical crack at a cutting position on the one main surface SF1 side of the brittle material substrate W. In the present embodiment, the assist line AL is perpendicular to the trench line TL formed at a position intersecting with the trench line TL (see FIG. 4 and the like) formed at the dividing position on the main surface SF1 side. It is a processing mark that becomes a starting point (trigger) when a crack is extended. Further, the trench line TL is a fine line-shaped groove (concave portion) immediately below the trench crack TL. Details of the assist line AL and the trench line TL will be described later.

  The scribing apparatus 100 mainly includes a table 1 on which the brittle material substrate W is placed and a scribing head 2 that holds the scribing tool 50.

  The scribing apparatus 100 includes one or both of a table moving mechanism and a scribing head moving mechanism (not shown). With these mechanisms, in the scribing apparatus 100, the scribing head 2 holds the scribing tool 50. The table 1 can move relative to the horizontal plane. Hereinafter, for the sake of simplicity, it is assumed that the scribe head 2 moves relative to the table 1 in the scribe direction DP shown in FIG.

  The scribe tool 50 is a tool for scribing the brittle material substrate W. The scribe tool 50 includes a scribing wheel (cutter wheel) 51, a pin 52, and a holder 53.

  The scribing wheel 51 has a disc shape (an abacus bead shape), and includes a cutting edge PF along its outer periphery. FIG. 2 is an enlarged view of the scribing wheel 51 in the portion A shown in FIG. Macroscopically, the outer periphery of the scribing wheel 51 appears to have a uniform circular shape as shown in FIG. 1, but actually, as shown in FIG. It is provided at intervals. That is, the scribing wheel 51 is a so-called grooved wheel. In addition, the blade edge PF has a substantially triangular shape in cross-sectional view other than the groove G, which includes a ridge line and a pair of inclined surfaces sandwiching the edge line.

  The scribing wheel 51 typically has a diameter of about several millimeters, and has several hundreds of grooves G having a depth of several micrometers. The pin 52 is inserted perpendicularly to the position of the axis center AX of the scribing wheel 51. The holder 53 is held by the scribe head 2 and supports a pin 52 inserted through the scribing wheel 51 in such a manner that the scribing wheel 51 can rotate around the axial center AX. That is, the holder 53 pivotally supports the scribing wheel 51 integrated with the pin 52 so as to be rotatable around the axis center AX. More specifically, the holder 53 supports the pin 52 horizontally such that the surface formed by the cutting edge PF (outer peripheral portion) of the scribing wheel 51 extends in the vertical direction.

  The cutting edge PF is formed using a hard material such as cemented carbide, sintered diamond, polycrystalline diamond, or single crystal diamond, for example. From the viewpoint of reducing the surface roughness of the ridgeline and the inclined surface, the entire scribing wheel 51 may be made of single crystal diamond.

  In the scribing apparatus 100 having the above-described configuration, one main surface (hereinafter also referred to as an upper surface) of the brittle material substrate W that is horizontally mounted and fixed on the table 1 with the other main surface SF2 as a mounting surface. The scribing head 2 that holds the scribing tool 50 is moved in the scribing direction DP while the scribing wheel 51 is in pressure contact with SF1. Then, the scribing wheel 51 in pressure contact with the brittle material substrate W is rolled around the axis center AX in the direction indicated by the arrow RT in a state where the cutting edge PF is slightly intruded into the brittle material substrate W. Thereby, on the upper surface SF <b> 1 of the brittle material substrate W, plastic deformation along the moving direction of the scribing wheel 51 occurs with the press-contact rolling of the scribing wheel 51. In the present embodiment, the pressure rolling operation of the scribing wheel 51 that causes the plastic deformation is referred to as a scribing operation by the scribing wheel 51. The load applied to the brittle material substrate by the scribing wheel 51 when the scribing wheel 51 is pressed against the upper surface SF1 can be adjusted by a load adjusting mechanism (not shown) provided in the scribe head 2.

