JP2009090598A - Curved crack-forming method of brittle material substrate, and brittle material substrate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of forming a crack along a curved possible dividing line. <P>SOLUTION: Covering means ML and MR mounted on the surface of the substrate have a band-like opening area R whose central line coincides with the possible dividing line CL, and shield the surface of the substrate other than the opening area so that a heat spot does not pass the same area when the heat spot HS is relatively moved along the possible dividing line. The heat spot HS having a wider width than the lateral width Wo of the opening area is relatively moved along the possible dividing line CL to cover a part of the opening area. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method of forming a curved crack in a brittle material substrate. More specifically, the present invention relates to heating by irradiating a laser beam while moving relatively along a curved segmentation scheduled line set in the brittle material substrate. Then, the present invention relates to a method of forming a crack in the substrate by using the stress generated in the substrate at this time by cooling.

Here, the brittle material includes materials such as ceramics, single crystal silicon, a semiconductor wafer, and sapphire in addition to the glass substrate.
In addition, the crack is a crack that penetrates from the front surface to the back surface of the substrate, and when the substrate is divided at once by the crack (called full cut), it is a crack that is shallowly formed near the surface of the substrate. The case where the scribe line is formed without being completely divided (referred to as scribe) is included.

  When cutting a brittle material substrate such as a glass substrate, as a processing method that can obtain a sectional surface with excellent quality, local heating by laser irradiation at a temperature below the softening point of the substrate, followed by cooling, the substrate A method of forming a crack starting from an initial crack formed in advance on the edge of a substrate by generating a stress gradient in the substrate has been put into practical use.

  In general, a crack forming method by laser irradiation is often used when a substrate is divided along a straight line to be divided. Therefore, in order to make the laser beam heating spot (irradiation cross section of the laser beam irradiated on the substrate surface) symmetric with respect to the linearly scheduled dividing line, and to heat it more efficiently, the direction of the scheduled dividing line is set. The heating spot is an ellipse or oval with a long axis.

  For example, a circular cooling spot formed by forming an elliptical heating spot with a focusing lens or the like, moving the heating spot relative to the dividing line set on the substrate, and then ejecting a coolant from the nozzle, A method is disclosed in which cracks are linearly formed and divided by relative movement so as to follow the trajectory through which the heating spot has passed (see Patent Document 1).

  According to another document, the substrate is laser-heated while moving the laser irradiation position along the set dividing line, and the compressive stress generated near the heat source (irradiation part) and the vicinity of the heat source (irradiation part) It is disclosed that the substrate is divided using the tensile stress generated in (see Patent Document 2). That is, it is disclosed that, after laser irradiation, the substrate is cut by a stress distribution due to natural cooling of the substrate without positively injecting the coolant and forcibly cooling.

  On the other hand, depending on the application of the glass substrate or the like, for example, when the substrate is processed into a circle, or when the substrate is processed into a rectangle and the corners of the four corners are rounded, the substrate is to be cut out along a curved shape. There is a case. At this time, it is necessary to set a curve-shaped division planned line and move a heating spot or a cooling spot along this line to form a crack.

  When forming a crack along a curved dividing line, use a heating spot (for example, an elliptical heating spot) or a cooling spot that is the same as that used when dividing a line, along a curved dividing line. When these are moved, there may occur a positional shift phenomenon in which a crack is formed at a position deviated from the planned dividing line (see FIG. 5C of Patent Document 2).

  FIG. 14 is a diagram showing a typical example of the positional deviation that occurs between the planned dividing line CL and the crack CR that is actually formed when the heating spot and the cooling spot are moved along the curved dividing planned line. is there. In this case, the generated crack CR overshoots the line to be divided CL. This positional shift is due to the fact that the heat distribution generated on the substrate becomes asymmetrical on the left and right of the planned dividing line CL when the heating spot HS and the cooling spot CS are moved along the planned dividing line CL.

  One of the reasons why the heat distribution becomes asymmetrical on the left and right of the division line CL is usually because the laser that creates the heating spot HS and the refrigerant injection nozzle that creates the cooling spot CS move while maintaining the mutual positional relationship. . In this case, when the heating spot HS and the cooling spot CS are simply moved along the linearly scheduled dividing line, the locus of both spots can be on the same scheduled dividing line CL. However, when trying to move along the cut-scheduled line CL having a curved shape, it is difficult to match the trajectory through which the heating spot HS passes with the trajectory through which the cooling spot CS passes.

  FIG. 15 is a diagram illustrating an example of the locus of the heating spot HS and the locus of the cooling spot CS when the heating spot HS is moved along the curve-shaped division schedule line CL. Here, the center of the elliptical heating spot HS (indicated by a white circle in the figure) is moved along the scheduled dividing line CL. The cooling spot CS is assumed to be circular, and the center of the circle (indicated by a black circle in the figure) is located at a position away from the center of the ellipse by a predetermined distance L.

  In this case, when the center of the heating spot HS is moved along the division line CL, a line connecting the center of the heating spot and the center of the cooling spot (that is, the major axis direction of the ellipse) is the line to be divided. When the heating spot HS advances while rotating so as to be in the tangential direction, the center of the cooling spot CS moves outside the line to be cut CL.

  As a result, a crack is formed at a position deviated from the planned dividing line CL through which the center of the heating spot HS passes, and an overshoot occurs. This overshoot phenomenon becomes more prominent as the radius of curvature of the curve shape of the division line CL becomes smaller.

  The second reason that the heat distribution becomes asymmetrical is that when the heating spot HS is moved along the cut line CL having a curved shape, the heating peak position in the heating spot HS increases as the moving speed of the heating spot HS increases. This is because (the position heated to the highest temperature) shifts backward due to a time lag due to thermal relaxation.

FIG. 16 is a diagram showing the heating peak position HS _{T at} which the temperature becomes highest for the heating spot HS that is stopped and moving. The heating spot HS is elliptical, and as shown in FIG. 16A, the energy density of the laser beam is adjusted so that the heating peak position HS _T is at the center of the heating spot HS in the stop state. (For example, Gaussian distribution). Even if such a heating spot HS is moved, due to the time lag due to thermal relaxation, as shown in FIG. 16B, the peak position HS _T of the heating during the movement is apparently the position of the heating spot HS. It will shift slightly backward from the center. That is, the heat spot HS in moving, apparently will be heated as being a distance ΔL by heating peak position HS _T at a position shifted backward from the center. Since this shift amount ΔL varies depending on the moving speed of the heating spot HS with respect to the substrate, it is difficult to specify the heating peak position HS _T in the moving heating spot HS.
Therefore, moving to center of the heat spot HS passes directly over division planned line CL of the curved shape, the trajectory of the heating of the peak position HS _T will be deviated from the cutting-scheduled line CL, the formation of cracks The position to be deviated from the division planned line CL.

