JP5428141B2 - Electro-optical device and electronic apparatus including the same - Google Patents

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.

  This type of electro-optical device includes a pixel electrode, a scanning line for selectively driving the pixel electrode, a data line, and a TFT (Thin Film Transistor) as a pixel switching element on a substrate, and is active. It is configured to be capable of matrix driving. In such an electro-optical device, a storage capacitor is generally provided between the TFT and the pixel electrode for the purpose of increasing the contrast.

  On the other hand, a liquid crystal device which is an example of the electro-optical device described above is frequently used not only as a direct-view display but also as a light modulation means (light valve) of a projection display device, for example. In particular, in the case of a projection display device, strong light from a light source is incident on a liquid crystal light valve, and this thin film transistor (TFT: Thin Film Transistor) in the liquid crystal light valve does not cause an increase in leakage current or malfunction. In some cases, a light-shielding film (hereinafter simply referred to as a “pinpoint light-shielding part”) that shields light in a portion where leakage current easily occurs is provided.

  For example, Patent Document 1 discloses a technique of shielding light by a scanning line functioning as a gate electrode in a channel region of a TFT. According to Patent Document 2, light reaching the channel region of the TFT is reduced by providing a plurality of light-shielding films formed on the channel region and a layer that absorbs internally reflected light. Patent Document 3 discloses a technique for reducing incident light incident on the channel region of the TFT as much as possible while ensuring a preferable operation of the TFT and narrowing the scanning line.

JP 2004-4722 A Japanese Patent No. 3731447 JP 2003-262888 A

  However, in the above-described technique, since the storage capacitor is formed in a planar manner in the pinpoint light shielding portion, the pinpoint light shielding portion having a relatively large area for light shielding cannot be effectively used. That is, since the storage capacitor can be formed only in the area when viewed in plan, there is a technical problem that the arrangement efficiency is low from the viewpoint of increasing the aperture ratio in the display region.

  The present invention has been made in view of the above-described problems, for example, an electro-optical device such as a liquid crystal device driven by an active matrix method, and can display a higher quality image by increasing a storage capacity. It is an object of the present invention to provide an electro-optical device that can perform the above and an electronic apparatus including the electro-optical device.

An electro-optical device according to one embodiment of the present invention includes a data line and a scanning line that extend so as to cross each other, a transistor that is electrically connected to the data line and the scanning line, and a transistor that corresponds to the transistor. A pixel electrode, a light shielding film provided so as to cover a predetermined region of the transistor, at least one step portion provided on the light shielding film, and a storage capacitor formed on the step portion. The light shielding film extends along the pixel electrode side LDD region disposed between the pixel electrode side source / drain region electrically connected to the pixel electrode and the channel region of the transistor. An extension portion extending to the first side and the second side, and disposed in the same layer as a gate electrode of the transistor electrically connected to the scan line; The data line and the scanning line are at least partially disposed inside an intersecting region where the data line and the scanning line intersect, as viewed from a direction intersecting the scanning line and the scanning line. The insulating film is formed by locally laminating so as to overlap the pixel electrode side LDD region.
The electro-optical device according to the present invention includes a substrate, a data line and a scanning line extending crossing each other on the substrate, a transistor electrically connected to the data line and the scanning line, A pixel electrode provided corresponding to the transistor, a light shielding film provided so as to cover a predetermined region of the transistor, at least one step portion provided on the light shielding film, and formed on the step portion Storage capacity.

  According to the electro-optical device of the present invention, during the operation, for example, the scanning signal is supplied from the scanning line while the supply of the image signal from the data line to the pixel electrode is controlled, so that an image display by a so-called active matrix system is possible. Become. The image signal is transferred from the data line to the transistor at a predetermined timing by turning on / off a transistor, which is a switching element electrically connected between the data line and the pixel electrode, according to a scanning signal supplied from the scanning line. And is supplied to the pixel electrode provided corresponding to the transistor. The pixel electrode is a transparent electrode made of a transparent conductive material such as ITO (Indium Tin Oxide), for example, and a plurality of pixel electrodes are provided in a matrix form in a region to be a display region on the substrate corresponding to the intersection of the data line and the scanning line. It is done.

  The transistor described above includes, for example, a semiconductor layer having a channel region, a data line side source / drain region, and a pixel electrode side source / drain region, a gate electrode overlapping the channel region, and a gate insulating film disposed between the semiconductor layer and the gate electrode. Is built by. Note that the transistor may be a double-gate thin film transistor in which two gate electrodes are sandwiched from the top or bottom of the semiconductor layer or two gate electrodes exist in two channel regions connected in series. Furthermore, there may be three or more gate electrodes.

  Here, in the present invention, in particular, the light shielding film is provided so as to cover a predetermined region in the above-described transistor. Here, the “predetermined region” is a region where the light shielding capability is enhanced by providing a light shielding film, and is typically a region where light leakage current is relatively likely to occur, such as an LDD (Lightly Doped Drain) region. It is. For example, the light shielding film is disposed so as to overlap with a predetermined region in plan view. Further, the light may be arranged so as not to overlap the predetermined area so as to block light that is about to enter from an oblique direction. That is, “so as to cover the predetermined area” means that the light is to be shielded from light that is about to enter the predetermined area. By being arranged in this way, the light shielding film has an area corresponding to a predetermined region as viewed in plan on the substrate.

  On the light shielding film described above (that is, the surface of the light shielding film or the surface of the layer disposed on the upper layer side of the light shielding film), at least one step portion is provided. The step portion may be a convex portion or a concave portion. Further, the “stepped portion” here refers to the entire convex portion and concave portion. That is, the step portion may have a surface parallel to the substrate in addition to the side wall formed perpendicularly or obliquely to the substrate. In other words, the stepped portion may have two or more continuous surfaces having different angles in the stepped portion. The stepped portion may be caused by unevenness on the surface serving as the base of the light shielding film. For example, the stepped portion may be provided by forming a light shielding film having a uniform film thickness on the ground under the unevenness. . Alternatively or in addition, the stepped portion may be caused by a change in the thickness of the light shielding film itself. For example, the stepped portion is formed by forming a light shielding film whose thickness changes on a flat base surface. A part may be provided.

  As described above, in the present invention, in order to effectively exhibit the light shielding performance, the light shielding film is formed so as to have a relatively large area when viewed in plan on the substrate. For this reason, it is possible to easily and more form the stepped portions as described above on the light shielding film.

