JP2010091960A - Electro-optical device and electronic equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To increase the quality of a displayed image in an electro-optical device such as a liquid crystal device without complicating the layout of a layered structure. <P>SOLUTION: The electro-optical device includes, on a substrate (10): a conductive layer (71) having recessed level differences (8) extending in a prescribed direction and constituting wiring lines and the like for an electro-optical operation; pixel electrodes (9) formed above the conductive layer and having level differences on the surface corresponding to the recessed level differences; and an alignment layer (16) formed above the pixel electrodes, the surface of which is subjected to rubbing treatment along a prescribed direction. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

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

  A liquid crystal device which is an example of this type of electro-optical device is configured by sandwiching a liquid crystal which is an example of an electro-optical material between a pair of substrates. An alignment film is formed on the surface of each substrate facing the liquid crystal in order to regulate liquid crystal molecules in a predetermined alignment state. In the case of an organic alignment film, the surface is often rubbed. In addition, in an element substrate on which a TFT or the like that functions as a switching element is formed, a pixel electrode for controlling the voltage of the liquid crystal alignment state is formed on the lower layer side of the alignment film.

  Here, since a typical pixel electrode is formed in an island shape for each pixel on a flat insulating film as a base, the thickness of the pixel electrode is between the surface of the pixel electrode and the surface of the insulating film. There is a difference in level. In this case, when an alignment film is formed so as to cover the pixel electrode and the surface of the alignment film is subjected to rubbing, the alignment film is laminated in the vicinity of the step when the rubbing cloth rubs up and down the step. Is larger or smaller, peels off or breaks, and the dust or rubbing wrinkles of the alignment film adheres to the surface of the alignment film or is mixed into the liquid crystal. As a result, there is a technical problem that the quality of the display image is deteriorated, such as a decrease in the transmittance of the liquid crystal device or a liquid crystal alignment failure. With respect to this problem, Patent Document 1 reduces the peeling or breakage of the alignment film due to the rubbing process by forming wirings, elements, and the like so as to flatten the step on the insulating film that is the base of the alignment film. The technique of doing is disclosed.

JP-A-7-168168

  However, according to the above-described background art, since it is necessary to form wirings, elements, and the like in the steps on the base of the alignment film, the layout of the laminated structure on the substrate is significantly limited. For example, technical difficulty in adding an additional capacitor to suppress pushdown of the image signal potential applied to the data line or adding a light shielding film to more effectively reduce the light leakage current of the TFT Accompanied by. In addition, there is a technical difficulty that it is difficult to form wiring and elements in such a very limited region in a minute and accurate manner.

  The present invention has been made in view of the above problems, for example, and includes an electro-optical device capable of displaying a high-quality image without complicating the layout of the laminated structure, and such an electro-optical device. It is an object to provide an electronic device.

  In order to solve the above-described problems, an electro-optical device according to the present invention has a concave step extending on a surface on a substrate, and has wiring, electrodes, and electrons for performing an electro-optical operation in a pixel region. A conductive layer constituting at least a part of the element; and a plurality of pixel electrodes formed on an upper layer side of the conductive layer, the surface having a step corresponding to the concave step, and arranged in the pixel region; And an alignment film which is formed on the upper layer side of the pixel electrode and whose surface is rubbed along the predetermined direction.

  The electro-optical device according to the present invention includes, for example, an electro-optical material such as liquid crystal sandwiched between a pair of substrates, and performs an electro-optical operation such as displaying an image by regulating the alignment state of the liquid crystal. .

  On one substrate, for example, electronic elements such as scanning lines and data lines and pixel switching TFTs are laminated as necessary while being insulated from each other via an insulating film, and on the upper layer side A circuit for driving the formed pixel electrode is configured. The pixel electrode is formed from a transparent conductive film such as an ITO film. During the operation of the electro-optical device, for example, the switching operation of the pixel switching TFT is controlled through the scanning line, and the image signal is supplied through the data line, and the voltage corresponding to the image signal is supplied to the pixel electrode through the TFT. Is applied. As a result, it is possible to display an image in a pixel region in which a plurality of pixel electrodes are arranged (also referred to as an “image display region”).

  The conductive layer is formed on a substrate from a transparent conductive material such as ITO, for example, and at least a part of wiring, electrodes, and electronic elements for performing an electro-optical operation in the pixel region (for example, data lines and capacitive electrodes) Configure. In addition, a concave step extending in a predetermined direction (that is, a rubbing direction described later) is formed on the surface of the conductive layer. That is, the surface of the conductive layer formed on the substrate has a predetermined direction which is oblique to the direction along the data line or the Y direction, the direction along the scanning line or the X direction, or the data line and the scanning line. A groove or a groove-like depression extending in the direction is formed. Here, the “predetermined direction” means a direction along a rubbing treatment direction (hereinafter referred to as a rubbing direction as appropriate) applied to the surface of the alignment film, which will be described later, or ideally the same direction as the rubbing direction. is there.

