JP2022026724A - Scribe line formation method, dividing method of brittle substrate, scribe line formation device, and small substrate - Google Patents

Abstract

To form a scribe line capable of cutting out easily a high quality substrate by irradiating a laser beam along a processing line for forming a scribe line.SOLUTION: A scribe line formation method includes a step for irradiating a substrate S at a prescribed irradiation interval in each prescribed irradiation cycle, with a processing laser beam L1 having a prescribed beam diameter, along a processing line for forming the scribe line on the substrate S. The irradiation interval (X(μm)) and the irradiation cycle (Y(μs)) of the processing laser beam L1 satisfy a condition Y≥6.0X.SELECTED DRAWING: Figure 6

Description

The present invention relates to a method of irradiating a brittle substrate such as glass with a laser beam to form a scribe line, a method of dividing a brittle substrate, a scrib line forming apparatus for forming a scribe line by irradiation with a laser beam, and a brittle substrate. Regarding the small substrate cut out from.

As a method of forming a scribe line for cutting out a small substrate having an arbitrary shape from a brittle substrate such as glass, a method of scanning a laser beam along a processing line forming the scribe line is known. For example, a method is known in which a pulsed laser beam having a wavelength in the near infrared region is scanned along a processing line on a brittle substrate to form a scribing line along the processing line (for example, a patent). See Document 1).

Japanese Unexamined Patent Publication No. 2018-52770

In the conventional method of forming a scribe line using laser light, the irradiation conditions of the laser light are not optimized, and the quality of the substrate after cutting along the scribe line is not high. Specifically, when the scribe line was formed by the conventional method, large irregularities and voids (holes) were formed in the cross section of the substrate after cutting. In addition, the end face strength of the cut-out substrate was not sufficient, and the cut-out substrate was easily damaged.
Further, when the scribe line is formed by the conventional method, it is not easy to cut out the substrate because it is necessary to apply a force to the substrate when cutting out the substrate along the scribe line.

An object of the present invention is to irradiate a laser beam along a processing line forming a scribe line to form a scribe line that can easily cut out a high-quality substrate.

Hereinafter, a plurality of aspects will be described as means for solving the problem. These aspects can be arbitrarily combined as needed.
The method for forming a scribe line according to a seemingly present invention is a method for forming a scribe line for cutting out a small substrate from a brittle substrate (for example, a brittle substrate having a thickness of 1 mm or less).
In this scrib line forming method, a processed laser beam having a predetermined beam diameter (for example, 0.5 μm or more and 10 μm or less) is predetermined for each predetermined irradiation cycle along the processed line for forming the scrib line on the brittle substrate. The brittle substrate is provided with a step of irradiating the brittle substrate at the irradiation interval of the above, and the irradiation interval (X (μm)) and the irradiation cycle (Y (μs)) of the processed laser light satisfy the condition of Y ≧ 6.0X.

In the above scribe line forming method, when the brittle substrate is irradiated with the processed laser light to form the scribe line, the irradiation interval and the irradiation cycle of the processed laser light satisfying the relationship of Y ≧ 6.0X are selected. There is. As a result, it is possible to form a scribe line that can easily cut out a high-quality small substrate having high strength without forming large irregularities or voids in the cross section cut out from the brittle substrate.

The irradiation interval (X (μm)) and the irradiation cycle (Y (μs)) may satisfy the condition of Y ≧ 6.0X + 2.0. As a result, it is possible to form a scribe line that can easily cut out a high-quality small substrate having high strength without forming large irregularities or voids in the cross section cut out from the brittle substrate.

The irradiation cycle may be in the range of 50 μs or less. As a result, it is possible to easily cut out a high-quality small substrate having high strength without forming large irregularities or voids over the entire cross section.

The irradiation interval may be in the range of 0.1 μm or more. As a result, it is possible to easily cut out a high-quality small substrate having high strength without forming large irregularities or voids over the entire cross section.

The irradiation interval may be in the range of 0.2 μm or more. As a result, it is possible to easily cut out a high-quality small substrate having high strength without forming large irregularities or voids over the entire cross section.

The irradiation interval may be in the range of 0.3 μm or more. As a result, it is possible to easily cut out a high-quality small substrate having high strength without forming large irregularities or voids over the entire cross section.

The irradiation interval may be 0.4 μm or more and 0.6 μm or less in particular. As a result, it is possible to easily cut out a high-quality small substrate having high strength without forming large irregularities or voids over the entire cross section.

The irradiation cycle may be in the range of 1.2 μs or more and 50 μs or less. As a result, it is possible to easily cut out a high-quality small substrate having high strength without forming large irregularities or voids over the entire cross section.

The irradiation cycle may be in the range of 1.8 μs or more and 40 μs or less. As a result, it is possible to easily cut out a high-quality small substrate having high strength without forming large irregularities or voids over the entire cross section.

The irradiation cycle may be particularly in the range of 10 μs or more and 40 μs or less. As a result, it is possible to easily cut out a high-quality small substrate having high strength without forming large irregularities or voids over the entire cross section.

