JP2011186285A - Electrooptic device and method for manufacturing the same, and electronic equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve quality of a display image by suppressing disclination in an electrooptic device such as a liquid crystal display device. <P>SOLUTION: The electrooptic device includes on a substrate (10) a base film (12) having a groove part (12a) formed along between adjacent pixels on the surface and a pixel electrode (9a) having a slope part (9a') on the surface by forming at least a part of the end part of the pixel electrode on the groove part. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an electro-optical device such as a liquid crystal device, a manufacturing method thereof, and a technical field of an electronic apparatus such as a liquid crystal projector including the electro-optical device.

  In a liquid crystal device which is an example of this type of electro-optical device, for example, by applying a driving voltage corresponding to a display image between a pixel electrode and a counter electrode provided on a pair of substrates holding liquid crystal, the electrodes Image alignment is performed by controlling the alignment state of the liquid crystal molecules sandwiched therebetween. The pixel electrode is formed in an island shape for each pixel, and different drive voltages are applied to each of the pixel electrodes. For this reason, a horizontal electric field (that is, an electric field parallel to the substrate surface or an oblique electric field including a component parallel to the substrate surface) is generated between adjacent pixel electrodes according to the potential difference, which causes alignment defects in liquid crystal molecules. It becomes. As described above, if there is a region where alignment failure occurs (that is, a domain region), it causes various problems such as a decrease in contrast of a display image. In order to deal with such a problem, Patent Document 1 discloses a technique in which the end surface of the pixel electrode is formed obliquely by forming the pixel electrode by oblique lamination to suppress the generation of a lateral electric field.

JP 2009-20335 A

  As shown in Patent Document 1 described above, forming the end surface of the pixel electrode obliquely is considered to contribute to the suppression of the lateral electric field. However, in Patent Document 1, the pixel electrode is formed by obliquely laminating conductive materials using a resist as a mask. When a pixel electrode is formed using such a technique, it is difficult to form a pixel electrode having a uniform shape over a wide area on the substrate (that is, the entire pixel area). There is. In addition, when the end surface of the pixel electrode is formed obliquely, it is difficult to control the angle, and there is a technical problem that the shape of the pixel electrode is likely to vary and a shape defect is likely to occur.

  The present invention has been made in view of the above-described problems, for example. An electro-optical device capable of displaying a high-quality image by suppressing disclination, a manufacturing method thereof, and an electronic apparatus including the electro-optical device It is an issue to provide.

  In order to solve the above-described problem, an electro-optical device according to the present invention is an electro-optical device that sandwiches vertically aligned liquid crystal between a pair of substrates, the data lines intersecting each other on one of the pair of substrates, and A scanning line, a base film having a groove formed on the surface between adjacent pixels among pixels corresponding to the intersection of the data line and the scanning line when viewed in plan on the substrate, and the lower layer It is formed for each pixel on the ground film, and at least a part of the end portion is formed on the groove portion, thereby providing a pixel electrode having an inclined portion on the surface.

  According to the electro-optical device of the present invention, for example, an image signal is controlled from a data line to a pixel electrode, and so-called active matrix system image display is possible. The image signal is supplied from the data line to the pixel electrode through the transistor at a predetermined timing by turning on or off a transistor electrically connected between the data line and the pixel electrode. The pixel electrode is a transparent electrode made of a transparent conductive material such as ITO (Indium Tin Oxide), for example, and is displayed on the substrate corresponding to the intersection of the data line and the scanning line provided to intersect each other on the substrate. For example, a plurality of areas are provided in a matrix form in the area to be the area.

  The pixel electrode according to the present invention has an inclined portion on the surface by forming at least a part of the end portion on the groove portion formed on the surface of the base film. The inclined portion is formed so as to correspond to the groove portion formed in the base film of the pixel electrode (that is, by being formed on the groove portion of the base film), and suppresses a lateral electric field generated between the pixel electrodes.