  In the present invention, a storage capacitor is further formed in the above-described stepped portion. The storage capacitor includes, for example, an upper electrode, a lower electrode, and a capacitor insulating film formed between the upper electrode and the lower electrode. Here, in particular, since the storage capacitor is formed in the stepped portion, it has at least two portions having different heights. That is, the storage capacitor typically includes a three-layer structure portion laminated in parallel to the substrate and a three-layer structure portion laminated so as to be inclined, steeply inclined, or perpendicular to the substrate. Will have.

  By forming the storage capacitor in this way, the capacity area of the storage capacitor becomes larger than when formed on a flat surface, for example. That is, the capacity area is increased by the amount formed on the side wall of the step portion. Further, by forming the storage capacitor three-dimensionally using the stepped portion, it is possible to increase the capacitance without increasing the area when viewed in plan with respect to the substrate. This is extremely effective when, for example, the area where the storage capacitor can be arranged becomes small in order to reduce the size of the device or improve the aperture ratio.

  The effect as described above is typically more pronounced as the number of the stepped portions is larger. For example, from the viewpoint of preventing a highly complicated manufacturing process, only one stepped portion is provided. Even if it is not provided, it can be fully exerted.

  As described above, according to the electro-optical device according to the present invention, it is possible to effectively arrange the storage capacitor and increase the capacitance by using the light-shielding film having a relatively large area. is there. Therefore, a high quality image can be displayed.

  In one aspect of the electro-optical device of the present invention, the predetermined region of the transistor is a pixel electrode side LDD disposed between a channel region of the transistor and a pixel electrode side source / drain region electrically connected to the pixel electrode. It is an area.

  According to this aspect, the transistor includes a channel region, a pixel electrode side source / drain region electrically connected to the pixel electrode, and a pixel electrode side LDD region disposed between the channel region and the pixel electrode side source / drain region. Comprising. That is, the transistor has an LDD structure.

  Here, in this embodiment, in particular, the light shielding film shields light using the above-described pixel electrode side LDD region as a predetermined region. The pixel electrode side LDD region is an impurity region formed by implanting impurities into the semiconductor layer by impurity implantation such as an ion implantation method, and is relatively easy to generate a light leakage current. If a light leakage current is generated in the pixel electrode side LDD region, the current flowing in the data line side source / drain region and the pixel electrode side source / drain region when the transistor is turned off due to the characteristics of the transistor having the LDD structure. (Ie, off-current) increases.

  However, in this embodiment, in particular, light incident on the pixel electrode side LDD region can be effectively shielded by the light shielding film. Therefore, an increase in off current as described above can be effectively prevented, and a high-quality image can be displayed.

  Further, since the light shielding film has an area corresponding to the pixel electrode side LDD region, it is possible to more easily form a plurality of stepped portions as described above. Therefore, the storage capacity can be effectively increased and a higher quality image can be displayed.

  In another aspect of the electro-optical device of the present invention, the light-shielding film is formed in the same layer as the gate electrode of the transistor that is electrically connected to the scanning line.

  According to this aspect, the transistor includes the gate electrode. The gate electrode is electrically connected to or integrated with the scan line, and supplies a scan signal to the transistor.

  In this embodiment, in particular, the light shielding film and the gate electrode described above are formed in the same layer. Here, the “same layer” means a layer formed by the same film forming process, and for example, the thickness of the layer may be different from each other. By forming the light shielding film and the gate electrode in the same layer, the number of steps in the manufacturing process can be prevented from increasing in order to form the light shielding film. That is, it is possible to prevent the manufacturing process from becoming highly complicated and prolonged.

  In the above-described aspect in which the light shielding film and the gate electrode are formed in the same layer, the light shielding film may be formed integrally with the gate electrode.

  If comprised in this way, a light shielding film and a gate electrode will be formed integrally. Here, the gate electrode is typically formed to face the semiconductor layer in the transistor. Therefore, by integrally forming the light shielding film and the gate electrode, the light shielding film can be disposed closer to the semiconductor layer. Therefore, the light that enters the semiconductor layer can be effectively shielded by the light shielding film. Therefore, it is possible to more effectively prevent the occurrence of light leakage current and display a high-quality image.

  In another aspect of the electro-optical device according to the aspect of the invention, the light-shielding film is at least partially disposed in an intersecting region where the data line and the scanning line intersect with each other when viewed in plan on the substrate.

  According to this aspect, the light shielding film is disposed at least partially in the intersecting region where the scanning lines and the data lines intersect when viewed in plan on the substrate. For this reason, the predetermined area shielded by the light shielding film is shielded by the intersection area in addition to the light shielding film. In the intersecting region, the light shielding performance is enhanced by the intersection of the scanning line and the data line. Therefore, it is possible to more effectively shield light that is about to enter the predetermined area. Therefore, it is possible to more effectively prevent the occurrence of light leakage current and display a high-quality image.

  In another aspect of the electro-optical device according to the aspect of the invention, the step portion is formed by locally laminating insulating films.

  According to this aspect, the step portion is formed by locally laminating the insulating film. Note that “locally laminated” includes both the case of forming an island-shaped insulating film and the case of forming an insulating film in which holes are dug. It does not matter whether the insulating film is a single layer or a multilayer. The insulating film is laminated, for example, and then patterned by etching or the like to form a stepped portion. By forming the step portion in this way, the step portion can be formed more easily. Therefore, it is possible to prevent the manufacturing process from becoming highly complicated and prolonged.

  In another aspect of the electro-optical device according to the aspect of the invention, the stepped portion is provided in an upper layer of the light shielding film subjected to the planarization process.

  According to this aspect, first, the flattening process is performed on the light shielding film. The planarization process may be performed by forming the light shielding film itself by CMP (Chemical Mechanical Polishing), for example, or by stacking a planarization insulating film or the like on the light shielding film. May be.

  If such a flattening process is not performed, the surface of the light shielding film remains uneven due to the presence of wirings, electrodes, and the like arranged on the lower layer side of the light shielding film. Therefore, the step portion is formed on such irregularities.

  However, in this embodiment, since the unevenness as described above is flattened, the stepped portion is formed on the flattened surface. Therefore, it is possible to prevent a variation in the height of the stepped portion and to form a stepped portion having a desired height. Accordingly, the capacity can be stably increased.

  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 the electro-optical device according to the present invention described above is provided, a projection display device, a television, a mobile phone, an electronic notebook, and a word processor capable of performing high-quality 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. Further, as the electronic apparatus of the present invention, for example, an electrophoretic device such as electronic paper can be realized.

  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 TFT active matrix driving type liquid crystal device with a built-in driving circuit, which is an example of the electro-optical device of the present invention, is taken as an example.