The beam diameter may be in the range of 0.2 μm or more and 10 μm or less. This makes it possible to irradiate an appropriate range of the processing line with the processing laser beam to form an appropriate scribe line.

The degree of overlap of irradiation of the processed laser light may be in the range of 30% or more and 60% or less. As a result, an appropriate scribe line can be formed by avoiding excessive irradiation of the processed laser beam on the same portion of the brittle substrate.

The processed laser light may be a pulsed laser light having a pulse width of 20 picoseconds or less. As a result, the brittle substrate can be appropriately processed by the processing laser light.

In the above scribe line forming method, the step of irradiating the processed laser light may have the following steps.
◎ A step of converting a laser beam output from a laser device at a predetermined irradiation cycle into a ring beam having a constant ring width by an axicon lens.
◎ The step of adjusting the beam diameter of the processed laser light on the brittle substrate by injecting the ring beam into the reduced optical system.
This makes it possible to optimize the processed laser light for forming the scribe line.

The dividing method according to another aspect of the present invention is a method for dividing a brittle substrate for cutting out a small substrate from the brittle substrate. The division method includes the following steps.
◎ A scribe line forming step by the above scribe line forming method.
◎ A division step in which a brittle substrate is divided by applying stress or impact along the scribe line formed in the scribe line forming step to cut out a small substrate.
As a result, a high-quality small substrate having high strength without forming large irregularities or voids in the cross section can be easily cut out from the brittle substrate.

The stress or impact applied in the breaking step may be mechanical stress or impact due to bending, pressing by a break bar roller or the like, or thermal stress or impact due to heating or cooling.

The scribe line forming apparatus according to another aspect of the present invention is an apparatus for forming a scribe line for cutting out a small substrate from a brittle substrate. The scribe line forming apparatus includes a laser system and a drive unit.
The laser system outputs a processed laser beam having a predetermined beam diameter at a predetermined irradiation cycle.
The drive unit moves the brittle substrate with respect to the laser system in order to irradiate the brittle substrate with the processed laser light at predetermined irradiation intervals along the processing line forming the scribe line on the brittle substrate.
When forming a scribe line by the above scribe line forming apparatus, the irradiation interval (X (μm)) and the irradiation cycle (Y (μs)) of the processed laser light satisfy the condition of Y ≧ 6.0X.

In the above scrib line forming apparatus, when the brittle substrate is irradiated with the processed laser light to form the scrib line, the irradiation interval and the irradiation cycle of the processed laser light satisfying the relationship of Y ≧ 6.0X are selected. There is. As a result, it is possible to form a scribe line that can easily cut out a high-quality small substrate having sufficient end face strength without forming large irregularities or voids in the cross section cut out from the brittle substrate.

The laser system of the scribe line forming apparatus may include a laser apparatus, an axicon lens, and a reduction optical system.
The laser device outputs a laser beam at a predetermined irradiation cycle.
The axicon lens converts the laser beam into a ring beam with a constant ring width.
The reduced optical system is an optical system into which a ring beam is incident, and forms a processed laser beam having an adjusted beam diameter on a brittle substrate from the incident ring beam.
This makes it possible to optimize the processed laser light for forming the scribe line.

In the small substrate according to still another aspect of the present invention, a brittle substrate made of glass, quartz, or sapphire is irradiated with a laser beam having a wavelength of 750 nm to 2500 nm to form a scribing line, and the brittle substrate is formed along the brittle line. Obtained by dividing.
This small substrate has a mirror-like cross section having a surface roughness of 0.05 μm or less on at least a part of the cross section, and has an end face strength of 180 MPa or more.

A scrib line can be formed by irradiation with a laser beam, which does not form large irregularities or voids in the cross section cut out from the brittle substrate and can easily cut out a high-quality small substrate having sufficient end face strength.

The schematic diagram of the scribe line forming apparatus of 1st Embodiment of this invention. The figure which shows the structure of the transmission optical system. The flowchart which shows the scribe line formation process by a scribe line forming apparatus. The figure which shows an example of the irradiation state of the processing laser light on the substrate schematically. An optical microscope image of a cross section of a small substrate of Example 1. An optical microscope image of a cross section of a small substrate of Example 2. The figure which shows the result of plotting the relationship between the irradiation interval and irradiation cycle of a processed laser beam, and the formation state of a mirror-like cross section on a graph. An electron microscope image of a small substrate including a mirror-like cross section. Electron micrograph of a small substrate containing a satin-like cross section. The figure which shows an example of the electron microscope image of a void existing in a satin-like cross section. The figure which shows an example of the execution method of a 4-point bending test.

1. 1. First Embodiment (1) Configuration of Scrivener Line Forming Device The overall configuration of the scribe line forming apparatus 100 according to the embodiment of the present invention will be described with reference to FIG. FIG. 1 is a schematic diagram of a scribe line forming apparatus according to the first embodiment of the present invention.
The scribe line forming apparatus 100 is an apparatus for forming a scribe line on a brittle substrate (hereinafter referred to as substrate S) made of glass, quartz, sapphire or the like. The scribe line is formed along a processing line for cutting out a small substrate having an arbitrary shape according to an application or the like from the substrate S. That is, the scribe line is formed to separate the small substrate from the substrate S.
The scribe line forming apparatus 100 includes a laser system 1, a processing table 3, a table drive unit 5, and a control unit 7.

