JP2001247339A - Method for producing microlens array and method for producing electrooptical apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a new production method capable of readily separating a matrix substrate in a method for producing a microlens array having a step joining two sheets of transparent substrates through a transparent material and making at least either one transparent substrate thin. SOLUTION: Slit holes 11b which extend in a direction which is perpendicular to paper face of the figure are formed by a photolithographic method on the reverse side of a glass substrate 10 as shown in the figure (b). These slit holes 11b are formed along the line separating in a post step. Then, recessed parts 10a composed of a nearly hemispherical concave surfaces are formed on the surface of the glass substrate 10 by subjecting the glass substrate 10 to wet edging as shown in the step (c) and recessed gloves 10b corresponding to the slit holes 11b on the rear surface of the glass substrate 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a microlens array and a method for manufacturing an electro-optical device. More particularly, the present invention relates to a method for forming a plurality of optical surfaces on a surface of one transparent substrate. The present invention relates to a technique for manufacturing a microlens array bonded to another transparent substrate via a material.

[0002]

2. Description of the Related Art Generally, as a method of manufacturing a microlens array, a convex or concave optical surface is formed on the surface of a glass substrate, and another glass substrate is placed on this glass substrate via a transparent resin. There is a method of bonding. In this method, since the refractive index of the transparent resin is different from that of glass, light is refracted by the optical surface, and a predetermined lens characteristic can be obtained.

For example, by providing a microlens array on a liquid crystal panel having pixels arranged in a matrix, which is an example of an electro-optical device, light is condensed in each pixel of the liquid crystal panel, and a liquid crystal panel is formed. There is known a method capable of obtaining the same effect as in the case where the aperture ratio is increased, and the liquid crystal panel configured in this manner is used for light modulation of a liquid crystal projector that requires image brightness. ing. In this case, in order to reduce the thickness of the liquid crystal panel, one glass substrate of the microlens array formed as described above is mechanically ground and polished to reduce the thickness of the microlens array itself. A liquid crystal panel is formed by forming a light-shielding layer, a transparent electrode, and the like, which are arranged between the pixels, and bonding the other to the other glass substrate, and injecting a liquid crystal therebetween.

[0004]

When each of the above-described steps is processed using a plurality of microlens forming portions or a large mother substrate including components for manufacturing a plurality of liquid crystal panels, the processing is performed. It is necessary to separate the subsequent mother substrates from each other. For example, one of the two panel substrates constituting the liquid crystal panel is separated for each liquid crystal panel, or the mother substrates are bonded together to form a liquid crystal panel, and then the liquid crystal panels are separated. I do. Such a separation operation of the mother substrate is generally performed by a method in which a scar is formed on the outer surface of a glass substrate by a diamond cutter or the like, and a stress is applied to the vicinity of the scar to break the formed portion of the scar. However, in the above-described conventional manufacturing method, since the transparent resin is interposed between the two glass substrates, it is difficult to break the glass substrate by the above-described method, and thus the glass substrate is separated by dicing. However, there is a problem that chipping easily occurs by performing dicing, and the yield of products is reduced.

Further, one of the glass substrates constituting the microlens array is ground or polished to make it thinner. However, in this grinding or polishing, it is difficult to process a plurality of microlens arrays at once at a high speed. Therefore, there is a problem that it is not suitable for mass production.

Further, when the thickness is reduced by mechanical grinding or polishing, there is a high possibility that a mechanically damaged layer is formed on the surface of the glass substrate, or the glass substrate is bent or distorted. In some cases, the inner surface structure (light-shielding layer, electrodes, wiring, etc.) of the liquid crystal panel may be affected, and the quality of the liquid crystal panel may be degraded.

Further, when the glass substrate is made extremely thin, the substrate is liable to be cracked or chipped, so that the thickness of the glass substrate is limited, and it is difficult to make the microlens array and the liquid crystal panel sufficiently thin. There is also a problem that it causes a reduction in product yield.

Accordingly, the present invention has been made to solve the above problems, and has as its object to provide a microlens array having a step of joining two transparent substrates via a transparent material and thinning at least one of the transparent substrates. Another object of the present invention is to propose a new manufacturing method which can easily separate a mother substrate. Further, in such a manufacturing method, furthermore, one of the transparent substrates to be thinned is mechanically damaged,
An object of the present invention is to provide a manufacturing method capable of efficiently manufacturing without generating distortion, crack, chipping, and the like.

[0009]

According to the present invention, there is provided a method of manufacturing a microlens array, comprising: forming an optical surface on one of a first transparent substrate and a second transparent substrate; A method for manufacturing a microlens array comprising joining the other of the first transparent substrate and the second transparent substrate with a transparent material having a different refractive index from the material constituting the optical surface via the optical surface Wherein a plurality of pinholes are arranged and formed on a front surface and a back surface of the first transparent substrate at a portion on the surface of the first transparent substrate,
A portion on the back surface of the first transparent substrate is covered with a mask layer having an elongated slit hole, and the first transparent substrate is isotropically etched from the pinhole to form the concave curved optical surface. And performing an etching process for etching the first transparent substrate from the slit hole to form a concave groove. Thereafter, a portion of the mask layer on the surface of the first transparent substrate is removed. later,
The second transparent substrate is bonded to the optical surface via the transparent material.

According to the present invention, a concave curved optical surface is formed on the surface of the first transparent substrate by etching, and a concave groove is formed on the back surface of the first transparent substrate from the slit hole. Since the portion of the transparent substrate where the groove is formed can be formed thin, it can be broken along the portion where the groove is formed, and the structures of the microlens array can be separated from each other. Therefore, there is no need to perform dicing as in the related art, and the occurrence of chipping or the like can be prevented, or dicing can be performed more easily, so that the product yield can be improved. Further, since it is not necessary to provide a step for forming the concave groove, it is possible to suppress an increase in manufacturing cost. Furthermore, since the slit hole is formed before forming the optical surface,
The dust and the like generated from the mask layer remaining on the optical surface after the formation of the optical surface are not affected by the patterning of the slit holes.

In the present invention, it is preferable that after the first transparent substrate and the second transparent substrate are bonded on the optical surface via the transparent material, the thickness of the second transparent substrate is reduced by etching. .

According to the present invention, the second transparent substrate is thinned by the etching process, thereby causing mechanical damage to the second transparent substrate, bending or distortion of the glass substrate, cracking of the substrate, or the like. Since the second transparent substrate can be made thinner than before without causing any chipping or chipping, the microlens array can be made thinner without lowering the yield.

