JP2000301372A - Laser processing method of transparent material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an industrially practical transparent material capable of forming fine deep holes at high speed and at low cost with high quality and high precision in various transparent materials such as glass using a low output laser beam. Provided is a laser processing method for a material. SOLUTION: A pigment 8 is adhered to a surface of a glass substrate 6 to a uniform thickness, and a Q-switched pulse oscillation YAG laser B of a single mode beam with a fundamental wave, a second harmonic or a third harmonic is directed toward the surface. Is irradiated. The pigment absorbs the laser energy of the first one or several pulses, generates a high-temperature, high-pressure plasma state on the surface of the glass substrate, and melts and removes the glass of the surface layer to form a recess 9, At the same time, its peripheral portion is transformed into a composition that easily absorbs laser light. The altered layer 10 absorbs the laser light continuously irradiated thereafter and is melted and removed, thereby forming the fine holes 11 penetrating the glass substrate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a laser processing method capable of forming fine holes, particularly through holes, in a transparent material such as glass or crystal using a laser beam. In particular, the present invention, for example, to form a number of aligned micro holes in a glass plate to form an injection hole for an inkjet printer,
The present invention relates to a laser processing method of an industrially practical transparent material used for forming a through hole for connecting an electronic component and an electrode to a glass plate of a liquid crystal panel.

[0002]

2. Description of the Related Art Conventionally, in order to perform fine drilling on a transparent material such as glass, a mechanical processing such as a processing method using a rotary grindstone, a drill, an ultrasonic wave, or a micro blast method for spraying abrasive grains. Methods and chemical methods such as wet etching using a solution are generally employed.
Recently, energy beam processing for irradiating an electron beam, an ion beam, or a laser beam has been performed.

In laser processing, a far-infrared laser such as an excimer laser or a CO ₂ laser, which is generally ultraviolet light, is used. Furthermore, there is a research report that processing with visible light or near-infrared light is possible by using a laser having a high peak output called a giant pulse. On the other hand, it is said that YAG lasers, which are relatively inexpensive, have good operability, and are easy to handle, cannot be processed because of their low absorptivity to glass materials in general.

According to a paper by Junichi Ikeno et al. On YAG laser, "YAG laser processing of quartz glass using solution" (Journal of the Japan Society of Precision Engineering, 55/2/1989, pp. 93-98), the thickness of a solution containing metal ions is reduced. When a pulsed YAG laser is irradiated onto the surface of a 1.5 mm transparent quartz glass plate by dropping or in contact with the back surface, the solution absorbs laser light and generates high heat, melting the quartz glass and penetrating it. It has been reported that holes can be formed. The same article also describes that in the case of general glass containing impurities, the through-hole can be similarly laser-processed without the above-mentioned solution simply by applying magic ink to the surface.

According to another report by Ikeno et al. (“YAG laser processing of crystallized glass”, Proceedings of the 1997 Autumn Meeting of the Japan Society for Precision Engineering, page 232), the focus was on the surface of crystallized glass. When a laser beam is irradiated together with the laser beam, a molten portion is formed inside the glass, and as soon as the output exceeds a threshold, a crack is generated and the glass is broken. Therefore, a pigment is applied to the glass surface, and a pulse oscillation YA
By irradiating a G laser beam to form a melted part on the surface and scattering it to the outside, this problem of crack generation is solved, and a through-hole is formed in a crystallized glass plate having a thickness of 4 mm. .

[0006] This processing mechanism is also described in a paper by Junichi Ikeno, "Three-dimensional drilling of glass using YAG laser" (Report of the Laser Society of Japan, No. RTM-98-4, Laser Society of Japan, January 1998) Published on the 30th, pages 23-27)
According to the fact that a damaged layer is observed in the drilled hole,
It is analyzed that the pigment absorbs the YAG laser and the glass is melted to form a deteriorated layer, and the deteriorated layer absorbs the next laser beam and proceeds.

