JP4385899B2 - MICRO LENS ARRAY PLATE, MANUFACTURING METHOD THEREOF, ELECTRO-OPTICAL DEVICE, AND ELECTRONIC DEVICE - Google Patents

Description

  The present invention relates to a technical field of a manufacturing method of a microlens array plate that is preferably used in an electro-optical device such as a liquid crystal device. The present invention further relates to a technical field of a microlens array plate manufactured by the manufacturing method, an electro-optical device including the microlens array plate, and an electronic apparatus including the electro-optical device.

  In an electro-optical device such as a liquid crystal device, various wiring elements such as data lines, scanning lines, and capacitance lines, and various electronic elements such as thin film transistors (hereinafter referred to as TFT (Thin Film Transistor) as appropriate) are included in the image display area. Built. For this reason, when parallel light is incident on the electro-optical device, only the amount of light corresponding to the aperture ratio of each pixel can be used as it is.

  Therefore, conventionally, a microlens array including a microlens corresponding to each pixel is formed on the counter substrate, or a microlens array plate is attached to the counter substrate. With such a microlens, the light that travels toward the non-opening area excluding the opening area in each pixel as it is is condensed in units of pixels and transmitted through the electro-optic material layer. It is guided in the opening area. As a result, bright display is possible in the electro-optical device.

  For this type of microlens, it is important to improve the lens efficiency as a basic requirement. Therefore, aspherical microlenses have been proposed. However, in the manufacture of an aspheric lens, it is technically very difficult to control the lens shape itself. For example, Patent Documents 1 and 2 disclose an aspheric lens in which a first film having an etching rate higher than that of a substrate is formed on a substrate, and a lens surface is formed by etching using a difference in etching rate between the substrate and the first film. A manufacturing method is disclosed.

JP 2004-70282 A JP 2004-70283 A

  However, in such a manufacturing method, even if a lens can be formed in an aspherical shape, the peripheral shape of the lens may vary. In particular, among the microlenses constituting the microlens array, the boundary portion of four microlenses that are diagonally adjacent (that is, near the lens pitch diagonal of 100%) protrudes in a wedge shape, but the tip thereof is May be formed as missing. A feature of the aspherical lens is high light collecting ability due to the curvature of the peripheral edge. However, when the shape of the peripheral edge varies in this way, there is a problem in that the lens efficiency is reduced and variations occur.

  The present invention has been made in view of the above problems, and includes a manufacturing method of a microlens array plate capable of manufacturing an aspherical microlens into a uniform shape, the microlens array plate, and the microlens array plate. Another object is to provide an electro-optical device and an electronic apparatus including the electro-optical device.

  In order to solve the above problems, a method of manufacturing a microlens array plate according to the present invention includes a step of forming a first film having a higher etching rate with respect to a predetermined type of etchant on the substrate than the substrate, and on the first film. And forming a second film having a lower etching rate than the first film, and a mask having an opening on the second film at a position corresponding to the lens center of each of the plurality of microlenses to be formed. Forming a wedge shape that protrudes in the normal direction of the substrate at the boundary of the adjacent microlenses among the plurality of microlenses by performing wet etching with the etchant through the mask and the forming step. A plurality of concaves defining a lens curved surface of each of the plurality of microlenses is formed in the laminate including the second film, the first film, and the substrate. And a step to dig.

  According to the method for manufacturing a microlens of the present invention, first, on a substrate such as a quartz substrate or a glass substrate, a first film having an etching rate higher than that of a predetermined type of etchant such as hydrofluoric acid is formed. . Next, a second film having an etching rate lower than that of the first film is formed on the first film. Here, the first film and the second film are provided on the substrate in order to control the peripheral shape of the microlens formed as a concave portion described later and the entire aspherical shape, respectively. These first and second films are formed by, for example, CVD (Chemical Vapor Deposition), sputtering, or the like.

  Next, a mask having a hole formed at a location corresponding to the center of each of the plurality of microlenses to be formed is formed on the second film. For example, the mask may be directly formed in a region excluding holes on the second film.

  Next, wet etching reaching the substrate is performed on the substrate on which the first and second films are formed through such a mask. The etching rate for the etchant used here is higher in the first film than in the substrate. Therefore, the concave part with the tapered side edge is dug into a wide and shallow shape. At that time, with the progress of etching, adjacent ones of the plurality of recessed portions to be dug are adjacent to each other, and the boundary forms a wedge shape protruding in the normal direction of the substrate. For example, when a plurality of recesses are formed in a matrix, the four closest recesses intersect with each other in the respective diagonal directions to form a wedge-shaped boundary portion. That is, here, the recesses are “close to each other” means that the recesses meet each other and share a boundary.

  The etching rate for the etchant used here is lower in the second film than in the first film. Therefore, the concave portion is formed in a substantially uniform shape with little or no defect in practice, particularly in the peripheral edge portion in the diagonal direction. At this time, the second film may remain on the diagonal peripheral portion of the recess, or the second film may be completely removed by etching.

  In this way, by changing the specific values of the etching rate in each of the substrate, the first film and the second film and the difference in these etching rates, an aspherical lens having various curvatures or various curved surfaces can be obtained. Can be manufactured. The setting of the actual etching rate and the setting of the aperture diameter may be determined individually and specifically according to the desired aspherical surface, experimentally, empirically, mathematically, theoretically, or by simulation.

  Here, the magnitude relationship between the etching rates is specified, but the type of etchant is not specified. Therefore, a plurality of etchants can be used, such as etching the second film, the first film, and the substrate with different etchants. However, using the same type of etchant consistently has the advantage that the etching rate can be easily set and the production efficiency is increased.