  The pixel electrode is formed on the upper layer side of the conductive layer and is disposed in a pixel region where electro-optical operation is performed. For example, a plurality of pixel electrodes are formed in an island shape for each pixel defined by data lines and scanning lines formed along different directions on the substrate. Here, since a concave step is present on the surface of the conductive layer formed on the lower layer side of the pixel electrode, a step corresponding to the concave step is formed on the surface of the pixel electrode. The step on the surface of the pixel electrode can be easily formed by, for example, laminating the pixel electrode via an interlayer insulating film above the conductive layer having a concave step on the surface.

  Further, an alignment film is formed on the upper layer side of the pixel electrode. The surface of the alignment film is rubbed along a predetermined direction in order to control the alignment state of the liquid crystal sandwiched between the substrates, for example. Here, if the surface of the pixel electrode has a flat shape without a concave step, the alignment film is peeled or damaged during the rubbing process as follows. For example, when the pixel electrode is formed on the base layer of the pixel electrode having a flat surface, a step is generated between the surface of the lower sustaining layer and the surface between the pixel electrodes. When an alignment film is formed on the pixel electrode and a rubbing process is performed, pressure is applied to the edge of the step, which causes peeling or breakage of the alignment film formed on the upper layer side of the pixel electrode. The alignment film is more likely to be peeled off or damaged because the pressure is more easily applied as the length of the edge of the step becomes longer, so that the length of the edge of the step becomes longer. As described above, if the surface of the pixel electrode is flat, the edge portion is naturally linear, so that pressure is easily applied, and the alignment film is likely to be peeled off or damaged. Note that the dust or rubbing wrinkles of the alignment film caused by peeling or breakage of the alignment film adheres to the vicinity of the step between the pixel electrode and the base layer, or is mixed into the liquid crystal injected between the substrates. This causes poor alignment and a decrease in transmittance, which causes a decrease in display image quality.

  On the other hand, in the present invention, since the recess is formed on the surface of the pixel electrode, the length of the edge of the recess is shortened. Therefore, the pressure applied during the rubbing process of the alignment film formed on the upper layer side is smaller than that in the case of the pixel electrode having no depression as described above. That is, by forming a dent on the surface of the pixel electrode as in the present invention, it is possible to prevent the alignment film formed on the upper layer side from being peeled off or damaged during the rubbing process.

  As described above, according to the present invention, by forming a concave step along the rubbing direction on the surface of the pixel electrode, peeling or breakage of the alignment film during the rubbing process can be prevented, and an electric material having a good alignment film can be obtained. An optical device can be realized. As a result, for example, dust such as fragments of the alignment film can be prevented from entering the liquid crystal sandwiched between the substrates, and dust can be prevented from accumulating on the alignment film. A high-quality image can be displayed.

  In one aspect of the electro-optical device of the present invention, a plurality of the concave steps are arranged in a region overlapping each of the pixel electrodes when viewed in plan on the substrate.

  According to this aspect, a plurality of concave steps are formed on the surface of the conductive layer along the rubbing direction. In particular, a plurality of concave steps are formed on the surface of each pixel electrode, that is, for each pixel. By providing a plurality of concave steps as described above, the length of the edge of the pixel electrode, which is a place where pressure is easily applied during the rubbing process, can be shortened, so that peeling or breakage of the alignment film is more effective. Can be prevented. In order to more effectively prevent the peeling or breakage of the alignment film, it is preferable to provide as many concave steps as possible, but in reality, it is necessary to perform an electro-optical operation in the pixel region formed by the conductive layer. An appropriate number of concave steps may be arranged in consideration of the influence of the types of wiring, electrodes and electronic elements and the surface shape of the pixel electrode on the alignment state of the liquid crystal.

  In another aspect of the electro-optical device of the present invention, the concave step is formed in one region overlapping the pixel electrode when viewed in plan on the substrate.

  In this aspect, the concave step formed on the surface of the conductive layer is formed in a region overlapping the pixel electrode, and is not formed in other regions (for example, a non-opening region between the pixel electrodes). Thus, if there is an area where no concave step is formed and the area does not have a pixel electrode for performing image display, even if dust of the alignment film is generated, the display of the electro-optical device There is little effect on the image. That is, if a concave step is formed at least in a region that overlaps the pixel electrode that is an opening region, it is possible to prevent the transmittance of the electro-optical device from being lowered due to adhesion of dust in the alignment film in the region. it can.

  In this aspect, the conductive layer in another region located around the one region may be formed to have a film thickness equal to the film thickness at the bottom of the concave step.

  When the conductive layer is formed in this way, the surface has a shape that rises in a convex shape along the rubbing direction between adjacent concave steps in the region overlapping the pixel electrode, and other regions ( That is, the bottom of the concave step and other regions) have a flat shape. When the surface of the conductive layer is formed in this way, a corresponding substantially similar shape is formed on the surface of the pixel electrode formed on the upper side of the conductive layer (that is, the pixel electrode also overlaps the pixel electrode). In the region, a region raised in a convex shape along the rubbing direction is formed). As a result, even if the alignment film is peeled off or broken when dust is generated when the rubbing process is performed, the dust can be discharged in other areas formed flat, so that the pixel which is the opening area It is possible to prevent dust from remaining in a region overlapping with the electrode. As a result, an electro-optical device having excellent transmittance can be realized.

