JP2005239515A - Material to be worked and its forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a working method for a transparent material like glass and the like using a laser beam and taking advantage of a laser beam property. <P>SOLUTION: A glass plate 11 being the transparent material to be worked, a beam absorber 12, another glass plate 13 to press the beam absorber uniformly and a weight 14 are piled on an X-Y stage 10. The transparent material placed on the beam absorber is irradiated with the laser beam 1 from a transparent material side for heating and then a degeneration part is formed at the transparent material. A sacrificing glass plate 15 may be placed between the transparent material and the beam absorber. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a processing method for modifying a transparent material by laser light irradiation. More specifically, the present invention relates to a processing method for forming an altered portion in a transparent material disposed on a light absorber by irradiating a laser beam from the transparent material side.

  Various methods are conventionally known for processing or altering transparent materials such as glass using laser light. For example, as a method in which such processing is applied to the production of an optical waveguide, JP-A-9-311237 and JP-A-11-231151 can be mentioned.

Conventional methods for condensing and modifying these laser beams inside a glass, which is a typical transparent material, can be broadly classified into the following two types.
(1) A method using a pulse laser with a high peak power,
(2) A method of using glass mixed with a light-absorbing substance in order to easily absorb light.

  However, in the above method (1), high peak power is required, and the altered portion is a set of points formed by each pulse. Impossible. On the other hand, in the above method (2), the glass material to be used for irradiation is restricted due to the principle of alteration.

  Therefore, there has been a demand for a method for processing or modifying a transparent material having a higher degree of freedom in processing or alteration (thus, a wider range of application).

JP 9-311237 A Japanese Patent Application Laid-Open No. 11-231151

  An object of the present invention is to provide a processing method capable of eliminating the above-described drawbacks of the prior art.

  Another object of the present invention is to provide a processing method utilizing the characteristics of the laser beam while using the laser beam.

  As a result of earnest research, the present inventor does not alter the transparent material by direct absorption of the laser light by the transparent material as in the past, but utilizes thermal conversion based on laser light irradiation (so-called indirect effect). It has been found that altering transparent materials) is very effective for achieving the above objective.

  The processing method of the present invention is based on the above knowledge. More specifically, the transparent material disposed on the light absorber is irradiated with laser light from the transparent material side, whereby the altered portion is formed on the transparent material. It is characterized by being formed.

  Furthermore, according to the present invention, a processed material including at least a transparent material and an altered portion formed in the transparent material, wherein the altered portion and the unaltered portion are different in refractive index, A processing material is provided that is distinguishable by at least one characteristic among the differences in the etching rate.

  The present invention includes the following embodiments, for example.

  (1) A processing method characterized in that an altered portion is formed in the transparent material by irradiating the transparent material disposed on the light absorber with laser light from the transparent material side.

  (2) The process material forming method according to (1), wherein the altered portion is caused by local heating based on laser light.

  (3) The processing method according to (1) or (2), wherein the transparent material is a glass material.

  (4) The processing method according to any one of (1) to (3), wherein a surface of the light absorber is made of metal.

  (5) The processing method according to any one of (1) to (4), in which another material is disposed between the light absorber and the transparent material.

(6) A processed material comprising at least a transparent material and an altered portion formed in the transparent material,
A processed material characterized in that the altered portion and the unaltered portion can be distinguished by at least one characteristic among a difference in refractive index and a difference in etching rate.

  (7) The processed material according to (6), wherein the altered portion has a columnar shape, and the aspect ratio of the altered portion is 5 or more.

  (8) The processed material according to (6) or (7), wherein the altered portion is cylindrical.

  (9) The processed material according to any one of (6) to (8), wherein the altered portion is removed by etching.

  In the method disclosed in Japanese Patent Laid-Open No. 9-311237 described above, pulsed laser light having a high peak value, such as a femtosecond laser, is condensed inside the glass, thereby causing alteration within the glass. On the other hand, in the present invention, an absorber is disposed on the surface opposite to the laser incident side, and the laser is irradiated from the transparent material (glass etc.) side, thereby altering the inside of the transparent material. The part is produced. According to the present invention, for example, it is easy to use a continuous wave laser beam.