  Thereafter, an aspherical microlens array can be manufactured relatively easily by using the curved surface defined by the recess. Specifically, the substrate may be a transparent substrate and the concave medium may be filled with the transparent medium. Or it can also manufacture using a recessed part for a type | mold. Furthermore, a microlens array plate of a biconvex lens can be manufactured by preparing two substrates on which such a microlens array is formed and bonding them together.

  As a result, according to the method for manufacturing a microlens array plate of the present invention, an aspherical microlens can be manufactured relatively easily, and the shape of a plurality of manufactured microlenses can be made uniform. is there. The microlens array plate manufactured in this way can be suitably used for, for example, an electro-optical device in which pixels are arranged in an array or a matrix, and the display luminance for each pixel can be made uniform.

  In one aspect of the method for manufacturing a microlens array plate of the present invention, the etching rate for the etchant of the first film, the substrate, and the second film decreases in this order.

  According to this aspect, the etching rate (R1, Rs, R2) of the first film, the substrate, and the second film is the highest, and the etching rate decreases in the order of the substrate and the second film. (R1> Rs> R2). That is, the second film has an etching rate lower than that of the substrate.

  Thus, by setting the etching rate of the second film sufficiently low, a recess having an aspherical shape as a whole and having a sufficiently reduced defect in the peripheral portion can be obtained.

  In another aspect of the method for manufacturing a microlens array plate of the present invention, the mask is formed in close contact with the second film.

  According to this aspect, since the mask and the second film are in close contact with each other, it is possible to prevent the etchant from penetrating into the interface during etching and to more reliably control the progress of the etching of the second film. it can. This contributes to making the shape of the peripheral portion of the recess uniform.

  Here, “adherent” refers not to a state of being simply in contact but to a state of being joined by a force acting between them. This adhesion force is various interactions acting between the constituent atoms or molecules of the second film and the constituent atoms or molecules of the mask, and at least the etchant permeates the interface between the second film and the mask. It works to the extent that it can be prevented.

  In another aspect of the method for manufacturing a microlens array plate of the present invention, the second film is formed thin enough to disregard the shape variation of the concave portion corresponding to the second film.

  According to this aspect, the second film that defines the shape of the peripheral portion of the recess is formed thin. Therefore, even if the shape variation occurs in the portion corresponding to the second film (that is, the peripheral portion) in the recess, the variation can be ignored with respect to the size of the entire recess. Therefore, the shape uniformity in the peripheral part of the microlens can be ensured.

  In addition, you may set the specific numerical value of the thickness of a 2nd film | membrane suitably according to the size of the micro lens manufactured.

  In this aspect, the thickness of the second film may be set within a range of 3 nm or more and 10 nm or less.

  In this case, the thickness of the second film is set in the range of 3 nm to 10 nm, for example, 5 nm (50 mm). Here, 3 nm is a lower limit value that allows dimensional control, and 10 nm is an upper limit value that allows the thickness of the second film to be relatively ignored with respect to the size of the microlens. For example, the thickness of the first film is set to about 100 nm (1000 mm), which is ten times as large as that of the second film. For this reason, variations in the thickness of the second film in the lens shape can be sufficiently ignored.

  In another aspect of the method for producing a microlens array plate of the present invention, the etching rate is controlled by controlling the film type of the first film or the second film, the forming method, the forming conditions, and the temperature of the heat treatment performed after the forming. Of these, it is performed by setting conditions related to at least one of them.

  According to this aspect, in the first film or the second film, for example, the type of material, density, porosity and the like, for example, a formation method such as CVD, sputtering, etc., the formation temperature such as about 400 ° C. or less or about 400 to 1000 ° C. And the etching rate is controlled by setting conditions according to at least one of the temperatures of the heat treatment performed after the formation of the first film or the second film. By controlling the etching rate, the curvature or curvature distribution on the aspherical surface defined by the finally obtained recess, or the peripheral shape of the recess can be controlled relatively easily. The curvature or curvature distribution on the aspheric surface defined by the finally obtained recess or the peripheral shape of the recess can also be controlled by the film thickness of the first film or the second film.

  In another aspect of the method for producing a microlens array plate of the present invention, the substrate is made of a transparent substrate, and further includes a step of filling the plurality of recesses with a transparent medium having a higher refractive index than the transparent substrate. Yes.

  According to this aspect, since a transparent medium having a higher refractive index is placed in a plurality of concave portions dug in a substrate made of a transparent substrate, a plurality of microlenses can be manufactured as aspherical convex lenses on the transparent substrate. It becomes. At this time, the transparent medium is made of a transparent resin or the like and may also serve as an adhesive. For example, you may serve as the adhesive agent at the time of bonding a cover glass to a transparent substrate.

  An example of the transparent substrate is quartz. In this case, when the first film or the second film is formed, the substrate is not destroyed even if it is exposed to a high temperature. However, when the first film or the second film is formed at a low temperature, the transparent substrate is not required to have heat resistance. For example, a glass plate, a plastic or a resin plate may be used. In any case, there is no problem as long as the transparent substrate is a material that can be etched with a predetermined type of etchant together with the first film or the second film.

  In addition, when using the recessed part dug in the board | substrate as a type | mold of a microlens, a board | substrate does not need to be transparent.

  In order to solve the above problems, the microlens array plate of the present invention includes a substrate, a first film having an etching rate higher than that of the substrate, and a second film having an etching rate lower than that of the first film. Each of the curved surfaces of the laminated body is defined by a plurality of concave portions that are dug so as to form a wedge shape protruding in the normal direction of the substrate at the boundary between adjacent microlenses. A plurality of microlenses are formed.

  According to the microlens array plate of the present invention, since it can be manufactured by the above-described manufacturing method of the microlens array plate of the present invention, it is possible to efficiently collect light source light, outside light, etc. A relatively easy and stable quality microlens array plate can be realized.

