JP2007179077A - Electro-optical device and projector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To increase a light-shielding performance against incident light or returning light in the channel region or its adjacent region of a TFT in a pixel part by using a relatively simple structure in an electro-optical device. <P>SOLUTION: The electro-optical device has a liquid crystal layer (50) held between a pair of substrates and pixel electrodes (9a) arranged in a matrix on a TFT array substrate (10). A data line (6) is made of a light-shielding material and has a main wiring part (6a) which covers the channel region (1a') of the TFT and its adjacent region when the substrate is observed from a counter substrate (20) side, and a protruding part (6b) protruding from the main wiring part along a scanning line. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a technical field of a TFT active matrix driving type electro-optical device including a plurality of pixel electrodes arranged in a matrix and a plurality of thin film transistors (hereinafter referred to as TFTs as appropriate) for switching driving them. Belongs.

  In an electro-optical device of the TFT active matrix driving type, when incident light is irradiated to a channel region of a pixel switching TFT provided in each pixel, a current is generated by excitation by light, and the characteristics of the TFT change. In particular, in the case of an electro-optical device for a projector light valve, since the intensity of incident light is high, it is important to shield incident light from the TFT channel region and its peripheral region. Conventionally, the channel region and its peripheral region are shielded from light by a light shielding film that defines an opening region of each pixel provided on the counter substrate and a data line on the TFT array substrate. Furthermore, a light-shielding film made of a refractory metal, for example, may be provided at a position facing the pixel switching TFT on the TFT array substrate (that is, below the TFT). If a light-shielding film is also provided on the lower side of the TFT as described above, the back surface reflection from the TFT array substrate 10 side or a combination of a plurality of electro-optical devices via a prism or the like constitutes one optical system. Projection light penetrating through a prism or the like from another electro-optical device can be prevented from entering the TFT of the electro-optical device.

  On the other hand, in general, in this type of electro-optical device, the polarity of the potential applied to each pixel electrode is reversed according to a predetermined rule in order to prevent deterioration of the electro-optical material by applying a DC voltage and to prevent crosstalk and flicker in the display image. An inversion driving method is adopted. The 1H inversion driving method in which the pixel electrodes in the same row are driven with the same polarity potential and the potential polarity is inverted for each row in a frame or field period is relatively easy to control and enables high-quality image display. It is used as an inversion driving method.

  However, the various light shielding techniques described above have the following problems. That is, the normal data lines are arranged to extend in a stripe shape so as to intersect the scanning lines when seen in a plan view. For this reason, when the incident light intensity is very high as in the projector application described above, the incident light crosses the scanning line including the gate electrode facing the channel region having a certain width from the counter substrate side. Therefore, it is basically difficult to sufficiently shield the light with the data line extending. Further, the light shielding film provided on the counter substrate side and the channel region or the semiconductor layer are considerably separated from each other through, for example, a liquid crystal layer, an electrode, an interlayer insulating film, etc. The light shielding by the light shielding film on the counter substrate side with respect to the light incident on is not sufficient. Above all, the light shielding film for shielding incident light from the opposite substrate side, the data line, and the light shielding film for shielding the return light from the back surface are generally formed of a metal film due to the relationship with the high temperature process of the TFT. And has a certain degree of reflectivity. Therefore, even if the light shielding film is formed so as to shield the incident light to the channel region of the TFT and its peripheral region, the light that has actually entered the electro-optical device from the region without the light shielding film is reflected on the opposite side. After being reflected by the inner surface of the light shielding film, the reflected light or the multiple reflected light reflected by the inner surface of the light shielding film on the opposite side finally reaches the channel region of the TFT and its peripheral region, and the current due to the light Will be generated. As described above, according to the conventional light-shielding technology, there is a first problem in that the flicker or the like occurs due to the change in the transistor characteristics of the TFT, and the quality of the display image is degraded.

  On the other hand, the 1H inversion driving technique described above has the following problems. That is, when the potential of the image signal applied to the pixel electrodes adjacent to each other on the TFT array substrate has a reverse polarity as in the 1H inversion driving method, a lateral electric field is generated between the adjacent pixel electrodes. Therefore, an electro-optical material such as liquid crystal that is originally supposed to be driven by a vertical electric field in a direction perpendicular to the substrate causes reverse tilt due to the influence of the horizontal electric field and causes light leakage. As a result, the contrast ratio is lowered. On the other hand, it is possible to cover a region where a horizontal electric field is generated with a light-shielding film, but in this case, an opening region of the pixel is narrowed according to the size of the region where the horizontal electric field is generated. In particular, as the distance between pixel electrodes adjacent to each other decreases as the pixel pitch becomes finer, such a lateral electric field increases, so these problems become more serious as the definition of electro-optical devices increases. End up. As described above, according to the conventional 1H inversion driving technique, there is a second problem that the quality of the display image is deteriorated due to the generation of the lateral electric field.

  The present invention has been made in view of the above first problem, and the characteristics of the pixel switching TFT are changed even when used in an environment where the light intensity of incident light and return light is high using a relatively simple configuration. It is a first object to provide an electro-optical device of a TFT active matrix driving method that hardly occurs and can display a high-quality image.

  Furthermore, the present invention has been made in view of the second problem described above. By using a relatively simple configuration and reducing the malfunction of the electro-optic material due to a lateral electric field, the pixel has a high aperture ratio and a high contrast. It is a second object to provide an electro-optical device such as a TFT active matrix driving type liquid crystal device that can display bright and high-quality images.

  In order to solve the first problem, the first electro-optical device according to the present invention includes an electro-optical material sandwiched between a pair of first and second substrates, and is arranged in a matrix on the first substrate. A pixel electrode, a thin film transistor that drives the pixel electrode, and a data line and a scanning line that are connected to the thin film transistor and cross each other, and at least a channel region of a semiconductor layer that forms the thin film transistor includes the data region The data line is made of a light-shielding material, covers at least the channel region when viewed from the second substrate side, and intersects the scanning line. And a projecting portion projecting along the scanning line for each channel region.

