TWI628150B - Glass processing method - Google Patents

Abstract

A glass processing method comprising the steps of: forming a through hole 11 in a glass substrate 10 using laser light; and performing a wet etching process on the through hole 11 using an etching liquid 34. The etching solution 34 contains hydrofluoric acid and a first liquid containing an acid having a larger molecular size than hydrofluoric acid. The concentration of hydrofluoric acid is 4% by weight or less. The concentration of the first liquid is higher than the concentration of hydrofluoric acid.

Description

Glass processing method

The present invention relates to a method of processing glass using laser light.

The glass substrate having a plurality of minute through holes can be used, for example, in a substrate for a printing head of an ink jet method, or a double-sided wiring board. The through-holes are usually formed by using laser light (Japanese Patent Laid-Open Publication No. 2000-61667, Japanese Patent No. 4672689).

The portion of the glass that is in contact with the laser light (the metamorphic layer) has heat during processing and is cracked (microcracked) due to strain caused by thermal stress. Thereby, the characteristics (function) of the glass substrate are lowered, or the glass substrate is easily broken.

The present invention provides a method of processing glass which can improve the characteristics of a glass substrate having through-holes.

A method of processing a glass according to an aspect of the present invention includes a step of forming a through hole in a glass substrate using laser light, and a step of wet etching the through hole using an etching solution. The aforementioned etching liquid package A first liquid containing hydrofluoric acid and an acid having a larger molecular size than the hydrofluoric acid. The concentration of the hydrofluoric acid is 4% by weight or less. The concentration of the first liquid is higher than the concentration of the hydrofluoric acid.

According to the present invention, it is possible to provide a method of processing glass which can improve the characteristics of a glass substrate having through-holes.

10‧‧‧ glass substrate

11‧‧‧through holes

12‧‧‧ crack

20‧‧‧ Laser processing equipment

21‧‧‧Laser Vibrator

22‧‧‧Optical system

23‧‧‧Mirror

24‧‧‧ collecting lens

25‧‧‧Seat

26‧‧‧Laser light

30‧‧‧ Wet etching device

31‧‧‧ etching treatment tank

32‧‧‧Supersonic generator

33‧‧‧ Keeping institutions

34‧‧‧etching solution

S100, S101‧‧‧ steps

D1, D2‧‧‧ diameter

Fig. 1 is a flow chart showing a method of processing a glass substrate according to an embodiment.

Fig. 2 is a schematic view showing an example of a laser processing apparatus.

Fig. 3 is a view showing a glass substrate on which a plurality of through holes are formed.

Fig. 4 is a schematic view of a wet etching apparatus used in the wet etching step.

Fig. 5 is a cross-sectional view showing an example of a through hole after wet etching.

Fig. 6 is a photograph showing an example of a through hole before wet etching.

Fig. 7 is a photograph showing an example of a through hole after wet etching.

Fig. 8 is a schematic view showing the principle of wet etching in the embodiment.

Fig. 9 is a graph showing the etching rate of wet etching in the present embodiment.

Fig. 10 is a graph illustrating bubbles generated by ultrasonic waves.

Fig. 11 is a schematic view showing the principle of wet etching of a comparative example.

FIG. 12 is a photograph showing an example of a through hole after wet etching in a comparative example.

[Formation of the Invention]

Hereinafter, the embodiment will be described with reference to the drawings. However, the drawings are schematic or conceptual drawings, and the dimensions, ratios, and the like of the respective drawings are not necessarily limited to the same as the actual ones. Further, even when the same portions are indicated between the drawings, there are cases in which the dimensional relationships and the ratios are different from each other. In particular, the following embodiments are exemplified by means and methods for embodying the technical idea of the present invention, and the technical idea of the present invention is not limited by the shape, structure, arrangement, and the like of the components. In the following description, elements having the same functions and configurations are denoted by the same reference numerals, and the description thereof will be repeated only when necessary.

Fig. 1 is a flow chart for explaining a method of processing a glass substrate of the embodiment. First, the glass substrate 10 is prepared. The thickness of the glass substrate 10 is, for example, about 0.1 to 1.5 mm. In the present specification, "~" indicating a numerical range means a range including values before and after.

Next, as shown in FIG. 1, one or a plurality of through holes are formed in the glass substrate 10 using laser light (step S100). FIG. 2 is a schematic view showing an example of the laser processing apparatus 20. The laser processing apparatus 20 includes a laser vibrator 21, an optical system 22 (including a mirror 23 and a collecting lens 24), a seat 25, and the like.

The seat 25 holds the glass substrate 10. The pedestal 25 adsorbs or fixes the glass substrate 10. As the adsorption fixation, for example, vacuum adsorption or electrostatic adsorption can be used. The seat 25 may have a function of moving the glass substrate 10 horizontally, and for example, may be constituted by an X-Y seat. In this case, the seat (X-Y seat) 25 can utilize the two axes using the motor. The moving mechanism (not shown) moves widely.

