JP2010024068A - Method for dividing substrate and method for manufacturing display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for dividing a substrate capable of securing easiness and cross-sectional accuracy in dividing a substrate and deterring a deterioration of working efficiency and a method for manufacturing a display using the method for dividing a substrate. <P>SOLUTION: The method is for dividing a substrate by forming a reformed region r in the inside of the substrate 4 along a division scheduled line of the substrate 4 by irradiating the substrate 4 with laser light and dividing the substrate 4 by applying external force to the substrate 4 in which the reformed region r is formed. The method has a process to form a first reformed region r1 at the position where a crack is generated on the surface of the substrate 4 and a process for forming a second reformed region r2 at the position where the crack generated on the surface of the substrate 4 is guided to be vertically extended toward the backside of the substrate 4 when external force is applied to the substrate 4. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a substrate dividing method for irradiating a substrate with laser light to form a modified region along the planned dividing line of the substrate, and a method for manufacturing a display device using the substrate dividing method.

Conventionally, as this type of technology, for example, there is a method of irradiating a focused laser beam onto a substrate to form modified regions at a plurality of positions along the depth direction of the substrate within the substrate (for example, Patent Documents 1 and 2).
In the above conventional technique, by forming the modified regions at a plurality of positions along the depth direction of the substrate, the substrate can be easily divided and the cross-sectional accuracy of the divided substrate can be improved. .

Note that when the substrate is divided by such a method, the greater the number of modified regions in the depth direction of the substrate, the more easily the substrate can be divided and the cross-sectional accuracy can be improved.
JP 2002-192367 A JP 2002-205180 A

However, in the conventional technique, as the number of modified regions formed in the depth direction of the substrate increases, the time for irradiating the laser beam along the planned dividing line increases, and the work efficiency when dividing the substrate is increased. May fall.
The present invention has been made in view of the above prior art, and is a substrate dividing method capable of suppressing a decrease in work efficiency while ensuring ease and sectional accuracy when dividing a substrate, and the substrate. It is an object of the present invention to provide a method for manufacturing a display device using a dividing method.

  In order to achieve the above object, a substrate dividing method according to a first aspect of the invention irradiates a substrate with laser light, forms a modified region in the substrate along a planned dividing line of the substrate, and modifies the substrate. A substrate dividing method for dividing a substrate by applying an external force to the substrate on which the quality region is formed, wherein the first modified region is formed at a depth position where a crack is generated on the surface of the substrate. The second modified region is formed at a depth position that induces a crack generated on the surface of the substrate to extend vertically toward the back surface side of the substrate when an external force is applied to the substrate region forming step. And a second modified region forming step to be formed.

In the substrate dividing method according to the first invention, the first modified region is formed at a depth position where cracks are generated on the surface of the substrate, thereby ensuring the ease of cracking of the substrate when an external force is applied to the substrate. can do. Further, by forming a second modified region at a depth position that induces a crack generated on the surface of the substrate to extend vertically toward the back side of the substrate when an external force is applied to the substrate, The cross-sectional accuracy of the divided substrate can be ensured.
In addition, by forming the modified regions at the depth position where cracks are generated on the surface of the substrate and the depth positions where the cracks generated on the surface of the substrate are guided to extend vertically toward the back side of the substrate, respectively. Thus, it is possible to appropriately arrange the modified regions in the depth direction of the substrate, and it is possible to suppress a decrease in work efficiency when the substrate is divided.
Here, the division line is a line that is set to the substrate before division and is a target for dividing the substrate (hereinafter the same). The planned dividing line may be a virtual line or a line formed by a groove or the like.

The substrate dividing method according to the second invention is the substrate dividing method according to the first invention, wherein in the first modified region forming step, the first modified region is formed on the surface portion of the substrate, In the second modified region forming step, the second modified region is formed in the central portion in the depth direction of the substrate.
In the substrate dividing method according to the second invention, it is possible to efficiently generate a crack on the surface of the substrate by forming the first modified region on the surface portion of the substrate. Further, by forming the second modified region at the center of the substrate in the depth direction, the cracks generated on the surface of the substrate by the first modified region are efficiently perpendicularly directed toward the back surface side of the substrate. It can be guided to stretch.
Here, the surface portion of the substrate on which the first modified region is formed is, for example, a distance between the surface of the first modified region on the surface side of the substrate and the surface of the substrate of 40 to 50 μm. Says the position.

Further, the substrate dividing method according to the third invention is the substrate dividing method according to the first invention, wherein in the first modified region forming step, the first modified region is formed on the surface portion of the substrate, In the second modified region forming step, the second modified region is defined as the dimension in the depth direction of the unmodified region between the end portion on the back surface side of the first modified region and the back surface of the substrate. It forms in the position which equally divides (n is an integer greater than or equal to 2).
In the substrate dividing method according to the third aspect of the present invention, it is possible to efficiently generate cracks on the surface of the substrate by forming the first modified region on the surface portion of the substrate. Further, the second modified region is formed at a position where the dimension in the depth direction of the unmodified region between the end portion on the back surface side of the first modified region and the back surface of the substrate is equally divided by n. In other words, in the unmodified region between the back surface side end portion of the first modified region and the back surface of the substrate, the n-1 second modified region is formed so as to be substantially evenly arranged. The This makes it possible to efficiently induce a crack generated on the surface of the substrate by the first modified region so as to extend vertically toward the back surface side of the substrate.

