JP2022137321A - Method of manufacturing glass article - Google Patents

Abstract

To provide a method of manufacturing a glass article, the method shortening an etching time period and the glass article including a hole having high perpendicularity and a cutting face.SOLUTION: A method of manufacturing a glass article includes the steps of: preparing a glass substrate having a first surface and a second surface facing each other; forming an initial hole or a modified part in the glass substrate using a laser beam; and immersing the glass substrate in an etching solution having dissolved atmosphere concentration of 8.0 ppm in weight or less based on dissolved oxygen concentration DO and etching the glass substrate by applying an ultrasonic wave to the glass substrate for at least a part of the etching period.SELECTED DRAWING: Figure 2

Description

The present invention relates to a method for manufacturing glass articles.

Conventionally, a desired shape can be separated from a glass substrate by irradiating a glass substrate with a laser, forming a plurality of defect lines so as to draw an outline of a desired shape on the surface, and etching the glass substrate. is known (Patent Document 1). In addition, there is known a technique of irradiating a glass substrate with a laser to form an initial hole and then applying ultrasonic waves when etching the glass substrate to promote penetration and expansion of the initial hole (Patent Reference 2).

U.S. Patent Application Publication No. 2019/0119150 Japanese Patent Publication No. 2016-534017

However, when ultrasonic waves are applied during etching of the glass substrate, the surface properties of the glass substrate may deteriorate.

Accordingly, an object of the present disclosure is to provide a method of manufacturing a high-quality glass article by suppressing deterioration of the surface properties of a glass substrate that occurs during ultrasonic etching.

The present disclosure includes steps of preparing a glass substrate having a first surface and a second surface facing each other; forming an initial hole or a modified portion in the glass substrate using a laser; is immersed in an etching solution having a dissolved atmospheric concentration of 8.0 wtppm or less in terms of dissolved _oxygen concentration DO, and applying ultrasonic waves to the glass substrate for at least a part of the period to etch the glass substrate. A method for manufacturing a glass article is provided.

According to the manufacturing method of the present disclosure, a glass article is manufactured by separating a desired shape from a glass substrate or forming a hole having a desired diameter in the glass substrate while maintaining good surface properties of the glass substrate. can.

It is the figure which showed the manufacturing flow in one manufacturing method of this invention. In one manufacturing method of the present invention, (a) a schematic diagram of the step of preparing a glass substrate in the AA' cross section of FIG. 3, (b) a schematic diagram of the step of forming a modified portion on the glass substrate in the laser irradiation step, and (c) a schematic diagram showing a state in which a desired shape is hollowed out from a glass substrate in an etching process. FIG. 2B is a schematic top view showing how a modified portion is formed along a contour line of a desired shape on the surface of a glass substrate in one manufacturing method of the present invention, and is a top view of FIG. It is a schematic diagram of the laser irradiation apparatus in one manufacturing method of this invention. FIG. 4 is a schematic diagram showing a pulse shape of an oscillation laser in one manufacturing method of the present invention; FIG. 4 is a schematic diagram showing a pulse shape of a burst pulse of an oscillation laser in one manufacturing method of the present invention; It is a schematic diagram of an etching apparatus in one manufacturing method of the present invention. It is the figure which showed the manufacturing flow in one manufacturing method of this invention. In one manufacturing method of the present invention, (a) a schematic diagram of a step of preparing a glass substrate, (b) a schematic diagram of a step of forming an initial hole in a glass substrate in a laser irradiation step, and (c) a glass substrate in an etching step. FIG. 3 is a schematic diagram showing how a through hole is formed in the . It is a schematic diagram showing a cut surface of a glass substrate in one manufacturing method of the present invention.

A method for manufacturing a glass article according to an embodiment of the present invention will be described. Hereinafter, in the first embodiment, a modified portion is formed on a glass substrate by a laser irradiation process so as to draw an outline of a desired shape, the modified portion is removed by etching, and the desired shape is separated. A method for manufacturing a glass article is described in the second embodiment, and a method for manufacturing a glass article by forming an initial hole in a glass substrate by a laser irradiation step, expanding the initial hole by etching to form a hole, and manufacturing a glass article. explain. The embodiment of the present invention is not limited to this, and for example, holes may be formed from the modified portion, or the glass substrate may be separated using the initial holes.

