KR101440481B1 - Method for scribing brittle material substrate and device for scribing brittle material substrate - Google Patents

Abstract

[PROBLEM TO BE SOLVED] [Disclosure] [Technical Problem] It is possible to easily carry out division along a curved line to be divided in a curved shape, and to make the edge width small.
[MEANS FOR SOLVING PROBLEMS] This scribing method is a method for forming a scribe groove along a line to be divided of a glass substrate, and includes a heating / cooling step and a scanning step. In the heating and cooling process, the glass substrate is irradiated with a laser beam of a wavelength having absorbency and permeability so as to be focused in the vicinity of the surface (front surface) of the substrate, The cooling medium is sprayed. In the scanning step, a laser spot by laser irradiation and a cooling spot by injection of the cooling medium are scanned along the line to be divided.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a scribing method for a brittle material substrate and a scribing apparatus for a brittle material substrate,

The present invention relates to a scribing method for a brittle material substrate, and more particularly to a scribing method for forming a scribe groove along a line to be divided of a brittle material substrate.

As a method of forming a scribe groove for dividing on a glass substrate, there is a method of forming using a laser beam. In this case, a scribe groove is formed by irradiating a laser beam along the line along which the material is to be divided and dissolving and evaporating a part of the substrate. In this method, however, a part of the dissolved and vaporized substrate adheres to the surface (surface) of the substrate, which may lead to deterioration in quality. In addition, the flaws formed in the melted and evaporated portions cause a decrease in the strength of the cross-section of the substrate.

Therefore, as a method of separating another glass substrate, a processing method using a CO ₂ laser which is absorbed on a glass substrate surface is provided. Here, the surface of the substrate is heated by irradiating and scanning a laser on the glass substrate. Then, this heating region is cooled by a cooling medium injected from a cooling nozzle to advance cracks. Thus, the scribe groove is formed along the line along which the substrate is to be divided, and the glass substrate is divided.

However, in such a method, since the shape of the laser beam is elliptical, it is difficult to form or divide the scribe grooves along curved line segments to be divided. In addition, since there are optimum processing conditions depending on the length or width of the beam, it is necessary to find such processing conditions. Furthermore, since a beam having a width of several millimeters is usually required under a condition of a practical processing speed of at least several mm / s, there is a limit to the distance from the substrate (hereinafter referred to as "edge width" have. That is, when the width of the edge is extremely small and becomes less than the width of the beam, it becomes impossible to divide the line along the line to be divided.

In addition, in Patent Document 1, when the glass substrate or the like is divided along a line to be divided on a curve, the strength of both ends of a linear beam spot having a predetermined length is remarkably increased, Is moved so that both ends thereof are located on the line to be divided, and processing is performed.

Japanese Patent Publication No. 2003-516236

In the processing method shown in Patent Document 1, it is necessary to scan both ends of a linear beam spot along a line to be divided. In order to perform such scanning, it is necessary to perform very complicated control. Further, the shape of the curved segment is also limited, for example, it can not be divided along a curve having a small curvature. In addition, since the beam width can not be reduced, the problem that the width of the processable edge is limited can not be solved.

An object of the present invention is to provide a scribe method capable of easily dividing along a line to be divided on a curve and reducing the edge width.

A scribing method of a brittle material substrate according to the first invention is a method of forming a scribe groove along a line to be divided of a brittle material substrate, and includes the following steps.

Heating and cooling process: A laser beam of a wavelength having absorbency and transparency to the brittle material substrate is condensed and focused so that the focal point is located within the range from the front surface to the back surface of the brittle material substrate, The cooling medium is jetted simultaneously with laser irradiation.

Injection process: The beam spot by laser irradiation and the cooling spot by injection of cooling medium are scanned along the line to be divided.
The scribing method of the brittle material substrate according to the first invention is characterized in that the surface to which the laser is irradiated and the surface to which the cooling medium is sprayed are the same as the surface of the brittle material substrate.