  In the manufacturing process of the microlens array, when the recess is formed, the first film or the second film may remain on the peripheral portion or the side surface portion of the recess. Since these are located at the edge of the optical path of the light collected by the microlens, even if the first film and the second film are formed from a semi-transparent film or an opaque film, they affect the optical performance of the microlens. Adverse effects are limited.

  In order to solve the above problems, an electro-optical device of the present invention includes the above-described microlens array plate of the present invention, a plurality of display electrodes opposed to each of the plurality of microlenses, and the plurality of display electrodes. Wirings or electronic elements connected to each other.

  According to the electro-optical device of the present invention, since the microlens array plate of the present invention described above is provided, a plurality of aspherical microlenses can efficiently collect light source light, external light, etc. for each pixel, An electro-optical device capable of displaying a bright and clear image can be realized. At the same time, since these aspherical microlenses are formed in a uniform shape, light can be emitted uniformly in the aperture region of each pixel, and an electro-optical device with good display quality can be realized.

  Note that such an electro-optical device is an active matrix driving type liquid crystal in which scanning electrodes, data lines, and other electronic elements such as TFTs are connected to display electrodes such as island-shaped pixel electrodes or stripe-shaped electrodes. It is constructed as an electro-optical device such as a device.

  In order to solve the above problems, an electronic apparatus according to the present invention includes the above-described electro-optical device according to the present invention.

  According to the electronic apparatus of the present invention, since it is configured to include the above-described electro-optical device of the present invention, a projector, a liquid crystal television, a mobile phone, an electronic notebook, a word processor, which is bright and maintains excellent display quality, Various electronic devices such as a viewfinder type or a monitor direct-view type video tape recorder, a workstation, a videophone, a POS terminal, and a touch panel can be realized.

  Such an operation and other advantages of the present invention will become apparent from the embodiments described below.

  Embodiments of the present invention will be described below with reference to the drawings.

(Micro lens array plate)
First, the microlens plate according to the present embodiment will be described with reference to FIGS. FIG. 1 shows a schematic configuration of a microlens array plate according to the present embodiment. FIG. 2 is an enlarged view of a portion related to four microlenses. FIG. 3 is an enlarged view of a partial cross section of the microlens array plate of the present embodiment, and FIG. 4 is an enlarged view of a boundary portion constituted by four closest microlenses. FIG. 5 shows a modification of the microlens array plate of the present embodiment.

  As shown in FIG. 1, the microlens array plate 20 of this embodiment includes a transparent plate member 210 made of, for example, a quartz plate and covered with a cover glass 200. In the transparent plate member 210, a large number of concave depressions are dug in a matrix. And, in this concave recess, the cover glass 200 and the transparent plate member 210 are bonded to each other, for example, an adhesive made of a photosensitive resin material is cured, and has a higher refractive index than the transparent plate member 210. A transparent adhesive layer 230 is filled. As a result, a large number of microlenses 500 arranged in a matrix on a plane are constructed.

  As described above, in the present embodiment, an example of the “substrate” according to the present invention is configured from the transparent plate member 210, and an example of the “transparent medium” according to the present invention is configured from the adhesive layer 230.

  As shown in FIGS. 2 and 3, the curved surface of each microlens 500 is defined by a transparent plate member 210 and an adhesive layer 230 having different refractive indexes. Each microlens 500 is constructed as a convex lens that protrudes downward in FIG.

  The lens surface of the microlens 500 includes a peripheral portion 500A and a central portion 500B having different curvatures. The peripheral portion 500A is mainly configured by the first film 221 on the peripheral side of the microlens 500, and the inner central portion 500B is configured by the transparent plate member 210. The first film 221 is made of a material having an etching rate higher than that of the transparent plate member 210, for example, a silicon oxide film such as HTO (High Temperature Oxide). Such an aspherical microlens 500 has a larger radius of curvature near the outer periphery than a spherical lens, and the lens efficiency is improved in accordance with the degree of aspherical surface.

  Further, in the present embodiment, as described later, since it is manufactured by the manufacturing method unique to the present invention, the boundary between the microlenses 500 that are adjacent to each other in the diagonal direction (that is, the position where the lens pitch diagonal is 100%) and its A slight amount of the second film 222 exists at the boundary portion 510 in the vicinity.

  As shown in FIG. 4, the boundary portion 510 is formed in a wedge shape having four ridgelines, with the lens surfaces of the four closest microlenses 500 intersecting each other. And the very tip part is comprised with the 2nd film | membrane 222. FIG. The second film is provided in order to form a uniform shape without losing each of the plurality of boundary portions 510 at the time of manufacture. The second film 222 is made of a material having an etching rate lower than that of the transparent plate member 210, for example, a silicon nitride film or a silicon oxide film formed by high-temperature CVD.

  As will be described later, here, the second film 222 is formed to be extremely thinner than the first film in order to keep the shape variation of the tip portion within the error range. The thickness of the second film 222 is set within a range of 3 nm to 10 nm, for example, 5 nm (50 mm).

  When the microlens array plate 20 is used, each microlens 500 is arranged so as to correspond to each pixel of an electro-optical device such as a liquid crystal device described later. Accordingly, the incident light incident on each microlens 500 is condensed toward the center of each pixel in the electro-optical device by the refraction action of the microlens 500. The angle formed by the tangent to the upper edge of the peripheral edge 500A and the horizontal plane is, for example, 50 to 60 degrees. In that case, compared with the case where the angle is about 30 to 40 degrees, or conversely about 70 to 80 degrees, very good lens efficiency is obtained, and the generation of irregular reflection light and the like is effective. Can be prevented. By appropriately setting this angle in accordance with the specifications of the electro-optical device, incident light condensed through not only the vicinity of the center of each microlens 500 but also the vicinity of the edge of the liquid crystal layer and the like inside the electro-optical device When transmitting, it can pass through the aperture region of the corresponding pixel.

