JP5633070B2 - Flowable materials used in laser-induced backside transparent substrate microfabrication - Google Patents

Description

  The present invention relates to a fluid material used in laser micromachining, particularly laser-induced backside transparent substrate micromachining.

Conventionally, for example, the following methods are known as fine surface processing methods for quartz glass, which is a transparent substrate.
(1) Multi-step lithography method After forming an appropriate resist on the substrate surface, patterning is performed by lithography, etching is performed using an ion beam, plasma, or hydrofluoric acid, and then the resist is further stripped ( JP-A-6-280060).
(2) Ion etching method A method of performing maskless chemical etching utilizing the difference in etching rate produced by the ion implantation method (Japanese Patent Laid-Open No. 7-256473).
(3) Short wavelength laser method A dry etching method using a laser that oscillates short wavelength light that can be absorbed by a transparent material (Japanese Patent Laid-Open No. 7-256473).
(4) Ultrashort pulse laser method A dry etching method using an ultrashort pulse laser having a pulse width of picosecond or less (Varel et al .: Appl. Phys. A, vol. 65, p. 367, (1997)).
(5) Laser Induced Plasma Method A method in which a metal substrate is placed behind a glass, irradiated with a laser, and plasma generated from the metal is used (Japanese Patent No. 3401425).
(6) Method of generating a component having a high laser absorptance A method of irradiating a workpiece made of a glass surface layer in which a component having a high laser absorptivity is generated in advance (Japanese Patent Laid-Open No. 2000-61667).
(7) A method of performing laser processing after forming a light absorption layer such as a pigment on the glass substrate surface. A light absorption layer such as a pigment is formed on and attached to the glass substrate surface, and a laser is irradiated toward the surface. A method in which a light absorption layer absorbs laser energy to generate a high-temperature and high-pressure plasma state on the glass substrate surface, and the glass on the surface layer is melted and removed (Japanese Patent Laid-Open No. 2000-301372, Japanese Patent No. 3001816, JP-A-60-257985).

However, since the method (1) is based on the photolithography technique, a number of complicated steps such as resist coating, drying, exposure, development, etching, and stripping are required, and the fine processing is required. There is a problem that time efficiency is low.
The method (2) requires an ion implantation apparatus that can collect light, and has a problem that it is not suitable for mass production because the processable range is small and the time efficiency is low.
The methods (3) and (4) require a high vacuum environment, have poor energy efficiency, and are not suitable for mass production.
In the method (5), there is a problem that processing cannot be performed unless a vacuum atmosphere is used or the metal substrate and glass are brought into close contact with each other.
In the method (6), since it is essential to generate a component having a high laser absorptance, there is a problem that a processing material cannot be freely selected.
In the method (7), there is a problem in that the step of removing the light absorption layer that has not been processed is necessary, and the time efficiency is low.

Against this backdrop, the present inventor, together with the other inventors, directly puts the laser-absorbing fluid substance injected into the cell on the back surface of the transparent material as shown in Patent Document 1 below. A processing method in which a laser beam is irradiated from the surface of a transparent material, that is, a laser-induced back-side transparent substrate fine processing method is proposed. In this processing method, a laser beam with an intensity range of 0.01 J / cm ² / pulse to 100 J / cm ² / pulse is irradiated from the surface of the transparent material, and the laser beam is condensed on the back surface thereof. It has been proposed to perform predetermined microfabrication on the back surface of a transparent material by etching the surface of glass using a laser-induced photothermal reaction that occurs when a fluid substance absorbs a laser beam in the light portion.

  Such a laser-induced photothermal reaction is known to cause a rapid increase in temperature and pressure in the condensing part of the laser beam. In Non-Patent Document 1 below, the temperature rises due to the absorption of the laser beam and is 2000 degrees. Non-Patent Document 2 reports that the pressure immediately after laser beam absorption is 10 to 200 MPa.

