JP2013119510A - Method for processing glass substrate with laser - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method by which processing of a glass substrate such as drilling or groove forming can be performed more rapidly with a laser.SOLUTION: The method for processing a glass substrate with a laser includes (a) a step of subjecting the glass substrate to laser processing in a state where the glass substrate is heated. When the softening point of the glass substrate is represented by Ts(°C) and the glass transition temperature of the glass substrate by Tg(°C), the glass substrate is subjected to laser processing in a state where the glass substrate is heated at a temperature of Tg or higher to a temperature lower than Ts.

Description

  The present invention relates to a method for processing a glass substrate using a laser.

Conventionally, a technique for forming a structure such as a recess, a groove, a through hole, and / or a through groove on a glass substrate using a laser is known. For example, Non-Patent Document 1 describes a method of drilling or grooving glass using an excimer laser.
Is described.

"Excimer Laser Technology", edited by Dick Basting, published by LAMBDA PHYSIK

  As described above, a technique for forming various structures on a glass substrate using a laser is known. However, in the field of laser processing technology for glass substrates, there is a demand for further improvement in processing speed in order to efficiently form structures such as through holes and / or through grooves with glass substrates.

  This invention is made | formed in view of such a background, and this invention aims at provision of the method which can process a glass substrate more rapidly using a laser.

In the present invention, a method of processing a glass substrate using a laser,
(A) A method is provided that includes a step of performing laser processing on the glass substrate while the glass substrate is heated.

  Here, in the method according to the present invention, in the step (a), when the softening point of the glass substrate is Ts (° C.), the glass substrate is heated to a temperature higher than room temperature and lower than the softening point Ts. May be.

  In the method according to the present invention, in the step (a), the glass substrate may be heated to a temperature higher than Tg and lower than Ts when the glass transition temperature of the glass substrate is Tg (° C.). good.

  In the method according to the present invention, in the step (a), the glass substrate may be heated to a temperature in the range of Tg to Td, where Td (° C.) is the yield point of the glass substrate.

  In the method according to the present invention, the laser may be a laser having a wavelength of 400 nm or less.

  In the method according to the present invention, at least one structure selected from the group consisting of a recess, a through hole, a through groove, a non-through hole, and a non-through groove is formed on the glass substrate by the step (a). It may be formed.

  In the method according to the present invention, one of the at least one structures may be formed by performing the step (a) once.

  Alternatively, in the method according to the present invention, a plurality of the at least one structure may be formed by performing the step (a) once.

  In the method according to the present invention, the glass substrate may be heated by a heating unit, and the heating unit may be at least one selected from the group consisting of a laser beam and a heater.

  In the present invention, a method capable of processing a glass substrate more rapidly using a laser can be provided.

It is a schematic flowchart of an example of the laser processing method of the glass substrate by this invention. It is a schematic block diagram of the apparatus which can be used in the case of the laser processing method of the glass substrate by this invention. 4 is a graph showing the relationship between the number of shots and the processing depth at each heating temperature in Example 1. 3 is a graph showing a relationship between a heating temperature and a processing rate increase rate in Example 1. 10 is a graph showing the relationship between the number of shots and the processing depth at each heating temperature in Example 2. It is the graph which showed the relationship between the heating temperature in Example 2, and a processing rate increase rate.

  The present invention will be described below.

In the present invention,
A method of processing a glass substrate using a laser,
(A) A method is provided that includes a step of performing laser processing on the glass substrate while the glass substrate is heated.

  As described above, in the field of processing a glass substrate using a laser, further improvement in processing efficiency is required.

  The method according to the present invention is characterized in that laser processing of the glass substrate is performed while the glass substrate is heated. In this case, the bonding of atoms can be easily broken by heating the glass substrate, and the processing speed for the glass substrate can be increased. Therefore, in the present invention, it is possible to improve the processing efficiency by the laser.

  Moreover, in the processing method of the glass substrate by the conventional laser, a glass substrate is heated locally by the laser irradiation with respect to the glass substrate of room temperature. Furthermore, the irradiation position of the glass substrate is locally cooled by not irradiating the laser thereafter. Therefore, in the conventional method, particularly when laser irradiation is repeatedly performed on the same portion (hereinafter, referred to as “repetitive irradiation processing”), the glass substrate is subjected to thermal shock, which causes cracks and / or damage to the glass substrate. Or defects such as cracks may occur. In particular, in the case of processing with a high repetition frequency, defects such as cracks may occur remarkably.