<First embodiment>
First, the overall configuration of the liquid crystal device according to the first embodiment will be described with reference to FIGS. 1 and 2. Here, FIG. 1 is a schematic plan view of the liquid crystal device as seen from the side of the counter substrate together with the components formed on the TFT array substrate, and FIG. 'Cross section.

  1 and 2, the liquid crystal device according to the present embodiment includes a TFT array substrate 10 and a counter substrate 20 which are arranged to face each other. The TFT array substrate 10 is a transparent substrate such as a quartz substrate, a glass substrate, or a silicon substrate. The counter substrate 20 is also a transparent 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 provided in a seal material provided in a seal region around the image display region 10a. 52 are bonded to each other.

  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. The liquid crystal device according to this embodiment is small and suitable for performing enlarged display for a light valve of a projector.

  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.

  On the TFT array substrate 10, 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.

  In the peripheral region on the TFT array substrate 10, the data line driving circuit 101 and the external circuit connection terminal 102 are provided along one side of the TFT array substrate 10 on the outer peripheral side from 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. Thus, the 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 in which pixel switching TFTs as drive elements, wiring lines such as scanning lines and data lines are formed is formed. In the image display area 10a, pixel electrodes 9a are provided in a matrix on the upper layer of wiring such as pixel switching TFTs, scanning lines, and data lines. An alignment film 16 is formed on the pixel electrode 9a. In the present embodiment, the pixel switching element may be constituted by various transistors, TFD, or the like in addition to the TFT.

  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. A counter electrode 21 made of a transparent material such as ITO is formed on the light shielding film 23 (below the light shielding film 23 in FIG. 2) so as to face the plurality of pixel electrodes 9a. An alignment film 22 is formed on the upper side (below the counter electrode 21 in FIG. 2).

  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 a 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, an electrical configuration of the pixel portion 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 a and a TFT 30 as an example of a “transistor” according to the present invention are formed in each of a plurality of pixels formed in a matrix form that constitutes the image display region 10 a. The TFT 30 is electrically connected to the pixel electrode 9a, and performs switching control of the pixel electrode 9a during operation of the liquid crystal device. The data line 6a to which the image signal is supplied is electrically connected to the source of the TFT 30. The image signals S1, S2,..., Sn written to the data lines 6a may be supplied line-sequentially in this order, or may be supplied for each group to a plurality of adjacent data lines 6a. Good.

  The scanning line 11a 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 11a in this order at a predetermined timing. It is configured to apply line-sequentially. The pixel electrode 9a is electrically connected to the drain of the TFT 30, and the image signal S1, S2,..., Sn supplied from the data line 6a is obtained by closing the TFT 30 as a switching element for a certain period. It is written at a predetermined timing. Image signals S 1, S 2,..., Sn written in a liquid crystal as an example of an electro-optical material via the pixel electrode 9 a are held for a certain period with the counter electrode formed on the counter substrate.

  The liquid crystal constituting the liquid crystal layer 50 (see FIG. 2) modulates light and enables gradation display by changing the orientation and order of the molecular assembly depending on the applied voltage level. In the normally white mode, the transmittance for incident light is reduced according to the voltage applied in units of each pixel, and in the normally black mode, the light is incident according to the voltage applied in units of each pixel. The transmittance for light is increased, and light having a contrast corresponding to an image signal is emitted from the liquid crystal device as a whole.

  In order to prevent the image signal held here from leaking, a storage capacitor 70 is added electrically in parallel with the liquid crystal capacitor formed between the pixel electrode 9a and the counter electrode 21 (see FIG. 2). ing. The storage capacitor 70 is a capacitive element that functions as a storage capacitor that temporarily holds the potential of each pixel electrode 9a in response to supply of an image signal. The storage capacity 70 will be described in detail below.

  Next, the storage capacity of the liquid crystal device according to the present embodiment will be described with reference to FIGS. FIG. 4 is a plan view showing the configuration of the storage capacitor of the liquid crystal device according to the first embodiment. 5 is a cross-sectional view taken along line A-A ′ in FIG. 4, and FIG. 6 is a cross-sectional view taken along line C-C ′ in FIG. 4. FIG. 6 is a plan view showing a modification of the liquid crystal device according to the first embodiment.

  In FIGS. 4 to 7, the scales of the respective layers and members are made different in order to make each layer and each member recognizable on the drawing. This is the same for the corresponding drawings described later. 4 to 7, only the configuration on the TFT array substrate side in the configuration described with reference to FIG. 1 or FIG. 2 will be described. However, for convenience of explanation, in these drawings, a portion positioned above the pixel electrode 9 a is described. Is omitted. Hereinafter, the configuration of the storage capacitor 70 will be described in detail together with the configuration of the TFT 30, and description of other configurations will be omitted as appropriate.

  In FIG. 4, data lines 6a and scanning lines 11a are provided on the TFT array substrate 10 so as to cross each other. The scanning line 11a extends along the X direction in FIG. 4, and the data line 6a extends along the Y direction in FIG. A pixel switching TFT 30 is provided at each of the locations where the scanning line 11a and the data line 6a intersect each other.

  The scanning line 11a, the data line 6a and the TFT 30, the storage capacitor 70 and the lower light-shielding film 110 described later correspond to the pixel electrodes 9a (see FIG. 3) when viewed in plan on the TFT array substrate 10. The pixel is disposed in a non-opening region that surrounds the opening region of the pixel (that is, a region where light that actually contributes to display is transmitted or reflected in each pixel). That is, the scanning lines 11a, the data lines 6a, the TFTs 30, the storage capacitors 70, and the lower light-shielding film 110 are arranged not in the opening area of each pixel but in the non-opening area so as not to hinder display. .

  The non-opening region is defined by, for example, a light shielding film in which at least a part of the conductive film constituting the data line 6a, the scanning line 11a, or the storage capacitor 70 on the TFT array substrate 10 side has a light shielding property. Thus, the region that can block light incident on each pixel is defined on the TFT array substrate 10 side. More specifically, the non-opening region includes a first region 99ba along the Y direction and a second region 99bb along the X direction. Preferably, as described with reference to FIG. 2, the non-opening region is defined together with the light shielding film on the TFT array substrate 10 side by the light shielding film 23 formed on the counter substrate 20 side.

  Hereinafter, the components of the pixel portion illustrated in FIG. 5 will be described in order from the lower layer side.

