JP2000281383A - Etching liquid for glass, etching method and production of microlens substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prepare an etching liquid capable of making an etching surface smooth. SOLUTION: The etching liquid contains hydrofluoric acid, water and a bubble removing agent (glycerol, ethylene glycol or isopropyl alcohol). The bubble removing agent has an effect to remove bubbles (H2) fixed on the surface of the glass. These bubbles are formed by the reaction of hydrofluoric acid with the glass. The suitable concentration of the bubble removing liquid is in the range of 2 to 50 wt.%, and the bubble removing liquid is preferably used at a temp. of 5 to 60 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an etching solution for glass used for etching glass, an etching method, and a method for manufacturing a microlens substrate.

[0002]

2. Description of the Related Art A projection display device (liquid crystal projector) for projecting an image on a screen is known. In such a projection display device, a liquid crystal panel (liquid crystal optical shutter) is mainly used for image formation.

[0003] Among liquid crystal panels, there are known liquid crystal panels provided with a large number of microlenses at positions corresponding to respective pixels in order to increase the transmittance and utilization efficiency of light transmitted through the liquid crystal panel. This allows the liquid crystal panel to form a bright image with a relatively small amount of light.

[0004] The microlens is usually formed on a microlens substrate provided in a liquid crystal panel.

[0005] As a method of forming such a micro lens, for example, a base material is pressed through a resin layer onto a mold to which a release agent has been applied in advance, and the resin is cured in this state. There is known a method of forming a microlens base material integrally having a microlens onto which the shape of the microlens is transferred (transfer method). Also, a method of providing a convex resist corresponding to the shape of the microlens on the substrate surface and performing dry etching to transfer the shape of the resist onto the substrate and form a convex microlens on the substrate It has been known.

Further, a recess corresponding to the shape of the microlens is formed on the substrate by wet etching,
A method of forming a microlens by filling a predetermined material into such a concave portion is known.

Incidentally, in order to obtain excellent optical characteristics, it is preferable that the shape of the microlens is closer to a more ideal lens shape. For this reason, when forming a microlens by forming a concave portion on the substrate, it is necessary to make the shape of the concave portion closer to an ideal lens shape. Further, it is necessary to make the surface of the concave portion smoother.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide an etching solution for glass capable of smoothing an etching surface, an etching method using such an etching solution, and a method for manufacturing a microlens substrate. Is to provide.

[0009]

This and other objects are achieved by the present invention which is defined below as (1) to (12).

(1) A glass etching solution for etching glass, comprising: hydrofluoric acid, water, and a bubble release agent for promoting release of bubbles generated on the glass surface. For etching solution.

(2) The etching solution for glass according to (1), wherein the bubble releasing agent is a water-soluble substance having an alcoholic hydroxyl group.

(3) The etching solution for glass according to (2), wherein the bubble releasing agent is a polyhydric alcohol.

(4) The bubble release agent is glycerin,
The etching solution for glass according to the above (2), which contains at least one of ethylene glycol and isopropyl alcohol.

(5) The concentration of the bubble release agent is 2 to 50.
The etching solution for glass according to any one of the above (1) to (4), which is a percentage by weight.

(6) The etching solution for glass according to any one of the above (1) to (5), wherein the concentration of the hydrofluoric acid is 1 to 40% by weight.

(7) When the concentration of the hydrofluoric acid is C ₁ and the concentration of the bubble releasing agent is C ₂ , C ₁ : C ₂ is 10
The glass etchant according to any one of the above (1) to (6), wherein the ratio is 0: 5 to 100: 2000.

(8) The glass etching solution according to any one of the above (1) to (7), wherein the pH is 5 or less.

(9) An etching method characterized in that etching is performed by bringing the glass etching solution according to any one of the above (1) to (8) into contact with a glass substrate.

(10) Forming a mask layer made of silicon or silicon nitride on a glass substrate,
The etching method according to the above (9), wherein the glass etching solution is brought into contact with the glass substrate.

(11) The etching method according to the above (9) or (10), wherein the etching is performed under a temperature condition of 5 to 60 ° C.

(12) Forming a large number of recesses in a glass substrate by the etching method according to any one of the above (9) to (11), and filling the recesses with a material having a higher refractive index than the glass substrate. A method for producing a microlens substrate.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on preferred embodiments.