  In another aspect of the electro-optical device according to the aspect of the invention, the conductive layer is divided into a plurality of conductive lines respectively extending in the predetermined direction.

  According to this aspect, for example, the depth of the concave step existing on the surface of the conductive layer can be realized by forming the same depth as the film thickness of the conductive layer. In other words, the conductive line may be formed as a raised convex region remaining between adjacent concave steps when the step on the recess on the surface of the conductive layer is deepened. A shallow concave step may be formed on the surface of each of the divided conductive lines.

  By forming the conductive layer so as to have a plurality of conductive lines in this manner, the length of the edge of the step, which is a place where pressure is easily applied during the rubbing process, can be formed shorter. As a result, since the alignment film is less likely to generate dust, the transmittance is high and high-quality image display is possible.

  When the conductive layer is connected to the data line and formed as a capacitor electrode constituting the storage capacitor in order to suppress pushdown of the image signal potential, the capacitance value of the storage capacitor depends on the area of the capacitor electrode. Therefore, if the conductive layer is divided into conductive lines as in this embodiment, the size of the capacitance value that can be formed becomes small. However, in reality, the capacitance value required for the hold-down capacitor for suppressing the push-down is a relatively small value, so that a sufficiently large capacitance value is ensured even when a conductive wire with a small area is used as the capacitance electrode. So that there is no real problem.

  In another aspect of the electro-optical device of the present invention, the conductive layer and the pixel electrode are disposed to face each other via a capacitor insulating film, thereby forming a storage capacitor.

  According to this aspect, by using the conductive layer and the pixel electrode as they are as a pair of capacitor electrodes, it is possible to additionally form a storage capacitor without complicating the laminated structure formed on the substrate. For example, a storage capacitor connected to a pixel electrode to which an image signal is supplied can be formed by supplying a fixed potential to a conductive layer formed on the lower layer side of the pixel electrode from a power supply line or the like. As a result, for example, the holding capacitance is added to the wiring capacitance of the wiring to which the image signal is applied, or the capacitance caused by the overlap with other wiring, so that the potential that the original image signal should have varies. That is, it is possible to suppress the push-down of the image signal potential written to the pixel electrode. As a result, it is possible to reduce or prevent the occurrence of display unevenness along, for example, the data line due to the push-down of the image signal potential written to the pixel electrode.

  For example, if these conductive layers and pixel electrodes constituting the storage capacitor are formed from a transparent conductive material, a transmissive display is possible. For example, if formed from a light-reflective conductive material, a reflective display is possible. Is possible.

  Note that the capacitance value of the storage capacitor may be increased or decreased by appropriately adjusting the thickness of the dielectric film formed between the conductive layer and the pixel electrode and the area of the opposing capacitor electrode.

  In addition, since it is not necessary to separately add a conductive layer for the capacitor electrode in order to form the storage capacitor, the stacked structure does not have to be complicated. As a result, the manufacturing cost of the electro-optical device can be reduced and the overall size of the electro-optical device can be reduced, and a high-definition electro-optical device can be realized.

  In another aspect of the electro-optical device of the present invention, both the pixel electrode and the conductive layer include ITO (Indium Tin Oxide).

  According to this aspect, both the pixel electrode and the conductive layer are made of ITO. Since ITO is a transparent conductive material, it can be used for a pixel electrode arranged for each pixel or a conductive layer formed on the lower layer side of the pixel electrode without reducing the transmittance of the electro-optical device. Good signal transmission can be realized. That is, a transmissive display can be realized. Thus, by forming the pixel electrode and the conductive layer from ITO, an electro-optical device having high transmittance and capable of displaying a high-quality image can be realized.

  In addition, since ITO has a relatively large resistance value compared to a metal material such as aluminum, the conductive layer formed of ITO in this embodiment is preferably formed as an element that does not require high-speed operation. . Therefore, for example, it may be formed as a capacitor electrode to which a fixed potential as described above is applied.

  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).

  According to the electronic apparatus of the present invention, since it includes the electro-optical device of the present invention described above, a projection display device, a television, a mobile phone, an electronic notebook, a word processor, capable of performing high-quality image display, Various electronic devices such as a viewfinder type or a monitor direct-view type video tape recorder, a workstation, a videophone, a POS terminal, and a touch panel can be realized. 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 Conduction Electron-Emitter Display), and a display device using these electrophoretic device and electron emission device Is also possible.

  The operation and other advantages of the present invention will become apparent from the best mode for carrying out the invention described below.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following embodiments, a driving circuit built-in type TFT active matrix driving type liquid crystal device, which is an example of the electro-optical device of the present invention, is taken as an example.

<Liquid crystal device>
First, the overall configuration of the liquid crystal device according to the present embodiment will be described with reference to FIGS. 1 and 2.