In the above description, the case where the heating peak position HS _T in the stopped state is at the center of the heating spot HS (Gaussian distribution or the like) has been described. However, the peak position HS _{T in} the stopped state of the heating spot HS can be found anywhere. Regardless of the shape of the heating spot HS, if the heating spot HS moves, it will shift backward due to the time lag due to thermal relaxation, so it predicts the heating peak position during movement and passes on the planned dividing line It is difficult to make it.

  In an actual substrate, misalignment due to these two reasons occurs in combination. In this way, when forming a crack along a curved line to be divided, the conventional method of forming a crack by moving a heating spot or moving a heating spot and a cooling spot, which has been performed for a linear shape, is used as it is. By simply applying it, it sometimes deviated from the planned dividing line.

On the other hand, a method capable of accurately dividing along a curve-shaped dividing line is disclosed (see Patent Document 3). According to this, the shape of the “linear focal point” of the laser beam can be adjusted according to the contour of each part of the curved line to be divided (free-form dividing line), and the irradiation position of the laser beam can be moved. If the curvature of the line to be cut changes as a result, the curved shape of the “linear focus” is adjusted accordingly, and laser irradiation is performed so that the “line focus” is maintained on the line to be cut. . Further, the position of the cold spot (cooling spot) is guided while being adjusted along the “linear focus”. Therefore, any shape can be divided.
Japanese Patent No. 3027768 Japanese Patent No. 3498895 Special table 2003-520682 gazette

It is possible to divide a glass substrate or the like along a desired curved shape using a crack forming method by laser irradiation by the method described in Patent Document 3 described above.
However, in order to divide the substrate by this method, a reference point that represents the position of the entire linear focal point (usually, the central position of the linear focal point is used as a reference point) along the scheduled dividing line is used. In addition to the need for a program, it is necessary to form a program that changes the shape of the linear focal point in accordance with the curved shape of each part of the line to be divided. Furthermore, a program for adjusting the length of the linear focus in accordance with the curvature radius of the curve is required so that the length of the linear focus becomes shorter as the curvature radius becomes smaller.

Thus, it is necessary to prepare a complicated control program. Furthermore, if the curved shape and the linear focal point are not accurately aligned when irradiating the laser, a positional deviation between the curved shape and the linear focal point will occur, and the shape will be separated from the line to be separated. Will be.
In addition, it is necessary to provide a cold spot (cooling spot) adjusting mechanism and adjust the position of the cold spot (cooling spot) in correspondence with the linear focal point.

  Therefore, the present invention provides a simple heating spot without preparing a program for changing the shape of the linear focus in each part of the curved shape or a program for adjusting the length of the linear focus according to the radius of curvature. Another object of the present invention is to provide a method in which a cooling spot can be used and a crack can be formed along a curved dividing line.

  A first crack forming method made to solve the above-described problem is to set a curve-shaped dividing line for a substrate made of a brittle material, and to set a heating spot formed by a laser beam along the dividing line. And forming a crack in the brittle material substrate by forming a crack in the substrate by heating at a temperature equal to or lower than the softening point. And a covering means for shielding the heating spot from passing over the substrate surface other than the opening region when the heating spot is relatively moved along the division line, and provided on the substrate surface, from the lateral width of the opening region A wide heating spot is formed, and this heating spot covers a part of the opening area and moves relative to the line to be divided.

  Further, a second crack forming method made to solve the above-mentioned problem is to set a curved dividing line for a substrate made of a brittle material, and to set a heating spot formed by a laser beam to the dividing line. A brittle material substrate that is heated at a temperature equal to or lower than the softening point and then moved at a temperature equal to or lower than the softening point and then relatively moved along the planned dividing line to form a crack in the substrate. A method of forming a crack, wherein the substrate has a band-shaped opening region whose center line coincides with the planned dividing line, and the heating spot and the cooling spot are moved relative to each other along the planned dividing line. Covering means is provided on the surface of the substrate to shield the heating spot and cooling spot from passing over the surface and is wider than the lateral width of the opening area. A heating spot is formed, and the heating spot covers a part of the opening area and is relatively moved along the line to be divided, thereby forming a cooling spot wider than the lateral width of the opening area. Immediately after the heating spot has passed, the relative movement is made along the planned dividing line while covering the portion.

  Here, the laser beam may be a laser light source that can absorb and heat a laser beam when irradiated on a brittle material substrate, such as a carbon dioxide laser, excimer laser, YAG laser, carbon monoxide. An appropriate light source may be used from a laser or the like according to the brittle material substrate. Specifically, for example, in the case of a glass substrate, a carbon dioxide laser can be used.

  In addition, the shape of the irradiation surface of the heating spot and the injection surface of the cooling spot is wider than the width of the opening area, and may be a simple shape such as a circle or an ellipse as long as it can move while covering a part of the opening area, Any shape is acceptable.

  According to the first crack forming method, the covering means is provided on the substrate surface of the brittle material substrate. This covering means has a band-shaped opening area, and the center line of the opening area is set along a curve-shaped parting line. The covering means shields the substrate surface so that the heating spot is not irradiated on the substrate surface except in the opening region when the heating spot formed by the laser beam moves along the line to be cut. On the other hand, the heating spot is formed wider than the lateral width of the opening area (opening width in the direction perpendicular to the center line). By moving the heating spot along the planned dividing line, the heating spot is changed to the planned dividing line. As it moves along, the band-like open area is evenly heated. At this time, a part of the heating spot also passes outside the opening region, but the coating means prevents direct irradiation onto the substrate, and as a result, the influence of heating is almost less than that of the opening region. Therefore, the inside of the opening area is heated almost evenly. As a result, thermal stress is formed along the center line of the opening area, that is, the planned dividing line, and cracks are formed along the planned dividing line. Is done.

  Further, according to the second crack forming method, in the first crack forming method, immediately after the heating spot is relatively moved along the scheduled dividing line and heated, the cooling spot is further aligned along the scheduled dividing line. Move. At this time, the cooling spot is also made wider than the lateral width of the opening region. As a result, when the heating spot moves along the line to be divided, the band-shaped opening area is uniformly heated, and then the opening area is rapidly cooled uniformly by the cooling spot. At this time, a part of the heating spot and the cooling spot also pass outside the opening region, but the covering means prevents the direct heating spot irradiation to the substrate and the direct injection of the cooling spot to the substrate. In comparison with the opening area, the influence of heating and cooling is almost eliminated. Therefore, after heating is performed almost evenly along the opening area, it is rapidly cooled, and as a result, a large thermal stress is formed along the center line of the opening area, i.e., the planned dividing line, in the planned dividing line. A crack is formed along.