Next, as a method of manufacturing a microlens array according to the present invention, an optical surface is formed on one surface of a first transparent substrate and a second transparent substrate, and the material constituting the optical surface is as follows. A method of manufacturing a microlens array comprising joining the other of the first transparent substrate and the second transparent substrate with transparent materials having different refractive indices on the optical surface, the method comprising: After joining the first transparent substrate and the second transparent substrate through the transparent material, the outer surface of the first transparent substrate is covered with a mask layer having etching resistance and having an elongated slit hole. An etching process is performed in a state where the second transparent substrate is covered with the mask layer, and a groove is formed on an outer surface of the first transparent substrate.

According to the present invention, the second transparent substrate is thinned by etching and a groove is formed on the back surface of the first transparent substrate from the slit hole, so that the portion of the first transparent substrate where the groove is formed is formed. Since it can be formed thin, it can be broken along the portion where the concave groove is formed, and the structures of the microlens array can be separated from each other.
Therefore, there is no need to perform dicing as in the related art, and the occurrence of chipping or the like can be prevented, or dicing can be performed more easily, so that the product yield can be improved. In particular, since the groove can be formed deeply by forming the groove at the same time as the thickness of the second transparent substrate is reduced, the separation operation by breaking the first transparent substrate can be easily performed. Further, since it is not necessary to provide a step for forming the concave groove, it is possible to suppress an increase in manufacturing cost. Further, by reducing the thickness of the second transparent substrate by etching,
Since the second transparent substrate can be made thinner than before without causing mechanical damage to the transparent substrate, bending or distortion of the glass substrate, or causing cracking or chipping of the substrate. In addition, it is possible to reduce the thickness of the microlens array without deteriorating the yield.

Here, the surface of the first transparent substrate is covered with a mask layer, a plurality of pinholes are formed in the mask layer, and the first transparent substrate is isotropically etched from the pinholes. In some cases, the concave curved optical surface is formed, the mask layer is removed, and then the second transparent substrate is bonded to the optical surface via the transparent material. In this case, after forming a mask layer on the front and back of the first transparent substrate and forming the optical surface by etching, only the portion of the mask layer on the surface of the first transparent substrate may be removed. Further, in the removing step, the first
The slit holes may be simultaneously formed in the mask layer on the back surface of the transparent substrate.

In the present invention, it is preferable to form a small groove by making the etching time for forming the groove on the outer surface of the first substrate shorter than the etching time for thinning the second substrate.

Further, in the present invention, by coating the outer surface of the first transparent substrate with a mask layer having etching resistance, only the second transparent substrate can be thinned even if the entire microlens array is etched. Therefore, the etching process is facilitated, and a large number of microlens arrays can be processed at once, so that productivity can be improved and mass production can be easily performed. Here, the outer surface of the first transparent substrate refers to a surface that is exposed to the outside, such as a plate surface or a side surface of the first transparent substrate opposite to the plate surface facing the second transparent substrate. However, it is not always necessary to form a mask layer on the side surface of the first transparent substrate. here,
Having etching resistance means having an etching rate as small as not to lose the mask cover by the above-mentioned etching treatment, and means having an etching rate smaller than at least the second transparent substrate.

In the present invention, the first transparent substrate is preferably a glass substrate, and the etching is preferably performed by wet etching using a mixed solution of hydrofluoric acid and ammonium fluoride. Further, in the present invention, the first
The transparent substrate and the second transparent substrate are glass substrates, and the etching treatment is preferably performed by wet etching using a mixed solution of hydrofluoric acid and ammonium fluoride.

According to these inventions, the glass substrate is subjected to wet etching using a mixed solution of hydrofluoric acid and ammonium fluoride, so that only hydrofluoric acid is used as a main component, Since the etching rate with respect to the glass substrate can be extremely increased as compared with the case where a mixed solution with the components is used, the second transparent substrate can be thinned quickly.

In the present invention, the mixed solution is preferably prepared and used so that the weight ratio of hydrofluoric acid to ammonium fluoride is in the range of about 0.2 to 6.

According to the present invention, by adjusting and using the weight ratio of hydrofluoric acid and ammonium fluoride to be in the range of about 0.2 to 6, it is possible to maintain a high etching rate for the glass substrate while maintaining a high etching rate. Since the ratio of the etching rate between the glass substrate and the other material having etching resistance can be kept high, the etching process can be easily performed. In particular, in the case where the etching treatment is performed after forming the mask layer, it is not necessary to form the mask layer thick, so that the formation of the mask layer becomes easy. In this case, in particular, in the case where polycrystalline silicon, silicon nitride, silicon carbide, or the like is used as the mask layer, it is not necessary to form the mask layer thick, so that separation of the mask layer due to an increase in internal stress is prevented. Can be.

The above-mentioned hydrofluoric acid means an aqueous solution of hydrogen fluoride having a concentration of 50%.

In the present invention, it is preferable that the mask layer is formed of a polycrystalline silicon film, a silicon nitride film or a silicon carbide film.

According to the present invention, the polycrystalline silicon film, the silicon nitride film, or the silicon carbide film generally has etching resistance to the etching treatment of glass or the like, so that the etching treatment is facilitated and the etching treatment becomes easy. It can be easily formed by a phase growth method or the like.

In the present invention, the mask layer is formed by a low-pressure CV
It is preferably formed by the method D.

According to the present invention, a polycrystalline silicon film,
Since the silicon nitride film or the silicon carbide film can be formed with a dense film quality, permeation of an etching solution at the time of etching treatment can be prevented.

In the present invention, the optical surface may be formed by molding using a transparent material having a refractive index different from that of the transparent material.

In the present invention, the etching process is performed in a state where the outer surface of the first transparent substrate is covered with a mask layer having etching resistance, and the mask layer is made of an amorphous silicon film, Pt or Au, or a film made of these materials. It is preferable that the metal film is made of an alloy containing a metal. In this case, a low-temperature film formation method such as a sputtering method can be used by using an amorphous silicon film or a metal film made of Pt or Au or an alloy containing these as the mask layer. In the case of the described method, a film can be formed without any trouble even if a resin having relatively low heat resistance is used as the transparent material.

In the present invention, the resist material arranged on the first transparent substrate is softened to form a convex curved surface, and an etching process is performed on the surface to form a convex curved surface of the resist material. The corresponding convexly curved optical surface may be formed on the first transparent substrate.

According to a method of manufacturing an electro-optical device of the present invention, a micro-lens array is formed by the above-described method of manufacturing a micro-lens array, and further, electrodes are formed on the inner surface of the second transparent substrate of the micro-lens array. A separate substrate provided with the other electrode opposed to the electrode is attached to the substrate.

According to the present invention, since the second transparent substrate is thinned by the etching process, there is little mechanical damage on the surface of the second transparent substrate. The quality of a body (for example, liquid crystal) can be improved, and a high-quality electro-optical device can be configured.

