JP4293802B2 - Manufacturing method of substrate with microlens, manufacturing method of counter substrate of liquid crystal display panel, and manufacturing method of liquid crystal panel - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for manufacturing a substrate with a microlens in which a microlens is formed on a translucent substrate, a method for manufacturing a counter substrate of a liquid crystal panel using the microlens, and a method for manufacturing a liquid crystal panel.
[0002]
[Prior art]
Conventionally, a projection type liquid crystal display device such as a liquid crystal projector using a liquid crystal panel is known. A liquid crystal panel used in a projection-type liquid crystal display device includes a drive substrate on which a plurality of pixel electrodes and a switching element for driving the pixel electrode are formed, and a substrate provided opposite to the drive substrate. A counter substrate having a counter electrode formed at a position facing the pixel electrode, and liquid crystal is present between the drive substrate and the counter substrate. When the switching element is controlled based on the image signal, the power applied to the liquid crystal between the two electrodes is controlled.
[0003]
As a result, the transmission state of the light incident from the counter substrate side, passing through each pixel portion and emitted from the drive substrate side is controlled by the liquid crystal, and a projection image based on the image signal is created. In such a liquid crystal panel, in order to prevent harmful light from hitting the switching element of the driving substrate, the light shielding film is formed on the portion of the counter substrate facing the switching element. A so-called black matrix, which is a pattern, may be provided on the counter substrate.
[0004]
In recent years, with such high-definition liquid crystal display devices, in order to efficiently use light that has not conventionally contributed to display by being incident on a position corresponding to a black matrix or a switching element, a counter substrate is used. As described above, a substrate with a microlens array on which a microlens array is formed has been used.
[0005]
That is, when the microlens array is not used, when projection light is incident from the counter substrate side, a part of the light hits the black matrix or the switching element and is not used as light for forming a projection image. Was wasted. For this reason, it was disadvantageous in improving the brightness of the projected image. Therefore, a microlens array is formed on the counter substrate, and when there is no lens, the portion of light that should have been incident on the black matrix or the like is collected and allowed to pass through the pixel portion.
As a result, the transmission state of the light incident from the counter substrate side, passing through each pixel portion and emitted from the drive substrate side is controlled by the liquid crystal, and a projection image based on the image signal is created.
[0006]
As a method for manufacturing such a substrate with a microlens array, a mask having a predetermined opening is provided on the substrate, and the substrate is wet-etched from the opening to form a hemispherical recess in the substrate. Conventionally, a method of forming a hemispherical microlens by filling a resin having a different refractive index and providing a cover glass on the resin is known (see, for example, Patent Document 1).
[0007]
However, the microlens array formed in a hemispherical shape has a large aberration at the outer peripheral portion of each microlens, that is, the boundary portion between adjacent individual microlenses, and high contrast and high brightness cannot be obtained. There was a problem. In order to solve this problem, the aberration at the outer peripheral portion of the lens is reduced by combining the shape of the concave portion with two curvatures of the central portion and the outer peripheral portion having a larger radius of curvature than the central portion. Has been proposed. In addition, as a method of manufacturing this microlens, a mask having an opening is formed on the substrate, first, dry etching is performed on the substrate so that etching in the depth direction is increased, and then the same opening is masked. A method of performing isotropic wet etching has been proposed (see, for example, Patent Document 2).
[0008]
[Patent Document 1]
JP 2000-235105 A
[Patent Document 2]
Japanese Patent Laid-Open No. 2002-6113
[0009]
[Problems to be solved by the invention]
By the way, in the manufacturing method described in Patent Document 2 described above, anisotropic dry etching is indispensable in order to obtain a desired concave shape having a curved surface with a different radius of curvature at the central portion and the outer peripheral portion. However, dry etching has a drawback in that it requires a large amount of equipment as compared with conventional concave etching by wet etching. Further, since the etching efficiency is low, the throughput is lowered and the cost is increased.
[0010]
Furthermore, when etching a substrate having a large area, etching unevenness and surface roughness are likely to occur depending on the location, and a uniform lens shape may not be obtained over the entire surface of the substrate. As a result, the yield is lowered and uniform lens performance cannot be obtained. As a result, for example, when used as a liquid crystal panel, it may cause image unevenness.
[0011]
As described above, when the dry etching process is used for forming the concave portion, the substrate with the microlens array is expensive, and it is difficult to obtain uniform lens performance. When used as a liquid crystal display device, as a result, a liquid crystal display device is obtained. There is a problem that it causes high cost and performance degradation.
[00012]
The present invention has been made under the above-described background, and provides a method of manufacturing a substrate with a microlens having a microlens having a shape capable of reducing aberrations in an outer peripheral portion without using a dry etching process. Furthermore, it is an object of the present invention to provide a method for manufacturing a counter substrate of a liquid crystal panel using the substrate with microlenses and a method for manufacturing a liquid crystal panel.