The laser vibrator 21 emits the laser light 26. As the laser, an ultraviolet (ultraviolet) laser of an ultrashort wave pulse (for example, a nanosecond pulse) can be used. As the UV laser, an excimer laser, an individual laser, or the like can be used. As the individual laser, for example, a YAG laser (Nd:YAG laser) using a medium doped with Nd (yttrium) in yttrium-aluminum-garnet crystals can be cited.

The mirror 23 reflects the laser light 26 from the laser vibrator 21 to the side of the glass substrate 10. The collecting lens 24 receives the laser light 26 from the mirror 23. Then, the collecting lens 24 collects and irradiates the laser light 26 to the glass substrate 10 held by the seat 25. The collecting lens 24 can be formed by a plurality of lenses. The light collecting position of the laser light 26 is, for example, the main surface of the glass substrate 10 on the side of the laser light source or its vicinity. The glass substrate 10 is partially heated by the laser light 26, and the heating portion is removed, and the through hole 11 is formed in the glass substrate 10. The through hole 11 is also referred to as a through glass passage (TGV: Through Glass Via).

FIG. 3 is a view for explaining the glass substrate 10 in which a plurality of through holes 11 are formed. For example, as shown in FIG. 3, the glass substrate 10 is subjected to a plurality of through hole forming steps, and a plurality of through holes 11 are formed in the glass substrate 10. The diameter D1 of the through hole 11 is, for example, about 10 to 50 μm. The diameter of the through hole described in the present specification is, for example, the size of the upper surface of the glass substrate. The glass substrate 10 of FIG. 3 is an inkjet type print head substrate, a double-sided wiring board, a multi-chip module (MCM) which can be used to assemble a plurality of IC chips in one package, or can realize a system level in a single package. An example of a glass adapter plate (intermediate substrate) that functions as a system-in-package (SiP).

Here, in the step of forming the through hole using the laser light, the vicinity of the through hole 11 is formed on the upper surface side and the bottom surface side of the glass substrate 10. A number of cracks (micro-cracks) 12 are produced. That is, the step of forming the through holes using the UV laser light is thermally processed, so that cracks caused by thermal strain are widely generated in the periphery of the processed portion.

Then, as shown in FIG. 1, wet etching is performed while applying ultrasonic vibration (step S101). The wet etching step is performed, for example, for about 20 minutes. 4 is a schematic view of a wet etching apparatus 30 used in the wet etching step.

The wet etching apparatus 30 includes an etching treatment tank 31, an ultrasonic generation device 32, and a holding mechanism 33. The etching liquid 34 is supplied into the etching treatment tank 31. The holding mechanism 33 is movable, and for example, a plurality of glass substrates 10 can be held. The holding mechanism 33 is disposed at a position where the glass substrate 10 can be immersed in the etching liquid 34. As a method of fixing the glass substrate 10, for example, the glass substrate 10 may be attached to the holding mechanism 33, and the holding mechanism 33 may be provided with a mechanism for holding the glass substrate 10.

The ultrasonic generating device 32 is provided in the etching treatment tank 31 so as to be immersed in the etching liquid 34. The ultrasonic generating device 32 generates ultrasonic waves to cause ultrasonic vibration of the etching liquid 34. By this ultrasonic vibration, a plurality of bubbles are generated in the etching liquid 34, and cavitation is caused in the etching liquid 34. Thereby, the through hole 11 of the glass substrate 10 is etched.

Next, the etching liquid 34 used in the wet etching step will be described. The etching solution 34 contains hydrofluoric acid (HF), sulfuric acid (H ₂ SO ₄ ), and water (H ₂ O). The concentration of hydrofluoric acid (HF) is greater than 0 and is 4% by weight or less. More desirably, the concentration of hydrofluoric acid is 1.5% by weight or less. The concentration of sulfuric acid is higher than the concentration of hydrofluoric acid and is 10% by weight or more and 90% by weight or less. More preferably, the concentration of sulfuric acid is 40% by weight or more and 60% by weight or less. Specifically, the etching liquid 34 contains about 0.5% by weight of hydrofluoric acid, about 60.0% by weight of sulfuric acid, and about 39.5% by weight of water.

The glass substrate 10 has a main component of SiO ₂ (40 to 70%), and the second most component is Al ₂ O ₃ (5 to 20%).

In the glass substrate 10, hydrofluoric acid (HF) contained in the etching liquid 34 reacts with three types (1) to (3) shown below.