In the present invention, it is preferable that a light-shielding layer is formed on the surface of the second transparent substrate in a region corresponding to the interval between the optical surfaces.

According to the present invention, by providing the light-shielding layer, only the light condensed by the microlens array can be introduced into the center of the pixel and emitted after the light is modulated. It is possible to achieve both strength and quality. In particular, when a projection display device using an electro-optical device is formed, it is particularly preferable because brightness of an image can be compatible with image quality.

[0034]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of a method for manufacturing a microlens array according to the present invention will be described in detail with reference to the accompanying drawings. Each of the embodiments described below relates to a microlens array used as a part of a liquid crystal panel. However, the present invention is not limited to a liquid crystal panel, and in particular, various electro-optical devices, for example, EL (electroluminescence). It is preferably used for a panel having various electro-optical panels such as a panel and an organic EL panel. Further, the present invention is not limited to those used for the above-mentioned electro-optical device, and is used for manufacturing microlens arrays widely used for various purposes. It is possible to apply.

[First Embodiment] FIGS. 1 and 2 are process explanations showing a method of manufacturing a microlens array for a liquid crystal panel and a part of a method of manufacturing a liquid crystal panel according to a first embodiment of the present invention. FIG.

In this embodiment, first, as shown in FIG.
A mask layer 11 made of a polycrystalline silicon film is formed by a VD (chemical vapor deposition) method. As the mask layer 11,
In addition to a polycrystalline silicon film, a silicon nitride film, a silicon carbide film, or the like can be formed. Preferably, the thickness of the mask layer 11 is about 1 μm. Low-pressure CVD for producing a polycrystalline silicon film includes, for example, silane, hydrogen,
Nitrogen and other inert gases are stored in the glass substrate,
It is carried out by supplying into a chamber heated to about 500 to 600 degrees. In this step, in order to form the mask layer 11 on almost all the outer surfaces of the glass substrate 10, for example, a plurality of glass substrates 10 are arranged so as to stand on a carrier and a film is formed.

Next, as shown in FIG. 1B, a plurality of pinholes 11a are formed in the mask layer 11 on one surface (the upper surface in the figure) of the glass substrate 10. The plurality of pinholes 11a are formed on the mask layer 11 by a patterning technique such as a photolithography method or a perforation technique using laser beam irradiation. Pinhole 11
a is arranged in accordance with the arrangement of the optical center of each microlens in the microlens array to be manufactured. The opening diameter of the pinhole 11a is desirably sufficiently smaller than the diameter of a concave portion 10a to be actually formed, which will be described later, and is, for example, about 5 μm. At this time,
A slit hole 11b extending in a direction perpendicular to the plane of the drawing is formed on the back surface (the lower surface in the figure) of the glass substrate 10 by a photolithography method or the like. This slit hole 11b is formed along a line that separates the glass substrate 10 in a later step, and the slit hole 11b shown in the illustrated example has a shape extending in a direction perpendicular to the plane of the drawing. . The slit hole 11b can be formed based on the alignment mark for forming the pinhole 11a or the pinhole 11a itself formed according to the mark. The slit holes 11b are formed, for example, in a lattice shape along a boundary separating the glass substrate 10. At the time when this etching process has not been performed yet, the slit holes 11
By forming b, it is possible to prevent a patterning failure or the like due to dust generated from the mask layer 11 in a state shown in FIG. 1C described later, so that the slit hole 11b can be formed easily and with high precision.

Next, as shown in FIG. 1C, a concave portion 10a having a substantially hemispherical concave curved surface is formed on the surface of the glass substrate 10 by performing wet etching on the glass substrate 10. A concave groove 10b corresponding to the slit hole 11b is formed on the back surface of the substrate 10. For this wet etching, an etchant capable of isotropically etching the glass substrate 10, for example, a hydrofluoric acid-based etchant such as a mixed aqueous solution of hydrogen fluoride and nitric acid is used. The surface of the recess 10a becomes the optical surface of the microlens. However, this step is not limited to wet etching, and may be performed by various dry etching using carbon tetrafluoride, oxygen, chlorine, or the like as an active species.

In the present embodiment, a substantially hemispherical concave portion 10a having a circular contour in a plan view is formed on the surface of the glass substrate 10.
However, depending on the shape of the pinhole 11a, the contour shape is not limited to a circle, but may be formed into various shapes such as a rectangle and a square. The diameter of the concave portion 10a varies depending on the purpose of use and the field of use of the microlens array, for example, 1 to 100 μm, preferably 10 to 5 μm.
It is about 0 μm. Electro-optical devices, particularly those used for liquid crystal devices, are formed to have substantially the same size as each pixel region.

In the present embodiment, the thickness of the glass substrate 10 in the portion where the concave groove 10b is formed can be extremely reduced at the same time when the concave portion 10a is formed. The thickness of this portion is determined in consideration of the easiness of rupture at the time of rupture operation described later and the ease of handling in each step until the rupture operation. The thickness is preferably about 100 to 900 μm, and more preferably about 200 to 500 μm, in order to easily break at the time of the breaking operation and to prevent the groove portion from being broken by mistake before that.

Next, as shown in FIG.
mask layer 11 on the front side of glass substrate 10 on which a is formed
Is removed. At this time, the mask layer 11 formed on the side surface and the back surface of the glass substrate 10 is left without being removed. Such selective removal is carried out by protecting the coating with a rubber negative resist. The removal of the mask layer 11 made of a polycrystalline silicon film is performed using an aqueous alkaline solution such as aqueous ammonia or aqueous potassium hydroxide. In the case of a silicon nitride film or a silicon carbide film, it can be removed with phosphoric acid or the like. The silicon carbide film can be removed by dry etching using CF and oxygen gas. Since all of these etchants have a lower etching rate with respect to the glass than the mask layer 11, the mask layer 11 can be removed without substantially affecting the shape of the concave portion 10a.

Next, as shown in FIG. 2A, a glass substrate 14 is bonded to the side of the glass substrate 10 on which the concave portion 10a is formed via a transparent resin 13 having an adhesive function. As the transparent resin 13, for example, a transparent thermosetting or light-curing resin (adhesive) such as an epoxy resin can be used. In this bonding step, the concave portion 10a of the glass
A transparent resin 13 is applied on the top, and a glass substrate 14
And pressurize. Then, after positioning the glass substrate 14 so that the transparent resin 13 has a predetermined thickness,
For example, in the case of an ultraviolet curable resin, the transparent resin 13 is cured by irradiating ultraviolet rays. When used to form a part of a liquid crystal panel as described later, the transparent resin 13 is made of a material having a higher refractive index than the glass substrate 14.