  By such a condensing function of the aspherical microlens 500, the incident light incident from the upper side in FIG. 3 can be used as light that efficiently contributes to display. In addition, since the microlens 500 is manufactured by the manufacturing method of the present invention described later, the shape uniformity of the microlens 500 is extremely high, and the lens efficiency can be made uniform. Therefore, in the electro-optical device using the microlens array plate 20, it is possible to display an image that is bright and clear and has very little luminance unevenness.

Moreover, since the microlens array plate 500 of the present invention having such excellent lens characteristics is manufactured by the manufacturing method of the present invention described later, it is easy to manufacture and stable quality can be obtained.
<Modification>
As shown in FIG. 5, as a modification of the present embodiment, the microlens array plate may be provided with a light shielding film 240 that at least partially defines a non-opening region in the electro-optical device to which the microlens array plate is attached. Good. More specifically, the light shielding film 240 having a grid-like planar pattern may be configured so as to define a grid-like non-opening region independently. Or you may comprise the light shielding film 240 which has a striped planar pattern so that a grid | lattice-like non-opening area | region may be prescribed | regulated in cooperation with another light shielding film.

  If configured as shown in FIG. 5, the non-opening region of each pixel can be more reliably defined, and light leakage between the pixels can be prevented. Furthermore, light is reliably prevented from being incident on an electronic element such as a TFT that is formed in a non-opening region of the electro-optical device and changes its characteristics when a light leaks due to photoelectric effect. It is also possible.

  In FIG. 5, a protective film 241 is formed on the light shielding film 240. Further, instead of or in addition to the protective film 241, a counter electrode and an alignment film as described later may be formed. In addition, an R (red), G (green), or B (blue) color filter is formed in the opening region of each pixel partitioned by the light shielding film 240 with respect to the microlens array plate as shown in FIG. It is also possible.

(Electro-optical device)
Next, the electro-optical device according to this embodiment will be described with reference to FIGS. Here, as an example of the electro-optical device of the present invention, a TFT active matrix driving type liquid crystal device with a built-in driving circuit will be described.

  6 is a plan view of the TFT array substrate together with the components formed thereon, as viewed from the above-described microlens array plate used as a counter substrate, and FIG. 7 is a cross-sectional view taken along line HH ′ of FIG. It is sectional drawing.

  6 and 7, in the electro-optical device according to the present embodiment, a TFT array substrate 10 and a microlens array plate 20 used as a counter substrate are disposed to face each other. A liquid crystal layer 50 is sealed between the TFT array substrate 10 and the microlens array plate 20, and the TFT array substrate 10 and the microlens array plate 20 are provided in a seal region positioned around the image display region 10a. They are bonded to each other by a sealing material 52.

  The sealing material 52 is made of, for example, an ultraviolet curable resin, a thermosetting resin, or the like for bonding the two substrates together. Further, a gap material such as glass fiber or glass bead is dispersed in the sealing material 52 to set the distance between the TFT array substrate 10 and the microlens array plate 20 (inter-substrate gap) to a predetermined value. Such a structure is suitable for a small and enlarged display for a projector light valve. However, if the electro-optical device is a large-sized liquid crystal device that displays an equal magnification, such a gap material may be used for the liquid crystal layer 50. It may be included.

  On the inside of the sealing material 52 on the microlens array plate 20, a light-shielding frame light-shielding film 53 that defines the frame area of the image display region 10a is provided. However, a part or all of such a frame light shielding film may be provided as a built-in light shielding film on the TFT array substrate 10 side.

  A data line driving circuit 101, a scanning line driving circuit 104, and an external circuit connection terminal 102 are provided in the peripheral area of the image display area 10 a on the TFT array substrate 10, and these are connected to each other by a plurality of wirings 105. Has been. In addition, the TFT array substrate 10 includes a sampling circuit that samples an image signal and supplies the data line to a data line, a precharge circuit that supplies a precharge signal having a predetermined voltage level to the data line prior to the image signal, You may form the inspection circuit etc. which test | inspect the quality of the said electro-optical apparatus at the time of shipment, a defect, etc. The microlens array plate 20 is provided with a vertical conduction member 106 that functions as a vertical conduction terminal between the two substrates.

  In FIG. 7, on the TFT array substrate 10, an alignment film is formed on the pixel electrode 9a after the pixel switching TFT, the scanning line, the data line and the like are formed. On the other hand, on the microlens array plate 20, the counter electrode 21 is formed in addition to the cover glass 200, the transparent plate member 210, and the microlens 500 described above, and the uppermost layer portion (under the microlens array plate 20 in FIG. 7). An alignment film is formed on the side surface. Further, the liquid crystal layer 50 is made of, for example, a liquid crystal in which one or several types of nematic liquid crystals are mixed, and takes a predetermined alignment state between the pair of alignment films.

  Next, the circuit configuration and operation of the electro-optical device will be described with reference to FIG. FIG. 8 illustrates an equivalent circuit of various elements, wirings, and the like in a plurality of pixels formed in a matrix that forms an image display area of the electro-optical device.

  In FIG. 8, a pixel electrode 9a and a TFT 30 for switching control of the pixel electrode 9a are formed in a plurality of pixels arranged in a matrix in the image display region 10a. The data line 6 a is electrically connected to the source of the TFT 30. Image signals S1, S2,... Sn are respectively supplied to a plurality of data lines 6a arranged corresponding to the pixel columns. The image signals S1, S2,... Sn may be supplied line-sequentially in this order, or may be supplied for each group to a plurality of adjacent data lines 6a.