  According to the present invention having the above-described configuration, there is provided a method for processing or altering a transparent material having a higher degree of freedom in processing or alteration (and hence a wider range of application).

Hereinafter, the present invention will be described more specifically with reference to the drawings as necessary. In the following description, “parts” and “%” representing the quantity ratio are based on mass unless otherwise specified.
(Laser light)
The laser beam to be used in the present invention is a transparent material disposed on the light absorber by light-to-heat conversion based on the irradiation when the laser beam is irradiated to the light absorber through a transparent material. As long as it is possible to heat (i.e., to be absorbed by the light absorber and heat the transparent material), there is no particular limitation. In the present invention, the “transparent material disposed on the light absorber” means that the transparent material is disposed at a position where it can be heated by light-to-heat conversion based on laser irradiation. Therefore, as long as the heating is possible, a third material (for example, a sacrificial material described later) may be sandwiched between the light absorber and the transparent material.

In the present invention, the altered portion can be formed even when a continuous-wave laser having a relatively low cost is used, particularly in comparison with a pulse laser. In this way, when a continuous wave laser beam is used, a deteriorated portion having excellent continuity can be obtained more easily than when a pulse laser is used.
(Suitable laser light)
Examples of laser light that can be suitably used in the present invention include the following.

Laser light type: Argon ion laser,,,
Wavelength: 400-1300 nm (more preferably 460-600 nm)
Output: 4-20W, more preferably 10-20W
(Processing method)
In the processing method of the present invention, the transparent material disposed on the light absorber is irradiated with laser light from the transparent material side, and an altered portion is formed in the transparent material based on local heating based on the irradiation. . According to the knowledge of the present inventor, when a light absorber that absorbs laser light is installed on the side opposite to the laser incident side, and when the light absorber is locally heated by the laser light, It is presumed that the absorption coefficient of glass changes due to heat heating the glass and is based on absorbing laser light. For example, an altered layer can be formed inside the glass by causing this phenomenon continuously.
(Light absorber)
The light absorber to be used in the present invention is to heat a transparent material disposed on the light absorber by light-to-heat conversion based on laser light irradiation (that is, to absorb the laser light, It is not particularly limited as long as it can be heated. That is, as the light absorber, the following various substances or materials can be used.

As long as it has the above-mentioned characteristics, the light absorber to be used in the present invention is formed by, for example, applying a pigment layer (for example, an oil-based ink such as so-called “magic ink”) to a transparent material on which an altered portion is to be formed. It may also be a dye layer.
(Suitable light absorber)
The light absorber that can be suitably used in the present invention preferably further has the following characteristics.
(1) Low reflectivity of laser light More specifically, the reflectivity of laser light to be used in the present invention is preferably 65% or less, and more preferably 50% or less. The reflectance of this laser beam can be measured by the following method, for example.
<Measurement method of laser light reflectance>
Measured under the following conditions with a UV-visible spectrophotometer V-570 (optional: horizontal sample-type integrating sphere device) manufactured by JASCO Corporation.
Wavelength: The wavelength of the laser used for alteration (488nm in this example)
Response: slow
Band width: 40nm
For example, a laser beam having a high reflectance (for example, an aluminum foil: 80% reflectance) does not deteriorate, but a laser beam having a low reflectance (for example, a copper foil: 50% reflectance) can be altered.
(2) Low thermal conductivity.