  The groove existing on the surface of the base film can be formed with relatively high accuracy, for example, by etching or the like. Therefore, the angle of the inclined portion of the pixel electrode formed on the upper layer side can also be formed with high accuracy. Therefore, the inclined part should be formed accurately and over a wide area so that the disclination can be effectively suppressed according to the type of vertically aligned liquid crystal and the shape and position of various elements constituting the pixel. Can do.

  In particular, the inclined portion of the pixel electrode is preferably formed in a portion located in the pretilt direction of the vertically aligned liquid crystal. In this case, it is possible to effectively provide an inclined portion at a position where the disclination is likely to occur based on the alignment direction of the vertically aligned liquid crystal, that is, at the end of the pixel electrode located in the pretilt direction of the vertically aligned liquid crystal. Generation of a horizontal electric field can be suppressed, and high-quality image display with less disclination can be realized.

  The present invention can also be applied to a reflective electro-optical device in which a pixel electrode is formed from a conductive material having light reflectivity.

  In order to solve the above problems, a method for manufacturing an electro-optical device of the present invention includes a base film forming step for forming a base film on a substrate, a groove portion forming step for forming a groove portion on the surface of the base film, and the groove portion. After the formation step, the conductive layer is formed on the base film, and the conductive layer is patterned so that at least a part of the end portion is formed on the groove portion, thereby inclining the surface. A pixel electrode forming step of forming a pixel electrode having a portion.

  According to the present invention, the above-described electro-optical device (including various aspects) can be suitably manufactured.

  According to the electronic apparatus of the present invention, since the electro-optical device of the present invention described above is provided, a projection display device, a television set, a mobile phone, an electronic notebook, a portable audio player, which can display a high-quality image, Various electronic devices such as a word processor, a digital camera, a viewfinder type or a monitor direct-view type video tape recorder, a workstation, a videophone, a POS terminal, and a touch panel can be realized.

  The effect | action and other gain of this invention are clarified from the form for implementing demonstrated below.

It is the top view which looked at the liquid crystal device concerning this embodiment from the counter substrate side with each component formed on a TFT array substrate. It is the HH 'sectional view taken on the line of FIG. FIG. 4 is an equivalent circuit diagram of various elements, wirings, and the like in a plurality of pixels constituting an image display region of the liquid crystal device according to the present embodiment. It is a top view which shows the structure in the image display area of the liquid crystal device which concerns on this embodiment. FIG. 5 is a plan view schematically showing a detailed shape of a pixel electrode 9a extracted from FIG. FIG. 6 is a cross-sectional view taken along the line II ′ in FIG. 5. It is process sectional drawing which shows the manufacturing method of the liquid crystal device which concerns on this embodiment in process order. FIG. 4 is a plan view illustrating a configuration of a projector as an example of an electronic apparatus to which the electro-optical device according to the embodiment is applied.

<Electro-optical device>
First, an embodiment of an electro-optical device according to the invention will be described with reference to FIGS. 1 and 2. In the present embodiment, as an example of the electro-optical device, a liquid crystal device of an active matrix drive type with a built-in drive circuit is cited.

  The overall configuration of the liquid crystal device according to the present embodiment will be described with reference to FIGS. FIG. 1 is a plan view of a liquid crystal device according to an embodiment of the present invention as viewed from the side of a counter substrate together with each component formed on a TFT (Thin Film Transistor) array substrate. It is a HH 'sectional view taken on the line.

  1 and 2, in the liquid crystal device according to the present embodiment, a TFT array substrate 10 and a counter substrate 20 are arranged to face each other. The TFT array substrate 10 and the counter substrate 20 are made of a substrate such as a quartz substrate, a glass substrate, or a silicon substrate. The TFT array substrate 10 and the counter substrate 20 are an example of “a pair of substrates” according to the present invention.

  A liquid crystal layer 50, which is an example of “vertical alignment liquid crystal” according to the present invention, is provided between the TFT array substrate 10 and the counter substrate 20. The TFT array substrate 10 and the counter substrate 20 are bonded to each other by a sealing material 52 provided in a sealing region located around the image display region 10a.