The etching solution (etching solution for glass) of the present invention etches a glass, and comprises hydrofluoric acid (HF), water,
And a bubble release agent for promoting the release of bubbles from the glass surface.

The first feature of the etching solution of the present invention is that it contains hydrofluoric acid. Hydrofluoric acid is a main component for etching glass, whereby the etching solution of the present invention can etch glass. Therefore, by appropriately selecting the concentration of hydrofluoric acid, the etching rate of the glass substrate, that is, the etching speed can be adjusted. Note that water functions, for example, as a solvent.

Further, the etching liquid of the present invention is characterized in that it contains a bubble releasing agent (wetting improver) for promoting the release of bubbles on the surface of the glass substrate.

When etching glass with hydrofluoric acid, during etching, the hydrofluoric acid reacts with the glass to generate, for example, hydrogen gas (H ₂ ). This hydrogen gas becomes bubbles,
It may adhere to the etched portion of the glass, that is, the etched portion, and may remain. In addition, bubbles may adhere to the etched portion of the glass substrate due to various factors.

In the portion where such air bubbles adhere, the air bubbles prevent the etching solution from sufficiently contacting the glass, thereby inhibiting smooth etching. For this reason, there is a difference in the degree to which the glass is etched between the portion where the bubbles are attached and the portion where the bubbles are not attached. As a result, the surface of the etched area,
That is, the etched surface becomes rough.

The present inventor has conducted intensive studies on the composition of the etching solution and the like in order to smooth the etched surface. As a result, by adding a bubble releasing agent to the etching solution,
It has been discovered that the wettability of the etchant on the glass surface is improved, and that bubbles can be smoothly removed from the glass surface. That is, the present inventor can remove bubbles from the surface of the glass at the time of etching by including the bubble removing agent in the etching solution, and thereby make the etching surface very smooth. I found that I can do it.

As a result of repeated experiments and studies on various substances from various angles, the present inventors have found various substances as bubble releasing agents. Among them, excellent bubble releasing agents are listed, for example, glycerin, ethylene glycol, isopropyl alcohol, t-butyl alcohol, sec.
Alcohols such as -butyl alcohol, isobutyl alcohol, n-butyl alcohol, n-propyl alcohol, ethyl alcohol, methyl alcohol, 1,2-propylene glycol, 1,3-propane glycol, acetone, diethyl ketone, ethyl methyl ketone, etc. Ketones, aldehydes such as formaldehyde, acetaldehyde and propionaldehyde, dihydroxyacetone and glyceraldehyde.

Among these, it is particularly preferable that the bubble releasing agent is a water-soluble substance having an alcoholic hydroxyl group. The present inventor has discovered that among the various bubble releasing agents described above, those having an alcoholic hydroxyl group are particularly excellent in the bubble releasing ability. In addition, when the bubble releasing agent is water-soluble, it becomes easy to add the bubble releasing agent to the etching solution and make it contain.

Examples of such a water-soluble substance having an alcoholic hydroxyl group include glycerin, ethylene glycol, isopropyl alcohol, t-butyl alcohol, sec-butyl alcohol, isobutyl alcohol, n-butyl alcohol, and n-propyl alcohol. ,
Examples include ethyl alcohol, methyl alcohol, 1,2-propylene glycol, 1,3-propane glycol, dihydroxyacetone, and glyceraldehyde.

Further, among them, as the bubble release agent,
Polyhydric alcohols are best. Etching is often performed under some heating conditions (for example, 25 ° C. or higher). In such a case, the monohydric alcohol may be easily volatilized. On the other hand, polyhydric alcohols are relatively hard to volatilize. Therefore, when a polyhydric alcohol is used as the bubble releasing agent, the bubble releasing agent volatilizes during the etching, and the concentration of the bubble releasing agent is prevented from decreasing. This makes it possible to very suitably remove bubbles on the glass surface until the final stage of the etching process.

Examples of the polyhydric alcohol include glycerin, ethylene glycol, 1,2-propylene glycol, 1,3-propane glycol and the like.

Among the various bubble removing agents described above, glycerin, ethylene glycol or isopropyl alcohol is extremely excellent as a bubble removing agent, considering the bubble removing ability, volatility, handleability, safety and the like in total. It has characteristics.