[0013]
[Means for Solving the Problems]
As means for solving the above-mentioned problem, the first means is:
A concave portion forming step of forming a large number of concave portions having a lens shape on the translucent substrate; and a microlens forming step of forming a microlens portion by filling the concave portion with a medium having a refractive index different from that of the substrate. A method of manufacturing a substrate with a microlens,
The concave forming step includes
A mask layer having an opening is formed at a position where the concave portion is formed on the surface of the translucent substrate, an etching solution is brought into contact with the surface of the translucent substrate exposed through the opening, and the translucent substrate is etched. A first etching step for forming a first recess;
A second etching opening for enlarging the opening of the mask layer and exposing an unetched substrate surface around the first recess to form an opening for a second etching to be performed next Part forming step;
The translucent substrate is etched by bringing an etchant into contact with the surface of the translucent substrate exposed by the second etching opening forming step and the inner surface of the recess formed by the first etching. A second etching step for forming a second recess having a surface composed of a plurality of different curved surfaces;
A method for manufacturing a substrate with a microlens, comprising:
The second means is
In the second etching opening forming step, the mask layer erodes the inner side surface of the opening of the mask layer in a state where the upper surface of the mask layer is protected by the protective member, but the protective member and the light transmitting member The method for producing a substrate with a microlens according to the first means is characterized in that the conductive substrate is etched by being brought into contact with an etching solution that does not erode.
The third means is
When parallel light is incident from one surface side of the substrate with microlenses manufactured by the method for manufacturing a substrate with microlenses according to the first or second means, the light is converged and formed by the action of the microlenses. And a step of providing a transparent electrode layer on the other surface side of the substrate with microlenses at a position on the optical path of the light beam.
The fourth means is
A counter substrate of a liquid crystal panel manufactured by a method for manufacturing a counter substrate of a liquid crystal panel according to a third means;
Pixel electrodes provided in a matrix on a light-transmitting substrate so as to correspond to the microlenses and transparent electrode layer of the counter substrate of the liquid crystal panel, and switching elements provided corresponding to the respective pixel electrodes A drive board having
The position of the microlens and the transparent electrode layer of the counter substrate of the liquid crystal panel and the position of the pixel electrode and the switching element of the drive substrate are in a predetermined positional relationship, and the counter substrate and the drive substrate of the liquid crystal panel Are arranged opposite each other with a predetermined gap,
A liquid crystal panel manufacturing method, wherein a liquid crystal layer is held and fixed between a counter substrate and a driving substrate of the liquid crystal panel.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is an explanatory view of a method for manufacturing a substrate with microlenses according to an embodiment of the present invention. FIG. 2 is a cross-sectional view of the substrate with microlenses manufactured by the method for manufacturing a substrate with microlenses according to an embodiment of the present invention. 3 is a plan view of the substrate with microlenses manufactured by the method for manufacturing the substrate with microlenses according to the embodiment of the present invention. FIG. Hereinafter, first, a substrate with a microlens manufactured by the method for manufacturing a substrate with a microlens according to an embodiment of the present invention will be described with reference to FIGS. 2 and 3, and then the present invention will be described with reference to FIG. The manufacturing method of the board | substrate with a microlens concerning embodiment of this is demonstrated.
[0015]
As shown in FIG. 2, this microlens-equipped substrate 100 is obtained by forming a large number of microlenses 10, 10,... On one surface side of a translucent substrate 1 such as glass. The microlens 10 is formed by forming a large number of recesses (12) on one surface side of the substrate 1 and filling the recesses with a material having a higher refractive index than that of the material of the translucent substrate 1. Further, the concave portion is filled with a medium having a refractive index different from that of the substrate (a material having a higher refractive index than the substrate), and the cover member made of a translucent material is brought into contact with the medium while the medium is present on the substrate surface. You may fix so that the said medium may be pinched | interposed with the said translucent board | substrate and the said cover member. Specifically, for example, the resin 4 is applied so as to fill the recess (12), and the cover glass 5 is placed thereon and cured to form. The microlenses 10 thus formed converge parallel light incident from the side opposite to the cover glass 5 of the substrate 1 on the cover glass 5 side.
[0016]
Roughly speaking, the surface shape of the concave portion (12) is such that the surface shape of the central region of the concave portion forms the first curved surface 12a, and the surface shape of the peripheral region forms the second curved surface 12b. However, in practice, the first curved surface 12a is a flat surface in the central region, and the surface shape of the peripheral region continuously connected from the flat flat surface portion is a spherical shape. In this case, the curvature radius of the second curved surface 12b is formed larger than the curvature radius of the spherical surface in the peripheral region of the first curved surface 12a.