A paper by Shigeyuki Takagi et al., "FHG-YAG
Laser Ablation ”(The Institute of Electrical Engineers of Japan, Materials for Optical and Quantum Devices Research, Material No. OQD-95-
5, pages 37-46, published March 10, 1995)
A pulsed fourth harmonic (FHG) YAG laser based on an Acoustic Q-switched YAG laser is:
Although the peak power is low, high repetition excitation on the order of kHz is possible, the controllability is good, and the reliability, ease of use,
It is reported that it has advantages such as high maintainability and that high-precision fine processing can be performed on polyimide or soda glass of a polymer material. According to Takagi et al., When processing soda glass with an excimer laser, microcracks are generated, whereas with the FHG-YAG laser, a hole having a diameter of incidence of 30 μm and a depth of 40 mm can be formed in soda glass.

Further, Kenichi Hayashi's paper "High Aspect Ratio Processing of Glass by Nd: YLF Laser Fifth Harmonic" (Laser Research, November 1997) is used for soda-lime glass and liquid crystal displays (LCD). When an ablation process was performed on a glass substrate such as an alkali-free glass using the fifth harmonic of a Nd: YLF laser, an entrance side hole diameter was 10 μm, an exit side hole diameter was 4 μm, and an aspect ratio was 100 μm.
It has been described that deep hole processing exceeding the maximum diameter was achieved, and that no crack was observed on the processed surface on both the incident side and the outgoing side. According to Hayashi, Kaoru Kikuchi reported drilling of glass using the fundamental wave of a Nd: YAG laser (Mechanical Research News 10 (1995)).
6).

[0009]

However, the above-mentioned conventional processing method has the following problems. First, in a mechanical processing method such as a micro blast method, there is a limit to miniaturization of a processing hole, and there is a possibility of causing a quality problem such as chipping, that is, a minute chipping easily occurs around an opening of the processing hole. Further, in wet etching, usable etchants may be limited depending on the material of a workpiece, and it is difficult to process a fine deep hole, and the processing speed is slow. Similarly, processing devices such as electron beams and ion beams are generally expensive and have very low processing speeds.

In the case of laser processing, an excimer laser has problems such as an expensive apparatus, high running cost, and poor maintenance of the apparatus. The CO ₂ laser performs thermal processing and has a large output.Therefore, cracks due to thermal distortion are likely to occur over a wide area around the processed part, and the quality may be impaired. Low and not suitable for microfabrication. Similarly, the giant pulse laser is expensive, and the peak output is too high, which may damage the optical system.

The pulse oscillation type YAG by Ikeno et al.
Since laser drilling requires a certain high laser output, cracks are likely to occur depending on the glass material to be processed and processing conditions, and there is a possibility that processing stability is lacking. Further, since the beam quality is low and the light-collecting characteristics are not good, it is difficult to form a hole having a diameter of 100 μm or less. On the other hand, the Takagi et al. FHG-YAG laser requires two nonlinear crystals to be placed inside and outside the laser resonator and to control them to a narrow temperature matching tolerance in order to obtain the fourth harmonic. The device itself becomes complicated and expensive,
There is a possibility that processing stability is impaired. Further, since ultraviolet light is used, there is a possibility that the nonlinear crystal, the mirror, the lens, and the like may be deteriorated.

According to Hayashi's paper mentioned above, Kaoru Kikuchi's drilling of glass with the fundamental wave of an Nd: YAG laser focuses a laser beam inside the glass and absorbs multiphotons from the back to front of the glass. Since holes are formed toward the surface, post-processing such as mechanical polishing and heat treatment is required because processing distortion remains. Furthermore, the reason why the fifth harmonic of the Nd: YLF laser is adopted is that, with the fourth harmonic, cracks are generated on the glass surface by several times of irradiation, so that good processing without cracks on the processing surface is realized for industrial applications. In order to do so, a light source with a shorter wavelength is considered necessary. However, laser processing using such a short-wavelength light source also has a problem that equipment and processing costs are similarly increased.

Accordingly, the present invention has been made in view of the above-mentioned conventional problems, and has as its object to use conventional low-power laser light of, for example, several watts at most, and to perform conventional laser processing. Provide a laser processing method for industrially practical transparent materials that can form fine deep holes at high speed, at low cost, and with high quality and high precision in various transparent materials such as glass and crystals including glass It is in.

