JP4333373B2 - Microlens manufacturing method, microlens, and electro-optical device and electronic apparatus including the same - Google Patents

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 disclosed in Patent Document 1 to Patent Document 3, in an electro-optical device such as a liquid crystal device, for example, a microlens corresponding to each pixel is formed on a counter 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. Furthermore, in order to improve the contrast in each pixel, each microlens is preferably formed as a lens having a large curvature radius.

  Here, the microlens is manufactured as follows. That is, first, on a transparent substrate, for example, a mask having a plurality of openings provided in a region corresponding to a lens formation region where a microlens is formed is formed. Next, the transparent substrate is wet-etched through this mask to dig a recess corresponding to each opening. The concave portion has a shape corresponding to the lens curved surface of the microlens. Then, after removing the mask, an adhesive composed of a transparent resin having a high refractive index is filled in each recess. Subsequently, the cover glass is bonded to the transparent substrate via the adhesive.

  According to such a manufacturing method, the microlens is formed by the adhesive filled in the recess. In order to form a microlens having a large curvature radius, it is necessary to dig deeper into the recess. Therefore, the thickness of the adhesive sandwiched between the cover glass and the transparent substrate is also increased, and there is a risk that the assembly accuracy of the electro-optical device is deteriorated due to thermal expansion of the adhesive.

  In order to reduce the thickness of the adhesive, the above-described mask is formed only in the lens formation region, the concave portion is formed and the non-lens formation region is cut, and the height of the non-lens formation region is equal to the edge of the concave portion. A method of increasing the height can be considered.

  Further, in Patent Document 1 or 2, in order to reduce the thickness of the adhesive, the following two types of etching are performed to make the height of the non-lens formation region equal to the edge of the recess. . That is, the first etching is performed on the transparent substrate through the mask to form each concave portion as an initial hole, then the mask is removed, and the second etching is further performed on the transparent substrate to form each initial hole. A lens curved surface with a large curvature radius is formed by digging.

JP 2001-194509 A JP 2000-231007 A Japanese Patent No. 3071045

  However, if the mask is formed only in the lens formation region, the mask may be peeled off as the etching progresses. In addition, according to the methods disclosed in Patent Documents 1 and 2, although the radius of curvature of each recess is increased, the shape of the recess formed as the initial hole by the second etching is changed. Further, according to Patent Document 1, a region that does not function as a lens is provided, which is referred to as a “column” with respect to the four corners of the microlens.

  The present invention has been made in view of the above-described problems. A microlens manufacturing method capable of manufacturing a microlens having a large curvature radius and a small thickness, a microlens manufactured by the manufacturing method, It is an object of the present invention to provide an electro-optical device including a microlens and an electronic apparatus including the electro-optical device.

  In order to solve the above problems, the first microlens manufacturing method of the present invention includes a step of forming a plurality of concave portions each having a lens curved surface of a microlens in a lens forming region on one surface of the transparent substrate, A step of forming a protective film by filling the recesses with a protective material, and a polishing process for the one surface so that a non-lens forming region located around the lens forming region on the one surface is retracted together with the protective film. And removing the protective film that has been retracted by the polishing process, and filling the plurality of recesses with a transparent adhesive having a higher refractive index than the transparent substrate to form the microlenses. And a step of adhering a cover substrate formed of a transparent plate member to the transparent substrate via the adhesive.

  According to the first microlens manufacturing method of the present invention, for example, a mask in which a plurality of openings corresponding to a plurality of recesses is formed on one surface of a transparent substrate is passed through the plurality of openings. Etching is performed to form a plurality of concave portions in the lens forming region on the one surface. Each recess has a curved lens surface corresponding to the radius of curvature of the microlens. The greater the radius of curvature of the microlens, the greater the distance from the bottom of the recess to the one surface of the transparent substrate, that is, the depth of the recess.

