JP2015131732A - Method for cutting glass substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for cutting a glass substrate excellent in cutting accuracy and high in flexural strength.SOLUTION: The method for cutting a glass substrate comprises the steps of: irradiating a glass substrate having two translucent surfaces faced to each other in a substrate thickness direction with laser beam to form a heterogeneous area used as a cutting starting point inside the glass substrate in the substrate thickness direction along a scheduled cutting line of the glass substrate; and cutting the glass substrate along the scheduled cutting line using the heterogeneous area as the starting point. The laser beam being pulsed laser having time width of less than 400 pico seconds forms the heterogeneous area from a position spaced only constant distance from the translucent surface of the glass substrate on a laser beam incident side to a translucent surface faced on the laser beam incident side by passing once through the scheduled cutting line.

Description

  The present invention relates to a method for cutting a glass substrate.

  As a method for cutting a semiconductor substrate or the like, stealth dicing (registered trademark) is known (see, for example, Patent Document 1). In this cutting method, a laser beam having a wavelength that passes through a semiconductor substrate (for example, a silicon substrate) is condensed inside the semiconductor substrate to form a modified region (scratch region), and then external stress such as tape expansion is applied. Thus, the semiconductor substrate is cut by generating a crack starting from the modified region.

  In this cutting method, a modified region can be locally and selectively formed inside the semiconductor substrate without damaging the surface of the semiconductor substrate. Therefore, chipping or the like is performed on the surface of the semiconductor substrate which is a problem in general blade dicing. The occurrence of defects can be reduced. Also, unlike cutting, there are few problems such as dust generation. For this reason, in recent years, not only semiconductor substrates but also glass substrates have been widely used.

JP 2009-135342 A

In the modified region formed inside the glass substrate by the laser beam, thermal stress is generated with the irradiation of the laser beam, thereby causing many cracks. When the glass substrate is cut along the planned cutting line, the crack is extended to the glass substrate surface starting from this crack.
However, the cracks in the modified region are not all aligned in a certain direction. Therefore, when extending the crack by applying external stress to cut the glass substrate, the extension direction of the crack is not constant, and the ridgeline of the glass substrate (the line where the cut surface of the glass substrate and the translucent surface intersect) May meander. Depending on the use of the glass substrate, when the glass substrate is combined with another member, the glass substrate may be positioned using the ridgeline or side surface of the glass substrate. Therefore, it is preferable that the ridgeline of the glass substrate has a linearity equivalent to that obtained by cutting with another cutting method such as a dicing blade.

  The present invention has been made in order to solve the above-mentioned problems, and by forming a heterogeneous region using a laser beam inside a glass substrate and cutting from the heterogeneous region as a starting point, good cutting accuracy and high It aims at providing the cutting method of a glass substrate provided with bending strength.

  In the method for cutting a glass substrate according to the present invention, the glass substrate having two light-transmitting surfaces facing each other in the plate thickness direction is irradiated with a laser beam, and the plate thickness of the glass substrate is cut along the planned cutting line of the glass substrate. A method of cutting a glass substrate comprising: forming a heterogeneous region serving as a cutting start point in a direction; and cutting the glass substrate along the planned cutting line using the heterogeneous region as a starting point, The laser beam is a pulse laser with a time width of less than 400 picoseconds, and the laser beam passes through the scheduled cutting line once, so that the laser beam is incident on the side of the glass substrate on which the laser beam is incident. A heterogeneous region is formed from a position separated by a certain distance to a translucent surface facing the side on which the laser beam is incident.

  In the method for cutting a glass substrate according to the present invention, the glass substrate having two light-transmitting surfaces facing each other in the plate thickness direction is irradiated with a laser beam, and the plate thickness of the glass substrate is cut along the planned cutting line of the glass substrate. A method of cutting a glass substrate comprising: forming a heterogeneous region serving as a cutting start point in a direction; and cutting the glass substrate along the planned cutting line using the heterogeneous region as a starting point, The laser beam is a pulse laser having a time width of less than 400 picoseconds, and the laser beam passes through the scheduled cutting line once, so that the laser beam is spaced apart from the light transmitting surface of the glass substrate by a certain distance. A heterogeneous region is formed between a position spaced from the other light-transmitting surface by a certain distance.