[0014]

According to the laser processing method for a transparent material of the present invention, in order to achieve the above-mentioned object, a light absorbing substance is adhered to a surface of a workpiece made of a transparent material, and the light absorbing substance is deposited. The method is characterized in that a Q-switched pulse oscillation laser is irradiated toward the surface of the processed workpiece to form a hole in the surface.

The Q-switched pulse oscillation laser temporarily stores the stored energy of the laser and outputs it at once, and can obtain a high pulse energy of several hundred kW even with a low output of several W. When the first one or several pulses are emitted, the laser energy is absorbed by the light absorbing material,
Even in the case of glass materials that were conventionally difficult to laser-process, the high-temperature, high-pressure plasma state is generated on the surface of the workpiece, so that the glass on the surface is melted and removed to form a recess and Only the altered layer is formed without altering the peripheral portion to a composition that easily absorbs laser light, or without forming a recess on the surface of the workpiece. This altered layer absorbs laser light that is subsequently irradiated subsequently and is melted and removed, whereby a fine hole can be processed.

If the laser beam used is in a single mode, the laser beam can be narrowed down to the diffraction limit of the light.
The power density can be increased to 0 μm or less,
This is advantageous because the fine holes can be processed more easily and with high precision.

According to the present invention, since a high power density can be obtained at such a low output, the fundamental wave and the second wave can be used even if the laser to be used is not a short wavelength equal to or more than the fourth harmonic as in the prior art.
Using the harmonics or the third harmonic, high quality deep holes without or with few cracks can be formed.

Even in the case of a Q-switched pulsed laser,
In one embodiment, the energy or peak power of one or more pulses initially illuminated by the laser is replaced by the energy of the subsequent pulses, since excessive pulse energy may cause cracks in the workpiece. Alternatively, the power is made smaller than the peak power. Thereby, even if the transparent material cannot be melted / removed by the first one or a series of pulses, the altered layer is formed, and the drilling process can be advanced by fusing / removing this with a later laser pulse. Since it is possible to reduce the thermal stress acting on the surface of the workpiece at the start of processing, the occurrence of cracks is suppressed.

Further, when the laser beam is linearly polarized, cracks tend to occur particularly near the incident portion, and the machining hole tends to bend in the direction of the vibration plane of the magnetic field, so that machining is accelerated in any direction. The hole may be bent and the hole diameter may be enlarged. Therefore, in another embodiment, the laser is irradiated to the surface of the workpiece with circularly polarized light or random polarized light, thereby suppressing bending of a processing hole and enlargement of a hole diameter, and generation of cracks particularly around an incident portion. The processing accuracy and quality are improved.

In one embodiment, a plurality of holes can be simultaneously formed in the surface of the workpiece by irradiating the laser with a phase grating and irradiating the surface of the workpiece, thereby greatly reducing the processing time. be able to.

In still another embodiment, the method further includes a step of pre-heating the workpiece by using an appropriate means, thereby avoiding a rapid rise in temperature inside the workpiece due to laser light irradiation. Cracks can be effectively suppressed by reducing the influence of thermal stress.

In addition, when the light-absorbing substance is uniformly and uniformly deposited on the surface of the workpiece, when processing a large number of holes, a uniform hole can be formed under the same laser conditions. Variation can be prevented.

According to another aspect of the present invention, a Q-switched pulse oscillation laser is irradiated toward a surface of a workpiece made of a transparent material containing a light absorbing substance, and a hole is formed in the surface. A laser processing method for a transparent material is provided.

In this case, since the light absorbing material contained in the surface layer of the workpiece absorbs the laser light, even if the laser has a lower output power than before, the light absorbing substance does not adhere to the surface of the workpiece without causing the light absorbing substance to adhere to the surface of the workpiece. The transparent material of the layer can be melted and removed to form a recess, and the periphery thereof can be transformed into a composition that can more easily absorb laser light. Further, the light absorbing substance and the altered layer contained in the vicinity of the inner wall of the formed recess absorb the laser beam subsequently irradiated and are melted and removed, so that fine drilling can be performed more smoothly. It can be carried out.