(First embodiment)
First, a method for manufacturing a glass article according to a first embodiment of the present invention will be described with reference to FIGS. 1 to 7. FIG.

FIG. 1 shows the flow of the method for manufacturing a glass article according to the first embodiment of the present invention.

As shown in FIG. 1, in the method for manufacturing a glass article in the first embodiment of the present invention,
(Step S110) a step of preparing a glass substrate having a first surface and a second surface facing each other (glass substrate preparation step);
(Step S120) A step of forming a modified portion on the glass substrate using a laser (laser irradiation step);
(Step S130) The glass substrate is immersed in an etching solution having a dissolved atmospheric concentration of 8.0 wtppm or less in terms of dissolved _oxygen concentration DO, and ultrasonic waves are applied to the glass substrate for at least a part of the period. and etching the glass substrate (etching step).

Details of each step will be described below with reference to FIGS. FIG. 2 schematically shows how the cutout portion 23 is formed in the glass substrate in steps S120 to S130 using cross-sectional views.

(Step S110)
First, a glass substrate 20 to be processed as shown in FIG. 2(a) is prepared. The glass substrate has a first surface 20b and a second surface 20c facing each other.

The material of the glass substrate 20 is not particularly limited. For example, the glass substrate 20 may be made of soda lime glass, aluminosilicate glass, alkali-free glass, quartz, sapphire glass, crystallized glass, or the like.

The thickness of the glass substrate 20 is not particularly limited, but is in the range of 0.05 mm to 3 mm, for example. The thickness of the glass substrate 20 is preferably 1 mm or less from the viewpoint of facilitating the formation of uniform modified portions by laser. In addition, the thickness is preferably 0.7 mm or less, more preferably 0.5 mm or less, from the viewpoint of easily suppressing narrowing of the hole or hollow portion in the etching step. On the other hand, the thickness of the glass substrate 20 is preferably 0.1 mm, more preferably 0.2 mm or more, from the viewpoint of easily suppressing breakage of the glass substrate due to handling during manufacturing.

(Step S120)
Next, the first surface 20b of the glass substrate 20 is irradiated with a laser. In the first embodiment, as shown in the top view of FIG. 3, the reformed portion 21 is formed along the outline 30 of the portion to be separated 22 in order to separate the portion to be separated 22 having a desired shape from the glass substrate. Multiple are formed. FIG. 3 is a top view of FIG. 2(b). Moreover, at this time, as shown in the cross-sectional view of FIG. FIG. 2 corresponds to the AA' section of FIG.

Here, the modified portion 21 refers to a region formed inside the glass substrate 20 where the glass structure is modified. The modified portion 21 is removed faster than the surrounding glass portion in the subsequent etching process. Accordingly, by etching the glass substrate 20 having the modified portion 21, the modified portion 21 is removed relatively faster than the non-modified portion, so that the portion to be separated 22 is separated, resulting in FIG. ), a hollow portion 23 is formed. It should be noted that minute holes or cracks may exist in the reformed portion 21 . If there are fine holes or cracks, the etchant will easily permeate the modified portion, and the etching rate of the modified portion will be further increased.

FIG. 4 schematically shows the configuration of an apparatus that can be used in step S120. As shown in FIG. 4, the laser irradiation device 400 has a stage 450, a laser oscillator 460, a beam adjustment optical system 470, a condenser lens 480, and the like.

First, the glass substrate 20 is placed on the stage 450 so that the second surface 20c faces the stage. The glass substrate may be fixed to the stage. The fixing method is not particularly limited, but it may be held down with a jig or the like, or may be fixed by suction or adhesive. The adsorption is, for example, vacuum adsorption, electrostatic adsorption, or the like.

Next, a laser beam 465 is oscillated from the laser oscillator 460 . The laser beam 465 enters the beam adjusting optical system 470 , and the beam diameter and beam shape are adjusted by the beam adjusting optical system to become the laser beam 475 . The beam adjusting optical system 470 is formed by, for example, a combination of concave lenses and convex lenses. Beam conditioning optics 470 may have an aperture.

The laser beam 475 enters a condenser lens 480 and is condensed into a laser beam 485 . The laser beam 485 is incident on the first surface 20 b of the glass substrate 20 to form the modified portion 21 inside the glass substrate 20 .