  FIG. 3 is a diagram illustrating the posture (inclination) of the scribing wheel 51 in the scribing apparatus 100. In the present embodiment, the scribing direction DP is a reference direction, and the scribing wheel 51 is inclined clockwise by an angle θ in the horizontal plane with respect to the scribing direction DP in a state of being held by the scribing head 2. Is defined as the inclination angle of the scribing wheel 51. The inclination angle θ is also an angle formed between the extending direction D1 of the orthogonal axis between the vertical plane formed by the cutting edge PF (ridge line) of the scribing wheel 51 and the horizontal plane and the scribe direction DP.

  In the present embodiment, as described above, the assist line AL is formed when the one brittle material substrate W is divided. The inclination angle θ at the time of forming the assist line AL is intentionally larger than 0 °. And Note that the assist line AL is formed to have a specific property by determining the inclination angle θ in such a manner, and details thereof will be described later.

  Specifically, the scribing device 100 in which the inclination angle θ is set in the range of 1.0 ° to 2.5 ° is used for forming the assist line AL.

  The inclination of the scribing wheel 51 may be realized by inclining the scribe head 2, or may be realized by changing the attachment angle of the scribe tool 50 to the scribe head 2. It may be a mode realized in other modes.

<Vertical crack formation procedure>
Next, a procedure for forming a vertical crack at the dividing position using the assist line AL performed in the present embodiment will be described. 4 to 10 are diagrams showing the state of formation of such vertical cracks in stages. 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. In each figure, the x-axis coordinate of the right-handed system in which the formation progress direction of the assist line AL is the positive x-axis direction, the formation progress direction of the trench line TL is the negative y-axis direction, and the upper vertical direction is the positive z-axis direction. It is attached.

  First, the trench line TL is formed by the scribe tool 50 in which the inclination angle θ is set to 0 °. FIG. 4 is a top view (xy plan view) of the brittle material substrate W illustrating the state after the formation of the trench line TL. FIG. 5 is a diagram schematically showing a configuration of the scribe tool 150 used for forming the trench line TL. FIG. 6 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. 4 corresponds to a dividing position when the brittle material substrate W is viewed in plan view from the 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. 5, 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. 5B, 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. For example, as shown in FIG. 5A, the diamond point 151 is held on the one end side of a shank 152 having a rod shape (columnar shape) in such a manner that the top surface SD <b> 1 is the lowest end portion.

  When the scribe tool 150 is used, as shown in FIG. 5A, 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. 4 and 6, the trench line TL is a fine line-shaped groove formed on the upper surface SF1 of the brittle material substrate W so as to extend in the y-axis direction. 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 this case, as schematically shown in FIG. 6, 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. 4, the trench line TL is formed from the start point T1 to the end point T2 in the negative 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. 4, 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, but 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. 6).

  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.

  Following the formation of the trench line TL, the assist line AL is formed by the scribing device 100 including the scribing tool 50 having the inclination angle θ set in the range of 1.0 ° to 2.5 °. FIG. 7 is a top view of the brittle material substrate W illustrating the state when the assist line AL is formed. FIGS. 8 and 9 are top views of the brittle material substrate W illustrating the extension of the vertical crack VC accompanying the formation of the assist line AL. FIG. 10 is a zx partial cross-sectional view including a vertical cross section of the trench line TL and the vertical crack VC.

  In the present embodiment, as shown in FIG. 7, the assist line AL has a start point A1 in the positive x-axis direction indicated by an arrow AR2 (so as to be orthogonal to the trench line TL) in the vicinity of the downstream side of the trench line TL. To the end point A2 are processing marks formed by causing plastic deformation on the upper surface SF1 of the brittle material substrate W.

  More specifically, the assist line AL is formed in such a manner that the formation progress direction of the assist line AL indicated by the arrow AR2 is made coincident with the scribe direction DP (x-axis positive direction). Therefore, the assist line AL is formed in a state where the front of the scribing wheel 51 in the traveling direction is tilted to the y-axis negative direction side, which is downstream of the position where the assist line AL is formed.