Next, as shown in FIG. 2B, the glass substrate 14 is thinned by etching. Glass substrate 1
As 0 and 14, those having a thickness of about 0.7 to 1.2 mm are generally used from the viewpoint of handleability and material cost, but when two glass substrates having such a thickness are bonded together, the overall The result is a very thick microlens. In the present embodiment, the glass substrate 14 is immersed in an etchant to etch the outer surface (the upper surface in the drawing) and the concave groove 10 b of the glass substrate 14 which are not covered by the mask layer 11, thereby reducing the thickness of the glass substrate 14.

In the case of the present embodiment, a mixed aqueous solution of hydrogen fluoride and ammonium fluoride is used as the etching solution in the etching process. In this etching _{solution, HF + NH 4 F → NH} 4 + + F - for divergence of the ion represented by (1) occurs at a rate nearly ^{100%, HF + F - →} HF 2 - (2) HF _2, which is formed by the formula ^- ions contributing to etching occurs in large quantities. The HF ₂ ^- is the ion concentration directly affects the etch rate. That is, silicon oxide (glass) is rapidly removed (2H ₂ O → H ₃ O ⁺ ) by the following formula: SiO ₂ + 2HF ₂ ⁻ + 2H ₃ O ⁺ → SiF ₂ ⁻ + 4H ₂ O (3) + OH ^-). The relationship between the composition ratio and the etching rate in this case is shown in FIG. 9A as described later.

On the other hand, when ammonium fluoride does not exist, that is, when only hydrofluoric acid is used, the degree of ion dissociation of HF ⁻ + H ₂ O → H ₃ O ⁺ + F ⁻ (4) is extremely large. small, as a ^{result, HF - + F - → HF} 2 - (5) HF 2 , which is formed by the formula ^- for ion concentration very small, the etching rate for the glass is low. In this case, FIG. 9B shows the relationship between the concentration of hydrofluoric acid and the etching rate in an etching solution containing 15% by volume of glycerin and the remainder consisting of hydrofluoric acid and water. As described above, when only hydrofluoric acid is used as an etching main component, the etching rate is extremely low, and thus it is understood that the etching liquid is inappropriate as an etchant for the glass substrate 14 used in the present embodiment.

As described above, when ammonium fluoride is added to hydrogen fluoride, the etching rate for the glass substrate 14 is greatly increased. In FIG. 9A, the horizontal axis represents the weight ratio between hydrofluoric acid and ammonium fluoride in the etching solution, and the vertical axis represents the etching rate (μm / hour) with respect to the glass substrate and the etching selectivity between the glass substrate and polycrystalline silicon. A graph taken is shown. In FIG. 9A, the solid line in the figure shows the etching rate, and the broken line in the figure shows the etching selectivity (ratio between the etching rate for glass and the etching rate for polycrystalline silicon). As can be seen from this graph, when ammonium fluoride is added to hydrofluoric acid, the etching rate sharply increases. However, when the ratio of hydrofluoric acid to ammonium fluoride exceeds 1, the etching rate increases as the ratio of ammonium fluoride increases. Decrease. In general, the etching selectivity gradually decreases as the amount of ammonium fluoride increases.

In this embodiment, the glass substrate 14 needs to be largely etched, while the mask layer 11 has a thickness of 1 μm.
Even if the coating layer 12 is left as it is on the mask 11 and etched, the mask layer 11 must be thickened if the etching selectivity becomes low. As described above, the mask layer 11 is formed of polycrystalline silicon, silicon nitride, silicon carbide, or the like. However, when these are deposited thickly, the internal stress increases and the film is easily peeled off. Has a limit. Therefore, considering both the etching rate and the etching selectivity, the volume ratio of hydrofluoric acid to ammonium fluoride is generally about 0.2 to 6, as shown in FIG. More preferably, when importance is placed on the etching selectivity, when the thickness of the mask layer 11 is reduced, the thickness is preferably about 0.3 to 3. In particular, from the viewpoint of increasing the etching rate, the volume ratio is desirably about 0.5 to 1.3. Note that the above-mentioned hydrofluoric acid has a concentration of 50%
Means an aqueous solution of hydrogen fluoride.

In this embodiment, since the glass substrate 14 is thinned by etching as described above, there is almost no possibility that the glass substrate 14 itself is damaged, bent, or distorted due to mechanical stress. However, there is no possibility of damaging the entire microlens. Further, in the present embodiment, since the thickness is reduced by etching, the glass substrate 14 can be formed extremely thin. In the present embodiment, it is possible to reliably reduce the thickness of the glass substrate 14 to about 50 μm without cracking or chipping.

As described above, a microlens array including the glass substrate 10, the transparent resin 13, and the glass substrate 14 is formed. Although the microlens array can be used for various purposes, in the present embodiment, a glass substrate 14 constituting the microlens array is used as one liquid crystal panel substrate to form a liquid crystal panel incorporating the microlens array. are doing. Here, the outer surface of the glass substrate 10 is covered with a mask layer 11, which is removed with an aqueous alkali solution such as aqueous ammonia or aqueous potassium hydroxide.

Next, when a liquid crystal panel to be described later is formed using the microlens array formed as described above, as shown in FIG. A light-shielding layer 15 made of a metal, a black matrix, or another light-shielding material is formed by each lens portion of the microlens array (configured by the concave portion 10a).
Are formed in a grid pattern in the region between the two. Then, a transparent conductor such as ITO (indium tin oxide) is deposited on the light-shielding layer 15 by an evaporation method, a sputtering method, or the like to form the transparent electrode 16.

In this embodiment, since the glass substrate 14 is thinned by etching, for example, a large number of microlens arrays can be processed simultaneously in parallel, so that mass production can be easily performed. In particular, unlike conventional mechanical processing, the glass substrate can be thinned without giving any mechanical damage, bending, distortion, etc., and the yield is improved because there is no danger of cracking or chipping. In addition, it can be processed to an extremely thin state of about several tens of μm.

By forming polycrystalline silicon, silicon nitride, silicon carbide and the like by low-pressure CVD, a dense and pinhole-free mask layer can be formed, so that the optical surface of the microlens can be precisely formed. can do. Further, productivity can be improved because films can be formed on both surfaces of the glass substrate at one time.

Finally, the mother substrate of the microlens array formed as shown in FIG. 2 (d) is broken by applying a stress to a portion indicated by a dotted line A along the concave groove 10b. Are separated from each other. Although it depends on the thickness of the portion where the concave groove 10b is formed, the formation of the concave groove allows the glass substrate 10 to be broken with relatively small stress, and the glass substrate 14 is also thinned in the etching step. Because of this, both can be easily broken. Therefore, in the present embodiment, there is no need to provide a dicing step as in the related art.
Productivity can be improved, occurrence of defects such as chipping can be prevented, and yield can be improved.