More specifically, the light absorber that can be suitably used in the present invention preferably has a thermal conductivity of 4 W / cm ° C. or less, and more preferably 0.4 W / cm ° C. or less. The thermal conductivity of this light absorber can be measured, for example, by the following method.
<Measurement method of thermal conductivity>
Measured under the following conditions using a hot disk method thermophysical property measuring apparatus TPA-501, manufactured by Kyoto Electronics Industry Co., Ltd.
Temperature: 30 ° C
(3) The laser beam does not easily make a hole in the light absorber In the present invention, the laser beam to be used means that the light absorber does not easily make a hole, for example, as follows. Can be confirmed.
<How to check the degree of hole opening with laser light>
Using an argon ion laser (Coherent TSM-20), the laser beam 1 is focused by a plano-convex lens with a focal length of 170 mm (Sigma Koki Co., Ltd., plano-convex lens SLSQ-30-170PAI) (not shown). Then, the absorber 2 is irradiated. The laser output is 20W (see Fig. 12). Focus on the surface. Install the beam detector 3 (manufactured by OFIR JAPAN Co., Ltd., thermopile surface absorption head 30A) immediately after the absorbent, and after 3 seconds of irradiation, the detector displays 10W or less.
(Transparent material)
The transparent material to be used in the present invention is not particularly limited as long as it is a transparent material that can be heated by the combination of the laser beam and the light absorber. Examples of the transparent material that can be used in the present invention include the following. For details on the effects of laser irradiation when glass is used as the transparent material, see, for example, Kiyotaka Miura and Kazuyuki Hirao, “Photo-induced refractive index change inside glass by ultrashort pulse laser”, Laser Research, 26, No. 2 (February 1998), p. 150; Hiroshi Kumagai, “Femtosecond Laser Processing”, Applied Physics, Vol. 67, No. 9 (1998).
Glass (for example, soda glass, quartz glass, borosilicate glass, fluoride glass, chalcogenide glass)
Resin (eg acrylic resin, vinyl chloride)
Crystal materials (sapphire, silicon, gallium arsenide, calcium fluoride, zinc selenium, sapphire, germanium, barium fluoride, lithium fluoride, magnesium fluoride, etc.)
The transparent material that can be suitably used in the present invention preferably further has the following characteristics.
(1) The laser beam absorbency is low.

  More specifically, the absorptivity of the laser beam to be used is preferably 80% or more (when the thickness is 10 mm), and more preferably 90% or more.

The absorptance of this laser beam can be measured, for example, as follows.
<Measurement method of laser light absorption rate>
An argon ion laser (TSM-20 manufactured by Coherent) is used to irradiate the transparent material 2 with the laser beam 1. The laser output is 20W. Immediately after the transparent material, a beam detector 3 (manufactured by OFIR JAPAN Co., Ltd., thermopile surface absorption head 30A) is installed, and the intensity of the transmitted laser light is measured (see FIG. 13).
Material thickness: 10mm
(2) The laser light absorption rate is likely to change due to temperature change. From the point that the laser light absorption rate is likely to change, for example, the laser light absorption rate A ₂₅ at room temperature (25 ° C.) and the higher temperature of 750 ° C. the ratio of the absorptance _{a H} of the laser beam _(a H _{/ a 25)} is in, is preferably 1.1 or more, further preferably 1.2 or more (in particular 1.4 or higher).
<Measurement method>
An argon ion laser (TSM-20 manufactured by Coherent) is used to irradiate the transparent material 2 with the laser beam 1. The laser output is 20W. The transparent material is installed in the furnace 4 (see FIG. 14). A beam detector 3 (manufactured by OFIR JAPAN Co., Ltd., Thermopile surface absorption head 30A) is installed after the transparent material, and the intensity of the transmitted laser light is measured to calculate the absorption rate. Find the ratio to high temperature (750 ° C).
Material thickness: 10mm
(3) Excellent heat resistance.

  If the heat resistance is relatively low, troubles such as cracking of the transparent material are likely to occur due to heat generated by laser light irradiation.

More specifically, this heat resistance can be measured by, for example, the coefficient of thermal expansion. That is, the transparent material that can be suitably used in the present invention preferably has a coefficient of thermal expansion of 80 × 10 ⁻⁷ K ⁻¹ or less, and more preferably 40 × 10 ⁻⁷ K ⁻¹ or less.

For example, soda glass (thermal expansion coefficient 99 × 10 ⁻⁷ K ⁻¹ ) has a relatively strong tendency to crack, but borosilicate glass (thermal expansion coefficient 32 × 10 ⁻⁷ K ⁻¹ ) has a considerable tendency to crack. The inventor has found that it is small (almost never cracked). For the specific value of the coefficient of thermal expansion or the details of the measuring method, reference can be made to, for example, Asakura Shoten edited by Sakuo Hana, “Glass Dictionary”.
(Transparent material size, etc.)
The size of the transparent material to be used in the present invention is not particularly limited as long as it can be heated by the combination of the laser beam and the light absorber. The size and the like of the transparent material that can be suitably used are as follows.