Here, the substrate is irradiated with a laser having a certain degree of transparency and absorbency with respect to the substrate. By this laser irradiation, the substrate is heated to the inside as well as the surface. Simultaneously with this heating, the heated portion is cooled by the cooling medium. For this reason, a temperature gradient occurs inside the substrate. Due to this temperature gradient, a tensile stress is generated on the substrate surface, and a compressive stress is generated in the substrate. Thereby, the substrate is cracked. Then, by scanning the above-mentioned beam spot and cooling spots along the line along which the material is to be divided, the crack progresses along the line along which the material is to be divided, and a scribe groove is formed.

In this method, since the focal point of the laser is condensed so as to be positioned between the substrate surface and the back surface, that is, in the vicinity of the surface, and the cooling spot is formed simultaneously with the laser irradiation at the laser irradiation position, Can be scribed. Further, since there is little time difference from the heating by the laser irradiation to the cooling by the cooling medium, the spread of the temperature to the surroundings becomes small. Therefore, even if the width of the edge is small, asymmetry of the temperature between the end side and the opposite side of the substrate is unlikely to occur. As a result, machining with a small edge width becomes possible as compared with the conventional machining method.

The scribing method of the brittle material substrate according to the second invention is the scribing method of the brittle material substrate according to the first aspect of the present invention wherein the scanning start end (start end) of the line to be divided on the surface of the brittle material substrate, Lt; RTI ID = 0.0 > cracking < / RTI >

Here, an initial crack is formed at the scanning start end of the line to be divided. Thereafter, a heating / cooling process and a scanning process are performed. In this case, the crack progresses from the initial crack along the line to be divided, and a scribe groove is formed.

In the scribing method of the brittle material substrate according to the third invention, in the method according to the first or second invention, the wavelength of the laser in the heating and cooling process is 2.7 탆 or more and 4.0 탆 or less.

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

The scribing method of the brittle material substrate according to the fourth invention is the glass substrate according to the method of the first or second invention.

The scribing method of the brittle material substrate according to the fifth invention is such that in the method according to the first or second invention, the cooling medium is sprayed onto the surface of the substrate such that the injection processing mark by laser irradiation is located at the center of the spraying target.

A scribing method of a brittle material substrate according to a sixth aspect of the present invention is the scribing method of the brittle material substrate according to the first or second aspect of the present invention, And a reflective plate for reflecting light.

As described above, when the thickness of the substrate is thin, even if the laser is irradiated, the substrate can not sufficiently absorb the laser, and the heating becomes insufficient. Thus, in the sixth invention, a reflecting plate for reflecting the laser is provided on the surface opposite to the laser irradiation side of the substrate. By carrying out this process, even a thin substrate can sufficiently absorb the laser, and the inside of the substrate can be sufficiently heated.

A scribing apparatus for a brittle material substrate according to the seventh invention is an apparatus for forming a scribe groove along a line to be divided of a brittle material substrate and includes a table, a laser oscillator, an optical system, a condenser lens, a cooling nozzle and a moving mechanism . The table is mounted with a brittle material substrate as an object to be processed. The laser oscillator outputs a laser having a wavelength that is absorbable and permeable to the brittle material substrate. The optical system guides the laser from the laser oscillator to the table. The condensing lens condenses the laser such that the focus of the laser led to the table is located between the surface and the back of the brittle material substrate. The cooling nozzle forms a cooling spot by jetting a coolant onto the laser irradiation area of the brittle material substrate simultaneously with laser irradiation. The moving mechanism relatively moves the irradiation area of the laser and the cooling spot in the horizontal plane with respect to the brittle material substrate. Further, the surface to which the laser is irradiated and the surface to which the cooling medium is sprayed are the same as the surface of the brittle material substrate.

The scribing device for a brittle material substrate according to an eighth aspect of the present invention is the device according to the seventh aspect further comprising a lens moving mechanism for moving the focusing lens up and down.