For example, when two modified regions are formed along the depth direction of the substrate, the first modified region is formed on the front surface portion of the substrate, and the end portion on the back surface side of the first modified region A second modified region is formed at a position that bisects the dimension in the depth direction of the unmodified region between the substrate and the back surface of the substrate.
Similarly, when three modified regions are formed along the depth direction of the substrate, first, the first modified region is formed on the surface portion of the substrate. Further, the first second modification is provided at a position where the dimension in the depth direction of the unmodified region between the end on the back surface side of the first modified region and the back surface of the substrate is divided into three equal parts. A quality region, a second second modified region is formed.

The substrate dividing method according to a fourth aspect of the present invention is the substrate dividing method according to the third aspect of the present invention, wherein in each of the second modified region forming step, each unmodified portion divided into n by the second modified region. The value of n is set so that the dimension in the depth direction of the mass region is 500 μm or less, and the second modified region is formed.
Here, when the dimension in the depth direction of the unmodified region existing on the substrate increases, when an external force is applied to divide the substrate, the portion of the unmodified region of the divided section is scraped. In particular, when the dimension in the depth direction of the unmodified region existing on the substrate exceeds 500 μm, the shaving generated in the portion of the unmodified region of the divided cross section becomes significant. Note that shaving refers to irregularities such as burrs and oblique cracks that occur on a divided section of a divided substrate.

Therefore, in the substrate dividing method according to the fourth aspect of the present invention, the second modified region is formed so that the dimension in the depth direction of each unmodified region existing on the substrate is 500 μm or less, thereby dividing the sectional surface. It is possible to suppress the occurrence of shaving.
Here, the unmodified region refers to a region of the substrate that has not been modified by laser light irradiation.

The substrate dividing method according to the fifth invention is the substrate dividing method according to any one of the first to fourth inventions, wherein the dimension in the depth direction of the first modified region is changed to the second modified value. It is characterized in that it is formed larger than the dimension of the quality region in the depth direction.
In the substrate dividing method according to the fifth aspect of the present invention, the first modified region is formed to have a larger dimension in the depth direction than the second modified region in the depth direction. The dimension in the depth direction of the unmodified region existing between the end portion on the back surface side of the quality region and the back surface of the substrate is reduced.
Therefore, according to the substrate dividing method according to the fifth aspect of the present invention, it is possible to suppress the occurrence of shaving in the divided cross section by reducing the dimension in the depth direction of the unmodified region existing in the substrate. Become.

Here, as a method of forming the first modified region with a large dimension in the depth direction, a method of lengthening the condensing region of the laser light by increasing the aberration of the laser light can be considered. Further, as a method of forming the first modified region with a large dimension in the depth direction, a method of increasing the intensity of the laser beam may be employed.
Furthermore, the display device manufacturing method according to the sixth invention is characterized in that the display device substrate is divided from the substrate by the substrate dividing method according to any one of the first to fifth inventions.
According to the method for manufacturing a display device according to the sixth invention, the cross-sectional accuracy is ensured by dividing the display device substrate from the substrate by the substrate dividing method according to any one of the first to fifth inventions. It is possible to manufacture a display device using a substrate.

Next, embodiments of a substrate dividing method and a display device manufacturing method according to the present invention will be described with reference to the drawings.
In the present embodiment, an example in which the substrate dividing method and the display device manufacturing method according to the present invention are applied to a manufacturing process of a liquid crystal display panel constituting the liquid crystal display device will be described.
In particular, in the present embodiment, a method of cutting (dividing) a TFT substrate used in a liquid crystal display panel from a wafer-like substrate to be divided in a manufacturing process of a liquid crystal display panel constituting the liquid crystal display device will be described. Note that the liquid crystal display panel includes a TFT substrate having TFTs, a counter substrate having counter electrodes, and liquid crystal filled in a gap between the substrates.

(Configuration of substrate to be divided)
FIG. 1 is a plan view showing a division target substrate in a state before division.
The division target substrate 4 shown in FIG. 1 is formed by bonding a plurality of quartz substrates. In addition, the division target substrate 4 is provided with an insulating layer (not shown), a pixel electrode (not shown), and the like constituting a functional unit as a TFT film.

(About laser scribing method)
Next, a laser scribing method for dividing the division target substrate 4 with laser light (beam) will be described.
FIG. 2 is a conceptual diagram of the laser scribing method. As described above, the TFT substrate is formed by bonding a plurality of substrates, but in FIG. 2, the division target substrate 4 is shown as a single quartz substrate.
As shown in FIG. 2, when a laser beam focused on the inside of the division target substrate 4 is irradiated by a laser beam irradiation apparatus 10 to be described later, a modified region is formed in the laser beam focusing region 5 on the division target substrate 4. Is done.

Then, a modified region is formed in the division target substrate 4 along a planned division line set for the division target substrate 4. Furthermore, when an external force is applied to the division target substrate 4 on which the modified region is formed, the division target substrate 4 is divided along the modified region. Thereby, the TFT substrate used for the liquid crystal display panel is formed from the division target substrate 4.
Here, the planned division line refers to a line set as the division target board 4 and serving as a target for dividing the division target board 4. The planned dividing line may be a virtual line or a line made of a groove or the like formed on the surface of the division target substrate 4.