  After forming a protective film composed of, for example, a resist as a protective material, one surface of the transparent substrate is subjected to, for example, a chemical mechanical polishing (CMP) process as a polishing process. By the polishing process, the protective film exposed on the one surface of the transparent substrate in addition to the non-lens forming region on the one surface of the transparent substrate is also polished back, and the edges of the plurality of recesses are exposed. Typically, when the non-lens forming region is polished to the height of the edges of the plurality of recesses, almost simultaneously with this, the edges of the plurality of recesses arranged in a matrix in a plan view are arranged in a lattice pattern. Will be exposed. Thus, the depth of each recess can be reduced by retreating the non-lens forming region on one surface of the transparent substrate by polishing. Moreover, since the protective film is formed, it is possible to prevent dust from adhering in each recess during the polishing process.

  In addition, it is preferable that the planar shape of the edge part of each recessed part is a rectangular shape. In this way, as compared with the case where a column (see Patent Document 1) is provided between adjacent microlenses as described above, each microlens can have a wide effective area as a lens. At this time, for example, if the concave portion is formed by wet etching as described above, the planar shape of the concave portion becomes a circle by wet etching until the concave portion adjacent to the upper and lower sides or the right and left contacts. If the wet etching is continued, the planar shape approaches a rectangular shape in which circles are connected. Further, when the concave portions adjacent to each other come into contact with each other, the planar shape of the concave portion becomes a rectangular shape thereafter. In any stage, the inner surface of the concave portion forms a part of a spherical surface, and as the etching continues, the radius of curvature of the spherical surface increases.

  After the polishing treatment, the protective film is removed from each recess, and a microlens is formed by filling the recess with an adhesive composed of a transparent resin. As a result, it is possible to form plano-convex microlenses each having a curved lens surface in the shape when the recesses are formed and having a relatively large radius of curvature.

  The thickness of the microlens is the depth of the recess after the polishing process. That is, the thickness of the microlens can be adjusted by adjusting the depth of the recess in the polishing process. Therefore, it is possible to form a microlens having a large curvature radius and a small thickness.

  Further, the cover substrate is bonded to the transparent substrate through an adhesive. As described above, the thickness of the adhesive sandwiched between the transparent substrate and the cover substrate can be reduced by adjusting the thickness of the microlens.

  Here, by increasing the radius of curvature of the microlens, a lens with less aberration can be formed. When the curvature radius of the microlens is changed, the focal length is also changed. The focal length is preferably adjusted by changing the thickness of the cover substrate. Moreover, it is preferable to adjust the thickness of a transparent substrate with this adjustment.

  In one aspect of the first microlens manufacturing method of the present invention, the step of performing the polishing process is performed by a chemical mechanical polishing process.

  According to this aspect, by performing the CMP process, one surface of the transparent substrate is flattened, that is, the depths of the recesses can be made equal.

  In order to solve the above problems, the second microlens manufacturing method of the present invention includes a step of forming a plurality of concave portions each having a lens curved surface of a microlens in a lens forming region on one surface of the transparent substrate, A step of forming a protective film by filling the concave portions with a protective material, and a step of performing an etching process on the one surface so as to recede the non-lens forming region located at least around the lens forming region on the one surface Removing the protective film and filling the plurality of recesses with a transparent adhesive having a refractive index larger than that of the transparent substrate to form the microlens, and the transparent through the adhesive. Adhering a cover substrate formed using a transparent plate member to the substrate.

  According to the second microlens manufacturing method of the present invention, it is possible to form a microlens having a large curvature radius and a small thickness, as in the first microlens manufacturing method described above.

  Here, in the second microlens manufacturing method of the present invention, the non-lens forming region on the one surface of the transparent substrate is retracted by wet etching or dry etching. As the protective material, a material having an etching rate substantially equal to or lower than that of the transparent substrate, that is, a material that is difficult to be etched is used. If the etching rates of the protective material and the transparent substrate are substantially the same, the protective film exposed on the one surface of the transparent substrate in addition to the non-lens forming region on the one surface of the transparent substrate also moves backward as in the above polishing process. . On the other hand, when the etching rate of the protective material is smaller than that of the transparent substrate, the non-lens forming region can be retreated exclusively with little or substantially no etching of the protective film in the lens forming region. In any case, since the protective film is removed in the process of forming the microlens, which is a subsequent process, there is no problem in the subsequent process of forming the microlens without performing an etching process.