  Furthermore, the conventional method for processing a glass substrate using a laser has a problem in that residual stress tends to be accumulated on the processed glass substrate for the same reason. For this reason, during storage of the glass substrate after processing, defects such as cracks and / or cracks (so-called “post-cracking”) may occur in the glass substrate.

  On the other hand, in the method according to the present invention, since the glass substrate is heated during the laser processing, a local temperature increase at the laser irradiation position of the glass substrate and a rapid temperature decrease thereafter. Can be suppressed. Therefore, in the method according to the present invention, even when repeated irradiation processing is performed, local thermal shock is suppressed from being applied to the glass substrate, and generation of cracks and / or cracks can be significantly suppressed. An additional effect is possible.

  In the method according to the present invention, since the glass substrate is heated during processing, residual stress is not easily accumulated on the glass substrate. For this reason, the method according to the present invention provides the additional effect that the problem of “post-cracking” can be significantly suppressed.

  Here, in the laser processing method for a glass substrate according to the present invention, the temperature of the glass substrate during heating is preferably higher than room temperature and less than the softening point Ts of the glass substrate. When the temperature of the glass substrate is heated to a temperature equal to or higher than the softening point Ts, the glass substrate may be warped or deformed. Moreover, there is a possibility that a laser irradiation position shift occurs and a serious problem occurs in processing.

  The temperature of the glass substrate during heating is more preferably in the range of not less than the transition temperature Tg and less than the softening point Ts, where Tg is the glass transition temperature of the glass substrate. In particular, the temperature of the glass substrate during heating is more preferably in the range from the transition temperature Tg to the yield point Td, where Td is the yield point of the glass substrate. When the heating temperature of the glass substrate is adjusted to such a range, an extremely large laser processing speed can be obtained.

  In the present application, the softening point Ts, the glass transition temperature Tg, and the yield point Td of the glass substrate mean values measured by the following methods.

  In the thermal expansion curve showing the relationship between temperature and sample elongation obtained when a fully annealed sample is heated at a constant rate of 4 ° C. per minute using a thermomechanical analyzer (TMA), Let the temperature corresponding to the intersection which extended the linear part with the side be the glass transition point Tg. Further, in the thermal expansion curve, the temperature at which the expansion stops apparently is defined as a yield point Td. The softening point Ts is measured using a fiber elongation method defined in JIS-R3104 and ASTM-C338.

  In the laser processing method for a glass substrate according to the present invention, various features such as a recess, a through hole, a through groove, a non-through hole, and / or a non-through groove can be formed on the glass substrate more efficiently than before. it can.

(One aspect of laser processing method of glass substrate according to the present invention)
Hereinafter, a specific example of a laser processing method for a glass substrate according to the present invention will be described with reference to the drawings.

  FIG. 1 shows a schematic flowchart of an example of a laser processing method for a glass substrate according to the present invention.

As shown in FIG. 1, in one aspect according to the present invention, a laser processing method for a glass substrate comprises:
(1) a step of preparing a glass substrate (step S110);
(2) heating the glass substrate (step S120);
(3) irradiating the glass substrate with a laser to process the glass substrate (step S130);
You may have.

  Hereinafter, each step will be described in detail.

(Step S110)
First, a glass substrate to be processed is prepared.

  The glass substrate has, for example, a first surface and a second surface. The composition of the glass substrate is not particularly limited. The glass substrate may be, for example, soda lime glass, borosilicate glass, silica glass, and alkali-free glass.

  The thickness of the glass substrate is not particularly limited. The thickness of the glass substrate may be, for example, in the range of 0.1 mm to 3 mm.

(Step S120)
Next, the glass substrate prepared in step S110 is heated.

  The heating method is not particularly limited. The glass substrate may be heated directly or indirectly by a heating means such as a heater.

Examples of the direct heating method include a method in which the glass substrate is disposed so as to be in direct contact with a heat source such as a hot plate. In addition, the glass substrate may be irradiated with a laser (for example, a low energy laser such as a CO ₂ laser) over a wide range, thereby heating the entire glass substrate.

  Moreover, as an indirect heating method, the method etc. which implement the process of a glass substrate in the chamber by which temperature control was carried out are mentioned.

  The heating temperature of the glass substrate is not particularly limited as long as it is higher than room temperature.

  However, in general, the increase in laser processing speed becomes more remarkable at a high temperature of 200 ° C. or higher. As described above, usually, a temperature lower than the softening point Ts of the glass substrate is selected as the heating temperature. As described above, the heating temperature is preferably in the range of Tg or more and less than Ts, where Tg is the glass transition temperature of the glass substrate. In particular, as described above, the heating temperature is more preferably in the range of Tg to Td, where Td is the yield point of the glass substrate.