Although the wavelength of the laser beam 485 in the first embodiment is not particularly limited, if it is, for example, 3000 nm or less, the modified portion can be easily formed and the thermal effect on the glass substrate can be suppressed. The wavelength of the laser beam 485 is preferably 2050 nm or less, more preferably 1090 nm or less, from the viewpoint that the energy of the laser becomes sufficiently large and the modified portion is easily formed. On the other hand, the wavelength is preferably 350 nm or longer, more preferably 500 nm or longer.

The laser oscillator 460 in the first embodiment is not particularly limited, but may be, for example, a He—Ne laser, an Ar ion laser, an excimer XeF laser, an Er:YAG laser, an Nd:YAG laser, or a Nd:YAG second harmonic laser. and third harmonic lasers, ruby lasers, fiber lasers, and the like.

The average output of the laser beam 485 is preferably 18 W or more, more preferably 35 W or more, from the viewpoint of obtaining sufficient energy to form the modified portion. On the other hand, the average output is preferably 200 W or less from the viewpoint of easily suppressing the occurrence of cracks around the reformed portion 21 when forming the reformed portion 21 .

The laser beam 465 may be continuously oscillated or pulsed. Pulse oscillation is preferable because the peak output increases and sufficient energy can be obtained, so that the reformed portion can be easily formed. The pulse oscillation may be in a normal pulse mode, or may be oscillated as a burst pulse.

FIG. 5 schematically shows an example 500 of the waveform of the laser beam 485 when oscillated in a normal pulse mode. The pulse width 501 is preferably 1 nsec or less from the viewpoint that the thermal effect is small and the occurrence of cracks around the modified portion can be suppressed. On the other hand, the pulse width 501 is preferably 100 fsec or more.

FIG. 6 schematically shows an example 600 of a burst pulse waveform. As shown in FIG. 6, a burst pulse is a pulse consisting of bursts 610 produced by dividing a single pulse. An interval 611 between bursts 610 (hereinafter referred to as burst interval 611) is on the order of picoseconds, for example, and an interval 621 between pulses 620 (hereinafter referred to as pulse interval 621) is on the order of nanoseconds, for example. Burst interval 611 is preferably 10 psec or more. The pulse interval 621 is preferably 1 nsec or less. Each pulse 620 includes, for example, two or more bursts 610 and preferably four or more bursts 610 . On the other hand, each pulse 620 includes, for example, 20 or fewer bursts 610 and preferably 10 or fewer bursts 610 . Under the above conditions, it is easy to form the modified portion, and it is easy to suppress thermal melting and crack generation around the hole.

The modified portion 21 is formed inside the glass substrate 20 by the laser irradiation process as described above. Further, by scanning and irradiating the laser 485 so as to draw a contour line of a desired shape, a plurality of modified portions 21 are formed along the contour line 30 of the portion to be separated 22 as shown in FIG. be. The interval between the modified portions 21 is preferably 10 μm or less, more preferably 7 μm or less, from the viewpoint of shortening the time required for hollowing out in the etching process. On the other hand, the interval between the modified portions 21 is preferably 2 μm or more.

(Step S130)
Next, the glass substrate 20 on which the modified portion 21 is formed is etched. FIG. 7 schematically shows an example of an etching apparatus 700 used in the etching process. As shown in FIG. 7, the etching apparatus 700 has an external bath 710 , an etching bath 720 and an ultrasonic generator 730 . The etching tank 720 is installed inside the external tank 710 , the external tank 710 contains a propagating liquid 715 , and the etching tank 720 contains an etching liquid 725 .

The propagation liquid 715 is not particularly limited, but is, for example, water, and has the role of propagating the ultrasonic waves 735 generated from the ultrasonic generator 730 to the etching tank 720 .

The etchant is not particularly limited, but for example, a solution containing hydrofluoric acid (aqueous solution of hydrogen fluoride) is selected. The etching solution may be hydrofluoric acid alone, or may contain a mixed acid such as hydrochloric acid (an aqueous solution of hydrogen chloride) or an aqueous nitric acid solution. The etchant preferably contains a mixed acid containing either hydrochloric acid or an aqueous nitric acid solution, or both, from the viewpoint of dissolving the salt generated during etching and suppressing the phenomenon that the salt blocks the modified portion. can be The etchant is more preferably an aqueous nitric acid solution. A high effect can be expected when the etchant is a nitric acid aqueous solution.

