WO2021033610A1

WO2021033610A1 - Method for producing glass article

Info

Publication number: WO2021033610A1
Application number: PCT/JP2020/030698
Authority: WO
Inventors: 貴之河原; 康章渡邉; 浩平堀内
Original assignee: Ａｇｃ株式会社
Priority date: 2019-08-19
Filing date: 2020-08-12
Publication date: 2021-02-25
Also published as: TW202108537A; JP2022137321A

Abstract

This method for manufacturing a glass article comprises: a step for preparing a glass substrate having a first surface and a second surface facing each other; a step for forming an initial hole or a modified portion on the glass substrate using a laser; and a step for etching the glass substrate by immersing the glass substrate in an etching solution having a dissolved atmospheric concentration of at most 8.0 wtppm in terms of a dissolved oxygen concentration D_O and applying ultrasonic waves to the glass substrate for at least a part of the etching duration.

Description

Manufacturing method of glass goods

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

Conventionally, a desired shape can be separated from a glass substrate by irradiating the glass substrate with a laser, forming a plurality of defect lines so as to draw a contour line of a desired shape on the surface, and etching the glass substrate. Is known (Patent Document 1). Further, a technique is known that promotes penetration and expansion of initial holes by irradiating a glass substrate with a laser to form initial holes and then applying ultrasonic waves when etching the glass substrate (patented). Document 2).

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

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

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

In the present disclosure, a step of preparing a glass substrate having a first surface and a second surface facing each other, a step of forming an initial hole or a modified portion in the glass substrate by using a laser, and the glass. the substrate, the dissolved air concentration is immersed in the etching solution is 8.0wtppm or less dissolved oxygen concentration D _O conversion, by applying at least a portion of the period, the ultrasound on the glass substrate, etching the glass substrate Provided is a method for manufacturing a glass article, which comprises a process.

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

It is a 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 in the AA'cross section of FIG. 3, and (b) a schematic diagram of a step of forming a modified portion on the glass substrate in the laser irradiation step. And (c) is a schematic view showing how a desired shape is hollowed out from a glass substrate in the etching step. FIG. 2B is a schematic view showing from the upper surface how a modified portion is formed on the surface of a glass substrate along a contour line having a desired shape in one manufacturing method of the present invention, and is a top view of FIG. 2B. It is a schematic diagram of the laser irradiation apparatus in one manufacturing method of this invention. It is a schematic diagram which shows the pulse shape of the oscillation laser in one manufacturing method of this invention. It is a schematic diagram which shows the pulse shape of the burst pulse of the oscillation laser in one manufacturing method of this invention. It is a schematic diagram of the etching apparatus in one manufacturing method of this invention. It is a 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 initial holes in the glass substrate in the laser irradiation step, and (c) a glass substrate in the etching step. It is a schematic diagram which showed the appearance that the through hole is formed in. It is a schematic diagram which showed the cut surface of the glass substrate in one manufacturing method of this invention. It is a graph which shows the relationship between the dissolved atmospheric concentration and the glass substrate surface damage in Example (Example 1-1) of this invention. It is a graph which shows the relationship between the dissolved atmospheric concentration and the glass substrate surface damage in Example (Example 1-3) of this invention. It is a graph which shows the relationship between the ultrasonic frequency, the selection ratio of the hole of a glass substrate, and the degree of stenosis in the Example (Example 2-1 to Example 2-7) of this invention. It is a graph which shows the relationship between the ultrasonic frequency, the selection ratio of a hole of a glass substrate, and the degree of stenosis in an Example (Example 2-8 to Example 2-14) of this invention.

A method for manufacturing a glass article according to an embodiment of the present invention will be described. In the following, in the first embodiment, a modified portion is formed on the glass substrate by a laser irradiation step 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 will be described. Further, in the second embodiment, a method of forming an initial hole in a glass substrate by a laser irradiation step and expanding the initial hole by etching to form a hole to manufacture a glass article will be described. 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 the first embodiment of the present invention will be described with reference to FIGS. 1 to 7.

FIG. 1 shows a flow of a 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 (step S110). (Glass substrate preparation step), (Step S120) a step of forming a modified portion on the glass substrate using a laser (laser irradiation step), and (Step S130) the glass substrate having a dissolved atmospheric concentration and dissolved oxygen. immersed in the etching solution is 8.0wtppm or less at a concentration D _O terms, at least part of the period, by applying ultrasonic waves to the glass substrate, and wherein the etching the glass substrate (etching step) ..

