Patent Abstract:
It is an object of the present invention to provide a display device where expansion of a frame portion over a substrate, which results from formation of a lead wiring over an active matrix substrate, is minimally suppressed to realize a narrow frame. According to one feature of a display device of the present invention, a chamfer portion is formed at least at an end portion of an active matrix substrate having a pixel portion of a pair of substrates disposed to be opposed to each other, and wirings (a source line, a gate line, a storage capacitor line, a leading out wiring, and the like) over the active matrix substrate are electrically connected by a common wiring formed in the chamfer portion.

Full Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an active matrix display device having an active matrix display portion which is structure by formation of a thin film transistor (hereinafter, referred to as a TFT) over a substrate. 
     2. Description of the Related Art 
     Conventionally, display devices typified by a liquid crystal display device and a light-emitting device have been known as active matrix display devices using active elements such as TFTs. In these active matrix display devices, pixel density can be increased. In addition, the active matrix display devices are small and lightweight, and consume low power. Accordingly, products using active matrix display devices such as a monitor for a computer, a television, and a monitor for a car navigation system have been developed as one of flat panel displays in substitution for a CRT display. 
     In addition, each of these active matrix display devices has a structure including an active matrix substrate. For example, in a case of a liquid crystal display device, display is performed in the following manner: a substrate (an active matrix substrate) provided with a pixel portion including a first electrode (a pixel electrode) and the like in addition to a plurality of TFTs and wirings and a substrate (an opposite substrate) provided with a second electrode (an opposite electrode), a light-shielding film (a black matrix), a colored film (a color filter), and the like are attached to each other; a space between these substrates is filled and sealed with a liquid crystal material; and liquid crystal molecules are oriented by an electric field which is applied between the pixel electrode and the opposite electrode to control the amount of light from a light source. 
     Note that, in the active matrix substrate, the wirings (a source line, a gate line, a storage capacitor line, and the like) formed in the pixel portion are electrically connected to lead wirings (also referred to as a common line, a ground line, or a ground line) which are formed in the periphery of the pixel portion in order to secure a function and an optimum layout of the active matrix substrate. Conventionally, these lead wirings have an advantage that the manufacturing process can be simplified because the lead wirings can be manufactured in the same process with the use of the same conductive material as the component formed in the pixel portion. 
     However, these lead wirings are long in length and wiring resistance thereof is increased even with the use of a low-resistant metal. Therefore, as compared with the wirings of the pixel portion, it is necessary to increase the width of the lead wirings. However, in order to increase the width of the lead wirings, there has been a problem that the area of a frame portion (a peripheral region over the substrate other than the pixel portion) is increased. 
     In downsizing the display device, it is important to narrow a frame thereof in order to form a panel having a large display region, and various attempts have been made (for example, see Patent Document 1: Japanese Published Patent Application No. 2000-187237). 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide a display device where expansion of a frame portion over a substrate, which results from formation of a lead wiring over an active matrix substrate, is minimized to realize a narrow frame. 
     According to one feature of a display device of the present invention, a chamfer portion is formed at least at an end portion of an active matrix substrate having a pixel portion of a pair of substrates disposed to be opposed to each other, and wirings (a source line, a gate line, a storage capacitor line, a leading out wiring, and the like) over the active matrix substrate are electrically connected by a common wiring formed in the chamfer portion. 
     According to a specific structure relating to the display device of the present invention, a display device includes at least a pair of substrates disposed to be opposed to each other; a wiring formed up to the end portion of an opposite surface of one of the pair of substrates; a chamfer portion formed at the end portion of the substrate where the wiring is formed; and a common wiring formed in the chamfer portion and vicinity thereof. In the display device, the wiring is electrically connected to the common wiring in the chamfer portion or vicinity thereof. 
     According to another structure relating to the display device of the present invention, a display device includes at least a pair of substrates each having a different area disposed to be opposed to each other; a chamfer portion, which is at the end portion of the opposite surface of the substrate having a larger area of the pair of substrates, formed in a position where the substrate having a smaller area is not overlapped; a wiring formed up to vicinity of the chamfer portion; and a common wiring formed in the chamfer portion and vicinity thereof. In the display device, the wiring is electrically connected to the common wiring in the chamfer portion or vicinity thereof. 