  In such a case, the scribing wheel 51 rolls in the scribing direction DP while the scribing wheel 51 is in pressure contact with the upper surface SF1 of the brittle material substrate W. As a result, the assist line AL is intermittently formed in the x-axis direction, and is formed as a wider processing mark as the inclination angle θ is larger (see FIGS. 12A and 13A), and the cross-sectional shape thereof is asymmetric. (See FIG. 12B). Note that the assist line AL is not formed for the purpose of extending the vertical crack immediately below the trench line TL as in the case of forming the trench line TL. The applied load can also be set to a smaller value as compared to the case where the same scribing wheel 51 is used to form a scribe line with vertical crack extension.

  When the assist line AL is formed in the above-described manner under a condition in which the load applied by the scribing wheel 51 is equal to or greater than a predetermined threshold value, the assist line AL crosses the trench line TL. As indicated by an arrow AR3 in FIG. 8, sequentially from the position of the intersection C with each trench line TL toward the expected extension direction of the vertical crack VC (in the case of FIG. 8, upstream of the trench line TL). As shown in FIG. 10, the extension of the vertical crack VC from the trench line TL to the thickness direction DT of the brittle material substrate W occurs.

  Eventually, as shown in FIG. 9, the extension of the vertical crack VC from the trench line TL occurs at all the dividing positions. That is, triggered by the formation of the assist line AL (triggered by the assist line AL), until the trench line TL has been formed, the crack-less state of each of the brittle material substrates W has been divided. A vertical crack VC extending from the trench line TL is formed.

  This is because when the scribe tool 150 having the diamond point 151 is used to form the trench line TL, the vertical crack VC generated immediately below the trench line TL has a property of extending to the side where the top surface SD1 exists. is there. That is, the vertical crack VC generated in the vicinity of the assist line AL 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 arranged on the upstream side of the trench line TL, after the assist rain AL is formed, it is vertical on the upstream side of the trench line TL. Although the crack VC extends, it is difficult to extend in the reverse direction.

  In this manner, the brittle material substrate W on which the vertical crack VC is formed at the dividing position is given to a predetermined break device (not shown). In the break device, a break process for extending the vertical crack VC to the lower surface SF2 of the brittle material substrate W is performed by applying a bending moment to the brittle material substrate W by a so-called three-point bending or four-point bending method. . By passing through the break process, the brittle material substrate W is divided at the dividing position.

  In the case of the above procedure, since the formation of the trench line TL at the dividing position is not accompanied by the extension of the vertical crack VC, the vertical crack is formed at the same time as the scribe line is formed. There is an advantage that the load applied to the scribe tool 50 can be reduced as compared with the case where it is performed. Such an advantage contributes to extending the life of the scribe tool 50 used for cutting at the cutting position.

<Details of vertical crack extension>
FIG. 11 is a schematic diagram showing a state in the vicinity of the assist line AL when the vertical crack VC is formed by forming the assist line AL following the formation of the trench line TL. 12 and 13 are examples of imaging of the brittle material substrate W formed with the assist lines AL. FIG. 12 is an example of imaging when the tilt angle θ is 1.4 °, and FIG. 13 is an example of imaging when the tilt angle θ is 2.5 °.

  When the assist line AL is formed in the x-axis positive direction (in the direction perpendicular to the y-axis), which is the scribe direction DP, the y-axis direction positive side inside the brittle material substrate W (see FIG. 11) throughout the formation position. In FIG. 3, an internal crack region CR in which innumerable assist cracks starting from the assist line AL exist is formed on the side of the assist line AL, which is on the upper side of the assist line AL in the drawing). This is also confirmed, for example, in FIGS. 12A and 13A in which the brittle material substrate W is observed from the side of the upper surface SF1.

  More specifically, the internal crack region CR is generated in an unevenly distributed manner within a range from the (+ y, −z) direction to the −z direction starting from an arbitrary position of the assist line AL. This is also confirmed from FIG. 12 (b) and FIG. 13 (b). The internal crack region CR is formed in a range of about several tens of μm at most from the assist line AL in the positive y-axis direction than the assist line AL when the upper surface SF1 is viewed in plan. However, although illustration is omitted in FIG. 11, since the formation of assist cracks is a phenomenon that occurs stochastically, assist cracks are also generated in other ranges although the ratio is small.