SiO ₂ +4HF → SiF ₄ +2H ₂ O...(1)

SiO ₂ +6HF → H ₂ SiF ₆ +2H ₂ O...(2)

Al ₂ O ₃ +6HF → 2AlF ₃ +3H ₂ O...(3)

FIG. 5 is a cross-sectional view showing an example of the through hole 11 after the wet etching. By the wet etching step, the crack is etched, and the through hole 11 having almost no cracks can be formed. The diameter D2 of the through hole 11 after the wet etching is, for example, 50 to 150 μm.

FIG. 6 is a photograph showing an example of the through hole 11 before wet etching. The photograph of Fig. 6 was taken using a scanning electron microscope (Scanning Electron Microscopy: SEM). A plurality of cracks are formed around the through hole 11 of Fig. 6 . The through hole 11 of Fig. 6 has a diameter of about 100 μm.

FIG. 7 is a photograph showing an example of the through hole 11 after the wet etching. There is almost no crack around the through hole 11 of Fig. 7, that is, the crack can be completely removed by performing the wet etching of this embodiment.

Fig. 8 is a schematic view showing the principle of wet etching in the present embodiment. The left side of Fig. 8 is a plan view before wet etching, and the right side of Fig. 8 is a plan view after wet etching.

Hydrofluoric acid (HF) has a small viscosity (viscosity coefficient), a small surface tension, and a small molecular size, so it is easy to intrude into cracks. On the other hand, compared with hydrofluoric acid, sulfuric acid (H ₂ SO ₄ ) has a large viscosity, a large surface tension, and a large molecular size, so that it is difficult to intrude into the crack. Further, the acid to be mixed with hydrofluoric acid is not limited to sulfuric acid, and an acid having a viscosity higher than that of hydrofluoric acid, a large surface tension, and/or a large molecular size can be used. Examples of the acid satisfying such conditions include acetic acid, phosphoric acid, or nitric acid. Further, a liquid other than an acid which satisfies the above conditions, such as glycerin or the like, may also be used.

The etching liquid 34 of the present embodiment has a sulfuric acid concentration higher than that of hydrofluoric acid, and the etching liquid 34 has a high viscosity. Therefore, it becomes difficult for the etching liquid 34 to intrude into the crack, and it is possible to suppress the etching progress in the crack.

As a principle of etching, hydrofluoric acid is ionized, and fluorine (F) ions become a main body of a dissolved glass substrate. However, in order to carry out the dissolution of the glass substrate, assistance of hydrogen (H) ions is required. Hydrogen ions assist in the dissolution of the glass substrate by lowering the potential of hydrogen.

In the present embodiment, the concentration of hydrofluoric acid (for example, 0.5% by weight) is lowered. In this case, in the case of only hydrofluoric acid, since the amount of dissolved hydrogen ions in the auxiliary glass substrate is small, etching of the glass substrate is difficult. However, in the present embodiment, the etching liquid contains sulfuric acid, and the pH of the etching liquid is lowered by the hydrogen ions contained in the sulfuric acid, thereby facilitating the dissolution of the glass substrate.

According to such a principle, as shown in FIG. 8, the etching in the crack 12 is not promoted, and the entire through hole 11 is uniformly etched. Thereby, the etching of the through hole 11 is performed without the crack 12 being expanded, and the etching is performed so that the entire through hole 11 is enlarged. As a result, almost before wet etching The crack 12 is removed. In addition, when the concentration of the hydrofluoric acid is 4% by weight or more, even when a component other than hydrofluoric acid is added to the etching liquid, the etching proceeds in the crack. Thus, in the present embodiment, the concentration of hydrofluoric acid is set to 4% by weight or less.

Further, ultrasonic waves are generated by the ultrasonic generating device 32 to cause holes in the etching liquid 34. The diameter of the bubble generated by the cavity is desirably smaller than the diameter of the through hole and larger than the width of the crack. Thereby, the air bubbles generated by the holes intrude into the through holes 11, but it becomes difficult to intrude into the cracks 12. Thereby, etching of the through holes 11 is promoted, and etching in the cracks 12 can be suppressed. For example, when the diameter of the through hole 11 is 100 μm, the diameter of the bubble is preferably 80 μm or less. The frequency of the ultrasonic wave at this time is set to 28 kHz or more.

Fig. 9 is a graph showing the etching rate of wet etching in the present embodiment. The horizontal axis of Fig. 9 represents the processing time (minutes), and the vertical axis of Fig. 9 represents the etching amount (μm). The etching solution used in Fig. 9 contained 0.5% by weight of hydrofluoric acid, 69.3% by weight of sulfuric acid, and 30.2% by weight of water. The pH of this etchant is less than one. The wet etching of this embodiment can achieve a high etching rate.