     According to another structure relating to the display device of the present invention, a display device includes at least a pair of substrates disposed to be opposed to each other; a plurality of thin film transistors formed over an opposite surface of one of the pair of substrates; a wiring electrically connected to at least one of the plurality of thin film transistors; a chamfer portion formed at the end portion of the substrate where the plurality of thin film transistors and the wiring are formed; and a common wiring fondled in the chamfer portion and vicinity thereof. In the display device, the wiring is electrically connected to the common wiring in the chamfer portion or vicinity thereof. 
     According to another structure relating to the display device of the present invention, a display device includes at least a pair of substrates disposed to be opposed to each other; a plurality of thin film transistors formed over an opposite surface of one of the pair of substrates; a source line electrically connected to at least one of the plurality of thin film transistors; a leading out wiring electrically connected to an external circuit; a chamfer portion formed at the end portion of the substrate where the plurality of thin film transistors, the source line, and the leading out wiring are formed; and a common wiring formed in the chamfer portion and vicinity thereof. In the display device, the source line and the leading out wiring are electrically connected to the common wiring in the chamfer portion or vicinity thereof. 
     Note that, in each of the above structures, the common wiring is formed to include a conductive material containing at least one of Ag, Au, Cu, Ni, Pt, Pd, Ir, Rh, W, Al, Ta, Mo, Cd, Zn, Fe, Ti, Si, Ge, Zr, Ba, and Nd, or indium tin oxide (ITO) or indium zinc oxide (IZO), which is a transparent conductive film. 
     In the present invention, a display device refers to a device using a liquid crystal element or a light-emitting element, namely, an image display device. In addition, the following are all included in a display device: a module in which a connector, for example, an FPC (Flexible Printed Circuit), a TAB (Tape Automated Bonding) tape, or a TCP (Tape Carrier Package) is attached to a display panel (a liquid crystal display panel or a light-emitting panel); a module provided with a printed wiring board at the end of a TAB tape or a TCP; and a module in which an IC (integrated circuit) or a CPU (central processing unit) is directly mounted on a display panel by a COG (chip on glass) method. 
     A narrow frame of a display panel can be realized because a common wiring can be formed in the end portion of the substrate in substitution for a lead wiring over an active matrix substrate so that expansion of a frame portion over the substrate can minimally be suppressed by implementation of the present invention. In addition, the common wiring of the present invention can be formed thick in film thickness in its manufacturing; therefore, it is possible to reduce wiring resistance thereof. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       In the accompanying drawings: 
         FIG. 1  is a view explaining a structure of the present invention; 
         FIGS. 2A to 2F  are views each explaining a manufacturing method of a display panel of the present invention; 
         FIGS. 3A and 3B  are views each explaining the structure of a display panel of the present invention; 
         FIG. 4  is a view explaining a structure of the present invention; 
         FIGS. 5A to 5E  are views each explaining a manufacturing method of a display panel of the present invention; 
         FIGS. 6A and 6B  are views each explaining a manufacturing method of a display panel of the present invention; 
         FIGS. 7A to 7E  are views each explaining a manufacturing method of an active matrix substrate of the present invention; 
         FIGS. 8A to 8D  are views each explaining a manufacturing method of an active matrix substrate of the present invention; 
         FIGS. 9A and 9B  are views each explaining a display panel of the present invention; 
         FIG. 10  is a view explaining a module of the present invention; and 
         FIGS. 11A to 11E  are views each explaining an electronic device. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Embodiment modes of the present invention will be explained hereinafter with reference to the accompanying drawings. However, it is to be easily understood that various changes and modifications will be apparent to those skilled in the art. Therefore, unless such changes and modifications depart from the purpose and the scope of the present invention, they should be construed as being included therein. 
     Embodiment Mode 1 
     This embodiment mode will explain a liquid crystal panel used for a liquid crystal display device as an example of a display panel used for a display device. Specifically, a liquid crystal material is sandwiched between an active matrix substrate and an opposite substrate by a One Drop Filling (ODF) method. After attaching the both substrates, an element forming surface side of the end portion of the active matrix substrate is chamfered, a common wiring is formed in a chamfer portion or the like, and wirings (a source line, a gate line, a storage capacitor line, a leading out wiring, and the like) formed over the active matrix substrate are electrically connected by the common wiring. A case having such a structure will be explained. Note that the leading out wiring is an extracted portion of the source line, a gate line, the storage capacitor line, or the like, which is formed outside the pixel portion, and which connects the pixel portion and an external circuit. 