  A scanning line 3a is electrically connected to the gate of the TFT 30, and is configured to supply scanning signals G1, G2,... Gm to the scanning line 3a line-sequentially in accordance with horizontal scanning. That is, the TFT 30 opens and closes according to the input timing of the scanning signals G1, G2,. The pixel electrode 9a is electrically connected to the drain of the TFT 30, and by opening and closing the TFT 30 at a predetermined timing, the image signals S1, S2,... Sn supplied from the data line 6a are written, Is held for a certain period of time. The liquid crystal modulates light by changing the orientation and order of the molecular assembly in accordance with the potential level between the pixel electrode 9a and the counter electrode 21, thereby enabling gradation display. Here, in order to prevent the held image signal from leaking, a storage capacitor 70 is added in parallel with the liquid crystal capacitor formed between the pixel electrode 9a and the counter electrode.

  Next, a specific configuration of the image display region 10a of the electro-optical device will be described with reference to FIGS. FIG. 9 shows a planar configuration on the TFT array substrate 10. FIG. 10 is a cross-sectional view taken along line A-A ′ of FIG. 9. In FIG. 9, the scales are different for each layer and each member so that each layer and each member have a size that can be recognized on the drawing.

  In FIG. 9, pixel electrodes 9 a (outlined by dotted line portions 9 a ′) are provided in the opening regions of the respective pixels arranged in a matrix in the X direction and the Y direction. The non-opening region of the pixel is defined by wiring extending along the vertical and horizontal boundaries of the pixel electrode 9a, such as the data line 6a, the scanning line 3a, and the capacitor line 300. In addition, the scanning line 3a is arranged so as to face the channel region 1a 'in the semiconductor layer 1a, and the scanning line 3a functions as a gate electrode. As described above, the pixel switching TFT 30 is provided at each of the intersections between the scanning line 3a and the data line 6a.

  9 and 10, each circuit element of the pixel portion described above is patterned and stacked as a conductive film on the TFT array substrate 10. Each circuit element includes, in order from the bottom, the first layer including the lower light-shielding film 11a, the second layer including the gate electrode 3a, the third layer including the storage capacitor 70, the fourth layer including the data line 6a, and the like. It consists of a fifth layer including the electrode 9a and the like. Further, the base insulating film 12 is provided between the first layer and the second layer, the first interlayer insulating film 41 is provided between the second layer and the third layer, the second interlayer insulating film 42 is provided between the third layer and the fourth layer, and the fourth layer. A third interlayer insulating film 43 is provided between each of the layers and the fifth layers to prevent the above-described elements from being short-circuited.

  The TFT array substrate 10 is made of, for example, a quartz substrate, a glass substrate, or a silicon substrate. On the lower layer side of the TFT 30 on the TFT array substrate 10, a lower light shielding film 11 a is provided in a lattice shape. The lower light-shielding film 11a is made of, for example, a simple metal, an alloy containing at least one of refractory metals such as Ti (titanium), Cr (chromium), W (tungsten), Ta (tantalum), and Mo (molybdenum). It is made of metal silicide, polysilicide, or a laminate of these.

  The TFT 30 has an LDD (Lightly Doped Drain) structure. The TFT 30 has a scanning line 3a, a channel region 1a ′ of the semiconductor layer 1a in which a channel is formed by an electric field from the scanning line 3a, the scanning line 3a and the semiconductor layer 1a. Insulating film 2 including a gate insulating film that insulates, low concentration source region 1b and low concentration drain region 1c of semiconductor layer 1a, high concentration source region 1d and high concentration drain region 1e of semiconductor layer 1a. The high concentration source region 1 d is connected to the data line 6 a through the contact hole 81, and the high concentration drain region 1 e is connected to the relay layer 71 of the storage capacitor 70 through the contact hole 83.

  A storage capacitor 70 is provided above the TFT 30. The storage capacitor 70 includes a relay layer 71 as a pixel potential side capacitor electrode connected to the high concentration drain region 1e of the TFT 30 and the pixel electrode 9a and a part of the capacitor line 300 as a fixed potential side capacitor electrode. It is formed by being opposed to each other through the film 75. The capacitor line 300 is electrically connected to a constant potential source to have a fixed potential. The capacitor line 300 is formed in a stripe shape along the scanning line 3a in plan view, and protrudes up and down in FIG. Such a capacitor line 300 is made of a light-shielding conductive film containing metal, for example, and has a function as a light-shielding film that shields the TFT 30 from incident light on the upper side of the TFT 30 in addition to a function as a fixed potential side capacitor electrode. In FIG. 9, the lower light-shielding film 11 a formed in a lattice shape, and the lattice-shaped light-shielding film formed by intersecting the data lines 6 a extending in the vertical direction and the capacitor lines 300 extending in the horizontal direction. The opening area of each pixel is defined.

  The data line 6a is electrically connected to the high-concentration source region 1d in the semiconductor layer 1a made of, for example, a polysilicon film via the contact hole 81. Note that a relay layer made of the same film as the relay layer 71 described above may be formed, and the data line 6a and the high-concentration source region 1d may be electrically connected through the relay layer and the two contact holes.

  The pixel electrode 9a is electrically connected to the high-concentration drain region 1e in the semiconductor layer 1a through the contact holes 83 and 85 by relaying the relay layer 71. An alignment film 16 that has been subjected to an alignment process such as a rubbing process is provided on the upper layer side of the pixel electrode 9a. The pixel electrode 9a is made of a transparent conductive film such as an ITO film. The alignment film 16 is made of a transparent organic film such as a polyimide film.