  Since the internal crack region CR is formed over the entire assist line AL, the internal crack region CR is generated with a high probability even in the vicinity of the location where the assist line AL intersects the trench line TL. As described above, since internal stress remains in the vicinity of the trench line TL, the assist line is formed so that the internal crack region CR is formed on the side of the vertical extension VC of the trench line TL in the predetermined extension direction. In this case, the internal crack region CR is formed in the region where the residual internal stress exists, and the residual internal stress is released in the vicinity of the trench line TL. As a result, as indicated by an arrow AR4 in FIG. 11B, the vertical crack from the trench line TL is directed toward the planned extension direction of the vertical crack VC (upstream of the trench line TL in the present embodiment). VC stretching occurs. This is the details of the extension of the vertical crack VC by the method according to this embodiment described above.

  Moreover, in the method according to the present embodiment, as described above, the assist line AL is formed by using the scribing wheel 51 that is intentionally inclined with the inclination angle θ of 1.0 ° to 2.5 °. The internal crack region CR is unevenly distributed on the side opposite to the side where the scribing wheel 51 is inclined forward in the traveling direction, and the dividing position extends on the side where the internal crack region CR is formed. The formation positions of the assist line AL and the trench line TL are set. Thereby, the certainty of extension of the vertical crack VC from the trench line TL at the dividing position is enhanced. That is, the formation of the assist line AL using the intentionally inclined scribing wheel 51 employed in this embodiment limits the extension location of the vertical crack VC and increases the certainty of the extension. It has become. That is, when the brittle material substrate W is divided, the direction of the inclination of the scribing wheel 51, the formation position of the assist line AL, and the formation position of the trench line TL are determined according to the division position. The vertical crack VC can be reliably extended.

  In addition, when θ is smaller than 1.0 °, the uneven distribution of the internal crack region CR does not occur, and the reliability of crack extension decreases, which is not preferable. Further, as the inclination angle θ increases, rolling of the scribing wheel 51 when forming the assist line AL becomes more difficult, and cullet tends to be easily generated.

  As described above, according to the present embodiment, when the brittle material substrate is divided at a predetermined dividing position, the vertical crack is not generated immediately below the forming position corresponding to the dividing position. Of the assist line in a mode in which the assist crack is unevenly distributed on the upstream side of the trench line, which is the planned extension direction of the vertical crack VC, using a scribing wheel intentionally inclined in a horizontal plane. By performing the formation, the vertical crack can be extended with high certainty at the dividing position. When the vertical crack is reliably formed, the brittle material substrate can be reliably cut at the cutting position in a break process as a subsequent process. In such a case, the load applied by the scribing wheel when forming the trench line and the assist line can be set to a value smaller than that in the case of performing a scribe operation accompanied by vertical crack extension.

<Example>
The trench line TL and the assist line AL were formed a plurality of times while changing the assist line AL formation conditions by the procedure shown in the above-described embodiment, and the occurrence of the vertical crack VC extension was evaluated. As the brittle material substrate W, a glass substrate having a thickness of 0.3 mm was used.

  Specifically, the assist line AL differs in the inclination angle θ from three levels of 1.4 °, 2.5 °, and 4.9 °, and loads applied to the scribing wheel 51 are 0.75N, 1.1N, 1 It was formed under a total of 21 conditions by changing to 7 levels of 5N, 1.9N, 2.25N, 2.6N, and 3.0N. The moving speed of the scribe head 2 was 100 mm / sec. As the scribing wheel 51, the wheel diameter is 1.8 mm, the thickness is 0.65 mm, the diameter of the insertion hole of the pin 52 is 0.8 mm, the blade edge angle is 100 °, the number of grooves G is 300, A depth of 3 μm was used.

  In addition, the trench line TL was formed by fixing 100 loads applied to the scribe tool 150 and forming 100 lines for each formation condition of the assist line AL.