According to the first crack forming method described above, a simple shaped heating spot is formed, and according to the second crack forming method, a simple shaped heating spot and a cooling spot are formed and divided. Only by moving along the planned line, a curved crack along the curved segmented planned line can be formed.
In addition, since the heating spot and the cooling spot only need to be able to move while covering a part of the opening region, it is not necessary to perform alignment with high accuracy with respect to the planned dividing line.

(Means and effects for solving other problems)
In the above invention, the covering means may comprise a coating formed on the substrate surface. Specifically, any material that is formed on the substrate surface as an electrode film, a resist film, various protective films, and various functional films may be used as long as it does not transmit laser light. According to this, a coating film can be easily formed on the surface of the substrate by coating or by an existing thin film forming technique such as vacuum deposition or sputtering.

Further, the coating reflects a laser beam of a heating spot that passes over the coating, and when the cooling spot passes over the coating, a metal film (for example, aluminum, silver, gold) that diffuses the cold heat generated by the refrigerant by heat conduction, A transparent conductive film (for example, ITO film or SnO ₂ film) is preferred.
According to this, even if a part of the heating spot is irradiated to the metal film or the transparent conductive film which is a coating, or a part of the cooling spot is jetted, the metal film or the transparent conductive film is applied to the substrate. Heat transfer can be efficiently and effectively prevented.

Further, the brittle material substrate is formed with a functional film region made of a metal film or a transparent conductive film for generating a function in a part of the substrate, and the coating is a functional film region when the functional film region is formed. It may be formed simultaneously using the same material.
According to this, when the functional film is formed on the brittle material substrate, it is possible to simultaneously form a film using the same material as the functional film, so that it is not necessary to add a process for forming the film.

In the above invention, the covering means may be made of a sheet member placed on or fixed to the surface of the substrate.
According to this, by mounting or fixing the sheet member on the substrate surface, it is possible to easily attach the covering means to the substrate surface and shield the laser beam.

The sheet member may be made of a metal mask or a tape that reflects the laser beam of the heating spot that passes over the sheet member and diffuses the cold heat generated by the refrigerant by heat conduction when the cooling spot passes over the sheet member. Good.
According to this, even if a part of the heating spot is irradiated on the metal mask or the metal tape, or a part of the cooling spot is jetted, the substrate can be obtained by the metal mask or the metal tape. It is possible to efficiently and effectively prevent the heat transfer to.

The sheet member includes a left sheet member disposed on the left side of the opening region, a right sheet member disposed on the right side of the opening region, and a plurality of connecting portions that connect the left sheet member and the right sheet member on the opening region. Each connecting portion is configured such that when the heating spot and the cooling spot pass, the left sheet member and the right sheet member are connected with a vertical width that does not hinder the progress of cracks immediately below each connecting portion. Also good.
According to this, since the left and right sheet members can be integrated by connecting the left and right sheet members by the connecting portion, it is not necessary to align the left and right sheet members. In addition, each connecting portion is configured such that when the heating spot and the cooling spot pass, the left sheet member and the right sheet member are connected with a narrow width so that the progress of cracks is not hindered immediately below each connecting portion. Therefore, it does not affect the progress of cracks.

  The vertical width of each connecting portion is preferably 0.1 mm to 2 mm. By setting the vertical width of the opening region within this range, the connecting portion can be prevented from obstructing the progress of the crack.

The lateral width of the opening region is preferably 0.1 mm to 2 mm.
According to this, by setting the lateral width of the opening region within this range, it is possible to form a crack along the planned dividing line at the center line of the opening region with the accuracy required for practical use.

In addition, a laser beam having a wavelength that is absorbed from the substrate surface to the inside may be used, and the laser beam may be incident on the substrate obliquely along a curved dividing line.
According to this, when performing the punching process along the curved shape, the draft can be easily formed.

Further, the brittle material substrate of the present invention made from another point of view has a curve-shaped segmentation planned line, and a coating is formed on the substrate surface so as to form a strip-shaped opening region with the segmentation planned line as a center line. ing.
According to this, a heating spot wider than the width of the band-shaped opening area, or a heating spot and a cooling spot are formed, and the band-shaped opening area is uniformly heated and cooled by moving on the opening area. It becomes like this. Therefore, the substrate surface inside the opening region is heated and cooled almost uniformly, and as a result, thermal stress is formed along the center line of the opening region, that is, the planned dividing line, and along the planned dividing line. Cracks are formed.

  In the substrate, the lateral width of the opening region is preferably 0.1 mm to 2 mm. According to this, by setting the lateral width of the opening region within this range, it is possible to form a crack along the planned dividing line at the center line of the opening region with the accuracy required for practical use.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, although the following embodiment demonstrated the case where a curved crack is formed in a glass substrate, it is applicable also when forming a crack in another brittle material board | substrate.

(Embodiment 1)
FIG. 1 is a plan view of a glass substrate in each step of a curved crack forming method according to an embodiment of the present invention. 2 is a cross-sectional view taken along line AA ′ in FIGS. 1B, 1C, and 1D. A method of forming a curved crack in a glass substrate will be described with reference to FIGS. Here, a case where a circular substrate is cut out will be described as an example.

(Board preparation process)
First, a rectangular glass substrate G is prepared as a processing substrate (FIG. 1A). Markers Gm and Gn for positioning are formed in advance on the glass substrate G, and are used as reference points for processing. Further, a division line CL is set on the glass substrate G. The division line CL is a virtual line indicating the position of the crack to be formed, and the shape and position (coordinates) of the division line CL with respect to the substrate G are accurately determined. Therefore, the shape and position of the parting planned line CL with respect to the markers Gm and Gn of the processing reference point are uniquely determined.

Incidentally, pull up be cut line CL, as shown in FIG. 1 (a), a circular portion CL ₁ to be the external shape of the circular substrate to be Kiridaso, contact from one side of the substrate G at the beginning circular portion CL ₁ made from the linear portion CL ₀ Metropolitan withering. The straight line portion CL ₀ is used to guide the crack to the circular portion CL ₁ by advancing the crack from an initial crack TR (FIG. 1C) described later.