[0017]
By adopting such a shape, the aberration in the peripheral portion of the microlens 10 is reduced. At the same time, when adjacent microlenses are arranged close to each other, the overlapping of the peripheral portions of each other can be reduced. Thus, a larger area of the substrate can be filled with the microlens, and more of the light incident on the substrate can be effectively condensed by the microlens.
[0018]
For this reason, the individual microlenses are arranged close to each other so that the peripheral portions of the adjacent microlenses 10 have portions overlapping each other. As a result, as shown in the plan view of FIG. 3, the microlens-equipped substrate 100 has a shape of each microlens in a plan view that is close to a polygonal shape rather than a circular shape. .
[0019]
Next, a method for manufacturing a substrate with a microlens according to an embodiment of the present invention will be described with reference to FIG. The manufacturing method of the substrate with microlenses according to the embodiment includes (a) formation of a mask layer and a resist layer, (b) formation of a first etching opening, (c) first etching, and (d) second. It consists of the steps of etching opening formation, (e) second etching, (f) residual layer removal and lens formation. Hereinafter, these steps will be described.
[0020]
(A) Mask layer and resist layer forming step (see FIG. 1A)
In this step, a mask layer 2 used as a mask for etching the substrate 1 and a resist layer 3 used for pattern formation on the mask layer 2 by a photolithography method are formed on the translucent substrate 1. Is a step of forming. As the light-transmitting substrate 1, a material that transmits light to be used and can be processed by wet etching is used. For example, quartz glass, oxide glass, alkali-free glass, crystallized glass, or the like is used.
[0021]
When the substrate 1 is used as a counter substrate for a liquid crystal display device, the same material as that of the driving substrate or a material having a thermal expansion coefficient close to that of the driving substrate is selected for matching of the thermal expansion coefficient. In order to form a uniform recess according to the design, the main surface of the substrate is polished to a predetermined flatness and surface roughness. Of course, it should be in a state without scratches.
[0022]
The material of the mask layer 2 may be any material that has etching resistance to the etching solution of the substrate 1 and can be patterned. For example, when the substrate 1 is glass, one containing hydrofluoric acid is used as the etching solution. Examples of materials having resistance to such an etchant include metals such as Cr and Ti or alloys containing these metals, such as oxides, nitrides, carbides of these metals, polycrystalline silicon, and amorphous silicon. Can be mentioned. The thickness of the mask layer 2 is required to be more than a sufficient mask function for the etching time required to form a desired lens shape on the substrate 1. The mask layer 2 is formed by sputtering or other known thin film forming techniques. The resist layer 3 only needs to be capable of forming a pattern with respect to the mask layer 2 by a known photolithography method. The application can also be performed by a known method such as a spin coating method.
[0023]
(B) First etching opening forming step (see FIG. 1B)
This step is a step of forming a large number of openings 20 in the mask layer 2 using a known photolithography method. The opening 20 is an opening for forming the recess 11 in the substrate 1 by etching. The opening 20 is formed by forming a fine circular hole or a polygonal hole in the mask layer 2 at a position to be the center of the microlens 10 to be formed. That is, the resist layer 3 is exposed to an opening pattern and developed to form an opening pattern. Next, using this as a mask, the mask layer 2 is etched to form an opening 20 in the mask layer 2. The opening 20 is usually circular in plan view, but may be polygonal or other shapes. The size is about several μm to several tens of μm in diameter.
[0024]
(C) First etching (see FIG. 1C)
This step is a step of etching the substrate 1 using the mask layer 2 and the resist layer 3 in which the openings 20 are formed as a mask to form a large number of first concave portions 11 having a desired hemispherical shape and having a desired size. is there. As the etching solution, when the substrate 1 is glass, a solution containing a strong acid such as hydrofluoric acid, hydrochloric acid, or sulfuric acid is used. For example, as an aqueous solution containing hydrofluoric acid, hydrofluoric acid, a mixed liquid of hydrofluoric acid and ammonium fluoride, a solution obtained by adding an alcohol such as glycerin to hydrofluoric acid, or the like is used.
[0025]
(D) Formation of second etching opening (see FIG. 1D)
This step is a step of expanding the diameter of the opening 20 formed in the mask layer 2 and forming the opening 21 which is the second etching opening for performing the second etching. In this step, the resist layer 3 and the substrate 1 are removed. erosion Without mask layer 2 only erosion The etching solution is performed by contacting the inner side surface of the opening 20. Specifically, the surface of the substrate 1 on the side where the mask layer 2 and the opening 20 are formed is immersed in an etching solution, or the etching solution is sprayed toward the inner side surface of the opening 20.
[0026]
The step of forming the opening 21 by expanding the diameter of the opening 20 is such that at least the edge 1a that is the boundary between the first recess 11 formed by the first etching and the surface of the substrate 1 is completely exposed. Do until. And it continues until a part of substrate surface of the outer side area | region of the edge 1a of the recessed part 11 is exposed. However, the mask layer 2 is always left between adjacent microlenses.