[Second Embodiment] Next, a second embodiment according to the present invention will be described in detail with reference to FIGS. In this embodiment, basically the same steps as those in the first embodiment are followed, but only the above-described concave groove forming step for separating the mother substrate is different from that in the first embodiment. The reference numerals are used, and the description is omitted.

In this embodiment, as shown in FIG. 3A, a mask layer 11 is formed on the front and back of a glass substrate 10 in the same manner as in the first embodiment, and as shown in FIG. The same pinholes 11a as described above are arranged and formed on the portion of the layer 11 formed on the surface of the glass substrate 10. Then, as shown in FIG. 3C, a concave portion 10a serving as an optical surface is formed on the surface of the glass substrate 10 by etching. Thereafter, as shown in FIG. 3D, the mask layer 11 on the back surface and the side surface of the glass substrate 10 is coated with a coating layer 12 of a rubber-based negative resist, and tetramethyl hydroxide heated to 50 to 70 ° C. The mask layer 11 on the surface of the glass substrate 10 is removed with an aqueous ammonium solution.

At this time, instead of performing the step of forming the slit holes 11b and 12b described in the step of FIG. 4B described later, the slit is formed simultaneously with the step of removing the portion of the mask layer 11 on the surface of the glass substrate 10. A hole may be formed. That is, after forming a slit hole 12b in the above-mentioned coating layer 12 by using a photolithography process, FIG.
An etching step shown in FIG. 1D is performed, and in this step, slit holes 11b are also formed in the mask layer 11.

Next, as shown in FIG. 4A, the glass substrate 14 is interposed via the transparent resin 13 in the same manner as in the first embodiment.
Glue.

Next, as shown in FIG. 4B, in the mask layer 11 and the coating layer 12 which cover the back surface (the lower surface in the figure) of the glass substrate 10, extended slit holes 11b and 12b are respectively formed at the same positions. It is formed by a lithography method or the like. These slit holes 11b, 12b are formed along a line separating the glass substrate 10 in a later step, and the slit holes 11b, 12b shown in the illustrated example are formed.
Has a shape in which the slit hole extends in a direction perpendicular to the plane of the drawing. These slit holes 11b, 12b
Are formed in a lattice shape on the plate surface of the glass substrate 10, for example. In this state, the thickness of the glass substrate 14 is reduced similarly to the first embodiment. At this time, the slit holes 11b, 1
A groove 10b is also formed on the back surface of the glass substrate 10 through 2b.

In the case of the present embodiment, the glass substrate 14
Since the concave groove 10b is formed in the glass substrate 10 by etching from the slit holes 11b and 12b simultaneously with the etching step, the thickness of the glass substrate 10 in the portion where the concave groove 10b is formed can be extremely reduced. . The thickness of this portion can be set to about 50 μm as described above. Determined by taking into account. In order to make it easy to break at the time of breaking work, and to prevent the groove portion from being broken beforehand by mistake, as the thickness, 100 to 100
It is preferably about 800 μm, and more preferably 100 to 500 μm.
m is desirable.

Thereafter, the coating layer 12 is removed by immersing it in a mixed solution of sulfuric acid and hydrogen peroxide heated at 100 ° C. for 30 minutes. After that, the mask layer 11 on the back surface is
It is immersed in tetramethylammonium hydroxide heated to 0 ° C. for 5 minutes and peeled off.

Thereafter, as shown in FIG. 4C, a light-shielding layer 15 and a transparent electrode 16 were formed on the surface of the glass substrate 14, and a concave groove 10b was formed as shown in FIG. 4D. The microlens array is separated by applying a stress along the illustrated dotted line A and breaking it.

In this embodiment, since the concave groove 10b is formed in the etching step for thinning the glass substrate 14, the concave groove 10b can generally be etched deeply, and the concave groove 10b is formed along the concave groove 10b. The separation operation of the microlens array can be performed more easily.

Third Embodiment A third embodiment according to the present invention will be described in detail with reference to FIGS. In this embodiment, basically, the second
Although steps similar to those of the embodiment are followed, only the step of forming the concave groove for separating the mother substrate described above is different from that of the second embodiment. Corresponding portions are denoted by the same reference numerals and description thereof will be omitted.

In this embodiment, as shown in FIG. 5A, a mask layer 11 is formed on the front and back of a glass substrate 10 in the same manner as in the first embodiment, and as shown in FIG. Pinholes 11a similar to those described above are arranged and formed in a portion formed on the surface of the glass substrate 10 of FIG.

Then, as shown in FIG. 5C, a concave portion 10a serving as an optical surface is formed on the surface of the glass substrate 10 by etching. Thereafter, as shown in FIG. 5D, the mask layer 11 on the back surface and the side surface of the glass substrate 10 is coated with the coating layer 12 using the same negative resist as above, and the mask on the surface of the glass substrate 10 is formed. Layer 11 is removed.

Next, as shown in FIG.
Is bonded via a transparent resin 13 in the same manner as in the first embodiment, and then a slit hole 12b for forming a concave groove 10b is formed in the coating layer 12 using a negative resist by using photolithography.

Thereafter, the glass substrate 14 is etched using a hydrofluoric acid-based etchant. Glass substrate 1 at this time
4 is calculated as [thickness of glass substrate 14 after etching = thickness of glass substrate 10 before etching− (thickness (target value) of glass substrate 10 in concave groove 10b forming portion) + ( Etching is performed up to the thickness calculated by [thickness of glass substrate 14 after thinning (target value)]].

Thereafter, a slit hole 11b of polycrystalline silicon is formed using an aqueous alkali solution such as 10% potassium hydroxide heated to 50 ° C., as shown in FIG. 6 (b).

Further, the glass substrate 14 is etched with a hydrofluoric acid aqueous solution to a predetermined thickness. At this time, the slit hole 11
An etching solution enters b, and a concave groove 10b is formed, as shown in FIG. The most significant feature of the present embodiment is that the thickness of the substrate 10 at the portion where the concave groove 10b is formed can be arbitrarily changed. This is because, by changing the thickness, the optimum thickness can be freely set regardless of the change of the glass substrates 10 and 14.

Then, after the coating layer 12 is stripped with a negative resist stripping solution or a mixed solution of sulfuric acid and hydrogen peroxide solution,
The polycrystalline silicon film 11 is also peeled off using an alkaline aqueous solution. Thereafter, as shown in FIG. 6D, a light shielding layer 15 and a transparent substrate 16 are formed on the surface of the glass substrate 14,
As shown in FIG. 6E, the microlens array is separated by applying a stress along the illustrated dotted line A where the concave groove 10b is formed and breaking it.