The details of each process will be described below with reference to FIGS. 2 to 7. FIG. 2 schematically shows how the hollow portion 23 is formed on the glass substrate by the steps S120 to S130 by using a cross-sectional view.

(Step S110)
First, a glass substrate 20 for processing as shown in FIG. 2A 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 soda lime glass, aluminosilicate glass, non-alkali glass, quartz, sapphire glass, crystallized glass or the like.

The thickness of the glass substrate 20 is not particularly limited, but is, for example, in the range of 0.05 mm to 3 mm. The thickness of the glass substrate 20 is preferably 1 mm or less from the viewpoint that a homogeneous modified portion can be easily formed by a laser. The thickness is preferably 0.7 mm or less, more preferably 0.5 mm or less, from the viewpoint of easily suppressing the narrowing of the hole or the 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 cracking of the glass substrate due to handling during manufacturing.

(Step S120)
Next, the laser is applied to the first surface 20b of the glass substrate 20. In the first embodiment, as shown in the top view of FIG. 3, in order to separate the planned separation portion 22 having a desired shape from the glass substrate, the reforming portion 21 is formed along the contour line 30 of the planned separation portion 22. Multiple are formed. FIG. 3 is a top view of FIG. 2 (b). At this time, as shown in the cross-sectional view of FIG. 2B, the modified portion 21 is formed inside the glass substrate 20 from the surface 20b to 20c of the glass substrate 20. FIG. 2 corresponds to the AA'cross section of FIG.

Here, the modified portion 21 refers to a region where the glass structure has been altered, which is formed inside the glass substrate 20. The modified portion 21 is removed at a higher speed than the surrounding glass portion in the subsequent etching step. As a result, 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 planned separation portion 22 is separated, and FIG. 2 (c) ), The hollow portion 23 is formed. There may be fine holes or cracks in the modified portion 21. When there are fine holes or cracks, the etching solution easily penetrates into the modified portion, and the etching rate of the modified portion becomes even faster.

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

First, the glass substrate 20 is installed on the stage 450 so that the second surface 20c is on the stage side. The glass substrate may be fixed to the stage. The fixing method is not particularly limited, but it may be suppressed by a jig or the like, and may be suction-fixed or adhesively fixed. The adsorption is, for example, vacuum adsorption, electrostatic adsorption, or the like.

Next, the laser beam 465 is oscillated from the laser oscillator 460. The laser beam 465 is incident on the beam adjusting optical system 470, and the beam diameter and the 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 a concave lens and a convex lens. The beam adjusting optical system 470 may have an aperture.

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

The wavelength of the laser beam 485 in the first embodiment is not particularly limited, but if it is, for example, 3000 nm or less, it is easy to form a modified portion and the heat 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 more, more preferably 500 nm or more.

The laser oscillator 460 in the first embodiment is not particularly limited, and is, for example, a He-Ne laser, an Ar ion laser, an Exima XeF laser, an Er: YAG laser, an Nd: YAG laser, and a second harmonic laser of Nd: YAG. And the third harmonic laser, ruby laser, fiber laser 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 that sufficient energy can be obtained to form the modified portion. On the other hand, the average output is preferably 200 W or less from the viewpoint that it is easy to suppress the generation of cracks around the modified portion 21 when the modified portion 21 is formed.

The laser beam 465 may be continuously oscillated or may be pulse oscillated. When the pulse is oscillated, the peak output becomes large and sufficient energy can be obtained, so that the modified portion is easily formed, which is preferable. The pulse oscillation may be 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 the normal pulse mode. The pulse width 501 is preferably 1 nsec or less from the viewpoint that the thermal influence is small and the generation 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, the burst pulse is a pulse composed of burst 610 generated by dividing a single pulse. The interval 611 of each burst 610 (hereinafter referred to as burst interval 611) is, for example, in the picosecond order, and the interval 621 of each pulse 620 (hereinafter, referred to as pulse interval 621) is, for example, in the nanosecond order. The burst interval 611 is preferably 10 psec or more. The pulse interval 621 is preferably 1 nsec or less. Each pulse 620 comprises, for example, two or more bursts 610, preferably four or more bursts 610. On the other hand, each pulse 620 includes, for example, 20 or less bursts 610, preferably 10 or less bursts 610. Under the above conditions, it is easy to form a modified portion, and it is easy to suppress thermal melting and crack generation around the holes.

