JP2005221548A - Manufacturing method of micro lenses and the same, and optoelectronic device and electronic equipment provided therewith - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily manufacture micro lenses while controlling a form of a curved lens surface of each micro lens. <P>SOLUTION: The manufacturing method of the micro lenses includes a process for forming a positive type resist on a substrate, a process for forming in the resist concave parts having curved lens surfaces corresponding to the micro lenses by underexposing an area corresponding to a lens forming area of the substrate in the resist with an exposure level at which the resist is not etched through and also performing development, and a process for transferring the concave parts onto the lens forming area by providing dry etching to the resist and the substrate. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

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

  As this type of electro-optical device, for example, there is a liquid crystal device in which a liquid crystal is sandwiched as an electro-optical material between an element substrate and a counter substrate which are arranged to face each other. In such a liquid crystal device, as disclosed in Patent Document 1 or Patent Document 2, a microlens corresponding to each pixel is formed on the counter substrate or the element substrate, or a plurality of such microlenses are formed. A microlens array plate with a built-in is attached. By using such a microlens array, bright display is realized in the electro-optical device.

  Here, the microlens is manufactured as follows. That is, first, on a transparent substrate, for example, a mask having a hole at a position corresponding to the center of the microlens to be formed is formed. Next, the transparent substrate is wet-etched through this mask to dig a spherical recess that defines the curved surface of the microlens. Then, after removing the mask, the concave portion is filled with a transparent medium having a high refractive index. Thereby, a microlens having a hemispherical lens curved surface is formed in the recess.

  However, the lens curved surface of the microlens is not necessarily an optically ideal shape as a hemispherical surface. Patent Document 1 or 2 discloses a method for manufacturing a microlens having an aspheric lens curved surface.

  Furthermore, Patent Document 3 or 4 discloses a method of manufacturing a microlens having a spherical or aspherical lens curved surface using a transfer technique. According to Patent Document 3 or 4, a resist is applied on a substrate on which a microlens is to be formed, and after the resist is patterned, the resist is formed into a smooth convex shape by heating appropriately. Thereafter, the resist and the substrate are etched until the convex shape of the resist is transferred to the substrate.

JP 2003-279949 A JP 2003-139915 A JP-A-6-250002 JP-A-6-194502

  However, according to the method disclosed in Patent Document 1 or Patent Document 2, a complicated process is required to form a microlens. On the other hand, according to the method disclosed in Patent Document 3 or 4, it is difficult to accurately realize shape control such as the size and curvature of each microlens.

  The present invention has been made in view of the above-described problems, and a microlens manufacturing method capable of easily manufacturing a microlens while controlling the shape of the curved surface of each microlens, and the manufacturing method thereof It is an object of the present invention to provide a manufactured microlens, an electro-optical device including the microlens, and an electronic apparatus including the electro-optical device.

  In order to solve the above problems, a first manufacturing method of a microlens according to the present invention includes a step of forming a positive resist on a substrate, and a region in the resist corresponding to a lens formation region of the substrate. Performing underexposure with an exposure amount that does not completely remove the resist, and developing to form a recess having a curved surface corresponding to the lens curved surface of the microlens in the resist, and the resist and the substrate. And transferring the concave portion to the lens forming region by performing dry etching.

  According to the first method for manufacturing a microlens of the present invention, a positive resist is formed on a substrate such as a quartz substrate or a glass substrate by, for example, spin coating. In addition, you may pre-bake before the underexposure mentioned later. At this time, the resist is formed to be thicker than that used as a simple mask so that a recess having a predetermined depth can be formed without penetrating into the resist as will be described later.

  Subsequently, the resist is under-exposed by, for example, a photolithography method and developed. Underexposure is performed with a relatively small amount of exposure that does not completely fill the resist. The development is performed, for example, by controlling the development time so as not to remove the resist. In the region corresponding to the lens formation region of the substrate in the resist, development proceeds corresponding to the exposure distribution at the time of underexposure, and as a result, a concave portion having a curved surface reflecting the exposure distribution is formed. The curved surface of the concave portion corresponds to the lens curved surface of the microlens as will be described later. Therefore, by changing the exposure distribution of the region in the resist and controlling the development time, the depth of the recess and the radius of curvature of the curved surface can be controlled, and the lens curved surface having a desired curvature is formed as a spherical surface or an aspherical surface. It becomes possible to do.