  Further, as a related invention, in Patent Document 2 below, the laser condensing position is controlled using position measurement data, and in Patent Document 3, a reference plate that directly regulates the back surface position of the transparent material is provided. The transparent material is sandwiched between the first holder plate and the cell containing the fluid substance is pressed and fixed by the second holder plate on the back surface of the transparent material. After forming the film, an organic thin film patterned on the transparent substrate is irradiated by irradiating a laser beam from the opposite side of the organic thin film on the transparent substrate in contact with a fluid substance having strong absorption at the laser wavelength. And simultaneously forming an etching on a transparent substrate.

Japanese Patent No. 3012926 Japanese Patent No. 4565114 Japanese Patent No. 4231924 Japanese Patent No. 4214233

Wang et al .: Appl. Phys. A, vol. 68, p. 111, (1999) Kawaguchi et al .: Appl. Phys. A, vol. 79, p. 883 (2004)

  Such a laser-induced backside transparent substrate microfabrication method is sufficient with a laser intensity of about one tenth of an energy compared to the conventional method using ultraviolet light, and does not require a vacuum atmosphere. Moreover, it is revolutionary in that it enables precise and fine etching of a transparent material continuously in one step, but it is necessary for the laser beam to pass through a transparent material such as glass and reach a fluid substance. Therefore, when the light transmittance of the transparent material is low, there is a problem that the incident surface is damaged before the back surface processing occurs, and the intensity of the laser beam cannot be increased excessively. There is a limit.

In addition, even when the transmittance is high, even if the laser beam intensity is increased to increase the processing efficiency, the temperature and pressure rise of the fluid substance is not stable in the condensing part on the back surface of the transparent material, and it is not processed. A part remained, and processing accuracy might be lowered. The occurrence of such an unprocessed portion deteriorates the processing quality, for example, when the marking is performed on the glass material, the marking content cannot be read. Further, in order to avoid this, the unprocessed portion can be apparently reduced by repeating many beam scans of the same location, but in that case, processing will take time, Since non-uniformity occurs in the processing depth, it becomes a problem when the processing groove is used as a micro flow path.
Therefore, the present invention reduces the energy value required for processing on the back surface in such a laser-induced back surface transparent substrate fine processing method, and prevents processing accuracy from being lowered due to unprocessed portions while increasing processing efficiency. The purpose is that.

In order to achieve such an object, the inventor pays attention to the flowable substance in the cell existing on the back surface of the glass, and by increasing the heat generation efficiency at the time of condensing the laser, the inventor can efficiently use a low-intensity laser beam. Realized highly accurate machining.
Here, in the above-mentioned Patent Documents 1 and 2, regarding the fluid substance in the cell, an acetone solution of pyrene, an acetone solution of benzyl, a tetrahydrofuran solution of pyrene, an ethanol solution of rhodamine 6G, an ethanol solution of phthalocyanine, etc. Examples thereof include a solution of an organic compound containing an aromatic ring, a solution containing an organic dye compound, and a liquid compound such as benzene, toluene and carbon tetrachloride. Also, a solution made by dispersing organic compounds, organic dyes, inorganic pigments, or fine particles of carbon, etc., or a fluid powder made of fine particles or fine crystals of organic compounds, organic dyes, inorganic pigments, or carbon powders. The body is listed.

These fluid substances need to have a high absorption rate with respect to the wavelength of the laser beam used. Therefore, a fluid substance is dissolved into a laser beam-absorbing substance (dye, pyrene, benzyl, rhodamine 6G, etc.) that has high absorption at a specific laser beam wavelength, and the substance has a high concentration (for example, 0.1 moldm). ^-3 or higher concentration), which is a liquid substance soluble in a solvent (acetone, tetrahydrofuran, ethanol, etc.). In the present invention, the function of absorbing the laser beam itself, or a laser absorbing substance. Does not have the function of dissolving a large amount of water, but reacts with the occurrence of high-temperature and high-pressure conditions of a fluid substance produced by absorption of a laser beam, and additionally generates heat or pressure, or generates a reaction. Processing acceleration that promotes processing efficiency and processing accuracy by creating a source of additional heat and pressure by attaching objects to the glass By adding a substance, the processing efficiency and processing accuracy at the time of laser beam focusing were increased.