(Film formation process)
Subsequently, metal films MR and ML are formed on the surface of the glass substrate G as a film for reflecting the laser light leaving the opening region R (FIG. 1B). As the metal films MR and ML, for example, an aluminum film is used, and a pattern is formed by a sputtering method or the like. That is, a patterning mask (not shown) for covering a belt-like portion (a portion that will later become the opening region R) having the dividing line CL as a center line is placed on the substrate G. At this time, alignment between the substrate and the mask is performed by markers (not shown) provided on the patterning mask and the markers Gm and Gn of the substrate G. Then, by performing film formation by sputtering or the like after the alignment is completed, the metal films MR and ML are formed on the surface of the substrate G leaving the opening region R.

  The lateral width (width across the opening region) of the opening region R formed by the patterning mask is set in the range of 0.1 mm to 2 mm. If the width of the open region R is too small than this range, cracks are difficult to be formed due to insufficient heating, and if the width is too large, the position error between the position of the crack and the planned dividing line CL (center line) may be noticeable. become.

  In this embodiment, an aluminum film is used as the coating material, but the laser beam used for heating can be reflected, and the heat at the time of laser irradiation and the cold at the time of refrigerant injection can be diffused by heat conduction. As long as it is a material, a transparent conductive film such as another metal film or ITO film may be used. These other coatings can also be formed by a well-known coating forming technique such as sputtering, vapor deposition, or coating. Further, in this embodiment, the entire surface of the substrate is covered with a film while leaving the opening region R. However, the laser beam is not covered by partially covering the vicinity of the opening region R irradiated with the laser light. You may expose the part which is not irradiated.

(Crack formation process)
Subsequently, after the initial crack TR is formed on the end face of the substrate G, the heating spot HS by the laser beam is moved from the initial crack TR along the planned split line CL (straight line portion CL ₀ ) (FIG. 1C). Initial crack TR is formed by pressing a cutter wheel 18 described later crack forming apparatus LS1 (FIG. 3), the position of the starting point P ₀ of the cutting-scheduled line CL. The shape and size of the heating spot HS are adjusted by an optical holder 14 that incorporates an adjustment mechanism for adjusting the irradiation light from the laser 13 in a crack forming apparatus LS1 described later. As shown in FIG. 2, the width Wh that the heating spot HS irradiates the substrate G (including part of the metal films MR and ML) is wider than the lateral width Wo (width across the opening region R) of the opening region R. Thus, the heating spot HS is adjusted so that the irradiation range of the heating spot HS does not deviate from the opening region R when the heating spot HS moves. The width Wh corresponds to the diameter when the shape of the heating spot HS is adjusted to a circle, and corresponds to the short diameter of an ellipse or an ellipse when adjusted to an ellipse or an ellipse.

Further, the heating spot HS is moved and moved along a curve-parting line CL (circular portion CL ₁ ) (FIG. 1D). The width Wh of the heating spot is adjusted so that the irradiation range of the heating spot HS does not deviate from the opening region R also when moving along the curved segmentation line CL.
When the heating spot HS moves, a compressive stress is generated in the vicinity of the substrate surface in the opening region R immediately after the heating spot passes. On the other hand, the substrate surface that has passed for a while after passing through the heating spot HS is once heated and then naturally cooled to generate a tensile stress. Therefore, as a result of the stress gradient generated along the opening region R, as shown in the figure, the crack CR (straight line portion CR ₀ , circular portion) follows the heating spot HS at a position slightly spaced from the heating spot HS. CR ₁ ) is formed.

Further continues to move the heating spot HS, at the time of the move to the end point P ₁ of the division planned line CL, terminates irradiation heating spot HS (FIG. 1 (e)). In the present embodiment, since the cutting out a circular substrate is the object, and ends at the point you have finished irradiated the entire circumference of the circular portion CL ₁ of the division planned line CL. Note that if the shape to be cut out is not a closed curve such as a circle, one of the sides of the substrate G is the end point. Some time after finishing the irradiation of the heat spot HS, so cracks progresses to the end point P _1.

(Coating removal process)
Subsequently, the metal films MR and ML are removed (FIG. 1 (f)). For the removal of the metal films MR and ML, for example, an etching process such as a dry process using an HCL gas or a chlorine-containing gas as an etchant or a wet process such as dilute hydrochloric acid is used. Note that when another metal film or a transparent conductive film is used for the coating, an etchant suitable for removing each coating is used.

  By executing the above steps, the substrate G in which the crack CR is formed along the dividing line CL is formed.

Next, a crack forming apparatus used when the curvilinear crack forming method described with reference to FIGS. 1 and 2 is performed will be described.
FIG. 3 is a schematic configuration diagram showing an example of a crack forming apparatus used in the steps of FIGS. 1C, 1D, and 1E. FIG. 4 is a block diagram showing a configuration of a control system in the crack forming apparatus of FIG. FIG. 5 is a view for explaining an adjusting mechanism of the optical holder in the crack forming apparatus of FIG. FIG. 6 is a diagram showing teaching for the crack forming apparatus of FIG.

First, the overall configuration of the crack forming apparatus LS1 will be described with reference to FIG.
A slide table 2 that reciprocates in the front-rear direction (hereinafter referred to as the Y direction) in FIG. 3 is provided along a pair of guide rails 3 and 4 arranged in parallel on a horizontal base 1. A screw screw 5 is disposed between the guide rails 3 and 4 along the front-rear direction, and a stay 6 fixed to the slide table 2 is screwed to the screw screw 5. The slide table 2 is formed so as to reciprocate in the Y direction along the guide rails 3 and 4 by forward and reverse rotation (not shown).

  A horizontal pedestal 7 is arranged on the slide table 2 so as to reciprocate in the left-right direction in FIG. A screw screw 10a rotated by a motor 9 is threaded through a stay 10 fixed to the pedestal 7, and the pedestal 7 is moved along the guide rail 8 in the X direction when the screw screw 10a is rotated forward and backward. Move back and forth.

  A rotating table 12 that is rotated by a rotating mechanism 11 is provided on the pedestal 7, and the glass substrate G is attached to the rotating table 12 in a horizontal state. The rotation mechanism 11 is configured to rotate the rotary table 12 around a vertical axis, and is configured to be rotated at an arbitrary rotation angle with respect to a reference position. The substrate G is fixed to the rotary table 12 by, for example, a suction chuck.

  An optical holder 14 connected to the laser 13 is held on the frame 15 above the rotary table 12. As shown in FIG. 5, the optical holder 14 has a lens optical system for irradiating the substrate G with a laser beam transmitted from the laser 13 as a heating spot HS having a preset shape (circular, elliptical, etc.). 14a is provided. In the present embodiment, it is assumed that the circular heating spot HS is irradiated by the lens optical system 14a. Further, below the lens optical system 14a, the diameter Wh (corresponding to the width Wh in FIG. 2) of the heating spot HS is enlarged by changing the height h from the substrate surface and moving the focal position F up and down. An adjusting lens 14b for reducing is provided. When the heating spot HS is enlarged or reduced, the energy density irradiated on the substrate surface also changes. Therefore, when the heating spot HS is enlarged by the adjusting lens 14b, the output of the laser transmitter 13 is increased and the heating is performed. When the spot HS is reduced, the output of the laser transmitter 13 is adjusted to decrease.