(Configuration of laser beam irradiation device)
Next, the laser beam irradiation apparatus 10 used for implementation of the laser scribing method will be described.
FIG. 3 is a schematic configuration diagram showing a laser beam irradiation apparatus.
A laser beam irradiation apparatus 10 shown in FIG. 3 includes a laser light source 11 that emits laser light, a dichroic mirror 12 that reflects the emitted laser light, a condenser lens 13 that condenses the reflected laser light, and an object to be divided. And a stage 17 on which the substrate 4 is placed.
As the laser light source 11, for example, a so-called femtosecond laser that emits a laser beam having titanium sapphire as a solid light source with a pulse width of femtosecond is used. In this case, the pulse laser beam has wavelength dispersion characteristics, the center wavelength is 800 nm, the pulse width is about 300 fs (femtosecond), the pulse period is 5 kHz, and the output is about 2.5 W. As the laser light source 11, a picosecond pulse laser (center wavelength: 1064 nm, pulse width: 10 ps, average output: 10 W), YAG laser (wavelength: 355 nm, pulse width: 35 ns, average output: 10 W) or the like is used. Is also possible.

As the condenser lens 13, for example, an objective lens having a magnification of 100 times, a numerical aperture (NA) of 0.8, and a WD (Working Distance) of 3 mm is used. In addition, the condensing lens 13 should just have a numerical aperture of 0.1 or more, and is not limited above. The condenser lens 13 is supported by a stand arm 14 a extending from the Z-axis slide mechanism 14.
Further, the laser beam irradiation apparatus 10 includes an X-axis slide unit 20 that moves the stage 17 in the X-axis direction (left-right direction in FIG. 3) with respect to the condenser lens 13, and the stage 17 with respect to the condenser lens 13. And a Y-axis slide portion 21 that is moved in the axial direction (the depth direction in FIG. 3). The X-axis slide unit 20 and the Y-axis slide unit 21 adjust the horizontal position of the stage 17 to adjust the horizontal position of the laser beam irradiated to the division target substrate 4 placed on the stage 17. Can be adjusted.

The laser beam irradiation apparatus 10 also includes a Z-axis slide mechanism 14 that moves the condenser lens 13 in the Z-axis direction (vertical direction in FIG. 3) with respect to the stage 17. The Z-axis slide mechanism 14 adjusts the vertical position of the condensing lens 13 to thereby adjust the vertical position of the condensing region of the laser light irradiated onto the division target substrate 4 placed on the stage 17. Can be adjusted. The Z-axis slide mechanism 14 incorporates a position sensor (not shown) that can detect the movement distance.
Further, the laser beam irradiation apparatus 10 includes a quartz glass plate 16 that corrects aberration of laser light. The quartz glass plate 16 is disposed between the condenser lens 13 and the division target substrate 4 so as to be orthogonal to the optical axis of the laser light. The quartz glass plate 16 is attached to the tip of a rotating arm 15 a extending from a motor 15 that moves with the Z-axis slide mechanism 14. Note that the laser beam irradiation apparatus 10 may include a condensing lens 13 having an aberration correction function instead of the quartz glass plate 16.

Further, the laser beam irradiation apparatus 10 includes an imaging device 22 that images the division target substrate 4 placed on the stage 17. The imaging device 22 is disposed on the opposite side of the condenser lens 13 with the dichroic mirror 12 interposed therebetween. The imaging device 22 includes a coaxial incident light source and a CCD (solid-state imaging device), and is configured such that visible light emitted from the coaxial incident light source passes through the condenser lens 13 and is focused.
In addition, the laser beam irradiation apparatus 10 includes a main computer 30 that controls the above-described components. The main computer 30 includes a CPU, various memories, and an image processing unit 34 that processes image information captured by the imaging device 22.

  Connected to the main computer 30 are an input unit 35 for inputting data of various processing conditions used in laser processing and a display unit 36 for displaying various information at the time of laser processing. The main computer 30 also includes a laser controller 31 that controls the output, pulse width, and pulse period of the laser light source 11 and a Z-axis slide mechanism 14 to control the position of the condenser lens 13 in the Z-axis direction. Control units 32 are connected to each other. Further, a stage control unit 33 that drives a servo motor (not shown) that moves the X-axis slide unit 20 and the Y-axis slide unit 21 along the rails 18 and 19, respectively, is connected to the main computer 30.

The lens control unit 32 can detect the output of a position sensor built in the Z-axis slide mechanism 14 and control the position of the condenser lens 13 in the Z-axis direction. Accordingly, the focusing lens 13 is moved in the Z-axis direction so that the focal point of the visible light emitted from the coaxial incident light source of the imaging device 22 coincides with the surface of the division target substrate 4, so that the depth of the division target substrate 4 is increased. It is possible to measure the dimension in the vertical direction (vertical direction in FIGS. 3 and 5). In addition, the lens control unit 32 drives the Z-axis slide mechanism 14 and also drives the motor 15 to rotate the rotating arm 15a around the Z-axis, so that the quartz glass is formed on the front surface of the opening 13a of the condenser lens 13. A plate 16 can be inserted.
Further, the laser beam irradiation device 10 includes a reflection type distance measuring device 9 using laser light. The reflection type distance measuring device 9 is, for example, a dimension in the depth direction of each quartz substrate by measuring the distance to the front and back surfaces of each quartz substrate even in the case of the division target substrate 4 in which a plurality of quartz substrates are stacked. Can be detected.

(Operation of laser beam irradiation device)
The laser beam irradiation apparatus 10 irradiates the division target substrate 4 placed on the stage 17 with laser light, and forms a modified region in the condensing region of the laser light on the division target substrate 4.
The laser beam irradiation apparatus 10 can form a modified region along the planned division line set on the division target substrate 4.
Further, the laser beam irradiation apparatus 10 can form the modified regions at a plurality of positions (depth positions) along the depth direction (vertical direction in FIG. 5) of the division target substrate 4.
Further, the laser beam irradiation apparatus 10 uses the quartz glass plate 16 as the aberration correction means to lengthen the condensing region of the laser light, that is, to lengthen the region having a high energy density, thereby increasing the depth of the modified region. It can be formed long in the direction.