  FIG. 1 is a schematic plan view showing a configuration of a liquid crystal device when the TFT array substrate 10 is viewed from the counter substrate 20 side together with the components formed thereon. 2 is a cross-sectional view taken along the line H-H 'in FIG.

  1 and 2, the liquid crystal device according to the present embodiment includes a TFT array substrate 10 and a counter substrate 20 that are arranged to face each other. The TFT array substrate 10 is, for example, a transparent substrate such as a quartz substrate or a glass substrate, or a silicon substrate. The counter substrate 20 is also a substrate made of the same material as the TFT array substrate 10, for example. A liquid crystal layer 50 is sealed between the TFT array substrate 10 and the counter substrate 20, and the TFT array substrate 10 and the counter substrate 20 are sealed around the image display region 10a where the electro-optical operation is performed. They are bonded to each other by a sealing material 52 provided in the region.

  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, for example, in the sealing material 52, a gap material 56 such as a glass fiber or a glass bead for dispersing the distance (inter-substrate gap) between the TFT array substrate 10 and the counter substrate 20 to a predetermined value is dispersed.

  A light-shielding frame light-shielding film 53 that defines the frame area of the image display area 10a is provided on the counter substrate 20 side in parallel with the inside of the seal area 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.

  A data line driving circuit 101, a sampling circuit 7, a scanning line driving circuit 104, and an external circuit connection terminal 102 are formed in the peripheral area located around the image display area 10 a on the TFT array substrate 10.

  In the peripheral region on the TFT array substrate 10, a data line driving circuit 101 and a plurality of external circuit connection terminals 102 are provided along one side of the TFT array substrate 10 on the outer peripheral side of the seal region.

  Further, a region located on the inner side of the seal region in the peripheral region on the TFT array substrate 10 is covered with the frame light shielding film 53 along one side of the image display region 10 a along one side of the TFT array substrate 10. A sampling circuit 7 is arranged.

  The scanning line driving circuit 104 is provided along two sides adjacent to one side of the TFT array substrate 10 so as to be covered with the frame light shielding film 53. Further, in order to electrically connect the two scanning line driving circuits 104 provided on both sides of the image display region 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 the peripheral region on the TFT array substrate 10, vertical conduction terminals 106 are disposed in regions facing the four corners of the counter substrate 20, and vertical conduction is provided between the TFT array substrate 10 and the counter substrate 20. A material is provided corresponding to the vertical conduction terminal 106 and electrically connected to the terminal 106.

  In FIG. 2, on the TFT array substrate 10, a laminated structure is formed in which wirings such as TFTs for pixel switching, scanning lines, and data lines are formed. In the image display area 10a, pixel electrodes 9 are provided in a matrix form on the upper layer of wiring such as pixel switching TFTs, scanning lines, and data lines. The pixel electrode 9 is formed as a transparent electrode made of an ITO film. An alignment film 16 is formed on the pixel electrode 9.

  On the other hand, a light shielding film 23 is formed on the surface of the counter substrate 20 facing the TFT array substrate 10. The light shielding film 23 is formed of, for example, a light shielding metal film or the like, and is patterned, for example, in a lattice shape in the image display region 10a on the counter substrate 20. On the light shielding film 23 (below the light shielding film 23 in FIG. 2), the counter electrode 21 made of an ITO film is formed, for example, in a solid shape so as to face the plurality of pixel electrodes 9, and further on the counter electrode 21 (FIG. 2, below the counter electrode 21), an alignment film 22 is formed.

  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. A liquid crystal storage capacitor is formed between the pixel electrode 9 and the counter electrode 21 by applying a voltage to each of the liquid crystal devices during driving.

  Although not shown here, on the TFT array substrate 10, in addition to the data line driving circuit 101 and the scanning line driving circuit 104, a plurality of data lines are precharged at a predetermined voltage level prior to the image signal. A precharge circuit to be supplied, an inspection circuit for inspecting the quality, defects, etc. of the liquid crystal device during manufacture or at the time of shipment may be formed.

  Next, the electrical configuration of the image display area 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 area of the liquid crystal device according to this embodiment.

In FIG. 3, a pixel electrode 9 and a pixel switching 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 9, and performs switching control of the pixel electrode 9 when the liquid crystal device according to the present embodiment operates. The data line 6 to which the image signal is supplied is electrically connected to the source region of the TFT 30. Image signals S1, S2,..., Sn to be written to the data lines 6 may be supplied line-sequentially in this order, or may be supplied for each group to a plurality of adjacent data lines 6. Good.

  The scanning line 11 is electrically connected to the gate of the TFT 30, and the liquid crystal device according to the present embodiment applies the scanning signals G1, G2,..., Gm to the scanning line 11 in a pulsed manner at a predetermined timing. It is configured to apply in a line sequential order. The pixel electrode 9 is electrically connected to the drain of the TFT 30, and the image signal S1, S2,..., Sn supplied from the data line 6 is obtained by closing the switch of the TFT 30 serving 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 9 is constant between the counter electrode 21 (see FIG. 2) formed on the counter substrate 20 (see FIG. 2). Hold for a period.