  Therefore, according to the second method for manufacturing a microlens of the present invention, each recess is protected by the protective film, and etching is performed without changing the shape of the curved surface of the lens formed in the recess. The depth of can be reduced. In addition, since the protective film is formed, it is possible to prevent dust from adhering in each recess during etching.

  In one aspect of the second microlens manufacturing method of the present invention, the step of retracting the non-lens forming region to be etched is performed by wet etching or dry etching.

  According to this aspect, by performing wet etching or dry etching, it is possible to retract the non-lens forming region on one surface of the transparent substrate.

  In another aspect of the manufacturing method of the first or second microlens of the present invention, the step of forming the protective film includes, among the protective films continuously formed from the inside of each concave portion to the outside of the concave portion, The portion formed outside each recess is removed, and the portion formed in each recess remains.

  According to this aspect, the non-lens forming region on one surface of the transparent substrate is exposed from the protective film, and the one surface of the transparent substrate is subjected to polishing treatment or etching, thereby forming the shape of the lens curved surface in each concave portion. The non-lens forming region can be retracted without changing the.

  In another aspect of the manufacturing method of the first or second microlens of the present invention, the edge of each recess is exposed by the step of performing the polishing treatment or the step of performing the etching treatment.

  In this aspect, the non-lens formation region on one surface of the transparent substrate is retracted by polishing or etching until the edge of each recess is exposed. As a result, it is possible to prevent a situation in which one surface of the transparent substrate is excessively shaved by etching or polishing treatment and all of the plurality of recesses are damaged.

In another aspect of the first and second microlens manufacturing methods of the present invention, in the step of forming the plurality of recesses, each recess has an inner surface forming a part of a spherical surface and has a rectangular planar shape. And is formed adjacent to the other recesses on each side.

  According to this aspect, as compared with the case where the column is provided between the adjacent microlenses as described above, it is possible to widen the effective area as a lens in each microlens.

In another aspect of the manufacturing method of the first and second microlenses of the present invention, the step of forming the plurality of recesses is formed on the transparent substrate in a region corresponding to the lens formation region, respectively from the recesses. Forming a mask having a plurality of openings having a small planar size from the lens formation region to the non-lens formation region, and isotropic with respect to the transparent substrate through the plurality of openings A step of forming the plurality of recesses by performing etching, and a step of removing the mask.

  According to this aspect, by performing isotropic etching on one surface of the transparent substrate through the mask, a plurality of concave portions are formed in the lens forming region on the one surface.

  Since the plurality of openings in the mask are each formed smaller than the planar size of the recess, it is possible to form a curved lens surface in the recess. Further, since the mask is formed on one surface of the transparent substrate from the lens formation region to the non-lens formation region, it is possible to prevent the mask from being damaged as the etching progresses.

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

  In the microlens of the present invention, by forming a microlens having a large radius of curvature and a small thickness, it is possible to reduce the aberration in each microlens. Therefore, a microlens capable of increasing the light use efficiency is realized.

  In order to solve the above-described 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. .

  According to the electro-optical device of the present invention, since the microlens of the present invention described above is provided, the light utilization efficiency can be increased by the microlens, and the light transmittance and contrast in each pixel can be improved. Therefore, the electro-optical device of the present invention can perform high-quality image display.

  In addition, since the thickness of the adhesive constituting the microlens can be reduced, it is possible to reduce the influence of the stress and the expansion coefficient of the adhesive, and to improve the assembly accuracy in the electro-optical device. It becomes possible.

  Such an electro-optical device has an island-shaped pixel electrode arranged as a “display electrode” for each pixel, wiring lines such as scanning lines and data lines, and thin film transistors (Thin Film Transistors; hereinafter referred to as “TFT” as appropriate). And an electro-optical device such as an active matrix drive type liquid crystal device in which electronic elements of a thin film diode (hereinafter referred to as “TFD”) are connected.