  A pair of CCD cameras 20 (21) are fixed to the upper left of the crack forming apparatus LS1. As described in FIG. 1, the glass substrate G placed on the turntable 12 is provided with a pair of markers Gm and Gn (alignment marks) serving as processing reference points, and a pair of CCD cameras 20 (21). The image of these markers Gm and Gn is taken in a state where the rotary table 12 has returned to the origin position (the rotary table 12 in FIG. 3 has been moved to the left end). In FIG. 3, only the CCD camera 20 in front of the paper surface is shown, and the CCD camera 21 on the back side of the paper surface is not shown.

  By adjusting the slide table 2, the pedestal 7, and the rotary table 12 while monitoring the image of the substrate G projected by the CCD cameras 20, 21, the substrate G is aligned with the crack forming device LS1. By completing this positioning, each point of the substrate G is associated with the coordinate system set in the crack forming apparatus LS1.

  A cutter wheel 18 is attached above the rotary table 12 via a vertical movement adjusting mechanism 17. The cutter wheel 18 is made of sintered diamond or cemented carbide, and has a V-shaped ridge line portion with a vertex on the outer peripheral surface, and the pressure contact force to the glass substrate G is a vertical movement adjustment mechanism. 17 can be finely adjusted. When the initial crack TR is formed at the edge of the glass substrate G, the cutter wheel 18 is used so that the pedestal 7 is temporarily lowered from the standby position in the X direction and returned to the standby position.

  Next, the control system will be described with reference to FIG. In the crack forming apparatus LS1, a table driving unit 51 that drives a motor (such as the motor 9) for positioning the slide table 2 and the base 7, and a laser 13 and an adjustment lens 14b of the optical holder 14 are driven for laser beam irradiation. Each drive system of the laser drive unit 52, the cutter drive unit 54 that positions the cutter wheel 18 and adjusts the pressure contact force with respect to the glass substrate G, and the camera drive unit 55 that performs imaging by the CCD cameras 20 and 21 is a computer (CPU). It is controlled by the control unit 50 constituted by

  The control unit 50 is connected to an input unit 56 composed of an input device such as a keyboard and a mouse, and a display unit 57 composed of a display screen for performing various displays so that necessary messages are displayed on the display screen and necessary. Instructions and settings can be entered.

  Further, the control unit 50 includes a division line information input unit 58 that receives position data related to the division line CL by a teaching operation or a data input operation using a keyboard, and a memory such as a hard disk. A segmentation scheduled line information storage unit 59 for storing data input to the unit 58.

  Here, the input of the division line information to the crack forming apparatus LS1 by the teaching operation will be described with reference to FIG. The teaching described below is performed by designating the position of the substrate image displayed on the screen using a mouse or the like. In teaching, an input operation for shifting from the normal machining mode to the teaching mode is performed, and a program for storing the input data related to the position of the planned cutting line CL in the planned cutting line information input unit 58 is executed in the planned cutting line information storage unit 59. Is done.

  The substrate G placed on the turntable 12 is previously aligned. That is, by adjusting the slide table 2, the base 7, and the rotary table 12 while monitoring the images of the markers Gm and Gn of the substrate G displayed on the display unit 58 by the CCD cameras 20 and 21, cracks in the substrate G Positioning with respect to the forming apparatus LS1 is performed, and each point of the substrate G is associated with a coordinate system set in the crack forming apparatus LS1.

Next, as shown in FIG. 6, on the image projected on the display unit 57, the center line from the starting point P ₀ to the ending point P ₁ of the strip-shaped opening region R where cracks are to be formed (that is, the planned dividing line CL). A number of points along the line (indicated by X in the figure) are sequentially designated by the input unit 56 such as a mouse to perform teaching. The coordinates of each designated point are calculated, and a polygonal line (curve) connecting these points is stored in the planned division line information storage unit 59 as input data of the planned division line CL. At this time, a mathematical approximation process may be performed to perform a process for making the planned dividing line CL into a smooth curve.

In addition, instead of the input by the above teaching operation, coordinate data corresponding to the planned division line CL may be directly input, or a function formula may be input when the planned division line CL can be expressed by a function.
The information on the scheduled cutting line CL stored by the teaching operation is referred to when the crack forming device LS1 is returned to the processing mode to form a crack.

  Next, the operation of the crack forming apparatus LS1 will be described. First, teaching is performed with the crack forming device LS <b> 1 in the teaching mode, and the planned split line CL is stored in the planned split line information storage unit 59.

Subsequently, the normal processing mode is switched to start crack formation. When the process is started, the position data of the stored be cut line CL are read, the slide table 2 so as the cutter wheel 18 approaches the starting point P _0, the base 7 is moved. Further, when the cutter wheel is lowered, the substrate end approaches the cutter wheel, whereby an initial crack TR is formed at the substrate end.

Subsequently, the slide table 2 and the base 7 are moved so that the heating spot HS comes to a position immediately before the initial crack TR. Thereafter, the scanned heated spot HS along section scheduled line CL up to the end point P _1, thereby, cracks CR along the cutting-scheduled line CL is formed (FIG. 1 (c) ~ FIG 1 (e) reference).

(Embodiment 2)
Next, a second embodiment of the present invention will be described with reference to the drawings. FIG. 7 is a plan view of the substrate in each step of the curved crack forming method according to the second embodiment of the present invention. FIG. 8 is a cross-sectional view taken along line BB ′ in FIG. In this embodiment, in the first embodiment, immediately after the substrate is heated by the heating spot, the cooling by the cooling spot is performed. In addition, about the structure which is common in the structure demonstrated in FIG. 1, FIG. 2, the description is abbreviate | omitted by attaching | subjecting the same code | symbol. In the present embodiment, the case where a circular substrate is cut out will be described as an example.

(Board preparation process)
A rectangular glass substrate G is prepared as a processing substrate (FIG. 7A). This process is the same as that described in the first embodiment with reference to FIG.

(Film formation process)
Subsequently, metal films MR and ML are formed on the surface of the glass substrate G as a film for reflecting laser light (FIG. 7B). This process is also the same as that described in the first embodiment with reference to FIG.