The present inventor also conducted experiments and studies on a suitable concentration of the bubble releasing agent in the etching solution. As a result, the present inventor has found 2 to 50% by weight as a suitable concentration range of the bubble release agent. Further, it has been found that even within such a range, 5 to 30% by weight is optimal.
That is, if the concentration of the bubble releasing agent is less than the lower limit of this range, the bubble removing ability of the etching solution is reduced, and the etched surface may not be smooth depending on the concentration of hydrofluoric acid, the glass material, and the like. On the other hand, if the concentration of the bubble release agent exceeds the upper limit of this range, the etching efficiency may be reduced depending on the concentration of hydrofluoric acid, the glass material, and the like.

In the etching solution of the present invention, the concentration of hydrofluoric acid is from 1 to 40 from the viewpoint of suitably etching glass.
%, Preferably about 5 to 25% by weight. If the concentration of hydrofluoric acid exceeds the upper limit of this range, it may be difficult to make the etching solution contain a sufficient amount of the bubble removing agent. In addition, the etching speed becomes too fast, and therefore, depending on the type and content of the bubble removing agent, bubbles generated during etching cannot be completely removed, the bubbles remain on the glass surface, and the etching surface is smooth. May not be. On the other hand, if the concentration of hydrofluoric acid is less than the lower limit of this range, the material, type, and
Depending on the type and content of the bubble releasing agent, the etching rate may be too slow, and the etching efficiency may be reduced.

The present inventor has also found a preferred content ratio between hydrofluoric acid and a bubble release agent. That is, the content ratio of hydrofluoric acid to the bubble releasing agent is such that the concentration of hydrofluoric acid in the etching solution is C ₁ (% by weight) and the concentration of the bubble removing agent is C ₂ (% by weight).
Where C ₁ : C ₂ is 100: 5 to 100: 20
It is preferably about 00, and 100: 20 to 10
More preferably, the ratio is about 0: 500. When the content ratio of hydrofluoric acid to the bubble releasing agent is within this range, the etched surface can be made smoother.

The pH of the etching solution is preferably 5 or less, more preferably 2.5 or less. When the pH of the etching solution is equal to or lower than this value, the glass can be more suitably etched.

The etching solution of the present invention can suitably etch various glass materials such as quartz glass, soda lime glass, alkali aluminosilicate glass, and multi-component alkali-free glass.

The etching solution of the present invention may contain a plurality of the above-mentioned bubble release agents.

The etching solution of the present invention may contain, in addition to the above components, other additives, for example, a catalyst (etching accelerator) such as ammonium fluoride, a surfactant, and the like.

Hereinafter, a method of using the etching solution of the present invention,
That is, the etching method using the etching solution of the present invention will be described by taking as an example a case where a large number of recesses are formed in a glass substrate to manufacture a glass substrate with a recess used for a microlens substrate, for example.

First, as shown in FIG. 1, a glass substrate 5 of, for example, vermilion processing is prepared as a base material. As the glass substrate 5, a glass substrate having a uniform thickness and having no bending or scratch is preferably used. Further, it is preferable that the surface of the glass substrate 5 is cleaned by washing or the like.

<1> First, FIG.
As shown in (a), a mask layer 6 is formed. At the same time, a back surface protection layer 69 is formed on the back surface of the glass substrate 5 (the surface opposite to the surface on which the mask layer 6 is formed).

As a constituent material of the mask layer 6, for example,
Silicon such as polycrystalline silicon (polysilicon) and amorphous silicon, and silicon nitride such as silicon nitride are preferably used.

The present inventor has found that the above-mentioned etching solution is very difficult to etch such a mask material, that is, the etching rate is very low for such a material. Therefore, when the mask layer 6 is formed of such a material and the glass substrate 5 is etched using the etching solution of the present invention, the glass substrate 5 can be selectively etched. Therefore, when the etching solution of the present invention is used, when the mask layer 6 is made of such a material, the glass substrate 5 can be protected with a relatively small thickness as described later.