  In the method for cutting a glass substrate according to the present invention, the glass substrate having two light-transmitting surfaces facing each other in the plate thickness direction is irradiated with a laser beam, and the plate thickness of the glass substrate is cut along the planned cutting line of the glass substrate. A method of cutting a glass substrate comprising: forming a heterogeneous region serving as a cutting start point in a direction; and cutting the glass substrate along the planned cutting line using the heterogeneous region as a starting point, The laser light is a pulse laser having a time width of less than 400 picoseconds, and the laser light passes through the scheduled cutting line once to form a heterogeneous region in the entire plate thickness direction of the glass substrate. Features.

  According to the present invention, since a crack in a heterogeneous region formed inside the glass substrate is very small or does not exist, it is possible to obtain a glass substrate having good dimensional accuracy and high bending strength after cutting.

It is a schematic explanatory drawing of the cutting method of the glass substrate which concerns on the 1st Embodiment of this invention. It is a schematic explanatory drawing of the cutting method of the glass substrate which concerns on the 2nd Embodiment of this invention. It is a schematic explanatory drawing of the cutting method of the glass substrate which concerns on the 3rd Embodiment of this invention.

[First Embodiment]
A method for cutting the glass substrate 1 according to the first embodiment of the present invention (hereinafter referred to as a first cutting method) will be described with reference to FIG. FIG. 1A is a plan view showing an outline of the first cutting method. FIG. 1B is a cross-sectional view showing an outline of the first cutting method. A 1st cutting method is related with the cutting | disconnection of the glass substrate 1 provided with two translucent surfaces which oppose a plate | board thickness direction, as shown in FIG.

  In the first cutting method, the glass substrate 1 having two light-transmitting surfaces facing each other in the plate thickness direction is irradiated with the laser light 2, and the glass substrate 1 is cut along the planned cutting line L in the plate thickness direction of the glass substrate 1. The process of forming the heterogeneous area | region 3 used as a cutting | disconnection start point inside is provided with the process of cut | disconnecting the glass substrate 1 along the scheduled cutting line L from the heterogeneous area | region 3 as a starting point.

  The step of forming a heterogeneous region serving as a cutting start point in the thickness direction of the glass substrate 1 is performed by aligning the condensing point inside the glass substrate 1 and irradiating the laser beam 2 with the heterogeneous region inside the glass substrate 1. Region 3 is formed. And the heterogeneous area | region 3 is continuously formed by moving the laser beam irradiation apparatus 10 to the moving direction D along the scheduled cutting line L, and changing the irradiation position of the laser beam 2. FIG.

When the laser beam 2 having a predetermined energy intensity is irradiated so as to be condensed inside the glass substrate 1, high energy is given to the portion where the laser beam 2 is collected in a very short time by the laser beam 2. The Therefore, the portion where the laser beam 2 is condensed is weakened in a state where cracks due to thermal stress hardly occur. Although this phenomenon has not been confirmed in detail, it is considered that the glass structure is partially cut at the molecular level in the portion where the laser beam 2 is condensed by the energy of the laser beam 2.
The heterogeneous region in the present invention refers to a region where some property change has occurred in the glass substrate 1 due to the irradiation of the laser beam 2. The region where some property change occurs refers to a region where the above-described weakening occurs or a region where an optical change (such as a refractive index) occurs before and after irradiation with the laser beam 2.