  According to the first electro-optical device of the present invention, at least the channel region of the semiconductor layer constituting the thin film transistor connected to each pixel electrode is disposed in the plane region where the data line and the scanning line intersect. Here, the data line is made of a light-shielding material, and the main wiring portion of the data line covers at least the channel region when viewed from the second substrate side and extends in a direction intersecting with the scanning line. The protruding portion of the data line protrudes along the scanning line from a portion facing the channel region in the main wiring portion. Therefore, the channel region of the thin film transistor is covered with the main wiring portion and the protruding portion so as to be wide in both the direction along the scanning line and the direction along the data line when viewed from the second substrate side. As a result, the channel region can be shielded not only from the projection light incident perpendicularly to the first substrate but also from the oblique incident light, and the characteristic change in the thin film transistor due to incomplete light shielding Can be prevented.

  In particular, if such a data line at least partially defines the opening area of each pixel on the upper side of the thin film transistor on the first substrate, a grid pattern for defining the opening area of the pixel on the second substrate, It is also possible to configure so as not to provide a strip-shaped light shielding film. If the light shielding film is not provided on the second substrate in this way, it is not necessary to increase the width of the light shielding film on the second substrate in consideration of the shift when the two substrates are bonded together. This is advantageous in increasing the aperture ratio of each pixel.

  In one aspect of the first electro-optical device of the present invention, the scanning line is provided in a gap between pixel electrodes adjacent to each other in a direction intersecting the scanning line when seen in a plan view, and the protrusion is Projecting into the gap in plan view.

  According to this aspect, since the protruding portion protrudes into the gap between the pixel electrodes, the parasitic capacitance generated between the pixel electrode and the data line having the protruding portion can be reduced.

  Note that the edge of the scanning line may be slightly overlapped with the edge of the pixel electrode in plan view, and the edge of the protrusion may be slightly overlapped with the edge of the pixel electrode. In particular, from the viewpoint of preventing light leakage between adjacent pixel electrodes, it is preferable to slightly overlap the edge of the protruding portion with the edge of the pixel electrode.

  In another aspect of the first electro-optical device of the present invention, the scanning line is made of a polysilicon film, and the data line is made of a light-shielding conductive film containing metal.

  According to this aspect, the scanning line is made of a light-transmitting polysilicon film, but due to the presence of the main wiring portion and the protruding portion of the data line made of a light-shielding conductive film containing a metal such as an opaque aluminum film. Thus, it is possible to reliably prevent the incident light from entering through the scanning line obliquely and reaching the channel region in the plane region where the scanning line and the data line intersect.

  In another aspect of the first electro-optical device of the present invention, the data line covers a channel adjacent region of the semiconductor layer adjacent to the channel region in addition to the channel region.

  Accordingly, not only the channel region of the thin film transistor but also the channel adjacent region is wide in both the direction along the scanning line and the direction along the data line as viewed from the second substrate side, and is covered with the main wiring portion and the protruding portion. It will be. As a result, the characteristic change in the thin film transistor due to incomplete light shielding can be prevented.

  In this aspect, the thin film transistor may be a thin film transistor having an LDD structure or an offset structure, and the channel adjacent region may include an LDD region or an offset region.

  According to this structure, since the thin film transistor has an LDD structure or an offset structure, off current can be reduced and stable switching characteristics can be obtained. At this time, since the LDD region or the offset region is shielded from light by the main wiring portion and the protruding portion of the data line, generation of current in the LDD region or the offset region due to excitation by light can be suppressed.

  In order to solve the second problem, the second electro-optical device of the present invention is configured such that an electro-optical material is sandwiched between a pair of first and second substrates, and is arranged in a matrix on the first substrate. A pixel electrode, a thin film transistor that drives the pixel electrode, and a data line and a scanning line that are connected to the thin film transistor and intersect with each other, and a counter electrode that faces the pixel electrode on the second substrate The data line includes a main wiring portion extending in a direction intersecting the scanning line, and a protruding portion protruding from the main wiring portion along the scanning line, and a ground plane of the pixel electrode is The pixel electrode and the counter electrode are connected to the scanning line by being flattened on the main wiring portion compared to the protrusion and rising on the protrusion compared to the main wiring portion. For each pixel electrode group arranged along Rolling is driven.

  According to the second electro-optical device of the present invention, since there is a protruding portion that protrudes along the scanning line from the main wiring portion, the lower ground of the pixel electrode is raised on the protruding portion as compared with the main wiring portion. Yes. For this reason, in this raised portion, a vertical electric field that is generated between the pixel electrode and the counter electrode and is approximately inversely proportional to the distance between the two electrodes is relatively strengthened compared to the non-raised portion. On the other hand, the pixel electrode and the counter electrode are inverted and driven for each pixel electrode group arranged along the scanning line. That is, the 1H inversion driving described above is performed. Therefore, a horizontal electric field is generated in a gap region between adjacent pixel electrodes in a direction intersecting with the scanning line as viewed in a plan view. However, in the present invention, the gap region where the lateral electric field is generated is nothing but the region where the lower ground of the pixel electrode is raised as described above. Therefore, since the vertical electric field is strengthened in the region where the horizontal electric field is generated, the adverse effect of the horizontal electric field is attenuated by the strong vertical electric field in the electro-optical device that is supposed to be driven by the vertical electric field. Is possible. As a result, the malfunction of the electro-optic material due to the adverse effect of the transverse electric field is reduced.

  In addition, since the lower ground of the pixel electrode is flattened on the main wiring portion of the data line, the vertical electric field is not particularly strengthened in the gap region between the pixel electrodes adjacent to each other in the direction intersecting the data line. In this region, no lateral electric field is generated in the above-described 1H inversion driving. Therefore, in this region, there is no need to prevent adverse effects due to the transverse electric field. On the contrary, in this region, the operation failure of the electro-optical material generally caused by the level difference of the lower surface of the pixel electrode is reduced by flattening.

  As a result, it is possible to prevent a reduction in contrast ratio due to malfunction of the electro-optic material due to a lateral electric field or a step, and finally high-quality image display becomes possible.

  In one aspect of the second electro-optical device of the present invention, the protrusions are arranged so as to occupy more than half of the pixel electrodes adjacent to each other when seen in a plan view.