The transparent material to which the present invention is applied includes glass or
Is preferably a crystalline material. In particular, Al _TwoO_Three(Alumina)
Glass or soda glass containing more than 20% by weight is convenient
It is. In addition, as the crystal material, lithium niobate,
Lithium tantalate or the like is preferably used.

The laser used in the present invention may be a Q-switch pulse oscillation YAG laser, YLF laser or YV laser.
O lasers are preferred.

[0027]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the accompanying drawings using preferred embodiments. FIG.
1 schematically shows an embodiment of a laser processing apparatus suitable for forming micro holes in glass using the laser processing method of the present invention. This laser processing apparatus includes a laser oscillator 1 having a built-in Q-switch unit for generating a Q-switch pulse oscillation YAG laser, a mirror 2, a condenser lens 3, and an optical path of laser light between the laser oscillator and the mirror. And mechanical shutter means 4 disposed therein. The laser oscillator 1 and the shutter means 4 are electrically connected to a computer 5 for controlling these operations.

Laser light B oscillated from laser oscillator 1
Is reflected by the mirror 2 after passing through the shutter means 4, is condensed by the condenser lens 3, and is irradiated on the workpiece 6. According to the present invention, the laser oscillator 1 outputs a single-mode beam. The single mode beam is excellent in condensing property, the beam spot diameter can be narrowed to 10μm or less, the beam shape is circular, and the power density is concentrated at the center, so a large power density can be obtained with low output, and fine processing Suitable for. The wavelength of the laser beam B is the fundamental wave (1064
μm), but by disposing the nonlinear crystal 7 (for example, LBO) in the optical path between the laser oscillator 1 and the shutter means 4 or inside the laser oscillator, the second harmonic (532
μm) or the third harmonic (355 μm).

The computer 5 outputs a laser oscillation signal having a predetermined pulse width to the laser oscillator 1,
Continuously oscillates a laser beam having a peak output having a magnitude corresponding to the laser oscillation signal. The magnitude of the peak output depends on the length of the standby time. Therefore, the pulse width of the laser oscillation signal output from the computer 5 is determined by the processing conditions such as the depth of a processing hole to be formed. As described above, the Q switch pulse oscillation YAG laser has a low lamp output of about several watts, a large peak output of about several kW or irradiation energy, and has little thermal influence on the workpiece 6. Further, a Q-switch pulse oscillation YLF laser and a YVO laser can be used in the same manner.

As described above, since the magnitude of the peak output depends on the length of the standby time, the peak output of the first pulse of each pulse train becomes excessive. So, computer 5
Outputs a shutter signal to the shutter means 4 in synchronization with the laser oscillation signal and in synchronization with the first pulse of the pulse train, and selectively turns off or passes the laser beam B by the on / off operation. Only the first pulse of the pulse train is cut, and the laser beam controlled to have a constant peak output is continuously pulsed.

FIGS. 2 (a) to 2 (d) show a workpiece 6 by the laser processing method of the present invention using the laser processing apparatus of FIG.
3 shows a process of forming micro holes. In this embodiment, the workpiece 6 is a glass substrate. This glass substrate can be made of various materials including conventionally used hard glass such as soda-lime glass, Pyrex (trademark), lead or crystal glass, crystallized glass, and alkali-free glass, which have been conventionally difficult to laser process. Any suitable glass material may be used.

First, as shown in FIG. 2A, a pigment 8 such as a synthetic resin ink used for a magic ink or the like is coated on the surface of a glass substrate 6 as a light absorbing material by, for example, spin coating to a certain uniform thickness. And apply it. As a light-absorbing substance other than the pigment, a laser beam to be irradiated (wavelength 10
Various known materials such as a coating material that easily absorbs (64 μm) can be used. By making the thickness of the pigment 8 uniform, it is possible to suppress processing variations when processing a plurality of holes in the glass substrate 6, and therefore, the pigment must be a more uniform and high-purity material. Is preferred.