  On the other hand, a counter electrode 21 is provided on the entire surface of the microlens array plate 20, and an alignment film 22 that has been subjected to a predetermined alignment process such as a rubbing process is provided thereon. The counter electrode 21 is made of a transparent conductive film such as an ITO film. The alignment film 22 is made of a transparent organic film such as a polyimide film. As shown in FIG. 5, the microlens array plate 20 may be provided with a light shielding film 240 in a lattice shape or a stripe shape corresponding to the non-opening region of each pixel. The light shielding film 240 also contributes to preventing light incident from the microlens array plate 20 side from entering the channel region 1a '. Then, liquid crystal is sealed between the TFT array substrate 10 and the microlens array plate 20 arranged so that the pixel electrode 9a and the counter electrode 21 face each other, and a liquid crystal layer 50 is formed.

  Here, the light collecting function of the microlens array plate 20 in the electro-optical device will be described with reference to FIG. FIG. 11 shows how incident light is collected by each microlens 500 in the microlens array plate 20. In FIG. 11, each microlens 500 is arranged so that the center of the lens coincides with the center of each pixel.

  In FIG. 11, the microlens array plate 20 is formed at a plurality of microlenses 500 arranged in a matrix shape for condensing incident light incident from above into the aperture region of the pixel and the lens edge thereof. A first film 221. A counter electrode 21 and an alignment film 22 are formed on the transparent plate member 210 (on the lower side in the figure).

  In the electro-optical device having such a configuration, incident light that is incident from the microlens array plate 20 side during driving is condensed by the plurality of microlenses 500 in the corresponding pixel aperture regions. Therefore, the effective aperture ratio in each pixel is increased as compared with the case without the microlens 500.

  In addition, the microlens 500 is excellent in lens efficiency because the shape of the lens surface is defined as an aspheric surface. Particularly, since the use efficiency of incident light at the peripheral portion 500A is extremely high, a display with a good contrast ratio is possible. It is. In addition, since the shape of each microlens 500, in particular, the shape of the boundary portion is substantially uniform, the lens efficiency of each microlens 500 is uniform, and there is no luminance unevenness for each pixel, and a good display is possible. .

  In such an electro-optical device, for example, the TN (Twisted Nematic) mode, VA (Vertically) are respectively provided on the side on which the projection light of the microlens array plate 20 enters and the side on which the emission light of the TFT array substrate 10 exits. Aligned) mode, PDLC (Polymer Dispersed Liquid Crystal) mode, and other modes, and normally white mode / normally black mode, polarizing films, retardation films, polarizing plates, etc. are arranged in a predetermined direction. .

  In this embodiment, the microlens array plate 20 is used as the counter substrate. However, the microlens array plate 20 can be used as a TFT array substrate and a circuit can be constructed thereon.

(Manufacturing method of micro lens array plate)
Next, a method for manufacturing the microlens array plate 20 according to the present embodiment will be described with reference to FIGS. 12 and 13 show the manufacturing process of the microlens array plate 20. FIG. 15 shows a comparative example of the microlens array plate 20, and FIG. 16 shows a modification.

  First, in the process of FIG. 12A, a first film 221a having an etching rate higher than that of the transparent plate member 210a for a predetermined type of etchant such as hydrofluoric acid is formed on the transparent plate member 210a made of quartz or the like. Such a first film 221a is formed as a silicon oxide film by, for example, CVD or sputtering. Thereafter, the first film 221a is subjected to heat treatment or annealing at a predetermined temperature of, for example, about 800 to 900 ° C. to control the etching rate of the first film 221a. At this time, since the transparent plate member 210a is made of, for example, quartz, there is no particular problem that the transparent plate member 210a is broken even if such a relatively high temperature heat treatment is performed. Here, the thickness of the first film 221a is 100 nm (1000 mm).

  Further, a second film 222a having an etching rate lower than that of the transparent plate member 210a is formed on the first film 221a. The second film 222a is formed so as to have good adhesion to a mask layer 612, which will be described later, and to have a low etching rate with respect to the above-described etchant. Accordingly, here, the etching rate for a predetermined etchant increases in the order of the first film 221a, the transparent plate member 210a, and the second film 222a. For example, the material of the second film 222a is not particularly limited. For example, the second film 222a is formed as a silicon nitride film or a silicon oxide film by high-temperature CVD or the like. Here, the thickness of the second film 222a is set within a range of 3 nm to 10 nm, specifically 5 nm (50 mm).

  Next, in the step of FIG. 12B, a mask layer 612 is formed on the first film 221a from a polysilicon film or an amorphous silicon film, for example, by CVD, sputtering, or the like. In the mask layer 612, a hole 612a is formed at a position corresponding to the center of the microlens to be formed by patterning using photolithography and etching. The diameter of the hole 612a is set to be smaller than the diameter of the microlens 500 to be formed.

  Next, in the process of FIG. 12C, the second film 222a, the first film 221a, and the transparent plate member 210a are made to pass through the mask 612 having such holes 612a by an etchant such as hydrofluoric acid. , Wet etching. Then, since the etching rate with respect to the etchant of the first film 221a is higher than that of the transparent plate member 210a, the first film 221a is etched faster. That is, side etching is relatively large, and a concave portion having a taper and a shallow bottom is dug.

  The state of progress of etching at this time will be described step by step with reference to FIG.

  In FIG. 13A, when etching is started, the second film 222a, the first film 221a, and the transparent plate member 210a are dug in order.