  The first cutting method is characterized by the range of the heterogeneous region 3 in the step of forming the heterogeneous region. In this step, when the laser beam 2 passes through the cutting line L of the glass substrate 1 once, only a fixed distance 5 (a distance exceeding zero) from the light transmitting surface 6 on the side on which the laser beam 2 of the glass substrate 1 is incident. The heterogeneous region 3 is formed from the separated position to the light transmitting surface 7 facing the side on which the laser beam 2 is incident. In other words, the heterogeneous region 3 is not formed on the light transmitting surface 6 on the side of the glass substrate 1 on which the laser light 2 is incident, and the distance from the light transmitting surface 6 by a fixed distance 5 to the other light transmitting surface 7. A heterogeneous region 3 is formed between them. Therefore, the processing trace by the laser beam 2 does not occur on the ridge line on the side of the cut glass substrate 1 on which the laser beam 2 is incident. Therefore, when the glass substrate 1 is cut in the next cutting step, a highly linear ridge line can be obtained.

  As the laser beam 2, a pulse laser having a time width of less than 400 picoseconds is used. The reason is that if the time width of the laser beam 2 exceeds 400 picoseconds, a plurality of cracks due to thermal stress occur in the glass substrate 1 formed by the laser beam 2. As the laser beam 2, a picosecond laser or a femtosecond laser may be used.

  The laser beam 2 is preferably corrected so as to have a condensing shape 4 having a larger width in the plate thickness direction of the glass substrate 1 than the condensing shape obtained due to the refractive index of the glass substrate 1. Usually, if the focal shape of the laser beam 2 is not controlled, the condensing shape is somewhat deformed from the circular system due to the refractive index of the glass substrate 1. However, when the plate thickness dimension of the glass substrate 1 is sufficiently thicker than the condensing shape of the laser beam 2, it is necessary to scan the laser beam 2 a plurality of times while changing the position in the plate thickness direction along the planned cutting line L. is there. On the other hand, by controlling the laser beam 2 to a light condensing shape 4 that is long in the thickness direction of the glass substrate 1, it is possible to form a desired heterogeneous region 3 by scanning the laser beam 2 once. .

  The condensing shape of the laser beam 2 is controlled by a method of controlling the laser beam 2 by passing it through a hologram lens, and by passing the laser beam 2 through a phase modulation type liquid crystal spatial light modulator (LCOS-SLM). You may use well-known methods, such as a method.

As the laser beam 2, a multi-focus laser beam divided into a plurality of focal points may be used. As a result, the laser beam 2 is scanned once along the planned cutting line L in the same manner as the laser beam 2 having the condensing shape 4 that is long in the plate thickness direction in which the condensing shape is controlled. 3 can be formed. The multi-focus laser divided into a plurality of focal points is obtained by dividing one laser beam so that a plurality of condensing points of the laser beam 2 exist in the thickness direction of the glass substrate 1.
The laser beam 2 can be divided into a plurality of focal points by a known method such as using an optical element such as a prism.

  The heterogeneous region 3 may have a width in the thickness direction as follows depending on the time width of the laser beam 2 to be used. In the first cutting method, the heterogeneous region 3 is formed on the light transmitting surface 6 facing the side on which the laser beam 2 is incident. Therefore, the width in the thickness direction of the heterogeneous region 3 refers to the distance from the light transmitting surface 7 facing the side on which the laser beam 2 is incident.

When a pulse laser having a time width of 40 picoseconds or more and less than 400 picoseconds is used as the laser beam 2, the width in the thickness direction of the heterogeneous region 3 is 50% to 80% of the thickness dimension. Is preferred.
When a pulse laser having a time width of 400 femtoseconds or more and less than 40 picoseconds is used as the laser light 2, the width in the thickness direction of the heterogeneous region 3 is 60% to 90% of the thickness dimension. Is preferred.
When a pulse laser having a time width of less than 400 femtoseconds is used as the laser beam 2, the width in the plate thickness direction of the heterogeneous region 3 is preferably 70% to 99% of the plate thickness dimension.