  According to this aspect, since the protruding portion is arranged so as to occupy most of the region occupied by the pixel electrodes, the vertical electric field is strengthened by the presence of the protruding portion in most of the regions where the lateral electric field is generated as described above. It becomes possible. However, since the operation cannot be performed if the adjacent data lines are short-circuited, the two protrusions in the same pixel electrode gap must be at least slightly separated from each other. In addition, for example, if a contact hole that electrically connects the pixel electrode and the thin film transistor intersects with the protruding portion, the operation becomes impossible. Therefore, when such a contact hole is opened, this should be avoided. The protrusion is arranged in a plane.

  In another aspect of the second electro-optical device of the present invention, the semiconductor device further includes an interlayer insulating film interposed between the first substrate, the semiconductor layer constituting the thin film transistor, and the layers constituting the scanning line and the data line. Further, at least one of the interlayer insulating film and the first substrate has a groove formed at a position facing the main wiring portion, and no groove is formed at a position opposed to the protruding portion. .

  According to this aspect, the pixel electrode on the main wiring portion is embedded in the trench formed in at least one of the interlayer insulating film and the first substrate directly or via the interlayer insulating film. The lower ground is flattened. Compared with this, since the protruding portion is not embedded in the groove, the lower ground of the pixel electrode on the protruding portion is relatively raised.

  In another aspect of the first or second electro-optical device of the present invention, a light shielding film is provided on the first substrate so as to cover at least the channel region when viewed from the first substrate side.

  According to this aspect, the light shielding film is provided at a position that covers at least the channel region of the thin film transistor when viewed from the first substrate side (that is, the lower side of the thin film transistor on the first substrate). Therefore, the channel region of the thin film transistor is shielded against the return light irradiated from the first substrate side by the light shielding film, and a change in characteristics due to light irradiation to the thin film transistor can be prevented.

  In this aspect, the light shielding film may be formed in a stripe shape along the scanning line.

  If comprised in this way, light shielding in a thin-film transistor will be performed with respect to the return light etc. from the 1st board | substrate side with a striped light shielding film. In this case, the light shielding film formed in a stripe shape along the scanning line can also be used as the wiring. Further, for example, by connecting the light shielding film to the outside of the image display area, it is connected to a constant potential wiring or a constant potential source. Accordingly, the light shielding film can be set to a constant potential relatively easily. In this way, when the light shielding film facing the channel region of the thin film transistor is set to a constant potential, it is possible to prevent a situation in which the potential fluctuation of the light shielding film adversely affects the characteristics of the thin film transistor. Alternatively, the light shielding film can function as a redundant wiring for other wiring.

  In this case, the light-shielding film may be formed in a lattice shape along the scanning line and the data line, and a strip-shaped light-shielding part that covers at least the channel region and extends along the scanning line. .

  According to this configuration, the light shielding region extending along the scanning line and the light shielding region extending along the data line can more reliably shield the return light from the first substrate side.

  In another aspect of the first or second electro-optical device of the present invention, the data line and the scanning line are arranged on the second substrate so as to overlap each other when viewed from the second substrate side. And further includes another light shielding film that at least partially defines an opening area of each pixel.

  According to this aspect, the other light shielding film that is disposed on the second substrate and defines the opening area of each pixel is provided at a position that at least partially overlaps the data line and the scanning line. Accordingly, the channel region is shielded against incident light by the light shielding film on the second substrate side and the data line on the first substrate side. Further, the opening area of each pixel is defined by the data line and the light shielding film on the second substrate side.

  In one aspect of the second electro-optical device of the present invention, the projecting portion is disposed so as to cover more than half of the scanning line when seen in a plan view.

  According to this aspect, since the projecting portion is arranged so as to occupy most of the region occupied by the scanning line portion between the pixel electrodes, the step of the scanning line is formed in most of the region where the lateral electric field is generated as described above. In addition, the presence of the protrusion can increase the vertical electric field. However, since the operation cannot be performed if the adjacent data lines are short-circuited, it is necessary to at least slightly separate the two protrusions superimposed on the scanning line portions in the same gap. In addition, for example, if a contact hole that electrically connects the pixel electrode and the thin film transistor intersects with the protruding portion, the operation becomes impossible. Therefore, when such a contact hole is opened, this should be avoided. The protrusion is arranged in a plane.

  In another aspect of the first or second electro-optical device of the present invention, the data line includes a low-reflection conductive film in the lower layer and a light-shielding conductive film in the upper layer.

  According to this aspect, the upper layer to which the incident light is irradiated is composed of the light-shielding conductive film, and the lower layer is composed of the low-reflection conductive film or the like in multiple layers, so that the incident light incident obliquely can be obtained. Since light can be absorbed by the protruding portion of the data line, it is possible to suppress as much as possible that the light reflected by the light shielding film or the like reaches the channel region 1a ′ and its adjacent region.

  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. In each of the embodiments described below, the electro-optical device of the present invention is applied to a liquid crystal device.

(First embodiment of electro-optical device)
A first embodiment of an electro-optical device according to the present invention will be described with reference to FIGS. 1 to 4, particularly focusing on a configuration in an image display region. Here, FIG. 1 is an equivalent circuit of various elements, wirings, and the like in a plurality of pixels formed in a matrix that forms an image display region of the electro-optical device. 2 is a plan view of a plurality of adjacent pixel groups of a TFT array substrate on which data lines, scanning lines, pixel electrodes, and the like are formed, and FIG. 3 is a cross-sectional view taken along line AA ′ of FIG. 4 is a cross-sectional view taken along the line BB ′ of FIG. In FIGS. 3 and 4, the scales of the layers and members are different for each layer and each member so that each layer and each member can be recognized on the drawings.