  The sealing material 52 is made of, for example, an ultraviolet light curable resin for bonding the two substrates, and is applied on the TFT array substrate 10 in the manufacturing process and then cured by irradiation with ultraviolet light. In the sealing material 52, a gap material such as a glass fiber or a glass bead for setting a distance (that is, a gap) between the TFT array substrate 10 and the counter substrate 20 to a predetermined value may be dispersed. In this case, the gap material may be arranged in the image display region 10a or a peripheral region located around the image display region 10a in addition to or instead of the material mixed in the seal material 52.

  A data line driving circuit 101 and an external circuit connection terminal 102 are provided along one side of the TFT array substrate 10 in a region located outside the sealing region in which the sealing material 52 is disposed in the peripheral region. A sampling circuit 7 is provided on the inner side of the seal region along the one side. A scanning line driving circuit 104 is provided in the frame area inside the seal area along two sides adjacent to the one side.

  On the TFT array substrate 10, vertical conduction terminals 106 for connecting the two substrates with the vertical conduction material 107 are arranged in regions facing the four corner portions of the counter substrate 20. Thus, electrical conduction can be established between the TFT array substrate 10 and the counter substrate 20. Further, a lead wiring 90 for electrically connecting the external circuit connection terminal 102 to the data line driving circuit 101, the scanning line driving circuit 104, the vertical conduction terminal 106, and the like is formed.

  In FIG. 2, on the TFT array substrate 10, a laminated structure is formed in which pixel switching transistors as driving elements, wiring lines such as scanning lines and data lines are formed. Although the detailed structure of this laminated structure is not shown in FIG. 2, pixel electrodes 9a made of a transparent material such as ITO (Indium Tin Oxide) are provided on the laminated structure in a predetermined pattern for each pixel. It is formed in an island shape.

  The pixel electrode 9a is formed in the image display region 10a on the TFT array substrate 10 so as to face a counter electrode 21 described later. On the surface of the TFT array substrate 10 facing the liquid crystal layer 50, that is, on the pixel electrode 9a, an alignment film 16 is formed so as to cover the pixel electrode 9a.

  On the surface of the counter substrate 20 facing the TFT array substrate 10, a counter electrode 21 made of a transparent material such as ITO is formed so as to oppose the plurality of pixel electrodes 9a. A color filter may be formed on the counter substrate 20 in order to perform color display in the image display area 10a. An alignment film 22 is formed on the counter electrode 21 on the counter surface of the counter substrate 20.

  In addition to the data line driving circuit 101, the scanning line driving circuit 104, the sampling circuit 7, etc., a plurality of data lines are pre-set at a predetermined voltage level on the TFT array substrate 10 shown in FIGS. A precharge circuit for supplying a charge signal prior to an image signal, an inspection circuit for inspecting quality, defects, and the like of the liquid crystal device during manufacture or at the time of shipment may be formed.

  Next, an electrical configuration in the image display region 10a of the liquid crystal device according to the present embodiment will be described with reference to FIG. FIG. 3 is an equivalent circuit diagram of various elements, wirings, and the like in a plurality of pixels formed in a matrix forming the image display region 10a of the liquid crystal device according to this embodiment.

  In FIG. 3, a pixel electrode 9a and a TFT 30 are formed in each of a plurality of pixels formed in a matrix that forms the image display region 10a. The TFT 30 is electrically connected to the pixel electrode 9a, and performs switching control of the pixel electrode 9a during operation of the liquid crystal device. The data line 6a to which the image signal is supplied 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.

  The scanning line 11 is electrically connected to the gate of the TFT 30, and the liquid crystal device applies scanning signals G1, G2,..., Gm to the scanning line 11 in a pulse-sequential manner in this order at a predetermined timing. It is configured as follows. 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 TFT 30 as a switching element for a certain period. It is written at a predetermined timing. A predetermined level of image signals S1, S2,..., Sn written to the liquid crystal via the pixel electrode 9a is held for a certain period with the counter electrode formed on the counter substrate.