[0027]
(E) Second etching (see FIG. 1 (e))
In this step, the mask layer 2 and the resist layer 3 formed in the opening 21 are used as a mask to further etch the first recess 11 and the portion exposed by the diameter expansion of the opening 20, thereby forming the second recess 12. Is a step of forming. The same etching solution as that used in the first etching can be used as the etching solution, but a different concentration or a different etching solution may be used as necessary.
[0028]
By this second etching, etching proceeds from the surface of the first recess 11 and the surface of the substrate 1 exposed by expanding the diameter of the opening 20 and forming the opening 21. In this second etching, the etching amount is set to be larger than that of the first etching in order to deepen the central portion. As for the 2nd recessed part 12 formed by this etching, the area | region of the center part has comprised the 1st curved surface 12a, and the area | region of the outer peripheral part has comprised the 2nd curved surface 12b. In practice, the first curved surface 12a is a flat surface in the central region, and the surface shape of the peripheral region continuously connected from the flat flat surface portion is spherical. In this case, the curvature radius of the second curved surface 12b is formed larger than the curvature radius of the spherical surface in the peripheral region of the first curved surface 12a.
[0029]
(F) Residual layer removal and lens formation (see FIG. 1 (f))
In this step, the mask layer 2 and the resist layer 3 remaining after the second etching are removed. Next, a resin having a refractive index different from the refractive index of the substrate 1 is applied to the surface of the substrate 1 so that the resin completely fills the second recess 12, and at the same time, the resin layer 4 is formed on the substrate 1. To. Further, a cover member 5 made of a translucent material is bonded onto the resin layer 4. Thereby, the part by which the recessed part 12 was filled with resin becomes the lens part 10, and the board | substrate with a microlens is obtained.
[0030]
In this case, as the resin to be used, in this embodiment, a resin having a refractive index higher than that of the substrate 1 is used. Further, if an ultraviolet curable resin is used as this resin, it is advantageous because a thermal process is not required for curing. A resin having good adhesion to the substrate is desirable. Furthermore, in order to prevent voids from forming in the resin filled in the recesses 12, it is preferable to use a resin having a small volumetric shrinkage during curing. As a resin that satisfies the above conditions, there is an acrylic ultraviolet curable resin. For adjusting the refractive index, a mixture of a plurality of types of resins may be used.
[0031]
As the cover member 5, thin glass or the like can be used. In addition, it is preferable to use the same material as that of the substrate 1 or a material having a similar thermal expansion coefficient for matching the thermal expansion coefficients. The cover member may be joined simultaneously with the formation of the resin layer 4. For example, after applying the resin, the cover member 5 may be applied to the resin and the resin may be cured to bond using the adhesive force of the resin itself. After the cover member 5 is joined, the surface of the cover member 5 or the back side of the substrate 1 on which the cover member 5 is not formed is polished as necessary.
[0032]
FIG. 4 is an explanatory view of the method for manufacturing the counter substrate of the liquid crystal panel according to the embodiment of the present invention. As shown in FIG. 4, the counter substrate 200 of the liquid crystal panel has a light shielding film pattern 6 called a so-called black matrix formed on the cover member 5 of the above-described substrate 100 with microlenses, and a transparent electrode 7 formed thereon. Formed. In the light shielding film pattern 6, a light shielding film is arranged at a position corresponding to between adjacent microlenses 10. Thereby, the parallel light L incident on the substrate 1 from the side opposite to the side on which the transparent electrode 7 is formed is collected by each microlens 10 and passes through a portion of the light shielding film pattern 6 where the light shielding film is not formed. To converge.
[0033]
That is, the light-shielding film pattern 6 and the microlens 10 have the above-described light-shielding portions so that harmful light does not hit the switching elements and the driving circuit of the driving substrate when the counter substrate 200 of the liquid crystal panel is incorporated in the liquid crystal panel. It is arranged at a portion facing the switching element and the drive circuit. The light incident from the substrate 1 side is focused by passing through a portion of the light shielding film pattern 6 where the light shielding film is not formed under the action of the microlens, and then passes through each pixel portion of the liquid crystal panel. The light is emitted from the drive substrate side.
[0034]
Such a counter substrate 200 is manufactured as follows. First, a light-shielding film layer is formed on the cover member 5 of the microlens-equipped substrate 100, and a matrix pattern is formed on this layer by photolithography. That is, a resist film is formed on the light shielding film layer, exposed to light and developed to form a resist pattern, and the light shielding film pattern 6 is formed by etching using the resist pattern as a mask. Next, the remaining resist is removed, and a layer of the transparent electrode 7 as a counter electrode is formed on the light shielding film pattern 6 by a vapor phase growth method or the like.