(About the substrate dividing method according to the present invention)
Next, the substrate dividing method according to the present invention will be described.
FIG. 4 is a flowchart showing a substrate dividing method according to the present invention.
In the substrate dividing method according to the present invention, as shown in FIG. 4, first, when the division target substrate 4 is divided by the laser beam irradiation apparatus 10, a preliminary survey is performed on the settings of the laser beam irradiation apparatus 10 (steps). S100).
In the preliminary investigation in step S100, the position of the condenser lens 13 of the laser beam irradiation apparatus 10 in the Z-axis direction, the position in the depth direction of the modified region formed on the division target substrate 4 placed on the stage 17, and The relationship with the dimension in the depth direction of the modified region is determined.

Next, the arrangement of the modified regions to be formed on the division target substrate 4 is determined by the laser beam irradiation apparatus 10 (step S101). Here, the arrangement of the modified region refers to the arrangement of the modified region in the depth direction of the division target substrate 4.
In the substrate dividing method according to the present invention, the modified regions are arranged at a plurality of positions along the depth direction of the division target substrate 4.
In this case, when the modified region is formed on the division target substrate 4 in step S102 described later, the first modified region is located at a position where a crack (hereinafter referred to as a surface crack) is generated on the surface of the division target substrate 4. Deploy.

Further, when an external force is applied to the division target substrate 4 in step S103 to be described later, a surface crack generated in the division target substrate 4 is guided to extend vertically toward the back side of the division target substrate 4. A second modified region is placed.
And according to the arrangement | positioning determined by step S101, the modification area | region is formed in the division | segmentation target board | substrate 4 with the laser beam irradiation apparatus 10 (step S102).
In this case, in step S102, the position in the Z-axis direction of the condenser lens 13 of the laser beam irradiation apparatus 10 is adjusted based on the result of the preliminary investigation in step S100.
In addition, when forming a modification area | region in the several position along the depth direction of the division | segmentation target board | substrate 4, it is preferable to form in order from the modification | reformation area | region located in the back surface side of the division | segmentation target board | substrate 4, You may form sequentially from the modification | reformation area | region located in the surface side of the board | substrate 4. FIG.

Further, the division target substrate 4 is divided by applying an external force to the division target substrate 4 in which the modified regions are formed at a plurality of positions along the depth direction (step S103). Thereby, the division | segmentation object board | substrate 4 is divided | segmented and the TFT substrate used for a liquid crystal display panel is formed.
In this case, the surface crack generated in the division target substrate 4 due to the first modified region ensures the fragility of the division target substrate 4 when an external force is applied to the division target substrate 4 in step S103.
In addition, when an external force is applied to the division target substrate 4 in step S <b> 103, the second modified region extends a surface crack generated in the division target substrate 4 vertically toward the back side of the division target substrate 4. By guiding, the cross-sectional accuracy of the divided TFT substrate is ensured.

Further, a modified region is formed at a position where a surface crack is generated in the division target substrate 4 and a position where the surface crack generated in the division target substrate 4 is guided to extend vertically toward the back side of the division target substrate 4. By doing so, it is possible to appropriately arrange the modified regions in the depth direction of the division target substrate 4, and it is possible to suppress a decrease in work efficiency when dividing the division target substrate 4.
Here, as a method of applying an external force to the division target substrate 4 in step S103, for example, a method of generating a bending stress inside the division target substrate 4 by applying a bending moment to the division target substrate 4 is used. Further, as a method of applying an external force to the division target substrate 4, a method of expanding the division target substrate 4 and generating a tensile stress inside the division target substrate 4 may be used.

(About the preliminary survey method in step S100)
Next, the prior survey method in step S100 in FIG. 4 will be described in detail.
FIG. 5 is a conceptual diagram for explaining a preliminary survey method.
As described above, in the preliminary survey in step S100, the position of the condenser lens 13 of the laser beam irradiation apparatus 10 in the Z-axis direction and the depth of the modified region formed on the division target substrate 4 placed on the stage 17 are determined. The relationship between the position in the vertical direction and the dimension in the depth direction of the modified region is determined.
In the laser beam irradiation device 10, the modified region formed on the division target substrate 4 by the distance by which the condenser lens 13 is lowered from the predetermined reference position in the Z-axis direction and the laser light condensed by the condenser lens 13. A linear relationship is established with the distance in the depth direction from the surface of the division target substrate 4.