The scribing device for a brittle material substrate according to the ninth invention is the device according to the seventh or eighth invention, wherein an initial crack forming means Respectively.

As described above, according to the present invention, it is possible to easily perform the division along the line to be divided on the curve, and further, the width of the edge can be reduced.

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a schematic block diagram of an apparatus for carrying out a scribing method according to an embodiment of the present invention; FIG.
2A shows the transmittance of soda glass with respect to laser wavelength;
Fig. 2B is a diagram showing the substrate transmittance and the absorptivity of the laser for each sheet thickness. Fig.
3 is a photograph showing a laser irradiation area (irradiation station) and a cooling spot (injection station).
4 is a view for explaining a relationship between a focal point position (substrate surface, inside, and back side) of a laser and a scribe margin.
5 is a view for explaining a relationship between a focal position of a laser (substrate above) and a scribe margin.
Fig. 6 is a diagram showing an amount of deviation from a line scheduled to be divided in the case where a line is divided along a line to be divided on a straight line in a processing method according to an embodiment of the present invention; Fig.
7 is a diagram showing an amount of deviation from a line scheduled to be divided in the case where a work is machined along a line to be divided on a curve in a machining method according to an embodiment of the present invention.

[Device Configuration]

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a diagram showing a schematic configuration of a scribe apparatus for carrying out a method according to an embodiment of the present invention; FIG. The scribe device 1 is, for example, a device for dividing a single mother substrate into a plurality of glass substrates. Here, the glass substrate is, for example, a soda glass substrate.

The scribing apparatus 1 includes a table 2 on which a glass substrate G as an object to be processed is placed, a laser oscillator 3, a reflection mirror (not shown) for guiding the laser from the laser oscillator 3 to the table 2 4, a condenser lens 5, and a cooling nozzle 6.

Here, the laser oscillator 3 outputs a laser beam having a wavelength that is absorbable and permeable to the glass substrate G. The condenser lens 5 condenses the laser so that the focal point is located between the surface of the glass substrate G and the back surface. The cooling nozzle 6 forms a cooling spot by spraying a coolant supplied from a coolant source (not shown) onto the surface of the glass substrate G. [

The scribing apparatus 1 is provided with a table moving mechanism 10 for moving the table 2 on which the glass substrate G is placed in a horizontal plane and a lens moving mechanism for moving the collecting lens 5 up and down 11 are provided. By the table moving mechanism 10, the irradiation area of the laser (beam spot) and the cooling spot are scanned along the line to be divided.

Further, in this scribing apparatus 1, an initial crack forming means 12 for forming an initial crack to be a starting point of scribing is provided at an end of the glass substrate G on the scanning start side. As the initial crack forming means 12, a mechanical tool such as an indenter or a cutter wheel is used, but it is also possible to form an initial crack by laser ablation.

[How to scribe]

An initial crack is formed at the end of the glass substrate G on the scanning start side of the line to be divided of the glass substrate G serving as a starting point of the scribe by using the initial crack forming means such as a cutter wheel or the like.

Next, the glass substrate G is irradiated with a laser. The laser is condensed by the condenser lens 5 such that the focal point is located on the surface of the glass substrate G or between the surface and the back surface. Further, the cooling medium is jetted from the cooling nozzle 6 to the laser-irradiated area simultaneously with the irradiation of the laser.

Here, since the laser beam is absorbed and permeable to the glass substrate G as a laser, the surface and the interior of the glass substrate G are heated by laser irradiation. On the other hand, the cooling medium is injected into the laser irradiation region to be cooled. As a result, a temperature gradient occurs inside the substrate, tensile stress is generated on the surface of the glass substrate G, and compressive stress is generated inside. Thereby, the substrate is cracked.

By scanning the above laser spots and cooling spots along the line along which the material is to be divided, cracks are developed along the line along which the material is to be divided, and scribe grooves are formed.