  In FIG. 1, TFTs 30 for controlling the pixel electrodes 9a are formed in a plurality of pixels formed in a matrix forming the image display area of the electro-optical device according to the present embodiment, and an image signal is supplied. The data line 6 is electrically connected to the source of the TFT 30. The 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 to each of a plurality of adjacent data lines 6 for each group. good. Further, the scanning line 3a is electrically connected to the gate of the TFT 30, and the scanning signals G1, G2,..., Gm are applied to the scanning line 3a in a pulse-sequential manner in this order at a predetermined timing. It is configured. 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 6 is obtained by closing the TFT 30 as a switching element for a certain period. Write at a predetermined timing. Image signals S1, S2,..., Sn written to the liquid crystal via the pixel electrode 9a are held for a certain period with a counter electrode (described later) formed on a counter substrate (described later). . The liquid crystal modulates light by changing the orientation and order of the molecular assembly according to the applied voltage level, thereby enabling gradation display. In the normally white mode, incident light cannot pass according to the applied voltage, and in the normally black mode, incident light can pass according to the applied voltage. Light having a contrast corresponding to the image signal is emitted from the optical device. Here, in order to prevent the held image signal from leaking, a storage capacitor 70 is added in parallel with the liquid crystal capacitor formed between the pixel electrode 9a and the counter electrode.

  In FIG. 2, a plurality of transparent pixel electrodes 9a (outlined by dotted line portions 9a ′) are provided in a matrix on the TFT array substrate of the electro-optical device. A data line 6, a scanning line 3a, and a capacitor line 3b are provided along the boundary. The data line 6 is electrically connected to a source region described later in the semiconductor layer 1a made of a polysilicon film or the like through the contact hole 5, and the pixel electrode 9a is connected to the semiconductor layer 1a through the contact hole 8. Among these, it is electrically connected to a drain region described later. In addition, the scanning line 3a is disposed so as to face the channel region 1a ′ (the hatched region in the lower right in the drawing) of the semiconductor layer 1a, and the scanning line 3a functions as a gate electrode. As described above, the TFT 30 in which the scanning line 3a is disposed as a gate electrode in the channel region 1a ′ is provided at each intersection of the scanning line 3a and the data line 6.

  The capacitor line 3b has a main line portion extending substantially linearly along the scanning line 3a, and a protruding portion protruding from the portion intersecting with the data line 6 to the front side (upward in the figure) along the data line 6. .

  A first light-shielding film 11a is provided so as to pass under the scanning line 3a and the TFT 30, respectively, in a region substantially overlapping with the scanning line 3a and the capacitor line 3b indicated by bold lines in the drawing. More specifically, in FIG. 2, the first light shielding film 11 a is formed in a stripe shape along the scanning line 3 a and the capacitor line 3 b, and a portion intersecting with the data line 6 protrudes downward. The channel region 1a ′ of each TFT 30 and the adjacent region thereof are provided so as to cover the channel region 1a ′ and the adjacent region of each TFT 30 when viewed from the TFT array substrate side by the wide portion including the protruding portion. Note that the first light shielding film 11a may be formed in a lattice shape extending along the scanning lines 3a and the data lines 6. Employing such a configuration is advantageous in that the light shielding property of the electro-optical device is further increased.

  In the present embodiment, in particular, the data line 6 shown by the diagonally slanting left line in FIG. 2 is a main wiring portion 6a extending in a direction orthogonal to the scanning line 3a, and a protrusion protruding from the main wiring portion 6a along the scanning line 3a. Part 6b. That is, in FIG. 2, the channel region 1 a ′ and its adjacent region have not only incident light perpendicularly incident on the substrate surface by the portion of the data line 6 that has the protruding portion 6 b and is formed wide. 2 is shielded against incident light that is incident obliquely from the top, bottom, left, and right in FIG. As described above, the data line 6 having the main wiring portion 6a and the protruding portion 6b is made of, for example, an existing metal thin film excellent in light-shielding property, extensibility and conductivity such as Al (aluminum). In this case, the data line 6 is obliquely incident by forming the upper layer irradiated with incident light with a light-shielding Al film and the lower layer with a low-reflection TiN (titanium nitride) film or the like. Since the light can be absorbed by the protruding portion 6b of the data line 6 with respect to the incident light, the light reflected by the first light-shielding film 11a and the like reaches the channel region 1a ′ and its adjacent region as much as possible. It can be suppressed. Note that the degree of protrusion of the protruding portion 6b (ie, the distance protruding from the main wiring portion 6a) depends on the device specifications such as the angle of incident light, the thickness of the liquid crystal layer, and the device performance such as the required contrast ratio and brightness. ) May be specifically set by experiment, experience, simulation, theoretical calculation, or the like.

  Next, as shown in FIGS. 3 and 4 as AA ′ sectional view and BB ′ sectional view in FIG. 2, respectively, the electro-optical device includes a TFT array substrate 10 constituting an example of a first substrate, And a counter substrate 20 that constitutes an example of a second substrate disposed to face the counter substrate. The TFT array substrate 10 is made of, for example, a quartz substrate, a glass substrate, or a silicon substrate, and the counter substrate 20 is made of, for example, a glass substrate or a quartz substrate. A pixel electrode 9a is provided on the TFT array substrate 10, and an alignment film 16 that has been subjected to a predetermined alignment process such as a rubbing process is provided above the pixel electrode 9a. The pixel electrode 9a is made of a transparent conductive film such as an ITO (Indium Tin Oxide) film. The alignment film 16 is made of an organic film such as a polyimide film.

  On the other hand, a counter electrode 21 is provided over the entire surface of the counter substrate 20, and an alignment film 22 subjected to a predetermined alignment process such as a rubbing process is provided below the counter electrode 21. The counter electrode 21 is made of a transparent conductive film such as an ITO film. The alignment film 22 is made of an organic film such as a polyimide film.

  The TFT array substrate 10 is provided with a pixel switching TFT 30 that controls switching of each pixel electrode 9a at a position adjacent to each pixel electrode 9a.

  The counter substrate 20 is provided with a second light shielding film 23 for defining at least a part of the opening region of each pixel. Therefore, it is possible to prevent incident light from entering the channel region 1a ′ of the semiconductor layer 1a of the pixel switching TFT 30 and the adjacent region from the side of the counter substrate 20 together with the data line 6 having the light shielding function as described above. . Furthermore, the second light-shielding film 23 has functions such as improving contrast and preventing color mixture of color materials when using a color filter. However, when priority is given to improving the brightness by increasing the aperture ratio of each pixel, the second light shielding on the counter substrate 20 is considered in consideration of a margin when the TFT array substrate 10 and the counter substrate 20 are bonded. It is advantageous to remove the membrane 23. In this case, it goes without saying that light shielding means is provided on the TFT array substrate 10. Further, a narrow second light shielding film 23 may be provided for the purpose of avoiding a temperature rise of the electro-optical device due to incident light.