Thickness: 0.1-20mm (further 0.1-3mm)
Size: 0.1 x 0.1 cm or more (further 0.2 x 0.3 cm or more)
(Changed part)
According to the present invention, it is easy to form the altered portion in the transparent material (glass or the like) on the substantially same axis as the laser beam by laser beam irradiation. In the present invention, the size (diameter, length), number, direction, etc. of the altered portion are not particularly limited. From the viewpoint of application as an optical waveguide, the size of the altered portion as described below is suitable.

Diameter: 0.3 μm to 0.1 mm (further 1 μm to 0.01 mm)
According to the present invention, for example, an altered portion can be formed inside a transparent material with a continuous wave laser having an output of several tens of watts. In this case, for example, an altered portion having a diameter of about 30 μm can be formed at a speed of about 50 mm / s.
(Control method of altered part)
In the present invention, the thickness, length, etc. of the altered portion can be changed by changing the laser output, laser diameter, scanning state, etc., for example. According to the experiment of the present invention, as will be described later, the thickness of the altered portion can be changed from 30 to 120 μm (see the graph of FIG. 10), and by changing the defocusing distance, The length can be changed (see graph of FIG. 11).

Further, the altered portion in the present invention changes the transparent material through a state (that is, an altered portion that gives a through hole after etching) by changing, for example, the laser output, the laser diameter, the scanning state, and the like. It can also be in a non-penetrating state (that is, an altered portion that provides a non-penetrating hole after etching).
(aspect ratio)
According to the present invention, it is easy to form a relatively deep altered portion in a relatively narrow range. According to the experiment of the present inventor, for example, an altered portion having a length of L = 10 mm (aspect ratio = L / d = 125) is possible in the range of the maximum diameter d = φ80 μm. Here, the “aspect ratio” refers to the ratio between the length and the diameter of the altered portion.

In other words, according to the present invention, for example, an altered portion having an aspect ratio of 5 or more, further 10 or more, and particularly 30 or more can be easily formed.
(Etching rate measurement)
The altered portion inside the glass produced by the present invention can be clearly identified, for example, by subjecting it to an etching process. For example, as shown in FIGS. 7 to 9 to be described later, when borosilicate glass and quartz glass processed (modified) by the method of the present invention are etched under the following conditions, the difference in etching amount between the modified portion and the non-modified portion is caused. About 30 nm / min was obtained with borosilicate glass, and about 5.8 nm / min was obtained with quartz glass. That is, according to the method of the present invention, the difference (Q−P) between the etching rate P of the altered portion and the etching rate Q of the unaltered portion is 10 nm / s (in the case of borosilicate glass) or 2 nm / s ( In the case of quartz glass, it is possible to easily form an altered portion as described above.

From another point of view, the ratio (Q / P) of the etching rate Q of the altered portion and the etching rate P of the non-altered portion is 1.1 or more, further 1.3 or more (particularly 1.4 or more). Such an altered portion can be easily formed (according to the experiment of the present inventor described later, for example, Q / P = 1.49 is obtained).
<Etching conditions>
Etching solution HF: H ₂ O: HNO ₃ = 15: 300: 10 (weight ratio)
Temperature: Room temperature (20-25 ° C)
In this way, the altered portion has a higher etching rate and is removed faster than the unaffected portion. Therefore, it can be applied to drilling described later by immersing in an etching solution. Further, since the altered portion has a high refractive index of light, it can be used as an optical waveguide as will be described later for optical fiber demultiplexing, a mixer, and the like.
(Preferred embodiment)
Fig.1 (a) is a schematic cross section which shows the one aspect | mode of the apparatus which can be used conveniently for the processing method according to this invention. Referring to FIG. 1A, on a XY stage 10 (from the incident side (lower side) of the laser beam 1) (1) a glass plate 11 to be processed (an example of a transparent material; 3 types of glass used, ie, one of soda, pyrex, or quartz glass); (2) copper foil 12 (light absorber), (3) another for holding the copper foil uniformly A glass plate 13 and (4) a weight 14 for applying a load were sequentially stacked. The copper foil is selected in consideration of the laser absorption rate. In this example, for the purpose of processing from the side opposite to the incident side of the glass plate 11 with the laser beam 1 transmitted through the glass plate 11, a laser beam having a wavelength with high glass transmittance is used. In this embodiment, for example, a continuous wave argon ion laser (TSM-20 manufactured by Coherent) can be used for heating. The laser beam 1 was spread by a triple beam expander (not shown), then condensed by a plano-convex lens (not shown) having a focal length of 170 mm and irradiated onto the glass plate 11. The focus was adjusted to the surface of the metal foil. The entire glass plate 11, copper foil 12, other glass plate 13 and weight 14 are moved by the XY stage 10 to scan the laser beam 1 in a desired manner.