  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 electrically in parallel with the liquid crystal capacitor formed between the pixel electrode 9 and the counter electrode 21 (see FIG. 2). ing. One capacitor electrode 71 of the storage capacitor 70 is formed integrally with a capacitor line extending in the Y direction, and is shared between pixels arranged side by side in the Y direction. The capacitor electrodes 71 are electrically connected to each other in the peripheral region of the image display region 10a, and a predetermined potential, for example, a fixed potential or an alternating potential that is inverted at a constant cycle is supplied from the common potential line 300.

  Next, in the liquid crystal device according to the present embodiment, a specific stacked structure in the image display region 10a will be described in detail.

  FIG. 4 is a schematic diagram transparently illustrating the positional relationship between electrodes and wirings arranged for performing an electro-optical operation 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 TFT array substrate 10, scanning lines 11 and data lines 6 are arranged along the X direction and the Y direction, respectively. The TFTs 30 (that is, the semiconductor layers 30 a and A gate electrode 30b) is formed. The scanning line 11 is made of a light-shielding conductive material, for example, W (tungsten), Ti (titanium), TiN (titanium nitride) or the like, and is wider than the semiconductor layer a so as to include the semiconductor layer 30a of the TFT 30. Is formed. Here, as will be described later, since the scanning line 11 is arranged on the lower layer side than the semiconductor layer 30 a, the TFT array substrate 10 is formed by forming the scanning line 11 wider than the semiconductor layer 30 a of the TFT 30 in this way. The channel region 30b of the TFT 30 can be almost or completely shielded from the return light, such as the back-surface reflection of light and the light emitted from other liquid crystal devices by a multi-plate projector or the like and penetrating the composite optical system. As a result, the light leakage current in the TFT 30 is reduced during the operation of the liquid crystal device, the contrast ratio can be improved, and high-quality image display can be performed.

  The TFT 30 includes a semiconductor layer 30a and a gate electrode 30b. The semiconductor layer 30a is formed including a source region 30a1, a channel region 30a2, and a drain region 30a3. Here, an LDD (Lightly Doped Drain) region may be 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.

  The gate electrode 30b is formed through a gate insulating film in a region overlapping the channel region of the semiconductor layer 30a when viewed in plan on the TFT array substrate 10. Although not shown in FIG. 4, the gate electrode 30b is electrically connected to the scanning line 11 arranged on the lower layer side via the contact hole 34, and the TFT 30 is formed by applying a scanning signal. ON / OFF control.

  The source region 30 a 1 of the TFT 30 is electrically connected to the data line 6 through the contact hole 31. On the other hand, the drain region 30a3 is electrically connected to the pixel electrode 9 via a drain relay wiring (not shown in FIG. 4) formed in the contact hole 32.

  The pixel electrode 9 is formed in an island shape for each pixel. In the present embodiment, each pixel is divided into a matrix by the data lines 6 and the scanning lines 11. As shown by the dotted line in FIG. 4, the pixel electrode 9 is partially connected to the data line 6 and the scanning line 11 when the end portion of each pixel is viewed in plan on the TFT array substrate 10. It arrange | positions so that it may overlap.

  In the image display area of the liquid crystal device according to the present embodiment, a plurality of capacitor electrodes 71 formed along the Y direction are arranged. As shown in FIG. 4, a plurality of capacitor electrodes 71 are formed along the Y direction so as to pass through a region where the pixel electrode 9 is disposed in plan view. In the present embodiment, in particular, the capacitor electrodes 71 are formed so that the four capacitor electrodes 71 pass so as to overlap one pixel electrode 9. Each of the capacitor electrodes 71 extends over a plurality of pixel electrodes arranged in the Y direction, and is electrically connected to each other in the peripheral region of the image display region 10a (not shown in FIG. 4). Furthermore, these capacitive electrodes 71 are held at a predetermined potential by being electrically connected to the common potential line 300 (see FIG. 3) in the peripheral region. As will be described later, the capacitor electrode 71 forms a storage capacitor by sandwiching a capacitor insulating film between the capacitor electrode 71 and the pixel electrode 9 formed on the upper layer side.

  In FIG. 4, a part of the capacitor electrode 71 is omitted in order to clearly show wirings, elements, and the like formed on the TFT array substrate 10. In particular, FIG. 4 shows only the pixel electrode 9 drawn in the vicinity of the center of the pixel electrodes 9 for convenience of explanation, but in actuality, the capacitor electrode 71 is overlapped with all the pixel electrodes 9. It extends along the Y direction.

  Next, the laminated structure in the cross section taken along the line AA ′ of FIG. 4 will be described with reference to FIG. On the TFT array substrate 10, the scanning line 11 described above is formed wider than the semiconductor layer 30a of the TFT 30 formed on the upper layer side. The scanning line 11 is covered with a base insulating film 12, and the surface thereof is flattened. The underlying insulating film 12 also has a function of preventing changes in the characteristics of the TFT 30 for pixel switching due to roughness during the surface polishing of the TFT array substrate 10 and dirt remaining after cleaning.