The concentration of hydrogen fluoride in the etchant is preferably 0.5 wt % or more, more preferably 1.0 wt % or more, relative to the entire etchant from the viewpoint of sufficient etching. On the other hand, the concentration of hydrogen fluoride is preferably 5.0 wt % or less, more preferably 3.5 wt % or less, relative to the entire etching solution, from the viewpoint of increasing the selectivity and facilitating the formation of highly vertical holes. is.

When the etching solution contains hydrochloric acid, the concentration of hydrogen chloride is preferably 1 wt % or more, more preferably 5 wt % or more, and further preferably 5 wt % or more, relative to the entire etching solution, from the viewpoint that the effect of dissolving the salt is significantly exhibited. Preferably, it is 8 wt % or more. On the other hand, it is preferably 20 wt % or less, more preferably 15 wt % or less, and even more preferably 12 wt % or less with respect to the entire etching liquid, from the viewpoint that the removal speed of the modified portion by hydrofluoric acid can be easily maintained.

When the etching solution contains nitric acid, the concentration of nitric acid is preferably 1 wt % or more, more preferably 5 wt % or more, and still more preferably 5 wt % or more, relative to the entire etching solution, from the viewpoint that the effect of dissolving salts is significantly exhibited. is 8 wt % or more. On the other hand, the concentration of nitric acid is preferably 20 wt % or less, more preferably 15 wt % or less, and even more preferably 12 wt % or less with respect to the entire etching solution, from the viewpoint that the removal speed of the modified portion by hydrofluoric acid can be easily maintained. be.

Using such an etching apparatus 700, the glass substrate 20 is etched. The glass substrate 20 is placed in an etching bath 720 and immersed in an etchant 725 . In FIG. 7, a support for the glass substrate 20 is omitted, and the method for supporting the glass substrate 20 is not particularly limited as long as the surface is not damaged, and a known method can be applied.

Next, an ultrasonic wave 735 is generated from the ultrasonic generator 730 , propagates through the propagation liquid 715 , and vibrates the etching bath 720 . The vibration of the etching bath 720 propagates through the etchant 725 , and as a result, ultrasonic waves are also propagated to the glass substrate 20 . Thereby, the glass substrate 20 vibrates. The mechanism of forming hollowed portions in a glass substrate by applying ultrasonic waves will be described below with reference to FIGS. 2(b) and 2(c).

2(b) and 2(c) show how the glass substrate 20 is etched by the above-described method and the modified portion 21 is removed, thereby separating the portion to be separated 22 and forming the cutout portion 23. Schematically shows a cross-sectional view of. A dashed line 24 in FIG. 2(c) represents a boundary line between the non-modified portion of the glass substrate (a portion of the glass substrate other than the modified portion) and the modified portion in FIG. The surface of the glass substrate in (b) is represented.

As shown in FIG. 7, by being immersed in the etchant 725, the modified portion 21 of the glass substrate 20 is removed as shown in FIG. Other glass portions, ie, non-modified portions, are also removed. However, as described above, the speed at which the modified portion 21 is removed is faster than that of the surrounding glass. A cut-out portion 23 including a modified portion can be formed. Then, by bringing the adjacent cut-out portions 23 close to each other or joining them together, the portion to be separated 22 can be separated from the glass substrate.

Furthermore, it is considered that the following phenomenon progresses by applying ultrasonic waves, and the separation of the part to be separated 22 becomes possible in a short time. (i) The outermost surface of the modified portion 21 is removed by reacting with the etchant 725 to form a concave portion on the surface of the glass substrate 20 . (ii) The etchant 725 is vibrated by ultrasonic waves to reduce the surface tension and improve the penetration of the etchant into the recesses. Furthermore, by vibrating the glass substrate 20 with the ultrasonic waves, the removed modified portion quickly separates from the non-modified portion and quickly diffuses throughout the etchant. (iii) Thereby, an unreacted etchant is supplied to the new surface of the modified portion exposed at the bottom of the recess. By repeating the above phenomena (i) to (iii), the reformed portion is selectively removed, and the separation of the portion to be separated 22 can be separated in a short time.