Specifically, the flowable material used in the laser-induced backside transparent substrate microfabrication of the present invention is configured as follows.
(1) The laser beam that has passed through the transparent material is condensed on the back surface thereof, and the flowable substance that contacts the back surface of the transparent material absorbs the laser beam at the condensing point, and the temperature rises to near the melting point of the transparent material. And a flowable material used for laser-induced back-type transparent substrate microfabrication for etching the transparent material at the condensing point by generating a high pressure, the laser beam absorbing material, and In addition to a solvent that dissolves the substance at a high concentration to form a fluid substance , it has an absorption region in a short wavelength range with respect to the wavelength of the laser beam , and itself has absorption characteristics for the laser beam. However, a processing promoting substance that decomposes with the heat generation of the laser beam absorbing material and improves processing accuracy and processing speed was added.

(2) In the fluid substance of the above (1), water-soluble substances such as edible yellow No. 4 dye, edible yellow No. 5 dye, edible red No. 104 dye, red 213 dye, green No. 401 dye as the laser beam absorbing substance. At least one of the organic dyes was used, water was used as the solvent, and benzene derivative organic acid salts such as paratoluenesulfonic acid sodium salt and benzoic acid sodium salt were added as the processing accelerator.

(3) In the fluid substance of (2) above, when edible yellow No. 5 dye is used as the laser beam absorbing substance, 0.01 to 1.0 g of paratoluene per 1 mL of a saturated aqueous solution of edible yellow No. 5 dye Sulfonic acid sodium salt was added as the processing accelerator.

(4) In the fluid substance of (2) above, when the laser beam absorbing substance uses edible yellow No. 5 dye, 0.01 to 1.0 g of sodium benzoate per mL of saturated aqueous solution of edible yellow No. 5 dye Salt was added as the processing accelerator.

(5) In the fluid substance of (1) above, at least one of dyes soluble in an organic solvent such as edible red No. 105 dye, red No. 213 dye, rhodamine 6G dye is used as the laser beam absorbing substance, Ethanol was used as the solvent, and an aromatic compound derivative having no absorption region at the wavelength of the irradiated laser beam, such as toluene or benzene, was added as a processing accelerator.

(6) In the fluid substance of the above (5), when rhodamine 6G dye is used as the laser beam absorbing substance, toluene is used as the processing promoting substance, and the toluene is 0.1 to 0.1 by volume with respect to ethanol. 3 to obtain a saturated solution of the rhodamine 6G dye mixture.

  According to the present invention, in addition to the laser beam absorbing material and the solvent that dissolves the material in a high concentration to form a fluid material, the laser beam absorbing material does not have absorption characteristics with respect to the laser beam itself. As a processing accelerator that adds heat and pressure is decomposed to generate heat and pressure, the processing threshold for the required laser beam intensity is lowered and processing with a lower intensity laser beam is possible. In both cases, when the same laser beam intensity is used, it is possible to increase the processing efficiency as compared with the conventional fluid substance and to realize stable processing with suppressed generation of unprocessed portions.

1 is an overall view of a laser-induced backside processing apparatus used in the present invention. Processing depth and laser energy dependence characteristics diagram. The absorption spectrum figure with respect to the laser beam of edible yellow No. 5 pigment | dye, paratoluenesulfonic acid sodium salt, and benzoic acid sodium salt. The conceptual diagram of laser induced back surface type transparent substrate fine processing. The figure which shows the processing result which the unprocessed part of the comparative example remained using the saturated solution which does not add the processing promotion substance which melt | dissolved the rhodamine 6G pigment | dye in ethanol as a fluid substance. The figure which shows the processing result of the Example which uses the rhodamine 6G pigment | dye as a laser beam absorption substance which is an Example of this invention as a fluid substance, ethanol as a solvent, and toluene as a process promotion substance. The figure which shows the generation | occurrence | production condition of the crack in case the laser intensity | strength shall be 0.108mJ * pulse- ¹ or more in the Example. The figure which shows the relationship between the laser intensity at the time of using two types of solutions, and a processing state.

  Embodiments of the present invention will be described below with reference to the drawings.