  Thereafter, by performing dry etching on the resist and the substrate, the concave portions formed in the resist are dug into the lens formation region of the substrate and the resist is removed. At this time, the etching selectivity between the substrate and the resist is preferably 1: 1. Therefore, according to such a transfer process, it is possible to form the concave portion having the lens curved surface of the microlens on the substrate relatively easily.

  In order to solve the above problems, a second manufacturing method of a microlens of the present invention includes a step of forming a positive resist on a substrate, and a region of the resist corresponding to a lens formation region of the substrate. Underexposure with an exposure amount that does not completely remove the resist, and development is performed to form an initial hole having an aspheric curved surface corresponding to the lens curved surface of the microlens in the resist, and the resist and the resist A step of transferring the initial hole to the lens forming region by performing dry etching on the substrate; and an isotropic etching of the substrate to dig up the initial hole to thereby form the lens curved surface. Forming a recess having the above in the substrate.

  According to the second method for producing a microlens of the present invention, underexposure is performed on a region of the resist formed on the substrate corresponding to the lens formation region of the substrate and developed. As a result, in the region of the resist, development proceeds corresponding to the exposure distribution at the time of underexposure, and an initial hole having a shape reflecting the exposure distribution is formed. Therefore, by controlling the development time while changing the exposure distribution of the region in the resist during underexposure, the shape of the curved surface of the initial hole similar to the concave portion can be controlled. As a result, the curved surface of the initial hole can be formed as an aspherical surface.

  Thereafter, by performing dry etching on the resist and the substrate, the initial holes formed in the resist are dug into the lens formation region of the substrate and the resist is removed.

  Subsequently, when the substrate is subjected to, for example, wet etching as isotropic etching, the initial hole is isotropically dug to form a recess. The shape of the recess is similar to the initial hole. That is, by using a relatively small initial hole, it is possible to form a relatively large recess that is similar to this. The curved surface of the recess defines the lens curved surface of the microlens. When the substrate is retracted in a large amount by the isotropic etching, a mask may be used so that the shape of each recess is not impaired.

  Therefore, according to the second manufacturing method of the microlens of the present invention, the concave portion having the lens curved surface of the microlens can be formed on the substrate relatively easily. Further, by controlling the shape of the curved surface of the initial hole as described above, the lens curved surface of the microlens can be formed as an aspherical surface having a desired curvature. Here, as compared with the first manufacturing method of the present invention described above, according to the second manufacturing method, an initial hole having a smaller size is formed in the resist as a similar shape of the recess. Can be made thinner.

  In one aspect of the second manufacturing method of the microlens of the present invention, the isotropic etching is performed by wet etching.

  According to this aspect, the initial hole formed in the substrate can be dug isotropically.

  In another aspect of the first or second manufacturing method of the microlens of the present invention, the concave portion is a substantially quadrangular concave portion when seen in a plan view.

  According to this aspect, it is possible to form each recess so that the recesses adjacent to each other share one side when viewed in a plan view. Therefore, according to this aspect, it is possible to widen an effective area as a lens in each microlens.

  In another aspect of the first or second manufacturing method of the microlens of the present invention, the underexposure is performed by changing the exposure distribution of the region in the resist, thereby controlling the shape of the curved surface of the recess. .

  According to this aspect, the recess or initial hole formed in the resist has a curved surface that reflects the exposure distribution during underexposure. Therefore, by changing the exposure distribution at the time of underexposure, the depth of the concave portion or the initial hole and the curvature radius of the curved surface can be controlled.

  In another aspect of the first or second manufacturing method of the microlens of the present invention, the underexposure is performed using a projection lens that projects an image of a pattern corresponding to the shape of the microlens onto the region of the resist. And adjusting the depth of focus of the projection lens to control the shape of the curved surface of the concave portion.

  According to this aspect, at the time of underexposure, the depth of focus of the projection lens can be adjusted using, for example, a diaphragm, so that it can be changed between a state that matches the resist surface and a state that does not match. Then, underexposure is performed while maintaining either the state where the projection lens is focused on the resist surface or the state where it is not. Alternatively, underexposure may be performed while alternately repeating a state in which the projection lens is focused on the resist surface and a state in which the projection lens is out of focus. Thereby, the exposure distribution of the region in the resist can be changed. Therefore, according to this aspect, the depth of the concave portion or the initial hole and the curvature radius of the curved surface can be controlled.