(Step S130)
Next, with the glass substrate heated, the glass substrate is irradiated with laser, whereby the glass substrate is processed.

  The type of laser is not particularly limited, but lasers are, for example, excimer laser (XeCl: wavelength 308 nm, KrF: wavelength 248 nm, ArF: wavelength 193 nm), YAG laser (wavelength 1064 nm), YVO4 laser (wavelength 1064 nm), titanium A sapphire laser (wavelength 800 nm) or a carbon dioxide laser (wavelength 10.6 μm) may be used. The YAG laser and the YVO4 laser may be, for example, a second harmonic, a third harmonic, a fourth harmonic, or a fifth harmonic laser in addition to the fundamental wave described above. For example, a second harmonic YAG and YVO4 laser has a wavelength of 532 nm, a third harmonic YAG and YVO4 laser has a wavelength of 355 nm, and a fourth harmonic YAG and YVO4 laser has a wavelength of 266 nm. The fifth harmonic YAG and YVO4 lasers have a wavelength of 213 nm.

  In particular, excimer lasers with a wavelength of 400 nm or less (XeCl: wavelength 308 nm, KrF: wavelength 248 nm, ArF: wavelength 193 nm), YAG laser and YVO4 laser third harmonic, fourth harmonic, and fifth harmonic lasers are thermally Since there is little influence, there is little fear of crack generation and post-cracking, which is preferable.

  The irradiating laser may have an on / off repetitive waveform or a modulated repetitive waveform.

  Moreover, the laser irradiated to the glass substrate may be scanned with respect to the glass substrate. Thereby, it becomes possible to perform the process which forms a more complicated characteristic object with respect to a glass substrate.

  By the laser irradiation or a combination of laser irradiation and laser scanning (hereinafter simply referred to as “laser irradiation”), the glass substrate has a recess, a through hole, a through groove, a non-through hole, and / or Alternatively, various features such as non-through grooves are formed.

  Note that the number of laser spots irradiated onto the glass substrate at one time may be one or plural. When the number of laser spots is one, a single feature is formed on the glass substrate by "one time" laser processing. On the other hand, when there are a plurality of laser spots, a plurality of features can be formed on the glass substrate by “one time” laser processing.

  Here, the number of times of laser processing is “one time” means that the step of forming the final-shaped feature is performed once at a desired position on the glass substrate. Therefore, it should be noted that the number of times of laser processing does not mean the number of times the laser is actually irradiated on the glass substrate, that is, the number of shots of the laser.

  For example, when there are three laser spots that are irradiated onto the glass substrate at a time, it is possible to finally form and form three features on the glass substrate by performing “once” laser processing. In this case, “one-time” laser processing includes irradiating the same three locations with the laser for the required number of times.

  Similarly, for example, when the number of laser spots irradiated onto the glass substrate is one, when processing and forming three features on the glass substrate, a total of “three times” laser processing is performed. To be implemented.

(Apparatus that can be used in the method according to the invention)
Next, an apparatus that can be used in the above-described laser processing method for a glass substrate according to the present invention will be described.

  In FIG. 2, the structure of the apparatus which can be used for the laser processing method of the glass substrate by this invention is shown typically.

  As shown in FIG. 2, an apparatus 200 that can be used in the laser processing method for a glass substrate according to the present invention includes a main laser 220 emitted from a laser light source (not shown), and a plurality of branched lasers. Diffractive optical element 230 that branches into light 260A, 260B, and 260C, lens 250 that converges each branched laser beam 260A, 260B, and 260C to a desired position on glass substrate 210, and heating that can heat glass substrate 210 Device 290.

  The laser light source is not particularly limited. For example, an excimer laser light source (XeCl: wavelength 308 nm, KrF: wavelength 248 nm, ArF: wavelength 193 nm), YAG laser light source (wavelength 1064 nm), YVO4 laser light source (wavelength 1064 nm), titanium sapphire A laser light source (wavelength 800 nm), a carbon dioxide laser light source (wavelength 10.6 μm), or the like may be used. The YAG laser light source and the YVO4 laser light source may be, for example, a second harmonic wave source or a third harmonic wave laser source in addition to the fundamental wave described above. For example, a second harmonic YAG laser has a wavelength of 532 nm, and a third harmonic YAG laser has a wavelength of 355 nm.

  Although the output of the main laser 220 is not particularly limited, the larger the power of the main laser 220 is, the more advantageous it is because more branched laser beams 260A, 260B, and 260C can be obtained at one time.

  The main laser 220 may have an ON / OFF repetitive waveform or a modulated repetitive waveform.