Among the materials described above, the material constituting the mask layer 6 is preferably polycrystalline silicon. When the mask layer 6 is made of polycrystalline silicon, a dense layer can be formed on the surface of the glass substrate 5. Therefore, defects such as pinholes are less likely to occur in the mask layer 6. In addition, polycrystalline silicon has high adhesion to glass. For this reason,
When wet etching is performed using the etching solution of the present invention, the etching solution hardly enters an unnecessary portion between the glass substrate 5 and the mask layer 6.

The thickness of the mask layer 6 is not particularly limited, but is preferably about 0.01 to 10 μm, and 0.2 to 1 μm.
m is more preferable. If the thickness is less than the lower limit of this range, the glass substrate 5 may not be sufficiently protected. If the thickness exceeds the upper limit, the mask layer 6 may be easily peeled off due to internal stress of the mask layer 6.

The mask layer 6 can be suitably formed by, for example, a chemical vapor deposition method (CVD method). This is because according to the chemical vapor deposition method, a film can be formed by performing a chemical reaction near the surface of the glass substrate 5, so that the occurrence of defects such as pinholes can be effectively suppressed. In addition, it is possible to form a dense and adherent film.

The back surface protective layer 69 is for protecting the back surface of the glass substrate 5 in the subsequent steps. The back surface protective layer 69 suitably prevents erosion and deterioration of the back surface of the glass substrate 5. The back surface protective layer 69 is made of, for example, the same material as the mask layer 6. For this reason, the back surface protective layer 69 is formed simultaneously with the formation of the mask layer 6.
Can be provided in the same manner as described above.

<2> Next, as shown in FIG. 1B, a plurality of openings 61 are formed in the mask layer 6.

The opening 61 is provided at a position where a concave portion is formed. The shape of the opening 61 corresponds to the shape of the recess to be formed.

The opening 61 can be formed, for example, as follows. First, a resist layer (not shown) having a pattern corresponding to the opening 61 is formed on the mask layer 6. Next, using the resist layer as a mask, a part of the mask layer 6 is removed. Next, the resist layer is removed.

The partial removal of the mask layer 6 can be performed, for example, by, for example,
It can be performed by dry etching with CF gas, chlorine-based gas or the like, immersion (wet etching) in a stripping solution such as an aqueous solution of hydrofluoric acid and nitric acid, or an aqueous alkali solution.

<3> Next, wet etching is performed using the etching solution of the present invention to form a large number of recesses 3 on the glass substrate 5 as shown in FIG.

At this time, the glass substrate 5 is isotropically etched through the opening 61. Moreover, the etching solution of the present invention has the above-described effects. Therefore, the concave portion 3 having a very smooth surface and close to an ideal lens shape is formed in the portion where the opening 61 is provided.

The preferable temperature condition for performing wet etching, that is, the preferable temperature range for using the etching solution of the present invention is usually about 5 to 60 ° C., and more preferably about 25 to 50 ° C. Is done. When the etching solution of the present invention is used within this temperature range, a glass substrate can be very suitably etched.

In the wet etching, for example, the glass substrate 5 is immersed in the etching solution of the present invention, the glass substrate 5 is sprayed with the etching solution of the present invention, and the like. Can be carried out by contacting

When the etching solution is brought into contact with the glass substrate 5, that is, the etching time is preferably about 10 minutes to 12 hours, and more preferably about 1 to 4 hours when the concave portion 3 is used for forming a microlens. preferable. Thereby, the concave portion 3 closer to the ideal lens shape can be formed.

<4> Next, as shown in FIG. 1D, the mask layer 6 is removed. At this time, the back surface protective layer 69 is also removed together with the removal of the mask layer 6.

This can be performed, for example, by immersion in a stripping solution such as a hydrofluoric acid + nitric acid aqueous solution or an alkaline aqueous solution (wet etching), dry etching with a CF gas, a chlorine-based gas, or the like.

As a result, as shown in FIG. 1D, a glass substrate with concave portions (substrate with concave portions for microlenses) 2 having a large number of concave portions 3 formed on the surface of a glass substrate 5 is obtained.

By filling the concave portion 3 of the glass substrate 2 with concave portions obtained in this manner with a material having a predetermined refractive index, particularly a material having a higher refractive index than the glass substrate 5 (for example, resin (adhesive)), The micro lens 4 can be formed.