In this embodiment, since the concave groove 10b is formed in the etching step for thinning the glass substrate 14, the depth of the concave groove 10b can be freely changed, and the depth which is most excellent in workability can be obtained. Can be set easily. for that reason,
The dicing operation can be performed more easily without the need for dicing.

[Fourth Embodiment] Next, a fourth embodiment of the method for manufacturing a microlens array according to the present invention will be described with reference to FIG.

In this embodiment, as shown in FIG. 7A, first, a lens mold 20 formed by molding a semiconductor material such as various metals or silicon is used, and a glass substrate similar to that of the first embodiment is used. 21 is bonded to the lens mold 20 via a transparent resin 22. The bonding method in this bonding step is almost the same as that described in the first embodiment. The lens mold 20 has concave curved concave portions 20a arranged in a lattice shape. After the transparent resin 22 is cured, the lens mold 20 is peeled off and removed, and the convex curved concave shape corresponding to the concave portion 20a is formed. An optical surface 22a is formed.

Next, as shown in FIG. 7B, a transparent resin 23 is applied to the surface on the optical surface 22a side, and a glass substrate 24 is adhered from above. This bonding process is also described in FIG.
This is performed in the same manner as in the first embodiment, similarly to the method shown in FIG. The transparent resin 23 has a refractive index different from that of the transparent resin 22. When a liquid crystal panel is formed by a method described later, a material having a lower refractive index than the transparent resin 22 is selected.

Next, as shown in FIG. 7C, a mask layer 25 is formed on the side surface and the back surface (the lower surface in the figure) of the glass substrate 21. The mask layer 25 uses amorphous silicon, Pt, or Au as an upper layer instead of polycrystalline silicon, silicon nitride, silicon carbide, or the like described in the first embodiment.
In order to improve adhesion, it is preferable to use a Cr or Ti film as a base layer and form the film by a low-temperature film formation method such as a sputtering method. This is because these materials can be formed into a high-quality film by a low-temperature film forming method, so that the transparent resins 22 and 23 do not require high heat resistance. Here, it is preferable that the mask layer 25 is formed to extend to the side surfaces of the transparent resin 22 and the transparent resin 23, and further, the mask layer 25 is formed to extend to the side surface of the glass substrate 24 near the interface with the transparent resin 23. May be.

After forming the mask layer 25, the mask layer 2
5, a slit hole 25b is formed on the outer surface of the glass substrate 21.
Is formed by a photolithography method or the like. Then, the outer surface (upper surface in the drawing) of the glass substrate 24 is removed by etching, and the thickness is reduced as shown in the drawing. This etching method is exactly the same as in the case of the first embodiment.
At this time, a concave groove 21b is formed on the outer surface of the glass substrate 21 by the slit hole 25b.

Finally, as shown in FIG. 7D, a light-shielding layer 26 and a transparent electrode 27 similar to those of the first embodiment are formed on the surface of the glass substrate 24 thinned by etching. As described in one embodiment, the mask layer 25 is removed at an appropriate timing. Then, the microlens arrays are broken apart from each other along the concave grooves 21b and separated.

In this embodiment, basically the same effects as in the first embodiment can be obtained. However, since the optical surface 22a is formed by using the lens mold 20,
There is an advantage that the shape and arrangement of the optical surface can be formed relatively freely and with high precision.

[Fifth Embodiment] Next, a fifth embodiment of the method for manufacturing a microlens array according to the present invention will be described with reference to FIG.

In this embodiment, as shown in FIG. 8A, a projection 31 is formed on a glass substrate 30 so as to protrude in a convex curved shape shown by a dotted line. The projections 31 are formed by arranging in advance materials having predetermined etching characteristics (such as resist materials and other organic resins) on the surface of the glass substrate 30, and imparting a certain degree of fluidity by heating, for example. Viscosity and glass substrate 3 according to its fluidity
It is formed into a convex curved shape as shown in the figure by wettability to zero. Then, when the surface of the glass substrate 30 is etched together with the protrusions 31 by, for example, a dry etching method, the protrusions 31 are completely disappeared before long, and as shown by a solid line in FIG. The surface of the substrate 30 has a shape in which a large number of convexly curved optical surfaces 30a are arranged.

Next, as shown in FIG. 8B, a transparent resin 3 is formed on the surface of the glass substrate 30 on which the optical surface 30a is formed.
2 and the glass substrate 33 is bonded to the transparent resin 3
2 by curing. This bonding step is performed in the same manner as in the first embodiment. As the transparent resin 32, a material having a different refractive index from that of the glass substrate 30 is selected. When the transparent resin 32 is formed as a part of a liquid crystal panel as described later, a material having a lower refractive index than the glass substrate 30 is selected.

Next, as shown in FIG. 8C, a mask layer 34 is formed on the side surface and the back surface (the lower surface in the figure) of the glass substrate 30. The mask layer 34 is formed of the same material as in the first embodiment and by the same method. The mask layer 34 is desirably formed so as to extend to the side surface of the transparent resin 32. Further, the mask layer 34 may be extended to the side surface of the glass substrate 33 near the interface with the transparent resin 32.
In the mask layer 34, a slit hole 34b is formed on the outer surface of the glass substrate 30 by a photolithography method or the like.

Then, the glass substrate 3 is etched.
Etching the outer surface (upper surface in the figure) of the glass substrate 3
3 is thinned. This etching step is performed in exactly the same manner as in the first embodiment. In this etching step, the concave groove 30b is formed on the outer surface of the glass substrate 30 at the position where the slit hole 34b is formed, as the glass substrate 33 is thinned.

Finally, as shown in FIG. 8D, a light shielding layer 35 and a transparent electrode 36 are sequentially formed on the surface of the glass substrate 33 as in the first embodiment. Further, the mask layer 34 is removed at an appropriate timing. Then, similarly to the above embodiments, the microlens arrays are separated from each other by breaking along the concave grooves 30b.

In this embodiment, the same effects as those of the above embodiments can be obtained.

[0086] Although a glass substrate is used in each of the above embodiments, a quartz substrate may be used instead of the two glass substrates bonded with the optical surface interposed therebetween. In this case, in the first embodiment and the second embodiment, the isotropy of etching is increased when forming the optical surface.
The optical surface of the microlens can be formed in a smooth and accurate shape. Further, in any of the above embodiments, the surface of the substrate whose thickness is reduced by the etching can be formed smoothly with respect to the substrate whose thickness is reduced by the etching.