  In FIG. 5, the lower light-shielding film 110 is disposed on the TFT array substrate 10, and is a light-shielding conductive material such as a refractory metal material such as tungsten (W), titanium (Ti), or titanium nitride (TiN). Consists of. Further, as shown in FIG. 4, the lower light-shielding film 110 is formed, for example, along the extending direction of the scanning line 11a (that is, the X direction), that is, an image display area corresponding to each scanning line 11a. 10a is formed in a stripe shape. According to the lower light-shielding film 110 as described above, the TFT 30 of the return light such as the back surface reflection on the TFT array substrate 10 or the light emitted from another liquid crystal device by a multi-plate projector or the like and penetrating through the composite optical system. It is possible to block the light traveling forward. Furthermore, the lower light shielding film 110 can be made to function redundantly as the scanning line 11a by being electrically connected to the scanning line 11a through a contact hole or the like.

  The base insulating film 12 is made of, for example, a silicon oxide film. The underlying insulating film 12 is formed on the entire surface of the TFT array substrate 10, thereby preventing a change in characteristics of the pixel switching TFT 30 due to roughness during polishing of the surface of the TFT array substrate 10 or dirt remaining after cleaning. Have.

  In FIG. 4, the TFT 30 includes a semiconductor layer 1a and a gate electrode 3a.

  The semiconductor layer 1a is made of, for example, polysilicon, and has a channel region 1a ′ having a channel length along the Y direction in FIG. 4, a data line side LDD region 1b, a pixel electrode side LDD region 1c, and a data line side source / drain region 1d. And the pixel electrode side source / drain region 1e. That is, the TFT 30 has an LDD structure.

  The data line side source / drain region 1d and the pixel electrode side source / drain region 1e are formed substantially in mirror symmetry along the Y direction with respect to the channel region 1a '. That is, the data line side LDD region 1b is formed between the channel region 1a 'and the data line side source / drain region 1d. The pixel electrode side LDD region 1c is formed between the channel region 1a 'and the pixel electrode side source / drain region 1e. The data line side LDD region 1b, the pixel electrode side LDD region 1c, the data line side source / drain region 1d, and the pixel electrode side source / drain region 1e are formed by implanting impurities into the semiconductor layer 1a by an impurity implantation such as an ion implantation method. This is an impurity region. The data line side LDD region 1b and the pixel electrode side LDD region 1c are formed as low concentration impurity regions with less impurities than the data line side source / drain region 1d and the pixel electrode side source / drain region 1e, respectively. According to such an impurity region, when the TFT 30 is not operating, it is possible to reduce the off current flowing in the source region and the drain region, and to suppress the decrease in the on current flowing when the TFT 30 is operating. The TFT 30 preferably has an LDD structure. However, the TFT 30 may have an offset structure in which no impurity implantation is performed in the data line side LDD region 1b and the pixel electrode side LDD region 1c. A self-alignment type in which the data line side source / drain region and the pixel electrode side source / drain region are formed by implanting the concentration may be used.

  The scanning line 11a is arranged above the semiconductor layer 1a via an insulating film 202 made of, for example, a silicon oxide film. The scanning line 11a is made of, for example, conductive polysilicon and is formed so as to extend in the X direction. A gate electrode 3a having a light shielding property is formed as a part of the scanning line 11a.

  In FIG. 6, the gate electrode 3 a is provided so as to overlap the channel region 1 a ′ in plan view with the gate insulating film 2 interposed therebetween. Furthermore, in addition to the channel region 1a ′, the gate electrode 3a is provided so as to overlap the data line side LDD region 1b and the data line side source / drain region 1d, and the pixel electrode side LDD region 1c and the pixel electrode side source / drain region 1e. May be.

  In the present embodiment, in particular, the gate electrode 3a has a light shielding property. That is, the gate electrode 3a is an example of the “light-shielding film” in the present invention. For example, the gate electrode 3a blocks light that is about to enter the pixel electrode side LDD region 1c from the upper layer side. For this reason, on the condition that the gate electrode 3a fulfills the original function of the gate, for example, an opaque polysilicon film, metal film, metal silicide film, etc. having excellent light shielding properties such as high reflectance or high light absorption Preferably, it is composed of a single layer or multiple layers. However, as long as the material of the gate electrode 3a has a light shielding ability (that is, a light reflection ability or a light absorption ability), the pixel electrode side LDD region 1c can be used as long as it has the unique shape and arrangement as described above. On the other hand, the function of blocking the light to be incident can be obtained accordingly.

  Returning to FIG. 4, the pixel electrode side LDD region 1 c is arranged in an intersecting region 99 cr where the first region 99 ba and the second region 99 bb intersect each other in the non-opening region. In the intersecting region 99cr, among the light incident on the pixel electrode side LDD region 1c from the upper layer side, the light traveling along the traveling direction indicated by the arrow Py in FIG. 4 is shielded by the first region 99ba. The light traveling along the traveling direction indicated by the arrow Px in FIG. 4 can be shielded by the second region 99bb. In FIG. 4, an arrow Py indicates an example of the traveling direction of light having a component traveling along the Y direction, and an arrow Px indicates an example of the traveling direction of light having a component traveling along the X direction. It is shown.

  As described above, in this embodiment, by using the intersection region 99cr in addition to the gate electrode 3a, the light that travels to the pixel electrode side LDD region 1c is effectively used as the pinpoint light shielding region 500. Shaded. Here, the “pinpoint light shielding region” means a light shielding region that mainly shields a portion where a leak current is likely to occur, and is synonymous with the above-described pinpoint light shielding portion. Note that the pinpoint light blocking region 500 has a relatively large area in order to further improve the light blocking performance. That is, as shown in FIG. 4, the width of the scanning line 11a is locally increased, thereby enabling more effective light shielding.

  The details will be described later. In particular, when light is applied to the pixel electrode side LDD region 1c, light leakage in the TFT 30 is compared to when light is applied to the data line side LDD region 1b. The present inventor has inferred that current is likely to occur. In the present embodiment, the light-shielding property for the pixel electrode side LDD region 1c among the various regions formed in the semiconductor layer 1a can be improved in a pinpoint manner. Therefore, the light leakage current of the TFT 30 of each pixel can be effectively reduced.

  Further, in the present embodiment, the light shielding property for the pixel electrode side LDD region 1c can be improved pinpointly without providing a light shielding region separately from the intersection region 99cr for the pixel electrode side LDD region 1c. Therefore, by providing a region for improving the light shielding property at such a pinpoint, it is possible to increase the arrangement area of the non-opening region 99b of each pixel and prevent the opening region 99a from becoming smaller. . As a result, even if each pixel is miniaturized, it is possible to improve the light shielding property and improve the aperture ratio.

  In FIG. 5, on the upper layer side of the TFT 30 on the TFT array substrate 10, the surface of the layer is flattened by forming the interlayer insulating film 41. The planarization process is performed by, for example, CMP. However, even when such a planarization process is not performed, an effect of increasing the capacity described later can be obtained. In other words, a step portion which will be described later may be formed by using the uneven portion remaining by not performing the flattening process.