  Liquid crystal is sealed in a space surrounded by a sealing material described later between the TFT array substrate 10 and the counter substrate 20 that are configured as described above and are arranged so that the pixel electrode 9a and the counter electrode 21 face each other. A liquid crystal layer 50 is formed. The liquid crystal layer 50 takes a predetermined alignment state by the alignment films 16 and 22 in a state where an electric field from the pixel electrode 9a is not applied. The liquid crystal layer 50 is made of, for example, a liquid crystal in which one kind or several kinds of nematic liquid crystals are mixed. The sealing material is an adhesive made of, for example, a photo-curing resin or a thermosetting resin for bonding the TFT array substrate 10 and the counter substrate 20 around them, and the distance between the two substrates is set to a predetermined value. Gap materials such as glass fibers or glass beads are mixed.

  Further, as shown in FIG. 3, a first light shielding film 11 a is provided between the TFT array substrate 10 and each pixel switching TFT 30 at a position facing each pixel switching TFT 30. The first light shielding film 11a is preferably at least one of Ti (titanium), Cr (chromium), W (tungsten), Ta (tantalum), Mo (molybdenum), and Pb (lead), which are preferably opaque high melting point metals. Including one metal, alloy, metal silicide, and the like. If comprised from such a material, the 1st light shielding film 11a will not be destroyed or melt | dissolved by the high temperature process in the formation process of the pixel switching TFT30 performed after the formation process of the 1st light shielding film 11a on the TFT array substrate 10 You can Since the first light shielding film 11a is formed, it is possible to prevent the return light from the TFT array substrate 10 from entering the channel region 1a ′ of the pixel switching TFT 30 and its adjacent region. The characteristics of the pixel switching TFT 30 are not changed by the generation of the photocurrent caused by the above.

  Further, as shown in FIGS. 3 and 4, a first interlayer insulating film 12 is provided between the first light shielding film 11 a and the plurality of pixel switching TFTs 30. The first interlayer insulating film 12 is provided to electrically insulate the semiconductor layer 1a constituting the pixel switching TFT 30 from the first light shielding film 11a. Further, the first interlayer insulating film 12 has a function as a base film for the pixel switching TFT 30 by being formed on the entire surface of the TFT array substrate 10. That is, the TFT array substrate 10 has a function of preventing changes in the characteristics of the pixel switching TFT 30 due to roughness during polishing of the surface of the TFT array substrate 10 and dirt remaining after cleaning. The first interlayer insulating film 12 is, for example, a highly insulating glass such as NSG (non-doped silicate glass), PSG (phosphorus silicate glass), BSG (boron silicate glass), BPSG (boron phosphorus silicate glass), or a silicon oxide film. It is made of a silicon nitride film or the like. The first interlayer insulating film 12 can also prevent the first light shielding film 11a from contaminating the pixel switching TFT 30 and the like.

  In the present embodiment, the insulating thin film 2 is extended from a position facing the scanning line 3a and used as a dielectric film, the semiconductor film 1a is extended to serve as the first storage capacitor electrode 1f, and the capacitor line facing these A storage capacitor 70 is configured by using a part of 3b as a second storage capacitor electrode. More specifically, the high-concentration drain region 1e of the semiconductor layer 1a extends below the data line 6 and the scanning line 3a, and an insulating thin film is formed on the capacitor line 3b extending along the data line 6 and the scanning line 3a. The first storage capacitor electrode 1f is disposed so as to be opposed to each other. In particular, the insulating thin film 2 as a dielectric of the storage capacitor 70 is nothing but the gate insulating film of the TFT 30 formed on the polysilicon film by high-temperature oxidation, and therefore can be made a thin and high withstand voltage insulating film. 70 can be configured as a large storage capacity with a relatively small area.

  In FIG. 3, the pixel switching TFT 30 has an LDD structure, and includes a scanning line 3a, a channel region 1a ′ of the semiconductor layer 1a in which a channel is formed by an electric field from the scanning line 3a, the scanning line 3a and the semiconductor layer. Insulating thin film 2 that insulates 1a, data line 6, low concentration source region 1b and low concentration drain region 1c of semiconductor layer 1a, high concentration source region 1d and high concentration drain region 1e of semiconductor layer 1a. A corresponding one of the plurality of pixel electrodes 9a is connected to the high concentration drain region 1e. The low-concentration source region 1b and the high-concentration source region 1d, and the low-concentration drain region 1c and the high-concentration drain region 1e are n-type having a predetermined concentration depending on whether an n-type or p-type channel is formed in the semiconductor layer 1a. Or by doping impurities for p-type. On the scanning line 3a, the insulating thin film 2, and the first interlayer insulating film 12, a second interlayer insulating film in which a contact hole 5 leading to the high concentration source region 1d and a contact hole 8 leading to the high concentration drain region 1e are respectively formed. 4 is formed. The data line 6 is electrically connected to the high concentration source region 1d through the contact hole 5. Further, on the data line 6 and the second interlayer insulating film 4, a third interlayer insulating film 7 in which a contact hole 8 to the high concentration drain region 1e is formed is formed. The pixel electrode 9a is electrically connected to the high concentration drain region 1e through the contact hole 8. The pixel electrode 9a is provided on the upper surface of the third interlayer insulating film 7 thus configured. The pixel electrode 9a and the high-concentration drain region 1e are electrically connected by relaying the same Al film as the data line 6 or the same polysilicon film as the scanning line 3b, or exclusively by relaying a relay conductive film. You may make it connect to.

  The pixel switching TFT 30 preferably has an LDD structure as described above, but may have an offset structure in which impurities are not implanted into the low concentration source region 1b and the low concentration drain region 1c, or one of the scanning lines 3a. It may be a self-aligned TFT in which impurity ions are implanted at a high concentration using a gate electrode as a mask as a mask to form high concentration source and drain regions in a self-aligning manner.