  By irradiating a laser beam 1 onto a glass plate 11 on which a metal foil 12 is placed as shown in FIG. 1A, a deteriorated layer can be formed inside the glass plate 11 as shown in an example described later. . According to the knowledge of the present inventor, such a deteriorated layer is formed by locally heating the metal foil 12 by the laser beam 1 and heating the glass plate 11 in the vicinity of the metal foil 12 by the heat thus generated. Thus, the absorptance changes and the glass plate 11 absorbs the laser light 1, and as a result, it is presumed that an altered layer is formed inside the glass plate 11.

By irradiating the glass plate 11 on which the metal foil 12 is placed with the laser beam 1 in this way, a deteriorated layer having a thickness of, for example, about 30 μm can be formed inside the glass plate 11.
(Other aspects)
FIG.1 (b) is a schematic cross section which shows the other aspect of the apparatus which can be used conveniently for the processing method according to this invention. With reference to FIG.1 (b), in this aspect, it shows to Fig.1 (a) except having arrange | positioned the sacrificial glass plate 15 between the glass plate 11 which is a process target, and the copper foil 12. FIG. This is the same as the embodiment. By arranging the sacrificial glass plate 15 in this way, it becomes easy to suppress undesirable modification (for example, generation of cracks) of the glass plate 11 to be processed.
(Application examples)
The method of the present invention can be applied without particular limitation to decorations such as optical switches as optical waveguides. An example of an optical waveguide that can be formed according to the present invention is shown in the schematic plan view of FIG. 2. The present invention will be described more specifically with reference to examples.

Example 1
Referring to FIG. 1A, on an XY stage 10 (manufactured by Sigma Koki Co., Ltd., trade name: STM-50XY) (from the incident side (lower side) of the laser beam 1) (1) Glass plate 11 to be processed (one kind of soda, Pyrex, or quartz glass); (2) Copper foil 12 (light absorber), (3) Another glass plate 13 for uniformly holding the copper foil And (4) a weight 14 for applying a load was sequentially stacked. The copper foil 12 was selected in consideration of the laser absorption rate. Both ends of the glass plate 11 were placed on the XY stage 10 by about 7 mm.

  In this example, laser light having a wavelength with high transmittance of glass was used for the purpose of processing from the side opposite to the incident side of the glass plate 11 with the laser light 1 transmitted through the glass 11. A continuous wave argon ion laser (TSM-20 manufactured by Coherent) was used for heating, and this laser beam 1 was tripled by a beam expander (not shown; manufactured by Sigma Koki Co., Ltd., trade name: After spreading with a laser expander (LBE-3), the glass plate 11 is focused with a plano-convex lens (not shown; product name: plano-convex lens SLSQ-30-170PAI, not shown; Sigma Koki Co., Ltd.) with a focal length of 170 mm. did. The focus was adjusted to the surface of the metal foil. The whole of the glass plate 11, the copper foil 12, the other glass plate 13 and the weight 14 described above was moved by the XY stage 10, thereby scanning the laser beam 1 in a desired manner.

  The experimental conditions used here are as follows.