  A step forming film 200 is formed on the flattened interlayer insulating film 41. The step forming film 200 is formed so as to cover the entire surface of the non-opening region, for example, and then patterned by etching or the like to form a stepped portion. The stepped portion is typically formed at a position where a storage capacitor 70 to be described later is formed. Here, the pixel electrode side LDD region 1c is particularly utilized by utilizing the pinpoint light shielding region 500 having a large area. It is formed in the position which overlaps. In other words, the presence of the pinpoint light shielding area 500 makes it possible to form the stepped portion as described above.

  A storage capacitor 70 is formed in an upper layer of the step forming film 200 so as to straddle the formed step portion. The storage capacitor 70 is formed by arranging a lower electrode 71 and an upper electrode 300 to face each other with a capacitor insulating film 75 interposed therebetween. A spacer insulating film 210 is formed between the upper electrode 300 and the capacitor insulating film 75. The spacer insulating film 210 prevents the lower electrode 71 from being damaged when the upper electrode 300 is patterned by etching or the like.

  The upper electrode 300 extends from the image display region 10a in which the pixel electrode 9a is disposed to the periphery thereof, and is electrically connected to a constant potential source. Thereby, the upper electrode 300 is maintained at a fixed potential, and can function as a fixed potential side capacitor electrode. The upper electrode 300 is formed of a non-transparent metal film containing a metal or alloy such as Al (aluminum) or Ag (silver), for example, and also functions as an upper light shielding film (built-in light shielding film) that shields the TFT 30. . The upper electrode 300 is made of, for example, at least one of refractory metals such as Ti (titanium), Cr (chromium), W (tungsten), Ta (tantalum), Mo (molybdenum), and Pd (palladium). It may be composed of a simple metal, an alloy, a metal silicide, a polysilicide, or a laminate of these.

  The lower electrode 71 is a pixel potential side capacitor electrode electrically connected to the pixel electrode side source / drain region 1e of the TFT 30 and the pixel electrode 9a. More specifically, the lower electrode 71 is electrically connected to the pixel electrode side source / drain region 1e through the contact hole 83 (see FIG. 4) and relayed through the contact hole 84 (see FIG. 4). Electrically connected to the layer. Although not shown here, the relay layer is electrically connected to the pixel electrode 9a through a contact hole, for example. That is, the lower electrode 71 relays the electrical connection between the pixel electrode side source / drain region 1e and the pixel electrode 9a together with the relay layer. The lower electrode 71 is made of, for example, conductive polysilicon, or a non-transparent metal film containing a metal or alloy such as Al (aluminum).

  Here, the lower electrode 71 preferably has a function as a light absorbing layer or a light shielding film disposed between the upper electrode 300 as the upper light shielding film and the TFT 30 in addition to a function as a pixel potential side capacitance electrode. . Accordingly, in the intersecting region 99cr, the light incident on the pixel electrode side LDD region 1c from the upper layer side can also be shielded by each of the upper electrode 300 and the lower electrode 71.

  The dielectric film 75 has a single layer structure or a multilayer structure composed of a silicon oxide film such as an HTO (High Temperature Oxide) film, an LTO (Low Temperature Oxide) film, or a silicon nitride film.

  Here, in particular, since the storage capacitor 70 is formed in the stepped portion, it has at least two portions having different heights. For this reason, the capacity area of the storage capacitor 70 is larger than, for example, when it is formed on a flat surface. That is, the capacity area increases as the storage capacitor 70 is formed on the side wall of the stepped portion. Further, by forming the storage capacitor 70 three-dimensionally using the stepped portion, it is possible to increase the capacity without increasing the area when viewed in plan with respect to the substrate 10. This is extremely effective when, for example, the area where the storage capacitor can be arranged becomes small in order to reduce the size of the device or improve the aperture ratio. In this way, by forming the step portion using the area of the pinpoint light shielding region 500, it is possible to effectively increase the capacity of the storage capacitor 70.

  In FIG. 7, a plurality of step portions formed in the pinpoint light shielding region 500 may be formed. For example, as shown in FIG. 7, by forming four step portions, the capacity can be increased more effectively than in the case shown in FIG. That is, when the pinpoint region 500 having a large area is provided as in this embodiment, it is possible to increase the capacity more effectively by forming more stepped portions. .

  Returning to FIG. 5, the data line 6 a is formed in the upper layer of the storage capacitor 70 via the interlayer insulating film 42. The data line 6a is connected to the data line side source / drain region 1d of the semiconductor layer 1a via a contact hole 81 (see FIG. 4) penetrating the insulating film 202, the interlayer insulating film 41, the capacitor insulating film 75, and the interlayer insulating film. Electrically connected. The data line 6a and the inside of the contact hole 81 are made of, for example, an Al (aluminum) -containing material such as Al—Si—Cu or Al—Cu, Al alone, or a multilayer film including an Al layer and a TiN layer. The data line 6a also has a function of shielding the TFT 30 from light.

  The pixel electrode 9a is formed on the upper layer side of the data line 6a via the interlayer insulating film 43. The pixel electrode 9a is electrically connected to the pixel electrode side source / drain region 1e of the semiconductor layer 1a via the lower electrode 71.

  The configuration of the pixel portion described above is common to each pixel portion. Such pixel portions are periodically formed in the image display area 10a (see FIG. 1).

  Here, the reason why the light leakage current is more likely to occur in the pixel electrode side LDD region 1c than in the data line side LDD region 1b during the operation of the TFT 30 described above with reference to FIGS. This will be described in detail.

  First, a measurement result obtained by measuring the magnitude of the drain current when light is applied to the test TFT will be described with reference to FIG. FIG. 8 is a graph showing the relationship between the light irradiation position and the drain current in the test TFT.

  In FIG. 8, data E1 scans a light spot (approximately 2.4 um visible light laser) sequentially from the drain region side to the source region side for a single TFT for test, ie, TEG (Test Element Group). The result of having measured the magnitude | size of the drain current at the time of irradiating is shown. TEG includes a channel region, a source region, and a drain region, a source side junction region formed at a junction between the channel region and the source region, and a drain side junction region formed at a junction between the channel region and the drain region. have.

  The horizontal axis in FIG. 8 indicates the light irradiation position where the light spot is irradiated. The boundary between the channel region and the drain side junction region, the boundary between the channel region and the source side junction region, and the channel region are zeroed. It is said. The vertical axis in FIG. 8 indicates the magnitude of the drain current (however, a relative value normalized by a predetermined value). When the drain current flows from the drain region to the source region, the vertical axis is positive. When the drain current is flowing from the source region to the drain region, a negative value (that is, a negative value) is indicated.