That is, as shown in FIG. 5, first, a position in the Z-axis direction of the condenser lens 13 where the focal point of the laser light is located on the surface of the division target substrate 4 is obtained, and the position of the condenser lens 13 is set as a reference position P0. To do.
Then, the distance Z for lowering the condenser lens 13 from the reference position P0 and the distance L from the upper end of the modified region R formed on the division target substrate 4 by the condenser lens 13 to the surface of the division target substrate 4 Satisfies the linear relationship shown in the following formula (1). Further, a distance Z for lowering the condenser lens 13 from the reference position P0 and a distance M from the lower end of the modified region R formed on the division target substrate 4 by the condenser lens 13 to the surface of the division target substrate 4 Satisfies the linear relationship shown in the following formula (2).
L (Z) = aZ + b (1)
M (Z) = cZ + d (2)

Therefore, the condenser lens 13 is lowered from the reference position P0 to a position P1 below the distance Z1, and the modified region R1 is formed on the division target substrate 4 by the condenser lens 13. Then, a distance L1 from the surface of the division target substrate 4 to the upper end of the modified region R1 and a distance M1 from the surface of the division target substrate 4 to the lower end of the modified region R1 are measured.
Further, the condenser lens 13 is lowered from the reference position P0 to a position P2 below the distance Z2, and the reforming region R2 is formed on the division target substrate 4 by the condenser lens 13. Then, a distance L2 from the surface of the division target substrate 4 to the upper end of the modified region R2 and a distance M2 from the surface of the division target substrate 4 to the lower end of the modified region R2 are measured.
And the value of a and b is calculated | required from the distance Z1, the distance Z2, the distance L1, the distance L2, and the said Formula (1).

Further, the values of c and d are obtained from the distance Z1, the distance Z2, the distance M1, the distance M2, and the above equation (2).
Thereby, the distance Z for lowering the condenser lens 13 from the reference position P0, and the distance L from the upper end of the modified region R formed on the division target substrate 4 by the condenser lens 13 to the surface of the division target substrate 4; A linear function indicating the relationship is obtained. Further, a distance Z for lowering the condenser lens 13 from the reference position P0 and a distance M from the lower end of the modified region R formed on the division target substrate 4 by the condenser lens 13 to the surface of the division target substrate 4 A linear function indicating the relationship is obtained.

The relationship between the distance Z for lowering the condenser lens 13 from the reference position and the dimension H in the depth direction of the modified region R formed on the division target substrate 4 by the condenser lens 13 is expressed by the following equation (3). ).
H (Z) = M (Z) -L (Z) (3)
For example, the dimension H1 in the depth direction of the modified region R1 can be obtained by subtracting the distance L1 from the distance M1. Further, the dimension H2 in the depth direction of the modified region R2 is obtained by subtracting the distance L2 from the distance M2.

(First embodiment of the method for determining the arrangement of the modified region)
Next, the first embodiment of the method for determining the arrangement of the modified region in step S101 in FIG. 4 will be described in detail.
FIG. 6 is a schematic diagram illustrating an example of the arrangement of the modified regions on the substrate to be divided.
As described above, in the determination of the arrangement of the modified region in step S101, the arrangement of the modified region formed on the division target substrate 4 by the laser beam irradiation apparatus 10 is determined.
In this case, in the substrate dividing method according to the present invention, the modified regions are formed at a plurality of positions along the depth direction of the substrate to be divided 4.

In this embodiment, as shown in FIG. 6, the first modified region r <b> 1 is disposed on the surface portion of the division target substrate 4, and the second modified region r <b> 2 is disposed at the depth of the division target substrate 4. It is arranged at the center in the vertical direction.
Here, the surface portion of the division target substrate 4 on which the first modified region r1 is arranged is, for example, the surface side end portion of the division target substrate 4 and the division target substrate 4 in the first modified region r1. The position where the space | interval with the surface becomes 40-50 micrometers.

The central portion in the depth direction of the division target substrate 4 in which the second modified region r2 is disposed refers to the center of the dimension t in the depth direction of the division target substrate 4. In this case, the second modified region r2 is arranged such that the center C2 in the depth direction of the second modified region r2 is located at the center of the dimension t in the depth direction of the division target substrate 4.
Further, the central portion in the depth direction of the division target substrate 4 where the second modified region r2 is disposed is between the end portion on the back surface side of the first modified region r1 and the back surface of the division target substrate 4. It may be the center of the dimension D in the depth direction of the unmodified region present in FIG. In this case, the second modified region r2 has a center C2 in the depth direction of the second modified region r2 between the end portion on the back surface side of the first modified region r1 and the back surface of the substrate to be divided 4. It arrange | positions so that it may be located in the center of the dimension D of the depth direction of the unmodified area | region which exists in between.

The position of the center C2 in the depth direction of the second modified region r2 is the center of the dimension t in the depth direction of the substrate to be divided 4 or the end on the back side of the first modified region r1 and the object to be divided. Within the range of the distance obtained by dividing the dimension in the depth direction of the second modified region r2 into two equal parts from the center of the dimension D in the depth direction of the unmodified region existing between the back surface of the substrate 4 or It may be shifted downward.
In the substrate dividing method according to the present embodiment, it is possible to efficiently generate a surface crack in the division target substrate 4 by forming the first modified region r1 on the surface portion of the division target substrate 4.
In addition, by forming the second modified region r2 in the center of the division target substrate 4 in the depth direction, surface cracks generated in the division target substrate 4 by the first modified region r1 can be efficiently divided. It is possible to guide the substrate 4 so as to extend vertically toward the back surface side.

(Second embodiment of the method for determining the arrangement of the modified region)
Next, a second embodiment of the method for determining the arrangement of the modified region in step S101 in FIG. 4 will be described in detail.
FIG. 7 is a schematic diagram illustrating an example of the arrangement of the modified regions on the substrate to be divided.
As described above, in the determination of the arrangement of the modified region in step S101, the arrangement of the modified region formed on the division target substrate 4 by the laser beam irradiation apparatus 10 is determined.
In this case, in the substrate dividing method according to the present invention, the modified regions are formed at a plurality of positions along the depth direction of the substrate to be divided 4.