The laser system 1 outputs a laser beam (referred to as a processed laser beam L1) for forming a scribe line on the substrate S. Specifically, the laser system 1 includes a laser device 11, a transmission optical system 13, and a drive mechanism 15.
The laser device 11 outputs the laser beam L2 incident on the transmission optical system 13. The laser device 11 includes a laser oscillator 11a and a laser control unit 11b. The laser oscillator 11a outputs a pulsed laser beam L2 having a wavelength in the infrared region (750 nm to 2500 nm) at a predetermined irradiation cycle. Here, the irradiation cycle is the time from the output of one laser beam pulse to the output of the next laser beam pulse.

The pulse width of the laser beam L2 is set to 100 femtoseconds or more and 20 picoseconds or less in order to appropriately heat the substrate S.

The laser control unit 11b controls the laser oscillator 11a according to the generation conditions of the laser beam L2 (irradiation cycle, intensity of the laser beam L2, etc.).

The transmission optical system 13 incidents the laser beam L2 output from the laser device 11 and outputs the laser beam L2 whose beam diameter is adjusted on the substrate S. Specifically, as shown in FIG. 2, the transmission optical system 13 includes an axicon lens 131 and a reduction optical system 133. FIG. 2 is a diagram showing a configuration of a transmission optical system.

The axicon lens 131 incidents the laser beam L2 and converts the incident laser beam L2 into a ring beam L3 having a constant ring width w in the propagation direction of the laser beam.
The reduction optical system 133 incidents the ring beam L3 and reduces the incident ring beam L3 to form a processed laser beam L1 having an adjusted beam diameter on the substrate S. The reduction optical system 133 is composed of, for example, a plurality of lenses.

Since the transmission optical system 13 has the above configuration, the laser beam L2 output from the laser device 11 can be converted into a processed laser beam L1 that is optimal for forming a scribing line.

In addition to the axicon lens 131 and the reduction optical system 133, the transmission optical system 13 may include other optical members such as a λ / 4 wave plate, a beam expander, and a prism.

The drive mechanism 15 propagates the optical axis direction (propagation of the laser beam L2) of the lenses (axicon lens 131, reduction optical system 133) provided in the transmission optical system 13 in order to adjust the beam diameter of the processed laser beam L1 on the substrate S. Change the position in the direction).

The processing table 3 is a table on which the substrate S is placed. The table drive unit 5 (an example of the drive unit) moves the processing table 3 with respect to the laser system 1 (transmission optical system 13). The table drive unit 5 is a known mechanism having, for example, a guide rail, a motor, and the like.

The control unit 7 has a processor (for example, a CPU), a storage device (for example, ROM, RAM, HDD, SSD, etc.), and various interfaces (for example, an A / D converter, a D / A converter, a communication interface, etc.). It is a computer system. The control unit 7 performs various control operations in the scribe line forming device 100 by executing a program stored in the storage unit (corresponding to a part or all of the storage area of the storage device).
The control unit 7 may be composed of a single processor, or may be composed of a plurality of independent processors for each control.

The control unit 7 outputs, for example, the set value of the output condition of the laser beam L2 to the laser control unit 11b. Further, the control unit 7 adjusts the beam diameter of the processed laser light L1 in the substrate S by controlling the drive mechanism 15.

Further, the control unit 7 moves the processing table 3 in the horizontal direction by controlling the table drive unit 5, and moves the substrate S with respect to the processing laser light L1. That is, the control unit 7 moves the substrate S with respect to the processed laser light L1 and scans the processed laser light L1 on the substrate S. Further, the control unit 7 controls the scanning speed of the processed laser beam L1 on the substrate S by adjusting the moving speed of the processing table 3 in the horizontal direction.

Although not shown, the control unit 7 is connected to a sensor for detecting the size, shape and position of the substrate S, a sensor and a switch for detecting the state of each part of the scribe line forming device 100, and an information input device. There is.

(2) Scrib line forming method and brittle substrate dividing method A scrib line forming method by the scrib line forming apparatus 100 will be described with reference to FIG. FIG. 3 is a flowchart showing a scribe line forming process by the scribe line forming apparatus.
First, in step S1, the substrate S forming the scribe line is placed on the processing table 3.
After that, in step S2, the laser beam L2 is generated from the laser device 11 at a predetermined irradiation cycle, and the processed laser beam L1 having a predetermined beam diameter is emitted from the transmission optical system 13 toward the substrate S. By driving the table drive unit 5 while emitting the processing laser light L1 and moving the processing table 3 in the horizontal direction, the processing laser light L1 is scanned along the processing line for cutting out a small substrate on the substrate S. ..