       FIG. 1  shows a cross section of the end portion of a liquid crystal panel where a liquid crystal material  103  is sandwiched between an active matrix substrate  101  and an opposite substrate  102  and the both substrates are attached to each other with a sealant  104 . Note that, although not shown here, over a surface (an opposite surface) of the active matrix substrate  101  where the opposite substrate  102  is disposed, a wiring (a leading out wiring) or the like used so as to be connected to an external driver circuit or the like is formed, in addition to a plurality of pixel electrodes, a plurality of elements such as thin film transistors (TFTs) that form a pixel portion, and a plurality of wirings (a source line, a gate line, a storage capacitor line, and the like). The plurality of elements such as TFTs is electrically connected to the pixel electrode or the wirings (a source line, a gate line, a storage capacitor line, and the like). 
     Thus, a wiring  105  shown in  FIG. 1  shows the wirings (a source line, a gate line, a storage capacitor line, and the like) that is electrically connected to the elements such as TFTs that form the pixel portion, or the wiring (a leading out wiring) used so as to be connected to an external driver circuit or the like. The wiring  105  is formed up to the end portion of the active matrix substrate  101 . 
     In the case of Embodiment Mode 1, the area of the opposite substrate  102  is smaller than that of the active matrix substrate  101  and there is a portion where the opposite substrate  102  is not overlapped over the active matrix substrate  101  in attaching the active matrix substrate and the opposite substrate. Therefore, as shown in  FIG. 1 , the end portion of the active matrix substrate  101  can be chamfered. Note that, in order to easily form an auxiliary electrode, which will be formed later, the end portion of the surface of the opposite substrate  102 , which is opposite to the surface where the active matrix substrate  101  is disposed, may be chamfered as well. 
     In addition, a common wiring  107  formed of a conductive material is formed in the chamfered portion (hereinafter, referred to as a chamfer portion  106 ). Note that the common wiring  107  is formed so as to be electrically connected to the wiring  105  over the active matrix substrate  101  in a connection portion  108 . 
     The common wiring  107  is formed in the chamfer portion  106  as described above; therefore, the wiring pattern formed over the active matrix substrate can have a minimum shape. Accordingly, the area of a peripheral portion other than the pixel portion over the substrate can be made smaller than the conventional one (that is, a frame can be narrowed). 
     Here, a specific manufacturing method of the liquid crystal panel shown in  FIG. 1  will be explained with reference to  FIGS. 2A to 2F  and  FIGS. 3A and 3B . Note that the common reference numerals are used in  FIGS. 2A to 2F  and  FIGS. 3A and 3B . 
     First, as shown in  FIG. 2A , a plurality of active matrix substrates  203  are formed over a first substrate  201 , and the periphery of a pixel portion  204  of each active matrix substrate is coated with a sealant  205 . Then, after dropping a liquid crystal material  206  onto the region surrounded with the sealant  205 , a second substrate  202 , where a plurality of opposite substrates  207  are formed, is attached to the first substrate  201  ( FIG. 2B ). 
     Note that a known liquid crystal material can be used as the liquid crystal material  206  which is used here. 
     Next, a liquid crystal panel shown in  FIG. 2C  is obtained after separation of the attached substrates in accordance with dotted lines of  FIG. 2B . Note that the liquid crystal panel shown in  FIG. 2C  has a structure where the active matrix substrate  203  and the opposite substrate  207  are attached with the sealant  205 . 
     Then, only the opposite substrate  207  is separated from the separated liquid crystal panel in accordance with a dotted line of  FIG. 2C  to obtain a structure shown in  FIG. 2D . The area of an opposite substrate  208  that is obtained in such a manner gets smaller than that of the active matrix substrate  203 . In the liquid crystal panel shown in  FIG. 2D , a connection portion to a driver circuit is formed on two sides denoted by reference numeral  209 , and a chamfer portion is formed on the other two sides denoted by reference numeral  210  in order to form a common wiring. Note that a chamfer portion may also be formed on the sides where the connection portion to a driver circuit is formed. 