In this embodiment, the first modified region r1 is disposed on the front surface portion of the division target substrate 4, and the second modified region rn is disposed on the back surface side end of the first modified region r1. The dimension D in the depth direction of the unmodified region between the substrate and the rear surface of the division target substrate 4 is arranged at a position that equally divides n. Here, n is an integer of 2 or more (hereinafter the same).
In this case, in the second modified region rn, the center position Cn in the depth direction of the second modified region rn is such that the end on the back surface side of the first modified region r1 and the back surface of the division target substrate 4 Are arranged so that the dimension D in the depth direction of the unmodified region existing between them is divided into n equal parts.

However, the position of the center Cn in the depth direction of the second modified region rn is the unmodified region existing between the end portion on the back surface side of the first modified region r1 and the back surface of the division target substrate 4. The depth direction dimension D of the second modified region rn may be shifted upward or downward from a position where the depth direction dimension D of the second modified region rn is equally divided into two.
For example, when two modified regions are formed in the depth direction of the division target substrate 4, the first modified region r1 is arranged on the surface portion of the division target substrate 4 as shown in FIG. Further, the second modified region is located at a position where the dimension D in the depth direction of the unmodified region between the end portion on the back surface side of the first modified region r1 and the back surface of the division target substrate 4 is divided into two equal parts. Arrange r2.

Similarly, when three modified regions are formed in the depth direction of the division target substrate 4, the first modified region r1 is arranged on the surface portion of the division target substrate 4 as shown in FIG. Further, each of the first modified regions r1 is positioned at a position where the dimension D in the depth direction of the unmodified region between the end portion on the back surface side of the first modified region r1 and the back surface of the division target substrate 4 is divided into three equal parts. The second modified region r2 and the second modified region r3 are arranged.
In the substrate dividing method according to the present embodiment, the first modified region r <b> 1 is formed on the surface portion of the division target substrate 4, so that surface cracks can be efficiently generated in the division target substrate 4.

  Further, the second modified region rn divides the dimension D in the depth direction of the unmodified region between the end portion on the back surface side of the first modified region r1 and the back surface of the division target substrate 4 into n equal parts. It is formed in the position to do. That is, in the unmodified region between the end portion on the back surface side of the first modified region r1 and the back surface of the division target substrate 4, the n-1 second modified regions rn are arranged substantially evenly. Formed to be. As a result, the surface crack generated in the division target substrate 4 by the first modified region r1 can be efficiently guided to extend vertically toward the back surface side of the division target substrate 4.

(Third embodiment of the method for determining the arrangement of the modified region)
Next, a third embodiment of the method for determining the placement of the modified region in step S101 of FIG. 4 will be described in detail.
As described above, in the determination of the arrangement of the modified region in step S101, the arrangement of the modified region formed on the division target substrate 4 by the laser beam irradiation apparatus 10 is determined.
In this case, in the substrate dividing method according to the present invention, the modified regions are formed at a plurality of positions along the depth direction of the substrate to be divided 4.
In the present embodiment, as in the case of the second embodiment, the first modified region r1 is arranged on the surface portion of the substrate to be divided 4, and the second modified region rn is replaced with the first modified region rn. It arrange | positions in the position which divides the dimension D of the depth direction of the unmodified area | region between the edge part of the back surface side of the one modified area | region r1, and the back surface of the division | segmentation object board | substrate 4 into n equally.

Here, when the division target substrate 4 is divided by the laser scribing method, when the dimension in the depth direction of the unmodified region existing in the division target substrate 4 is increased, when the division target substrate 4 is divided by applying an external force. Then, shaving occurs in the unmodified region of the divided cross section. The unmodified region refers to a region in the division target substrate 4 that has not been modified by laser light irradiation.
Below, the experimental result which investigated about the relationship between the dimension of the depth direction of the unmodified | reformed area | region which exists in the division | segmentation object board | substrate 4, and the magnitude | size of the shaving which generate | occur | produces in a division | segmentation cross section is shown.

FIG. 8 is a diagram showing the relationship between the dimension in the depth direction of the unmodified region present in the substrate to be divided and the size of the shaving generated on the divided cross section, obtained by experiment. In addition, in FIG. 8, the state which looked at the division | segmentation cross section which divided | segmented the division | segmentation target board | substrate 4 from the side is shown. That is, in FIG. 8, the divided cross section is formed on the right side surface of the division target substrate 4 in the left-right direction and extends in the depth direction. In FIG. 8, the modified region formed along the depth direction of the division target substrate 4 is also shown on the front surface of the division target substrate 4 for convenience of explanation.
FIG. 8A shows a case in which a modified region is formed only on the surface portion of the substrate to be divided 4 and an unmodified region having a dimension in the depth direction of 1000 μm exists on the substrate to be divided 4. The experimental result when the external force is applied to and the division target substrate 4 is divided is shown.
As a result, as shown in FIG. 8A, it was confirmed that shaving having a maximum width of 250 μm occurred in the unmodified region portion in the divided cross section of the division target substrate 4.

FIG. 8B shows a state in which modified regions are formed on the front surface portion and the back surface portion of the substrate to be divided 4, respectively, and an unmodified region having a depth dimension of 700 μm exists on the substrate to be divided 4. An experimental result when the division target substrate 4 is divided by applying an external force to the division target substrate 4 is shown.
As a result, as shown in FIG. 8B, it was confirmed that shaving having a maximum width of 120 μm occurred in the unmodified region portion in the divided cross section of the substrate to be divided 4.
Furthermore, FIG.8 (c) shows the experimental result at the time of dividing | segmenting the division | segmentation object board | substrate 4 with the board | substrate division | segmentation method based on a present Example. That is, the first modified region is formed on the front surface portion of the division target substrate 4 and the depth of the unmodified region between the end portion on the back surface side of the first modified region and the back surface of the division target substrate 4 is formed. A second modified region is formed at a position where the vertical dimension is divided into two equal parts.