By the laser irradiation process as described above, the modified portion 21 is formed inside the glass substrate 20. Further, by scanning the laser beam 485 so as to draw a contour line having a desired shape and irradiating the laser beam 485, a plurality of modified portions 21 are formed along the contour line 30 of the planned separation portion 22 as shown in FIG. Will be done. The distance between the modified portions 21 is preferably 10 μm or less, more preferably 7 μm or less, from the viewpoint that the time required for hollowing out in the etching step can be shortened. On the other hand, the distance between the modified portions 21 is preferable from the viewpoint that the laser is absorbed more by the modified portion 21 formed earlier and the modified portion to be formed next is not formed well. It is 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 the etching apparatus 700 used in the etching process. As shown in FIG. 7, the etching apparatus 700 includes an external tank 710, an etching tank 720, and an ultrasonic wave generator 730. The etching tank 720 is installed inside the outer tank 710, and the outer tank 710 contains the propagation liquid 715, and the etching tank 720 contains the etching liquid 725.

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

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

The concentration of hydrogen fluoride in the etching solution is preferably 0.5 wt% or more, more preferably 1.0 wt% or more, based on the entire etching solution, from the viewpoint that etching proceeds sufficiently. On the other hand, the concentration of hydrogen fluoride is preferably 5.0 wt% or less, more preferably 3.5 wt% or less, based on the entire etching solution, from the viewpoint of increasing the selectivity and easily forming pores with high verticality. 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, with respect to the entire etching solution, from the viewpoint that the effect of dissolving the salt is significantly exhibited. It is preferably 8 wt% or more. On the other hand, from the viewpoint that the removal speed of the modified portion by hydrofluoric acid can be easily maintained, it is preferably 20 wt% or less, more preferably 15 wt% or less, still more preferably 12 wt% or less with respect to the entire etching solution.

When the etching solution contains nitric acid, the concentration of nitric acid is preferably 1 wt% or more, more preferably 5 wt% or more, still more preferably 5 wt% or more, based on the entire etching solution, from the viewpoint that the effect of dissolving the salt 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, still more preferably 12 wt% or less with respect to the entire etching solution from the viewpoint of easily maintaining the removal speed of the modified portion by hydrofluoric acid. is there.

The glass substrate 20 is etched using such an etching apparatus 700. The glass substrate 20 is arranged in the etching tank 720 and immersed in the etching solution 725. In FIG. 7, the support tool for the glass substrate 20 is omitted, and the method of 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, the ultrasonic wave 735 is generated from the ultrasonic wave generator 730, and the ultrasonic wave 735 propagates the propagating liquid 715 to vibrate the etching tank 720. The vibration of the etching tank 720 propagates through the etching solution 725, and as a result, ultrasonic waves are also propagated to the glass substrate 20. As a result, the glass substrate 20 vibrates. Hereinafter, a mechanism in which a hollow portion is formed on the glass substrate by ultrasonic wave application etching will be described with reference to FIGS. 2 (b) and 2 (c).

In FIGS. 2B and 2C, the glass substrate 20 is etched by the above method and the modified portion 21 is removed, so that the planned separation portion 22 is separated and the hollowed portion 23 is formed. The cross-sectional view of is schematically shown. The broken line 24 in FIG. 2C represents the boundary line between the non-modified portion (the portion other than the modified portion of the glass substrate) and the modified portion of the glass substrate in FIG. 2B, and the alternate long and short dash line 25 is FIG. Represents the surface of the glass substrate in (b).

As shown in FIG. 7, by immersing in the etching solution 725, the modified portion 21 of the glass substrate 20 is removed as shown in FIG. 2C, and at the same time, the modified portion 21 of the glass substrate 20 is removed. The glass portion other than that, that is, the non-modified portion is also removed. However, as described above, since the speed at which the modified portion 21 is removed is faster than that of the surrounding glass, the planned separation portion 22 is separated from the glass substrate, and the modified portion 21 and the surrounding non-modified portion 21 are not formed. A hollow portion 23 including a modified portion can be formed. Then, the planned separation portion 22 can be separated from the glass substrate by bringing the adjacent hollow portions 23 close to each other or joining them.