The step of cutting the glass substrate 1 along the planned cutting line L starting from the heterogeneous region 3 includes a method of bending by applying a bending stress so that the light-transmitting surface 6 of the glass substrate 1 has a convex shape, It is possible to use a known cutting method such as a method of cutting by sticking the glass substrate 1 to a sticky adhesive tape and pulling the adhesive tape in the plane direction of the glass substrate 1.
Since the heterogeneous region 3 generated in the process of forming the heterogeneous region is weakened and cracks are small or do not exist, the glass substrate 1 is not affected by the direction of the crack and is along the thickness direction in which the heterogeneous region 3 exists. It is cut straight. Therefore, the linearity of the glass substrate 1 after cutting is high and the dimensional accuracy is good.

  According to the first cutting method, since the heterogeneous region 3 is not formed on the light transmitting surface 6 on the incident side of the laser light 2, the ridgeline of the light transmitting surface 6 on the incident side of the laser light 2 has good linearity. . Further, the ridgeline of the light transmitting surface 6 on the incident side of the laser beam 2 is not damaged by the laser beam 2. Thereby, the glass with the high intensity | strength (bending strength) at the time of bending the glass substrate 1 is obtained. In addition, the cut surface of the glass substrate 1 (the surface between the translucent surface 6 and the translucent surface 7 on which the heterogeneous region 3 is formed) is almost free from cracks due to the irradiation of the laser beam 2 and has high cleanliness. The substrate 1 can be obtained.

[Second Embodiment]
A method for cutting the glass substrate 1 according to the second embodiment of the present invention (hereinafter referred to as a second cutting method) will be described with reference to FIG. FIG. 2A is a plan view showing an outline of the second cutting method. FIG. 2B is a cross-sectional view showing an outline of the second cutting method. A 2nd cutting method is related with the cutting | disconnection of the glass substrate 1 provided with two translucent surfaces which oppose a plate | board thickness direction, as shown in FIG. In the present embodiment, the same parts as those in the first embodiment are denoted by the same reference numerals, and redundant description is omitted.

The second cutting method is characterized by the range of the heterogeneous region 3 in the step of forming the heterogeneous region, and is different from the first cutting method.
In this process, when the laser beam 2 passes through the scheduled cutting line L of the glass substrate 1 once, the laser beam 2 is separated from one translucent surface 6 of the glass substrate 1 by a fixed distance 5 (distance exceeding zero) to the other. The heterogeneous region 3 is formed between the positions separated from the light transmitting surface 7 by a certain distance 8 (a distance exceeding zero). That is, the heterogeneous region 3 is not formed on each of the light transmitting surface 6 on the side of the glass substrate 1 on which the laser light 2 is incident and the light transmitting surface 7 facing the glass substrate 1, and are separated from one light transmitting surface 6 by a certain distance 5. The heterogeneous region 3 is formed between the position and a position separated from the other light transmitting surface 7 by a fixed distance 8. Therefore, the processing trace by the laser beam 2 does not occur on the ridge line of the glass substrate 1 after cutting. Therefore, when the glass substrate 1 is cut in the next cutting step, a highly linear ridge line can be obtained.

  The heterogeneous region 3 may have a width in the thickness direction as follows depending on the time width of the laser beam 2 to be used. In the second cutting method, the heterogeneous region 3 is formed between a position spaced from the one light transmitting surface 6 by a fixed distance 5 and a position spaced from the other light transmitting surface 7 by a fixed distance 8. Therefore, the width in the thickness direction of the heterogeneous region 3 refers to a distance from a position separated from one light transmitting surface 6 by a fixed distance 5 to a position spaced from the other light transmitting surface 7 by a fixed distance 8. Is. Further, the width of the heterogeneous region 3 may be in the center in the thickness direction as long as it is within the range described later, or may be unevenly distributed on one of the light-transmitting surfaces.