- Example -

<Laser>

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

As apparent from these figures, in the glass substrate having the thickness of 1.3 mm (solid line) and 1.8 mm (broken line) in the wavelength range of 2.8 탆 to 4.0 탆, the transmittance was 55%, 46% , 54%, and it has some degree of absorbency and permeability. In the substrate having such a thickness, the irradiated laser was absorbed into the substrate, and scribing was possible.

Incidentally, even if the absorptivity is low due to the thinness of the plate thickness or the like, if the absorptivity is 10% or more, a higher output laser may be used, or a reflector may be provided on the surface opposite to the surface irradiated with the laser The laser can be sufficiently absorbed inside the substrate. Further, by performing cooling from the surface opposite to the laser irradiation surface, a sufficient temperature gradient can be given to the inside of the substrate for crack propagation.

Incidentally, in the following experiment, an Er fiber laser having a wavelength of 2.8 mu m is used.

<Beam spot and cooling spot>

Fig. 3 is a photograph showing an enlarged view of the details of the machining portion. In Fig. 3, the portion indicated by the circle L in the center portion is the irradiating station of the laser, and the portion indicated by the circle C is the jetting target of the cooling medium. As is apparent from Fig. 3, laser irradiation and injection of the cooling medium are simultaneously performed so that the beam spot is located at the center of the cooling spot.

<Effect of focus position>

4, the focal position of the laser is set as the substrate surface (a), the substrate center (b), and the back surface (c) of the substrate. The laser output and the scanning speed are variously changed to determine whether scribing is possible, It shows the experimental results of how the margin changes. In addition, the glass substrate used in this experiment was soda glass having a thickness of 1.3 mm.

In Fig. 4, &quot;? &Quot; indicates that scribing is possible (cracks propagated along the line along which the substrate is divided from the initial cracks) (The crack along the line along which the material is to be divided advances from the initial crack, but the progress of the crack stops during processing), and the front represents the front diameter (the crack that does not follow the line to be divided is advanced).

It can be seen from Fig. 4 that even if the focal position is changed between the substrate surface and the back surface, the scribe margins are almost the same.

On the other hand, FIG. 5 shows the results of an experiment in which the same glass substrates as in FIG. 4 were processed with their focal positions spaced upward (upward) by 10 mm from the upper surface (upper surface) of the glass substrate. In this case, the beam diameter on the surface of the glass substrate is 660 占 퐉. Therefore, the beam power density on the substrate surface is low, and the substrate temperature is not sufficiently raised. Therefore, scribing can not be performed unless the scanning speed is made slow and the laser output is made high.

From the above experimental results, it is understood that it is preferable to set the focal position of the laser between the front surface of the glass substrate and the back surface to perform the processing.

<Deviation from line to be divided>

Fig. 6 is an experimental example showing how the cracks are formed to some extent from the line to be divided in the case where the processing method of the present embodiment is carried out. The horizontal axis represents the position along the division line (0 mm represents the base judgment of the initial crack side (substrate edge)), and the vertical axis represents the amount of deviation from the line to be divided. In addition, the glass substrate used in the experiment was a soda glass having a thickness of 1.3 mm and a length of 55 mm. The laser output was 7.5 W and the scanning speed was 20 mm / s.

As shown in Fig. 6, the amount of deviation from the line to be divided is +7 占 퐉 to -10 占 퐉, and it can be seen that there is no great deviation even by the processing method of this embodiment.

Incidentally, when the processing method of the present embodiment was performed along the curved dividing line SL on the curve as shown in Fig. 7, the scribe grooves formed had a deviation amount of 20 mu m at the maximum. However, since there is a tendency to deviate to one side (one side) of the line SS to be divided, it is possible to perform machining in anticipation of this deviation.

[Characteristic]

(1) Since the focal point of the laser is set near the substrate surface and the cooling spot is formed simultaneously with the laser irradiation at the laser irradiation position, the substrate can be easily scribed along the line to be divided on the curve.