  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 (including various aspects thereof).

  Since the electronic apparatus of the present invention includes the above-described electro-optical device of the present invention, a projection display device, a television, a mobile phone, an electronic notebook, a word processor, a view capable of performing high-quality image display. Various electronic devices such as a finder type or a monitor direct-view type 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 microlens manufacturing method of the present invention will be described with reference to FIGS.

  Here, FIG. 1A is a schematic perspective view of the microlens array plate, and FIG. 1B is a schematic perspective view showing the configuration of the A-A ′ cross section of FIG. FIG. 2A is a partially enlarged plan view showing an enlarged portion related to four microlenses in the microlens array plate of this embodiment, and FIG. 2B is a microscopic view of this embodiment. FIG. 2C is a partially enlarged sectional view of the lens array plate, and FIG. 2C is an enlarged perspective view schematically showing the three-dimensional shape of the lens surface of the microlens of the present embodiment. Further, FIG. 3A is a diagram schematically showing a cross-sectional shape of the microlens of the present embodiment, and FIG. 3B is a schematic diagram showing a cross-sectional shape of the microlens of the comparative example. FIG.

  As shown in FIG. 1A, the microlens array plate 20 of the present embodiment has a transparent substrate 210 made of, for example, a quartz plate and the like, and is bonded to the transparent substrate 210 with an adhesive 230 as will be described later. Cover glass 200 which is a “cover substrate”.

  In the present embodiment, in the lens forming region 20a of the microlens array plate 20, a large number of microlenses 500 arranged in a matrix in the following manner are formed. In FIG. 1B, the transparent substrate 210 has a large number of concave depressions, that is, depressions formed in a matrix. In each recess, a transparent adhesive layer 230 having a higher refractive index than that of the transparent plate member 210 is formed by curing an adhesive made of, for example, a photosensitive resin material, which bonds the cover glass 200 and the transparent plate member 210 to each other. Is filled. The microlens 500 is formed by the adhesive layer 230 filled in each recess.

  In the present embodiment, in particular, each microlens 500 has the following configuration because it is manufactured by a manufacturing method unique to the present invention as described later. As shown in FIG. 2B, the curved surface of each microlens 500 is generally defined by a transparent substrate 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.

  The cross-sectional shape of each microlens 500 will be described more specifically with reference to FIGS. 3 (a) and 3 (b). As shown in FIG. 3A, the lens curved surface of the microlens 500 forms a part of a hemispherical spherical surface having a radius R. Accordingly, the cross-sectional shape of the microlens 500 is an arc shape defined by a curve that is a part of a semicircle arc of the hemisphere R and a straight line that connects both ends of the curve, and the thickness a of the microlens 500 has a radius R. Smaller than.

  The concave portion that defines the cross-sectional shape of the microlens 500 is formed by performing isotropic etching on the transparent substrate 210 as described later. Normally, when the depth of each recess is to be formed as the thickness a of the microlens 500 shown in FIG. 3A by isotropic etching, the depth of the recess is reduced as shown in FIG. The value is a, and a lens curved surface constituting a hemisphere having a radius a is formed in the concave portion. That is, according to the manufacturing method of the present embodiment, it is possible to form the microlens 500 having a large radius of curvature and a small thickness as compared with the comparative example shown in FIG.

  Next, the planar shape of each microlens 500 will be described. As shown in FIG. 2A, the planar shape of each microlens 500 is preferably rectangular. The planar shape of each microlens 500 is defined by the edge of the recess. And the recessed part in which one microlens 500 shown in FIG. 2A is formed is adjacent to the recessed part in which another microlens 500 is formed, sharing an edge. FIG. 2C schematically shows the three-dimensional shape of the microlens 500 viewed from the lens curved surface side. In FIG. 2C, the four microlenses 500 adjacent to each other are formed by connecting lens curved surfaces to each other. Therefore, compared with the case where a column is provided between adjacent microlenses, each microlens 500 can have a wide effective area as a lens.