     Specifically, the sizes of the active matrix substrate and the opposite substrate are preferably made to be those shown in  FIG. 3A . In other words, in  FIG. 3A , a region a ( 209 ) including two sides where the connection portion to the driver circuit is formed is to be provided with a distance (a) from the opposite substrate  208  to the end portion of the active matrix substrate  203 , and a region b ( 210 ) including the other two sides where the connection portion to the driver circuit is not formed is to be provided with a distance (b) from the opposite substrate  208  to the end portion of the active matrix substrate  203 . Note that, in this case, the relation between the distances (a) and (b) satisfies the distance (a)&gt;the distance (b). 
     In addition,  FIG. 3B  shows a state where a chamfer portion  212  is formed in the region b ( 210 ) of the liquid crystal panel shown in  FIG. 3A , and  FIG. 2E  shows a cross-sectional view taken along a line A-A′ of  FIG. 3B . Note that, in order to form the chamfer portion  212 , a known method, for example, grinding with the use of a grindstone such as diamond or chamfer using a laser can be used. Moreover, as shown in  FIG. 2E , in the present invention, the shape of the chamfer portion  212  has an angle (θ), where a flat surface of a substrate and a flat surface where the chamfer portion  212  is formed are intersected, to be a chamfer angle, and the chamfer angle (θ) may satisfy 0°&lt;θ&lt;90° or may have a shape having a curved surface (an R surface). 
     Moreover, in forming the chamfer portion  212 , first, part of wirings  211  which are formed up to the end portion of the active matrix substrate  203  is chamfered along with the end portion of the active matrix substrate  203 . However, in order to electrically connect a common wiring formed in the subsequent step to the wiring  211 , it is necessary to leave part of the wirings  211  between the chamfer portion  212  and the end portion of the opposite substrate  208 . 
     Then, by forming common wiring  214  in a portion shown by a region c ( 213 ) of  FIG. 3B , all of the wirings  211  formed over the active matrix substrate  203  can be connected electrically. 
     Note that, as the manufacturing method of the common wiring  214 , sputtering, evaporation, droplet discharging, PVD, CVD, coating, or the like can be used, and as the conductive material used to form the common wiring  214 , for example, a metal element such as Ag, Au, Cu, Ni, Pt, Pd, Ir, Rh, W, Al, Ta, Mo, Cd, Zn, Fe, Ti, Si, Ge, Zr, Ba, or Nd, an alloy material containing the metal element as its main component, a compound material such as metal nitride containing the metal element, or a conductive material using a plurality thereof can be used. With the use of these conductive materials, the wiring resistance can be reduced. 
     In addition, indium tin oxide (ITO), indium zinc oxide (IZO) formed by using a target in which zinc oxide (ZnO) of 2 to 20 wt % is further mixed with indium oxide containing silicon oxide, or the like, which is used as a transparent conductive film, can also be used. In the case of using these materials, a light-transmitting wiring can be formed, which is effective in increasing an aperture ratio of a pixel portion. 
     Moreover, in the present invention, a conductive material for forming the common wiring  214  can be formed partially or entirely provided for the opposite substrate  208  depending on a structure of a liquid crystal panel or a property of the conductive material. In particular, in a case of an IPS (In-Plain Switching) mode liquid crystal panel, it is preferable to form the common wiring  214  so as to entirely cover the upper surface of the opposite substrate  208 . 
     Note that  FIG. 2F  shows a cross-sectional view taken along a line A-A′ of  FIG. 3B , in which the common wiring  214  is formed. As shown in  FIG. 2F , the wiring  211  is electrically connected to the common wiring  214  in a connection portion  215 . 
     Through the above, the chamfer portion is formed at the end portion of the active matrix substrate, and the common wirings, which electrically connect the wirings formed in the pixel portion or the like, are formed in the chamfer portion. Accordingly, the area of the wirings conventionally led to the peripheries of pixels can be reduced; therefore, a frame of the liquid crystal panel can be narrowed. 
     Embodiment Mode 2 
     This embodiment mode will explain a liquid crystal panel used for a liquid crystal display device as an example of a display panel used for a display device. Specifically, after attaching an active matrix substrate, an element forming surface side of the end portion which is chamfered in advance, to an opposite substrate, a liquid crystal material is sandwiched between the both substrates, a common wiring is formed in a chamfer portion or the like, and wirings (a source line, a gate line, a storage capacitor line, a leading out wiring, and the like) formed over the active matrix substrate are electrically connected by the common wiring. A case having such a structure will be explained. 