In this case, the division target substrate 4 includes an unmodified region having a dimension in the depth direction of 450 μm and an unmodified region having a dimension in the depth direction of 400 μm. Then, an external force was applied to the division target substrate 4 to divide the division target substrate 4.
As a result, as shown in FIG. 8C, the maximum width of the shaving generated on the divided cross section of the division target substrate 4 could be suppressed within 20 μm.
From the above experimental results, in particular, when the dimension in the depth direction of the unmodified region existing in the division target substrate 4 exceeds 500 μm, it occurs in the unmodified region portion of the divided cross section obtained by dividing the division target substrate 4. It was found that the sharpening was significant.

  Therefore, in the substrate dividing method according to the present embodiment, the first modified region r1 is disposed on the surface portion of the substrate to be divided 4, and the second modified region rn is disposed in the first modified region r1. It arrange | positions in the position which divides the dimension D of the depth direction of the unmodified area | region between the edge part of a back surface side, and the back surface of the division | segmentation target board | substrate 4 into n equally. In this case, the value of n is set so that the dimension in the depth direction of each unmodified region divided equally by the second modified region is 500 μm or less.

Hereinafter, a method for determining the arrangement of the modified regions according to the present embodiment will be specifically described.
FIG. 9 is a flowchart showing a method for determining the arrangement of the reforming regions.
In the method for determining the arrangement of the modified region according to the present embodiment, as shown in FIG. 9, first, the arrangement of the first modified region in the depth direction of the division target substrate 4 is determined (step S200).
In this case, the first modified region is disposed on the surface portion of the division target substrate 4.
Further, in the depth direction of the division target substrate 4, the distance between the lower end of the first modified region and the back surface of the division target substrate 4 is measured, thereby dividing the end portion on the back side of the first modified region and the division. The dimension D in the depth direction of the unmodified region existing between the back surface of the target substrate 4 is obtained (step S201).
Next, it is determined whether or not the value obtained by dividing the dimension D in the depth direction of the unmodified region into n equal parts is 500 μm or less (step S202). Here, the first value of n is 2.

In step S202, if the value obtained by dividing the dimension D in the depth direction of the unmodified region into n equal parts is not less than 500 μm (No), a new n is obtained by adding 1 to the current n value. Is set (step S203), and the determination of step S202 is performed again using the new value of n.
On the other hand, in step S202, when the value obtained by dividing the dimension D in the depth direction of the unmodified region into n equal parts is 500 μm or less (Yes), the end on the back surface side of the first modified region It is determined that an n-1 second modified region is formed in an unmodified region existing between the rear surface of the division target substrate 4 (step S204).
Next, the arrangement of n-1 second modified regions in the depth direction of the division target substrate 4 is determined (step S205).

In this case, the n-1 second modified region is a dimension in the depth direction of the unmodified region that exists between the back surface side end of the first modified region and the back surface of the division target substrate 4. It arrange | positions in the position which divides D into n equally.
Here, in the n-1 second modified region, the position of the center in the depth direction of the second modified region is the end portion on the back surface side of the first modified region and the back surface of the division target substrate 4. Are arranged so that the dimension D in the depth direction of the unmodified region existing between them is divided into n equal parts.
However, the position of the center in the depth direction of the second modified region is the depth of the unmodified region that exists between the end portion on the back surface side of the first modified region and the back surface of the division target substrate 4. The direction dimension D may be shifted upward or downward within a range of a distance obtained by dividing the dimension in the depth direction of the second modified region into two equal parts from the position where the dimension D in the direction is equally divided.
As described above, the arrangement of the modified regions in the depth direction of the division target substrate 4 is determined.

FIG. 10 is a conceptual diagram illustrating an example of the arrangement of the modified regions in the depth direction of the division target substrate.
As shown in FIG. 10, for example, in the depth direction of the division target substrate 4, an unmodified region existing between the end portion on the back surface side of the first modified region r <b> 1 and the back surface of the division target substrate 4. When the dimension D in the depth direction is 700 μm, the value obtained by dividing the dimension D in the depth direction of the unmodified region into two equal parts is 350 μm.
Therefore, since the value obtained by dividing the dimension D in the depth direction of the unmodified region into two equal parts is 500 μm or less, the end of the rear surface side of the first modified region r1 of the division target substrate 4 and the division target substrate 4 It is determined that one second modified region is to be formed in the unmodified region existing between the back surface.

In this case, the second modified region r2 has a dimension D in the depth direction of the unmodified region existing between the back surface side end portion of the first modified region r1 and the back surface of the division target substrate 4. It is formed at a position that bisects.
Similarly, for example, in the depth direction of the division target substrate 4, the depth direction of the unmodified region existing between the end portion on the back surface side of the first modified region r <b> 1 and the back surface of the division target substrate 4. When the dimension D is 1500 μm, the value obtained by dividing the dimension D in the depth direction of the unmodified region into three equal parts is 500 μm.
Therefore, since the value obtained by dividing the dimension D in the depth direction of the unmodified region into three equal parts is 500 μm or less, the end portion on the back surface side of the first modified region of the division target substrate 4 and the back surface of the division target substrate 4 It is determined that two second modified regions are formed in the unmodified region existing between the two.