  As described above, when each microlens 500 is formed as a lens having a relatively large radius of curvature, the aberration in the microlens 500 can be reduced.

<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. 4 and 5. FIG. FIG. 4 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. 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.

  4 and 5, in the electro-optical device according to the present embodiment, the TFT array substrate 10 and the microlens array plate 20 used as the 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. 5, 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 an 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. 6 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. 6, 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 micro lens 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.

  A 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. 7 is a plan view schematically showing the arrangement relationship between the light shielding film 23 and the microlens 500 in the microlens array plate 20, and FIG. 8 shows the configuration of the cross section shown in FIG. It is a figure shown in detail, Comprising: It is sectional drawing for demonstrating the function of each micro lens 500. FIG.

  In FIG. 8, in the microlens array plate 20, a light shielding film 23 having a lattice-like plane pattern as shown in FIG. 7 is formed on a transparent substrate 210. 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, a rectangular shape 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. A microlens 500 having a planar shape is formed.

  In FIG. 8, the counter electrode 21 made of a transparent conductive film is formed on the transparent substrate 210 so as to cover the light shielding film 23. Further, an alignment film (not shown in FIG. 8) is formed on the counter electrode 21. In addition, a color filter may be formed in each opening region 700 on the transparent substrate 210.

  On the other hand, in FIG. 8, 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. 8, an alignment film is provided on the pixel electrode 9a.

  In FIG. 8, light such as projection light incident on the microlens array plate 20 is collected by each microlens 500. In FIG. 8, the appearance of light collected by the microlens 500 is schematically shown by an alternate long and short dash 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. Here, among the light incident on the microlens array plate 20, the light traveling toward the non-opening region can also be incident on the opening region 700 by the light condensing action of the microlens 500, thereby increasing the effective aperture ratio in each pixel. be able to. In addition, since each microlens 500 can be a lens with small aberration, the light use efficiency can be improved. Therefore, the light transmittance and contrast in each pixel can be improved, and as a result, high-quality image display can be performed.

  Furthermore, since the thickness of the adhesive layer 230 constituting the microlens 500 can be reduced, the influence of the stress and the expansion coefficient of the adhesive layer 230 can be reduced, and the assembly accuracy in the electro-optical device is improved. It becomes possible to make it.

  In the present embodiment described above, instead of providing the data line driving circuit 101 and the scanning line driving circuit 104 on the TFT array substrate 10 in the electro-optical device, for example, for driving mounted on a TAB (Tape Automated Bonding) substrate. The LSI may be electrically and mechanically connected to the external circuit connection terminal 102 via an anisotropic conductive film. Further, for example, a TN (Twisted Nematic) mode, a VA (Vertically Aligned) mode, a PDLC (Polymer Dispersed) are respectively provided on the side on which the projection light of the microlens array plate 20 is incident and 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 to 3 is used as the counter substrate, but such a 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.

  Further, FIG. 8 shows a configuration in which each microlens 500 is arranged so that the convexly protruding curved surface faces downward in FIG. 9, but as shown in FIG. You may make it arrange | position the curved surface which protruded the lens 500 convexly toward the upper side in the figure. FIG. 9 is a cross-sectional view similar to FIG. 8 showing the configuration of the microlens 500 in this case. In FIG. 9, the light shielding film 23 and the like are formed on the cover glass 200 in the same manner as in FIG.

<1-3: Manufacturing method of microlens array plate>
Next, a method for manufacturing the microlens array plate 20 according to the present embodiment will be described with reference to FIGS.

  10, FIG. 12 and FIG. 13 are process diagrams schematically showing the cross-sectional configuration of the microlens array plate 20 in each step of the manufacturing process.

  First, as shown in FIG. 10A, an amorphous silicon film is formed on the transparent substrate 210a as a mask 900 by, for example, CVD (Chemical Vapor Deposition). The mask 900 may be a Cr film having resistance to hydrofluoric acid, a polysilicon film, or the like.

  Subsequently, as shown in FIG. 10B, a plurality of openings are formed in a portion of the mask 900 corresponding to the position where the concave portion shown in FIG. 1B is formed, for example, by patterning the mask 900 using a photolithography method. A portion 902 is formed.