First, an outline of a processing apparatus used in the present invention is shown in FIG.
The laser beam output from the all-solid-state laser oscillator 1 is expanded by a beam expander 2 and then irradiated to a transparent material 6 such as quartz glass through a galvano scanning mirror 3, an F-θ lens 4, and a mirror 5. It concentrates on the back side.
On the other hand, on the back surface of the transparent material 6, the opening surface of the cell 7 containing the fluid substance is pressed, sealed in a liquid-tight manner by a seal ring or the like, and is in direct contact with the fluid substance.

The all-solid-state laser oscillator 1 and the galvano scanning mirror 3 are controlled by the control computer 8 and based on the processing information inputted in advance, the intensity of the laser beam output from the all-solid-state laser oscillator 1 and the irradiation by the galvano scanning mirror 3 The position is controlled.
The laser beam that has passed through the transparent material 6 is condensed on the back surface thereof, and a fluid substance that contacts the back surface of the transparent material 6 absorbs the laser beam at the condensing point, and the laser-induced photothermal reaction causes high temperature and high pressure. A state is created and processed. Therefore, if processing information such as shape and depth is input to the control computer 8 in advance, the intensity of the laser beam and the irradiation position by the galvano scanning mirror 3 are continuously controlled, and processing information is applied to the back surface of the transparent material 6. Can be processed.

Hereinafter, the flowable substance of the present invention will be described along each example.
Example 1
In this example, food yellow No. 5 dye is used as a laser beam absorbing substance, water is used as a solvent for dissolving the same, and paratoluenesulfonic acid sodium salt is used as a processing promoting substance. A solution in which 0.25 g of paratoluenesulfonic acid sodium salt was added per 1 mL of the solution was prepared as a flowable substance, which was accommodated in the cell 7 and processed.

As a comparative example, Nd: as a fluid substance contained in the cell 7 a saturated aqueous solution of only food yellow No. 5 dye as a laser beam absorbing material without adding paratoluenesulfonic acid sodium salt as a processing promoting substance. Laser pulse light of the third harmonic (wavelength 355 nm, pulse width 20 ns) of YVO ₄ laser is emitted under the conditions of a pulse repetition frequency of 10 kHz and a laser intensity of 0.04 mJ · pulse ⁻¹ and condensed through an F-θ lens. The galvano scanning mirror was used to scan at a speed of 60 mm / s.
Irradiation to the interface between the saturated aqueous solution of food yellow No. 5 dye and glass placed on the back side of the soda-lime glass substrate with a thickness of 1.3 mm, and processing is possible even if beam scanning on the same line is repeated twice. Did not happen.
Therefore, when the output of the all-solid-state laser oscillator 1 was increased and the intensity was increased to 0.06 mJ · pulse ⁻¹ , a groove having a width of 11 μm and a depth of 0.8 μm was first obtained by repeating the beam scanning on the same line twice. Formed.

On the other hand, when the fluid substance of the present example was accommodated in the cell 7 and processed, a groove structure was formed by irradiation with a laser intensity of 0.04 mJ · pulse ⁻¹ . The groove structure obtained by repeating the beam scanning on the same line twice showed no damage such as generation of cracks, and had a width of 9 μm and a depth of 0.3 μm.
Further, the groove obtained by increasing the strength to 0.06 mJ · pulse ⁻¹ has a width of 13 μm and a depth of 1.2 μm, and without the addition of paratoluenesulfonate, which is a processing accelerator, under the same conditions. The groove depth is increased by a factor of 1.5 compared to the case where it is created, and the resulting groove structure is damaged such as the occurrence of cracks, or the unprocessed portion where the groove depth does not reach the predetermined value. Did not occur at all.

  In this example, a solution prepared by adding 0.25 g of paratoluenesulfonic acid sodium salt per 1 mL of a solution as a processing accelerator to a saturated aqueous solution of edible yellow No. 5 dye was prepared as a fluid substance. The amount of sodium salt added may be appropriately determined based on the effect of promoting processing, the saturation concentration with respect to water, and the effect on the dissolution concentration of the edible yellow No. 5 pigment. Generally, 0.01 to 1.0 g per 1 mL of the solution is suitable.