  The TFT 30 includes a semiconductor layer 30a (source region 30a1, channel region 30a2, drain region 30a3), and a gate electrode 30b. In particular, the gate electrode 30 b is made of, for example, conductive polysilicon and is electrically connected to the scanning line 11.

  The data line 6 to which the image signal is supplied is electrically connected to the source region 30a1 through the contact hole 31 opened in the gate insulating film 13 and the first interlayer insulating film 14. On the other hand, the drain region 30 a 3 is electrically connected to the pixel electrode 9 formed on the upper layer side via the drain relay wiring 7. More specifically, the drain relay wiring 7 electrically connects the drain region 30 a 3 and the pixel electrode 9 through a contact hole 32 opened in the gate insulating film 13 and the first interlayer insulating film 14. The pixel electrode 9 a is electrically connected to the drain relay wiring 7 through a contact hole 33 opened in the second interlayer insulating film 15.

  A capacitor electrode 71 is formed on the lower layer side of the pixel electrode 9 with a capacitor insulating film 72 interposed therebetween. That is, the storage capacitor 70 is formed by sandwiching the capacitor insulating film 72 between the pixel electrode 9 and the capacitor electrode 71. By providing the storage capacitor 70 integrally with the pixel electrode 9 in this way, the voltage of the pixel electrode 9 can be held for a time that is, for example, three orders of magnitude longer than the time when the image signal is applied. As a result, the liquid crystal device having a high contrast ratio can be realized as a result of improving the holding characteristics of the liquid crystal element.

  Particularly in the present embodiment, both the pixel electrode 9 and the capacitor electrode 71 are made of ITO. Since ITO is a transparent conductive material, the transmittance of the liquid crystal device can be increased by using it for the pixel electrode disposed in the opening region of the image display region 10a and the capacitor electrode 71 formed on the lower layer side of the pixel electrode. An image signal can be transmitted satisfactorily without deteriorating, and a high-quality image display can be realized. Further, by forming the capacitor electrode 71 with the same material as the pixel electrode 9, the manufacturing process of the liquid crystal device can be simplified. Furthermore, it is also possible to prevent the occurrence of galvanic corrosion that occurs during production due to contact between conductive materials having different ionization tendencies.

  Since ITO has a relatively large resistance value compared to metal materials such as aluminum, it may cause a delay in the propagation of electrical signals when used in an element that requires high-speed operation. When used for the capacitor electrode 71 that does not require high-speed operation as in the embodiment, there is no such fear.

  An alignment film 16 is laminated on the pixel electrode 9 and the capacitor insulating film 72, and the surface of the alignment film, which is a surface in contact with the liquid crystal 50, is subjected to a rubbing process along a predetermined direction. In FIG. 4, for the sake of convenience, the surfaces of the pixel electrode 9 and the alignment film 16 are drawn flat, but in reality, grooves are provided along the rubbing direction. Such a detailed surface structure will be described in detail later.

  Next, with reference to FIG. 6, the laminated structure in the BB 'line cross section in FIG. 4 is demonstrated in detail.

  On the TFT array substrate 10, a base insulating film 12, a gate insulating film 13 and a first interlayer insulating film 14 are laminated, on which data lines 6 to which image signals are supplied, a drain region 30 a 3 and a pixel electrode 9. A drain relay wiring 7 for relay connection between them is arranged.

  Here, the storage capacitor 70 is formed on the second interlayer insulating film 15 as a pair of electrodes facing the capacitor electrode 71 and the pixel electrode 9 and the capacitor insulating film 72 is sandwiched therebetween. The capacitor electrode 71 that is one of the pair of electrodes is formed in an island shape on the second interlayer insulating film 15. That is, the capacitor electrode 71 in the present embodiment is formed as a plurality of conductive lines extending in the Y direction in FIG. Here, if the capacitor electrode 71 is divided into islands as shown in FIG. 6, the capacitance value of the storage capacitor 70 that can be formed becomes small. Even if it is used, a necessary and sufficient capacitance value can be ensured, so there is no problem.

  Here, detailed structures on the surfaces of the capacitor electrode 71, the pixel electrode 9, and the alignment film 16 will be described with reference to FIG. FIG. 7 is a schematic view conceptually extracting these components from the laminated structure on the TFT array substrate 10. In FIG. 7, in order to make each layer and each member have a size that can be recognized on the drawing, the scale is different for each layer and each member.

  First, as shown in FIG. 7A, an interlayer insulating film (that is, a base insulating film 12, a gate insulating film 13, and a first interlayer insulating film 14) is laminated on the TFT array substrate 10, and a plurality of layers are formed on the surface thereof. The capacitor electrode 71 is formed to extend in the Y direction. By forming a plurality of capacitor electrodes along the Y direction in this way, a step is formed between the interlayer insulating film, which is the base layer, and the surface of the capacitor electrode 71. That is, a concave step 8 is formed between adjacent capacitor electrodes 71. Here, the Y direction in which the concave step 8 extends coincides with the rubbing direction of the alignment film 16 formed on the upper layer side (that is, the direction of the arrow shown in FIG. 7).