(Crack formation process)
Subsequently, after forming an initial crack TR on the end face of the substrate G, the heating spot HS of the laser beam is moved from the initial crack TR along the line CL (initially a straight line portion CL ₀ ) to be divided, and further, the heating spot HS The cooling spot CS is moved so as to follow after the movement (FIG. 7C). Initial crack TR is formed by pressing a cutter wheel 18 described later crack forming apparatus LS2 (Fig. 9), the position of the starting point P ₀ of the cutting-scheduled line CL.

  The shape and size of the heating spot HS are adjusted by an optical holder 14 that incorporates an adjustment mechanism for adjusting the irradiation light from the laser 13 in a crack forming apparatus LS2 described later. As described with reference to FIG. 2 of the first embodiment, the width Wh that the heating spot HS irradiates the substrate G (including part of the metal films MR and ML) crosses the lateral width Wo (opening region R) of the opening region R. The width of the heating spot HS is adjusted so as not to deviate from the opening region R when the heating spot HS moves. The width Wh corresponds to the diameter when the shape of the heating spot HS is adjusted to a circle, and corresponds to the short diameter of an ellipse or an ellipse when adjusted to an ellipse or an ellipse.

    The cooling spot CS is formed by a cooling medium ejected from the cooling nozzle 16 in a crack forming apparatus LS2 (FIG. 9) described later. As shown in FIG. 8, the width Wc of the cooling spot CS sprayed onto the substrate G (including part of the metal films MR and ML) is wider than the lateral width Wo (width across the opening region R) of the opening region R. Thus, the irradiation range of the cooling spot CS is adjusted so as not to deviate from the opening region R when the cooling spot CS moves. The width Wc corresponds to the diameter when the shape of the cooling spot CS is circular. Normally, the cooling medium is sprayed from the cooling nozzles arranged obliquely as shown in FIG. 8, so that the cooling spot CS has an oval shape in which the circular shape is slightly distorted. In this case, the width Wc corresponds to the short diameter side. To do.

Further, the heating spot HS and the cooling spot CS are moved, and moved along a curved dividing line CL (circular portion CL ₁ ) (FIG. 7D). At this time, by rotating the substrate G in accordance with the curved shape, both the heating spot HS and the cooling spot CS move so as not to deviate from the division line CL of the substrate G. In the crack forming apparatus LS2 (FIG. 9), which will be described later, the substrate G is moved in such a manner that a rotational movement by the rotary table 12 is added to a translational movement (XY direction movement) by the slide table 2 and the base 7.

When the heating spot HS moves, a compressive stress is generated in the vicinity of the substrate surface in the opening region R immediately after the heating spot passes. Subsequently, when the cooling spot CS passes immediately after the heating spot HS passes, the vicinity of the substrate surface is forcibly quenched immediately after being heated once, and a strong tensile stress is generated. At this time, in the vicinity where the cooling spot has passed, compressive stress remains inside the substrate, and tensile stress is generated on the surface of the substrate thereon by forced cooling, resulting in a strong stress gradient in the depth (up and down) direction. As a result, as shown in FIG. 7D, a crack CR (straight line portion CR ₀ , circular portion CR ₁ ) is formed along the opening region R immediately after the cooling spot CS.

Further continues to move the heating spot HS and cooling spot CS, when the cooling spot CS is moved to the end point P ₁ of the division planned line CL, terminate the irradiation and the refrigerant injection cooling spot of the heating spot HS (FIG. 7 (e) ).

(Coating removal process)
Subsequently, the metal films MR and ML are removed (FIG. 7F). This process is the same as that described in the first embodiment with reference to FIG.
As a result, the substrate G in which the crack CR is formed along the division line CL is formed.

Next, a crack forming apparatus used when the curvilinear crack forming method described with reference to FIGS. 7 and 8 is performed will be described.
FIG. 9 is a schematic configuration diagram showing an example of a crack forming apparatus used in the steps of FIGS. 7C, 7D, and 7E. FIG. 10 is a block diagram showing a configuration of a control system in the crack forming apparatus of FIG. 3 and FIG. 4 are denoted by the same reference numerals, and a part of the description is omitted.

  As shown in FIG. 9, the crack forming device LS <b> 2 includes the configuration described in the crack forming device LS <b> 1 as a basic structure, and the frame 15 is provided with a cooling nozzle 16 adjacent to the optical holder 14. From the cooling nozzle 16, a cooling medium such as cooling water, He gas, and carbon dioxide gas is jetted onto the glass substrate G. The cooling medium is sprayed to a position close to the heating spot HS irradiated on the glass substrate G to form a substantially circular cooling spot CS on the surface of the glass substrate G. The size of the cooling spot CS is adjusted by the distance between the tip of the cooling nozzle 16 and the substrate surface. Further, in order to specify the direction of the cooling spot CS with respect to the heating spot HS, the position of the cooling spot CS is set to be in the −X axis direction with respect to the heating spot HS. Thus, if the substrate G is moved in a specific direction (X-axis direction), the cooling spot CS always passes through the heating portion immediately after the heating spot HS passes.

Further, as shown in FIG. 10, the crack forming apparatus LS2 also includes the components described in the crack forming apparatus LS1 for the control system, and is further connected to the cooling nozzle 16 to control an on-off valve (not shown). ) Is provided.
The table drive unit 51 drives the motor (not shown) of the rotation mechanism 11 that positions the rotary table 12 as well as the motors of the slide table 2 and the pedestal 7 (such as the motor 9). Thereby, in addition to movement control in the XY directions, control of rotational movement by the rotary table 12 can be performed.

  Next, the operation of the crack forming apparatus LS2 will be described. Similarly to the crack forming device LS1, teaching is performed with the crack forming device LS2 in the teaching mode, and the planned dividing line CL is stored in the planned dividing line information storage unit 59.

Subsequently, the normal processing mode is switched to start crack formation. When the process is started, data of the stored be cut line CL are read, the slide table 2 so as the cutter wheel 18 approaches the starting point P _0, the pedestal 7 is moved. Further, when the cutter wheel is lowered, the substrate end approaches the cutter wheel, whereby an initial crack TR is formed at the substrate end.

Subsequently, the slide table 2, the pedestal 7, and the rotary table 12 are driven so that the heating spot HS and the cooling spot CS move along the scheduled cutting line CL, starting from the position of the initial crack TR (starting point P ₀ ). To do.
Specifically, the tangent direction at each point is calculated based on the stored data of the scheduled division line CL at each point (initially the starting point P ₀ ) of the planned division line CL. Since the heating spot HS and the cooling spot CS are adjusted so as to be aligned in the X-axis direction, when the heating spot HS is moved along the division line CL, the tangential direction of the division line CL at each point The rotary table 12 is rotated so that is in the X-axis direction, and the irradiation position is adjusted by the slide table 2 and the base 7. Thereby, the heating spot HS and the cooling spot CS are surely passed through the scheduled dividing line CL.

