JP2007105888A - First crack forming method of fragile material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a simple method for forming the first crack only to a scheduled splitting line of a fragile material along the thickness direction of the fragile material when a first crack for splitting the fragile material is formed. <P>SOLUTION: In the first crack forming method of the fragile material 1 for forming the first crack 10 to the fragile material 1 when the fragile material 1 is split, the place of the material side edge part 1a crossing the scheduled splitting line K of the fragile material 1 is irradiated with a pulse laser L<SB>B</SB>of an ultraviolet region in a semicircular shape, and the material at that place is melted or sublimed to form the first crack to the place of the material side edge part 1a. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for forming initial cracks when cleaving brittle materials such as glass.

  When a brittle material such as glass, ceramic, or semiconductor wafer is cleaved, as a conventional method for forming an initial crack that is a starting point of cleaving, as shown in FIG. A mechanical technique has been adopted in which a diamond or cemented carbide cutter 110 is pressed against the portion of the material side edge portion 100a to form the initial crack 102 at the portion of the side edge portion 100a.

  However, in this case, when the initial crack 102 is formed, fine glass powder (cullet) is generated, which may hinder subsequent cleaving. In addition, the initial crack 102 generated in the material side edge portion 100a by pressing the cutter 110 extends radially as shown in the enlarged view of FIG. A microcrack has occurred (in the figure, only the microcrack 102a is along the direction of the cleaving line 101). For this reason, the cleaving portion immediately after the initial crack may not be cleaved accurately along the cleaving line 101.

  Therefore, in recent years, a method for forming an initial crack using a laser beam has been developed (see International Publication No. 2003/008352 pamphlet). In what is shown in the pamphlet, with the material surface heated, the material surface is irradiated with the short wavelength of the YAG laser, thereby melting or sublimating the material side edge that intersects the cleaved line, An initial crack is formed.

However, in the method shown in the above publication, it is necessary to preheat the material surface prior to the formation of the initial crack, which makes the procedure somewhat troublesome.
International Publication No. 2003/008352 pamphlet (see FIG. 2A)

  The problem to be solved by the present invention is to provide a simple method for generating an initial crack only in a direction along the planned cutting line of the material and the thickness direction of the material when forming the initial crack for breaking the brittle material. Trying to provide.

  The invention of claim 1 of the present application is an initial crack forming method for forming an initial crack for cleaving a brittle material in a brittle material, and an ultraviolet ray is applied to a portion of the material side edge that intersects the planned fracture line of the material. By irradiating the region with a pulse laser to melt or sublimate the material at the relevant location, an initial crack is formed at the relevant location at the material side edge.

  In the first aspect of the present invention, since the initial crack is formed by melting or sublimating a part of the material using a pulse laser, the material is cut in a direction different from the planned cutting line and the direction along the thickness direction of the material. It is possible to generate a single initial crack only in a direction along the material cutting line and the thickness direction of the material without generating the initial crack. In addition, in this case, since a pulse laser in the ultraviolet region with a short wavelength is used, a high-energy laser beam can be irradiated to the portion on the side edge of the material that intersects the planned cutting line of the material. Thereby, it is not necessary to preheat the material before forming the initial crack, and as a result, the process of forming the initial crack can be simplified.

  In the invention of claim 2, the pulse laser has a circular or elliptical laser spot, and the formation of the initial crack is caused by irradiating the semicircular portion of the laser spot to the portion of the material side edge portion. Has been done.

  In this case, the initial crack formed at the above-mentioned portion of the material side edge portion has a substantially V-shaped or substantially U-shaped shape that opens to the outside of the material. In addition, the material can be easily cleaved.

  In the invention of claim 3, the pulse laser is a YAG laser whose wavelength is converted into the ultraviolet region.

  In the invention of claim 4, the pulse laser is an excimer laser.

  As described above, according to the present invention, by using a pulse laser in the ultraviolet region with a short wavelength, it is possible to irradiate a portion of the material side edge that intersects the planned cutting line of the material with a high energy laser beam. There is no need to preheat the material before forming the initial crack, and the initial crack forming process can be simplified.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
1 to 4 are diagrams for explaining an initial crack forming method according to an embodiment of the present invention. FIG. 1 is a partial plan view of a brittle material to which the initial crack forming method is applied, and FIG. 2 is a brittle material. FIG. 3 is a partial plan view thereof, and FIG. 4 is a side view thereof.