  FIG. 14 shows the load applied at the time of forming the assist line AL with the occurrence rate of vertical crack VC from all 100 trench lines TL (hereinafter referred to as VC establishment rate) for each of the three inclination angles θ. Is a graph plotted against.

  As shown in FIG. 14, when the inclination angle θ is 1.4 °, a VC formation rate of 90% or more is obtained when the load applied to the scribing wheel 51 is 1.1 N or more, and the inclination angle θ is 2 In the case of .5 °, a VC formation rate of 95% or more was obtained by setting the load applied to the scribing wheel 51 to 1.5 N or more. On the other hand, when the inclination angle θ is 4.9 °, the VC establishment rate is about 90% at the maximum.

  These results show that when the inclination angle θ is 1.4 °, a load of at least 1.1 N is applied to the scribing wheel 51, and when the inclination angle θ is 2.4 °, the scribing wheel 51 This indicates that the vertical crack VC can be extended from the trench line TL with a high probability if a load of at least 1.5 N is applied to. It is also shown that the vertical crack VC can be extended even if the inclination angle θ is further increased, but the certainty is low.

  In addition, if the scribing operation is performed using the scribing wheel 51 under the same conditions and the vertical crack is extended along with the formation of the scribe line, it is necessary to apply a load of at least about 3 to 4N. The result of the example also shows that the assist line AL can be formed by applying a load smaller than the load applied by the scribing wheel 51 during the scribing operation accompanied by the extension of the vertical crack. Furthermore, since the trench line TL can be formed by applying a load that is equal to or smaller than that of the assist line AL, the method according to the above-described embodiment is directly applied to the vertical crack by the scribe operation. It can be said that it is a technique that enables the extension of vertical cracks by applying a low load compared to the technique of extending the crack.

<Modifications and reference examples>
In the above-described embodiment, the assist line AL is formed after the trench line TL is formed. However, the formation order of the trench line TL and the assist line AL may be reversed.

  In the above-described embodiment, the trench line TL and the assist line AL are orthogonal to each other on the upper surface SF1 of the brittle material substrate W, but this is not an essential aspect, and the trench line associated with the formation of the assist line AL. As long as the extension of the vertical crack from the TL is suitably realized, the trench line TL and the assist line AL may be obliquely intersected.

  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. However, instead of this, the trench line TL may be formed by pressing and rolling the scribing wheel. Good. In this case, as the scribing wheel, it is preferable to use a scribing wheel that is not provided with a groove on the cutting edge. This includes, for example, a scribing device 100 for forming a trench line TL having a scribing wheel without grooves, and an assist having a scribing wheel 51 whose inclination angle θ is fixedly set in a range of 1.0 ° to 2.5 °. This is realized by separately preparing the scribing device 100 for forming the line AL and forming the trench line TL and the assist line AL using each of them.

  However, in the case of the latter two aspects, 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 upstream vicinity assist line AL of the trench line TL is formed while the scribing wheel 51 is inclined so that the inclination angle θ is negative. More specifically, the assist line AL may be formed in a state where the front in the traveling direction of the scribing wheel 51 is inclined to the y-axis negative direction side downstream from the position where the assist line AL is formed.

  Also in this case, as in the above-described embodiment, the assist line AL is formed in a manner in which the assist crack AC is unevenly distributed on the downstream side of the trench line TL that is the expected extension direction of the vertical crack VC. In the planned extension direction, vertical crack extension from the trench line TL preferably occurs. As a result, the vertical crack can be extended with high certainty at the dividing position where the trench line TL is formed.

  FIG. 15 is a top view of the brittle material substrate W shown as a reference example when the trench line TL and the assist line AL are formed in a different positional relationship from the above-described embodiment. Specifically, in the case shown in FIG. 15, after forming the trench line TL in the y-axis positive direction, the assist line AL is placed near the end on the y-axis direction positive side of the brittle material substrate W by the arrow AR2β. As shown in the figure, it is formed in the positive x-axis direction. In such a case, contrary to the above-described embodiments and examples, the assist line AL is formed in a state in which the front of the scribing wheel 51 in the traveling direction is tilted to the upstream side of the position where the assist line AL is formed. . In other words, the assist line AL is formed so that the forward direction of the scribing wheel 51 is on the same side as the extending direction of the trench line TL. Therefore, in this case, if the extension of the vertical crack VC from the trench line TL occurs due to the formation of the assist line AL, it is in the direction indicated by the arrow AR3β, that is, from the intersection C of the trench line TL and the assist line AL. This occurs in the direction toward the upstream side of the line TL.