When a pulse laser having a time width of 40 picoseconds or more and less than 400 picoseconds is used as the laser beam 2, the width in the thickness direction of the heterogeneous region 3 is 50% to 80% of the thickness dimension. Is preferred.
When a pulse laser having a time width of 400 femtoseconds or more and less than 40 picoseconds is used as the laser light 2, the width in the thickness direction of the heterogeneous region 3 is 60% to 90% of the thickness dimension. Is preferred.
When a pulse laser having a time width of less than 400 femtoseconds is used as the laser beam 2, the width in the plate thickness direction of the heterogeneous region 3 is preferably 70% to 99% of the plate thickness dimension.

  In the second cutting method, the type and shape of the laser beam 2 to be used and the step of cutting the glass substrate 1 are the same as in the first cutting method.

  According to the second cutting method, since the heterogeneous region 3 is not formed on each light-transmitting surface (the light-transmitting surface 6 and the light-transmitting surface 7) of the glass substrate 1, the ridgeline of the glass substrate 1 has good linearity. . Further, the ridgeline of the glass substrate 1 is not damaged by the laser light 2. Thereby, the glass with the high intensity | strength (bending strength) at the time of bending the glass substrate 1 is obtained. In addition, the cut surface of the glass substrate 1 (the surface between the translucent surface 6 and the translucent surface 7 on which the heterogeneous region 3 is formed) is almost free from cracks due to the irradiation of the laser beam 2 and has high cleanliness. The substrate 1 can be obtained.

[Third Embodiment]
A glass substrate cutting method (third cutting method) according to the third embodiment of the present invention will be described with reference to FIG. FIG. 3A is a plan view showing an outline of the third cutting method. FIG. 3B is a cross-sectional view showing an outline of the third cutting method. A 3rd cutting method is related with the cutting | disconnection of the glass substrate 1 provided with two translucent surfaces which oppose a plate | board thickness direction, as shown in FIG. In the present embodiment, the same parts as those in the first embodiment are denoted by the same reference numerals, and redundant description is omitted.

The third cutting method has a feature in the range of the heterogeneous region 3 in the step of forming the heterogeneous region, and is different from the first cutting method.
In this step, when the laser beam 2 passes through the scheduled cutting line L of the glass substrate 1 once, the heterogeneous region 3 is formed in the entire plate thickness direction of the glass substrate 1. Therefore, when the glass substrate 1 is cut in the next cutting step, a highly linear ridge line can be obtained.

In the third cutting method, the laser beam 2 is irradiated so that the heterogeneous region 3 is formed in the entire thickness direction of the glass substrate 1. Therefore, if the heterogeneous region 3 is formed as described above, the width of the laser light 2 in the thickness direction may be smaller or larger than the thickness direction of the glass substrate 1. When the laser beam 2 that irradiates a width larger than the thickness direction of the glass substrate 1 is used, fine adjustment of the focal point of the laser beam 2 becomes unnecessary, so that productivity can be increased.
In the third cutting method, the type of laser light 2 to be used and the step of cutting the glass substrate 1 are the same as in the first cutting method.

  According to the 3rd cutting method, since the heterogeneous area | region 3 is formed in the plate | board thickness direction whole region of the glass substrate 1, the ridgeline of the glass substrate 1 has favorable linearity. Further, the ridgeline and the cut surface (the surface between the translucent surface 6 and the translucent surface 7 on which the heterogeneous region 3 is formed) of the glass substrate 1 are hardly cracked by the irradiation of the laser beam 2. Therefore, the glass substrate 1 with high cleanliness and high strength (bending strength) when bent can be obtained.

In the cutting methods (including the first to third cutting methods) of the present invention, the glass substrate 1 has a softening point of 300 to 1000 ° C., a fracture toughness of 0.1 to 0.74 MPa · m ^1/2 , and 50 ° C. It is preferable to provide any one or more of an average thermal expansion coefficient of ˜300 ° C. of 65 to 200 × 10 ⁻⁷ / K.