  Further, in this embodiment, a single gate structure in which only one gate electrode which is a part of the scanning line 3a of the pixel switching TFT 30 is arranged between the high concentration source region 1d and the high concentration drain region 1e is used. Two or more gate electrodes may be disposed on the substrate. At this time, the same signal is applied to each gate electrode. If the TFT is configured with dual gates or triple gates or more in this way, leakage current at the junction of the channel and the source and drain regions can be prevented, and the current at the time of off can be reduced. If at least one of these gate electrodes has an LDD structure or an offset structure, the off-current can be further reduced and a stable switching element can be obtained.

  As shown in FIGS. 2 to 4, in the first embodiment, in particular, the channel region 1a ′ of the semiconductor layer 1a constituting the TFT 30 and its adjacent region are arranged in the plane region where the data line 6 and the scanning line 3a intersect. Is done. Here, if it is assumed that the protruding portion 6b of the data line 6 does not exist, the scanning line 3a and the capacitor line 3b are made of a polysilicon film having a low light shielding property. Depending on the layer thickness of the liquid crystal layer 50, the light may enter the channel region 1a ′ and its adjacent region via the scanning line 3a and the capacitor line 3b. However, in the present invention, the presence of the protruding portion 6b extending from the data line 6 made of the light-shielding conductive film containing a light-shielding metal such as Al ensures the incident light incident obliquely in this way. Can be shielded from light. Further, since the first light shielding film 11a is provided at a position covering the channel region 1a ′ and the adjacent region of the TFT 30 when viewed from the lower side of the TFT 30, the channel region 1a ′ and the adjacent region are located on the TFT array substrate 10 side. For example, back light reflected from the back surface, for example, reflected light from the back surface or projection light from another electro-optical device that penetrates the combined optical system when a plurality of electro-optical devices are used in combination, is first. The light is shielded by the light shielding film 11a, and the characteristic change due to the return light of the TFT 30 can be prevented. Therefore, the light shielding for the channel region 1a ′ of the TFT 30 and the adjacent region is performed by the main wiring portion 6a and the protruding portion 6b of the light shielding data line 6 and the second light shielding film 23 on the counter substrate 20 on the upper side in FIG. In FIG. 3, the lower side is formed by the first light-shielding film 11a. In other words, the light is reliably shielded by wrapping the channel region 1a ′ and its adjacent region from above and below. In addition, the situation in which multiple reflected light generated in the electro-optical device is incident on the channel region 1a ′ and its adjacent region can be effectively prevented.

  Further, as in this embodiment, if the opening area of each pixel is partially defined above the TFT 30 on the TFT array substrate 10 by the data line 6, the opening area of the pixel is defined on the counter substrate 20. It is advantageous to provide the second light-shielding film 23 having a lattice shape or a belt shape in a smaller area.

  In addition, in the present embodiment, the scanning line 3a is provided in a gap between the pixel electrodes 9a adjacent to each other in a direction intersecting with the scanning line 3a when seen in a plan view, and the protrusion 6b is seen in a plan view. It protrudes into this gap. Accordingly, the parasitic capacitance generated between the pixel electrode 9a and the protruding portion 6b can be reduced. As shown in FIG. 2, the edge of the scanning line 3a is slightly overlapped with the edge of the pixel electrode 9a in plan view, and the edge of the protruding portion 6b is slightly overlapped with the edge of the pixel electrode 9a. It has been. From the viewpoint of preventing light leakage between the adjacent pixel electrodes 9a, it is preferable to slightly overlap the edge of the protruding portion 6b with the edge of the pixel electrode 9a. Since the overlapping of the protruding portion 6a protruding from the data line 6 and the pixel electrode 9a in this way leads to the generation of parasitic capacitance between the data line 6 and the pixel electrode 9a, as far as the manufacturing margin allows, It is preferable to overlap slightly.

  In the present embodiment described above, the first light shielding film 11a may be electrically connected to a constant potential source. With this configuration, the potential fluctuation of the first light shielding film 11a does not adversely affect the pixel switching TFT 30 disposed opposite to the first light shielding film 11a. Further, by setting the capacitor line 3b to a constant potential, it can function well as the second storage capacitor electrode of the storage capacitor. In this case, as a constant potential source, a constant potential source such as a negative power source or a positive power source supplied to a peripheral circuit (for example, a scanning line driving circuit, a data line driving circuit, etc.) for driving the electro-optical device, grounding Examples thereof include a power source and a constant potential source supplied to the counter electrode 21.

  As described above in detail, according to the electro-optical device of this embodiment, since the light shielding function is high in the channel region 1a ′ of the TFT 30 in the pixel portion and its adjacent region, high-quality image display is possible due to good TFT characteristics. Moreover, since the pixel aperture ratio is hardly lowered by the light shielding film, bright image display is possible.

(Second embodiment of electro-optical device)
A second embodiment of the electro-optical device according to the present invention will be described with reference to FIGS. 5 to 7, particularly focusing on the configuration in the image display region. FIG. 5 is a plan view of a plurality of adjacent pixel groups on the TFT array substrate on which data lines, scanning lines, pixel electrodes, and the like are formed, and FIG. 6 is a cross-sectional view taken along line AA ′ of FIG. FIG. 7 is a schematic plan view of the pixel electrode showing the potential polarity and the region where the lateral electric field is generated in each electrode in the 1H inversion driving method. In addition, the BB ′ sectional view of FIG. 5 in the second embodiment is the same as that shown in FIG. 4 in the first embodiment. In the second embodiment shown in FIGS. 5 and 6, the same reference numerals are given to the same components as those in the first embodiment shown in FIGS. 1 to 4, and the description thereof is omitted. Further, in FIGS. 5 and 6, the scales are different for each layer and each member so that each layer and each member have a size that can be recognized on the drawings.