[0035]
The material constituting the light shielding film pattern 6 may be any material that can shield the light to be used. For example, Cr, Al, or an alloy thereof is used. The light shielding film constituting the light shielding film pattern 6 may be composed of a plurality of layers. Further, as a material constituting the transparent electrode 7, a transparent conductive film such as a so-called ITO film is used. The light shielding film pattern 6 as a black matrix is not necessarily provided.
[0036]
FIG. 5 is an explanatory view of the method for manufacturing the liquid crystal panel according to the embodiment of the present invention. As shown in FIG. 5, the liquid crystal panel 300 basically holds the liquid crystal layer 30 through an alignment film (not shown) between the drive substrate 400 arranged to face the above-described counter substrate 200. Is. The drive substrate 400 includes pixel electrodes 42 provided in a matrix on a transparent substrate 41 such as glass, and switching elements 43 provided corresponding to the pixel electrodes 42.
[0037]
The liquid crystal panel 300 controls the alignment state of the liquid crystal layer 30 by a voltage applied between the transparent electrode 7 of the counter substrate 200 and the pixel electrode 42 of the drive substrate 400, and the light incident from the counter substrate 200 side is controlled. An image is formed by controlling the transmission state.
[0038]
The pixel electrode 42 is made of the same transparent conductive film as the material of the transparent electrode 7 of the counter substrate 200. The switching element 43 is configured by a TFT (Thin Film Transistor) or the like. The switching element 43 forms an image by changing the voltage applied to the pixel electrode 42 in accordance with the received image signal, thereby changing the light transmission state of the liquid crystal layer 30 according to the image signal. It is.
[0039]
That is, as described above, the light incident from the substrate 1 side of the counter substrate 200 is subjected to the converging action of the microlens 10 and passes through the portion where the light shielding film is not formed in the light shielding film pattern 6. Pass through. At that time, the transmission state is controlled by the liquid crystal layer 30, and further passes through the pixel electrode 42 and exits from the driving substrate 300 side so as not to hit the switching element 43 due to the convergence action of the microlens 10. .
[0040]
As shown in FIG. 5, a dustproof substrate 24 may be bonded to the surface of the counter substrate 200 on the light incident side of the substrate 1, and an antireflection film 24 a may be provided on the surface of the dustproof substrate 24. . Further, the dust-proof substrate 44 may be bonded to the surface of the drive substrate 400 on the light emitting side of the substrate 41, and an anti-reflection film 44 a may be provided on the surface of the dust-proof substrate 44. By providing the dustproof substrates 24 and 44, image quality deterioration due to the adhesion of dust can be prevented, and a heat dissipation effect can be obtained. Further, by providing an antireflection film, light loss due to surface reflection can be reduced. The antireflection film is formed directly on the surfaces of the substrates 1 and 31 when the dustproof substrates 24 and 44 are not provided.
[0041]
In such a liquid crystal panel 300, after manufacturing the counter substrate 300 and the drive substrate 400, these substrates are positioned to face each other with a predetermined gap while being positioned via a spacer or a seal member, and a liquid crystal is interposed therebetween. Manufactured by pouring and sealing.
[0042]
FIG. 6 is a cross-sectional view of a modified example of a substrate with microlenses manufactured by the method for manufacturing a substrate with microlenses according to an embodiment of the present invention, and FIG. 7 is a liquid crystal manufactured using the substrate with microlenses shown in FIG. It is sectional drawing of the opposing board | substrate of a panel. The difference between the microlens-equipped substrate 100 and the counter substrate 200 of the liquid crystal panel according to this variation is different from the microlens-equipped substrate 100 and the counter substrate 200 of the liquid crystal panel according to the above-described embodiment. This is the point on the opposite side of the substrate 1. Along with this, the resin 4 is formed, the cover member 5 is attached, and the like on the opposite side of the above-described embodiment. The other points are the same as those of the above-described embodiment, and the manufacturing process thereof is almost the same, so that the description thereof is omitted.
[0043]
In the above-described embodiment, an example in which (c) the first etching step, (d) the second etching opening forming step, and (e) the second etching step is shown. However, the present invention is not limited to this, and the wet etching step is repeated three or more times, such as providing a third etching opening forming step and a third etching step after the second etching step. A concave shape having a plurality of curved surfaces concentrically on the outer peripheral portion may be obtained. Further, alignment marks for forming other patterns may be formed on the substrate or the like at the same time when forming a resist pattern, forming a light shielding film pattern, or forming a recess. Moreover, the medium filled in the recess is not limited to resin, and may be oil or gas whose refractive index is adjusted as long as the refractive index is different from that of the substrate material.