       FIG. 4  shows a cross section of the end portion of a liquid crystal panel formed by being injected with a liquid crystal material  403  after attaching an active matrix substrate  401 , which is chamfered in advance, and an opposite substrate  402  to each other with a sealant  404 . Note that, although not shown here, over a surface (an opposite surface) of the active matrix substrate  401  where the opposite substrate  402  is disposed, a wiring (a leading out wiring) or the like used so as to be connected to an external driver circuit or the like is formed, in addition to a plurality of pixel electrodes, a plurality of elements such as thin film transistors (TFTs) that form a pixel portion, and a plurality of wirings (a source line, a gate line, a storage capacitor line, and the like). The plurality of elements such as TFTs is electrically connected to the pixel electrode or the wirings (a source line, a gate line, a storage capacitor line, and the like). 
     Thus, a wiring  405  shown in  FIG. 4  shows the wirings (a source line, a gate line, a storage capacitor line, and the like) that is electrically connected to the elements such as TFTs that form the pixel portion, or the wiring (a leading out wiring) used so as to be connected to an external driver circuit or the like. The wiring  405  is formed up to the end portion of the active matrix substrate  401 . 
     In the case of Embodiment Mode 2, the case is shown, where the chamfer portion is formed at each end portion of the surfaces of the active matrix substrate  401  and the opposite substrate  402  facing to each other. However, it is not always necessary to form chamfer portions at the end portions of the both substrates, and a chamfer portion may be formed at least at the end portion of the active matrix substrate  401 . 
     In addition, a common wiring  407  formed of a conductive material is formed in the chamfered portion (hereinafter, referred to as a chamfer portion  406 ). Note that the common wiring  407  is formed so as to be electrically connected to the wiring  405  over the active matrix substrate  401  in a connection portion  408 . 
     The common wiring  407  is formed in the chamfer portion  406  as described above; therefore, the wiring pattern formed over the active matrix substrate can have a minimum shape. Accordingly, the area of a peripheral portion other than the pixel portion over the substrate can be made smaller than the conventional one (that is, a frame can be narrowed). 
     Here, a specific manufacturing method of the liquid crystal panel shown in  FIG. 4  will be explained with reference to  FIGS. 5A to 5E  and  FIGS. 6A and 6B . Note that the common reference numerals are used in  FIGS. 5A to 5E  and  FIGS. 6A and 6B . 
     First, as shown in  FIG. 5A , a plurality of active matrix substrates are formed over a first substrate  501 , and after the separation of these active matrix substrates, a plurality of active matrix substrates  503  are obtained. Note that  FIG. 6A  shows the first substrate  501  in detail. In addition, the first substrate  501  is separated like a dotted line shown in  FIG. 6A  to obtain a plurality of active matrix substrates  503  shown in  FIG. 6B . 
     In addition, a plurality of opposite substrates are formed over a second substrate  502 , and after the separation of these opposite substrates, a plurality of opposite substrates  504  are obtained. Note that the opposite substrates  504  are separated so as to have a smaller area than that of the active matrix substrate. Then, each end portion of the active matrix substrate  503  and the opposite substrate  504  is chamfered to obtain an active matrix substrate  503   a  having a chamfer portion  505  and an opposite substrate  504   a  having a chamfer portion  506 . Note that, in order to form the chamfer portions ( 505  and  506 ), a known method, for example, grinding with the use of a grindstone such as diamond or chamfer using a laser can be used. Note that, as with the explanation in Embodiment Mode 1, the shape of the chamfer portions ( 505  and  506 ) of the case of this embodiment mode also has an angle (θ), where a flat surface of a substrate and a flat surface where the chamfer portions ( 505  and  506 ) are formed are intersected, to be a chamfer angle, and the chamfer angle (θ) may satisfy 0°&lt;θ&lt;90° or may have a shape having a curved surface (an R surface). 
     Moreover, in forming the chamfer portion  505 , first, part of wirings  511  which are formed up to the end portion of the active matrix substrate  503  is chamfered along with the end portion of the active matrix substrate  503 . 
     In Embodiment Mode 2, since a connection portion to a driver circuit is formed on two sides of the active matrix substrate  503 , the chamfer portions are each formed on the other two sides of the active matrix substrate  503  and two sides of the opposite substrate corresponding thereto. 