The beam diameter of the processed laser light L1 on the substrate S is set to a range in which the processed laser light L1 can be irradiated to an appropriate range of the processed line forming the scribe line, for example, 0.2 μm or more and 10 μm. It can be in the following range.

In step S2 described above, the processed laser light L1 is generated at a predetermined irradiation cycle, and the processed laser light L1 is scanned against the substrate S to irradiate the substrate S with a predetermined irradiation as shown in FIG. The processed laser beam L1 is irradiated at the interval D. FIG. 4 is a diagram schematically showing an example of an irradiation state of the processed laser light on the substrate.
The irradiation interval of the processed laser light L1 on the substrate S is determined by the irradiation cycle of the processed laser light L1 and the scanning speed of the processed laser light L1 with respect to the substrate. The irradiation interval D is set to, for example, 0.1 μm or more. The irradiation cycle is set to, for example, 1.2 μs or more.

By irradiating the substrate S with the processed laser light L1, processing marks MT (FIG. 4) by the processed laser light L1 are formed on the substrate S at the irradiation interval D. A scribe line is formed by cracking or extending along the machining mark MT.

When the scribe line is formed on the substrate S, the substrate S is divided along the scribe line to cut out a small substrate. Specifically, a small substrate can be cut out by applying stress or impact to the substrate S along the scribe line to divide the substrate S. That is, the small substrate is separated from the substrate S along the scribe line.
In the above-mentioned dividing step, mechanical stress or impact may be applied to the substrate S by bending the substrate S, pressing with a break bar, a roller, or the like, and heating and / or heating the substrate S. Stress or impact may be thermally applied to the substrate S by cooling or the like.

(3) Example (3-1) Irradiation conditions of processed laser light (Example 1, Example 2)
Hereinafter, an embodiment in which a scribe line is formed on the substrate S by the above scribe line forming method and a small substrate is cut out from the substrate S will be described. First, two types of examples (Example 1 and Example 2) in which the irradiation conditions of the processed laser beam L1 for forming the scribe line are different will be described.
In Examples 1 and 2, a non-alkali glass substrate (OA-10) having a thickness of 0.15 mm was used as the substrate S to be processed, and the irradiation conditions of the processed laser light L1 were set as shown in Table 1.

In order to confirm the formation state of the cross section (that is, the scribe line) of the small substrate due to the difference in the irradiation conditions of the processed laser beam L1, the cross section of the small substrate cut out in Examples 1 and 2 was observed with an optical microscope. An optical microscope image of a cross section of the small substrate of Example 1 is shown in FIG. 5A, and an optical microscope image of a cross section of the small substrate of Example 2 is shown in FIG. 5B.
As shown in these figures, the cross section of the small substrate of Example 1 showed "roughness", while the cross section of the small substrate of Example 2 did not show "roughness" and was smooth. Hereinafter, the rough cross section as shown in FIG. 5A is referred to as a “pear-skinned cross section”, and the smooth cross section as shown in FIG. 5B is referred to as a “mirror surface cross section”.

The details will be described later, but the mirror-like cross section has less large irregularities and voids than the satin-like cross section and is of high quality, and the strength of the small substrate having the mirror-like cross section is higher than that of the small substrate having the satin-like cross section. ..
Further, the small substrate having a mirror-like cross section is easier to separate from the substrate S than the small substrate having a satin-like cross section. Specifically, a small substrate having a satin-like cross section cannot be separated from the substrate S without applying a slight force, while a small substrate having a mirror-like cross section is divided only by handling the substrate S after forming a scribe line. Ru.
As described above, by forming the scribe line having the cross section of the small substrate as a mirror-like cross section, it is possible to easily cut out a small substrate having high quality and high strength.

(3-2) Irradiation cycle and irradiation interval of processed laser light (Example 3)
From the results of Examples 1 and 2, it can be seen that whether the cross section of the small substrate is a mirror-like cross section or a satin-like cross section is particularly influenced by the irradiation cycle of the processed laser beam L1 when forming the scribe line. I understand.
In Example 3, the optimum conditions (optimal irradiation cycle) of the processed laser beam L1 capable of stably forming a mirror-like cross section of the small substrate are examined. In Example 3, the irradiation cycle of the processed laser light L1 was changed in the range of 5 μs to 30 μs while the irradiation interval of the processed laser light L1 was kept constant. Further, in Example 3, the irradiation interval of the processed laser light L1 was changed in the range of 0.4 μm to 0.9 μm. Other conditions are the same as in Examples 1 and 2.

In Table 2, a cross section of a small substrate cut out by irradiating a non-alkali glass substrate with a thickness of 0.15 mm with a processed laser beam L1 having a different irradiation cycle and irradiation conditions to form a scribing line is evaluated by observation with an optical microscope. The result is shown. In Table 2, "○" indicates that almost the entire cross section was a mirror-like cross section, "Δ" indicates that a part of the cross section was a mirror-like cross section, and "×" indicates that almost the entire cross section was a mirror-like cross section. Indicates that was a satin-like cross section.