(Example 2)
Next, in Example 2, a solution was prepared by adding 0.12 g of sodium benzoate as a processing accelerator to a saturated aqueous solution of edible yellow No. 5 dye, which is the laser beam absorbing material, per 1 mL of the solution.
When processing was performed using this solution, a groove structure was formed even by irradiation with a laser intensity of 0.04 mJ · pulse ⁻¹ . The groove structure obtained by repeating the beam scanning on the same line twice did not show any damage due to the occurrence of cracks, and had a width of 7 μm and a depth of 0.2 μm. The groove obtained by increasing the laser intensity to 0.06 mJ · pulse ⁻¹ has a width of 12 μm and a depth of 1.1 μm. Compared to the case where the saturated aqueous solution of edible yellow No. 5 shown above is used. In addition, the groove depth is increased by a factor of 1.4, and the resulting groove structure does not generate any damage such as cracks or unprocessed portions where the groove depth does not reach the predetermined value. It was.

FIG. 2 shows the processing depth and laser energy dependence characteristics of Examples 1 and 2 and the comparative example.
As can be seen from this figure, in Example 1 using p-toluenesulfonic acid sodium salt as a processing accelerator, and in Example 2 using sodium benzoate, a saturated aqueous solution of edible yellow No. 5 dye without addition of these ( Compared with the comparative example), the laser beam intensity at which machining is started, that is, the machining threshold value is decreased, and the machining depth can be increased with respect to the same laser beam intensity.

  In this example, a solution prepared by adding 0.12 g of sodium benzoate as a processing accelerating substance to a saturated aqueous solution of edible yellow No. 5 dye per mL of the solution was prepared as a fluid substance, but the amount of sodium benzoate added was As described above, it may be determined as appropriate based on the effect of promoting processing, the saturation concentration with respect to water, and the influence on the dissolution concentration of the edible yellow No. 5 pigment. Generally, 0.01 to 1.0 g per 1 mL of the solution is suitable.

  In FIG. 3, the absorption spectrum figure with respect to the laser beam of edible yellow No. 5 pigment | dye, paratoluenesulfonic acid sodium salt, and benzoic acid sodium salt is shown. As can be seen from the figure, paratoluenesulfonic acid sodium salt or benzoic acid sodium salt has an absorption region in a much shorter wavelength range than the wavelength of 355 nm of the irradiated laser beam, and itself has an absorption region of this wavelength. It can be seen that the laser beam is not absorbed at all.

In order to analyze the reason why such para-toluenesulfonic acid sodium salt and benzoic acid sodium salt lower the laser beam intensity processing threshold and increase the processing efficiency and processing accuracy, the concept of laser-induced backside transparent substrate fine processing The figure is shown in FIG.
The incident laser is absorbed by the dye molecules in the solution and converted into heat, and as described above, the temperature rises to 2000 degrees (Non-patent Document 1), and the pressure immediately after the laser beam absorption becomes 10 to 200 MPa. (Non-patent document 2).

Under such high temperature and high pressure, the pigment and solvent molecules existing in this region are partially decomposed, and paratoluenesulfonic acid sodium salt and benzoic acid sodium salt existing in this region are also decomposed by exposure to high temperatures. However, by releasing the binding energy, it functions as a source of additional heat and pressure by releasing heat and pressure or by attaching decomposition products to the glass, which increases the energy density in this region. It is presumed that the etching process is promoted by contributing.
Therefore, despite using an aqueous solution containing water as a solvent as a fluid substance, it is possible to realize processing with high efficiency and accuracy, which is environmentally friendly compared to the case of using an organic solvent, Moreover, since processing in an open space is possible, capital investment can be greatly reduced.