Further, by applying ultrasonic waves, the following phenomenon progresses, and it is considered that the planned separation portion 22 can be separated in a short time. (I) The outermost surface of the modified portion 21 is removed by reacting with the etching solution 725 to form a recess on the surface of the glass substrate 20. (Ii) When the etching solution 725 is vibrated by ultrasonic waves, the surface tension is reduced and the penetrating power of the etching solution into the recess is improved. Further, when the glass substrate 20 is vibrated by ultrasonic waves, the removed modified portion is quickly separated from the non-modified portion and rapidly diffuses into the entire etching solution. (Iii) As a result, the unreacted etching solution is supplied to the new surface of the modified portion exposed at the bottom of the recess. By repeating the above-mentioned phenomena (i) to (iii), the modified portion is selectively removed, and the planned separation portion 22 can be separated in a short time.

On the other hand, the application of ultrasonic waves may cause damage to the surface of the glass substrate. Accordingly, in one embodiment of the present invention, the dissolved air concentration in the etching solution 725, with the dissolved oxygen concentration in terms D _O conversion, for example, in an alternative dissolved oxygen concentration in terms of pure water (described below), is below 8.0wtppm As a result, it was discovered 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 for achieving the above effect is not limited to this.

By applying ultrasonic waves, cavitation (cavitation) occurs in the etching solution, and a phenomenon occurs in which the surface of the glass substrate is impacted when cavitation collapses. The impact force due to cavitation can cause minute fracture regions on the surface of the glass substrate. By further etching, these minute fracture regions may expand and connect to become rough surfaces and become apparent. In the present application, these minute fracture areas and surface roughness are referred to as damage.

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

Here, unless the etching apparatus 700 is installed in an atmospheric atmosphere and the gas is artificially dissolved in the etching solution 725, the gas dissolved in the etching solution 725 is the atmosphere. Therefore, by controlling the atmospheric concentration dissolved in the etching solution, damage to the glass substrate surface due to cavitation can be suppressed.

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

The gas dissolved in the etching solution is composed of atmospheric components, that is, oxygen, carbon dioxide, nitrogen, and other gases, unless otherwise specified. As an index value that reflects the amount of dissolved air, can be used, for example the dissolved oxygen concentration D _O. Dissolved oxygen concentration D _O generally is advantageous in that it can conveniently measured. However, since it may be technically difficult to measure the dissolved oxygen concentration in the hydrofluoric acid solution more precisely, the dissolved oxygen concentration in one embodiment of the present invention is, for example, in pure water measured by the following procedure. Can be replaced by the measured value of. (Procedure 1) Adjust the dissolved atmospheric concentration of the etching solution under certain conditions. (Procedure 2) Adjust the dissolved atmospheric concentration of pure water under the same conditions as in step 1. (Procedure 3) Measure the dissolved oxygen concentration of pure water using a portable fluorescent dissolved oxygen meter. As a portable fluorescent dissolved oxygen meter, for example, HQ30d manufactured by HACH is used. Measured at this time is "alternative dissolved oxygen concentration in the pure water", the measured value can be used as a "dissolved oxygen concentration D _O" of the etching solution.

Regarding procedure 2, for example, if the method for adjusting the dissolved atmosphere is degassing using a hollow fiber filter and a vacuum pump, the conditions can be met by making the decompression value equal to the decompression value in procedure 1.

In one embodiment of the present invention, preferably, the dissolved air concentration in the etching solution can be below 8.0wtppm in dissolved oxygen concentration D _O conversion, thereby suppressing the occurrence of cavitation, the glass substrate surface It was found that the damage of can be significantly suppressed. Dissolved air concentration, the dissolved oxygen concentration _{D O} conversion, preferably 7.5wtppm or less, more preferably 7.0wtppm or less, still more preferably not more than 6.5Wtppm.

Here, the dissolved air concentration, the reduced gradually from 8.0wtppm in dissolved oxygen concentration _{D O} conversion, the occurrence of cavitation decreases, dissolved air concentration in the vicinity of 4.0wtppm in dissolved oxygen _{D O} terms , The amount of cavitation generated increases again, and a phenomenon that reaches a maximum value may occur. As 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, the surplus atmosphere that does not contribute to cavitation consumes energy, but when the dissolved atmosphere decreases to around 4.0 wtppm in terms of dissolved oxygen concentration, most of the dissolved atmosphere is cavitation. It is thought that this is because there is no surplus atmosphere and energy loss is reduced. Further, when the dissolved atmospheric concentration is reduced, the number of bubbles accumulated in the pores is reduced, the minimum diameter is easily expanded, and the degree of stenosis, which will be described later, is improved.