As shown in Table 2, when a non-alkali glass substrate having a thickness of 0.15 mm is used, the irradiation interval is within the range of 0.4 μm to 0.7 μm and the irradiation cycle is within the range of 5 μs to 25 μs. As a result, a mirror-like cross section could be formed on at least a part of the cross section of the small substrate.
More preferably, by setting the irradiation interval within the range of 0.5 μm to 0.7 μm and the irradiation cycle within the range of 13 μs to 25 μs, almost the entire cross section of the small substrate is a mirror-like cross section, and the small substrate is formed. Was able to form a scribe line that can be easily separated from the substrate S.

When the irradiation interval of the processed laser light L1 is 0.4 μm or less, the state of the mirror-like cross section tends to be non-uniform, and it tends to be difficult to separate the small substrate from the substrate S. Further, when the irradiation interval was larger than 0.7 μm, the ratio of the satin-like cross section in the cross section of the small substrate increased.

As described above, in Examples 1 to 3, the beam diameter of the processed laser light L1 in the substrate S is 1 μm. Therefore, when the processed laser light L1 is irradiated at the above irradiation interval, it is a part of the processed laser light L1. Is irradiated in duplicate. The degree of overlap of irradiation of the processed laser beam L1 can be expressed as 1-irradiation interval / beam diameter by using the ratio of the irradiation interval to the beam diameter (irradiation interval / beam diameter). When the ratio of the irradiation interval to the beam diameter (irradiation interval / beam diameter) is smaller than 1, a part of the processed laser beam L1 is irradiated in an overlapping manner, and the smaller the ratio, the larger the degree of overlap.

The optimum condition of the irradiation interval of the processed laser beam L1 in the above-mentioned Example 3 is that the ratio of the irradiation interval to the beam diameter is in the range of 0.4 to 0.7 (multiplicity is 30% to 60%), more preferably 0. It can also be expressed as being in the range of .5 to 0.7 (multiplicity is 30% to 50%). That is, in order to make the cross section of the small substrate a mirror-like cross section, it is preferable to irradiate a part of the processed laser beam L1 in an overlapping manner so that the degree of overlap is in the range of 30% or more and 60% or less.

(3-3) Processing into substrates having different thicknesses (Example 4)
In Example 4, it is attempted whether a small substrate having a mirror-like cross section can be cut out even when a substrate having a thickness different from that of the substrates used in Examples 1 to 3 is used. In Example 4, a non-alkali glass substrate (OA-10) having a thickness of 0.5 mm was used as the substrate S to be processed.
Further, the output of the processed laser light L1 is 3.7 W, the beam diameter is 1 μm, and the irradiation cycle and the irradiation interval are changed in the same manner as in Example 3, and the processed laser light L1 for the substrate S having a thickness of 0.5 mm is obtained. We searched for the optimum irradiation conditions.

In Table 3, a cross section of a small substrate cut out by irradiating a non-alkali glass substrate with a thickness of 0.5 mm with a processed laser beam L1 having a different irradiation cycle and irradiation conditions to form a scribing line is evaluated by observation with an optical microscope. The result is shown. The meanings of "○", "Δ", and "×" in Table 3 are the same as the meanings of these symbols in Table 2.

As shown in Table 3, when a non-alkali glass substrate having a thickness of 0.5 mm is used, the irradiation interval is 0.4 μm to 0.9 μm (the ratio of the irradiation interval to the beam diameter is 0.4 to 0.9 (). By setting the irradiation cycle within the range of 10% to 60%)) and the irradiation period within the range of 15 μs to 50 μs, it was possible to form a mirror-like cross section at least a part of the cross section of the small substrate.
More preferably, the irradiation interval is in the range of 0.4 μm to 0.6 μm (the ratio of the irradiation interval to the beam diameter is 0.4 to 0.6 (multiplicity is 40% to 60%)), and the irradiation cycle is 15 μs. Within the range of about 40 μs, almost the entire cross section of the small substrate was a mirror-like cross section, and a scribe line that easily separates the small substrate from the substrate S could be formed.

Further, when a substrate having a thickness of 0.5 mm is used, the pulse energy of the processed laser beam L1 is about ½ of the pulse energy conventionally used for forming a scribe line on the same substrate. Also, it was possible to form a scribe line for cutting out a small substrate having a mirror-like cross section. That is, it is advantageous to make the cross section of the small substrate a mirror-like cross section in that the energy required for manufacturing the small substrate can be made smaller than before.

(4) Data analysis Hereinafter, the analysis results of Examples 1 to 4 will be described. Regarding the relationship between the irradiation interval and irradiation cycle of the processed laser light L1 obtained in Examples 3 and 4 and the formation state of the mirror-like cross section, the irradiation interval is set to the X axis (horizontal axis) and the irradiation cycle is set to the Y axis (vertical axis). When plotted on the graph, the result is as shown in FIG. FIG. 6 is a diagram showing the results of plotting the relationship between the irradiation interval and irradiation cycle of the processed laser beam and the formation state of the mirror-like cross section on a graph.