Laser: Argon ion laser,
Wavelength: 455-529 nm (multiline)
Output: 5-20w
Scanning speed: 500 μm / s
Focal length: 170mm
Glass to be processed (both sizes are 3cm x 3cm):
Soda glass (Asahi Glass Co., Ltd.)
Silica glass (Toshiba Ceramics Co., Ltd., trade name: T-4040)
Borosilicate glass (Corning Japan, trade name: 7740)
Glass thickness: 2mm
Metal foil: Copper foil (thickness 10μm)
Uniform presser glass: Borosilicate glass (thickness 2 mm, size 3 cm x 3 cm)
The result of the laser irradiation is shown in the optical micrograph (magnification: 1250 times) in FIG. Altered portions were observed at the same position on the upper surface (FIG. 3 (a)) and the lower surface (FIG. 3 (b)), and an altered layer was observed in the form of dots in spite of scanning with laser light. . Cracks were observed on the upper surface (FIG. 3A; the surface in contact with the copper foil 12 side). As will be described later, when the copper foil 12 is not placed on the glass plate 11, no crack was observed (see Comparative Example 1 described later). Probably caused by heating.

On the lower surface (FIG. 3B), an altered portion having a diameter of about 30 μm was observed, and fibrous deposits were observed around it. When the microscope was focused on the inside of the glass and observed, this altered portion was connected along the optical path of the laser beam from the top surface to the bottom surface. Moreover, the optical microscope photograph of the metal foil of the surface which was in contact with the processed glass plate 11 is shown in FIG. Corresponding to the part where the glass has been altered, a point-discolored part is observed.
Example 2
(When sandwiching the sacrificial glass)
With reference to FIG.1 (b), in this example, except having put the glass plate 15 used as a sacrifice between the glass plate 11 and the metal foil 12 to be processed, the material is the same as in Example 1. Again, laser irradiation was performed in the same manner.

  The observation results from the upper surface, cross section, and lower surface of the glass plate 11 to be processed obtained as described above are shown in FIGS. 5A, 5B, and 5C, respectively.

From FIG. 5A, no crack was observed on the upper surface of the glass, and the formation of cracks in the glass 11 to be processed could be prevented by sandwiching the sacrificial glass plate 15. Further, it can be seen from FIG. 5B that the altered portion inside the glass is formed from the upper surface to the lower surface. This altered layer had a diameter of about φ30 μm. Moreover, when the sacrificial glass plate 15 was observed, alteration was recognized at the same position as the altered portion of the glass plate 11 to be processed. From this, it was considered that this altered portion was transmitted from the sacrificial glass plate 15 to the glass plate 11 (1) to be processed. Thus, the formation of cracks could be prevented by stacking two pieces of glass (the glass plate 11 and the sacrificial glass plate 15 to be processed).
Comparative Example 1
(Irradiation to glass only)
Without placing the copper foil 12, only the glass plate 11 to be processed was placed on the XY stage in the same manner as in the configuration of FIG.

  When borosilicate glass or quartz glass was used as the glass plate 11 to be processed, no change was observed, but with soda glass, a change was observed when the laser output was 20 W.

FIGS. 6A and 6B show optical micrographs of the upper and lower surfaces (laser incident side) of the soda glass portion where the change was observed, respectively. The arrow in the figure indicates the laser scanning direction, and the back side of the circle in FIG. 6B is the position in FIG. Further, even when a change was observed on the lower surface of the glass, an altered portion as shown in FIG. 6A was not always recognized on the upper surface. The change on the upper and lower surfaces occurred very rarely, and it is thought that it started to absorb the dust adhering to the glass.
Example 3
(Etching process)
The processing target glass plate 11 (glass thickness 0.2 mm, quartz glass) having an altered portion obtained in the same manner as in the above example was further subjected to an etching treatment. The altered portion has a higher etching rate than the non-altered portion, and is removed faster by etching. Therefore, for example, the altered portion was removed, and it could be applied to drilling as shown in a scanning electron microscope (SEM) photograph (magnification: 500 times, voltage 25 kV) in FIG. Here, as the SEM described above, product name S-2400 manufactured by Hitachi High-Technologies Corporation was used. The etching conditions used in this example are as follows.
<Etching conditions>
Etching solution HF: H ₂ O: HNO ₃ = 15: 300: 10 (weight ratio)
Temperature: 20-25 ° C
Etching time: 9 hours
Example 4
(Etching process with varying time)
Etching was performed in the same manner as in Example 3 except that the etching time was changed between 0 and 230 minutes.

