TWI488703B - Scribing method and scribing apparatus for substrate of brittle material - Google Patents

Description

Cutting method and cutting device for brittle material substrate

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a method of dicing a substrate of a brittle material, and more particularly to a method of forming a dicing trench along a line of cutting of a substrate of a brittle material.

A method of forming a dicing groove for cutting into a glass substrate is a method of forming using laser light. In this case, the laser light is irradiated along the line to cut so that a part of the substrate is dissolved and evaporated, thereby forming a dicing groove. However, in this method, a part of the substrate which is dissolved and evaporated adheres to the surface of the substrate, which is accompanied by deterioration of quality. Furthermore, the flaw formed in the dissolved and evaporated portion causes a decrease in the strength of the end face of the substrate.

Therefore, as for the other glass substrate cutting method, there is provided a processing method using a CO ₂ laser which is absorbed on the surface of the glass substrate. In this method, the surface of the substrate is heated by irradiating a laser onto a glass substrate and scanning. Then, the heating region is cooled by a cooling medium ejected from a cooling nozzle to expand the crack. Thereby, a dicing groove is formed along the line to be cut and the glass substrate is cut.

However, in this method, since the shape of the laser beam is elliptical, it is difficult to form a cutting groove along the curved planned cutting line, or to perform cutting. Furthermore, since there are optimum processing conditions depending on the length and width of the laser, it is necessary to find the processing conditions. Further, in the practical processing speed condition of at least several mm/s, since a beam having a width of several mm is usually required, the distance from the substrate to the cutting line (hereinafter, referred to as "the flange width") There will be restrictions. That is, when the flange width is extremely small and becomes below the width of the beam, it is impossible to cut along such a planned cutting line.

Further, Patent Document 1 discloses that when the glass substrate or the like is cut along a curved planned cutting line, the strength of both ends of a linear beam spot having a predetermined length is significantly increased. And moving the both ends to be processed on the cutting line.

(previous technical literature) (Patent Literature)

Patent Document 1: Japanese Patent Publication No. 2003-516236

In the processing method disclosed in Patent Document 1, it is necessary to scan both ends of a linear beam spot along a line to be cut. In order to perform such a scan, very complicated control must be performed. Furthermore, the shape of the curve capable of cutting is also limited, for example, it is not possible to cut along a curve having a small curvature. Further, since the beam width cannot be reduced, the problem of limitation in the flange width that can be processed cannot be solved.

The object of the present invention is to provide a cutting method capable of following a curve The cut is easily cut by the predetermined line, and the flange width can be reduced.

The method of cutting a brittle material substrate according to the first aspect of the invention is a method of forming a dicing groove along a line to be cut of a brittle material substrate, and includes the following steps.

Heating/cooling step: focusing and illuminating a laser having a wavelength of absorption and penetration with respect to a brittle material substrate in such a manner that the focus is in a range from the surface of the substrate to the back surface, and in the laser The irradiation area is irradiated with the cooling medium while performing laser irradiation.

Scanning step: scanning the laser irradiation spot of the laser beam and the cooling point of the cooling medium along the line to be cut.

Here, a laser having a certain degree of transparency and absorption with respect to the substrate is irradiated onto the substrate. By the irradiation of the laser, the substrate is heated not only from the surface but also from the inside. Further, at the same time as the heating, the heated portion is cooled by the cooling medium. Therefore, a temperature gradient is generated inside the substrate. Due to this temperature gradient, tensile stress is generated on the surface of the substrate, and compressive stress is generated inside the substrate. Therefore, the substrate is cracked. Further, by scanning the above beam spot and the cooling point along the line to be cut, the crack spreads along the line to be cut to form a cutting groove.