  In FIG. 8, data E1 shows a positive value at any light irradiation position. That is, the drain current flows from the drain region toward the source region. Data E1 shows a larger value in the drain side junction region than in the source side junction region. That is, when the light spot is irradiated into the drain side junction region, the drain current becomes larger than when the light spot is irradiated into the source side junction region. That is, when the light spot is irradiated into the drain side junction region, the light leakage current becomes larger than when the light spot is irradiated into the source side junction region. Note that the drain current includes dark current (or subthreshold leakage, that is, leakage current that flows between the source region and the drain region even when light is not irradiated) and optical leakage current (or photoexcitation current, that is, Current generated by excitation of electrons due to light irradiation).

  Next, a mechanism in which the light leakage current is larger when the light spot is irradiated in the drain side junction region than when the light spot is irradiated in the source side junction region will be described with reference to FIGS. 9 and 10. Will be described with reference to FIG. FIG. 9 is a conceptual diagram showing the behavior of carriers when photoexcitation occurs in the drain side junction region. FIG. 10 is a conceptual diagram showing the behavior of carriers when photoexcitation occurs in the source-side junction region. 9 and 10, assuming that the above-described pixel electrode 9a to which the TFT 30 is electrically connected is displayed with an intermediate gradation, the source potential (that is, the potential of the source region) is 4.5 V, and the gate potential. (That is, the potential of the channel region) is 0 V, and the drain potential (that is, the potential of the drain region) is 9.5 V. The horizontal axis of FIG.9 and FIG.10 has shown each area | region in the semiconductor layer which comprises TEG. 9 and 10 indicate the electron potential (Fermi level). Since electrons have a negative charge, the higher the potential in each region, the lower the potential of the electrons, and the lower the potential in each region, the higher the potential of the electrons.

  FIG. 9 shows the behavior of carriers when a light spot is irradiated to the drain side junction region formed between the channel region and the drain region, and photoexcitation occurs in the drain side junction region.

  In FIG. 9, it can be estimated that the light leakage current consists of two current components.

  That is, as the first current component, there is a current component due to movement of electrons generated by photoexcitation. More specifically, a current component (this current component) generated when electrons generated by photoexcitation in the drain side junction region (see “e” in the figure) move from the drain side junction region to the drain region having a lower potential. Is from the drain region to the source region).

  As the second current component, there is a current component due to movement of holes generated by photoexcitation (that is, holes, see “h” in the figure). More specifically, the bipolar effect generated by the movement of holes generated by photoexcitation in the drain side junction region from the drain side junction region to the channel region having a lower potential (that is, the electron potential is higher). This is the resulting current component. That is, the positive charge of the holes that have moved to the channel region reduces the potential of the channel region (that is, the so-called base potential) from the potential Lc1 to the potential Lc2, thereby increasing the number of electrons traveling from the source region to the drain region. (This current component flows from the drain region to the source region). Therefore, when photoexcitation occurs in the drain side junction region, the first and second current components are both in the direction of increasing the drain current (in other words, the collector current) (that is, the direction of flowing from the drain region to the source region). Occur.

  FIG. 10 shows the behavior of carriers when a light spot is irradiated on the source side junction region formed between the channel region and the source region, and photoexcitation occurs in the source side junction region.

  In FIG. 10, unlike the case where photoexcitation occurs in the drain side junction region described above with reference to FIG. 9, the photoleakage current has a lower potential from the source side junction region (that is, the electron potential is more It can be assumed that the second current component due to the bipolar effect moving to the (high) channel region is dominant. That is, a first current component (this current component is expressed as a result of electrons generated by photoexcitation in the source side junction region (see “e” in the figure) moving from the source side junction region to the source region having a lower potential). , Which flows from the source region to the drain region) can be estimated to be less than the second current component caused by the bipolar effect (this current component flows from the drain region to the source region).

  In FIG. 10, since the base potential is pulled down from the potential Lc1 to the potential Lc3 by the second current component (that is, the positive charge of the holes moved to the channel region) due to the bipolar effect, the source region moves from the source region to the drain region. The current component due to the effect of increasing electrons flows from the drain region to the source region. On the other hand, the first current component described above flows from the source region to the drain region. That is, the first current component and the second current component flow in opposite directions. Here, in FIG. 8 again, when the light spot is irradiated to the source-side junction region, the drain current (see data E1) shows a positive value. That is, in this case, the drain current flows from the drain region toward the source region. Therefore, it can be said that the first current component only suppresses the current component due to the bipolar effect, which is the dark current and the second current component, and is not large enough to direct the flow of the drain current from the source region to the drain region. .

  Further, since the potential difference between the channel region and the source region is smaller than the potential difference between the channel region and the drain region, the depletion region on the source region side (that is, the source side junction region) is depleted on the drain region side ( That is, it is narrower than the drain side junction region. For this reason, when the light spot is irradiated on the source-side junction region, the absolute amount of photoexcitation is smaller than when the light spot is irradiated on the drain-side junction region.

  As described above with reference to FIGS. 9 and 10, when photoexcitation occurs in the drain side junction region, both the first and second current components are generated in the direction of increasing the drain current. On the other hand, when photoexcitation occurs in the source side junction region, the first current component suppresses the second current component. Therefore, when the light spot is irradiated in the drain side junction region, the drain current becomes larger (that is, the light leakage current becomes larger) than when the light spot is irradiated in the source side junction region. .

  Next, when the pixel electrode side source / drain region is set to the drain potential and the light spot is irradiated into the pixel electrode side junction region, the data line side source / drain region is set to the drain potential and the data line side A mechanism in which the light leakage current becomes larger than that in the case where the light spot is irradiated in the junction region will be described with reference to FIGS. FIG. 11 is a conceptual diagram showing the behavior of carriers when photoexcitation occurs in the data line side junction region (in other words, the drain side junction region) when the data line side source / drain region is at the drain potential. is there. FIG. 12 is a conceptual diagram showing the behavior of carriers when photoexcitation occurs in the pixel electrode side junction region (in other words, the drain side junction region) when the pixel electrode side source / drain region is at the drain potential.

  In the following, a case where charge is held in a pixel portion including a pixel switching TFT and photoexcitation occurs will be considered. The difference from the case of assuming the TEG as described above is that the pixel electrode side of the pixel switching TFT can be in a floating state. A storage capacitor such as a storage capacitor 70 may be connected to the pixel electrode side of the pixel switching TFT. If the capacitance value is sufficiently large, the state is close to a fixed electrode as in the case of using the TEG described above. However, if the capacitance is not sufficiently large, it becomes a floating state or a state close to this. Here, it is assumed that the capacitance value is not sufficiently large.