In FIG. 6, white circles represent irradiation conditions (irradiation interval, irradiation cycle) when almost the entire cross section of a substrate having a thickness of 0.15 mm has a mirror-like cross section. The white triangles represent the irradiation conditions when a part of the cross section of the substrate having a thickness of 0.15 mm has a mirror-like cross section.
The hatched circles represent the irradiation conditions when almost the entire cross section of the substrate having a thickness of 0.5 mm has a mirror-like cross section. The hatched triangles represent irradiation conditions when a part of the cross section of a substrate having a thickness of 0.5 mm has a mirror-like cross section.

As shown in FIG. 6, the irradiation cycle capable of forming a mirror-like cross section in at least a part of the cross section of the small substrate is in the range of a predetermined lower limit or more, and this lower limit tends to increase as the irradiation interval increases. Can be seen.
Specifically, the irradiation cycle in which a mirror-like cross section can be formed on at least a part of the cross section of the small substrate is Y = 6 in the graph of FIG. 6 in which the irradiation interval is X (μm) and the irradiation cycle is Y (μs). It is preferably present above the straight line with 0.0 * X, and more preferably above the straight line with Y = 6.0 * X + 2.0.

That is, the relationship between the irradiation cycle and the irradiation interval in which a mirror-like cross section can be formed on at least a part of the cross section of the small substrate is as follows, when the irradiation cycle is Y (μs) and the irradiation interval is X (μm), Y ≧ 6. It is preferable to satisfy 0 * X, and it is more preferable to satisfy Y ≧ 6.0 * X + 2.0.

Further, the combination of the irradiation interval (X (μm)) and the irradiation period (Y (μs)) in which almost the entire cross section of the small substrate becomes a stable mirror-like cross section, that is, the plot of circles in the graph of FIG. Is more concentrated above the straight line with Y = 20.0 * X + 3.0.
That is, the relationship between the irradiation cycle and the irradiation interval, in which almost the entire cross section of the small substrate is stably mirrored, is Y ≧ 20 when the irradiation cycle is Y (μs) and the irradiation interval is X (μm). It is particularly preferable to satisfy 0.0 * X + 3.0.

On the other hand, the upper limit of the irradiation cycle capable of forming a mirror-like cross section in at least a part of the cross section of the small substrate was 50 μs. That is, the irradiation cycle in which a mirror-like cross section can be formed on at least a part of the cross section of the small substrate is Y = 50.0 in the graph of FIG. 6 in which the irradiation interval is X (μm) and the irradiation cycle is Y (μs). It exists below the straight line of. In other words, the irradiation cycle is preferably 50.0 μs or less.

Further, the combination of the irradiation interval (X (μm)) and the irradiation period (Y (μs)) in which almost the entire cross section of the small substrate becomes a stable mirror-like cross section, that is, the plot marked with a circle in the graph of FIG. Is concentrated below the straight line with Y = -10.0 * X + 45.0 and more concentrated below the straight line with Y = -10.0 * X + 32.0.
That is, the relationship between the irradiation cycle and the irradiation interval, in which almost the entire cross section of the small substrate is stably mirrored, is Y ≦ − when the irradiation cycle is Y (μs) and the irradiation interval is X (μm). It is more preferable to satisfy 10.0 * X + 45.0, and it is particularly preferable to satisfy Y ≦ -10.0 * X + 32.0.

Summarizing the above, the relationship between the irradiation cycle and the irradiation interval that can form a mirror-like cross section on the cross section of the small substrate is 6.0 * X ≦ when the irradiation cycle is Y (μs) and the irradiation interval is X (μm). It is preferable to satisfy Y ≦ 50, more preferably to satisfy 6.0 * X + 2.0 ≦ Y ≦ 50, and further to satisfy 20.0 * X + 3.0 ≦ Y ≦ -10.0 * X + 45.0. It is preferable to satisfy 20.0 * X + 3.0 ≦ Y ≦ -10.0 * X + 32.0.

From the graph of FIG. 6, it can be seen that the plot of the irradiation conditions in which the mirror-like cross section is formed in at least a part of the cross section has an irradiation interval of 0.1 μm or more and 1.0 μm or less. In particular, it is concentrated in the range of 0.4 μm or more and 0.6 μm or less.
From this, the irradiation interval of the processed laser beam L1 for cutting out a small substrate having a mirror-like cross section is preferably 0.1 μm or more, more preferably 0.2 μm or more, and more preferably 0.3 μm or more. It can be seen that it is more preferably present, and it is particularly preferable that it is in the range of 0.4 μm or more and 0.6 μm or less.

On the other hand, when the irradiation cycle is examined in the same manner as above, the plot of the irradiation condition in which the mirror-like cross section is formed in at least a part of the cross section exists within the range where the irradiation cycle is 1.2 μs or more and 50 μs or less. There is. Further, the irradiation cycle is more concentrated within the range of 1.8 μs or more and 40 μs or less. In particular, the irradiation cycle is concentrated in the range of 10.0 μs or more and 40.0 μs or less.
From this, the irradiation cycle of the processed laser beam L1 for cutting out a small substrate having a mirror-like cross section is preferably in the range of 1.2 μs or more and 50 μs or less, and is preferably 1.8 μs or more and 40 μs. It can be seen that it is more preferably within the following range, and particularly preferably within the range of 10.0 μs or more and 40.0 μs or less.