Thereafter, the scanned heated spot HS and cooling spot along section scheduled line CL up to the end point P _1, thereby, cracks CR along the cutting-scheduled line CL is formed (FIG. 7 (c) ~ 7 (See (e)).

(Embodiment 3)
Embodiment 1 and Embodiment 2 demonstrated the case where a disk substrate was cut out from the square glass substrate G. FIG. Here, a case where a curved substrate is divided into a mounting substrate on which a wiring electrode film (functional film) is formed will be described.

  FIG. 11 is a plan view showing an example of a glass mounting board. The mounting substrate G0 has a substrate shape in which the corner portions of the four corners are rounded and curved, and an electrode portion E made of an ITO film (transparent conductive film) is formed in the vicinity of the center of the substrate in a finished product state. Yes.

FIG. 12 is a plan view of the substrate in each step when the mounting substrate G0 is created from the processing glass substrate.
First, as shown in FIG. 12A, a rectangular glass substrate G1 is prepared.
Subsequently, an electrode portion E is patterned on the glass substrate G1 by a sputtering method using a patterning mask. In this case using a patterning mask for forming the electrode portions E, at the same time, to coat E _L, the E _R patterning. The coatings E _L and E _R are formed so as to sandwich the band-shaped opening region R in which the division line CL is the center line. As a result, a substrate G2 patterned as shown in FIG. 12B is formed.

  Subsequently, the heating spot HS (or the heating spot HS and the cooling spot CS) is moved along the scheduled cutting line CL by using any one of the crack forming apparatuses LS1 and LS2 described in the first and second embodiments. Thereby, a crack is formed along the division | segmentation planned line CL, and the board | substrate G3 shown in FIG.12 (c) is formed by performing a break process.

Subsequently, a resist film is applied on the electrode portion E, the coating _EL is exposed, and etching is performed with an etchant capable of removing the ITO film. As a result, as shown in FIG. 12D, a finished substrate G0 is formed.
According to this embodiment, when forming the electrode portions E, it is possible to form coating E _L, the E _R simultaneously without adding an extra step to produce a film for cutting the curved shape be able to.

(Embodiment 4)
In the embodiments so far, a metal film or a transparent conductive film has been used as the film. However, any film can be used as long as it can block laser light and prevent the heat generated by laser irradiation from being transmitted to the substrate. A film other than a metal film and a transparent conductive film can also be used as a film for forming the opening region. For example, if the substrate processing step includes a step of applying a resist film, a protective film, etc., and these films are materials that can be used as a film for forming the opening region, the coating step is for forming the opening region. These films are formed simultaneously. Thereby, a laser beam can be irradiated with a material such as a resist film or a protective film as a coating, and a curved crack can be formed.

(Embodiment 5)
In the first to fourth embodiments, the film for forming the opening region is formed on the processing substrate by the film forming process. In this embodiment, it coat | covers by replacing with a film formation process and performing the process of mounting a sheet | seat member on a board | substrate.

  FIG. 13 is a plan view showing an example of a sheet member placed on the square glass substrate G1. The sheet member SH is formed of a thin stainless steel metal mask, and the length Sa and the width Sb are made to coincide with the substrate G1, thereby facilitating alignment with the substrate.

The belt-like sheet member SH is the consists of a left seat member SH _R and right seat member SH _L and a plurality of connecting members SH _B, and the left seat member SH _L and the right seat member SH _R is the center line be cut line CL Are arranged so as to sandwich the opening region R. The connecting member SH _B integrates the sheet member SH. This eliminates the need of position adjustment between the left seat member SH _L and the right seat member SH _R. Incidentally, when the heat spots or cool spots on the coupling member SH _B has passed, so as not to progress of the crack is prevented immediately below, a longitudinal width W _L to be sufficiently small. Specifically have set longitudinal width _{W L} in the range of 0.1 mm to 2 mm.

  The substrate G1 and the sheet member SH may be fixed using a fixing jig at a position that does not hinder laser irradiation or refrigerant injection. Further, an adhesive layer may be provided on the sheet member SH to be fixed to the substrate G1. Further, the metal mask may be taped and attached to the substrate G1.

  According to this embodiment, it is possible to form a coating along a planned dividing line by simply placing a sheet member on a substrate on which a film is not formed.

(Embodiment 6)
Next, a further improvement in the case of performing the punching process by forming a closed-curved crack on the substrate will be described. When the scribe line including the curved portion is formed in a closed curve shape, it is necessary to take out a part of the substrate that is a member inside the closed curve from the original substrate. As an actual application example, when taking out the inner member (cut-out part) of the original substrate and using the outer substrate (case 1), the inner member is taken out and used, but the outer original substrate is processed into end materials. (Case 2), as a case of processing and using as a substrate for a storage medium such as HD, the outermost original substrate is treated as a waste material, and the central portion of the inner member is cut out to form a donut-shaped member Is used as a substrate (case 3).

In such a process called profile cutting, after scribing is performed, consideration should be given to provide a draft so that the predetermined part of the substrate can be taken out easily. is required.
The description so far has been based on the assumption that cracks formed by irradiating a laser beam from above the substrate are formed in the vertical direction from the substrate surface. However, in the case of profile cutting especially when the thickness of the substrate is increased, the processing for providing the draft described above is effective instead of forming a vertical crack.

Of the processing of brittle materials, a CO ₂ laser is generally used for glass, but most of the laser beam energy is absorbed in the vicinity of the substrate surface (surface absorption), and then heat conduction. As a result of heat being transferred three-dimensionally into the substrate, cracks formed after cooling also extend vertically from the substrate surface.

Therefore, when there is a need to provide a draft, not only surface absorption but also a laser transmitter that emits light in the wavelength band where laser light is absorbed deeply into the substrate (internal absorption) is used. Cracks formed after laser scribing with the cooling operation are formed to extend in a direction inclined by a necessary angle from the vertical direction of the substrate surface. The light in the wavelength band in which the laser beam is absorbed deep inside the substrate does not absorb almost all of the irradiation energy just near the substrate surface as in the case of a CO ₂ laser. It refers to laser light in a wavelength band that creates a situation where irradiation energy reaches the inside and heat is not transferred by heat conduction but directly converted into heat energy deep inside the substrate (for example, Er: YAG laser, Ho: YAG laser). Regarding processing using such laser light, there is PCT / JP03 / 02961 (WO03 / 076151) as a related prior application.