  In another aspect of the first or second manufacturing method of the microlens of the present invention, the resist is subjected to heat treatment after the development and before the transfer step.

  According to this aspect, the shape of the recess or initial hole formed in the resist can be deformed by performing the heat treatment at a temperature equal to or higher than the heat deformation temperature. As a result, the curved surface of the recess can be formed as a spherical surface or an aspherical surface. Alternatively, the curved surface of the initial hole can be formed as an aspherical surface.

  In another aspect of the first or second manufacturing method of the microlens of the present invention, the transfer step is performed with an etching selection ratio of 1: 1 between the substrate and the resist.

  According to this aspect, the concave portion or initial hole formed in the resist can be dug into the lens formation region of the substrate, and the resist can be removed. Ideally, the selection ratio may be ideally 1: 1. However, as long as the effect that the resist can be removed while duplicating the concave portion or the initial hole is obtained, the selection ratio is slightly different from 1: 1. Even in this case, “selection ratio is 1: 1” in this embodiment.

  In another aspect of the first or second manufacturing method of the microlens of the present invention, the substrate is made of a transparent substrate, and a transparent medium having a refractive index larger than that of the transparent substrate in the recess formed in the substrate. The method further includes the step of putting

  According to this aspect, since the transparent medium having a higher refractive index is placed in the concave portion formed in the substrate made of the transparent substrate, the microlens is used as a convex lens having an optical condensing function on the transparent substrate. Manufacturable. 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.

  In order to solve the above problems, the microlens of the present invention is manufactured by the above-described first or second method for manufacturing the microlens of the present invention (including various aspects thereof).

  In the microlens of the present invention, a microlens having a lens curved surface having an optically optimal shape can be realized.

  In order to solve the above problems, an electro-optical device of the present invention includes the above-described microlens of the present invention, a display electrode facing the microlens, and a wiring or an electronic element connected to the display electrode. .

  The electro-optical device of the present invention includes, for example, an island-shaped pixel electrode arranged as a “display electrode” for each pixel, a wiring such as a scanning line and a data line, and a thin film transistor (Thin Film Transistor; And an electronic device such as an active matrix driving type liquid crystal device in which electronic elements of a thin film diode (hereinafter referred to as “TFD”) are connected.

  Since the electro-optical device of the present invention includes the above-described microlens of the present invention, it is possible to enjoy better condensing characteristics, optical path changing characteristics, and the like. More specifically, for example, by condensing the display light toward the non-opening area of each pixel toward the opening area, the use efficiency of the display light can be increased and brighter display can be achieved. Alternatively, for example, it is possible to disperse light incident from the outside to each pixel, and it is possible to prevent a situation where light is concentrated and irradiated at one point in each pixel. As a result, the life of the electro-optical device can be extended.

  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.

  Since the electronic apparatus of the present invention includes the above-described electro-optical device of the present invention, for example, a projection display device, a television, a mobile phone, an electronic notebook, a word processor, and a viewfinder type that can extend the life. Alternatively, various electronic devices such as a monitor direct-view video tape recorder, a workstation, a videophone, a POS terminal, and a touch panel can be realized. In addition, as an electronic apparatus of the present invention, for example, an electrophoretic device such as electronic paper, an electron emission device (Field Emission Display and a Conduction Electron-Emitter Display), an electrophoretic device, and an apparatus using the electron emission device, DLP (Degital Light Processing) and the like can also be realized.

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

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

<1: First Embodiment>
1st Embodiment which concerns on the manufacturing method of the micro lens of this invention is described with reference to FIGS.

<1-1: Microlens array plate>
First, a microlens array plate that can be manufactured by the method for manufacturing a microlens of the present invention will be described with reference to FIGS. Here, FIG. 1 is a schematic perspective view of a microlens array plate, and FIG. 2A is a partially enlarged plane showing an enlarged portion related to four microlenses in the microlens array plate of the present embodiment. FIG. 2B is a partially enlarged cross-sectional view of the microlens array plate of the present embodiment.

  As shown in FIG. 1, the microlens array plate 20 of the present embodiment includes a transparent plate member 210 made of, for example, a quartz plate or a glass plate, which is covered with a cover glass 200. In the transparent plate member 210, a large number of concave depressions, that is, depressions are formed 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.