  FIG. 16 is obtained by evaluating the VC establishment rate for the reference example by changing the inclination angle θ to three levels of 1.4 °, 2.5 °, and 4.9 °, as in the above-described example. It is the graph which plotted VC establishment rate with respect to the load applied at the time of formation of assist line AL.

  As shown in FIG. 16, in the reference example, when the inclination angle θ is 2.5 °, a VC establishment rate of 95% or more can be obtained when the load applied to the scribing wheel 51 is 1.9 N or more. When the inclination angle θ is 4.9 °, the load applied to the scribing wheel 51 is set to 1.9 N or more, and a VC establishment rate of 100% is obtained. On the other hand, when the inclination angle θ is 1.4 °, the VC establishment rate exceeds 90% only when the load is 3.0 N.

  That is, the relationship between the inclination angle θ and the VC establishment rate in the reference example is opposite to the relationship in the above-described embodiment. In addition, when the inclination angle θ is 2.5 °, it was confirmed that there is a load range in which the vertical crack VC can be extended with high probability in both the example and the reference example. This means that the formation position of the internal crack region CR (relationship with the formation position of the assist line AL) depends on the value of the inclination angle θ, and therefore depends on the inclination angle θ. This suggests the possibility of controlling the direction in which the vertical crack VC extends. However, as described above, when the value of the inclination angle θ is increased, cullet is likely to be generated. Therefore, in practice, the inclination angle θ is 1.0 ° -2. It is preferable to define within a range of 5 °.

1 Table 2 Scribe head 50, 150 Scribe tool 51 Scribing wheel 52 Pin 53 Holder 100 Scribe device 151 Diamond point 152 Shank A1 (Assist line TL) start point A2 (Assist line TL) end point AL Assist line AX Axis center C (Trench Intersection of line TL and assist line AL CR internal crack region DP scribe direction PF (cutting wheel 51) cutting edge SF1 (brittle material substrate W) one main surface (upper surface)
SF2 (of brittle material substrate W) other main surface (lower surface)
T1 Start point (of the trench line TL) T2 End point (of the trench line TL) TL Trench line VC Vertical crack W Brittle material substrate

Claims (7)

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 assist line forming step of forming an assist line which is a processing mark intersecting the trench line by pressing and rolling a scribing wheel having a blade edge provided with a plurality of grooves at equal intervals on the outer peripheral portion on the one main surface; ,
With
In the trench line forming step, the trench line is formed so that a crackless state is maintained immediately below the trench line,
In the assist line forming step, the assist line is formed in a state where the scribing wheel is inclined at a predetermined inclination angle from a direction in which the assist line is formed in a horizontal plane,
Extending a vertical crack from the trench line in the thickness direction of the brittle material substrate starting from the intersection of the trench line and the assist line,
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,
In the assist line forming step, along with the formation of the assist line, an internal crack region in which a large number of assist cracks exist in the side of the assist line inside the brittle material substrate is generated,
The formation position of the trench line and the assist line is determined so that the internal crack region is formed on the planned extension direction side of the vertical crack on the trench line.
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,
Forming the assist line so as to intersect the trench line in the vicinity of the opposite side of the planned extension direction of the vertical crack on the trench line;
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 claim 2 or 3,
In the assist line forming step, the front side in the traveling direction of the scribing wheel is inclined from the direction in which the assist line is formed in the horizontal plane toward the opposite side of the planned extension direction of the vertical crack on the trench line.
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 4,
The inclination angle is 1.0 ° to 2.5 °,
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 5,
Forming the assist line after forming 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 6,
A breaking step of breaking the brittle material substrate along the vertical crack;
A method for dividing a brittle material substrate, comprising: