JP2001242306A - Method of manufacturing microlens substrate and method of manufacturing electro-optic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a microlens substrate including a process of joining two transparent substrates through a transparent material and a process of reducing the thickness of at least one transparent substrate so that the microlens substrate can be efficiently manufactured without causing mechanical damages, warpage, distortion, cracks or chips of the transparent substrate to be processed into a thin material. SOLUTION: The outer surface of a glass substrate 14 (the upper face shown in the figure) not coated with a mask layer 11 or a coating layer 12 is immersed in an etching liquid as shown in Fig. (a) and etched so that the glass substrate 14 is made thin by etching as shown in Fig. (b). As for the etching treatment, a mixture solution of hydrogen fluoride and ammonium fluoride is used as the etching liquid.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing a microlens substrate and a method for manufacturing an electro-optical device.
Arrange and form a plurality of optical surfaces on the surface of one transparent substrate,
The present invention relates to a technique for manufacturing a microlens substrate in which this optical surface is bonded to another transparent substrate via a transparent material.

[0002]

2. Description of the Related Art Generally, as a method of manufacturing a microlens substrate, 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 of the microlens substrates formed as described above is mechanically ground and polished to reduce the thickness of the microlens substrate 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]

However, in the above-mentioned conventional method of manufacturing a liquid crystal panel, one of the glass substrates constituting the microlens substrate is ground or polished to make it thinner. However, it is difficult to process a plurality of microlens substrates at a time, so 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 will be formed on the surface of the glass substrate or that the glass substrate will be 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, if the glass substrate is made extremely thin, the substrate is likely to be cracked or chipped, so that the thickness of the glass substrate is limited, and it is difficult to make the microlens substrate 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 substrate 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 provide a manufacturing method which can efficiently manufacture a transparent substrate to be thinned without causing mechanical damage, cracking, chipping or the like on one of the transparent substrates.

[0008]

In order to solve the above-mentioned problems, a method of manufacturing a microlens substrate according to the present invention comprises forming an optical surface on at least one of a first transparent substrate and a second transparent substrate. A transparent material having a refractive index different from a material constituting the optical surface is provided on the optical surface through the first material.
A method for manufacturing a microlens substrate, comprising joining a transparent substrate and the second transparent substrate, wherein the first transparent substrate and the second transparent substrate are joined via the transparent material, and then etched. The thickness of the second transparent substrate is reduced.

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 substrate can be made thin without deteriorating the yield.

[0010] In the present invention, it is preferable that the etching treatment is performed in a state where the outer surface of the first transparent substrate is covered with a mask layer having etching resistance.

According to the present invention, by coating the outer surface of the first transparent substrate with the mask layer having etching resistance, it is possible to make only the second transparent substrate thin even if the entire microlens substrate is subjected to etching. Therefore, the etching process becomes easy, a large number of microlens substrates can be processed at a time, and the productivity can be improved, and mass production can be easily performed. Here, the first
The outer surface of the 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 a small etching rate such that the mask cover is not lost by the above-mentioned etching treatment, and having at least an etching rate smaller than that of the second transparent substrate. Say that.

In the present invention, it is preferable that the second transparent substrate is a glass substrate, and the etching is wet etching using a mixed solution of hydrofluoric acid and ammonium fluoride.

According to this invention, 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 the main component or hydrofluoric acid and other components are used. Since the etching rate with respect to the glass substrate can be extremely increased as compared with the case of using a mixed solution of the second transparent substrate, the second transparent substrate can be processed quickly into a thin wall.

In the present invention, the mixed solution is preferably prepared and used so that the volume 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 volume ratio between 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 these are easily etched. It can be easily formed by a phase growth method or the like.

In the present invention, the mask layer may be 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, both surfaces of the first transparent substrate are covered with a mask layer, and a plurality of openings are arranged and formed in the mask layer covering the first surface of the first transparent substrate. The first transparent substrate is isotropically etched to form the concavely curved optical surface, the mask layer on the first surface is removed, and then the transparent material is interposed on the optical surface. In some cases, the second transparent substrate is bonded.

In the present invention, it is preferable that the mask layer on the first surface is formed simultaneously with the same material as the mask layer coated on the second surface on the back surface of the first surface.

Since the first surface mask layer of the first transparent substrate is formed simultaneously with the same material as the second surface mask layer, both mask layers are simultaneously formed in the same step, and then the opening is formed. Forming an optical surface with the provided first surface mask layer;
Thereafter, the mask layer on the first surface is removed, and the second transparent substrate is bonded to the optical surface via a transparent material, whereby the second
When etching the transparent substrate, the second surface of the first transparent substrate can be processed as it is because the mask layer has already been formed on the second surface. Since the step of forming only the mask layer covering the second surface of one transparent substrate is not required, the manufacturing process can be simplified. In the present invention, when the mask layer on the first surface and the mask layer on the second surface are simultaneously formed, only the mask layer on the first surface is removed without removing the mask layer on the second surface. In some cases, it is necessary to form an additional coating layer on the mask layer on the second surface in order to remove the coating layer. In this case, the coating layer must be left at least until the etching step for the second transparent substrate. Thereby, the first transparent substrate can be reliably protected from the etching process. Therefore,
The mask layer itself can be formed thin.

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 mixture of these materials. It is preferable that the film be a film that can be formed at a low temperature, such as a metal film made of a containing alloy. In this case, the mask layer is made of an amorphous silicon film or P
Since a low-temperature film formation method such as a sputtering method can be used by forming a metal film or the like made of t or Au or an alloy containing these, particularly in the case of the method described in claim 9, a transparent material is used. The film can be formed without any trouble even if a resin having relatively low heat resistance is used.

In the present invention, the surface of the resist material arranged on the first transparent substrate is softened to form a convex curved surface, and the surface of the resist material is subjected to dry etching to thereby form the convex curved surface of the resist material. In some cases, the optical surface having a convex curved surface corresponding to the above is formed on the first transparent substrate.

According to a method of manufacturing an electro-optical device of the present invention, a microlens substrate is formed by the above-described method of manufacturing a microlens substrate, and further, an electrode is formed on the inner surface of the second transparent substrate of the microlens substrate. 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, the surface of the second transparent substrate is hardly mechanically damaged. 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 on the microlens substrate can be introduced into the center of the pixel and emitted after being modulated. The light intensity and the quality of the emitted light can be compatible. 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.

[0032]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of a method for manufacturing a microlens substrate according to the present invention will be described in detail with reference to the accompanying drawings. Although each embodiment described below relates to a microlens substrate used as a part of a liquid crystal panel, the present invention is not limited to a liquid crystal panel,
In particular, it is preferably used for various electro-optical devices, for example, those provided with various electro-optical panels such as an EL (electroluminescence) panel and an organic EL panel, and is not limited to those used for the above-mentioned electro-optical devices. ,
The present invention can be applied to the manufacture of a microlens substrate widely used for various purposes.

[First Embodiment] FIGS. 1 and 2 are process explanations showing a method of manufacturing a microlens substrate 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, as shown in FIG. 1A, first, a low-pressure C
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 openings 11a are formed in the mask layer 11 on one surface (the upper surface in the figure) of the glass substrate 10. These plural openings 11a
Is formed on the mask layer 11 by a patterning technique such as a photolithography method or a perforation technique using laser light irradiation. The openings 11a are arranged in accordance with the arrangement of the optical centers of the microlenses on the microlens substrate to be manufactured. As can be seen from the drawing, the portion of the mask layer 11 on the upper surface of the drawing where the opening 11a is formed functions only as the above-described resist layer. The diameter of the opening 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 to 25 μm.

Next, as shown in FIG. 1C, a concave portion 10a having a substantially hemispherical concave curved surface is formed by subjecting the glass substrate 10 to wet etching. 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 this embodiment, a substantially hemispherical concave portion 10a having a circular contour in plan view is formed on the surface of the glass substrate 10.
However, depending on the shape of the opening 11a, the outline shape is not limited to a circular shape, but may be formed in various shapes such as a rectangle and a square. The diameter of the concave portion 10a varies depending on the purpose and field of use of the microlens substrate, but is, for example, 1 to 100 μm, preferably 10 to 50 μm.
It is about. Electro-optical devices, particularly those used for liquid crystal devices, are formed to have substantially the same size as each pixel region.

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, a coating layer 12 having etching resistance is formed on the side surface and the back surface (the lower surface in the drawing) of the glass substrate 10, and the mask layer 11 formed on the side surface and the back surface is left without being removed. The removal of the mask layer 11 made of a polycrystalline silicon film is performed using an aqueous solution of an organic alkali such as TMAH or an aqueous solution of an inorganic alkali such as aqueous ammonia or potassium hydroxide. In the case of a silicon nitride film, it can be removed by phosphoric acid or the like. 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. When only the mask layer 11 on the front side can be removed by strong anisotropic dry etching or the like, the covering layer 12 is unnecessary.

In FIG. 1D, the mask layer 11 may be entirely removed, and the covering surface 12 may be formed except for the surface side.

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 photocurable resin (adhesive) such as an acrylic resin or an epoxy resin can be used. In this bonding step, a transparent resin 13 is applied on the concave portion 10a of the glass substrate 10 in a vacuum, for example, in order to prevent air bubbles from being mixed, and a glass substrate 14 is adhered from above, and pressed. 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 0.6 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 result is a very thick microlens. In this embodiment, the glass substrate 14 is immersed in an etchant in the state shown in FIG. 2A to etch the outer surface (the upper surface in the drawing) of the glass substrate 14 which is not covered by the mask layer 11 and the coating layer 12. It is thinner.

In this embodiment, a mixed aqueous solution of hydrogen fluoride and ammonium fluoride is used as the etching solution in the above-described etching process. In this etching solution, since the dissociation of ions represented by NH ₄ F → NH ₄ ⁺ F ⁻ (1) occurs at a rate close to 100%, the equation of HF + F ⁻ → HF ₂ ⁻ (2) HF ₂ formed by ^- ions contribute 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 by the following equation: SiO ₂ + 2HF ₂ ⁻ + 2H ₃ 0 ⁺ → SiF ₂ ⁻ + 4H ₂ O (3) The relationship between the composition ratio and the etching rate in this case is shown in FIG. 5A as described later.

Incidentally, H ₃ O ⁺ _{is, 2HF + H 2 0 → HF} 2 - those caused by two equations ^{_{(5) - + H 3 0}} + (4) 2H 2 0 → H 3 0 + + OH .

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 ⁻ (6) is extremely large. small, as a ^{result, HF - + F - → HF} 2 - HF formed by the formula (7) ₂ ^- for ion concentration very small, the etching rate for the glass is low. FIG. 5B shows the relationship between the HF concentration and the rate in the etching solution composed 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. 5A, the horizontal axis represents the volume ratio of 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. 5A, the solid line in the drawing shows the etching rate, and the broken line in the drawing 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.
Since the thickness is as thin as possible, even if the etching is performed while leaving the coating layer 12 as it is, if the etching selectivity is low, the mask layer 11 must be thickened. 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, FIG.
As shown in (a), the volume ratio between hydrofluoric acid and ammonium fluoride is generally preferably about 0.2 to 6. Further, when importance is placed on the etching selectivity, the mask layer 11 may be used. When the thickness is reduced, it 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 means an aqueous solution of hydrogen fluoride having a concentration of 50%.

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 may be 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 substrate composed of the glass substrate 10, the transparent resin 13, and the glass substrate 14 is formed. Although the microlens substrate can be used for various purposes, in the present embodiment, a glass substrate 14 constituting the microlens substrate is used as one liquid crystal panel substrate to form a liquid crystal panel incorporating the microlens substrate. are doing.

Next, as shown in FIG. 2C, the mask layer 11 and the coating layer 12 that have been adhered to the outer surface of the glass substrate 10 are removed. This removal is performed by etching the mask layer 11 with an aqueous alkali solution or the like in the same manner as described above.
It can be removed by dry etching, a mixed aqueous solution of sulfuric acid and aqueous hydrogen peroxide or ammonia water and aqueous hydrogen peroxide, or the like.

Finally, when a liquid crystal panel described later is formed by using the microlens substrate 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 in a lattice shape in a region between the lens portions (formed by the concave portions 10a) of the microlens substrate. 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.

Here, the mask layer 1 is formed from the outer surface of the glass substrate.
1 and the coating layer 12, the light-shielding layer 5, the transparent electrode 1
The reason for forming 6 is to prevent the transparent electrode 16 from being etched by the etchant for etching the mask layer 11 and the coating layer 12.

When there is no possibility that the etching solution for etching the mask layer 11 and the coating layer 12 will etch the transparent electrode, the light shielding film 15 and the transparent electrode 16 are formed while leaving the mask layer 11 and the coating layer 12 as they are. You may. In this case, there is an effect that dust can be prevented from adhering to the glass substrate 10 or being scratched. Further, the outer surface of the glass substrate 10 may be covered with the mask layer 11 and the covering layer 12 until there is no particular problem in the subsequent steps.
After the formation of the transparent electrode 5 and the transparent electrode 16, a glass substrate having a transparent electrode or the like formed on the inner surface thereof at a predetermined interval (for example, 3 to 10 μm) is bonded to the laminate by a sealing material (not shown). A liquid crystal panel may be formed by injecting liquid crystal into the inside and then removed.
Further, if dicing is performed in a state where the glass substrate 10 is covered with the mask layer 11 and the coating layer 12, the mask substrate 11 and the coating layer 12 are removed after the dicing step, so that the glass substrate 10 is hardly damaged. .

In this embodiment, since the glass substrate 14 is thinned by etching, for example, a large number of microlens substrates can be processed simultaneously and 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.

Also, by forming polycrystalline silicon, silicon nitride, silicon carbide, or the like by a low-pressure CVD method, 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.

In this embodiment, the glass substrate 10
Although the description has been made using the example in which the optical surface is formed only on the substrate, the optical surface may be formed on the glass substrate 14 as well.

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

In this embodiment, as shown in FIG. 3A, first, a lens mold 20 formed by molding a semiconductor material such as various metals and 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. 3B, a transparent resin 23 is applied to the surface on the side of the optical surface 22a, and a glass substrate 24 is bonded thereon. As shown 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. 3C, 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 is made of amorphous silicon, Pt, Au, or an alloy thereof (eg, an Au—Cr alloy) instead of the polycrystalline silicon, silicon nitride, silicon carbide, or the like described in the first embodiment, and is formed by sputtering. It is preferably formed by a low-temperature film formation method such as a method.
Here, the mask layer 25 is made of the transparent resin 22 and the transparent resin 23.
The mask layer 25 is preferably formed to extend to the side surface of the transparent resin 2 on the glass substrate 24.
It may be formed to extend to the side surface near the interface with No. 3.
After forming the mask layer 25, the outer surface (the upper surface in the figure) of the glass substrate 24 is removed by etching, and the thickness is reduced as shown in the figure. This etching method is exactly the same as in the case of the first embodiment.

Next, the mask layer 25 is removed, and finally, as shown in FIG. 3D, a light-shielding layer 26 and a light-shielding layer similar to those of the first embodiment are formed on the surface of the glass substrate 24 thinned by etching. The transparent electrode 27 is formed.

The timing for removing the mask layer 25 is not limited to the above timing, but may be an appropriate timing as in the first embodiment.

In this embodiment, basically the same effects as in the first embodiment can be obtained. However, since the optical surface 22a is formed 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.

Although the present embodiment has been described using an example in which the optical surface is formed only on the transparent resin 22, the optical surface may be formed on the glass substrate 24.

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

In this embodiment, as shown in FIG. 4A, a projection 31 is formed on a glass substrate 30 so as to protrude into a convex curved surface shown by a dotted line in the drawing. 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 projections 31 by, for example, a dry etching method, and the projections 31 are eventually completely lost, 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. 4B, 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. 4C, 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.
Thereafter, the outer surface (the upper surface in the figure) of the glass substrate 33 is etched by etching, and the glass substrate 33 is thinned. This etching step is performed in exactly the same manner as in the first embodiment.

Next, the mask layer 34 is removed, and finally, as shown in FIG. 4D, 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. I do.

The timing for removing the mask layer 34 is not limited to the timing described above, but may be an appropriate timing as in the first embodiment. Also in this embodiment, the same effects as those of the above embodiments can be obtained.

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, the isotropy of etching is increased when forming the optical surface, so that the optical surface of the microlens can be formed into 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.

In this embodiment, the glass substrate 30
Although the description has been made using the example in which the optical surface is formed only on the substrate, the optical surface may be formed on the glass substrate 33 as well.

[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. 6 shows a structure of an active matrix type liquid crystal panel formed using the structure formed in the first embodiment as a counter substrate 40.
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. And the counter substrate 4
The liquid crystal panel is formed by bonding the element substrate 50 to the substrate 0 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. 7 shows a structure of a liquid crystal panel using the structure formed according to the second embodiment as a counter substrate 60. In this liquid crystal panel, FIG.
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. Then, the opposing substrate 60 and the element substrate 70 are bonded via a sealing material (not shown), and a liquid crystal 73 is injected therebetween.
Note that the liquid crystal 7 of each of the opposing substrate 60 and the element substrate 70 is
An alignment film (not shown) is formed on the opposing inner surface in contact with 3.

Also in this liquid crystal panel, similarly to the above, light incident from the counter substrate 60 side is condensed by the micro lens, 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, an overall configuration of a panel structure example common to the liquid crystal panels shown in FIGS. 6 and 7 will be described with reference to FIGS. 8 and 9. FIG. 8 shows a schematic plan structure of the liquid crystal panel 100, and FIG. 9 shows a schematic cross-sectional structure of the liquid crystal panel 100. Here, the opposing substrates 40 and 60 and the element substrates 50 and 70 are shown as an opposing substrate 102 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 an opposing 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 surface area slightly larger than that of 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 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 sealant 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. .

Incidentally, the microlens substrate of the present invention, the electro-optical device provided with the same, and the method of manufacturing these 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.

[0083]

As described above, according to the present invention,
By making the second transparent substrate thinner by the etching process, mechanical damage may be caused on the second transparent substrate,
The second transparent substrate can be made thinner than before without causing cracking or chipping of the substrate or causing bending or distortion of the glass substrate, so that the microlens substrate can be produced without deteriorating the yield. Can be made thinner.

[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 substrate 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 substrate 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 view showing a schematic process of a second embodiment according to the present invention.

FIG. 4 is a process explanatory view showing a schematic process of a third embodiment according to the present invention.

FIG. 5 is a graph (a) showing a composition ratio, an etching rate, and an etching selectivity of an etching solution composed of a mixture 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. 6 is an enlarged sectional view schematically showing the structure of the liquid crystal panel formed according to the first embodiment.

FIG. 7 is an enlarged sectional view schematically showing the structure of a liquid crystal panel formed according to a second embodiment.

FIG. 8 is a schematic plan view showing the overall schematic plan structure of the liquid crystal panel formed by each of the above embodiments.

FIG. 9 is a schematic cross-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 11 ... Mask layer 11a ... Opening 12 ... Resist layer 13 ... Transparent resin 14 ... Glass substrate 15 ... Light shielding layer 16 ... Transparent electrode 20 ... Lens type 21 ... Glass substrate 22 ... Transparent tree plate 22a ... Optical Surface 23 ... Transparent resin 24 ... Glass base 25 ... Mask layer 30 ... Glass substrate 31 ... Protrusion 32 ... Transparent resin 33 ... Glass substrate 34 ... Mask layer 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) 2H090 JA04 JB02 JC03 LA01 LA04 LA05 2H091 FA27X FA34Z FC01 FC26 FD14 GA01 GA02 GA13 GA17 LA02 LA12 LA17 LA19

Claims (13)

[Claims] An optical surface is formed on a surface of at least one 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 substrate, comprising joining the first transparent substrate and the second transparent substrate via a substrate, wherein the first transparent substrate and the second transparent substrate are joined via the transparent material. After the above, the second
A method for manufacturing a microlens substrate, comprising thinning a transparent substrate. 2. The method of manufacturing a microlens substrate according to claim 1, wherein the etching process is performed while an outer surface of the first transparent substrate is covered with a mask layer having etching resistance. 3. The method according to claim 1, wherein the second transparent substrate is a glass substrate, and the etching is performed by wet etching using a mixed solution of hydrofluoric acid and ammonium fluoride. A method for manufacturing a microlens substrate. 4. The microlens substrate according to claim 3, wherein said mixture is prepared so that the volume ratio of hydrofluoric acid to ammonium fluoride is in the range of about 0.2 to 6. Manufacturing method. 5. The method of manufacturing a microlens substrate according to claim 2, wherein the mask layer is formed of a polycrystalline silicon film, a silicon nitride film, or a silicon carbide film. 6. The method according to claim 5, wherein the mask layer is formed by a low pressure CVD method. 7. The method according to claim 2, wherein both surfaces of the first transparent substrate are covered with a mask layer, and the first surface of the first transparent substrate is covered. A plurality of openings are arrayed and formed in the mask layer, and the first transparent substrate is isotropically etched from the openings to form the concavely curved optical surface, and the mask layer on the first surface is removed. And
Thereafter, the second transparent substrate is bonded to the optical surface via the transparent material, the method for manufacturing a microlens substrate. 8. The method according to claim 7, wherein the mask layer on the first surface is formed simultaneously with the same material as the mask layer coated on the second surface on the back surface of the first surface. A method for producing a microlens substrate. 9. Any one of claims 1 to 6
9. The method for manufacturing a microlens substrate according to item 1, wherein the optical surface is formed by molding using a transparent material having a refractive index different from that of the transparent material. 10. The etching process according to claim 9, wherein the etching process is performed in a state in which 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 metal film made of an alloy containing these. 11. The resist material according to claim 1, wherein the resist material arranged on the first transparent substrate is softened to form a convex curved surface, and the dry material is dried from above. A method of manufacturing a microlens substrate, wherein the optical surface having a convex curved surface corresponding to the convex curved surface shape of the resist material is formed on the first transparent substrate by performing an etching process. 12. A microlens substrate is formed by the method of manufacturing a microlens substrate according to claim 1, and further, an electrode is formed on an inner surface of the second transparent substrate of the microlens substrate. And a method of manufacturing an electro-optical device, characterized in that another substrate provided with the other electrode facing the electrode is bonded. 13. The method for manufacturing an electro-optical device according to claim 12, 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.