Thus, the dissolved air concentration in the dissolved oxygen concentration _{D O} conversion, preferably _| D O -4.0 _{|> 0wtppm,} more preferably _| D O -4.0 _| ≧ _0.1wtppm, more preferably | _{D O} -4.0 | ≧ 0.2wtppm, more preferably _| D O -4.0 _| ≧ _0.3wtppm, more preferably _| D O -4.0 _| ≧ _0.4wtppm, more preferably _| D O -4 .0 | ≧ 0.5wtppm, more preferably _| D O -4.0 _| ≧ _0.6wtppm, more preferably _| D O -4.0 _| ≧ _0.7wtppm, more preferably _| D O -4.0 | ≧ 0.8wtppm, more preferably _| satisfy ≧ 0.9wtppm | D O -4.0.

Further, the dissolved air concentration in the dissolved oxygen concentration _{D O} terms generally 0.05wtppm above, in view of the control cost, preferably 0.1wtppm or more.

Next, the frequency range of the ultrasonic wave 735 will be described. The frequency of the ultrasonic wave 735 is not particularly limited, but is preferably 200 kHz or less, more preferably 100 kHz or less, from the viewpoint that the effect of promoting the removal of the modified portion by the ultrasonic wave can be easily obtained. Further, from the viewpoint of suppressing the degree of stenosis described below and significantly improving the selection ratio, it is preferably 40 kHz or less, more preferably less than 40 kHz. Generally, ultrasonic waves of 20 kHz or higher are used.

The hollowed-out portion 23 formed by removing the modified portion 21 and the portion including the non-modified portion around the modified portion 21 after separating the planned separation portion 22 is as shown in FIG. 2 (c). May have a stenosis. The narrowed portion refers to a portion where the inner width of the hollowed portion 23 is smaller than the width of the hollowed portion on the surface of the glass substrate. Such a narrowed portion is formed by the progress of removal of the surrounding glass portion while the modified portion 21 is removed. By reducing the degree of stenosis, the shape of the inner wall of the hollowed out portion 23 can be made closer to vertical, and the time required for hollowed out can be shortened.

Here, the degree of stenosis _{is expressed using the degree of stenosis C 1} (τ). The degree of stenosis C ₁ (τ) is expressed by the following equation (2).

C ₁ (τ) = (D _1- D ₂ ) / t ₁ ... (2)
Here, τ represents the time when the glass substrate 20 is etched for the separation of the planned separation portion 22 (FIG. 3), D ₁ is the width of the hollow portion 23 on the first surface 20 b, and D ₂ is the hollow portion. The minimum value of the inner width of the portion 23 _{is represented by t 1} , and t 1 represents the thickness of the glass substrate 20 after time τ etching.

Further, in order to efficiently etch in a short time and form a hole having a low degree of stenosis, it is necessary to selectively remove the modified portion 21 from the surrounding glass. Here, the selection ratio S (τ) represented by the following formula (3) is defined as an index showing the selectivity of the reforming unit 21 with respect to the glass.

S (τ) = t ₁ / t ₀ ... (3)
Here, τ represents the time when the glass substrate 20 is etched for the separation of the planned separation portion 22, t ₀ is the thickness of the glass substrate 20 before etching, and t ₁ is the time τ after etching the glass substrate. Represents a thickness of 20.

The closer the degree of stenosis C ₁ is to 0, the more the inner wall of the hollow portion 23 has a shape closer to vertical, which is preferable. Further, it is preferable from the viewpoint of production efficiency because the time required for the separation of the planned separation portion 22 can be shortened.

The selection ratio S takes a value in the range of 0 to 1, and the closer S is to 1, the more preferable it is because the modified portion is selectively removed. Further, by increasing the selection ratio S, the amount of removal of the first surface 20b and the second surface 20c until the hollowed portion is formed can be reduced, which is caused by the handling of the glass substrate 20 or cavitation. It is easy to manufacture glass articles with little surface damage by suppressing the phenomenon that latent scratches expand and deepen and become apparent.

The frequency of the ultrasonic wave 735 from the viewpoint that the degree of stenosis C ₁ can be brought close to 0 and the selection ratio S can be brought close to 1, and the above-mentioned phenomenon in which the latent injury expands and deepens and becomes apparent can be suppressed predominantly. Is preferably 200 kHz or less, more preferably 100 kHz or less, still more preferably 40 kHz or less.