     Next, the active matrix substrate  503   a  and the opposite substrate  504   a  are attached to each other with a sealant  507  ( FIG. 5B ). Note that the sealant  507  surrounds the pixel portion of the active matrix substrate  503   a  so that an inlet is formed, and the both substrates are disposed so that each of the chamfer portions ( 505  and  506 ) faces inside. 
     Also in the case of Embodiment Mode 2 as in the case of Embodiment Mode 1, in a region c ( 508 ) including two sides where the connection portion to the driver circuit is formed, a distance (a)&gt;0 from the opposite substrate  504   a  to the end portion of the active matrix substrate  503   a  is provided. Note that a region d ( 509 ) including the other two sides where the chamfer portion is formed is not to be provided with a distance from the opposite substrate  504   a  to the end portion of the active matrix substrate  503   a.    
     Then, as shown in  FIG. 5C , a liquid crystal material  510  is injected between the attached both substrates (the active matrix substrate  503   a  and the opposite substrate  504   a ), and a liquid crystal panel is obtained by sealing of the inlet. Note that, as the liquid crystal material  510  which is used here, a known liquid crystal material can be used. 
     In addition,  FIG. 5D  shows a cross-sectional view of the region d ( 509 ) of the liquid crystal panel after the liquid crystal injection. In the chamfer portion  505 , part of the wirings  511 , which is formed beforehand over the active matrix substrate  503   a , is chamfered along with the end portion of the active matrix substrate  503   a . With such a structure, a common wiring  512  formed that will be formed in the subsequent step and the wiring  511  can be electrically connected easily. 
     Then, as shown in  FIG. 5E , the wirings  511  formed over the active matrix substrate  503   a  can be electrically connected by formation of the common wiring  512 . Note that, as the manufacturing method of the common wiring  512  in the case of Embodiment Mode 2, a coating method is preferably used in terms of favorable processing workability in consideration of a place where the chamfer portion is formed or the like, and as the material used to form the common wiring  512 , a conductive paste material, for example, a conductive paste material such as a metal element such as Ag, Au, Cu, Ni, Pt, Pd, Ir, Rh, W, Al, Ta, Mo, Cd, Zn, Fe, Ti, Si, Ge, Zr, Ba, or Nd, or an alloy material containing the metal element as its main component is preferably used. 
     After attaching the active matrix substrate, an element forming surface side of the end portion which is chamfered in advance, to the opposite substrate, a liquid crystal material is sandwiched between the both substrates with the use of a liquid crystal injection method, and the common wiring is formed in the chamfer portion or the like. Embodiment Mode 2 explains such a case; however, a method (ODF) for attaching the active matrix substrate, an element forming surface side of the end portion which is chamfered in advance, to the opposite substrate can be used after sandwich of the liquid crystal material between the both substrates. 
     Through the above, the chamfer portion is formed at the end portion of the active matrix substrate, and the common wirings, which electrically connect the wirings formed in the pixel portion or the like, are formed in the chamfer portion. Accordingly, the area of the wirings conventionally led to the peripheries of pixels can be reduced; therefore, a frame of the liquid crystal panel can be narrowed. 
     Embodiment Mode 3 
     As the manufacturing method of the active matrix substrate that can be used for Embodiment Mode 1 or 2, this embodiment mode will particularly explain a manufacturing method of an amorphous silicon thin film transistor (TFT) and a pixel electrode formed in a pixel portion (reference numeral  204  of  FIG. 3B  and reference numeral  513  of  FIGS. 6A and 6B ) over an active matrix substrate, with reference to  FIGS. 7A to 7E  and  FIGS. 8A to 8D . Note that explanation will be given in  FIGS. 7A to 7E  and  FIGS. 8A to 8D  with the common reference numerals. 
     As shown in  FIG. 7A , a first conductive film  702  is formed over a substrate  701 . The first conductive film  702  can be formed using a film formation method such as sputtering, PVD, CVD, droplet discharging, printing, or electroplating. As the material that is used to form the first conductive film  702 , for example, a metal element such as Ag, Au, Cu, Ni, Pt, Pd, Ir, Rh, W, Al, Ta, Mo, Cd, Zn, Fe, Ti, Si, Ge, Zr, Ba, or Nd, an alloy material containing the metal element as its main component, a compound material such as metal nitride containing the metal element, or a material using a plurality thereof can be used. Since these materials are a low-resistant conductive material, the wiring resistance can be reduced. 