On the other hand, the application of ultrasonic waves may damage the surface of the glass substrate. Therefore, in one embodiment of the present invention, the dissolved atmospheric concentration in the etchant 725 is set to 8.0 wtppm or less in terms of dissolved _oxygen concentration conversion DO, for example, in terms of alternative dissolved oxygen concentration in pure water (described later). As a result, it was found that damage to the surface of the glass substrate can be significantly suppressed without adversely affecting the removal of the modified portion by etching. The principle will be described below, but the principle that produces the above effect is not limited to this.

By applying ultrasonic waves, cavitation (cavities) is generated in the etchant, and a phenomenon occurs in which the glass substrate surface is impacted when the cavitation collapses. Due to the impact force caused by cavitation, minute fracture areas can be generated on the surface of the glass substrate. As the etching is continued, the micro-destroyed regions may expand and connect to become apparent as surface roughness. In the present application, these minute fracture areas and surface roughness are referred to as damage.

The amount of cavitation generated increases as the gas concentration dissolved in the etchant 725 increases. Therefore, it is effective to reduce the concentration of the dissolved gas in order to prevent damage to the surface of the glass substrate due to cavitation.

Here, the etching apparatus 700 is installed in the atmosphere, and the gas dissolved in the etching solution 725 is the atmosphere unless the gas is artificially dissolved in the etching solution 725 . Therefore, it is possible to suppress damage to the surface of the glass substrate due to cavitation by controlling the concentration in the atmosphere dissolved in the etchant.

The method for adjusting the dissolved atmospheric concentration in the etching solution is not particularly limited, but it can be adjusted, for example, by degassing using a hollow fiber filter and a vacuum pump.

Gases dissolved in the etchant consist of atmospheric components, that is, oxygen, carbon dioxide, nitrogen, and other gases, unless otherwise devised. For example, the dissolved _oxygen concentration DO can be used as an index value reflecting the amount of dissolved air. The dissolved oxygen concentration D 2 _O is advantageous in that it can generally be easily measured. However, since it may be technically difficult to measure the dissolved oxygen concentration in a hydrofluoric acid solution more precisely, the dissolved oxygen concentration in one embodiment of the present invention is, for example, can be substituted by the measured value of
(Procedure 1) The dissolved atmospheric concentration of the etchant is adjusted under certain conditions.
(Procedure 2) Adjust the dissolved air concentration of pure water under the same conditions as in Procedure 1.
(Procedure 3) The dissolved oxygen concentration of pure water is measured using a portable fluorescent dissolved oxygen meter. As a portable fluorescent dissolved oxygen meter, for example, HQ30d manufactured by HACH is used. The measured value at this time is the “alternative dissolved oxygen concentration in pure water”, and the measured value can be used as the “dissolved oxygen concentration D _O ” of the etching solution.

For procedure 2, if the method of adjusting the dissolved air is, for example, degassing using a hollow fiber filter and a vacuum pump, the conditions can be matched by setting the pressure reduction value to be equal to the pressure reduction value in procedure 1.

In one embodiment of the present invention, preferably, the dissolved atmospheric concentration in the etching solution can be reduced to 8.0 wtppm or less in terms of dissolved oxygen concentration D 2 _O , thereby suppressing the occurrence of cavitation and improving the glass substrate surface. It was found that the damage of The dissolved atmospheric concentration is preferably 7.5 wtppm or less, more preferably 7.0 wtppm or less, and even more preferably 6.5 wtppm or less in terms of dissolved _oxygen concentration DO.

Here, when the dissolved air concentration is reduced from 8.0 wtppm in terms of dissolved _oxygen concentration DO, the occurrence of cavitation decreases, but when the dissolved air concentration is around 4.0 wtppm in terms of dissolved _oxygen DO , the amount of cavitation increases again, and a phenomenon that takes a maximum value may occur. When the dissolved atmospheric concentration is further reduced, the amount of cavitation generated begins to decrease again. This is because when the amount of dissolved air is large, excess air that does not contribute to cavitation consumes energy. It is thought that this is because there is no surplus atmosphere and energy loss is reduced.