  The diffractive optical element 230 may be any element as long as it can divide one main laser 220 into a plurality of branched laser beams 260A, 260B, and 260C. A splitter or the like may be used.

  When the glass substrate 210 is processed using the apparatus 200 having such a configuration, first, the glass substrate 210 having the first surface 212 and the second surface 214 is heated by the heating device 290. In the example of FIG. 2, the heating device 290 is disposed in contact with the second surface 214 of the glass substrate 210.

  Next, after it is confirmed that the glass substrate 210 is heated and reaches a predetermined temperature, the main laser 220 is emitted from the laser light source toward the first surface 212 of the glass substrate 210. In the diffractive optical element 230, the main laser 220 is branched into, for example, three branched laser beams 260 (260A, 260B, 260C).

  The branched laser beams 260A, 260B, and 260C are converged by the lens 250 to become branched laser beams 265A, 265B, and 265C, respectively. Further, these branched laser beams 265A, 265B, and 265C form focal points 270A, 270B, and 270C on the first surface 212 of the glass substrate 210, respectively.

  The spot diameters of the focal points 270A, 270B, and 270C vary depending on the performance of the lens 250 and the like, but may be, for example, about 0.1 μm to 100 μm.

  The distance between the focal points 270A, 270B, and 270C is not particularly limited. The distance between the focal points 270A, 270B, and 270C is, for example, in the range of 20 μm to 400 μm, and may be in the range of 50 μm to 250 μm.

  Note that when a complicated feature is formed on the glass substrate 210, a series of branched laser beams 265A, 265B, and 265C may be scanned in a desired direction. Further, in the case where a feature such as a through hole and / or a through groove is formed in the glass substrate 210, the glass substrate 210 and the heating device 290 can be prevented from being damaged by the branched laser beams 265A, 265B, and 265C. A spacer may be disposed between them.

  Through the above steps, the glass substrate 210 is processed, and various features are formed on the glass substrate 210.

  In the example of FIG. 2, by using the apparatus 200, three features are formed by one laser processing.

  However, the configuration of the apparatus that can be used in the method according to the present invention is not limited to such an embodiment. For example, in the apparatus 200, the number of the branched laser beams 265 may be two or four or more. In this case, two or four or more features can be formed by one laser processing.

  Further, when the main laser 220 is used as it is without using the diffractive optical element 230, a single feature can be formed by one laser processing. Such an aspect is particularly beneficial when the energy of the laser beam used is relatively small.

  Further, when a laser having a large beam size such as an excimer laser is used, a method in which a mask pattern is reduced and projected onto a glass substrate through a mask on which a pattern is formed is preferable. In this case, it becomes possible to process many places at once.

  Next, examples according to the present invention will be described.

Example 1
Laser processing was performed on the glass substrate in a state where the glass substrate was heated to each temperature by the following method, and the processing speed was evaluated.

  A commercially available soda lime glass was used for the glass substrate. The size of the glass substrate was 25 mm long × 75 mm wide × 0.2 mm thick. The soda lime glass has a glass transition temperature Tg of about 540 ° C., a yield point Td of about 580 ° C., and a softening point Tg of about 740 ° C.

An excimer laser having a wavelength of about 193 nm was used as the processing laser. Excimer laser light was reduced and projected onto one surface of the glass substrate through a mask, and processing along the mask pattern was performed. A plurality of holes having a diameter of about 60 μm were formed. The repetition frequency of the pulse wave was 50 Hz, and the fluence was 4 J / cm ² .

  A commercially available hot plate was used for heating the glass substrate, and laser processing of the glass substrate was performed with the glass substrate placed on the hot plate. The heating temperature was 200 ° C, 400 ° C, and 600 ° C. For comparison, the same laser processing was performed on a non-heated (ie, room temperature) glass substrate.

  The glass substrate was taken out every predetermined number of laser shots, and the processing depth of the laser irradiated portion was measured.

  Table 1 summarizes the measurement results of the processing depth obtained at each temperature.

図３には、各加熱温度におけるショット数と加工深さの関係を示す。この図３から、いずれの加熱温度においても、加工深さは、ショット数の増加に伴い、ほぼ直線的に増加する傾向にあることがわかる。

FIG. 3 shows the relationship between the number of shots and the processing depth at each heating temperature. From FIG. 3, it can be seen that at any heating temperature, the processing depth tends to increase almost linearly as the number of shots increases.

  In FIG. 3, the slope of the straight line obtained from the relationship between the number of shots at each heating temperature and the processing depth is shown in the “straight line” column of Table 1 above.