  Thus, 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. 2A and 2B, the curved surface of each microlens 500 is generally defined by a transparent plate member 210 and an adhesive layer 230 having different refractive indexes. More specifically, each concave portion has a lens curved surface of the microlens 500. Each microlens 500 is constructed as a plano-convex lens having a lens curved surface defined by a recess.

  In the present embodiment, in particular, since the lens is manufactured by the manufacturing method unique to the present invention as described later, the lens curved surface of the microlens 500 can be optically optimized. Therefore, in the microlens array plate 20, it is possible to realize more excellent condensing characteristics or optical path changing characteristics.

  In the present embodiment, it is preferable that the recess described with reference to FIGS. 2A and 2B has a substantially rectangular shape when seen in a plan view. If it does in this way, it will become possible to form each recessed part so that the recessed part adjacent to each other may share one side seeing planarly. Therefore, it is possible to widen an effective area as a lens in each microlens 500.

<1-2: Electro-optical device>
Next, the overall configuration of the electro-optical device according to the first embodiment of the invention will be described with reference to FIGS. FIG. 3 is a plan view of the TFT array substrate as viewed from the above-described microlens array plate used as a counter substrate together with each component formed thereon, and FIG. 4 is a plan view of FIG. It is H 'sectional drawing. Here, a TFT active matrix driving type liquid crystal device with a built-in driving circuit, which is an example of an electro-optical device, is taken as an example.

  3 and 4, in the electro-optical device according to this 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, and is applied on the TFT array substrate 10 in the manufacturing process and then cured by ultraviolet irradiation, heating, or the like. It is. 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. That is, the electro-optical device according to the present embodiment is suitable for a small and enlarged display for a projector light valve.

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

  Of the peripheral regions located around the image display region 10 a, the data line driving circuit 101 and the external circuit connection terminal 102 are arranged on one side of the TFT array substrate 10 in the region located outside the seal region where the sealing material 52 is disposed. It is provided along. The scanning line driving circuit 104 is provided along two sides adjacent to the one side so as to be covered with the frame light shielding film 53. Further, in order to connect the two scanning line driving circuits 104 provided on both sides of the image display area 10a in this way, the TFT array substrate 10 is covered with the frame light shielding film 53 along the remaining side. A plurality of wirings 105 are provided.

  In addition, at the four corners of the microlens array plate 20, vertical conductive members 106 functioning as vertical conductive terminals between the two substrates are disposed. On the other hand, the TFT array substrate 10 is provided with vertical conduction terminals in a region facing these corner portions. As a result, electrical conduction can be established between the TFT array substrate 10 and the microlens array plate 20.

  In FIG. 4, 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, although a detailed configuration will be described later, on the microlens array plate 20, in addition to the counter electrode 21, a lattice-shaped or striped light-shielding film 23 and an alignment film are formed in the uppermost layer portion. 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.

  In addition to the data line driving circuit 101, the scanning line driving circuit 104, and the like, the image signal on the image signal line is sampled and supplied to the data line on the TFT array substrate 10 shown in FIGS. Sampling circuit, precharge circuit for supplying a precharge signal of a predetermined voltage level to a plurality of data lines in advance of the image signal, for inspecting the quality, defects, etc. of the electro-optical device during production or at the time of shipment An inspection circuit or the like may be formed.

  Next, the circuit configuration and operation of the electro-optical device configured as described above will be described with reference to FIG. FIG. 5 shows an equivalent circuit of various elements, wirings, and the like in a plurality of pixels formed in a matrix that forms the image display area of the electro-optical device.

  In FIG. 5, each of the plurality of pixels formed in a matrix that forms the image display region 10 a of the electro-optical device according to the present embodiment includes a pixel electrode 9 a and a TFT 30 for switching control of the pixel electrode 9 a. The data line 6 a formed and supplied with an image signal is electrically connected to the source of the TFT 30. The image signals S1, S2,..., Sn written to the data lines 6a may be supplied line-sequentially in this order, or may be supplied for each group to a plurality of adjacent data lines 6a. Good.

  Further, the gate electrode 3a is electrically connected to the gate of the TFT 30, and the scanning signals G1, G2,..., Gm are pulse-sequentially applied in this order to the scanning line 11a and the gate electrode 3a at a predetermined timing. It is comprised so that it may apply. The pixel electrode 9a is electrically connected to the drain of the TFT 30, and the image signal S1, S2,..., Sn supplied from the data line 6a is obtained by closing the switch of the TFT 30 as a switching element for a certain period. Write at a predetermined timing.