For example, an uncured resin (adhesive) 9 having a higher refractive index than that of the glass substrate 5 is provided on the entire surface of the glass substrate 5 where the concave portions 3 are formed. ) 8 and then curing (solidifying) the resin 9, as shown in FIG.
The microlens substrate 1 can be obtained.

After the glass layer 8 has been joined, the thickness of the glass layer 8 may be adjusted by grinding, polishing or the like as necessary.

The microlens substrate 1 manufactured in this manner is provided with a resin (resin layer) 9 on the surface of the glass substrate 5 having the concave portions 3 in which the concave portions 3 are provided. The glass layer 8 is bonded to the micro lens 4 via the resin 9. The micro lens 4 is formed of the resin 9 by the resin filled in the recess 3.

As described above, the case where a glass substrate with concave portions is manufactured has been described as an example of the method of using the etching solution of the present invention. However, it is needless to say that the etching solution of the present invention can be used for other purposes. . For example, the etching solution of the present invention can be used for forming grooves in glass, adjusting the thickness of glass, and the like.

[0068]

EXAMPLES Hereinafter, "%" means% by weight unless otherwise specified.

1. Production of glass substrate with concave portions and microlens substrate [1.1] Production of glass substrate with concave portions and microlens substrate [1.1.1] First, as an etching solution of the present invention, water, hydrofluoric acid 10% as a solvent, An etching solution (pH 1) having a composition of glycerin 10% was prepared.

Next, using such an etching solution, a glass substrate with concave portions and a microlens substrate were manufactured as follows.

First, an unprocessed quartz glass substrate having a uniform thickness and having no bending or scratches was prepared as a base material. next,
This quartz glass substrate is washed at 85 ° C. with a cleaning solution (80% sulfuric acid + 2
(0% hydrogen peroxide solution) to clean the surface.

-1- Next, a 0.6 μm-thick polycrystalline silicon film was formed on the front and back surfaces of the quartz glass substrate by the CVD method.

This is because a quartz glass substrate is heated at 600 ° C. for 8 hours.
Placed in CVD furnace set to 0 Pa, a SiH ₄ 300
Performed by feeding at a rate of mL / min.

-2- Next, a plurality of openings corresponding to the concave portions to be formed were formed in the formed polycrystalline silicon film.

This was performed as follows. First,
A resist layer having a pattern of a concave portion to be formed was formed on the polycrystalline silicon film using a photoresist. Next, the polycrystalline silicon film was dry-etched with CF gas to form an opening. Next, the resist layer was removed.

-3- Next, the quartz glass substrate was immersed in the prepared etching solution for 2 hours and wet-etched to form a large number of concave portions (with a radius of curvature of 1) on the quartz glass substrate.
0 μm).

The wet etching was performed at a temperature of 30 ° C. An etching rate of about 5 μm / h was obtained.

-4- Next, the quartz glass substrate is immersed in an aqueous solution of tetramethylammonium hydroxide (stripping solution).
The polycrystalline silicon films formed on the front and back surfaces were removed. As a result, a glass substrate with concave portions was obtained.

-5 Next, an ultraviolet (UV) curable epoxy-based optical adhesive (refractive index: 1.60) is applied to the surface of the glass substrate with concave portions where the concave portions are formed, without bubbles. A cover glass made of quartz glass was bonded to the optical adhesive, and then the optical adhesive was irradiated with ultraviolet rays to cure the optical adhesive. Finally, the cover glass was ground and polished to obtain a microlens substrate.

[1.1.2] First, as an etching solution of the present invention, an etching solution (pH 1) having a composition of water, 10% hydrofluoric acid and 10% ethylene glycol was prepared as a solvent.

Next, using the etching solution, a glass substrate with concave portions and a microlens substrate were manufactured in the same manner as described above.

The etching rate in the above section -3- was about 5 μm / h.

[1.1.3] First, as an etching solution of the present invention, an etching solution (pH 1) having a composition of water, 10% hydrofluoric acid, and 10% isopropyl alcohol as a solvent was prepared.

Next, using the etching solution, a glass substrate with concave portions and a microlens substrate were manufactured in the same manner as described above.

The etching rate in the above-mentioned -3- was about 5 μm / h.