  Subsequently, in FIG. 13B and further in FIG. 13C, the etching proceeds in a manner characteristic of the present invention from the magnitude relationship among the etching rates of the second film 222a, the first film 221a, and the transparent plate member 210a. To do. That is, the first film 221a is etched faster than the transparent plate member 210a, thereby forming a tapered surface as shown in the figure. On the other hand, the etching of the second film 222a in contact with the upper surface of the first film 221a is more marked than the first film 221a. Therefore, the etching on the upper surface side does not proceed unnecessarily. The effect of controlling the etching of the second film 222a also contributes to the high adhesion between the second film 222a and the mask 612. As a result, even when the four recesses 250 that are closest to each other come into contact with each other as etching progresses, the boundary portions can be formed without being lost.

  Thereafter, in FIG. 13D, the etching is finished when the recess 250 is dug to a predetermined size. Thus, the transparent plate member 210 in which the concave portion 250 is dug is formed at each of the locations corresponding to the center of the microlens to be formed.

  Here, the surface formed by the recess 250 has a planar sectional shape derived from the tapered shape of the first film 221 in the peripheral portion, whereas the center with the transparent plate member 210 inside the peripheral portion as a base. The part becomes a mortar-shaped curved surface having a shallow bottom due to the difference in the etching rate. That is, the curved surface of the recess 250 constitutes an aspheric surface as a lens surface. Further, according to the progress of the etching at this time, a unique structure of the present invention is obtained in which the first film 221 and the second film 222 are left on the peripheral edge of the recess 250.

  In FIG. 14, in the comparative example in which the second film 222a is not formed, the recess 250 'is formed by the same process as in the present embodiment except for the formation of the second film 222a. The boundary portion 510 ′ of the concave portion 250 ′ is formed by etching the first film 221 ′. For example, a defective portion 512 is generated on a ridge line 511 formed by intersecting the concave portions 250 ′. On the other hand, in the present embodiment, the presence of the second film 222 suppresses the occurrence of defects at the boundary portion 510.

  Note that the final shape of the second film 222 by the etching process (that is, the shape of the tip of the boundary portion 510) may depend on the etching conditions. However, since the second film 222 is formed to be extremely thin as compared with the first film as described above, even if a shape variation occurs in the tip portion, it may remain within the error range. it can.

  As a result, in the present embodiment, it is possible to form the recess 250 in a uniform shape, particularly in the boundary portion 510.

  Also, here, for example, the method of forming the first film 221a and the second film 222a, such as CVD, sputtering, etc., for example, about 400 ° C. or less, such as the material, density, porosity, etc. Alternatively, the condition setting relating to at least one of the formation temperature of the first film 221a and the second film 222a, such as about 400 to 1000 ° C., and the temperature in the heat treatment or annealing after the formation of the first film 221a and the second film 222a. Thus, the etching rate is controlled. For example, in CVD and sputtering, the film quality of the first film 221a or the second film 222a becomes denser, and the etching rate can be increased. Further, for example, with respect to the heat treatment after the formation of the first film 221a or the second film 222a, the film quality becomes denser and the etching rate can be lowered when the temperature is raised, and conversely, the etching rate can be raised when the temperature is lowered. By controlling the etching rate, the curvature or curvature distribution on the aspheric surface defined by the finally obtained recess 250 can be controlled relatively easily. The curvature or curvature distribution on the aspherical surface defined by the finally obtained recess 250 can also be controlled by the film thickness of the first film 221a or the second film 222a.

  The various conditions for etching rate control and the film thickness settings of the first film 221a and the second film 222a are actually used by experimental, empirical, theoretical, or simulation. It may be set individually and specifically according to the size and performance required for the microlens 500, device specifications, and the like.

  Further, in the step of FIG. 12D, a thermosetting transparent adhesive is applied to the surface of the microlens 500, and the cover glass 200 made of neoceram / quartz or the like is pressed and cured. Thereby, the microlens 500 in which the adhesive layer 230 is filled in each concave portion 250 dug in the transparent plate member 210 is completed. At this time, by forming the adhesive layer 230 having a higher refractive index than that of the transparent plate member 210, the aspherical microlenses 500 each formed of a convex lens can be formed relatively easily. In this step, the cover glass 200 may be polished to obtain a cover glass 200 having a desired thickness.

  As described above, according to the manufacturing method of the present embodiment, the microlens array plate 20 in which the aspherical microlenses 500 as shown in FIGS. 1 to 4 are formed in an array is relatively efficient and uniform. Can be manufactured in various shapes.

  Here, the case where the first film 221 and the second film 222 are left in the boundary portion 510 as a structure unique to the present invention has been described, but in such a manufacturing method, depending on the progress of etching, Different forms of recesses can be made. For example, if the degree of progress of etching is deep, as shown in FIG. 15, a recess 260 in which only the first film 221 is left is formed at the boundary portion 520. Such a microlens array plate is also included in the technical scope of the present invention.

  Furthermore, it is also possible to manufacture a microlens of a biconvex lens by preparing two transparent plate members 210 at the stage where the concave portion 250 is completed and bonding them together. Alternatively, an aspherical microlens can be manufactured by using the recess 250 as a mold in the 2P method or the like.

  In addition, in the case of manufacturing the microlens array plate in the modified embodiment shown in FIG. 5, the light shielding film 240, the protective film 241 and the like are formed by sputtering, coating, etc. following the process of FIG. Films may be formed in this order.

  In the above embodiment, the TFT matrix driving type liquid crystal device has been described. However, the electro-optical device of the present invention is a device in which each pixel is driven by a thin film diode (TFD) instead of the TFT. May be.

(Electronics)
Next, as a specific example of an electronic apparatus using the electro-optical device described above in detail as a light valve, an overall configuration, particularly an optical configuration, of an embodiment of a double-plate color projector will be described. FIG. 16 is a schematic cross-sectional view of a multi-plate color projector.