Next, the surface of the glass substrate 6 is focused and irradiated with laser light B. Since the first pulse of the pulse train oscillated from the laser oscillator 1 has an excessive peak, the shutter means 13 is turned on and off by the shutter signal from the computer 5 as described above, and cut, and the peak output of each irradiated pulse is output. Constant. When the first pulse is applied, the pigment 8 in that portion absorbs the laser energy and generates a high-temperature, high-pressure plasma state on the glass substrate surface. Due to this plasma, the surface layer of the glass substrate 6 is partially melted as shown in FIG.
The recess 9 is formed by evaporation or scattering.

A damaged layer 10 is formed on the periphery of the recess 9, such as the opening, the inner wall surface, and the tip. In the deteriorated layer, the peripheral portion of the recess 9 is melted by the high heat of the plasma, and the relatively volatile components contained in the glass material in the portion evaporate first, and the composition changes, and the original material changes. The ratio of the component that easily absorbs the YAG laser, such as alumina, is larger than that of the glass material. Therefore, when the second and subsequent pulses are irradiated, the affected layer 10 absorbs the laser energy and evaporates or scatters, and the processed hole 11 grows as shown in FIG. On the inner wall surface and tip of the processing hole 11,
Similarly, the affected layer 10 is formed. Therefore, by continuing pulse irradiation, a through hole as shown in FIG. 2D is finally completed. Actually, the focusing diameter of the laser is 1
By squeezing to about 0 μm, a through hole having a diameter of about 20 to 30 μm could be formed.

In one embodiment, the glass substrate 6 is preheated to a temperature of, for example, about 200 to 300 ° C. before the irradiation with the laser beam. This avoids a sharp rise in temperature inside the glass substrate during laser light irradiation,
The generation of cracks can be effectively suppressed.

Most of the pigment 8 remaining on the surface of the glass substrate 6 can be washed with a suitable solvent. However, some pigments burn on the glass substrate surface due to the high heat of the irradiation laser and cannot be easily removed with a solvent. In addition, a part of the melt scattered from the processing hole 11 is re-attached to the vicinity of the entrance side and the exit side opening of the processing hole and becomes dross.
Such burn-in and dross of the pigment can be removed by polishing both sides of the glass substrate by a known method after forming the processing hole 11. At the same time, the affected layer remaining on the surface of the glass substrate 6 can be removed by this polishing.

In another embodiment, as shown in FIG. 3, the laser oscillation signals S 1,
S2 is output, and the laser oscillator correspondingly outputs
A pulse YAG laser is output in which the peak output of the first pulse train p1 is smaller than the peak output of the succeeding pulse train p2. As described above, since the peak of the first pulse p11 of the first pulse train p1 becomes excessive, the shutter means 4 is turned on / off by the shutter signal SQ from the computer and cut. In this manner, the surface of the workpiece is first irradiated with three pulses p1 having a small peak output, and thereafter, continuously irradiated with a pulse p2 having a large peak output.

As in the embodiment of FIG. 2, the first pulse train p
When 1 is irradiated, the pigment absorbs the laser energy to generate a high-temperature and high-pressure plasma state on the surface of the workpiece. However, since the irradiation energy is smaller than that in the embodiment of FIG. 2, the workpiece surface layer is only partially melted to form a work-affected layer, and no recess is formed. When a pulse p2 is continuously irradiated thereafter, the laser energy is absorbed by the damaged layer and evaporated or scattered, whereby a processed hole grows as in the embodiment of FIG. Can be completed. In this embodiment, since the initial irradiation energy is reduced, the thermal stress acting on the surface of the workpiece at the start of processing is somewhat reduced, and the generation of cracks is suppressed.

The first pulse p1 having a small peak output
Is not limited to three, and may be one or any number as long as a damaged layer is formed on the surface layer of the workpiece.