In this method, since the focus of the laser is concentrated between the surface of the substrate and the back surface, that is, the light is collected in the vicinity of the surface, and the cooling point is formed while the laser is irradiated to the laser irradiation position, The substrate is easily cut along a curved cut line. Further, since there is almost no time difference from the heating of the laser irradiation to the cooling of the cooling medium, the temperature diffusion to the surroundings is reduced. Therefore, even in the case where the flange width is small At the same time, it is not easy to cause temperature asymmetry between the end side and the opposite side of the substrate. As a result, it is possible to perform processing with a small flange width as compared with the conventional processing method.

According to a second aspect of the invention, in the method of the first aspect of the invention, the initial crack forming step of forming an initial crack at the scanning start end of the planned cutting line on the surface of the brittle material substrate is used as heating/ The steps before the cooling step.

Here, an initial crack is formed at the scanning start end of the cut line. Thereafter, the heating/cooling step and the scanning step are performed. At this time, the crack will expand from the initial crack along the planned cutting line to form a cutting groove.

The method of cutting a brittle material substrate according to the third aspect of the invention is the method according to the first or second aspect of the invention, wherein the wavelength of the laser in the heating/cooling step is 2.7 μm or more and 4.0 μm or less.

By irradiating, for example, a glass substrate using such a laser, it is possible to heat the inside not only on the surface of the substrate but also on the surface of the substrate.

A method of cutting a brittle material substrate according to a fourth aspect of the invention is the method of any one of the first to third aspects, wherein the brittle material substrate is a glass substrate.

In the method of cutting a brittle material substrate according to the fifth aspect of the invention, the cooling medium is sprayed onto the surface of the substrate such that the jet processing mark of the laser irradiation is located at the center of the ejection mark.

The cutting method of the brittle material substrate according to the sixth aspect of the invention is the method of any one of the first to fifth invention, further comprising the step of preparing a reflecting plate for reflecting the laser on the back surface of the brittle material substrate as heating/cooling Steps before the steps.

As described above, when the thickness of the substrate is thin, even if the laser is irradiated, the substrate cannot sufficiently absorb the laser, and the heating is insufficient. Therefore, in the fifth aspect of the invention, a reflecting plate for reflecting a laser is provided on a surface of the substrate opposite to the surface on which the laser side is irradiated. By performing this step, even if it is a thin substrate, the laser can be sufficiently absorbed, and the inside of the substrate can be sufficiently heated.

A cutting device for a brittle material substrate according to a seventh aspect of the present invention is a device for forming a dicing groove along a line to be cut of a brittle material substrate, comprising: a table; a laser oscillator; an optical system; a condensing lens (lens) ; cooling nozzle; and moving mechanism. The table is placed as a substrate for a brittle material to be processed. A laser oscillator outputs a laser having a wavelength that is absorptive and penetrable with respect to a brittle material substrate. The optical system directs the laser light from the laser oscillator to the table. The concentrating lens condenses the laser light so that the focus of the laser light guided to the table is in the range from the surface to the back surface of the brittle material substrate. The cooling nozzle forms a cooling point by injecting a refrigerant to a laser irradiation region of the brittle material substrate while performing laser irradiation. The moving mechanism relatively moves the irradiation region and the cooling point of the laser light in the horizontal plane with respect to the brittle material substrate.

A cutting device for a brittle material substrate according to a seventh aspect of the invention is the device of the seventh aspect of the invention, further comprising a lens moving mechanism for moving the condensing lens up and down.

A cutting device for a brittle material substrate according to a ninth aspect of the invention is the device according to the seventh or eighth aspect of the present invention, which comprises an initial crack forming means for forming an initial crack as a cutting starting point in a portion of the brittle material substrate.

As described above, the present invention can easily perform cutting along a curved cutting line and can reduce the flange width.

1‧‧‧ cutting device

2‧‧‧Workbench

3‧‧‧Laser oscillator

4‧‧‧Mirror

5‧‧‧ Concentrating lens

6‧‧‧Cooling nozzle

10‧‧‧Workbench moving mechanism

11‧‧‧Lens moving mechanism

12‧‧‧Initial crack formation

G‧‧‧glass substrate

Fig. 1 is a schematic configuration diagram of an apparatus for carrying out a cutting method according to an embodiment of the present invention.