[0044]
In addition, although an example in which a plurality of microlenses 10 are provided has been described, it is needless to say that the present invention can be applied to a case in which only one microlens is provided. Moreover, this microlens-equipped substrate can be used for other uses such as coupling of optical array devices such as an LD array, inter-fiber connection, optical calculation processing, and the like other than the liquid crystal panel.
[0045]
(Example)
Hereinafter, actual manufacturing examples of the substrate with microlenses and the counter substrate of the liquid crystal panel according to the above-described embodiment will be described. As the material of the substrate 1, a material obtained by precisely polishing both surfaces of a synthetic quartz substrate having a length of 127 mm and a width of 127 mm and a thickness of 1.1 mm was used. The refractive index n of this substrate with respect to light having a wavelength of 587.6 nm is 1.458. In addition, the resist film in the photolithography method is a positive type resist having a thickness of 5000 angstroms.
[0046]
(A) Formation of mask layer and resist layer
A synthetic quartz substrate having a length of 127 mm and a width of 127 mm and a thickness of 1.1 mm was prepared. A mask layer 2 was formed by depositing a chromium film having a thickness of 1000 angstroms on the substrate 1 by sputtering or the like. Next, a positive resist film having a thickness of 5000 angstroms was formed thereon to form a resist layer 3.
[0047]
(B) First etching opening formation
The resist layer 3 was exposed to a pattern for forming a first etching opening, and developed to form a resist pattern 3a having a large number of openings 20 in a plan view. Next, the mask layer 2 was etched using the resist pattern 3a as a mask to form a mask pattern 2a. The etching method was performed by bringing the substrate surface into contact with an etching solution. As an etchant, an aqueous solution containing ceric ammonium nitrate and perchloric acid was used.
[0048]
In this way, a pattern having 1028 × 772 matrix-like openings, in which the diameter of the openings was 2.7 μm and the distance (pitch) between the centers of adjacent openings 20 was 14 μm, was formed. At the same time, an alignment mark pattern is formed in a region outside the opening pattern formation region, and this alignment mark is a protective resin. so Covered. Note that the resist pattern 3a was left without being removed.
[0049]
(C) First etching
Next, the substrate 1 was wet-etched using the resist pattern 3a and the mask pattern 2a as a mask. That is, the etching solution was brought into contact with the surface of the substrate 1 exposed from the opening of the pattern, so that a substantially hemispherical first recess 11 was formed on the surface of the substrate 1. As the etching solution, an aqueous solution having a hydrofluoric acid concentration of 5% was used. The etching conditions were a temperature of 40 ° C. and an etching time of 50 to 300 seconds. As a result, a first recess 11 having a depth of 2 μm, an opening radius of 3.4 μm on the substrate surface, and a curvature radius of 3.9 μm in the region where the curved surface was formed was formed.
[0050]
(D) Formation of second etching opening
Next, an aqueous solution containing ceric ammonium nitrate and perchloric acid was used as an etchant to widen the opening of the mask pattern 2a to form a second etching opening 21. The etching conditions were a room temperature, an etching time of 360 sec, and a spin process in which an etching solution was sprayed onto the surface of the substrate 1 while rotating the substrate 1. As a result, a second etching opening 21 having a diameter of 8.85 to 10.85 μm was formed. As a result, the substrate surface that has not yet been etched around the recess 11 is exposed from the opening end by about 1 to 2 μm.
[0051]
(E) Second etching
Next, the substrate 1 is wet etched with the same etching solution as the first etching. The etching conditions were a temperature of 40 ° C. and an etching time of 500 to 700 seconds. Accordingly, the depth of the concave portion is 7.5 μm, the opening radius on the substrate surface is 3.75 μm, the radius of curvature of the first curved surface 12a at the central portion of the concave portion is 3.9 μm, and the curvature of the second curved surface 12b at the outer peripheral portion of the substrate. A second recess 12 having a radius of 7.1 μm was formed. The depth of the second curved surface 12 b was 2 μm from the surface of the substrate 1.
[0052]
(F) Residual layer removal and lens formation
Next, the resist pattern 3a was removed with an alkaline aqueous solution, and the mask pattern 2a was removed with an aqueous solution containing ceric ammonium nitrate and perchloric acid. Thus, a substrate on which a large number of second concave portions 12 having a lens shape were formed was obtained.
[0053]
Next, the recess 12 of the substrate 1 was filled with resin, the resin layer 4 was formed, and the cover member 5 was joined. The resin used was an ultraviolet curable resin having a refractive index of 1.59 with respect to light having a wavelength of 587.5 nm. The resin layer 4 was formed by dropping a resin on the surface of the substrate 1 so that no bubbles were generated in the layer. As the cover member 5, a synthetic quartz glass plate having a thickness of 30 μm was used. The resin layer 4 and the cover member 5 are joined by pressing the cover member 5 against the resin layer 4 so that the thickness of the resin layer 4 between the cover member and the substrate 1 is about 10 μm. It was performed by irradiating with ultraviolet rays and curing. And the outer surface of the cover member 5 and the outer surface of the board | substrate 1 were precision-polished, and the board | substrate 100 with a microlens was obtained.