  As shown in FIGS. 5 and 6, in the second embodiment, the protruding portion 6b ′ of the data line 6 ′ has a region occupied by the adjacent pixel electrodes 9a and a region overlapping the scanning line 3a in plan view. However, they are arranged to occupy more than half of each. Furthermore, the electro-optical device according to the second embodiment is driven by the 1H inversion driving method in which the potential polarity applied to the liquid crystal layer 50 is inverted for each group of pixel electrodes 9a along the same scanning line 3a. About another structure, it is the same as that of 1st Embodiment.

  Here, with reference to FIG. 7, the relationship between the potential polarity of the adjacent pixel electrodes 9a and the lateral electric field generation region in the 1H inversion driving method employed in this embodiment will be described.

  That is, as shown in FIG. 7A, during the period in which the image signal of the nth (where n is a natural number) field or frame is displayed, the liquid crystal drive voltage indicated by + or − is displayed for each pixel electrode 9a. The polarity is not inverted, and the pixel electrode 9a is driven with the same polarity for each row. Thereafter, as shown in FIG. 7B, when displaying the image signal of the (n + 1) th field or one frame, the potential polarity of the liquid crystal driving voltage in each pixel electrode 9a is inverted, and this n + 1th field or one frame is displayed. During the period of displaying the image signal, the polarity of the liquid crystal driving voltage indicated by + or − is not inverted for each pixel electrode 9a, and the pixel electrode 9a is driven with the same polarity for each row. Then, the states shown in FIGS. 7A and 7B are repeated at a period of one field or one frame, and driving by the 1H inversion driving method in this embodiment is performed. As a result, according to the present embodiment, it is possible to display an image with reduced crosstalk and flicker while avoiding deterioration of the liquid crystal due to application of a DC voltage. The 1H inversion driving method is advantageous in that there is almost no crosstalk in the column direction compared to the 1S inversion driving method in which the potential polarity applied to the liquid crystal layer 50 is inverted for each pixel electrode 9a in the column direction. .

  As can be seen from FIGS. 7A and 7B, in the 1H inversion driving method, the lateral electric field generation region C1 is always near the gap between the pixel electrodes 9a adjacent to each other in the column direction (Y direction). .

  Therefore, as shown in FIGS. 5 and 6, in the present embodiment, the pixel electrode 9 a and the counter electrode are formed by forming the protruding portion 6 b of the data line 6 in the region where the lateral electric field is generated and raising the ground of the pixel electrode 9 a. The structure which shortens the distance between 21 compared with another area | region is employ | adopted. Thereby, the vertical electric field is relatively strengthened and the horizontal electric field is weakened, and the adverse effect of the horizontal electric field on the liquid crystal layer 50 is reduced.

  In particular, according to the second embodiment, the vertical electric field can be strengthened by the presence of the protrusion 6b in more than half of the region where the horizontal electric field is generated as described above. However, if the contact hole 8 that electrically connects the pixel electrode 9a and the TFT 30 intersects the protruding portion 6b, the operation cannot be performed. Therefore, when the contact hole 8 is opened, this is avoided. Thus, the protruding portion 6b is arranged in a plane. In addition, since the lower ground of the pixel electrode 9a is flattened on the main wiring portion 6a of the data line 6, in general, the liquid crystal alignment defect caused by the step of the lower ground of the pixel electrode 9a is reduced by the flattening. Yes.

  As a result of the above, according to the second embodiment, it is possible to prevent the contrast ratio from being lowered due to light leakage caused by liquid crystal alignment failure due to a lateral electric field or a step, and finally high-quality image display is possible. It becomes.

  In order to flatten the pixel electrode 9a along the main wiring portion 6a of the data line 6 in this way, the first interlayer insulating film 12, the second interlayer insulating film 4, the third interlayer insulating film 7, and the TFT array A groove is formed in at least one of the substrates 10 at a position facing the main wiring portion 6a, and a groove is not formed at a position facing the protruding portion 6b, and the main wiring portion 6a is embedded in the groove. What is necessary is just to comprise. By partially flattening in this way, a high contrast ratio can be realized.

(Overall configuration of electro-optical device)
The overall configuration of each embodiment of the electro-optical device configured as described above will be described with reference to FIGS. 8 is a plan view of the TFT array substrate 10 as viewed from the side of the counter substrate 20 together with the components formed thereon. FIG. It is H 'sectional drawing.

  In FIG. 8, a sealing material 52 is provided on the TFT array substrate 10 along the edge, and in parallel with the inner side, for example, as a frame made of the same or different material as the second light shielding film 23. A third light shielding film 53 is provided. In a region outside the sealing material 52, a data line driving circuit 101 that drives the data line 6 by supplying an image signal to the data line 6 at a predetermined timing and an external circuit connection terminal 102 extend along one side of the TFT array substrate 10. A scanning line driving circuit 104 that drives the scanning line 3a by supplying a scanning signal to the scanning line 3a at a predetermined timing is provided along two sides adjacent to the one side. Needless to say, if the delay of the scanning signal supplied to the scanning line 3a is not a problem, the scanning line driving circuit 104 may be provided on only one side. Further, the data line driving circuit 101 may be arranged on both sides along the side of the image display area. Further, on the remaining side of the TFT array substrate 10, a plurality of wirings 105 are provided for connecting between the scanning line driving circuits 104 provided on both sides of the image display area. Further, at least one corner portion of the counter substrate 20 is provided with a vertical conductive material 106 for electrical connection between the TFT array substrate 10 and the counter substrate 20. As shown in FIG. 9, the counter substrate 20 having substantially the same contour as the sealing material 52 shown in FIG. 8 is fixed to the TFT array substrate 10 by the sealing material 52. On the TFT array substrate 10, in addition to the data line driving circuit 101, the scanning line driving circuit 104, etc., a sampling circuit 103 for applying image signals to the plurality of data lines 6 at a predetermined timing, and a plurality of data A precharge circuit for supplying a precharge signal of a predetermined voltage level to the line 6 in advance of the image signal, an inspection circuit for inspecting quality, defects, etc. of the electro-optical device during manufacture or at the time of shipment are formed. May be.