Fig. 10 is a graph illustrating bubbles generated by ultrasonic waves. The horizontal axis of Fig. 10 represents the frequency (kHz) of the ultrasonic wave, and the vertical axis of Fig. 10 represents the diameter (μm) of the bubble. As shown in FIG. 10, by setting the frequency of the ultrasonic wave to 28 kHz or more, it is possible to form a bubble having a diameter of 80 μm or less. Thereby, etching of the through holes 11 is promoted, and etching in the cracks 12 can be suppressed.

(Comparative example)

Next, a description will be given of a comparative example. Fig. 11 is a schematic view showing the principle of wet etching of a comparative example. The left side of Fig. 11 is a plan view before wet etching, and the right side of Fig. 11 is a plan view after wet etching.

The etching liquid of the comparative example contains, for example, about 4% by weight of hydrofluoric acid and about 96% by weight of water. That is, the etching liquid of the comparative example does not contain an acid other than hydrofluoric acid.

In the comparative example, hydrofluoric acid (HF) was ionized, and fluorine (F) ions dissolved glass. Hydrogen (H) ions reduce the pH of the etchant and aid in the dissolution of the glass produced by the fluoride ions. In the etching solution of the comparative example, since the viscosity and the surface tension were low, the etching liquid penetrated into the crack. Thereby, the through holes and the cracks are etched in an isotropic manner, and the cracks are enlarged. That is, the wet etching step of the comparative example could not remove the crack.

FIG. 12 is a photograph showing an example of the through hole 11 after wet etching in the comparative example. As shown in Fig. 12, the crack of the comparative example was enlarged, and the crack could not be completely removed.

In Fig. 9, a graph of a comparative example is also described. The etching solution of the comparative example used in FIG. 9 contains about 0.5% by weight of hydrofluoric acid and about 9.5% by weight of water. The pH of this etching solution is about 3. Compared with the present embodiment, the comparative example has a low etching rate.

(effect)

According to the above-described embodiment, in the present embodiment, first, the through hole 11 is formed in the glass substrate 10 by using the laser light 26. Then, the through hole 11 is wet-etched using the etching liquid 34. The etching solution 34 contains hydrofluoric acid, sulfuric acid having a molecular size larger than that of hydrofluoric acid, and water. The concentration of hydrofluoric acid is 4% by weight or less. The concentration of sulfuric acid is higher than the concentration of hydrofluoric acid to 10 The weight% or more is 90% by weight or less.

Thus, according to the present invention, the crack 12 formed around the through hole 11 can be removed or almost removed. Thereby, it is possible to suppress deterioration in characteristics (function) of the glass substrate 10 having a plurality of through holes 11. Further, it is possible to suppress cracking of the glass substrate 10 due to the cracks 12.

Further, by using the etching liquid 34 of the present embodiment, the etching rate can be increased. Thereby, the wet etching step can be shortened, so that the manufacturing cost can be reduced.

Further, ultrasonic waves are applied to the etching liquid 34 to cause voids in the etching liquid 34. Further, in order to make it difficult for the bubbles generated by the holes to intrude into the crack 12, the frequency of the ultrasonic waves is set to 28 kHz or more. Thereby, etching of the through holes 11 is promoted, and etching in the cracks 12 can be suppressed. As a result, the crack 12 can be removed. Further, the etching rate can be further increased by the holes.

The present invention is not limited to the above-described embodiments, and constituent elements may be modified and embodied without departing from the spirit and scope of the invention. Further, the above embodiment includes various stages of the invention, and various inventions can be configured by an appropriate combination of a plurality of constituent elements disclosed in one embodiment or an appropriate combination of constituent elements disclosed in different embodiments. . For example, even if several constituent elements are removed from all the constituent elements disclosed in the embodiment, the problem to be solved by the invention can be solved, and when the effects of the invention can be obtained, the embodiment in which these constituent elements are removed can be invented. The form is drawn out.

Claims (6)

A method for processing glass comprising: a step of forming a through hole in a glass substrate using laser light; and a step of wet etching the through hole using an etching solution containing hydrofluoric acid and a first liquid The concentration of the hydrofluoric acid is 1.5% by weight or less, and the first liquid is sulfuric acid, acetic acid, phosphoric acid, nitric acid, or glycerin, and the concentration of the first liquid is 10% by weight or more and 90% by weight or less. A method of processing a glass according to claim 1, wherein the first liquid is sulfuric acid. The method for processing a glass according to claim 1, wherein the concentration of the first liquid is 40% by weight or more and 60% by weight or less. A method of processing a glass according to claim 1, wherein the pH of the etching solution is less than 1. A method of processing a glass according to claim 1, further comprising the step of applying an ultrasonic wave to the etching solution. A method of processing a glass according to claim 5, wherein the frequency of the ultrasonic wave is 28 kHz or more.