[1.1.4] First, as an etching solution of the present invention, water, hydrofluoric acid 10%, glycerin 1
An etching solution (pH 1) having a composition of 0% was prepared.

Next, the polycrystalline silicon film in [1-1] of [1.1.1] is a silicon nitride film, and
A glass substrate with concave portions and a microlens substrate were produced in the same manner as in [1.1.1] above, except that the phosphoric acid solution was changed to a phosphoric acid aqueous solution. Note that the silicon nitride film was formed by a low-pressure CVD method.

The etching rate in the above-mentioned -3- was about 5 μm / h.

[1.2] Evaluation It was confirmed whether or not bubbles were removed in the above-mentioned step-3. In addition, [1.
With respect to each of the glass substrates with concave portions manufactured in [1.1] to [1.1.4], the formed concave portions were evaluated. Further, each manufactured microlens substrate was evaluated.

[1.2.1] The quartz glass substrate and the etching solution immersed in the etching solution were visually observed during the above-mentioned step-3 as appropriate.

As a result, [1.1.1] to [1.
1.4], it was confirmed that bubbles did not adhere to the surface of the quartz glass substrate and smoothly separated from the surface of the quartz glass substrate.

[1.2.2] After completion of the above-mentioned Step-4,
The surface of the glass substrate with each recess was observed with a scanning electron microscope (“S-4500” manufactured by Hitachi, Ltd.).

As a result, a clean hemispherical concave portion was formed in each of the glass substrates with concave portions, and the surface of the concave portion was very smooth, and no irregularities were observed.

[1.2.3] Light was incident on each of the manufactured microlens substrates from the side of the glass substrate having the concave portions, and the light was transmitted. It was confirmed that bright light was emitted from the portion where the was formed.

Further, for each microlens substrate,
A light-shielding film (Cr film) having an opening at a position corresponding to the microlens of the cover glass, that is, a black matrix was formed. Then, with respect to each of the microlens substrates with the black matrix, light was incident from the glass substrate side with the concave portion, and the light was transmitted.

As a result, the light transmittance in the microlens formation region of the microlens substrate with the black matrix was 87% in the above [1.1.1], 85% in the above [1.1.2], and 85% in the above [1.1.2]. 8 in [1.1.3]
5% and 84% in the above [1.1.4].

2. Relationship between concentration of bubble releasing agent, etching rate and smoothness of etched surface The relationship between the concentration of the bubble removing agent and the etching rate was examined as follows. Further, the smoothness of the etched surface of the manufactured glass substrate with concave portions was also examined.

The glycerin concentrations were adjusted to 2, 5,
Etching solutions adjusted to 10, 15, 20, 30, 40, and 50% were prepared. As a comparative example, an etching solution having a glycerin concentration of 0%, that is, a simple hydrofluoric acid aqueous solution was prepared. In these etching solutions, the solvent was water and the concentration of hydrofluoric acid was unified to 10%. The pH of these etching solutions was almost 1.

Next, using these etching solutions, glass substrates with recesses were manufactured in the same manner as in [1.1.1].

At this time, in the course of the above-mentioned Step-3,
The quartz glass substrate and the etchant immersed in the etchant were visually observed. The results are shown in Table 1 below. In the table, it is confirmed that the bubbles were smoothly separated from the quartz glass substrate surface without bubbles adhering to the quartz glass substrate surface, and that the bubbles were smoothly removed from the quartz glass substrate surface. Those that were not detached were marked "x".

[0101]

[Table 1]

FIG. 2 shows the correlation between the glycerin concentration and the etching rate. Here, the etching rate is an etching rate when the above-mentioned step -3- is performed.

The surface of each of the obtained glass substrates with concave portions was observed using a scanning electron microscope in the same manner as in [1.2.2]. The results are also shown in Table 1 above. In Table 1, a beautiful hemispherical concave portion was formed on the quartz glass substrate, the surface of the concave portion was very smooth, and no particular irregularities were observed. When the surface was not smooth and an uneven pattern was observed, it was rated "x".

FIG. 3 shows a scanning electron micrograph of the surface of the glass substrate with the concave portions formed with the etching solution having a glycerin concentration of 15%, on which the concave portions are formed. In addition, also in the glass substrate with a concave portion manufactured using an etching solution having another glycerin concentration, the surface of the concave portion was very smooth as in the case of the photograph. The magnification is 30,000 times.