On the other hand, the lower the ultrasonic frequency, the larger the size of the cavitation generated, and the larger the shock wave generated when the cavitation collapses. Therefore, when lower frequency ultrasonic waves are used, the effect of suppressing cavitation damage by controlling the dissolved atmosphere in the etching solution becomes remarkable.

Furthermore, it is preferable to modulate the ultrasonic frequency. The method of modulation is not particularly limited, and examples thereof include stepwise switching of frequencies and sweeping. By modulating the frequency, the standing wave position changes in the tank, so etching unevenness can be suppressed, and the cavitation generation position changes, so damage is concentrated at a specific position on the surface of the glass substrate 20. It is preferable because it can prevent this from happening. The frequency modulation method is not particularly limited, but the above effect can be easily obtained by, for example, changing the frequency periodically. On the other hand, ultrasonic waves may be applied at a medium frequency of 40 kHz to 200 kHz at the initial stage of etching, and then switched to a low frequency of 40 kHz or less. By doing so, it is possible to suppress the growth of cracks generated around the modified portion by laser irradiation due to the application of low-frequency ultrasonic waves, and after the tips of the cracks are rounded by etching and the cracks do not grow, the low frequency By switching to, the narrowed portion can be suppressed and the selection ratio can be improved, which is preferable.

Ultrasonic waves are applied for at least a part of the time while the glass substrate is immersed in the etching solution. For example, it may be applied over the entire period, or intermittent operation may be performed by repeating the applied period and the non-applied period. Preferably, the intermittent operation raises large bubbles staying in the liquid that hinders the propagation of ultrasonic waves during the period when the ultrasonic waves are not applied, and collapses at the liquid surface, so that the ultrasonic waves are efficient. Propagation can be maintained.

The output of the ultrasonic wave is preferably 0.5 W / cm ² or more, more preferably set to 0.7 W / cm ² or more. On the other hand, the output of ultrasonic waves is 2 W / cm ² or less. The ultrasonic output may be changed during the etching period. Preferably, the initial etching period is set to low power and then changed to high power. By setting in this way, it is possible to suppress the growth of cracks generated around the modified portion by laser irradiation at the initial stage of etching, and the tips of the cracks are rounded by etching to achieve high output after the cracks do not grow. By changing it, the removal time of the modified part can be shortened.

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

As shown in FIG. 8, in the method for producing 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) and (step S820) forming initial holes in the glass substrate using a laser. and step (laser irradiation step), and (step S830) the glass substrate, the dissolved air is immersed in the etching solution is 8.0wtppm or less dissolved oxygen concentration _{D O} terms, at least part of the period, on the glass substrate ultra It is characterized in that the glass substrate is etched by applying a sound wave.

The 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, the initial hole 91 is formed in place of the modified portion. Here, the initial hole means a fine hole having an opening on at least one surface and extending inside the glass substrate 20. The initial hole 91 may penetrate or may have a closed portion in the middle. When the initial hole is etched, the closed portion is removed and the initial hole is expanded, so that the hole 93 can be formed. The hole may be a through hole or a stop hole (stop hole) in which one side is closed. 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, while when it is desired to form a stop hole, an opening is formed only on one surface. It suffices to form an initial hole having. The laser optical system is designed according to a known technique.

A plurality of initial holes 91 may be formed. It is preferable to form the initial holes at a distance of 10 μm or more because it is possible to prevent the holes from joining each other after etching and the cracks from growing to the adjacent holes.

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

It should be noted that 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 etching solution inside the initial hole 91 and the external etching solution is promoted, and the unreacted etching solution is always supplied to the inside of the initial hole 91. Therefore, the expansion of the initial hole 91 is promoted.

The etching step is carried out until the hole 93 has a desired opening diameter. The hole 93 thus formed may also have a narrowed portion, similar to the hollowed portion 23 described in the first embodiment. The degree of stenosis C ₂ (τ) is defined by the following equation (4).

C ₂ (τ) = (d ₁ − d ₂ ) / t ₁ ... (4)
Here, τ represents the time for etching the glass substrate 20 for forming the hole 93, d ₁ is the opening diameter of the hole 93 on the first surface 20b, and d ₂ is the minimum value of the inner diameter of the hole 93. , T ₁ represents the thickness of the glass substrate 20 after time τ etching.

At this time, the selection ratio S (τ) is defined as the following equation (5). In this case, the selectivity is an indicator of how fast the initial hole expansion has progressed compared to the removal of the glass substrate surface.