As shown in Examples 1 to 4 above, the irradiation cycle and the irradiation interval at which the mirror-shaped cross section is formed are within a predetermined range. In order to form a mirror-like cross section on the cross section of the small substrate, it is necessary to irradiate one pulse of the processed laser light L1 and the next one pulse of the processed laser light L1 at the time of forming the scrib line. This means that the spacing between them needs to be optimized.

(5) Detailed analysis of mirror-like cross section and satin-like cross section (5-1) Electron microscope observation The mirror-like cross section and satin-like cross section are further detailed by methods other than optical microscope observation of the mirror-like cross section and satin-like cross section. The result of the analysis will be explained.
First, the mirror-like cross section and the satin-like cross section were observed with an electron microscope (Scanning Electron Microscope, SEM). The observation results will be described below. In the present embodiment, the vicinity of the scrib line forming portion of the small substrate was observed with an electron microscope to obtain an electron microscope image including the scrib line, the surface of the small substrate, and the cross section of the small substrate.

FIG. 7A is an electron microscope image of a small substrate including a mirror-like cross section. FIG. 7B is an electron microscope image of a small substrate including a satin-like cross section.
As shown in these figures, it can be seen that the mirror-shaped cross section is smoother than the satin-shaped cross section without forming large irregularities. Further, it can be seen that the scribe line when the mirror-shaped cross section is formed is smooth without large unevenness as compared with the scribe line when the satin-shaped cross section is formed.

Further, in the satin-like cross section, a void called a "void" was observed in a part of the cross section. Such voids were not found in the mirror-like cross section. FIG. 8 is a diagram showing an example of an electron microscope image of a void existing in a satin-like cross section.

(5-2) Measurement of surface roughness (center line average roughness: Ra) Next, using a laser microscope, the surface roughness of the satin-like cross section and the surface roughness of the mirror-like cross section were measured as specific numerical values. The measurement results will be described below.
As an example, the surface roughness of the satin-like cross section was about 0.1 μm, while the surface roughness of the mirror-like cross section was about 0.01 μm to 0.05 μm. That is, the surface roughness of the mirror-like cross section was about 1/10 to 1/2 of the surface roughness of the satin-like cross section.

(5-3) Measurement of bending strength Further, the bending strength of the small substrate having a satin-like cross section and the bending strength of the small substrate having a mirror-like cross section were measured. The measurement results will be described below. In this embodiment, the bending strength (referred to as end face strength) of a small substrate cut out from a non-alkali glass substrate having a thickness of 0.15 mm was measured by a four-point bending test.
In the present embodiment, as shown in FIG. 9, in the test apparatus 200 having the pair of upper fulcrum members 201 and the pair of lower fulcrum members 203, the space between the upper fulcrum member 201 and the lower fulcrum member 203 is small. A four-point bending test of the small substrate SS was performed by sandwiching the substrate SS and moving the pair of upper fulcrum members 201 toward the lower fulcrum member 203. FIG. 9 is a diagram showing an example of a method for carrying out a four-point bending test.

In the test apparatus 200 shown in FIG. 9, the distance d1 between the pair of upper fulcrum members 201 is 10 mm, the distance d2 between the pair of lower fulcrum members 203 is 20 mm, and the moving speed of the upper fulcrum member 201 is 1 mm per minute. As a result of a four-point bending test of the small substrate, the end face strength of the small substrate having a satin-like cross section is in the range of 100 MPa to 180 MPa, while the end face strength of the small substrate having a mirror-like cross section is 180 MPa or more. It was within the range of 380 MPa or less.
As described above, the small substrate having a mirror-like cross section had about twice the end face strength as that of the small substrate having a satin-like cross section.

(5-4) Summary of test results From the above test results, it can be seen that the mirror-shaped cross section has less large irregularities and voids than the satin-finished cross section, and is of high quality, and the strength of the small substrate can be increased. Further, the small substrate can be easily cut out from the substrate S by forming the scribe line using the irradiation conditions of the processed laser beam L1 such that the mirror-like cross section is formed.

2. 2. Other Embodiments Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications can be made without departing from the gist of the invention. In particular, the plurality of examples and modifications described in the present specification can be arbitrarily combined as needed.
In the above embodiment, the substrate S to be processed is a non-alkali glass substrate (Examples 1 to 3) having a thickness of 0.15 mm or a non-alkali glass substrate (Example 4) having a thickness of 0.5 mm. rice field. However, the processing is not limited to this, and other brittle substrates of arbitrary thickness can be processed by optimizing the irradiation conditions of the processed laser beam L1 based on the mechanism for forming the mirror-like cross section described above. Even in this case, it is possible to form a scribe line capable of cutting out a small substrate having a mirror-like cross section.

INDUSTRIAL APPLICABILITY The present invention can be widely applied to a method and an apparatus for forming a scribe line by irradiating a brittle substrate such as glass with a laser beam.