  11 and 12, the liquid crystal device employs AC driving in order to prevent so-called burn-in. Here, it is assumed that halftone display is assumed, and the pixel electrode holds a negative field charge of 4.5 V and a positive field charge of 9.5 V alternately with 7 V as a reference potential. To do. For this reason, the source and drain of the pixel switching TFT are not fixed and change between the pixel electrode side source / drain region and the data line side source / drain region. That is, as shown in FIG. 11, when a negative field charge is held in the pixel electrode (that is, the potential of the pixel electrode side source / drain region is lower than the potential of the data line side source / drain region), The pixel electrode side source / drain region is a source, whereas, as shown in FIG. 12, when a positive field charge is held in the pixel electrode (that is, the potential of the pixel electrode side source / drain region becomes the data line side source When it becomes higher than the potential of the drain region), the pixel electrode side source / drain region becomes the drain.

  In FIG. 11, when a negative field charge is held in the pixel electrode, the pixel electrode side source / drain region becomes the source (or emitter), and the data line side source / drain region becomes the drain (or collector). When photoexcitation occurs in the data line side junction region, which is the drain side junction region, as described above, the first current component due to the movement of electrons generated by photoexcitation and the second current component due to the bipolar effect are generated. . Here, when the second current component due to the bipolar effect occurs (that is, the base potential is pulled down from the potential Lc1 to the potential Lc2, and the source / drain region from the pixel electrode side to the data line side to the source / drain to be the drain) When the electrons move to the region), electrons are extracted from the pixel electrode side source / drain region in a floating state, and the potential of the pixel electrode side source / drain region as an emitter decreases from the potential Ls1 to the potential Ls2 ( The potential rises). That is, when photoexcitation occurs in the data line side junction region which is the drain side junction region, the base potential is lowered and the potential of the pixel electrode side source / drain region as the emitter is also lowered. In other words, when photoexcitation occurs in the data line side junction region, which is the drain side junction region, the emitter potential also increases as the base potential increases. For this reason, the drain current (that is, the collector current) is suppressed.

  On the other hand, in FIG. 12, when a positive field charge is held in the pixel electrode, the data electrode side source / drain region becomes the source (or emitter), and the pixel electrode side source / drain region becomes the drain (or collector). Become. When photoexcitation occurs in the pixel electrode side junction region which is the drain side junction region, as described above, the first current component due to the movement of electrons generated by photoexcitation and the second current component due to the bipolar effect are generated. . Here, since the source / drain region on the data line side serving as the source is connected to the data line, unlike the pixel electrode, it is not in a floating state and the potential does not change. When the second current component due to the bipolar effect is generated (that is, the base potential is lowered from the potential Lc1 to the potential Lc2, and electrons are transferred from the source / drain region on the data line side as the source to the pixel electrode source / drain region as the drain. When the electrons move, electrons flow into the pixel electrode side source / drain region in a floating state, and the potential of the pixel electrode side source / drain region as a collector increases from the potential Ld1 to the potential Ld2 (the potential decreases). ). However, unlike the above-described decrease in the potential of the pixel electrode side source / drain region as the source, the increase in the potential of the pixel electrode side source / drain region as the collector has little function of suppressing the drain current. Since the drain current (ie, collector current) is almost determined by the magnitude of the base potential with respect to the emitter potential, the drain current is hardly suppressed even if the collector potential is lowered. In other words, in the saturation region of the bipolar transistor. It is in the state.

  As described above with reference to FIGS. 11 and 12, when a positive field charge is held in the pixel electrode (that is, when the source / drain region on the pixel electrode side becomes the drain), the bipolar effect is achieved. The resulting second current component is hardly suppressed, whereas when the negative electrode charge is held in the pixel electrode (that is, when the data-side source / drain region becomes the drain), it is caused by the bipolar effect. The second current component is suppressed due to an increase in potential of the pixel electrode side source / drain region which is in a floating state. That is, when the pixel electrode side source / drain region becomes the drain, the drain current increases due to the light leakage current, compared to when the data side source / drain region becomes the drain.

  Here, FIG. 13 shows the waveform of the pixel electrode potential when relatively strong light is irradiated to the entire pixel switching TFT.

  In FIG. 13, data E2 indicates that the variation Δ1 in the pixel electrode potential when the positive charge is held in the pixel electrode (when the pixel electrode potential is the potential V1) is the negative field charge held in the pixel electrode. This indicates that it is larger than the fluctuation Δ2 of the pixel electrode potential when the pixel electrode potential is set to the potential V2. That is, it is indicated that the positive field charge is less likely to be held than the negative field charge in the pixel electrode (that is, light leakage is likely to occur). This is because when the pixel electrode holds a positive field charge (that is, when the pixel electrode side source / drain region becomes the drain), the pixel electrode holds a negative field charge (that is, This is consistent with the mechanism described above in which light leakage current is more likely to occur than when the data line side source / drain region becomes the drain.

  As described above in detail with reference to FIGS. 8 to 13, the drain current tends to increase when photoexcitation occurs in the drain side junction region in the pixel switching TFT. Further, when the pixel electrode side source / drain region becomes the drain, the drain current tends to increase (in other words, when the data line side source / drain region becomes the drain, the current component due to the bipolar effect is suppressed. ing).

  For the reason described above, in this embodiment, the pinpoint light shielding region 500 (see FIG. 4) is provided for the pixel electrode side LDD region 1c. Therefore, it is possible to form more stepped portions using the area of the pinpoint region 500. Therefore, the capacity can be increased more effectively. By increasing the capacity, the storage capacitor 70 improves the potential holding characteristics of the pixel electrode 9a, and improves display characteristics such as improving contrast and reducing flicker. That is, according to the liquid crystal device according to the present embodiment, it is possible to display a higher quality image.

Second Embodiment
Next, a liquid crystal device according to a second embodiment will be described with reference to FIGS. FIG. 14 is a plan view showing the configuration of the storage capacitor of the liquid crystal device according to the second embodiment, and FIG. 15 is a sectional view taken along line BB ′ of FIG. The second embodiment is largely different from the first embodiment described above in that the TFT 30 is a lateral transistor, and the other configurations are substantially the same. Therefore, below, a different part from 1st Embodiment is demonstrated in detail, and description shall be abbreviate | omitted suitably about the overlapping part.