  Here, FIG. 11 is a diagram schematically showing the planar configuration of the mask 900, for explaining the positional relationship between the lens formation region 20a and each opening 902 and the shape of each opening 902. FIG. As shown in FIG. 11, in the mask 900, a plurality of openings 902 are formed in a region corresponding to the lens forming region 20a. Each opening 902 is formed to have a circular shape in a plan view and a size smaller than the concave portion 500a corresponding to the opening 902.

  Subsequently, in FIG. 10C, isotropic etching is performed on the transparent substrate 210a through a mask 900 in which a plurality of openings 902 are formed, thereby forming a plurality of recesses 500a. More specifically, the isotropic etching is preferably performed by wet etching using an etchant such as hydrofluoric acid. At this time, the planar shape of the concave portion 500a is a circle until the concave portions 500a adjacent to each other in the vertical and horizontal directions contact each other. If the wet etching is continued, the planar shape approaches a rectangular shape in which circles are connected. Further, when the concave portion 500a adjacent to each other comes into contact with each other, the planar shape of the concave portion 500a thereafter becomes a rectangular shape. Become. At any stage, the inner surface of the concave portion 500a forms a part of a spherical surface, and the curvature radius of the spherical surface increases as etching continues. The greater the curvature radius, the deeper the recess 500a. At this time, since the etching is not performed on the non-lens forming region, the height of the concave portion 500a including the edge thereof on the transparent substrate 210a is lower than that of the non-lens forming region. That is, as etching of the concave portion 500a proceeds, a planar shape in which the entire lens forming region 20a is recessed lower than the non-lens forming region is constructed on the surface of the transparent substrate 20a. Therefore, if the cover glass 200 is pasted on the non-lens forming area as it is, the manufactured microlens array plate is considerably thick.

  Note that isotropic etching is terminated by, for example, time management. As described above, the mask 900 is formed to extend from the lens formation region 20a to the non-lens formation region, so that it is possible to prevent the mask 900 from being damaged as the wet etching progresses. Further, isotropic etching may be performed by dry etching.

  Thereafter, in FIG. 10D, the mask layer 900 is removed by an etching process.

  Next, in FIG. 12A, a protective film 910 made of, for example, a resist as a protective material is formed continuously from each concave portion 500a to the concave portion 500a. Thereby, the protective film 910 is formed in the lens forming region 20a by the protective material filled in each of the recesses 500a, and is formed across the lens forming region 20a and the non-lens forming region.

  Subsequently, in FIG. 12B, the portion formed outside each recess 500a in the protective film 910 described above is removed, and the portion formed inside each recess 500a is left. As a result, the non-lens formation region is exposed from the protective film 910.

  Thereafter, in FIG. 12C, for example, a chemical mechanical polishing (CMP) process is performed on the transparent substrate 210a as a polishing process. By the polishing process, the protective film 910 is also polished in addition to the non-lens formation region in the transparent substrate 210a, and the edge of the plurality of recesses 500a is exposed. That is, when the non-lens forming region is polished to the height of the edge of the plurality of recesses 500a, the edges of the plurality of recesses 500a are exposed in a lattice shape. Thus, the depth of each recess 500a can be reduced by retreating the non-lens formation region on one surface of the transparent substrate 210a by the polishing process. Further, since the protective film 910 is formed, in the polishing process, the non-lens forming region can be retracted without changing the shape of the curved surface of the lens in each recess 500a, and dust adheres to the recess 500a. Can be prevented.

  Next, in FIG. 13A, after the polishing process, the protective film 910 is removed from each recess 500a, and in FIG. 13B, a thermosetting transparent adhesive 230a is applied to the surface of the transparent substrate 210. To do. The adhesive 230a is filled in each recess 500a. Subsequently, in FIG. 13C, the cover glass 200 is pressed against the transparent substrate 210 to cure the adhesive 230 a to form the adhesive layer 230. As a result, it is possible to form a plano-convex microlens 500 having a curved lens surface in the shape of the concave portion 500a and having a relatively large radius of curvature in each concave portion 500a. In particular, since the surface height of the non-lens formation region is lowered in the steps of FIGS. 12B to 12C, the thickness of the adhesive layer 230 can be reduced, and the microlens 500 has a thickness. It is formed as a thin lens. As a result, the microlens 500 having a large radius of curvature and the thin microlens array plate 20 can be manufactured.