Figure 2A is a graph showing the transmittance of soda-lime glass relative to the laser wavelength.

Figure 2B is a graph showing substrate penetration and absorption for each plate thickness of the laser.

Fig. 3 is a photograph showing a laser irradiation area (irradiation mark) and a cooling point (spray mark).

Fig. 4 (a) to (c) are diagrams for explaining the relationship between the focus position of the laser (substrate surface, inside, and back surface) and the cutting edge.

Figure 5 is a diagram for explaining the relationship between the focus position of the laser (above the substrate) and the cutting edge.

Fig. 6 is a view showing the amount of shift from the planned cutting line when the processing method according to the embodiment of the present invention is processed along a linear cutting line.

Fig. 7 is a view showing the amount of shift from the planned cutting line when the machining method according to the embodiment of the present invention is processed along a curved cutting line.

[Device configuration]

Figure 1 is a diagram showing the method for carrying out an embodiment of the present invention. A schematic diagram of the cutting device. The cutting device 1 is, for example, a device for dividing a mother substrate into a plurality of glass substrates. Among them, the glass substrate is, for example, a soda lime glass substrate.

The cutting device 1 includes: a table 2 on which a glass substrate G to be processed is placed; a laser oscillator 3; and a mirror 4 for guiding the laser from the laser oscillator 3 to the table 2 side; a condenser lens 5; and a cooling nozzle 6.

Among them, the laser oscillator 3 outputs a laser having a wavelength of absorption and penetration with respect to the glass substrate G. The condensing lens 5 condenses the laser light so that the focus is located between the surface of the glass substrate G and the back surface. The cooling nozzle 6 sprays a refrigerant supplied from a refrigerant source (not shown) onto the surface of the glass substrate G to form a cooling point.

Further, the cutting device 1 is provided with a table moving mechanism 10 that moves a table 2 on which a glass substrate G is placed in a horizontal plane, and a lens moving mechanism 11 that moves the collecting lens 5 up and down. By the table moving mechanism 10, the irradiation area (beam spot) of the laser and the cooling point are scanned along the line to cut.

In addition, the cutting device 1 is provided with an initial crack forming means 12 for forming an initial crack belonging to the cutting start point at the end portion on the scanning start side of the glass substrate G. In the initial crack forming means 12, a mechanical tool such as an indenter or a cutter wheel is used, but initial cracking can be formed by laser ablation processing.

[Cutting method]

First, using a primary crack forming means such as a cutter wheel on a glass substrate The end portion on the scanning start side of the cutting planned line of G forms an initial crack belonging to the cutting start point.

Next, the glass substrate G is irradiated with a laser. The laser is condensed by the condensing lens 5 so that the focus is on the surface of the glass substrate G or between the surface and the back surface. Further, while the laser irradiation is being performed, the cooling nozzle 6 ejects the cooling medium to the area irradiated by the laser.

In the laser, since the laser having a wavelength of absorption and penetration with respect to the glass substrate G is used, the surface and the inside of the glass substrate G are heated by laser irradiation. On the other hand, the cooling medium is sprayed on the laser irradiation area to cool it. Therefore, a temperature gradient is generated inside the substrate, and tensile stress is generated on the surface of the substrate G, and a compressive stress is generated inside. Thereby, cracks are generated in the substrate.

By scanning the above laser spot and cooling point along the line to be cut, the crack system spreads along the line to be cut to form a cutting groove.

(Example) <Laser>

Fig. 2A shows the relationship between the wavelength and the transmittance of a laser (Er fiber laser) having a soda lime glass having various thicknesses. Furthermore, Figure 2B shows the penetration and absorption rate for each plate thickness. In addition, the absorption rate is a calculated value.