S (τ) = t ₁ / t ₀ ... (5)
Here, τ represents the time when the glass substrate 20 is etched to form the holes 93, t ₀ is the thickness of the glass substrate 20 before etching, and t ₁ is the thickness of the glass substrate 20 after time τ etching. Represents.

The closer the degree of stenosis C ₂ is to 0, the more the inner wall of the hole 93 has a shape closer to vertical, which is preferable.

The selection ratio S takes a value in the range of 0 to 1, and the closer S is to 1, the faster the expansion of the initial hole proceeds, so that the time required for forming the hole 93 can be shortened, which is preferable. Further, 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, which is caused by the handling of the glass substrate 20 or cavitation. It is possible to manufacture glass articles with less surface damage by suppressing the phenomenon that latent scratches expand and deepen and become apparent.

Further, one manufacturing method of the present invention can also be applied to cutting a glass substrate. As shown in FIG. 10, when one manufacturing method of the present invention is used for cutting a glass substrate, the degree of stenosis C ₃ _{is a protrusion amount d 3} of the cut surface 101 instead of the formulas (2) and (4). It may be evaluated by using the following equation (6).

C ₃ = d ₃ x 2 / t ₁ ... (6)

<Experiment 1>
In Experiment 1, the dissolved atmospheric concentration of the etching solution and the damage to the glass substrate surface during ultrasonic etching were examined. As a sample, a donut-shaped substrate made of aluminosilicate glass, having a diameter (outer diameter) of 65 mm and a thickness of 0.8 mm and having an opening formed in the center was used.

As the etching apparatus, the same apparatus as the etching apparatus 700 of FIG. 7 was used. The outer tank 710 was filled with pure water as the propagation liquid 715, and the sample was placed directly in the pure water. The etching tank 720 was not used in this experiment. As the ultrasonic generator 730, 60200VS (in the case of frequencies 26kHz, 78kHz, 130kHz) or 60300VS type (in the case of frequencies 38kHz, 100kHz, 160kHz) of the ultrasonic oscillator QUAVA Multi manufactured by Kaijo Co., Ltd. was used.

(Example 1-1)
The detailed experimental procedure is shown below.
(1) The outer tank was filled with ultrapure water in which the dissolved atmospheric concentration was adjusted to a desired dissolved oxygen concentration, and the sample contained in the cassette was fixed at a predetermined position in the outer tank. The ultrasonic oscillator was set to a desired frequency, and ultrasonic waves having a maximum output of 600 w and a frequency of 26 kHz were irradiated for 10 minutes to impart minute damage due to cavitation to the sample surface. The dissolved air concentration, 1.0Wtppm in dissolved oxygen concentration _{D O} conversion was 2.0wtppm, 3.0wtppm, 4.0wtppm, 5.0wtppm, 6.0wtppm, 7.0wtppm, varied with 8.0Wtppm. The dissolved oxygen concentration in pure water was adjusted by degassing with a hollow fiber membrane and degassing with a vacuum pump.
(2) After the above-mentioned minute damage is applied, each sample is immersed in 2 wt% hydrofluoric acid and etched until the plate thickness is reduced by 4 μm so that the applied minute damage can be easily detected. Enlarged.
(3) Each sample was subjected to ultrapure water ultrasonic cleaning and IPA (isopropyl alcohol) vapor drying.
(4) The damage of each sample was evaluated using a laser scattering type defect inspection machine RSI-65200 manufactured by System Seiko Co., Ltd. The detection sensitivity was 0.12 μm, and the number of defects detected was counted.

(Example 1-2 to Example 1-6)
In the same manner as in Example 1-1, the dissolved atmospheric concentration was changed to inflict minute damage and the damage was expanded, except that the frequencies were 38 kHz, 78 kHz, 100 kHz, 130 kHz, and 160 kHz, respectively. The number of defects was counted.

According to the results of Experiment 1, as the dissolved oxygen concentration Do decreased, the number of defects on the surface of the glass substrate tended to decrease. In addition, when the dissolved oxygen concentration Do was around 4.0 wtppm, the number of defects tended to increase temporarily. As a representative, FIG. 11A shows the result of Example 1-1 (frequency 26 Hz), and FIG. 11B shows the result of Example 1-3 (frequency 78 Hz).

<Experiment 2>
In Experiment 2, the effect of the ultrasonic frequency during etching on the selectivity S and the degree of stenosis C of the formed holes was examined.