  With the laser beam from the laser transmitter that emits laser light in such a wavelength band tilted by the required angle from the vertical direction of the substrate surface, the substrate to be processed and the laser beam are relative to each other at the required processing speed. Move to form cracks. In order to increase the crack depth and enhance the draft effect, the laser beam of the same wavelength band is also used when the second laser irradiation is performed after the heating and cooling by the first laser irradiation. Similarly, it can be deepened by irradiating from an oblique direction.

  INDUSTRIAL APPLICABILITY The present invention can be used when a curved crack is formed on a brittle material substrate such as a glass substrate and the substrate is divided.

The top view of the board | substrate in each process of the curvilinear crack formation method which is one Embodiment of this invention. A-A 'sectional view in Drawing 1 (b), Drawing 1 (c), and Drawing 1 (d). The schematic block diagram which shows an example of the crack formation apparatus used at the process of FIG.1 (c), FIG.1 (d), and FIG.1 (e). The block diagram which shows the structure of the control system in the crack formation apparatus of FIG. The figure explaining the adjustment mechanism of the optical holder in the crack formation apparatus of FIG. The figure which shows teaching with respect to the crack formation apparatus of FIG. The top view of the board | substrate in each process of the curvilinear crack formation method which is other one Embodiment of this invention. B-B 'sectional drawing in FIG.7 (c). FIG. 8 is a schematic configuration diagram showing an example of a crack forming apparatus used in the steps of FIGS. 7C, 7D, and 7E. The block diagram which shows the structure of the control system in the crack formation apparatus of FIG. The top view which shows an example of the board | substrate for mounting. Process drawing explaining each process when producing a mounting substrate. The top view which shows an example of the sheet | seat member mounted in a square board | substrate. The figure which shows the typical example of the position shift which arises between the curve scheduled division line and the crack actually formed. The figure which shows an example of the locus | trajectory of a heating spot and the locus | trajectory of a cooling spot when a heating spot is moved along the division | segmentation plan line of a curve shape. It shows a peak position HS _T of the heating in the heating spot of the heating spot and the heat spot in the movement stopped.

Explanation of symbols

2 Slide table 12 Rotating table 13 Laser 14 Optical holder 16 Cooling nozzle 18 Cutter wheel 50 Control unit 51 Table drive unit 52 Laser drive unit 53 Nozzle drive unit 54 Cutter drive unit 55 Camera drive unit 56 Input unit 57 Display unit 58 Line to be divided information input unit 59 be cut line information storage unit 20, 21 camera G, G0~G4 a glass substrate CL be cut line M _{L, M R} film opened R region TR initial crack CR cracks E electrode unit E _{L, E R} coating SH sheet Member SH _L , SH _R sheet member HS Heating spot CS Cooling spot

Claims (14)

The substrate is formed by setting a curve-shaped segmentation scheduled line for a substrate made of a brittle material, and relatively heating a heating spot formed by a laser beam along the segmentation planned line and heating it at a temperature below the softening point. A method for forming a curved crack in a brittle material substrate that forms a crack in the substrate,
A center line has a band-shaped opening region that coincides with the planned dividing line, and shields the heating spot from passing over the substrate surface other than the opening region when the heating spot is relatively moved along the planned dividing line. Coating means to be provided on the substrate surface,
A method for forming a curved crack in a brittle material substrate, wherein a heating spot wider than a lateral width of the opening region is formed, and the heating spot is relatively moved along a division line while covering a part of the opening region. A cutting line with a curved shape is set for a substrate made of a brittle material, a heating spot formed by a laser beam is relatively moved along the cutting line, and heated at a temperature below the softening point. A method for forming a curved crack in a brittle material substrate in which a crack is formed in the substrate by relatively moving a sprayed cooling spot along the division planned line,
A center line has a band-shaped opening region that coincides with the planned dividing line, and when the heating spot and the cooling spot are relatively moved along the planned dividing line, the heating spot and cooling are performed on the substrate surface other than the opening region. A coating means for shielding the spot from passing is provided on the substrate surface,
A heating spot that is wider than the lateral width of the opening region is formed, and the heating spot is moved relative to the parting line while covering a part of the opening region.
A brittle material characterized in that it forms a cooling spot wider than the lateral width of the opening region, and the cooling spot moves relative to the parting line immediately after the heating spot passes while covering a part of the opening region. A method for forming a curved crack in a substrate.   The curved crack forming method according to claim 1, wherein the covering means is a film formed on the surface of the substrate.   The film is a metal film or a transparent conductive film that reflects a laser beam of a heating spot that passes over the film and diffuses cold heat generated by a refrigerant by heat conduction when a cooling spot passes over the film. 4. The method for forming a curved crack according to 3.   The brittle material substrate is formed with a functional film region made of a metal film or a transparent conductive film for generating a function in a part of the substrate, and the coating is the same as the functional film region when the functional film region is formed. The method for forming a curved crack according to claim 4, wherein the method is formed simultaneously using a material.   6. The curved crack forming method according to claim 5, wherein after the crack is formed, the coating film is removed leaving the functional film region.   The curved crack forming method according to claim 1, wherein the covering means is a sheet member that is placed on or fixed to the surface of the substrate.   The sheet member is formed of a metal mask that reflects a laser beam of the heating spot that passes over the sheet member, and diffuses cold heat generated by the refrigerant by heat conduction when the cooling spot passes over the sheet member. The method for forming a curved crack as described.   The sheet member includes a left sheet member disposed on the left side of the opening region, a right sheet member disposed on the right side of the opening region, and a plurality of connections that connect the left sheet member and the right sheet member on the opening region. The left sheet member and the right sheet member are connected to each other at a vertical width that does not hinder the formation of cracks immediately below each connecting portion when the heating spot and the cooling spot pass through each connecting portion. The curved crack formation method of Claim 7 or Claim 8.   The method for forming a curved crack according to claim 9, wherein a vertical width of each of the connecting portions is 0.1 mm to 2 mm.   The method for forming a curved crack according to any one of claims 1 to 9, wherein a width of the opening region is 0.1 mm to 2 mm.   A brittle material substrate, characterized in that a cut line having a curved shape is set, and a coating is formed on the surface of the substrate so as to form a band-shaped opening region with the cut line as a center line.   The brittle material substrate according to claim 12, wherein a lateral width of the opening region is 0.1 mm to 2 mm.   A laser beam having a wavelength that can be absorbed from the substrate surface to the inside of the substrate is used, and a draft angle is formed by irradiating the laser beam obliquely with respect to the substrate along a planned dividing line forming a closed curve. The curvilinear crack forming method according to any one of claims 1 to 11.

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