  A predetermined level of the image signals S1, S2,..., Sn written in the liquid crystal as an example of the electro-optical material via the pixel electrode 9a is between the counter electrode 21 formed on the microlens array plate 20 for a certain period. Retained. The liquid crystal modulates light and enables gradation display by changing the orientation and order of the molecular assembly depending on the applied voltage level. In the normally white mode, the transmittance for incident light is reduced according to the voltage applied in units of each pixel, and in the normally black mode, the light is incident according to the voltage applied in units of each pixel. The light transmittance is increased, and light having a contrast corresponding to the image signal is emitted from the electro-optical device as a whole.

  In order to prevent the image signal held here 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. The storage capacitor 70 is provided side by side along the scanning line 11a, and includes a capacitor electrode 300 including a fixed potential side capacitor electrode and fixed at a constant potential.

  The detailed configuration and function of the microlens array plate 20 provided in the above-described electro-optical device will be described with reference to FIGS. FIG. 6 is a plan view schematically showing the configuration of the light shielding film 23 in the microlens array plate 20, and FIG. 7 is a diagram showing in more detail the configuration of the cross section shown in FIG. 4 for a plurality of pixels. FIG. 6 is a cross-sectional view for explaining the function of each microlens 500.

  In the microlens array plate 20, a light shielding film 23 having a grid-like plane pattern as shown in FIG. In the microlens array plate 20, a non-opening area is defined by the light shielding film 23, and an area delimited by the light shielding film 23 is an opening area 700. The light shielding film 23 is formed in a stripe shape, and the non-opening region is defined by the light shielding film 23 and various components such as the capacitor electrode 300 and the data line 6a provided on the TFT array substrate 10 side. Also good.

  Each microlens 500 is arranged so as to correspond to each pixel. More specifically, as shown in FIG. 7, in the microlens array plate 20, the microlens is formed in an area at least partially including an opening area 700 and a non-opening area located around the opening area 700 for each pixel. 500 is formed.

  In FIG. 7, the counter electrode 21 made of a transparent conductive film is formed on the transparent plate member 210 so as to cover the light shielding film 23. Further, an alignment film (not shown in FIG. 7) is formed on the counter electrode 21.

  On the other hand, in FIG. 7, pixel electrodes 9 a are formed in regions corresponding to the respective opening regions 700 on the TFT array substrate 10. In addition, the pixel switching TFT 30, the various wirings such as the scanning line 11a and the data line 6a for driving the pixel electrode 9a, and the electronic elements such as the storage capacitor 70 are formed in the non-opening region. With this configuration, the pixel aperture ratio in the electro-optical device can be maintained relatively large. Further, although not shown in FIG. 7, an alignment film is provided on the pixel electrode 9a.

  In FIG. 7, light such as projection light incident on the microlens array plate 20 is collected by each microlens 500. In FIG. 7, the appearance of light collected by the microlens 500 is schematically shown by a one-dot chain line. Then, the light collected by each microlens 500 is transmitted through the liquid crystal layer 50 to be applied to the pixel electrode 9a, passes through the pixel electrode 9a, and is emitted from the TFT array substrate 10 as display light. Therefore, the light directed to the non-opening region among the light incident on the microlens array plate 20 can also be made incident on the opening region 700 by the condensing action of the microlens 500, so that the effective aperture ratio in each pixel is increased. Can do. That is, it is possible to display a brighter image by increasing the light utilization efficiency.

  Further, as described above, since the lens curved surface of the microlens 500 can be optically optimized, it is possible to enjoy better condensing characteristics, optical path changing characteristics, and the like. Therefore, for example, the microlens 500 can disperse light incident on each pixel, and can prevent a situation where light is concentrated and irradiated at one point in each pixel. As a result, the life of the electro-optical device can be extended.

  In the electro-optical device described above, instead of providing the data line driving circuit 101 and the scanning line driving circuit 104 on the TFT array substrate 10, for example, a TFT array is mounted on a driving LSI mounted on a TAB (Tape Automated Bonding) substrate. You may make it connect electrically and mechanically via the anisotropic conductive film provided in the peripheral part of the board | substrate 10. FIG. Further, for example, a TN (Twisted Nematic) mode, a VA (Vertical Aligned) mode, and a PDLC (Polymer Dispersed) are respectively provided on the side on which the projection light of the microlens array plate 20 is incident and on the side on which the emission light of the TFT array substrate 10 is emitted. A polarizing film, a retardation film, a polarizing plate, and the like are arranged in a predetermined direction according to an operation mode such as a liquid crystal mode or a normally white mode / normally black mode.