In one embodiment, the laser beam is not linearly polarized but is converted into random or circularly polarized light for irradiation. With linearly polarized light, when p-polarized light is incident on the inner wall of the processing hole, the light absorption of the glass material is larger than when the light is incident on the inner wall of the processing hole as s-polarized light. There is a possibility that cracks are likely to be generated near the incident portion, and the processed hole is bent without being formed straight. On the other hand, in the case of the randomly polarized light and the circularly polarized light, the s-polarized light and the p-polarized light are randomly irradiated and there is no deviation of the s-polarized light and the p-polarized light. Therefore, as shown in FIGS. In addition to being formed straight, crack generation near the incident part is suppressed.

In the above embodiment, the fundamental wave (1064)
μm) Q-switched YAG laser was used, but by placing the nonlinear crystal as described above in connection with FIG. 1, the second harmonic (532 μm) or the third harmonic (355
μm) Q-switched YAG laser can be used. Also in this case, a high power density can be obtained with a relatively low output, and by irradiating this with the surface of the workpiece to which the pigment is attached, it is possible to process fine holes in the glass.

In another embodiment, as shown in FIG. 5, a known phase grating 12 is added to the optical path before the condenser lens 3 in the laser processing apparatus of FIG. After passing through the grating, the light can be incident on the condenser lens 3. When the laser beam B passes through the phase grating 12,
One original beam is split into a plurality of beams, and each split beam is condensed by the condenser lens 3 and irradiated onto the surface of the workpiece 6. Therefore, micro holes can be simultaneously formed at a plurality of positions on the surface of the workpiece 6 corresponding to the branch beams, and the processing time is shortened and the productivity is improved.

FIG. 6 schematically shows a process of forming fine holes in a glass substrate by the method according to the second embodiment of the present invention. In this embodiment, the glass substrate 13 is formed of glass having a composition containing a light-absorbing substance that easily absorbs a laser beam to be used. Therefore, it is not necessary to attach a pigment to the surface of the glass substrate 13, and the laser beam B is directly irradiated as shown in FIG. As such a glass, for example, there is neoceram, and alumina, which is a light-absorbing substance, is contained in an amount of about 20% or more.
Contains. In addition, glass such as soda glass,
The present invention can be applied to a transparent material including a crystal such as lithium niobate and lithium tantalate.

The laser used is the same fundamental, second harmonic or third harmonic Q-switched pulse YAG laser used in the first embodiment, and the other processing conditions are exactly the same. When the first pulse is applied, the light absorbing material contained in the surface layer of the portion absorbs the laser energy and generates high heat, whereby the glass of the portion is melted, evaporated or scattered, and FIG. A recess 9 as shown in b) and a damaged layer 10 are formed around the recess 9. The laser beam energy of the second and subsequent pulses is absorbed by the damaged layer 10 and evaporated or scattered.
It grows as shown in (c), and finally a through hole as shown in FIG. 6 (d) is formed.

[0045]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Using a laser processing method according to a first embodiment of the present invention, a type of hard glass, Pyrex.TM.
Was made into a thin plate (thickness: 1 mm) of borosilicate glass commercially available under the trade name No. As a pigment, a synthetic resin ink used in a commercially available magic ink was used, and attached to the surface of a glass thin plate by spin coating. Oscillation frequency 1kHz, average output 400mW, wavelength 5
32μm Q-switched pulse YAG laser, f100mm
Was used. Other processing conditions are as follows.

(Example 1) Laser pulse energy: 400 mJ Irradiation pulse number: 400 / sec (Example 2) Laser pulse energy: 400 mJ Irradiation pulse number: 200 / sec (Example 3) Laser pulse energy: 400 mJ Irradiation pulse number: 300 / sec

In any of the first to third embodiments,
Straight fine holes could be machined in the glass substrate. Further, when the incident surface of the glass substrate was cleaned after processing, the opening of the processing hole was substantially circular, and almost no cracks were observed around the opening. From these results, it is understood that according to the laser processing method of the present invention, high-quality fine holes can be processed at high speed using a low-output laser.

[0048]

Since the present invention is configured as described above, it has the following effects. According to the laser processing method for a transparent material of the present invention, the power density is increased by using a Q-switched pulse oscillation laser having a high light-collecting property, and the light absorption attached to the surface of a workpiece made of a transparent material such as glass. By absorbing laser light into a substance, the laser output can be as low as several watts.
Industrially practical high-quality fine deep holes can be formed at high speed and with high accuracy, and the laser device and processing costs can be reduced.