  Note that the focal length of the microlens 500 is preferably adjusted by changing the thickness of the cover glass 200, and the thickness of the transparent substrate 210 is also adjusted in accordance with the adjustment.

<2: Second Embodiment>
A second embodiment according to the method for manufacturing a microlens of the present invention will be described. The second embodiment is different from the first embodiment in that an etching process is performed in the step of FIG. Therefore, the etching process will be described with reference to FIG. FIG. 14 is a process diagram showing processes corresponding to FIG. 12, similarly to FIG. In FIG. 14, common parts with the first embodiment are denoted by the same reference numerals, and redundant description is omitted.

  The transparent substrate 210a shown in FIG. 12B is etched by wet etching or dry etching, and the non-lens forming region is moved backward as shown in FIG. As the protective material constituting the protective film 910, a material having an etching rate substantially equal to or smaller than that of the transparent substrate 210a, that is, a material that is difficult to be etched is used. If the etching rate between the protective material and the transparent substrate 210a is substantially the same, the protective film 910 also moves backward in addition to the non-lens formation region in the transparent substrate 210a, as in the above-described polishing process. On the other hand, when the etching rate of the protective material is smaller than that of the transparent substrate 210a, the non-lens forming region can be retreated exclusively with little or substantially no etching of the protective film 910 in the lens forming region 20a.

  Therefore, according to the second embodiment, the recesses 500a are protected by the protective film 910, and etching is performed without changing the shape of the curved surface of the lens formed in the recesses 500a. Can be shallow. In addition, since the protective film 910 is formed, dust can be prevented from adhering in each of the recesses 500a during etching.

<3: Third embodiment>
A third embodiment according to the method for manufacturing a microlens of the present invention will be described. In the third embodiment, the steps described with reference to FIGS. 12 to 13 in the first embodiment are different. Therefore, differences from the first embodiment will be described with reference to FIG. FIG. 15 is a process diagram schematically showing the respective steps corresponding to FIG. In FIG. 15, common parts with the first embodiment are denoted by the same reference numerals, and redundant description is omitted.

  15A, the portion of the transparent substrate 210a shown in FIG. 10D that occupies the non-lens formation region is removed by cutting or polishing, for example, with a cutting device, a scribing device, etc., and occupies the lens formation region 20a. Only the other portion 210d remains. Therefore, as compared with the first or second embodiment, the depth of the concave portion 500a can be reduced more easily without changing the shape of the curved surface of the lens formed in each concave portion 500a.

  Thereafter, in FIG. 15 (b), the adhesive 230a is applied to the surface of the transparent substrate 210d by the same procedure as in the step of FIG. 13 (b). In FIG. 15 (c), the step of FIG. By the same procedure, the cover glass 200 is bonded to the transparent substrate 210d through the adhesive 230a to form the adhesive layer 230.

  Therefore, the microlens array plate manufactured according to the third embodiment removes the non-lens formation region from the microlens array plate 20 shown in FIGS. 1A and 1B, and only the lens formation region 20a remains. It becomes the composition made to do.

<4: 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. 16 is a schematic cross-sectional view of the projection type color display device.

  In FIG. 16, 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. 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.