  Subsequently, as shown in FIG. 7B, a capacitive insulating film 72 is laminated on the capacitive electrode 71. Here, a step along the rubbing direction corresponding to the concave step 8 is also formed on the surface of the formed capacitive insulating film 72.

  A pixel electrode 9 is further formed on the capacitor insulating film 72 as shown in FIG. A step along the rubbing direction is also formed on the surface of the pixel electrode 9 corresponding to the step formed on the surface of the capacitive insulating film 72 that is the underlying layer of the pixel electrode 9. As described above, when a step is provided on the surface of the pixel electrode 9, when the alignment film 16 is stacked on the upper layer side, the alignment film 16 near the step between the pixel electrode 9 and the base layer of the pixel electrode 9 is As described above, it is possible to prevent an excessive pressure from being applied during the rubbing process.

  Here, with reference to FIG. 8, the mechanism in which a pressure is applied with respect to an alignment film at the time of a rubbing process is demonstrated concretely. FIG. 8A is a schematic diagram illustrating a stacked structure near the end of the pixel electrode 9 of the liquid crystal device according to the present embodiment. FIG. 8B is a schematic diagram showing a stacked structure in the vicinity of an end portion of a pixel electrode of a liquid crystal device (hereinafter referred to as a comparative example) in which the capacitor electrode 71 is formed flat.

  First, as shown in FIG. 8B, in the comparative example in which the capacitor electrode 71 is formed flat, the capacitor insulating film 72 is formed on the upper layer side because the surface is formed flat. The surface of the pixel electrode 9 is also formed flat. That is, when the pixel electrode 9 is viewed from the front side in FIG. 8B, the upper edge of the pixel electrode 9 (that is, the line indicated by 9a in FIG. 8B) is a single linear shape. have. If an alignment film is formed on the pixel electrode 9 as shown in FIG. 8B and a rubbing process is performed, a large pressure is applied to the line portion indicated by 9a, and the alignment film is easily peeled off or damaged. That is, the ease of peeling or breakage of the alignment film formed on the upper layer increases in proportion to the length of the line indicated by 9a.

  On the other hand, in the liquid crystal device according to this embodiment, a recess is formed on the surface of the capacitive insulating film 72 as shown in FIG. 8A when viewed from the front side, the upper edge portion of the pixel electrode 9 (that is, the line indicated by 9a in FIG. 8A), but in the recessed area of the surface of the pixel electrode 9 (The corresponding edge is not included.) Is shorter than the case of FIG. That is, as the capacitor electrode 71 is formed on the lower layer side, the edge of the pixel electrode 9 is shortened by the amount of depression on the surface of the pixel electrode 9. Therefore, compared to the case of the comparative example, by providing a recess on the surface of the pixel electrode 9 as in the present embodiment, the length of the line 9a is shortened, so the alignment film formed on the upper layer side is more Hard to peel or break.

  As described above, according to the present embodiment, by forming the concave step 8 along the rubbing direction, the alignment film 16 is prevented from being peeled off or damaged during the rubbing process, and the liquid crystal device having the good alignment film 16 Can be realized. As a result, for example, dust such as broken pieces of the alignment film 16 can be prevented from entering the liquid crystal 50 sandwiched between the substrates, and dust can be prevented from accumulating on the alignment film 16. High and high-quality image display is possible.

<Modification>
FIG. 9 is a schematic diagram showing a stacked structure near the end of the pixel electrode 9 of the liquid crystal device according to this modification. In this modification, the capacitor electrode 71 forming the storage capacitor 70 which is the “conductive layer” in the present invention is not divided into a plurality of conductive lines, and is integrated so as to have a concave step on the surface. It differs from the previous embodiment in that it is formed. The laminated structure other than the capacitive electrode 71 is the same as in the above-described embodiment.

  By forming the capacitor electrode 71 in this way, the storage capacitor 70 having a larger capacitance value can be formed. Further, when the “conductive layer” of the present invention is provided as a shield electrode between the pixel electrode 9 and another conductive layer arranged on the lower layer side, it is integrated over a wide area as in this modification. Therefore, it is possible to form an excellent shield electrode because the electric field can be blocked well.

  Also in this modification, a step is formed on the surface of the pixel electrode 9 by forming the concave step 8 on the surface of the capacitor electrode 71. Therefore, as in the above-described embodiment, when the alignment film 16 is stacked on the upper layer side, excessive pressure is applied to the alignment film 16 near the step between the pixel electrode 9 and the underlying layer of the pixel electrode 9 during the rubbing process. Can be prevented from being applied.

<Electronic equipment>
Next, a specific example of an electronic apparatus to which the electro-optical device 100 according to this embodiment can be applied will be described with reference to FIG.