[0054]
Next, a thin film having a thickness of 30 nm made of an AlTi alloy containing 0.5% Ti is formed on the surface of the cover member 5 of the substrate with microlenses 100 by sputtering, and an oxidation film having a thickness of 80 nm is formed thereon. A chromium thin film was formed. Further, a photosensitive resist film having a thickness of 500 nm was formed thereon by a spin coating method. Next, this resist film was subjected to matrix pattern exposure with a width of 3 to 5 μm and a pitch of 14 μm and developed to form a matrix resist pattern. In this exposure, an alignment mark provided on the outer periphery of the substrate 1 was used as a position reference.
[0055]
Next, after etching the chromium oxide film with a ferric chloride solution using the resist pattern as a mask, the AlTi alloy film is etched with a mixed solution of phosphoric acid and nitric acid, and then the remaining resist pattern is converted into an alkaline aqueous solution. The light-shielding film 6 having a matrix pattern was formed by dissolution and removal. The position of the light shielding film 6 is a position corresponding to the position between the μ lenses 10. Then, an ITO film having a thickness of 150 nm was formed by sputtering on the surface of the light shielding film 6 and the surface of the substrate 1 where the light shielding film 6 was not formed. Note that the substrate 1 was heated to 150 ° C. during the film formation. Thereby, the counter substrate 200 of the liquid crystal panel was obtained.
[0056]
(Comparative Example 1)
After the (b) first etching opening forming step in the above-described embodiment, (c) etching corresponding to the first etching step (however, the etching time is set to about 800 sec) is performed, and the depth is about 7 μm. Then, a hemispherical concave portion having an opening radius of about 8.4 μm and a curvature radius of about 8.5 μm was formed, and then (f) the remaining layer removal and lens formation steps were performed to obtain a substrate with microlenses of Comparative Example 1. . Then, a light-shielding film and a transparent electrode were formed on the substrate with microlenses in the same manner as in the above-described example to obtain a counter substrate of the liquid crystal panel of Comparative Example 1.
[0057]
(Comparative Example 2)
A microlens-equipped substrate and a counter substrate of a liquid crystal panel of Comparative Example 2 were obtained in the same manner as in the above-described example except that the etching corresponding to the first etching in the above-described example was performed by dry etching.
[0058]
The substrate side on which the microlens is formed with respect to each of the microlens-equipped substrate and the counter substrate of the liquid crystal panel according to the above-described embodiment, and the microlens-equipped substrate and the counter substrate of the liquid crystal panel of Comparative Examples 1 and 2. A predetermined light was incident on the light source, and the luminance of the light emitted from the opposite side was measured. On the other hand, except that no microlens is provided, a counter substrate of a liquid crystal panel having the same configuration as the above-described examples and comparative examples is manufactured as a reference counter substrate, and light is incident from one side under the same conditions. The brightness of light emitted from the opposite side was measured.
[0059]
As a result, when the measured luminance of the reference counter substrate was 100%, the measured luminance of the microlens-equipped substrate and the counter substrate of the liquid crystal panel according to the above-described example was 175%. In contrast, the measured luminance of the counter substrate of the liquid crystal panel of Comparative Example 1 was 155%, and the measured luminance of the counter substrate of the liquid crystal panel of Comparative Example 2 was 173%. That is, from the viewpoint of light utilization efficiency, the substrate with microlenses and the counter substrate of the liquid crystal panel according to the above-described example are significantly superior to those of Comparative Example 1 (the microlens is a simple spherical lens). In addition, it was found that the microlens is equal to or greater than that of Comparative Example 2 (the microlens is of an aspherical lens as in the example).
[0060]
Moreover, when the size and shape of each microlens of the substrate with microlenses of the example and the comparative example were observed with a microscope, the microlens of the substrate with the microlens of the example was compared with Comparative Example 2 (the microlens was an example of the microlens). It was confirmed that both the size and the shape were remarkably uniform as compared with the microlens of the aspherical lens similarly to the above. The uniformity of the size and shape of the microlenses causes display unevenness when the projection type liquid crystal projector is formed using the counter substrate. Therefore, when a counter-type substrate using the microlens-equipped substrate of the embodiment is used as a projection type liquid crystal projector, a good liquid crystal projector without display unevenness can be obtained.