Therefore, the dissolved atmospheric concentration is preferably |D _O −4.0|>0 wtppm, more preferably |D _O −4.0|≧0.1 wtppm, still more preferably |D _O in terms of dissolved oxygen concentration D _O −4.0|≧0.2 wtppm, more preferably |D _O −4.0|≧0.3 wtppm, more preferably |D _O −4.0|≧0.4 wtppm, still more preferably |D _O −4 .0|≧0.5 wtppm, more preferably |D _O −4.0|≧0.6 wtppm, still more preferably |D _O −4.0|≧0.7 wtppm, still more preferably |D _O −4.0 |≧0.8 wtppm, more preferably |D _O −4.0|≧0.9 wtppm.

Further, the dissolved atmospheric concentration is generally 0.05 wtppm or more, preferably 0.1 wtppm or more in view of the control cost, in terms of the dissolved _oxygen concentration DO.

Next, the frequency range of ultrasonic waves 735 will be described. Although the frequency of the ultrasonic wave 735 is not particularly limited, it is preferably 200 kHz or less, more preferably 100 kHz or less, from the viewpoint that the ultrasonic wave is likely to promote the removal of the modified portion. Also, from the viewpoint of suppressing the degree of constriction described below and significantly improving the selectivity, the frequency is preferably 40 kHz or less, more preferably less than 40 kHz. Ultrasonic waves of 20 kHz or higher are generally used.

After separating the part to be separated 22, the cutout part 23 formed by removing the reformed part 21 and the part including the non-reformed part around the reformed part 21 is as shown in FIG. 2(c). May have strictures. The narrowed portion refers to a portion in which the width inside the cutout portion 23 is smaller than the width of the cutout portion on the surface of the glass substrate. Such a narrowed portion is formed by removing the surrounding glass portion while the modified portion 21 is being removed. By reducing the degree of constriction, the shape of the inner wall of the cutout portion 23 can be made nearly vertical, and the time required for the cutout can be shortened.

Here, the degree of stenosis is expressed using the degree of stenosis C ₁ (τ). The constriction degree C ₁ (τ) is represented by the following formula (2).
C ₁ (τ)=(D ₁ −D ₂ )/t ₁ (2)
Here, τ represents the etching time of the glass substrate 20 for the separation of the part to be separated 22 ( _FIG . 3), D1 is the width of the cutout 23 on the _first surface 20b, and D2 is the cutout. t1 represents the minimum width of the interior of the portion 23, and t1 represents the thickness of the glass substrate ₂₀ after etching for the time τ.

Moreover, in order to perform etching efficiently in a short time and form holes with a low degree of constriction, it is necessary to selectively remove the modified portion 21 from the surrounding glass. Here, as an index representing the selectivity of the reforming section 21 to glass, a selection ratio S(τ) represented by the following formula (3) is defined.
S(τ)=t ₁ /t ₀ (3)
Here, τ represents the etching time of the glass substrate 20 for separating the part to be separated 22, _t0 is the thickness of the glass substrate ₂₀ before etching, and t1 is the glass substrate after etching for the time τ. 20 thickness.

The closer the constriction degree C1 is to ₀ , the more the inner wall of the hollowed-out portion 23 has a nearly vertical shape, which is preferable. Moreover, it is possible to shorten the time required for separation of the part to be separated 22, which is also preferable from the viewpoint of production efficiency.

The selection ratio S takes a value in the range of 0 to 1, and the closer S is to 1, the more preferable the modified portion is removed. Furthermore, by increasing the selectivity S, it is possible to reduce the amount of removal of the first surface 20b and the second surface 20c until the hollowed out portion is formed. It is possible to suppress the phenomenon that latent scratches are enlarged and deepened and become apparent, and it is easy to manufacture a glass article with less surface damage.

The degree of constriction C1 can be brought close to ₀ , and the selection ratio S can be brought close to 1. From the viewpoint that the above-described phenomenon in which latent flaws are enlarged and deepened to become apparent can be suppressed, the frequency of ultrasonic waves 735 is is preferably 200 kHz or less, more preferably 100 kHz or less, and even more preferably 40 kHz or less.

On the other hand, the lower the frequency of the ultrasonic waves, the larger the size of the generated cavitation, and the larger the shock wave generated when the cavitation collapses. Therefore, when using lower frequency ultrasonic waves, the effect of suppressing cavitation damage by controlling the air dissolved in the etchant is remarkably exhibited.