FIG. 1A is a schematic perspective view of a microlens array plate, and FIG. 1B is a schematic perspective view showing the configuration of the A-A ′ cross section of FIG. FIG. 2A is a partially enlarged plan view showing an enlarged portion related to the microlens, FIG. 2B is a partially enlarged sectional view of the microlens array plate, and FIG. It is an expansion perspective view which shows roughly the three-dimensional shape of the lens surface of a micro lens. FIG. 3A is a diagram schematically illustrating the cross-sectional shape of the microlens, and FIG. 3B is a diagram schematically illustrating the cross-sectional shape of the microlens of the comparative example. 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 arrangement | positioning relationship of the light shielding film and microlens in a microlens array board. It is sectional drawing for demonstrating the function of each micro lens. It is sectional drawing for demonstrating arrangement | positioning of each micro lens. It is manufacturing process sectional drawing (the 1) which shows the manufacturing method of the micro lens array board which concerns on 1st Embodiment later on. It is a figure which shows the planar structure of a mask to an enemy roughly. FIG. 6 is a manufacturing process cross-sectional view (part 2) illustrating the manufacturing method of the microlens array plate according to the first embodiment in order. It is manufacturing process sectional drawing (the 3) which shows the manufacturing method of the micro lens array board which concerns on 1st Embodiment later on. It is a manufacturing process sectional view showing the manufacturing method of the micro lens array board concerning a 2nd embodiment. It is manufacturing process sectional drawing which shows the manufacturing method of the micro lens array board which concerns on 3rd 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 20a ... Lens formation area 200 ... Cover glass 210, 210a ... Transparent substrate 230 ... Adhesive layer 500 ... Micro lens 500a ... Concave part 910 ... Protective film

Claims (11)

Forming a plurality of concave portions each having a lens curved surface of a microlens in a lens forming region on one surface of the transparent substrate;
Forming a protective film by filling the plurality of recesses with a protective material, and
Polishing the one surface so that a non-lens forming region located around the lens forming region on the one surface is retracted together with the protective film;
Removing the protective film retracted by the polishing treatment, filling the plurality of recesses with a transparent adhesive having a refractive index larger than that of the transparent substrate, and forming the microlens;
And a step of adhering a cover substrate constituted by using a transparent plate-like member to the transparent substrate via the adhesive. The method of manufacturing a microlens according to claim 1, wherein the step of performing the polishing process is performed by a chemical mechanical polishing process. Forming a plurality of concave portions each having a lens curved surface of a microlens in a lens forming region on one surface of the transparent substrate;
Forming a protective film by filling the plurality of recesses with a protective material, and
Performing an etching process on the one surface so as to recede at least the non-lens forming region located around the lens forming region on the one surface;
Removing the protective film and filling the plurality of recesses with a transparent adhesive having a refractive index larger than that of the transparent substrate to form the microlens;
And a step of adhering a cover substrate constituted by using a transparent plate-like member to the transparent substrate via the adhesive. The method of manufacturing a microlens according to claim 3, wherein the step of retracting the non-lens forming region to be etched is performed by wet etching or dry etching. The step of forming the protective film is performed by removing a portion of the protective film continuously formed from the inside of each concave portion and outside the concave portion, and removing the portion formed outside the concave portion, and forming the inside of the concave portion. The method for producing a microlens according to any one of claims 1 to 4, wherein the portion thus formed is left. 6. The method of manufacturing a microlens according to claim 1, wherein an edge portion of each of the recesses is exposed by the polishing process or the etching process. In the step of forming the plurality of recesses, each recess has an inner surface forming a part of a spherical surface and has a rectangular planar shape and is formed adjacent to the other recesses on each side. method for producing a micro lens according to any one of claims 1 6, characterized. The step of forming the plurality of recesses includes:
On the transparent substrate, a mask having a plurality of openings each having a planar size smaller than the concave portion is formed across the non-lens forming region from the lens forming region in a region corresponding to the lens forming region. And a process of
Forming the plurality of recesses by performing isotropic etching on the transparent substrate through the plurality of openings;
Method for producing a micro lens according to any one of claims 1 to 7, characterized in that it comprises a step of removing the mask. Microlenses, characterized in that it is manufactured by the manufacturing method of a microlens according to any one of claims 1 to 8. An electro-optical device comprising: the microlens according to claim 9; a display electrode facing the microlens; and a wiring or an electronic element connected to the display electrode. An electronic apparatus comprising the electro-optical device according to claim 10 .

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