As is apparent from the figures, the transmittances of the glass substrates having a thickness of 1.3 mm (solid line) and 1.8 mm (dashed line) in the range of 2.8 μm to 4.0 μm, respectively, are 55%, 46, respectively. %, the absorption rate is 45%, 54%, respectively, and has a certain degree of absorption and penetration. Substrates of the thickness The laser beam that is irradiated absorbs the inside of the substrate and can be cut.

Further, even when the absorption rate is low due to reasons such as a thin plate thickness, if the absorption rate is 10% or more, a laser having a higher output or a side opposite to the surface irradiated by the laser can be used. The reflector is provided to reflect the laser, so that the laser is sufficiently absorbed inside the substrate. Further, by cooling from the surface opposite to the laser irradiation surface, a sufficient temperature gradient required for crack propagation can be imparted to the inside of the substrate.

In addition, in the following experiments, an Er fiber laser having a wavelength of 2.8 μm was used.

<beam point and cooling point>

Fig. 3 is a photograph showing an enlarged display of the detailed state of the processed portion. In Fig. 3, the portion indicated by the circle L of the center portion is the irradiation mark of the laser, and the portion indicated by the circle C is the ejection mark of the cooling medium. As is apparent from Fig. 3, the laser irradiation and the ejection of the cooling medium are simultaneously performed so that the beam spot is located at the center of the cooling point.

<Impact of focus position>

Figure 4 shows the focus position of the laser as the substrate surface (a), the substrate center (b), the substrate back surface (c), and various changes to the laser output and scanning speed, and whether the experiment can be cut, That is, the result of the experimental cutting edge depending on how the focus position changes. In addition, the glass substrate used in this experiment was a 1.3 mm soda lime glass substrate.

In Fig. 4, "○" shows that cutting is possible (the crack spreads from the initial crack along the planned cutting line), and the "×" shows that the cutting is impossible (the crack along the planned cutting line does not start from the initial The crack begins to expand) The processing stops (the crack along the planned cutting line expands from the initial crack, but the expansion of the crack stops during the processing), the "first" shows the expansion first (the crack does not expand along the cutting line) ).

As can be seen from Fig. 4, even if the focus position is changed between the surface of the substrate and the back surface, the divided edges are substantially the same.

On the other hand, Fig. 5 is an experimental result of processing the glass substrate which is the same as that of Fig. 4 by leaving the focus position upward from the upper surface of the glass substrate up to 10 mm. In this case, the beam diameter of the surface of the glass substrate was 660 μm. Therefore, the beam power density of the substrate surface is low, and the substrate temperature is not sufficiently increased. Therefore, if the scanning speed is slowed and the laser output is not increased, the cutting cannot be performed.

According to the above experimental results, it is preferable to set the focus position of the laser from the surface of the substrate to the back surface for processing.

<offset from the cut line to be cut>

Fig. 6 is a view showing an experimental example in which the crack is formed by the degree of deviation of the planned cutting line when the processing method of the present embodiment is carried out. The horizontal axis shows the position along the cutting line (0 mm indicates the substrate end on the initial crack side), and the vertical axis shows the offset from the planned cutting line. Further, the glass substrate used in the experiment was a soda lime glass substrate having a thickness of 1.3 mm and a length of 55 mm. Furthermore, the laser output is 7.5W and the scanning speed is 20mm/s.

As shown in Fig. 6, the offset from the planned cutting line is between +7 μm and -10 μm, and it is understood that the processing method according to the present embodiment does not have a large offset.

In addition, in the curved dividing line SL along the curved line shown in FIG. When the processing method of the present embodiment is carried out, the formed dicing groove is offset by a maximum of 20 μm. However, since there is a tendency to shift to one side of the division planned line SL, the offset can be expected to be processed.

[feature]

(1) Since the focus of the laser is set near the surface of the substrate, and the cooling point is formed at the laser irradiation position while performing the laser irradiation, the substrate can be easily cut along the curved cutting line. .