In this case, the two second modified regions have the dimension D in the depth direction of the unmodified region existing between the back surface side end of the first modified region and the back surface of the division target substrate 4. Each is formed at a position to be divided into three equal parts.
In this way, by setting the value of n so that the dimension in the depth direction of each unmodified region divided into n by the second modified region in the division target substrate 4 is 500 μm or less. The occurrence of shaving on the divided cross section can be suppressed.
Here, in the present embodiment, the n-1 second modified region is formed in the unmodified region existing between the back surface side end portion of the first modified region and the back surface of the division target substrate 4. When deciding to do so, a configuration in which the dimension in the depth direction of the second modified region is not taken into consideration is adopted.

However, when deciding to form the n-1 second modified region in the unmodified region existing between the end portion on the back surface side of the first modified region and the back surface of the division target substrate 4. In addition, a configuration that considers the dimension in the depth direction of the second modified region may be adopted. In this case, in the determination in step S202 of FIG. 9, the value obtained by subtracting the dimension H in the depth direction of the n-1 second modified region from the dimension D in the depth direction of the unmodified region is divided into n equal parts. It is determined whether the value is 500 μm or less.
As described above, the method for cutting out the TFT substrate used for the liquid crystal display panel according to the embodiment of the present invention from the wafer-shaped substrate to be divided has been described. However, according to the method according to the embodiment, the cross-sectional accuracy is ensured. A liquid crystal display panel can be manufactured using the TFT substrate thus formed.

Here, various modifications can be made in the above embodiment.
For example, in one of the first to third embodiments of the modified region arrangement determining method in step S101, the depth direction dimension of the first modified region is set to the second modified region. You may employ | adopt the structure formed large compared with the dimension of a depth direction.
In the division target substrate 4, the back surface side of the first modified region is formed by forming the dimension in the depth direction of the first modified region larger than the dimension in the depth direction of the second modified region. The dimension in the depth direction of the unmodified region existing between the end of the substrate and the back surface of the substrate to be divided 4 is reduced.
Therefore, by reducing the dimension in the depth direction of the unmodified region existing in the division target substrate 4, it is possible to suppress the occurrence of shaving on the divided cross section.

Here, as a method of forming the first modified region with a large dimension in the depth direction, a method of lengthening the condensing region of the laser light by increasing the aberration of the laser light can be considered.
In this case, in the laser beam irradiation apparatus 10, the quartz glass plate 16 is used as the aberration correction means, the condensing region of the laser light is lengthened, that is, the region having a high energy density is lengthened, and the modified region is moved in the depth direction. Make it longer.
Further, as a method of forming the first modified region with a large dimension in the depth direction, a method of increasing the intensity of the laser beam may be employed.

It is a top view which shows the division | segmentation object board | substrate of the state before a division | segmentation. It is a conceptual diagram of the laser scribing method. It is a schematic block diagram which shows a laser beam irradiation apparatus. It is a flowchart which shows the board | substrate division | segmentation method concerning this invention. It is a conceptual diagram for demonstrating the method of a preliminary investigation. It is a schematic diagram which shows an example of arrangement | positioning of the modification area | region in a division | segmentation object board | substrate. It is a schematic diagram which shows an example of arrangement | positioning of the modification area | region in a division | segmentation object board | substrate. It is a figure which shows the relationship between the dimension of the depth direction of the unmodified | reformed area | region which exists in the division | segmentation object board | substrate calculated | required by experiment, and the magnitude | size of the shaving which generate | occur | produces in a division | segmentation cross section. It is a flowchart which shows the method of determining arrangement | positioning of a modification area | region. It is a conceptual diagram which shows an example of arrangement | positioning of the modification area | region in a division | segmentation object board | substrate.

Explanation of symbols

  4 Substrate to be divided, 10 Laser beam irradiation device, r1, r2, r3, rn, modified region.

Claims (6)

A substrate is divided by irradiating the substrate with laser light, forming a modified region in the substrate along a planned dividing line of the substrate, and applying an external force to the substrate on which the modified region is formed. A method of dividing a substrate,
A first modified region forming step of forming a first modified region at a depth position where cracks are generated on the surface of the substrate;
A second modified region is formed at a depth position that induces a crack generated on the surface of the substrate to extend vertically toward the back side of the substrate when an external force is applied to the substrate. A second modified region forming step;
A substrate dividing method characterized by comprising: In the first modified region forming step, the first modified region is formed on the surface portion of the substrate,
2. The substrate dividing method according to claim 1, wherein, in the second modified region forming step, the second modified region is formed at a central portion in the depth direction of the substrate. In the first modified region forming step, the first modified region is formed on the surface portion of the substrate,
In the second modified region forming step, the second modified region is formed in the depth direction of the unmodified region between the end portion on the back surface side of the first modified region and the back surface of the substrate. 2. The substrate dividing method according to claim 1, wherein the substrate is divided into n equal parts (n is an integer of 2 or more).   In the second modified region forming step, the value of n is set so that the dimension in the depth direction of each unmodified region divided by n by the second modified region is 500 μm or less. 4. The substrate dividing method according to claim 3, wherein the second modified region is formed.   The dimension in the depth direction of the first modified region is formed larger than the dimension in the depth direction of the second modified region. The substrate dividing method according to item.   6. A display device manufacturing method, wherein a display device substrate is divided from the substrate by the substrate dividing method according to any one of claims 1 to 5.

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