     In addition, as the material used to form the first conductive film  702 , indium tin oxide (ITO), indium zinc oxide (IZO) formed by using a target in which zinc oxide (ZnO) of 2 to 20 wt % is further mixed with indium oxide containing silicon oxide, or the like, which is used as a transparent conductive film, can also be used. In the case of using these materials, a light-transmitting wiring can be formed, which is effective in increasing an aperture ratio of a pixel portion. 
     A glass substrate, a quartz substrate, a substrate formed from an insulating substance such as ceramic such as alumina, a plastic substrate, a silicon wafer, a metal plate, or the like can be used for the substrate  701 . 
     Although not shown here, in order to prevent an impurity from mixing into a semiconductor film or the like from the substrate  701 , a blocking film such as a silicon nitride film, a silicon oxide film, a silicon nitride oxide film, or a stacked film thereof may be formed over the substrate  701 . 
     Next, a gate electrode  703  and a gate line  704  are formed by patterning of a first conductive film  702  ( FIG. 7B ). In a case where the first conductive film  702  is formed by a film formation method such as sputtering or CVD, a mask is formed over the conductive film by droplet discharging, a photolithography step, exposure of a photosensitive material using a laser beam direct drawing apparatus and development, or the like. Then, the conductive film is patterned into a desired shape using the mask. 
     Since the pattern can be directly formed when a droplet discharging method is used, the gate electrode  703  and the gate line  704  are formed by discharging and heating a liquid substance in which the above metal particles are dissolved or dispersed in an organic resin from an outlet (hereinafter, referred to as a nozzle). The organic resin may be one or more kinds of organic resins serving as a binder, solvent, a dispersing agent, and a coating agent of metal particles. Typically, polyimide, acrylic, a novolac resin, a melamine resin, a phenol resin, an epoxy resin, a silicon resin, a furan resin, a diallyl phthalate resin, and other known organic resins are given. 
     Note that the viscosity of the liquid substance is preferably 5 to 20 mPa·s for preventing drying and for allowing the metal particles to be discharged smoothly from the outlet. The surface tension of the liquid substance is preferably 40 mN/m or less. Note that the viscosity and the like of the liquid substance may be set appropriately in accordance with a solvent to be used or the application. 
     Although the diameter of the metal particle contained in the liquid substance may be several nm to 10 μm, it is preferably as small as possible in order to prevent a nozzle from clogging and to make high-resolution patterns. Much preferably, each metal particle has a grain diameter of 0.1 μm or less. 
     Then, an insulating film  705  is formed. The insulating film  705  is formed to have a single layer structure or a stacked layer structure of a silicon oxide film, a silicon nitride film, a silicon oxynitride film, a silicon nitride oxide film, other insulating films containing silicon, or the like by a film formation method such as CVD or sputtering. A thickness of the insulating film  705  is preferably 300 to 500 nm, and much preferably 350 to 480 nm. 
     Next, a first semiconductor film  706  is formed. The first semiconductor film  706  can be formed by a film formation method such as CVD or sputtering. The first semiconductor film  706  can be formed using any of an amorphous semiconductor film, an amorphous semiconductor film partially containing a crystalline state, and a crystalline semiconductor film, each of which contains silicon, silicon-germanium (SiGe), or the like as its main component and has a different crystalline state. In addition, the first semiconductor film  706  may also contain an acceptor element or a donor element such as phosphorus, arsenic, or boron in addition to the above main component. A thickness of the first semiconductor film  706  is preferably 40 to 250 nm, and much preferably 50 to 220 nm. 
     Then, a second semiconductor film  707  having one conductivity type is formed over the first semiconductor film  706 . The second semiconductor film  707  is formed by a film formation method such as CVD or sputtering. A film formed here such as an amorphous semiconductor film, an amorphous semiconductor film partially containing a crystalline state, or a crystalline semiconductor film, each of which contains silicon or silicon-germanium (SiGe) as its main component and has a different crystalline state, contains an acceptor element or a donor element such as phosphorus, arsenic, or boron in addition to the above main component ( FIG. 7C ). 
     As shown in  FIG. 7D , a first mask  708  is formed in a desired location over the second semiconductor film  707 , and each part of the first semiconductor film  706  and the second semiconductor film  707  is etched using the masks; therefore, a first semiconductor film  709  and a second semiconductor film  710  are obtained, respectively, which are patterned ( FIG. 7D ). Note that the first semiconductor film  709  serves as a channel formation region of a TFT  714  which will be formed in the subsequent step. 