  In the electro-optical device described above, the microlens array plate 20 as shown in FIGS. 1 and 2 is used as the counter substrate. However, the microlens array plate 20 is used as the TFT array substrate 10. Is also possible. Alternatively, it is possible to attach the microlens array substrate 20 to the TFT array substrate 10 side by simply using a glass substrate or the like on which the counter electrode or alignment film is formed as the counter substrate (not the microlens array plate 20). It is. That is, the microlens of the present invention can be built or attached to the TFT array substrate 10 side.

<1-3: Microlens array manufacturing method>
Next, a method for manufacturing the microlens array plate 20 according to the present embodiment will be described with reference to FIG. FIG. 8 is a process diagram schematically showing the cross-sectional configuration of the microlens array plate 20 in each step of the manufacturing process.

  First, in FIG. 8A, a positive resist 810 is formed on a transparent plate member 210a such as a quartz plate or a glass plate by, eg, spin coating. The resist 810 is formed to be thicker than that used as a simple mask so that a recess 820 having a predetermined depth can be formed without penetrating into the resist as will be described later. Note that after the resist 810 is formed, pre-baking may be performed before underexposure described later. In each of FIGS. 8A to 8C, the lens forming region 800 in which one microlens 500 is formed in the transparent plate member 210a is specifically shown.

  Subsequently, in FIG. 8B, the resist 810 is under-exposed by, eg, photolithography, and developed. Here, the underexposure will be described in detail with reference to FIGS. 9A and 9B. FIG. 9A is a diagram schematically showing a planar configuration of a reticle used in underexposure, and FIG. 9B is a schematic diagram for specifically explaining underexposure.

  FIG. 9A shows a planar configuration of a reticle 900 that is used when under-exposure is performed on one lens formation region 800. In the reticle 900, for example, a circular pattern opening 902 corresponding to the microlens 500 is provided.

  FIG. 9B schematically shows the cross-sectional configuration of the microlens array plate 20 and the cross-sectional configuration of the reticle 900 in one lens formation region 800 at the time of underexposure. Underexposure is performed on an area corresponding to the lens formation area 800 in the resist 810 through the opening 902 of the reticle 900. At this time, the exposure amount is adjusted to a relatively small amount that does not completely fill the resist.

  Further, in FIG. 9B, an example of the exposure distribution in the resist 810 at this time is schematically shown as a light intensity distribution. According to this light intensity distribution, the value of the light intensity decreases with increasing distance from the center around the portion where the light intensity is maximum. When development is performed after completion of underexposure, the development proceeds corresponding to such a light intensity distribution. That is, the development proceeds fastest at a portion where the light intensity is maximum in the resist 810, and progresses more slowly as the distance from the portion to the periphery increases. The development is performed to such an extent that the development time is controlled so that the resist 810 cannot be removed.

  Therefore, after the development is completed, as shown in FIG. 8B, the resist 810 has a concave portion 820 having a curved surface reflecting the exposure distribution. The curved surface of the recess 820 corresponds to the lens curved surface of the microlens 500 as described later. Therefore, by changing the exposure distribution as described above and controlling the development time, the depth of the recess 820 and the radius of curvature of the curved surface can be controlled, and the lens curved surface having a desired curvature is formed as a spherical surface or an aspherical surface. It becomes possible to do.

  Here, it is preferable that the exposure distribution is controlled as follows. For example, the exposure distribution is changed by performing underexposure using a projection lens that projects the pattern of the opening 902 in the reticle 900 on the resist 810 and adjusting the depth of focus of the projection lens by the reduced projection exposure method. Let More specifically, by adjusting the depth of focus of the projection lens using, for example, a diaphragm, it is possible to change between a state that matches the surface of the resist 810 and a state that does not match. Then, underexposure is performed while maintaining either the state where the projection lens is focused on the surface of the resist 810 or the state where it is not. Alternatively, underexposure may be performed while alternately repeating a state in which the projection lens is focused on the surface of the resist 810 and a state in which the projection lens is not aligned.