  Since the electro-optical device in each of the embodiments described above is applied to a color display projector, three electro-optical devices are respectively used as RGB light valves, and each light valve is used for RGB color separation. Each color light separated through the dichroic mirror is incident as projection light. Therefore, in each embodiment, the counter substrate 20 is not provided with a color filter. However, an RGB color filter may be formed on the counter substrate 20 together with the protective film in a predetermined region facing the pixel electrode 9a where the second light shielding film 23 is not formed. Furthermore, a microlens may be formed on the counter substrate 20 so as to correspond to one pixel so as to improve the light collection efficiency of incident light. Furthermore, in order to improve the brightness, a dichroic filter that creates RGB colors using light interference is formed by depositing several layers of interference layers having different refractive indexes on the counter substrate 20. Also good.

  In the electro-optical device according to each of the embodiments described above, incident light is incident from the side of the counter substrate 20 as in the conventional case. However, since the first light shielding film 11a is provided, the light is incident from the side of the TFT array substrate 10. Incident light may be incident and emitted from the counter substrate 20 side. That is, even when the electro-optical device is attached to the projector in this way, it is possible to prevent light from entering the channel region of the pixel switching TFT 30 and its adjacent region, and display a high-quality image. . Further, by forming the first light shielding film 11a on the TFT array substrate 10, an AR coated polarizing plate or AR film is used to prevent reflection on the back side of the TFT array substrate 10, or the TFT array substrate 10 itself. It is not necessary to use a substrate that has been subjected to AR treatment. Therefore, according to each embodiment, the material cost can be reduced, and it is very advantageous that the yield is not lowered due to dust, scratches, etc. when the polarizing plate is attached. In addition, since the light resistance is excellent, even when a bright light source is used or polarization conversion is performed by a polarization beam splitter to improve light use efficiency, image quality degradation such as crosstalk due to light does not occur.

  In addition, the switching element provided in each pixel has been described as a normal stagger type or coplanar type polysilicon TFT, but other types of TFT such as an inverted stagger type TFT or an amorphous silicon TFT are also used. Each embodiment is effective.

  The present invention is not limited to each of 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. An optical device is also included in the technical scope of the present invention.

3 is an equivalent circuit of various elements, wirings, and the like provided in a plurality of matrix-like pixels constituting an image display area in an embodiment of an electro-optical device. 2 is a plan view of a plurality of pixel groups adjacent to each other on a TFT array substrate on which data lines, scanning lines, pixel electrodes and the like are formed in the first embodiment of the electro-optical device. FIG. It is AA 'sectional drawing of FIG. It is BB 'sectional drawing of FIG. 12 is a plan view of a plurality of pixel groups adjacent to each other on a TFT array substrate on which data lines, scanning lines, pixel electrodes and the like are formed in a second embodiment of the electro-optical device. FIG. It is AA 'sectional drawing of FIG. It is a schematic plan view of a pixel electrode showing a potential polarity and a region where a lateral electric field is generated in each electrode in the 1H inversion driving method used in the second embodiment. It is the top view which looked at the TFT array board | substrate in embodiment of an electro-optical apparatus from the side of the opposing board | substrate with each component formed on it. It is HH 'sectional drawing of FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1a ... Semiconductor layer, 1a '... Channel region, 1b ... Low concentration source region, 1c ... Low concentration drain region, 1d ... High concentration source region, 1e ... High concentration drain region, 1f ... First storage capacitor electrode, 2 ... Insulation Thin film, 3a ... scanning line, 3b ... capacitance line, 4 ... second interlayer insulating film, 5 ... contact hole, 6 ... data line, 6a ... main wiring portion, 6b ... projecting portion, 7 ... third interlayer insulating film, 8 DESCRIPTION OF SYMBOLS Contact hole, 9a ... Pixel electrode, 10 ... TFT array substrate, 11a ... 1st light shielding film, 12 ... 1st interlayer insulation film, 16 ... Alignment film, 20 ... Counter substrate, 21 ... Counter electrode, 22 ... Alignment film, 23: Second light shielding film, 30: TFT, 50: Liquid crystal layer, 52: Sealing material, 53: Third light shielding film, 70: Storage capacitor, 101: Data line driving circuit, 104: Scanning line driving time.

Claims (10)

An electro-optical device having a plurality of pixels arranged in a matrix, in which an electro-optical material is sandwiched between a pair of first and second substrates,
A pixel electrode provided corresponding to the pixel on the first substrate, a thin film transistor electrically connected to the pixel electrode, and a data line and a scan line electrically connected to the thin film transistor and intersecting each other And
The data line has a main wiring portion extending in a direction intersecting the scanning line, and a protruding portion protruding along the scanning line from the main wiring portion,
The lower ground of the pixel electrode is flattened on the main wiring portion compared to the protruding portion and raised on the protruding portion compared to the main wiring portion,
The electro-optical device, wherein the pixel is driven in an inverted manner for each pixel electrode group arranged along the scanning line.   2. The electro-optical device according to claim 1, wherein the projecting portion is disposed so as to occupy more than half of the pixel electrodes adjacent to each other when seen in a plan view. The semiconductor device further includes an interlayer insulating film interposed between each of the first substrate and the semiconductor layer constituting the thin film transistor, the layers constituting the scanning line and the data line,
At least one of the interlayer insulating film and the first substrate has a groove formed at a position facing the main wiring portion,
The electro-optical device according to claim 1, wherein the groove is not formed at a position facing the protruding portion.   4. The electro-optical device according to claim 1, wherein a light shielding film is provided on the first substrate so as to cover at least the channel region when viewed from the first substrate side. 5. .   The electro-optical device according to claim 4, wherein the light shielding film is formed in a stripe shape along the scanning line.   The electro-optical device according to claim 4, wherein the light shielding film is formed in a lattice shape along the scanning lines and the data lines.   On the second substrate, another light-shielding is disposed at a position covering at least a part of the data lines and the scanning lines as viewed from the second substrate side, and at least partially defines an opening region of each pixel. The electro-optical device according to claim 1, further comprising a film.   The electro-optical device according to claim 1, wherein the protrusion is disposed so as to cover more than half of the scanning line when viewed in plan.   9. The electro-optical device according to claim 1, wherein the data line includes a low-reflection conductive film in a lower layer and a light-shielding conductive film in an upper layer.   A projector using the electro-optical device according to claim 1 as a light valve.

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