In the above embodiment, the mask layer is also formed on the side surface of the glass substrate. However, the mask layer may not be formed on the side surface of the glass substrate. This is because the side etching amount is small compared to the area of the glass substrate, and there is no problem if the side etching amount is also considered in advance.

[Structure of Liquid Crystal Panel] Next, the structure of a liquid crystal panel which is an embodiment of a liquid crystal device formed using the above-described microlens will be described. FIG.
The structure of the active matrix type liquid crystal panel formed by breaking the structure formed in the embodiment along the concave groove and using the separated substrate as the counter substrate 40 is shown. In this liquid crystal panel, an element substrate 50 in which an active element 51 such as a TFT (thin film transistor) is formed for each transparent pixel electrode 52 is formed. Then, a liquid crystal panel is formed by bonding the element substrate 50 to the counter substrate 40 via a sealing material (not shown). Liquid crystal 53 is injected between the opposing substrate 40 and the element substrate 50 and sealed. Note that an alignment film (not shown) is formed on the opposing inner surfaces of the opposing substrate 40 and the element substrate 50 that are in contact with the respective liquid crystals 53.

In this liquid crystal panel, the substrates are bonded so that the microlenses formed on the opposing substrate 40 correspond to the transparent pixel electrodes 52 formed on the element substrate 50. As a result, in the liquid crystal panel, the transparent electrode 1
6. A microlens is formed corresponding to each pixel constituted by the transparent pixel electrode 52 and the liquid crystal 53 sandwiched therebetween. Therefore, the light incident from the counter substrate 40 side is condensed by the microlens, introduced into the pixel, and then emitted from the element substrate 50 to the outside. As a result, the aperture ratio of the pixel in the liquid crystal panel is
Even if it is limited by forming a liquid crystal panel, a large amount of light can be intensively transmitted and emitted in the central portion of the pixel, so that the controlled amount of transmitted light of the liquid crystal panel can be increased, and the image quality can be improved. Also improve.

FIG. 11 shows the structure of a liquid crystal panel in which the structure formed according to the third embodiment is broken along the grooves and separated from each other as a counter substrate 60. Also in this liquid crystal panel, an element substrate 70 on which an active element 71 and a transparent pixel electrode 72 are formed as in the liquid crystal panel shown in FIG. 10 is formed. Then, the counter substrate 60
The liquid crystal 73 is injected between the substrate and the element substrate 70 via a sealing material (not shown). The counter substrate 6
An alignment film (not shown) is formed on opposing inner surfaces of the element substrate 70 and the liquid crystal 73 in contact with each other.

In this liquid crystal panel, similarly to the above, light incident from the counter substrate 60 side is condensed by the microlens, and is constituted by the transparent resin 22, the transparent pixel electrode 72, and the liquid crystal 73 sandwiched therebetween. The light is introduced into the pixel and emitted from the element substrate 70.

Next, the overall structure of a panel structure example common to the liquid crystal panels shown in FIGS. 10 and 11 will be described with reference to FIG.
This will be described with reference to FIG. FIG. 12 shows a schematic plan structure of the liquid crystal panel 100, and FIG.
00 shows a schematic cross-sectional structure. Here, the above-described opposing substrates 40 and 60 and the element substrates 50 and 70 are
And an element substrate 101. The liquid crystal panel described below is particularly suitable when used as a liquid crystal panel for light modulation in a projection display device.

In the liquid crystal panel 100, an element substrate 101 made of glass or the like and a counter substrate 102 are bonded together with a predetermined gap (cell gap) via a sealing material 104, and are formed inside the sealing material 104. The liquid crystal 103 is injected into the liquid crystal sealing region 100a. The liquid crystal 103 is injected from a liquid crystal injection port 104a provided in the sealant 104, and the liquid crystal injection port 104a is thereafter closed by a sealing agent 105 made of a resin or the like. As the sealant 104, an epoxy resin or various photocurable resins can be used. In order to secure the cell gap, an inorganic or organic fiber or sphere having a particle size (about 2 to 10 μm) corresponding to the cell gap is mixed into the sealing material 104.

The element substrate 101 has a slightly larger surface area than the counter substrate 102, and active elements such as wiring layers, transparent pixel electrodes, and TFTs (thin film transistors) are formed on the inner surface thereof corresponding to a large number of pixels. . Transparent electrodes corresponding to pixels are also formed on the inner surface of the counter substrate 102. Outside the pixel array region on the inner surface of the counter substrate 102, a light-shielding film 102a formed in a circular shape inside the region where the sealant 104 is formed is formed.

Outside the formation region of the sealing material 104 on the inner surface of the element substrate 101, the element substrates 101 and 10
2, a wiring pattern 101a conductively connected to a wiring layer formed on the inner surface of the wiring pattern 1 is formed.
The scanning line driving circuit 107 and the data line driving circuit 108 are formed in accordance with 01a. Further, an outer edge portion on one side of the element substrate 101 is provided with an external terminal portion 101b in which a large number of external terminals 109 are arranged.
A wiring member such as the flexible wiring board 106 is conductively connected to b through an anisotropic conductive film or the like.

The liquid crystal 103 has a TN mode, an STN mode,
PS (in-plain switching) mode, VA (vertically
A liquid crystal panel suitable for various modes such as an aligned mode can be used. The liquid crystal panel 10
In the case of 0, the polarizing film, the retardation film, the polarizing plate, and the like are attached in a predetermined orientation according to the type of the liquid crystal 103 to be used, the operation mode, the display mode (normally white, normally black), and the like. .

Note that the microlens array of the present invention, the electro-optical device provided with the same, and the manufacturing method thereof are not limited to the above-described illustrated examples, but may be variously modified without departing from the gist of the present invention. Of course, changes can be made.

[0098]

As described above, according to the present invention,
By forming a concave groove on the back surface of the first transparent substrate from the slit hole by etching, the portion where the concave groove is formed on the first transparent substrate can be formed thinly, so that the groove is broken along the portion where the concave groove is formed. As a result, the structures of the microlens array can be separated from each other. Therefore,
Dicing does not need to be performed as in the related art, and the occurrence of chipping or the like can be prevented, or dicing can be performed more easily, so that the product yield can be improved.

[Brief description of the drawings]

FIG. 1 is a process explanatory diagram showing a first half of a schematic process of a first embodiment in a method for manufacturing a microlens array according to the present invention.

FIG. 2 is a process explanatory view showing the latter half of the schematic process of the first embodiment in the method of manufacturing a microlens array according to the present invention and a part of a method of manufacturing a liquid crystal device as a method of manufacturing an electro-optical device.

FIG. 3 is a process explanatory diagram showing a first half of a schematic process of a second embodiment in a method for manufacturing a microlens array according to the present invention.