  The liquid crystal constituting the liquid crystal layer 50 (see FIG. 2) 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 transmittance for light is increased, and light having a contrast corresponding to an image signal is emitted from the liquid crystal 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 21 (see FIG. 2). The storage capacitor 70 is a capacitive element that functions as a storage capacitor that temporarily holds the potential of each pixel electrode 9a in response to supply of an image signal. One electrode of the storage capacitor 70 is connected to the drain of the TFT 30 in parallel with the pixel electrode 9a, and the other electrode is connected to the capacitor line 300 with a fixed potential so as to have a constant potential. According to the storage capacitor 70, the potential holding characteristic in the pixel electrode 9a is improved, and display characteristics such as contrast improvement and flicker reduction can be improved.

  Next, in the liquid crystal device according to the present embodiment, the positional relationship of electrodes and wirings arranged for performing an electro-optical operation in the image display region 10a will be described with reference to FIG. FIG. 4 is a plan view showing a configuration in the image display region 10a of the liquid crystal device according to the present embodiment. In FIG. 4, in order to make each layer and each member recognizable on the drawing, the scale is different for each layer and each member.

  On the image display area 10 a of the TFT array substrate 10, the scanning lines 11 and the data lines 6 a are arranged along the X direction and the Y direction, respectively, and the TFT 30 is formed near the intersection of the data lines 6 a and the scanning lines 11. Has been.

  The scanning line 11 is formed of a light-shielding conductive material, for example, W (tungsten), Ti (titanium), TiN (titanium nitride), or the like. The TFT 30 is formed wider than the semiconductor layer a so as to include the semiconductor layer 30a. The scanning line 11 is arranged on the lower layer side of the semiconductor layer 30a, and is formed wider than the semiconductor layer 30a constituting the TFT 30, so that it can be reflected on the back surface of the TFT array substrate 10 or other liquid crystal by a multi-plate projector or the like. The channel region 30b of the TFT 30 is arranged to be shielded almost or completely from the return light such as the light emitted from the apparatus and penetrating the synthesis optical system.

  The TFT 30 includes a semiconductor layer 30a and a gate electrode 30b. The semiconductor layer 30a includes a source region 30a1, a channel region 30a2, and a drain region 30a3. Note that a so-called LDD structure in which an LDD (Lightly Doped Drain) region is formed at the interface between the channel region 30a2 and the source region 30a1 or between the channel region 30a2 and the drain region 30a3 may be used.

  The gate electrode 30b is made of, for example, conductive polysilicon, and is electrically connected to the scanning line 11 through a contact hole 34 opened in the gate insulating film. Thus, the TFT 30 is controlled to be turned on / off by applying a scanning signal to the gate electrode 30b.

  The data line 6a is electrically connected to the source region 30a1 through the contact hole 31, and supplies an image signal to the source region 30a1. The drain region 30a3 is electrically connected to the relay layer 7 through the contact hole 32. The relay layer 7 is further connected to the pixel electrode 9 a through the contact hole 33. That is, the relay layer 7 applies a drive voltage corresponding to the image signal output from the drain region 30a3 of the TFT 30 to the pixel electrode 9a by relay-connecting the drain region 30a3 and the pixel electrode 9a.

  Here, the structure of the pixel electrode 9a will be described in more detail with reference to FIGS. FIG. 5 is a plan view schematically showing the detailed shape of the pixel electrode 9a extracted from FIG. 6 is a cross-sectional view taken along the line II ′ in FIG. In FIGS. 5 and 6, the scale of each layer / member is different for each layer / member so that each layer / member can be recognized on the drawing. In FIG. 6, for convenience of explanation, the laminated structure on the TFT array substrate 10 and the counter substrate 20 is appropriately omitted.

  The pixel electrode 9a is formed in a square shape when viewed in plan on the TFT array substrate 10. In the region surrounded by dotted lines 9a1 and 9a2 in FIG. 5, the inclined portion 9a ′ is formed by forming the surface obliquely along the end portion of the pixel electrode 9a.