  In FIG. 14, in the liquid crystal device according to the second embodiment, the TFT 30 is constituted by a lateral transistor. That is, the semiconductor layer 1a is formed so as to extend in the X direction in the drawing. Further, the relay layer 93 is formed in the same layer as the signal line 6 a, the semiconductor layer 1 a is electrically connected to the relay layer 93 through the contact hole 83, and is electrically connected to the lower electrode 71 through the contact hole 85. It is connected to the.

  In FIG. 15, the scanning line 11a is formed on the TFT array substrate 10 and also functions as the lower light-shielding film 110 in the first embodiment described above. The gate electrode 3a is formed above the scanning line 11a via the base insulating film 12 and the insulating film 202. That is, the gate electrode 3a is formed in a layer different from the scanning line 11a. Therefore, by forming contact holes 810 on both sides of the semiconductor layer 1a, the scanning line 11a and the gate electrode 3a are electrically connected. In order to form such a contact hole 810, the area of the gate electrode 3a is relatively large. That is, the area of the pinpoint light shielding region 500 is increased. Accordingly, it is possible to form more stepped portions as in the first embodiment described above.

  On the upper layer of the TFT 30, a step forming film 200 and a storage capacitor 70 are formed via an interlayer insulating film 41. The storage capacitor 70 is formed so as to straddle the step portion formed by the step forming film 200. Therefore, the storage capacitor 70 is also formed on the side wall in the step portion, and the capacitance is increased.

  As described above, even when a lateral transistor is used, the capacitance can be increased using the stepped portion as in the first embodiment described above. Therefore, a high quality image can be displayed.

<Electronic equipment>
Next, the case where the liquid crystal device which is the above-described electro-optical device is applied to various electronic devices will be described. FIG. 16 is a plan view showing a configuration example of the projector. Hereinafter, a projector using the liquid crystal device as a light valve will be described.

  As shown in FIG. 16, a projector 1100 includes a lamp unit 1102 made of a white light source such as a halogen lamp. The projection light emitted from the lamp unit 1102 is separated into three primary colors of RGB by four mirrors 1106 and two dichroic mirrors 1108 arranged in the light guide 1104, and serves as a light valve corresponding to each primary color. The light enters the liquid crystal panels 1110R, 1110B, and 1110G.

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

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

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

  In addition to the electronic device described with reference to FIG. 16, a mobile personal computer, a mobile phone, a liquid crystal television, a viewfinder type, a monitor direct view type video tape recorder, a car navigation device, a pager, and an electronic notebook , Calculators, word processors, workstations, videophones, POS terminals, devices with touch panels, and the like. Needless to say, the present invention can be applied to these various electronic devices.

  In addition to the liquid crystal devices described in the above embodiments, the present invention includes a reflective liquid crystal device (LCOS), a plasma display (PDP), a field emission display (FED, SED), an organic EL display, and a digital micromirror device. (DMD), electrophoresis apparatus and the like are also applicable.

  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, and an electro-optical device with such a change, And an electronic device provided with the same is also included in the technical scope of the present invention.

1 is a plan view illustrating a schematic configuration of a liquid crystal device according to a first embodiment. It is the HH 'sectional view taken on the line of FIG. FIG. 2 is an equivalent circuit diagram of various elements, wirings, and the like in a plurality of pixels formed in a matrix that forms an image display region of the liquid crystal device according to the first embodiment. It is. It is a top view which shows the structure of the storage capacity of the liquid crystal device which concerns on 1st Embodiment. FIG. 5 is a cross-sectional view taken along line AA ′ in FIG. 4. FIG. 5 is a sectional view taken along line CC ′ in FIG. 4. It is a top view which shows the modification of the liquid crystal device which concerns on 1st Embodiment. It is a graph which shows the relationship between the light irradiation position and drain current in TFT for a test. It is a conceptual diagram which shows the behavior of a carrier when photoexcitation generate | occur | produces in the drain side junction area | region. It is a conceptual diagram which shows the behavior of the carrier when photoexcitation occurs in the source side junction region FIG. 6 is a conceptual diagram showing the behavior of carriers when photoexcitation occurs in a data line side junction region (in other words, drain side junction region) when the data line side source / drain region is set to a drain potential. FIG. 5 is a conceptual diagram showing the behavior of carriers when photoexcitation occurs in a pixel electrode side junction region (in other words, drain side junction region) when the pixel electrode side source / drain region is at a drain potential. The waveform of the pixel electrode potential when relatively strong light is irradiated to the entire pixel switching TFT is shown. It is a top view which shows the structure of the storage capacity of the liquid crystal device which concerns on 2nd Embodiment. It is the BB 'sectional view taken on the line of FIG. It is a top view which shows the structure of the projector which is an example of the electronic device to which the electro-optical apparatus is applied.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1a ... Semiconductor layer, 1a '... Channel region, 1b ... Data line side LDD region, 1c ... Pixel electrode side LDD region, 1d ... Data line side source / drain region, 1e ... Pixel electrode side source / drain region, 2 ... Gate insulating film 3a ... Gate electrode, 6a ... Data line, 9a ... Pixel electrode, 10 ... TFT array substrate, 10a ... Image display area, 11a ... Scanning line, 30 ... TFT, 70 ... Storage capacitor, 71 ... Lower electrode, 75 ... Capacitor Insulating film, 83 ... Contact hole, 99cr ... Intersection region, 200 ... Step forming film, 210 ... Spacer insulating film, 300 ... Upper electrode, 500 ... Pinpoint light shielding region

Claims (3)

Data lines and scan lines extending across each other;
A transistor electrically connected to the data line and the scan line;
A pixel electrode provided corresponding to the transistor;
A light shielding film provided so as to cover a predetermined region of the transistor;
At least one step portion provided on the light shielding film;
A storage capacitor formed in the stepped portion;
With
The light-shielding film is formed on the pixel electrode side LDD region along a pixel electrode side LDD region disposed between a pixel electrode side source / drain region electrically connected to the pixel electrode and a channel region of the transistor . An extension portion extending to the first side and the second side, disposed in the same layer as the gate electrode of the transistor electrically connected to the scan line, and connected to the data line and the scan line Disposed at least partially inside the intersecting region of the data lines and the scanning lines as viewed from the intersecting direction;
The stepped portion is provided so that the height is different between the pixel electrode side LDD region and the extending portion, and is formed by locally laminating an insulating film so as to overlap the pixel electrode side LDD region. An electro-optical device.   The electro-optical device according to claim 1, wherein the step portion is provided in a layer above the light-shielding film that has been subjected to a planarization process.   An electronic apparatus comprising the electro-optical device according to claim 1.

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