[0061]
From the above results, the microlens-equipped substrate and the counter substrate of the liquid crystal panel according to the example of the present invention are the same as those of the liquid crystal panel of Comparative Example 2 in which concave portions are formed using conventional dry etching in terms of light utilization efficiency. Although it is not so different from the counter substrate, it can be seen that the microlens is remarkably superior in terms of size and shape uniformity. In addition, since high-cost and expensive dry etching is not used, high-quality products can be manufactured at low cost.
[0062]
Therefore, when the microlens-equipped substrate and the counter substrate of the liquid crystal panel according to the embodiment of the present invention are used for the liquid crystal panel, an image with a good contrast ratio can be obtained. That is, if a projection type liquid crystal projector is constituted by a liquid crystal panel using a substrate with a microlens and a counter substrate of the liquid crystal panel according to an embodiment of the present invention, a projection type liquid crystal projector with high brightness can be obtained.
【The invention's effect】
As described above, according to the present invention, a microlens-equipped substrate having a microlens having a shape capable of reducing aberration at the outer peripheral portion and having high light utilization efficiency, and a liquid crystal using the microlens-equipped substrate The counter substrate of the panel and the liquid crystal panel can be stably manufactured without using a dry etching process, at a low manufacturing cost, and without product variations.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram of a manufacturing method of a substrate with a microlens according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view of a substrate with a microlens manufactured by the method for manufacturing a substrate with a microlens according to an embodiment of the present invention.
FIG. 3 is a plan view of the substrate with microlenses manufactured by the method for manufacturing the substrate with microlenses according to the embodiment of the present invention.
FIG. 4 is an explanatory diagram of a manufacturing method of the counter substrate of the liquid crystal panel according to the embodiment of the present invention.
FIG. 5 is an explanatory diagram of the manufacturing method of the liquid crystal panel according to the embodiment of the present invention.
FIG. 6 is a cross-sectional view of a modified example of a substrate with microlenses manufactured by the method for manufacturing a substrate with microlenses according to an embodiment of the present invention.
7 is a cross-sectional view of a counter substrate of a liquid crystal panel manufactured using the substrate with a microlens shown in FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Substrate, 2 ... Mask layer, 3 ... Resist layer, 4 ... Resin layer, 5 ... Cover member, 6 ... Light-shielding film, 7 ... Transparent electrode, 100 ... Substrate with microlens, 200 ... Counter substrate of liquid crystal panel, 300 ... Liquid crystal panel, 400 ... Drive substrate.

Claims (3)

A concave portion forming step of forming a large number of concave portions having a lens shape on the translucent substrate; and a microlens forming step of forming a microlens portion by filling the concave portion with a medium having a refractive index different from that of the substrate. A method of manufacturing a substrate with a microlens,
The concave forming step includes
A mask layer and a resist layer forming step of forming a mask layer on the transparent substrate and a resist layer on the mask layer;
A first etching opening forming step in which an opening pattern is exposed to the resist layer, developed, an opening pattern is formed, and an opening is formed in the mask layer using the resist layer as a mask;
,
A first etching step in which an etchant is brought into contact with the surface of the light-transmitting substrate exposed by the first etching opening forming step, and the light-transmitting substrate is etched to form a first recess;
An etching solution that erodes only the mask layer without eroding the resist layer and the translucent substrate is formed in the opening formed in the mask layer in the first etching opening forming step.
An opening of the mask layer is enlarged by bringing it into contact with a side surface, and an unetched substrate surface is exposed around the first recess to form an opening for a second etching to be performed next. A second etching opening forming step,
The translucent substrate is etched by bringing an etchant into contact with the surface of the translucent substrate exposed by the second etching opening forming step and the inner surface of the recess formed by the first etching. A second etching step for forming a second recess having a surface composed of a plurality of different curved surfaces;
A method for producing a substrate with a microlens, comprising: Light which is formed by converging light by the action of the microlens when parallel light is incident from one surface side of the substrate with microlens manufactured by the method for manufacturing a substrate with microlens according to claim 1. A method for producing a counter substrate of a liquid crystal panel, comprising a step of providing a transparent electrode layer on the other surface side of the substrate with microlenses at a position on an optical path of a beam. A counter substrate of a liquid crystal panel manufactured by the method for manufacturing a counter substrate of a liquid crystal panel according to claim 2 ,
Pixel electrodes provided in a matrix on a light-transmitting substrate so as to correspond to the microlenses and transparent electrode layer of the counter substrate of the liquid crystal panel, and switching elements provided corresponding to the respective pixel electrodes A drive board having
The position of the microlens and the transparent electrode layer of the counter substrate of the liquid crystal panel and the position of the pixel electrode and the switching element of the drive substrate are in a predetermined positional relationship, and the counter substrate and the drive substrate of the liquid crystal panel Are arranged opposite each other with a predetermined gap,
A liquid crystal panel manufacturing method, wherein a liquid crystal layer is held and fixed between a counter substrate and a driving substrate of the liquid crystal panel.

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