  The interlayer insulating film 12 that is a base film of the pixel electrode 9a has a groove 12a on the surface. The interlayer insulating film 12 is an example of the “underlayer film” according to the present invention. The inclined portion 9a ′ of the pixel electrode 9a is formed so as to correspond to the groove portion 12a by forming the end portion of the pixel electrode 9a on the groove portion 12a. That is, the inclination angle of the inclined portion 9 a ′ can be adjusted by controlling the depth and angle of the groove portion 12 a on the surface of the interlayer insulating film 12.

  By providing the inclined portion 9a ′ at the end of the pixel electrode 9a, a lateral electric field generated between adjacent pixel electrodes 9a to which different drive voltages are applied can be suppressed (see the arrow shown in FIG. 6).

  In the present embodiment, the inclined portion 9a ′ is formed only in the portion of the end portion of the pixel electrode 9a that is located in the pretilt direction of the vertically aligned liquid crystal that constitutes the liquid crystal layer 50 (see the dotted arrow in FIG. 5). However, it may be provided along the end of the pixel electrode 9a (that is, along the outer periphery of the pixel electrode 9a).

<Manufacturing method>
Next, an embodiment of a method for manufacturing an electro-optical device according to the invention will be described with reference to FIG. FIG. 7 is a process cross-sectional view illustrating the manufacturing method of the liquid crystal device according to this embodiment in the order of processes.

As shown in FIG. 7A, for example, a substrate 10 such as a silicon substrate, a quartz substrate, or a glass substrate is prepared. Here, heat treatment is preferably performed at a high temperature of about 850 to 1300 ° C., more preferably 1000 ° C. in an inert gas atmosphere such as N ₂ (nitrogen), and distortion generated in the substrate 10 in a high-temperature process performed later is reduced. Pre-process as follows.

  On the TFT array substrate 10 processed in this way, a conductive layer and an insulating layer are appropriately patterned by etching or the like, thereby forming a laminated structure (for example, a data line, a scanning line, and a TFT). The laminated structure is not shown in FIG. 7 for convenience of explanation.

  Then, an interlayer insulating film 12 serving as a base film for the pixel electrode 9a is formed on the stacked structure thus formed.

  Subsequently, as shown in FIG. 7B, a resist (not shown) is formed on the interlayer insulating film 12 and patterned by etching or the like using the resist as a mask, so that a groove 12a is formed on the surface of the interlayer insulating film 12. Form. Note that the depth of the groove 12a is a factor that determines the angle of the inclined portion 9a 'provided at the end of the pixel electrode 9a to be formed later on the upper layer side. And the distance between the pixel electrodes 9a may be appropriately selected so that the disclination can be suitably suppressed.

  Subsequently, as shown in FIG. 7C, a conductive layer 9 is formed on the interlayer insulating film 12 having the groove 12a formed on the surface thereof. The conductive layer 9 is preferably formed of a conductive material. For example, a transparent conductive material such as ITO is used in the case of a transmissive liquid crystal device, and a conductive material having excellent light reflectivity such as aluminum in the case of a reflective liquid crystal device. It is recommended to use a functional material. Needless to say, the conductive layer 9 may be formed of a transparent conductive material such as ITO when the reflective liquid crystal device has a separate reflective layer.

  Subsequently, as shown in FIG. 7D, the conductive layer 9 formed on the interlayer insulating film 12 is patterned by etching into a pattern as shown in FIG. 5 to form a pixel electrode 9a. At this time, the patterning is performed so that the end of the pixel electrode 9 a is located on the groove 12 a of the interlayer insulating film 12 when viewed in plan on the TFT array substrate 10. As a result, a portion of the conductive layer 9 located in the groove 12a is formed as an inclined portion 9a 'and the surface is formed obliquely.

  An alignment film (not shown) is formed on the pixel electrode 9a, and the stacked structure on the TFT array substrate 10 is completed.