Furthermore, the frequency of the ultrasonic waves is preferably modulated. The method of modulation is not particularly limited, but examples include stepwise switching of frequencies, sweeping, and the like. By modulating the frequency, the position of the standing wave changes in the tank, so uneven etching can be suppressed, and furthermore, since the position where cavitation occurs changes, damage is concentrated on a specific position on the surface of the glass substrate 20. It is preferable because it prevents Although the method of modulating the frequency is not particularly limited, the effect described above can be easily obtained by, for example, periodically changing the frequency. On the other hand, an ultrasonic wave may be applied at a medium frequency of 40 kHz to 200 kHz in the initial stage of etching, and then switched to a low frequency of 40 kHz or less. By doing so, cracks generated around the modified portion due to laser irradiation are suppressed from propagating due to the application of low-frequency ultrasonic waves. By switching to , the constriction can be suppressed and the selectivity can be improved, which is preferable.

Ultrasonic waves are applied during at least part of the period during which the glass substrate is immersed in the etchant. For example, the voltage may be applied for the entire period, or intermittent operation may be performed in which the voltage is applied and the voltage is not applied. Preferably, by intermittent operation, large bubbles remaining in the liquid that inhibit the propagation of ultrasonic waves rise during the period in which ultrasonic waves are not applied, and collapse at the liquid surface, thereby increasing the efficiency of ultrasonic waves. propagation can be maintained.

The output of ultrasonic waves is preferably set to 0.5 W/cm ² or more, more preferably 0.7 W or more. On the other hand, the output of ultrasonic waves is 2 W/cm ² or less. The ultrasonic power may be varied during etching. Preferably, at the beginning of the etching period, the power is set to low and then changed to high. By setting in this way, it is possible to suppress the cracks generated around the modified portion by laser irradiation from propagating in the early stage of etching. By changing, the removal time of the reformed portion can be shortened.

(Second embodiment)
Next, a second embodiment will be described with reference to FIGS. 8 and 9. FIG. In the second embodiment, after an initial hole is formed in the glass substrate in the laser irradiation step, the initial hole is expanded by etching to form a hole having a desired opening diameter. FIG. 8 shows the flow of the method for manufacturing a glass article according to the second embodiment of the present invention.

As shown in FIG. 8, in the method for manufacturing a glass article in the first embodiment of the present invention,
(Step S810) a step of preparing a glass substrate having a first surface and a second surface facing each other (glass substrate preparation step);
(Step S820) forming an initial hole in the glass substrate using a laser (laser irradiation step);
(Step S830) The glass substrate is immersed in an etching solution having a dissolved oxygen concentration of 8.0 wtppm or less in terms of dissolved oxygen concentration D 2 _O , and ultrasonic waves are applied to the glass substrate for at least a part of the period. It is characterized by etching a glass substrate.

Differences from the first embodiment will be described below. (Step S810) is the same as (Step S110).

(Step S820)
As shown in FIG. 9, in the laser irradiation step in the second embodiment, an initial hole 91 is formed instead of the modified portion. Here, the initial hole means a fine hole that has an opening on at least one surface and extends inside the glass substrate 20 . The initial hole 91 may be penetrated, or may have a closed portion in the middle. Once the initial hole has been etched, a hole 93 can be formed by removing the blockage and widening the initial hole. The hole may be a through hole or a stop hole with one side blocked (blind hole). When it is desired to finally form a through hole, the initial hole may be formed so as to communicate from the first surface 20b to the second surface 20c. An initial hole having The laser optical system and irradiation conditions are designed according to known techniques.

A plurality of initial holes 91 may be formed. It is preferable to form the initial holes with an interval of 10 μm or more, because it is possible to suppress the joining of the holes after etching and the propagation of cracks to adjacent holes.

(Step S830)
Next, the glass substrate 20 in which the initial holes 91 are formed is etched. The configuration and preferred aspects of the etching process conform to the process S130 of the first embodiment.

The application of ultrasonic waves is also effective in expanding the initial hole 91 . When the glass substrate 20 vibrates due to the application of ultrasonic waves, the exchange between the reacted etchant inside the initial hole 91 and the external etchant is promoted, and the unreacted etchant is constantly supplied to the inside of the initial hole 91 . Therefore, expansion of the initial hole 91 is promoted.