The obtained results are shown in the graphs of FIGS. Etching of borosilicate glass and quartz glass (etching time 230 minutes) results in a difference in etching amount between the altered portion and the unaltered portion, resulting in about 30 nm / min for borosilicate glass and about 5.8 nm / min for quartz glass. It was.
Example 5
(Change in laser output)
Laser processing was performed in the same manner as in the above example except that the laser output was changed between 5 and 22 watts.

The obtained results are shown in the graph of FIG. As shown in FIG. 10, the thickness of the altered portion was a diameter of φ20 μm to φ150 μm.
Example 6
(Change in defocus distance)
Laser processing was performed in the same manner as in the above example except that the defocusing distance was changed between −10 and +10 mm.

  The obtained results are shown in the graph of FIG. As shown in FIG. 11, it was possible to change the length of the altered portion.

It is a schematic cross section which shows the example of the apparatus system which can implement suitably the laser processing method of this invention. It is a schematic plan view which shows an example of the optical waveguide which can be formed with the processing method of this invention. Optical micrographs showing the upper surface (a) and the lower surface (b) of the laser processed glass obtained in the examples (borosilicate glass (without sacrificial glass), laser output: 20 W, scanning speed: 0.5 mm / s, magnification: 1250 times). It is an optical microscope photograph (Laser output: 20 W, scanning speed: 0.5 mm / s, magnification: 500 times) which shows the copper foil surface obtained after laser irradiation in an Example. It is an optical microscope photograph (magnification: 50 times) which shows the upper surface (a), the cross section (b), and the lower surface (c) of the laser processing glass (pyrex) obtained in the Example (laser output: 20 W, scanning speed: 0). .5 mm / s). It is the optical microscope photograph (magnification: 250 times) which shows the upper surface (a) (magnification: 1250 times) and the lower surface (b) of the laser processing glass (soda glass) obtained by the comparative example (laser output: 20W, scanning) Speed: 0.5 mm / s). It is a scanning electron micrograph (magnification: 500 times) which shows the hole of the processing glass (quartz glass) obtained by the etching process in the Example. It is a graph which shows the difference of the etching amount of a modified part and a non-altered part in the process borosilicate glass obtained by changing etching time in an Example. It is a graph which shows the difference of the etching amount of the modified | denatured part and non-altered part in the processing quartz glass obtained by changing etching time in an Example. It is a graph which shows an example of the relationship between the diameter of the quality-change part in the process target glass obtained by changing a laser output in an Example, and a laser output. It is a graph which shows an example of the relationship between the length of the quality-changed part in the processing object glass obtained by changing the defocus distance in an Example, and a defocus distance. It is a schematic cross section which shows an example of the confirmation method of the hole opening by a laser. It is a schematic cross section which shows an example of the measuring method of a laser absorptivity. It is a schematic cross section which shows an example of the measuring method of the temperature change of a laser beam absorptance.

Claims (9)

  A processing method characterized by forming an altered portion in a transparent material disposed on a light absorber by irradiating the transparent material with laser light from the transparent material side.   The process material forming method according to claim 1, wherein the altered portion is caused by local heating based on laser light.   The processing method according to claim 1, wherein the transparent material is a glass material.   The processing method according to claim 1, wherein a surface of the light absorber is made of a metal.   The processing method according to any one of claims 1 to 4, wherein another material is disposed between the light absorber and the transparent material. A processed material comprising at least a transparent material and an altered portion formed in the transparent material,
A processed material characterized in that the altered portion and the unaltered portion can be distinguished by at least one characteristic among a difference in refractive index and a difference in etching rate.   The processed material according to claim 6, wherein the altered portion has a columnar shape, and the aspect ratio of the altered portion is 5 or more.   The processed material according to claim 6 or 7, wherein the altered portion has a cylindrical shape. The processed material according to claim 6, wherein the altered portion is removed by etching.