  Subsequently, as shown in FIG. 7E, the TFT array substrate 10 on which the laminated structure is formed is bonded to a counter substrate 20 prepared separately. A vertically aligned liquid crystal is sealed between the TFT array substrate 10 and the counter substrate 20 to form a liquid crystal layer 50, thereby completing the liquid crystal device according to this embodiment.

<Electronic equipment>
Next, a case where the above-described liquid crystal device is applied to a projector that is an example of an electronic device will be described with reference to FIG. The liquid crystal device described above is used as a light valve of a projector. FIG. 8 is a plan view showing a configuration example of the projector.

  As shown in FIG. 8, a projector 1100 includes a lamp unit 1102 made of a white light source such as a halogen lamp. The projection light emitted from the lamp unit 1102 is separated into three primary colors of RGB by four mirrors 1106 and two dichroic mirrors 1108 arranged in the light guide 1104, and serves as a light valve corresponding to each primary color. The light enters the liquid crystal panels 1110R, 1110B, and 1110G.

  The configurations of the liquid crystal panels 1110R, 1110B, and 1110G have the same configuration as that of the above-described liquid crystal device, and are driven by R, G, and B primary color signals supplied from the image signal processing circuit, respectively. The light modulated by these liquid crystal panels enters the dichroic prism 1112 from three directions. In this dichroic prism 1112, R and B light is refracted at 90 degrees, while G light travels straight. Accordingly, as a result of the synthesis of the images of the respective colors, a color image is projected onto the screen or the like via the projection lens 1114.

  Here, paying attention to the display images by the liquid crystal panels 1110R, 1110B, and 1110G, the display images by the liquid crystal panels 1110R and 1110B need to be horizontally reversed with respect to the display images by the liquid crystal panel 1110G.

  Since light corresponding to the primary colors R, G, and B is incident on the liquid crystal panels 1110R, 1110B, and 1110G by the dichroic mirror 1108, it is not necessary to provide a color filter.

  In addition to the electronic device described with reference to FIG. 8, a mobile personal computer, a mobile phone, a liquid crystal television, a viewfinder type or a monitor direct view type video tape recorder, a car navigation device, a pager, and an electronic notebook , Calculators, word processors, workstations, videophones, POS terminals, devices with touch panels, and the like. Needless to say, the present invention can be applied to these various electronic devices.

  The present invention is not limited to the above-described embodiments, and can be appropriately changed without departing from the spirit or concept of the invention that can be read from the claims and the entire specification. Electronic devices are also included in the technical scope of the present invention.

  DESCRIPTION OF SYMBOLS 9a ... Pixel electrode, 9a '... Inclination part, 10 ... TFT array substrate, 10a ... Image display area, 11 ... Scanning line, 12 ... Interlayer insulation film, 12a ... Groove part, 20 ... Counter substrate, 21 ... Counter electrode, 50 ... Liquid crystal layer

Claims (5)

An electro-optical device for sandwiching vertically aligned liquid crystal between a pair of substrates,
On one substrate of the pair of substrates,
Data lines and scan lines intersecting each other;
A base film having a groove formed on the surface between adjacent pixels among the pixels corresponding to the intersection of the data line and the scanning line when viewed in plan on the substrate;
An electro-optical device comprising: a pixel electrode formed on the base film for each of the pixels, and having at least a part of an end portion formed on the groove portion to have an inclined portion on a surface thereof. .   The electro-optical device according to claim 1, wherein the inclined portion is formed along a portion of the end portion of the pixel electrode that is positioned in a pretilt direction of the vertically aligned liquid crystal.   The electro-optical device according to claim 1, wherein the pixel electrode is made of a conductive material having light reflectivity. On the board
A base film forming step for forming the base film;
A groove forming step of forming a groove on the surface of the base film;
A conductive layer forming step of forming a conductive layer on the base film after the groove forming step;
And a pixel electrode forming step of forming a pixel electrode having an inclined portion on a surface thereof by patterning the conductive layer so that at least a part of the end portion is formed on the groove portion. Manufacturing method of optical device.   An electronic apparatus comprising the electro-optical device according to claim 1.

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