  In Examples 1 and 2, edible yellow No. 5 dye was used as a water-soluble laser beam absorbing substance that uses water as a solvent and exhibits a high absorption rate for a laser beam having a wavelength of 355 nm. Other examples of the laser beam absorbing material include edible yellow No. 4 dye, edible red No. 104 dye, red 213 dye, and green No. 401 dye. May be used. Further, as processing accelerators, so-called water-soluble benzene derivative organic acid salts represented by sodium paratoluenesulfonate and sodium benzoate are effective. Therefore, depending on the material of the transparent material, the required processing accuracy or the wavelength of the irradiated laser beam, the processing threshold of the laser beam intensity is lowered, the processing efficiency is increased for the same laser beam intensity, and the unprocessed part These water-soluble laser beam absorbing materials and processing promoting materials may be combined in various ways so that stable processing with suppressed generation is performed. In any case, it is preferable that the water-soluble laser beam absorbing material has a saturated concentration at which precipitation does not occur in the presence of the selected processing promoting substance.

Example 3
In Example 3, a rhodamine 6G dye as a laser beam absorbing substance, ethanol as a solvent for dissolving the dye, and toluene as a processing accelerator are mixed at a volume ratio of 1: 1 with ethanol to obtain a saturated solution of rhodamine 6G dye. Was prepared as a flowable material. Using the laser pulse light of the second harmonic (wavelength 532 nm, pulse width 35 ns, pulse frequency 5 kHz) of the Nd: YVO ₄ laser used for this kind of processing, it is condensed through an F-θ lens, and galvano A soda-lime glass substrate having a thickness of 1.3 mm was scanned with a scanning mirror at a speed of 60 mm / s. Since ethanol can dissolve rhodamine 6G at a maximum concentration of 0.2 moldm ⁻³ per mL, it has a function as a solvent for dissolving rhodamine 6G at a high concentration. On the other hand, although toluene is also in a liquid state, the soluble rhodamine 6G dye is 1 / 10,000 or less of ethanol, and toluene itself does not have a function of absorbing a laser beam having a wavelength of 532 nm.

As a comparative example, when a rhodamine 6G dye, which is a laser beam absorbing material, is dissolved as a fluid material in ethanol, which is a solvent, and a saturated solution to which no processing accelerator is added is used, the laser intensity is 0.044 mJ · pulse ^−1. The processing was not started by irradiation with, and formation of a groove structure was confirmed for the first time at a laser intensity of 0.067 mJ · pulse ⁻¹ (FIG. 5). However, an unprocessed portion was seen in the processed shape even though the same figure as in FIG. 6 was drawn. Furthermore, when the laser intensity was 0.120 mJ · pulse ⁻¹ or more, generation of cracks was observed.

On the other hand, when the fluid substance of this example is used, a groove structure is formed even by irradiation with an intensity of 0.044 mJ · pulse ⁻¹ , and the groove obtained by repeating the beam scanning on the same line twice. No damage such as cracks was found in the structure, and the width was 21 μm and the depth was 0.7 μm.
Furthermore, the groove obtained by increasing the laser intensity to 0.067 mJ · pulse ⁻¹ has a width of 24 μm and a depth of 1.8 μm. Even in this case, as shown in FIG. Was not seen.
At a laser intensity of 0.086 mJ · pulse ⁻¹ , a groove with a depth of 2.9 μm was obtained, and the groove depth was 2. 2 as compared with a groove formed with a solution of a comparative example not containing toluene under the same conditions. It increased 9 times, and no damage such as generation of cracks was observed in the obtained groove structure. However, when the laser intensity was set to 0.108 mJ · pulse ⁻¹ or more, cracks occurred as shown in FIG.

In FIG. 8, the experimental result about the processing state with respect to the laser intensity at the time of using the fluid substance of a present Example is shown compared with the case of only ethanol.
As can be seen from this figure, in the case of this example, from 0.031 mJ · pulse ⁻¹ , some unprocessed parts exist, but processing is performed, and 0.058 mJ · pulse ⁻¹ to 0.097 mJ · High precision machining can be realized until it reaches pulse- ¹ .
On the other hand, in the case of ethanol alone, processing is started at 0.050 mJ · pulse ⁻¹ , but an unprocessed portion is generated, and cracks are observed from 0.120 mJ · pulse ⁻¹ . High-precision processing was impossible.