  FIG. 4 shows the relationship between the heating temperature and the processing speed. In FIG. 4, the processing speed on the vertical axis was calculated from the slope of the straight line in the measurement results at each heating temperature in FIG. In addition, the vertical axis | shaft was displayed by the increase rate with respect to this on the basis of the processing speed in the glass substrate of room temperature (namely, non-heating state).

  FIG. 4 shows that when the glass substrate is heated, an improvement in processing speed of about 10% or more can be obtained as compared with the case where the glass substrate is not heated. In particular, when the heating temperature was 400 ° C. and 600 ° C., the processing speed was improved by about 18% compared to the result in the non-heated state.

  The soda-lime glass substrate has a glass transition temperature Tg of about 540 ° C. and a yield point Td of about 580 ° C. Therefore, FIG. 4 shows that when the glass substrate is heated in the range of the glass transition temperature Tg to the yield point Td (400 ° C. to 600 ° C.), the processing speed becomes maximum.

(Example 2)
By the same method as in Example 1, laser processing was performed on the glass substrate while the glass substrate was heated to each temperature, and the processing speed was evaluated. However, in Example 2, a non-alkali glass substrate was used as the glass substrate to be processed. The glass transition temperature Tg of this glass substrate is about 660 ° C., the yield point Td is about 740 ° C., and the softening point Tg is about 880 ° C.

  Table 2 summarizes the measurement results of the processing depth obtained at each temperature.

図５には、各加熱温度におけるショット数と加工深さの関係を示す。この図５から、無アルカリガラス製の基板の場合も、加熱温度に関わらず、加工深さは、ショット数の増加に伴い、直線的に増加する傾向にあることがわかる。

FIG. 5 shows the relationship between the number of shots at each heating temperature and the processing depth. From FIG. 5, it can be seen that, even in the case of a substrate made of alkali-free glass, the processing depth tends to increase linearly as the number of shots increases, regardless of the heating temperature.

  In FIG. 5, the slope of the straight line obtained from the relationship between the number of shots at each heating temperature and the processing depth is shown in the “straight line” column of Table 2 above.

  FIG. 6 shows the relationship between the heating temperature and the processing speed. In FIG. 6, the processing speed on the vertical axis was calculated from the slope of the straight line in the measurement results at each heating temperature in FIG. In addition, the vertical axis | shaft was displayed by the increase rate with respect to this on the basis of the processing speed in the glass substrate of room temperature (namely, non-heating state).

  From FIG. 6, it can be seen that heating the glass substrate can improve the processing speed by about 5% or more compared to the case of not heating. In particular, when the heating temperature was 600 ° C. to 800 ° C., the processing speed was improved by about 11% to about 22% compared to the result in the non-heated state.

  The glass transition temperature Tg of the alkali-free glass substrate is about 660 ° C., and the yield point Td is about 740 ° C. Therefore, FIG. 6 shows that when the glass substrate is heated in the range of the glass transition temperature Tg to the yield point Td (600 ° C. to 800 ° C.), a good processing speed can be obtained.

  Thus, it has been found that the processing speed can be significantly improved in the method of laser processing a glass substrate according to the present invention.

  The present invention can be applied to a laser processing method of a glass substrate.

200 Device 210 Glass substrate 212 First surface 214 Second surface 220 Main laser 230 Diffractive optical element 250 Lens 260A, 260B, 260C Branched laser light 265A, 265B, 265C Branched laser light 270A, 270B, 270C Focus 290 Heating device

Claims (9)

A method of processing a glass substrate using a laser,
(A) A step of performing laser processing on the glass substrate while the glass substrate is heated.   2. The method according to claim 1, wherein in the step (a), the glass substrate is heated to a temperature higher than room temperature and lower than the softening point Ts, where Ts (° C.) is the softening point of the glass substrate. .   The said (a) process WHEREIN: When the glass transition temperature of this glass substrate is set to Tg (degreeC), the said glass substrate is heated to temperature lower than Ts more than Tg. Method.   In the step (a), the glass substrate is heated to a temperature in the range of Tg to Td, where Td (° C.) is the yield point of the glass substrate. The method described in 1.   The method according to claim 1, wherein the laser is a laser having a wavelength of 400 nm or less.   The step (a) forms at least one structure selected from the group consisting of a recess, a through hole, a through groove, a non-through hole, and a non-through groove on the glass substrate. 6. The method according to any one of 5.   The method according to claim 6, wherein the at least one structure is formed by performing step (a) once.   The method according to claim 6, wherein a plurality of the at least one structure are formed by performing step (a) once.   The method according to claim 1, wherein the glass substrate is heated by a heating unit, and the heating unit is at least one selected from the group consisting of a laser beam and a heater.

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