  In FIG. 16, a liquid crystal projector 1100, which is an example of a double-plate type color projector in the present embodiment, prepares three liquid crystal modules including an electro-optical device having a drive circuit mounted on a TFT array substrate, and each of them is an RGB light. It is configured as a projector used as the valves 100R, 100G, and 100B.

  In the liquid crystal projector 1100, when projection light is emitted from a lamp unit 1102 of a white light source such as a metal halide lamp, light components R, G, and R corresponding to the three primary colors of RGB are obtained by three mirrors 1106 and two dichroic mirrors 1108. B is divided into the light valves 100R, 100G and 100B corresponding to the respective colors. At this time, in particular, the B light is guided through a relay lens system 1121 including an incident lens 1122, a relay lens 1123, and an exit lens 1124 in order to prevent light loss due to a long optical path. The light components corresponding to the three primary colors modulated by the light valves 100R, 100G, and 100B are synthesized again by the dichroic prism 1112 and then projected as a color image on the screen 1120 via the projection lens 1114.

  The present invention is not limited to the above-described embodiments, and can be appropriately changed without departing from the spirit or idea of the invention that can be read from the claims and the entire specification, and the manufacture of microlenses with such changes A method, a microlens, an electro-optical device, and an electronic apparatus are also included in the technical scope of the present invention.

1 is a schematic perspective view of an embodiment according to a microlens array plate of the present invention. It is a partial expanded plan view which expands and shows the part which concerns on four microlenses among embodiment which concerns on a microlens array board. It is a partial expanded sectional view of an embodiment concerning a micro lens array board. It is the elements on larger scale which expand and show the boundary part of the micro lens in the embodiment concerning a micro lens array board. It is the elements on larger scale in the deformation | transformation form of the micro lens array board of this invention. It is the top view which looked at the TFT array board | substrate in embodiment which concerns on the electro-optical apparatus of this invention from the opposing board | substrate side with each component formed on it. FIG. 7 is a cross-sectional view taken along the line H-H ′ of FIG. 6. FIG. 3 is a block diagram illustrating an equivalent circuit of various elements, wirings, and the like provided in a plurality of pixels in a matrix that form an image display area in an embodiment related to an electro-optical device. 4 is a plan view of a plurality of pixel groups adjacent to each other on a TFT array substrate on which data lines, scanning lines, pixel electrodes, and the like are formed in an embodiment related to an electro-optical device. FIG. FIG. 10 is a cross-sectional view taken along line A-A ′ of FIG. 9. FIG. 5 is a cross-sectional view schematically illustrating a state in which incident light is collected by each microlens of a microlens array plate used as a counter substrate in the embodiment according to the electro-optical device. It is process drawing which shows the manufacturing method of a micro lens array board. FIG. 13 is a process diagram sequentially illustrating an etching progress process in the process of FIG. It is sectional drawing which shows the comparative example of a micro lens array board. It is sectional drawing which shows the modification of a micro lens array board. 1 is a schematic cross-sectional view showing a color liquid crystal projector as an example of a double-plate color projector that is an embodiment of an electronic apparatus of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... TFT array substrate, 20 ... Microlens array plate, 200 ... Cover glass, 210 ... Transparent plate member, 221 ... First film, 222 ... Second film, 230 ... Adhesive layer, 240 ... Light shielding film, 500 ... Microlens , 500A ... peripheral edge, 500B ... central part, 510 ... boundary part.

Claims (10)

Forming a first film having an etching rate higher than that of the substrate on the substrate with a predetermined type of etchant;
Forming a second film having a lower etching rate than the first film and a thickness thinner than the first film on the first film ;
Forming a mask having an opening on the second film at a location corresponding to the center of each of the plurality of microlenses to be formed;
By performing wet etching with the etchant through the mask, the second film so as to form a wedge shape projecting in the normal direction of the substrate at the boundary between adjacent microlenses among the plurality of microlenses, A method of manufacturing a microlens array plate, comprising: a step of digging a plurality of recesses defining a lens curved surface of each of the plurality of microlenses in a laminate including the first film and the substrate.   2. The method of manufacturing a microlens array plate according to claim 1, wherein the first film, the substrate, and the second film have an etch rate with respect to the etchant that decreases in this order.   The method for manufacturing a microlens array plate according to claim 1, wherein the mask is formed so as to be in close contact with the second film.   4. The microlens array according to claim 1, wherein the second film is formed so thin that a variation in the shape of the concave portion corresponding to the second film is negligible. 5. A manufacturing method of a board.   5. The method of manufacturing a microlens array plate according to claim 4, wherein the thickness of the second film is set in a range of 3 nm or more and 10 nm or less.   The etching rate is controlled by setting conditions relating to at least one of a film type of the first film or the second film, a forming method, forming conditions, and a temperature of heat treatment performed after the forming. The method for producing a microlens array plate according to any one of claims 1 to 5. The substrate is a transparent substrate,
The method for manufacturing a microlens array plate according to any one of claims 1 to 6, further comprising a step of filling the plurality of concave portions with a transparent medium having a refractive index larger than that of the transparent substrate. . A laminate comprising a substrate, a first film having an etching rate higher than that of the substrate, and a second film having a lower etching rate than the first film and a thickness smaller than that of the first film. ,
A plurality of microlenses each having a curved lens surface defined by a plurality of concave portions dug in a wedge shape projecting in the normal direction of the substrate at a boundary between adjacent microlenses is formed on the laminate. A microlens array plate characterized by comprising:   9. The microlens array plate according to claim 8, a plurality of display electrodes facing each of the plurality of microlenses, and a wiring or an electronic element connected to each of the plurality of display electrodes. An electro-optical device.   An electronic apparatus comprising the electro-optical device according to claim 9.

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