According to another aspect of the present invention, a laser light is absorbed by a light absorbing material contained in a workpiece made of a transparent material such as glass, similarly using a Q-switched pulsed laser. Fine drilling can be performed more smoothly with low laser output.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a typical example of a laser processing apparatus suitable for carrying out the present invention.

FIGS. 2A to 2D are cross-sectional views schematically showing a process of forming fine holes in a glass substrate by the method according to the first embodiment of the present invention.

FIG. 3 is a diagram showing a laser oscillation signal, an oscillation pulse, a shutter signal, and an irradiation pulse for oscillating laser light in the apparatus of FIG.

FIGS. 4A and 4B are cross-sectional views showing a state of a processed hole when laser light is circularly polarized light and random polarized light, respectively.

FIG. 5 is a schematic diagram showing fine drilling by an optical system using a phase grating.

FIGS. 6A to 6D are cross-sectional views schematically showing a process of forming fine holes in a glass substrate by a method according to a second embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Laser oscillator 2 Mirror 3 Condensing lens 4 Shutter means 5 Computer 6 Workpiece 7 Non-linear crystal 8 Pigment 9 Concave part 10 Degradation layer 11 Processing hole 12 Phase grating 13 Glass substrate

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) C03C 23/00 C03C 23/00 D 5F072 G02B 5/30 G02B 5/30 H01S 3/11 H01S 3/11 // B41J 2 / 135 B41J 3/04 103N F-term (reference) 2C057 AF93 AG12 AP13 AP22 AP23 AP43 AP57 AQ01 2H049 BA03 BA06 BA13 BC21 4E068 AA03 AF01 AF02 AJ03 CA02 CA03 CA04 CD04 CD05 CK01 DA09 DB13 4G015 FA09 FB01 AB02 FC10 AB08 AC30 5F072 AB01 HH07 KK12 QQ02

Claims (15)

[Claims] A light-absorbing substance is attached to the surface of a workpiece made of a transparent material, and a Q-switched pulse oscillation laser is irradiated toward the surface of the workpiece to which the light-absorbing substance is attached, and a hole is formed on the surface. And a laser processing method for a transparent material. 2. The method according to claim 1, wherein the laser beam has a single mode. 3. The laser processing method for a transparent material according to claim 1, wherein a fundamental wave of the laser is used. 4. The laser processing method for a transparent material according to claim 1, wherein a second harmonic of the laser is used. 5. The laser processing method for a transparent material according to claim 1, wherein a third harmonic of the laser is used. 6. The laser processing method for a transparent material according to claim 1, wherein the energy of the first one or more pulses of the laser is smaller than the energy of the subsequent pulses. . 7. The laser processing method for a transparent material according to claim 1, wherein the laser is irradiated with circularly polarized light on the surface of the workpiece. 8. The laser processing method for a transparent material according to claim 1, wherein the laser is irradiated with a randomly polarized light on the surface of the workpiece. 9. The method according to claim 1, wherein the laser beam is split by a phase grating and irradiated on the surface of the workpiece.
9. The laser processing method for a transparent material according to any one of items 1 to 8. 10. The laser processing method for a transparent material according to claim 1, further comprising a step of preheating the workpiece. 11. The laser processing method for a transparent material according to claim 1, wherein the light absorbing substance is attached to the surface of the workpiece in a uniform and uniform thickness. 12. After forming a hole in the surface of the workpiece,
12. The laser processing method for a transparent material according to claim 1, further comprising a step of polishing a peripheral portion of the hole. 13. A laser processing method for a transparent material, comprising irradiating a surface of a workpiece made of a transparent material containing a light absorbing substance with a Q-switch pulse oscillation laser to form a hole in the surface. 14. The laser processing method for a transparent material according to claim 1, wherein the transparent material is glass or a crystal. 15. The Q-switched pulse oscillation laser is
14. A switch pulse oscillation YAG laser, YLF laser or YVO laser.
2. The laser processing method for a transparent material according to item 1.