When the fracture toughness of the glass substrate 1 exceeds 0.74 MPa · m ^1/2 , when the heterogeneous region 3 is formed on the glass substrate 1 with the laser light 2, the heterogeneous region 3 is hardly generated, and thus it is difficult to cut the glass substrate 1. . Furthermore, when the glass substrate 1 is cut from the heterogeneous region 3, cracks are difficult to extend in the thickness direction, so that the glass substrate 1 is forcibly cut and the cut surface of the glass substrate 1 becomes rough, and the dimensional accuracy is improved. Deteriorate.

On the other hand, when the fracture toughness of the glass substrate 1 is less than 0.1 MPa · m ^1/2 , when the heterogeneous region 3 is formed on the glass substrate 1 with the laser light 2, the number of occurrences of cracks in the heterogeneous region 3 increases. For this reason, there is a risk that a crack reaching the light-transmitting surface of the glass substrate 1 from the heterogeneous region 3 of the glass substrate 1 may be formed, causing a problem that the cut glass substrate 1 is easily chipped or broken. Moreover, since the crack is easily extended excessively starting from the heterogeneous region 3, the crack extends in a direction other than the plate thickness direction, and the cut surface of the glass substrate 1 becomes rough. Thereby, the dimensional accuracy of the glass substrate 1 is bad, and there exists a possibility that bending strength may become low. Further, if the fracture toughness is less than 0.1 MPa · m ^1/2 , even if a crack present on the cut surface of the glass substrate 1 is very small, it causes breakage, and the bending strength of the glass substrate 1 after the cut May not be practical.
Fracture toughness of the glass substrate 1 is preferably 0.15~0.65MPa ^{· m 1/2,} more preferably ^{0.2~0.6MPa · m 1/2, 0.2~0.5MPa · m} 1 ^{/ 2} is more preferable.

Moreover, when the average thermal expansion coefficient in the temperature range of 50-300 degreeC of the glass substrate 1 exceeds 200 * 10 < ^-7 > / K, when forming the heterogeneous area | region 3 in the glass substrate 1 with the laser beam 2, the heterogeneous area | region 3 Are excessively formed, and the dimensional accuracy and bending strength of the glass substrate 1 after cutting are significantly reduced. On the other hand, when the average thermal expansion coefficient in the temperature range of 50 to 300 ° C. of the glass substrate 1 is less than 65 × 10 ⁻⁷ / K, when forming the heterogeneous region 3 on the glass substrate 1 with the laser beam 2, the heterogeneity Since the region 3 is difficult to be formed, it is difficult to cut the glass substrate 1.
The average thermal expansion coefficient in the temperature range of 50 to 300 ° C. of glass substrate 1 is preferably 75~180 × ^{10 -7} / K, more preferably ^{90~150 × 10 -7 / K, 110~140} × 10 -7 / K is more preferable.

  Moreover, when the softening point of the glass substrate 1 exceeds 1000 ° C., when the heterogeneous region 3 is formed on the glass substrate 1 with the laser light 2, the heterogeneous region 3 is difficult to be formed, so that the glass substrate 1 may be difficult to cut. is there. On the other hand, when the softening point of the glass substrate 1 is less than 300 ° C., when the heterogeneous region 3 is formed on the glass substrate 1 with the laser light 2, the cracks in the heterogeneous region 3 become excessive, and the dimensions of the glass substrate 1 after cutting are large. Accuracy and bending strength are significantly reduced.

  Any glass having any composition may be used as the glass substrate 1 as long as these physical properties can be obtained. Examples thereof include fluorophosphate glass, phosphate glass, soda lime glass, borosilicate glass, aluminosilicate glass, and alkali aluminosilicate glass.

  The glass substrate 1 can be used as glass for various applications. In the cutting method of the present invention, a glass substrate 1 with high dimensional accuracy and bending strength can be obtained, and therefore, it can be particularly preferably used for glass of an optical element having a relatively small size, but is not limited thereto. .

  The present invention can obtain a glass substrate with good dimensional accuracy and high bending strength after cutting.