(2) Since heating and cooling are simultaneously performed on the same region of the substrate, the temperature diffusion to the surroundings is reduced. Therefore, even in the case where the flange width is small, the asymmetry of the temperature between the end side and the other side of the substrate is not easily generated. As a result, it is possible to perform processing with a small flange width as compared with the conventional processing method.

(3) By using a laser having a wavelength of 2.8 μm or more and 4.0 μm or less for the glass substrate, heating can be efficiently performed from the surface of the substrate to the inside. Therefore, the crack spreads smoothly, and the offset from the planned cutting line can be suppressed.

(4) In the case of a glass substrate having a thickness of 1.0 mm or more and 2.0 mm or less, by using a laser having a wavelength of 2.8 μm or more and 4.0 μm or less, the substrate can be sufficiently heated to the inside of the substrate, and can be formed well. Cutting groove.

[Other Embodiments]

The present invention is not limited to the above embodiments, and various modifications and changes can be made without departing from the scope of the invention.

For example, in the above embodiment, an experimental example using soda lime glass as a brittle material substrate is shown, but the brittle material substrate is not limited. Set in soda lime glass.

1‧‧‧ cutting device

2‧‧‧Workbench

3‧‧‧Laser oscillator

4‧‧‧Mirror

5‧‧‧ Concentrating lens

6‧‧‧Cooling nozzle

10‧‧‧Workbench moving mechanism

11‧‧‧Lens moving mechanism

12‧‧‧Initial crack formation

G‧‧‧glass substrate

Claims (9)

A method for cutting a substrate of a brittle material, which is formed by cutting a predetermined line along a line of cutting of a brittle material substrate, comprising the steps of: heating/cooling step so that the focus is in a range from the surface to the back of the substrate; a method of concentrating and irradiating a laser having a wavelength of absorption and penetration with respect to the brittle material substrate, and spraying a cooling medium while performing laser irradiation on the laser irradiation region; and a scanning step The laser beam of the aforementioned laser irradiation and the cooling point of the cooling medium are scanned along the aforementioned cutting line. The method for cutting a brittle material substrate according to claim 1, further comprising: an initial crack forming step as a pre-step of the heating/cooling step, scanning a predetermined line of the surface of the brittle material substrate The initial crack is formed at the beginning. The method of cutting a brittle material substrate according to the first or second aspect of the invention, wherein the wavelength of the laser in the heating/cooling step is 2.7 μm or more and 4.0 μm or less. The method of cutting a brittle material substrate according to claim 1, wherein the brittle material substrate is a glass substrate. The method of cutting a brittle material substrate according to the first aspect of the invention, wherein the cooling medium is sprayed onto the surface of the substrate such that the jet processing mark of the laser irradiation is located at a center of the ejection mark. The cutting side of the brittle material substrate as described in claim 1 of the patent application scope The method includes a step of preparing a step before the heating/cooling step, and providing a reflecting plate for reflecting the laser on a surface of the brittle material substrate opposite to the surface on the laser irradiation side. A cutting device for a brittle material substrate, which is formed by cutting a predetermined line along a cutting line of a brittle material substrate, comprising: a working table on which a brittle material substrate as a processing object is placed; and a laser oscillator outputting relative to the foregoing a brittle material substrate having a laser having an absorptive and penetrating wavelength; an optical system for directing laser light from the laser oscillator to the aforementioned stage; and a collecting lens for directing the laser light to the aforementioned table The focus is on the surface of the brittle material substrate between the surface and the back surface to condense the laser; the cooling nozzle is sprayed with a refrigerant to the laser irradiation region of the brittle material substrate to form a cooling point while performing laser irradiation; And a moving mechanism for relatively moving the irradiation region and the cooling point of the laser light in a horizontal plane with respect to the brittle material substrate. The cutting device for a brittle material substrate according to claim 7, further comprising: a lens moving mechanism for moving the condensing lens up and down. The cutting device for a brittle material substrate according to claim 7 or 8, further comprising: an initial crack forming means for A part of the aforementioned brittle material substrate forms an initial crack as a starting point of cutting.