(2) Since the heating and cooling are performed simultaneously in the same region of the substrate, the spread of the temperature around the substrate is reduced. Therefore, even if the width of the edge is small, asymmetry of the temperature between the end side and the opposite side of the substrate is unlikely to occur. As a result, machining with a small edge width becomes possible as compared with the conventional machining method.

(3) By using a laser having a wavelength of 2.8 탆 or more and 4.0 탆 or less with respect to a glass substrate, it is possible to effectively heat the substrate from the surface to the inside thereof. Therefore, the crack smoothly advances, and deviation from the line to be divided is suppressed.

(4) In a glass substrate having a plate thickness of 1.0 mm or more and 2.0 mm or less, by using a laser having a wavelength of 2.8 탆 or more and 4.0 m or less, it is possible to sufficiently heat the inside of the substrate and form a good scribe groove.

[Other Embodiments]

The present invention is not limited to the embodiments described above, and various modifications or alterations are possible without departing from the scope of the present invention.

For example, in the above embodiment, experimental examples are shown using soda glass as a brittle material substrate, but the brittle material substrate is not limited to soda glass.

2: Table
3: Laser oscillator
5: condenser lens
6: Cooling nozzle

Claims (9)

A scribing method of a brittle material substrate for forming a scribe groove along a line to be divided of a brittle material substrate,
The laser beam having a wavelength that is absorbent and permeable to the brittle material substrate is condensed and focused so that the focal point is positioned within the range from the front surface (front surface) to the back surface (rear surface) of the brittle material substrate, A heating and cooling step of jetting a cooling medium simultaneously with laser irradiation,
A scanning step of scanning the cooling spot by the beam irradiation by the laser irradiation and the cooling medium by the injection of the cooling medium along the line to be divided
/ RTI &gt;
Characterized in that the surface to which the laser is irradiated and the surface to which the cooling medium is injected are the same as the surface of the brittle material substrate.
Method of scribing a brittle material substrate. The method according to claim 1,
Further comprising an initial crack forming step of forming an initial crack at a scanning start end (starting end) of a line to be divided on the surface of the brittle material substrate as a previous step of the heating and cooling step Scribe method. 3. The method according to claim 1 or 2,
Wherein the wavelength of the laser in the heating and cooling step is 2.7 占 퐉 or more and 4.0 占 퐉 or less. 3. The method according to claim 1 or 2,
Wherein the brittle material substrate is a glass substrate. 3. The method according to claim 1 or 2,
Wherein the cooling medium is sprayed onto the surface of the substrate such that the spraying traces by laser irradiation are located at the center of the spraying station. 3. The method according to claim 1 or 2,
Further comprising a preparing step of providing a reflecting plate for reflecting the laser on the surface opposite to the surface on the laser irradiation side of the brittle material substrate as a previous step of the heating and cooling step. A scribe device for a brittle material substrate which forms a scribe groove along a line to be divided of a brittle material substrate,
A table on which a brittle material substrate as an object to be processed is placed,
A laser oscillator for outputting a laser having a wavelength that is absorbent and permeable to the brittle material substrate;
An optical system for guiding the laser from the laser oscillator to the table,
A condensing lens for condensing the laser so that the focus of the laser led to the table is located between the surface and the back of the brittle material substrate;
A cooling nozzle for jetting a coolant to the laser irradiation area of the brittle material substrate simultaneously with laser irradiation to form a cooling spot;
A moving mechanism for relatively moving the irradiated region of the laser and the cooling spot relative to the brittle material substrate in a horizontal plane,
And,
Characterized in that the surface to which the laser is irradiated and the surface to which the cooling medium is injected are the same as the surface of the brittle material substrate.
A scribing device for a brittle material substrate. 8. The method of claim 7,
And a lens moving mechanism for moving the condensing lens vertically. 9. The method according to claim 7 or 8,
Further comprising an initial crack forming means for forming an initial crack at a scribe starting point on a part of the brittle material substrate.

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