  In Example 3, ethanol is used as a solvent having a volume ratio of 0.1 to 3 with respect to ethanol, and rhodamine is used as a laser beam absorbing material exhibiting a high absorption rate for a laser beam having a wavelength of 532 nm. Although 6G dye is used, other examples of the laser beam absorbing material include edible red No. 105 dye and red No. 213 dye. One of these may be used, or these may be mixed as appropriate. . In addition to toluene, aromatic compound derivatives that do not have an absorption region at the wavelength of the laser beam to be irradiated are effective as the processing accelerator. Therefore, depending on the material of the transparent material, the required processing accuracy or the wavelength of the laser beam to be irradiated, the laser energy processing threshold is lowered, the processing efficiency is increased for the same laser energy, and the occurrence of unprocessed parts is suppressed. These laser beam absorbing materials and processing promoting materials may be combined in various ways so that stable processing can be performed. In any case, it is preferable that the organic solvent-soluble laser beam absorbing material has a saturated concentration at which precipitation does not occur in the presence of the selected processing accelerator.

  As described above, according to the present invention, the flowable material used for laser-induced backside transparent substrate microfabrication is decomposed along with the heat generation of the laser beam absorbing material to additionally generate heat and pressure. Since the processing accelerating substance is added, it is possible to reduce the processing threshold value of the required laser beam intensity and to enable processing with a lower intensity laser beam. Furthermore, it is possible to increase the processing efficiency compared to conventional flowable materials and to realize stable processing that suppresses the generation of unprocessed parts, so it is expected to be widely used for fine processing of transparent materials such as glass Is done.

DESCRIPTION OF SYMBOLS 1 All-solid-state laser oscillator 2 Beam expander 3 Galvano scanning mirror 4 F-theta lens 5 Mirror 6 Transparent material 7 Cell 8 Control computer

Claims (6)

The laser beam that has passed through the transparent material is condensed on the back surface thereof, and the fluid substance that contacts the back surface of the transparent material at the condensing point absorbs the laser beam and raises the temperature to near the melting point of the transparent material and is high. A fluid substance used for laser-induced back-type transparent substrate microfabrication that performs etching at the condensing point of the transparent material by generating pressure,
In addition to a laser beam absorbing substance and a solvent that dissolves the substance in a high concentration to make it a fluid substance , it has an absorption region in a short wavelength range with respect to the wavelength of the laser beam, A fluid substance that does not have absorption characteristics, but is added with a processing promoting substance that decomposes with the heat generation of the laser beam absorbing substance and improves processing accuracy and processing speed.   As the laser beam absorbing material, at least one of water-soluble dyes such as food yellow No. 4 dye, food yellow No. 5 dye, food red No. 104 dye, red No. 213 dye, and green No. 401 dye is used as the solvent. The flowable substance according to claim 1, wherein water is used and a benzene derivative organic acid salt such as paratoluenesulfonic acid sodium salt or benzoic acid sodium salt is added as the processing promoting substance.   When edible yellow No. 5 dye was used as the laser absorbing substance, 0.01 to 1.0 g of paratoluenesulfonic acid sodium salt was added as the processing promoting substance per 1 mL of a saturated aqueous solution of the edible yellow No. 5 dye. The fluid material according to claim 2.   When edible yellow No. 5 dye is used as the laser-absorbing substance, 0.01 to 1.0 g of sodium benzoate per 1 mL of a saturated aqueous solution of the edible yellow No. 5 dye is added as the processing accelerator. The flowable substance according to claim 2.   As the laser absorbing material, at least one dye that is soluble in an organic solvent such as edible red No. 105 dye, red No. 213 dye, rhodamine 6G dye is used, ethanol is used as the solvent, and irradiation is performed using toluene, benzene, or the like. The fluid substance according to claim 1, wherein an aromatic compound derivative having no absorption region at the wavelength of the laser beam to be added is added as a processing promoting substance. When rhodamine 6G dye is used as the laser-absorbing substance, toluene is used as the processing promoting substance, toluene is mixed with ethanol at a volume ratio of 0.1 to 3, and the rhodamine 6G dye is mixed. The flowable substance according to claim 5, which is a saturated solution of liquid.