100 Scribline forming device 1 Laser system 11 Laser device 11a Laser oscillator 11b Laser control unit 13 Transmission optical system 131 Axicon lens 133 Reduction optical system 15 Drive mechanism 3 Machining table 5 Table drive unit 7 Control unit 200 Test device 201 Upper fulcrum member 203 Lower fulcrum member L1 Machined laser light L2 Laser light L3 Ring beam P Plasma S Substrate SS Small substrate

Claims (19)

A scribe line forming method for forming a scribe line for cutting out a small substrate from a brittle substrate.
The brittle substrate is provided with a step of irradiating the brittle substrate with a processed laser beam having a predetermined beam diameter at a predetermined irradiation interval at a predetermined irradiation cycle along a processing line forming the scribe line on the brittle substrate. ,
The irradiation interval (X (μm)) and the irradiation cycle (Y (μs)) satisfy the condition of Y ≧ 6.0X.
How to form a scribe line. The scrivener line forming method according to claim 1, wherein the irradiation interval (X (μm)) and the irradiation cycle (Y (μs)) satisfy the condition of Y ≧ 6.0X + 2.0. The scribe line forming method according to claim 1 or 2, wherein the irradiation cycle is in the range of 50 μs or less. The scrivener line forming method according to any one of claims 1 to 3, wherein the irradiation interval is in the range of 0.1 μm or more. The scribe line forming method according to claim 4, wherein the irradiation interval is in the range of 0.2 μm or more. The scrivener line forming method according to claim 5, wherein the irradiation interval is in the range of 0.3 μm or more. The scrivener line forming method according to any one of claims 1 to 6, wherein the irradiation cycle is in the range of 1.2 μs or more and 50 μs or less. The scrivener line forming method according to claim 7, wherein the irradiation cycle is in the range of 1.8 μs or more and 40 μs or less. The scrivener line forming method according to any one of claims 1 to 8, wherein the beam diameter is in the range of 0.2 μm or more and 10 μm or less. The scrivener line forming method according to any one of claims 1 to 9, wherein the degree of overlap of irradiation of the processed laser light is in the range of 30% or more and 60% or less. The scribble line forming method according to any one of claims 1 to 10, wherein the processed laser light is a pulse-shaped laser light having a pulse width of 20 picoseconds or less. The step of irradiating the processed laser light is
A step of converting a laser beam output from a laser device at a predetermined irradiation cycle into a ring beam having a constant ring width by an axicon lens, and a step of converting the laser beam into a ring beam having a constant ring width.
A step of injecting the ring beam into the reduced optical system to adjust the beam diameter of the processed laser beam on the brittle substrate, and a step of adjusting the beam diameter.
The method for forming a scribe line according to any one of claims 1 to 11. It is a method for dividing a brittle substrate to cut out a small substrate from the brittle substrate.
A processing laser beam having a predetermined beam diameter is irradiated to the brittle substrate at a predetermined irradiation interval at a predetermined irradiation cycle along a processing line forming a scribe line on the brittle substrate, and the irradiation interval (X). (Μm)) and the scribe line forming step in which the irradiation cycle (Y (μs)) satisfies the condition of Y ≧ 6.0X.
A division step of applying stress or impact along the scribe line formed in the scribe line forming step to divide the brittle substrate and cutting out the small substrate is provided.
A method for dividing a brittle substrate. A scribe line forming device for forming a scribe line for cutting out a small substrate from a brittle substrate.
A laser system that outputs processed laser light with a predetermined beam diameter at a predetermined irradiation cycle, and
With a driving unit that moves the brittle substrate with respect to the laser system in order to irradiate the brittle substrate with the processed laser light at a predetermined irradiation interval along the processing line forming the scribe line on the brittle substrate. , Equipped with
The irradiation interval (X (μm)) and the irradiation cycle (Y (μs)) satisfy the condition of Y ≧ 6.0X.
Scrivener forming device. The scribe line forming apparatus according to claim 14, wherein the irradiation cycle is in the range of 50 μs or less. The scribe line forming apparatus according to claim 14 or 15, wherein the irradiation interval is in the range of 0.1 μm or more. The scribe line forming apparatus according to any one of claims 14 to 16, wherein the irradiation cycle is in the range of 1.2 μs or more and 50 μs or less. The laser system is
A laser device that outputs laser light in the predetermined irradiation cycle, and
An axicon lens that converts the laser beam into a ring beam having a constant ring width, and
A reduction optical system in which the ring beam is incident and the processed laser beam having an adjusted beam diameter on the brittle substrate is formed from the incident ring beam.
The scribe line forming apparatus according to any one of claims 14 to 17. A small substrate obtained by irradiating a brittle substrate made of glass, quartz, or sapphire with a laser beam having a wavelength of 750 nm to 2500 nm to form a scribing line, and dividing the brittle substrate along the scribing line. A small substrate having a mirror-like cross section having a surface roughness of 0.05 μm or less and an end face strength of 180 MPa or more in at least a part of the cross section.

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