  DESCRIPTION OF SYMBOLS 1 ... Glass substrate, 2 ... Laser beam, 3 ... Different region, 4 ... Condensation shape of laser beam, 5 ... Distance from light transmission surface of laser beam incident side to foreign region, 6 ... Laser beam incident side Light-transmitting surface, 7... Light-transmitting surface facing the light-transmitting surface on the laser beam incident side, 8... Distance from the light-transmitting surface facing the light-transmitting surface on the laser beam incident side to the heterogeneous region, 10. Irradiation device, L ... planned cutting line, D ... moving direction of laser light.

Claims (7)

A glass substrate having two light-transmitting surfaces facing each other in the plate thickness direction is irradiated with laser light, and a heterogeneous region serving as a cutting start point is formed inside the plate thickness direction of the glass substrate along a planned cutting line of the glass substrate. And a process of
A step of cutting the glass substrate along the scheduled cutting line starting from the heterogeneous region, and a method of cutting a glass substrate comprising:
The laser beam is a pulse laser having a time width of less than 400 picoseconds,
The laser beam passes through the scheduled cutting line once, so that the laser beam is opposed to the side on which the laser beam is incident from a position separated from the light transmitting surface on the side on which the laser beam is incident on the glass substrate. A method for cutting a glass substrate, comprising forming a heterogeneous region up to a light-transmitting surface. A glass substrate having two light-transmitting surfaces facing each other in the plate thickness direction is irradiated with laser light, and a heterogeneous region serving as a cutting start point is formed inside the plate thickness direction of the glass substrate along a planned cutting line of the glass substrate. And a process of
A step of cutting the glass substrate along the scheduled cutting line starting from the heterogeneous region, and a method of cutting a glass substrate comprising:
The laser beam is a pulse laser having a time width of less than 400 picoseconds,
The laser beam passes through the scheduled cutting line once, so that the laser beam is dissimilar between a position spaced from the one light-transmitting surface of the glass substrate by a certain distance and a position spaced from the other light-transmitting surface by a certain distance. A method for cutting a glass substrate, comprising forming a region. The width of the heterogeneous region in the thickness direction is
In the case of a pulse laser having a time width of the laser beam of 40 picoseconds or more and less than 400 picoseconds, it is 50% to 80% of the plate thickness dimension,
In the case of a pulse laser having a time width of the laser beam of 400 femtoseconds or more and less than 40 picoseconds, it is 60% to 90% of the plate thickness dimension,
3. The method for cutting a glass substrate according to claim 1, wherein the time width of the laser beam is 70% to 99% of the plate thickness dimension in the case of a pulse laser having a time width of less than 400 femtoseconds. A glass substrate having two light-transmitting surfaces facing each other in the plate thickness direction is irradiated with laser light, and a heterogeneous region serving as a cutting start point is formed inside the plate thickness direction of the glass substrate along a planned cutting line of the glass substrate. And a process of
A step of cutting the glass substrate along the scheduled cutting line starting from the heterogeneous region, and a method of cutting a glass substrate comprising:
The laser beam is a pulse laser having a time width of less than 400 picoseconds,
The method for cutting a glass substrate, wherein the laser light passes through the scheduled cutting line once to form a heterogeneous region in the entire thickness direction of the glass substrate.   The laser beam is corrected so as to have a condensing shape having a larger width in the thickness direction of the glass substrate as compared with a condensing shape obtained due to a refractive index of the glass substrate. The method for cutting a glass substrate according to any one of claims 1 to 4.   The method for cutting a glass substrate according to any one of claims 1 to 4, wherein the laser beam includes a plurality of condensing points in a thickness direction of the glass substrate. The glass substrate has a softening point of 300 to 1000 ° C., a fracture toughness of 0.1 to 0.74 MPa · m ^1/2 , and an average thermal expansion coefficient of 65 to 200 × 10 ⁻⁷ in a temperature range of 50 ° C. to 300 ° C. Any one or more of / K is provided, The cutting method of the glass substrate of any one of Claim 1 thru | or 6 characterized by the above-mentioned.

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