  Subsequently, in FIG. 8C, by performing dry etching on the resist 810 and the transparent plate member 210a, the concave portion 820 formed in the resist 810 is dug into the lens formation region 800 in the transparent plate member 210a. When dry etching is performed with an etching selection ratio of 1: 1 between the transparent plate member 210a and the resist 810, the recess 820 is transferred to the transparent plate member 210a and the resist 810 can be removed. Therefore, according to such a transfer process, the concave portion 220 having the lens curved surface of the microlens 500 can be formed relatively easily.

  Next, in FIG. 8D, a thermosetting transparent adhesive is applied to the surface of each recess 220, and a cover glass 200 made of neoceram, quartz or the like is pressed and cured. As a result, the microlens 500 in which the adhesive layer 230 is filled in each concave portion 220 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.

<1-3: Modification>
A modification of the method for manufacturing the microlens array plate 20 of the present embodiment will be described. FIG. 10 is a process diagram schematically showing the configuration of the cross section of the microlens array plate 20 in one lens formation region 800 in order in each process of the manufacturing process according to this modification.

  FIG. 10A shows a state in which the concave portion 820a is formed in the resist 810, similarly to the process described with reference to FIG.

  In FIG. 10B, before the recess 820a is transferred to the transparent plate member 210a, the resist 810 is heated at a temperature equal to or higher than the heat deformation temperature. As a result, a concave portion 820 having a spherical or aspheric curved surface can be formed.

<2: Second Embodiment>
A second embodiment according to the method for manufacturing a microlens of the present invention will be described. In 2nd Embodiment, the manufacturing process which forms a recessed part in a transparent plate member differs from 1st Embodiment. Accordingly, the manufacturing process will be described in detail with reference to FIG. 11 only for the differences from the first embodiment. FIG. 11 is a process diagram schematically illustrating the cross-sectional configuration of the microlens array plate in order in each process of the manufacturing process according to the second embodiment. In FIG. 11, the same parts as those in the first embodiment are denoted by the same reference numerals, and redundant description is omitted.

  First, in FIG. 11A, a positive resist 810b is formed on the transparent plate member 210a. Compared to the first embodiment, a small initial hole 820b as described later is formed in the resist 810b, so that the thickness of the resist 810b can be reduced.

  Next, in FIG. 11B, the resist 810b is under-exposed and developed. At this time, in the region corresponding to the lens formation region 800 in the resist 810b, development proceeds corresponding to the exposure distribution at the time of underexposure, and an initial hole 820b having a shape reflecting the exposure distribution is formed. Therefore, the shape of the curved surface of the initial hole 820b can be controlled by controlling the development time while changing the exposure distribution in the resist 810b. As a result, the curved surface of the initial hole 820b can be formed as an aspherical surface.

  Thereafter, in FIG. 11C, by performing dry etching on the resist 810b and the transparent plate member 210a, the initial hole 820b formed in the resist 810b is dug into the lens forming region 800 in the transparent plate member 210a. The resist 810b is removed.

  Subsequently, in FIG. 11D, when the transparent plate member 210a is subjected to, for example, wet etching as isotropic etching, the initial hole 220bb formed in the transparent plate member 210a shown in FIG. The recess 220b is formed by digging in the direction. The shape of the recess 220b is similar to that of the initial hole 220bb. That is, by using the relatively small initial hole 220bb, it is possible to form a relatively large recess 220b that is similar to this. The curved surface of the concave 220b defines the lens curved surface of the microlens 500. When the transparent plate member 210a is retracted in a large amount by the isotropic etching, a mask may be used so that the shape of each recess 220b is not impaired.

  Therefore, according to the second embodiment, the recess 220b can be formed relatively easily. Further, by controlling the shape of the curved surface of the initial hole 820b formed in the resist 810b as described above, the lens curved surface of the microlens 500 can be formed as an aspherical surface having a desired curvature.

<3: Electronic equipment>
Next, an overall configuration, particularly an optical configuration, of an embodiment of a projection color display device as an example of an electronic apparatus using the above-described electro-optical device as a light valve will be described. FIG. 12 is a schematic cross-sectional view of the projection type color display device.