(Examples 2-1 to 2-7)
In Examples 2-1 to 2-7, experiments were carried out using glass having composition 1 (aluminosilicate glass). First, the glass substrate was irradiated with a laser. As the laser irradiation device, a device having the same configuration as that shown in FIG. 3 was used. The irradiated laser was a burst pulse laser having a wavelength of 1064 mm, an output of 35.5 W, and an oscillation frequency of 75 kHz, and fine holes were formed in the glass substrate by the above steps.

Next, the glass substrate was etched. As the etching apparatus, the same apparatus as the etching apparatus 700 of FIG. 8 was used. The outer tank 710 was filled with pure water as the propagation liquid 715, and the etching tank 720 was filled with the etching liquid 725. At this time, the etching solution contained 2.3 wt% of HF and 12 wt% of HNO _3, and the temperature of the etching solution was 16 ° C. A sample housed in a cassette was placed in the etching tank 720, and an ultrasonic generator 730 similar to that used in Experiment 1 was used. In each of Examples 2-1 to 2-7, an experiment was carried out by applying ultrasonic waves having the frequencies shown in Table 1. In each example, the etching was carried out until the holes penetrated and the ultrasonic waves were continuously applied during the etching period.

(Example 2-8 to Example 2-14)
In Examples 2-8 to 2-14, the experiment was carried out by applying ultrasonic waves having different frequencies in the same manner as in Examples 2-1 to 2-7, except that the glass of composition 2 (soda-lime glass) was used. went. Table 1 also shows the frequencies of the ultrasonic waves used in Examples 2-8 to 2-14.

In all of Examples 2-1 to 2-14, holes were formed in the glass substrate. The diameter of the formed hole is d ₁ , the minimum diameter inside the hole is d ₂ , the thickness of the glass substrate before _{etching is t 0} , the thickness of the glass substrate _{after etching is t 1} , and the cut surface after etching. The degree of squeezing C = (d ₁ − d ₂ ) / t ₁ and the selection ratio S = t ₁ / t ₀ are summarized in Table 1 below. Further, FIG. 12A graphically shows the stenosis degree C and the selection ratio S of Examples 2-1 to 2-7, and FIG. 12A shows the stenosis degree C and the selection ratio S of Examples 2-8 to 2-14. Shown in a graph.

As shown in Table 1, FIG. 12A, and FIG. 12B, it can be seen that the degree of stenosis C is suppressed and the selection ratio S is improved by reducing the frequency of the ultrasonic waves.

This application claims priority based on Japanese Patent Application No. 2019-149982 filed with the Japan Patent Office on August 19, 2019, the entire contents of which are incorporated herein by reference.

20 Glass substrate 20b First surface of glass substrate 20c Second surface of glass substrate 21 Modified part 22 Scheduled separation part 23 Hollowed part 24 Modified part before etching or boundary line between initial hole and glass part 25 Before etching Glass substrate surface 30 Contour line 91 Initial hole 93 Hole 101 Cut surface d ₁ Opening diameter on the first surface of _{the hole of the glass substrate d 2} Minimum diameter inside the hole of the _{glass substrate d 3} Projection amount of the cut surface of the glass substrate D ₁ Width on the first surface of the _{hollowed out part D 2} Minimum width inside the hollowed out part t ₀ Thickness of the glass substrate before the _{etching process t 1} Thickness of the glass substrate after the etching process 400 Laser irradiation device 450 Stage 460 Laser oscillator 465 Laser beam 470 Beam adjustment 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 Propagation liquid 720 Etching tank 725 Etching liquid 730 Ultrasonic generator 735 Ultrasonic

Claims

A step of preparing a glass substrate having a first surface and a second surface facing each other, and
A step of forming an initial hole or a modified portion on the glass substrate using a laser, and
The glass substrate, the dissolved air concentration is immersed in the etching solution is 8.0wtppm or less dissolved oxygen concentration D O terms, at least part of the period, by applying ultrasonic waves to the glass substrate, the glass substrate Equipped with an etching process,
Manufacturing method for glass articles.
The dissolved oxygen concentration D O satisfies the expression (1), process for producing a glass article according to claim 1.
| D O -4.0 |> 0wtppm ··· (1)
The method for manufacturing a glass article according to claim 1 or 2, wherein the frequency of the ultrasonic wave is 200 kHz or less.
The method for manufacturing a glass article according to any one of claims 1 to 3, wherein the frequency of the ultrasonic wave is less than 40 kHz.