  In the initial crack formation method according to the present embodiment, as shown in FIG. 1, a pulse laser in the ultraviolet region is irradiated onto a point A intersecting the cleaving line K of the material 1 on the side edge 1 a of the brittle material 1. . As this pulse laser, for example, a YAG laser wavelength-converted into the ultraviolet region is used. Specifically, a third harmonic wave (355 nm) generated from the fundamental wavelength (1064 nm) by converting the wavelength of an Nd: YAG laser was used. An excimer laser may be used.

The pulsed laser has a circular or elliptical laser spot L _B, upon irradiation of the laser beam to match the center of the laser spot L _B and the point A. Thus, as shown in FIG. 1, a semicircular portion of the laser spot L _B is irradiated to the point A and its neighboring region.

  Here, since the pulse laser to be irradiated has a short wavelength in the ultraviolet region, it is possible to irradiate the point A on the side edge portion 1a of the material 1 and the vicinity thereof with a high energy laser beam.

By irradiation with such a pulse laser, a part of the material 1 is melted or sublimated at the point A and the vicinity thereof, and then the processed surface is contracted, and as shown in FIG. 2, on the side edge 1a. An initial crack 10 was formed at a location intersecting with the planned cutting line K of the material 1. Length along the planned cutting line K of the first crack 10 was less than 20μm of diameter approximately the same laser spot L _B. Further, no microcracks were generated around the initial crack 10.

  In this case, since the initial crack 10 is formed by melting or sublimating a part of the material 1 using a pulse laser, the direction is different from the direction of the cutting line K of the material 1 and the thickness direction of the material 1. The first crack 10 can be generated only in the direction along the planned cutting line K and in the thickness direction of the material 1 without generating the initial crack 10.

  In addition, in this case, since a pulse laser in the ultraviolet region with a short wavelength is used, it is possible to irradiate the point A of the material side edge portion 1a intersecting the planned cutting line K of the material 1 with a high energy laser beam. Thereby, it is not necessary to preheat the material 1 before the initial crack 10 is formed, and as a result, the process of forming the initial crack 10 can be simplified.

Further, in this case, since the formation of the first crack, is performed by irradiating the A and its neighboring region point on the semicircular portion of the material-side edge 1a of the laser spot L _B, the material-side edge 1a The initial crack 10 formed in FIG. 3 has a substantially V-shaped or substantially U-shaped shape that opens to the outside of the material 1 (see FIGS. 3 and 4). This makes it easy to cleave the material during subsequent cleaving (including both mechanical cleaving and thermal cleaving).

In the above-described embodiment, an example in which an initial crack is formed using a pulse laser in the ultraviolet region has been shown. However, as shown in FIG. it is also possible to store heat stress inside the material is irradiated along the planned cutting line K of (in the figure, region H _S indicates the storage region of the thermal stress). In this case, by suppressing the output of the pulse laser, melting or sublimation of the material does not occur at the time of laser beam irradiation, and then the cooling point is moved along the cleaving line K, The thermal cleaving along the cleaving line K can be executed accurately and quickly.

1 is a partial plan view of a brittle material to which an initial crack formation method according to an embodiment of the present invention is applied. It is a perspective fragmentary view of the brittle material to which the said initial crack formation method was applied. FIG. 3 is a partial plan view of the brittle material (FIG. 2). It is a side view of the said brittle material (FIG. 2). It is a figure for demonstrating a mode that the thing which suppressed the output of the pulsed laser of the ultraviolet region used with the said initial crack formation method is irradiated along the cleaving line of material, and a thermal stress is accumulate | stored inside a material. It is a figure for demonstrating the conventional initial crack formation method. It is an enlarged view of the initial crack formed by the conventional method.

Explanation of symbols

1: Brittle material 1a: Side edge 10: Initial crack

L _B : Laser spot K: Scheduled cutting line

Claims (4)

An initial crack forming method for forming an initial crack in a brittle material for cleaving the brittle material,
By irradiating a portion of the material side edge that intersects the material's planned cutting line with a pulsed laser in the ultraviolet region to melt or sublimate the material at that portion, an initial crack is formed at that portion of the side edge. Like,
A method for forming an initial crack in a brittle material. In claim 1,
The pulse laser has a circular or elliptical laser spot, and the formation of the initial crack is performed by irradiating a semicircular portion of the laser spot to the corresponding portion of the side edge. ,
A method for forming an initial crack in a brittle material. In claim 1,
The pulse laser is a YAG laser wavelength-converted to the ultraviolet region.
A method for forming an initial crack in a brittle material. In claim 1,
The pulsed laser is an excimer laser;
A method for forming an initial crack in a brittle material.

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