  In FIG. 12, a liquid crystal projector 1100, which is an example of a projection type color display device, prepares three liquid crystal modules including a liquid crystal device having a drive circuit mounted on a TFT array substrate, and RGB light valves 100R, 100G, and The projector is configured as 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, the 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. The light is divided into B and led to the light valves 100R, 100G and 100B corresponding to the respective colors. 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. 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 via the projection lens 1114.

  The present invention is not limited to the above-described embodiment, and can be appropriately changed within the scope of the invention or the concept that can be read from the entire claims and the specification, and the microlens with such a change can be changed. A manufacturing method, a microlens manufactured by the manufacturing method, an electro-optical device including the microlens, and an electronic apparatus including the electro-optical device are also included in the technical scope of the present invention.

It is a schematic perspective view of a micro lens array board. FIG. 2A is a partially enlarged plan view showing an enlarged portion related to four microlenses in the microlens array plate, and FIG. 2B is a partially enlarged sectional view of the microlens array plate. . It is a top view which shows the whole structure of an electro-optical apparatus. It is H-H 'sectional drawing of FIG. 2 is an equivalent circuit of various elements, wirings, and the like in a plurality of pixel portions formed in a matrix that forms an image display region of an electro-optical device. It is a top view which shows typically the structure of the light shielding film in a micro lens array board. It is sectional drawing for demonstrating the function of each micro lens. It is manufacturing process sectional drawing which shows the manufacturing method of the micro lens array board which concerns on 1st Embodiment later on. FIG. 9A is a diagram illustrating a planar configuration of the reticle, and FIG. 9B is a schematic diagram for specifically explaining the underexposure. It is process drawing which shows roughly the structure of the cross section of a microlens array board later on in each process of the manufacturing process which concerns on a modification. It is process drawing which shows roughly the structure of the cross section of the micro lens array board in each process of the manufacturing process which concerns on 2nd Embodiment later on. 1 is a schematic cross-sectional view showing a color liquid crystal projector as an example of a projection type color display device which is an embodiment of an electronic apparatus of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 20 ... Micro lens array board 200 ... Cover glass 210, 210a ... Transparent plate member 220, 220b ... Recessed part 230 ... Adhesive layer 500 ... Micro lens 800 ... Lens formation area 810, 810b ... Resist

Claims (12)

Forming a positive resist on the substrate;
A concave portion having a curved surface corresponding to the lens curved surface of the microlens is formed in the resist corresponding to the lens forming region of the substrate by performing underexposure and developing with an exposure amount that does not completely extract the resist. Forming in the resist;
And a step of transferring the concave portion to the lens forming region by performing dry etching on the resist and the substrate. Forming a positive resist on the substrate;
An aspherical curved surface corresponding to the lens curved surface of the microlens is formed by performing underexposure and developing with respect to the region corresponding to the lens formation region of the substrate in the resist with an exposure amount that does not completely extract the resist. Forming an initial hole in the resist with
Transferring the initial hole to the lens forming region by performing dry etching on the resist and the substrate;
Forming a recess having the curved lens surface on the substrate by subjecting the substrate to isotropic etching and digging the initial hole. The method of manufacturing a microlens according to claim 2, wherein the isotropic etching is performed by wet etching.   The method of manufacturing a microlens according to any one of claims 1 to 3, wherein the concave portion is a concave portion having a substantially square shape when seen in a plan view. 5. The microlens according to claim 1, wherein the underexposure is performed by changing an exposure distribution of the region in the resist to control a curved surface shape of the concave portion. Manufacturing method. Performing the underexposure using a projection lens that projects an image of a pattern corresponding to the shape of the microlens onto the region of the resist;
The method of manufacturing a microlens according to any one of claims 1 to 4, wherein the shape of the curved surface of the concave portion is controlled by adjusting a depth of focus of the projection lens. The microlens manufacturing method according to claim 1, wherein the resist is subjected to a heat treatment after the development and before the transfer step. The microlens manufacturing method according to claim 1, wherein the transfer step is performed with an etching selection ratio of the substrate and the resist of 1: 1.   9. The method according to claim 1, further comprising a step of placing a transparent medium having a refractive index higher than that of the transparent substrate in the concave portion formed in the substrate. The method for producing a microlens according to one item.   The microlens manufactured by the manufacturing method of the microlens as described in any one of Claim 1 to 9. A microlens according to claim 10;
A display electrode facing the microlens;
An electro-optical device comprising: a wiring or an electronic element connected to the display electrode. An electronic apparatus comprising the electro-optical device according to claim 11.

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