The etching process is performed until the hole 93 has a desired opening diameter. The hole 93 thus formed may also have a constriction, similar to the cutout 23 described in the first embodiment. The degree of constriction C ₂ (τ) is defined by Equation (4) below.
C ₂ (τ)=(d ₁ −d ₂ )/t ₁ (4)
Here, τ represents the time taken to etch the glass substrate ₂₀ to form the holes 93, d1 is the opening diameter of the holes 93 on the _first surface 20b, and d2 is the minimum diameter inside the holes 93. and t1 represents the thickness of the glass substrate ₂₀ after etching for time τ.

At this time, the selection ratio S(τ) is defined by the following equation (5). In this case, the selectivity ratio is a measure of how fast the initial pore expansion progressed relative to the removal of the glass substrate surface.
S(τ)=t ₁ /t ₀ (5)
Here, τ represents the time for etching the glass substrate 20 to form the hole 93, _t0 is the thickness of the glass substrate 20 before etching, and t1 is the thickness of the glass substrate ₂₀ after etching for the time τ. represents

The closer the constriction degree _C2 is to 0, the more the inner wall of the hole 93 becomes nearly vertical, which is preferable.

The selection ratio S takes a value in the range of 0 to 1. The closer the S is to 1, the faster the expansion of the initial hole progresses, so the time required to form the hole 93 can be shortened, which is preferable. Furthermore, by increasing the selectivity S, the amount of removal of the first surface 20b and the second surface 20c until the holes 93 are formed can be reduced. It is possible to suppress the phenomenon in which latent scratches are enlarged, deepened, and actualized, and a glass article with less surface damage can be produced.

Also, one manufacturing method of the present invention can be applied to cutting of a glass substrate. As shown in FIG. 10, when one manufacturing method of the present invention is used for cutting a glass substrate, the constriction degree C3 is obtained by using the protrusion amount d3 of the cut surface 101 instead of the expressions ( ₂ ) and ( ₄ ). can be used for evaluation according to the following formula (6).
C ₃ =d ₃ ×2/t ₁ (6)

20 Glass substrate 20b First surface of glass substrate 20c Second surface of glass substrate 21 Modified portion 22 Pre-separation portion 23 Hollow portion 24 Modified portion before etching or boundary between initial hole and glass portion 25 Before etching Glass substrate surface 30 Contour line 91 Initial hole 93 Hole 101 Cut surface d ₁ Opening diameter of first surface of hole of glass substrate d ₂ Minimum diameter inside hole of glass substrate d ₃ Protrusion amount of cut surface of glass substrate D ₁ Width of the _first surface in the hollowed portion D2 Minimum width of the inside of the hollowed portion _t0 Thickness of the glass substrate before the etching process t1 Thickness of the glass substrate after the etching process 400 Laser irradiation device 450 _Stage 460 Laser oscillator 465 Laser beam 470 Beam adjusting optical system 475 Laser beam 480 Condensing optical system 485 Laser beam 500 Laser pulse 501 Pulse width 600 Laser burst pulse 610 1 burst 611 Burst width 620 1 pulse 621 Pulse width 700 Etching device 710 External tank 715 Propagating liquid 720 Etching tank 725 Etching liquid 730 Ultrasonic generator 735 Ultrasonic

Claims (4)

providing a glass substrate having first and second surfaces facing each other;
forming an initial hole or a modified portion in the glass substrate using a laser;
The glass substrate is immersed in an etching solution having a dissolved atmospheric concentration of 8.0 wtppm or less in terms of dissolved oxygen concentration D 2 _O , and ultrasonic waves are applied to the glass substrate for at least a part of the period, thereby removing the glass substrate. provided with an etching process,
A method for manufacturing a glass article. The method for producing a glass article according to claim 1, wherein the dissolved _oxygen concentration DO satisfies formula (1).
|D _O -4.0|>0wtppm (1) 3. The method for manufacturing a glass article according to claim 1, wherein the ultrasonic wave has a frequency of 200 kHz or less. The method for producing a glass article according to any one of claims 1 to 3, wherein the ultrasonic frequency is less than 40 kHz.

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