Further, FIG. 4 shows a scanning electron micrograph of the surface of the glass substrate with concave portions formed with an etching solution having a glycerin concentration of 0%, in which the concave portions are formed. The magnification is 40,000 times.

As can be seen from Table 1 and FIGS.
The etching solution of the present invention has a concentration of the bubble release agent of 2 to 50.
%, It can be said that bubbles can be removed more efficiently while maintaining a high etching rate, and the etched surface can be made smoother. Also,
It can be said that a higher etching rate and the like can be obtained when the concentration of the bubble release agent is 5 to 30%.

Further, the same experiment as described above was conducted by replacing the bubble releasing agent with ethylene glycol and further with isopropyl alcohol. The pH of each of these etching solutions was almost 1.

Table 1 and FIG. 2 also show these results. In addition, when the surface of each of the obtained glass substrates with concave portions was observed with a scanning electron microscope in the same manner as described above, the surface of the concave portions was very smooth, as in the photograph shown in FIG.

[0109]

As described above, according to the present invention, it is possible to provide an etching solution for glass which can make an etching surface smooth.

Further, according to the present invention, it is possible to provide an etching method capable of suitably etching a glass substrate.

Further, according to the present invention, it is possible to provide a glass substrate with a concave portion which is close to an ideal lens shape and has a very smooth lens curved surface, and a microlens substrate.

[Brief description of the drawings]

FIG. 1 is a view for explaining a method for manufacturing a glass substrate with concave portions and a microlens substrate using the glass etching solution of the present invention.

FIG. 2 is a graph showing the correlation between the concentration of a bubble release agent and the etching rate of a glass substrate.

FIG. 3 is a scanning electron microscope (SEM) photograph.

FIG. 4 is a scanning electron microscope (SEM) photograph.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 microlens substrate 2 glass substrate with concave portion 3 concave portion 4 microlens 5 glass substrate 6 mask layer 61 opening 69 backside protective layer 8 glass layer 9 resin

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Hideto Yamashita 3-5-5 Yamato, Suwa-shi, Nagano Seiko Epson Corporation F-term (reference) 4F213 AC05 AD04 AD08 AD24 AF01 AH74 AJ06 AJ08 WA02 WA52 WA85 WB01 WC02 4G059 AA01 AC01 BB04 BB16 BB17 5F043 AA37 BB25 BB28 DD07 DD10 DD30 GG10

Claims (12)

[Claims] 1. A glass etching solution for etching glass, comprising hydrofluoric acid, water, and a bubble release agent for promoting release of bubbles generated on the glass surface. Etchant. 2. The etching solution for glass according to claim 1, wherein the bubble releasing agent is a water-soluble substance having an alcoholic hydroxyl group. 3. The glass etching solution according to claim 2, wherein the bubble releasing agent is a polyhydric alcohol. 4. The glass etching solution according to claim 2, wherein the bubble release agent contains at least one of glycerin, ethylene glycol and isopropyl alcohol. 5. The method of claim 2, wherein the concentration of the bubble release agent is 2 to 50% by weight.
The glass etchant according to any one of claims 1 to 4, wherein 6. The glass etching solution according to claim 1, wherein the concentration of the hydrofluoric acid is 1 to 40% by weight. 7. When the concentration of the hydrofluoric acid is C ₁ and the concentration of the bubble releasing agent is C ₂ , C ₁ : C ₂ is 100: 5.
The etching solution for glass according to any one of claims 1 to 6, wherein the ratio is 100 to 2000. 8. The glass etching solution according to claim 1, which has a pH of 5 or less. 9. An etching method characterized by performing etching by bringing the glass etching solution according to claim 1 into contact with a glass substrate. 10. The etching method according to claim 9, wherein a mask layer made of silicon or silicon nitride is formed on the glass substrate, and the glass etchant is brought into contact with the glass substrate. 11. The etching method according to claim 9, wherein the etching is performed under a temperature condition of 5 to 60 ° C. 12. A micro-electrode comprising a plurality of recesses formed in a glass substrate by the etching method according to claim 9, and the recesses are filled with a material having a higher refractive index than the glass substrate. A method for manufacturing a lens substrate.