FIG. 4 is a process explanatory view showing the latter half of the schematic process of the second embodiment in the method of manufacturing the microlens array according to the present invention and a part of the method of manufacturing the liquid crystal device as the method of manufacturing the electro-optical device.

FIG. 5 is a process explanatory view showing a schematic process in the first half of a third embodiment according to the present invention.

FIG. 6 is a process explanatory view showing a schematic process in the latter half of the third embodiment.

FIG. 7 is a process explanatory view showing a schematic process of a fourth embodiment according to the present invention.

FIG. 8 is a process explanatory view showing a schematic process of a fifth embodiment according to the present invention.

FIG. 9 is a graph (a) showing a composition ratio, an etching rate, and an etching selectivity of an etching solution composed of a mixed solution of hydrofluoric acid and ammonium fluoride, and an etching solution containing only hydrofluoric acid as a main component of etching. 4B is a graph (b) showing the relationship between the concentration of hydrofluoric acid and the etching rate.

FIG. 10 is an enlarged sectional view schematically showing the structure of the liquid crystal panel formed according to the first embodiment.

FIG. 11 is an enlarged cross-sectional view schematically illustrating a structure of a liquid crystal panel formed according to a third embodiment.

FIG. 12 is a schematic plan view showing the overall schematic plan structure of a liquid crystal panel formed by each of the above embodiments.

FIG. 13 is a schematic sectional view showing the overall schematic plan structure of the liquid crystal panel formed by each of the embodiments.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Glass substrate 10a ... Concave part 10b ... Concave groove 11 ... Mask layer 11a ... Pinhole 11b ... Slit hole 12 ... Coating layer 12b ... Slit hole 13 ... Transparent resin 14 ... Glass substrate 15 ... Light shielding layer 16 ... Transparent electrode 20 ... Lens Mold 21 ... Glass substrate 21b ... Concave groove 22 ... Transparent resin 22a ... Optical surface 23 ... Transparent resin 24 ... Glass substrate 25 ... Mask layer 25b ... Slit hole 30 ... Glass substrate 30b ... Concave groove 31 ... Protrusion 32 ... Transparent resin 33 ... Glass substrate 34 Mask layer 34b Slit hole 40 Counter substrate 50 Element substrate 51 Active element 52 Transparent pixel electrode 53 Liquid crystal 60 Counter substrate 70 Element substrate 71 Active element 72 Transparent pixel electrode 73 Liquid crystal

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H091 FA29Y FA34Y FC10 FC26 GA03 4G059 AA08 AB06 AB09 AB11 AC01 BB04 BB16 5G435 AA17 BB12 CC09 DD13 FF07 GG02 KK05 KK07

Claims (14)

[Claims] 1. An optical surface is formed on one surface of a first transparent substrate and a second transparent substrate, and a transparent material having a refractive index different from a material constituting the optical surface is provided on the optical surface. A method of manufacturing a microlens array in which the other one of the first transparent substrate and the second transparent substrate is joined via a first transparent substrate, wherein a front surface and a rear surface of the first transparent substrate are connected to a front surface of the first transparent substrate. A plurality of pinholes are arrayed and formed on an upper portion, and a portion on the back surface of the first transparent substrate is covered with a mask layer having an elongated slit hole. The transparent substrate is isotropically etched to form the concavely curved optical surface, and the first transparent substrate is etched through the slit holes to form a concave groove. Thereafter, the mask layer is etched. Before A portion on the surface of the first transparent substrate is removed, thereafter, the method of manufacturing a microlens array, wherein the thereby bonding the second transparent substrate via a transparent material on the optical surface. 2. The method according to claim 1, wherein after the first transparent substrate and the second transparent substrate are joined on the optical surface via the transparent material, the thickness of the second transparent substrate is reduced by an etching process. A method for manufacturing a microlens array. 3. An optical surface is formed on one of the first transparent substrate and the second transparent substrate, and a transparent material having a refractive index different from that of the material constituting the optical surface is provided on the optical surface. A method of manufacturing a microlens array in which the other one of the first transparent substrate and the second transparent substrate is joined through the first transparent substrate and the second transparent substrate via the transparent material via the transparent material. After bonding the second transparent substrate, the outer surface of the first transparent substrate is covered with a mask layer having etching resistance and having an elongated slit hole, and an etching process is performed in a state of being covered with the mask layer. A method of manufacturing a microlens array, comprising: reducing the thickness of the second transparent substrate and forming a concave groove on an outer surface of the first transparent substrate. 4. The small groove according to claim 3, wherein the etching time for forming the groove on the outer surface of the first substrate is shorter than the etching time for thinning the second substrate. A method for manufacturing a microlens array. 5. The method according to claim 1, wherein:
3. The method of manufacturing a microlens array according to claim 1, wherein the first transparent substrate is a glass substrate, and the etching is performed by wet etching using a mixed solution of hydrofluoric acid and ammonium fluoride. 6. The method according to claim 2, wherein the first transparent substrate and the second transparent substrate are glass substrates,
The method of manufacturing a microlens array, wherein the etching is performed by wet etching using a mixed solution of hydrofluoric acid and ammonium fluoride. 7. The mixed solution according to claim 5, wherein the weight ratio of hydrofluoric acid to ammonium fluoride is about 0.2 to 0.2.
6. A method for producing a microlens array, which is prepared and used so as to fall within the range of 6. 8. The method of manufacturing a microlens array according to claim 2, wherein the mask layer is formed of a polycrystalline silicon film, a silicon nitride film, or a silicon carbide film. 9. The method according to claim 8, wherein the mask layer is formed by a low-pressure CVD method. 10. The method according to claim 3, wherein the optical surface is formed by molding using a transparent material having a different refractive index from the transparent material. 11. The method of manufacturing a microlens array according to claim 10, wherein the mask layer is an amorphous silicon film, a metal film made of Pt or Au, or an alloy containing them. 12. The resist material according to claim 3, wherein the resist material arranged on the first transparent substrate is softened to form a convex curved surface, and an etching process is performed thereon. A method for manufacturing a microlens array, comprising: forming a convex curved optical surface corresponding to a curved surface shape on the first transparent substrate. 13. A microlens array is formed by the method of manufacturing a microlens array according to claim 1, and further, an electrode is formed on an inner surface of the second transparent substrate of the microlens array. And a method of manufacturing an electro-optical device, characterized in that another substrate provided with the other electrode facing the electrode is bonded. 14. The method for manufacturing an electro-optical device according to claim 13, wherein a light-shielding layer is formed on a surface of the second transparent substrate in a region corresponding to an interval between the optical surfaces.