  First, an example in which the liquid crystal device 100 according to the present embodiment is applied to a display unit of a portable personal computer (so-called notebook personal computer) will be described. FIG. 10A is a perspective view showing the configuration of this personal computer. As shown in the figure, the personal computer 710 includes a main body 712 having a keyboard 711 and a display 713 to which the liquid crystal device 100 according to the present embodiment is applied as a panel.

  The liquid crystal device 100 according to the present embodiment is particularly preferably applied to a liquid crystal television or a display unit of a car navigation device. For example, by using the liquid crystal device 100 according to the present embodiment in the display unit of the car navigation device, a map image is displayed for an observer in the driver's seat, and an observer in the passenger seat is displayed. It is possible to display images such as movies.

  Next, an example in which the liquid crystal device 100 according to the present embodiment is applied to a display unit of a mobile phone will be described. FIG. 10B is a perspective view showing the configuration of this mobile phone. As shown in the figure, the mobile phone 720 includes a plurality of operation buttons 721, a receiver 722, a transmitter 723, and a display unit 724 to which the liquid crystal device 100 according to the present embodiment is applied.

  In addition to the personal computer shown in FIG. 10A and the mobile phone shown in FIG. 10B, electronic devices to which the liquid crystal device 100 according to this embodiment can be applied include a liquid crystal television and a viewfinder. Type / monitor direct-view type video tape recorder, car navigation device, pager, electronic notebook, calculator, word processor, workstation, videophone, POS terminal, digital still camera, etc.

  Note that the above-described color filter substrate, electro-optical device, and the like are not limited to the above-described examples, and it is needless to say that various modifications can be made without departing from the scope of the present invention.

  In the embodiments described above, the liquid crystal display panel is exemplified, but the electro-optical device of the present invention is similarly applied to an electrophoretic device such as electronic paper, and further to an EL (electroluminescence) device. It is possible.

  The present invention is not limited to the above-described embodiment, and can be appropriately changed without departing from the spirit or idea of the invention that can be read from the claims and the entire specification. An electro-optical device and an electronic apparatus including the electro-optical device are also included in the technical scope of the present invention.

1 is a plan view of a liquid crystal device according to a first embodiment. It is HH 'sectional drawing of FIG. It is a circuit diagram which shows the electrical structure of the liquid crystal device which concerns on this embodiment. It is a schematic diagram which shows transparently the positional relationship of wiring etc. in the image display area 10a of the liquid crystal device which concerns on this embodiment. It is AA 'sectional drawing of FIG. It is BB 'sectional drawing of FIG. It is sectional drawing which shows the laminated structure of the pixel electrode periphery of the liquid crystal device which concerns on this embodiment in detail. FIG. 2 is a schematic diagram illustrating in detail a peripheral structure of an end portion of a pixel electrode in a liquid crystal device according to the present embodiment and a typical liquid crystal device. It is a schematic diagram which shows in detail the peripheral structure of the edge part of the pixel electrode in the liquid crystal device which concerns on a modification. It is an example of an electronic apparatus to which the electro-optical device of the present embodiment is applied.

Explanation of symbols

  6 data lines, 9 pixel electrodes, 10 TFT array substrate, 10a image display area, 11 scanning line, 12 base insulating film, 16 alignment film, 20 counter substrate, 21 counter electrode, 30 TFT, 30a semiconductor layer, 30a1 source area, 30a2 channel region, 30a3 drain region, 30b gate electrode, 50 liquid crystal, 70 storage capacitor, 71 capacitor electrode, 72 capacitor insulating film

Claims (8)

On the board
A conductive layer having a concave step extending in a predetermined direction on the surface and constituting at least part of wiring, electrodes and electronic elements for performing an electro-optic operation in the pixel region;
A plurality of pixel electrodes formed on an upper layer side of the conductive layer, having a step corresponding to the concave step on the surface, and arranged in the pixel region;
An electro-optical device comprising: an alignment film formed on an upper layer side than the pixel electrode, and having a surface subjected to a rubbing process along the predetermined direction.   The electro-optical device according to claim 1, wherein a plurality of the concave steps are arranged in a region overlapping each of the pixel electrodes when viewed in plan on the substrate.   3. The electro-optical device according to claim 1, wherein the concave step is formed in one region overlapping the pixel electrode when viewed in plan on the substrate.   The film thickness of the said conductive layer in the other area | region located around the said 1 area | region is formed so that it may become equal to the film thickness in the bottom part of the said concave-shaped level | step difference. Electro-optic device.   5. The electro-optical device according to claim 1, wherein the conductive layer is divided into a plurality of conductive lines respectively extending in the predetermined direction.   6. The electro-optical device according to claim 1, wherein the conductive layer and the pixel electrode are disposed to face each other with a capacitive insulating film therebetween, thereby forming a storage capacitor.   The electro-optical device according to claim 1, wherein both the pixel electrode and the conductive layer contain ITO (Indium Tin Oxide).   An electronic apparatus comprising the electro-optical device according to claim 1.

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