     After removing the first mask  708 , a second conductive film  711  is formed over the second semiconductor film  710  and the insulating film  705 . Note that a thickness of the second conductive film  711  is preferably 100 nm or more, and much preferably 200 to 700 nm. As the conductive material used for the second conductive film  711 , a film formed of a metal element such as Ag, Au, Cu, Ni, Pt, Pd, Ir, Rh, W, Al, Ta, Mo, Cd, Zn, Fe, Ti, Si, Ge, Zr, or Ba, a film formed of an alloy material containing the element as its main component, a film formed of a compound material such as metal nitride, or the like can be given. 
     Second masks ( 712   a  and  712   b ) are formed over the second conductive film  711 , and part of the second conductive film  711  is etched to be formed into a desired shape. Second conductive films ( 713   a  and  713   b ) which are patterned here serve as a source electrode or a drain electrode of the TFT ( FIGS. 8A and 8B ). In order to form the second conductive film  711  into a desired shape, a method can be employed, by which a mask is formed over the second conductive film  711  by droplet discharging, a photolithography step, exposure of a photosensitive material using a laser beam direct drawing apparatus and development, or the like to etch the second conductive film  711  into a desired shape using the mask. 
     After removing the second masks ( 712   a  and  712   b ), part of the second semiconductor film  710  is etched using the patterned second conductive film ( 713   a  and  713   b ) as masks; therefore, a source region  715   a  and a drain region  715   b  of a TFT  714  are formed ( FIG. 8C ). 
     Note that, here, in the second conductive films ( 713   a  and  713   b ), a portion ( 713   a ) overlapped with the source region  715   a  is to be a source electrode  716   a , and a portion ( 713   b ) overlapped with the drain region  715   b  is to be a drain electrode  716   b.    
     Through the above, the TFT  714  including the gate electrode  703 , the insulating film  705 , the first semiconductor film (a channel formation region)  709 , the source region  715   a , the drain region  715   b , the source electrode  716   a , and the drain electrode  716   b  is formed ( FIG. 8C ). 
     Next, a protective film  717  is formed. Note that the protective film  717  is formed to have a single layer structure or a stacked layer structure of a silicon oxide film, a silicon nitride film, a silicon nitride oxide film, and a silicon oxynitride film by a film formation method such as plasma CVD or sputtering. A thickness of the protective film  717  is preferably 100 to 500 nm, and much preferably 200 to 300 nm. 
     An opening is formed in a location which is part of the protective film  717  and overlapped with the drain electrode  716   b  to form a pixel electrode  718  electrically connected to the drain electrode  716   b  in the opening ( FIG. 8D ). 
     The pixel electrode  718  can be formed using a film formation method such as sputtering, evaporation, CVD, or coating. As the material used to form the pixel electrode  718 , a transparent conductive film such as indium tin oxide (ITO), indium zinc oxide (IZO) formed by using a target in which zinc oxide (ZnO) of 2 to 20 wt % is further mixed with indium oxide containing silicon oxide, or MO containing silicon oxide as its composition can be used, and the pixel electrode  718  is formed by patterning of a conductive film formed of the above material. Note that a thickness of the pixel electrode  718  is 10 to 150 nm, and preferably 40 to 120 nm. 
     In addition, in a case of using a light-shielding substrate such as alumina, a silicon wafer, or a metal plate, as the material used to form the pixel electrode  718 , a metal element such as Ag, Au, Cu, Ni, Pt, Pd, Ir, Rh, W, Al, Ta, Mo, Cd, Zn, Fe, Ti, Si, Ge, Zr, Ba, or Nd, an alloy material containing the metal element as its main component, a compound material such as metal nitride containing the metal element, or a material using a plurality thereof can be used. 
     Through the above steps, the active matrix substrate that can be used for the present invention can be formed. In addition, such a chamfer portion that is explained in Embodiment Mode 1 or 2 is formed at the end portion of such an active matrix substrate, and a common wring is formed in the chamfer portion in substitution for the wiring formed in the periphery of the pixel portion. Accordingly, a narrower frame of a display panel than that of a conventional display panel can be realized. Note that the structure of the display panel will be explained in detail in Embodiment Mode 4. 
     Embodiment Mode 4 
     This embodiment mode will explain a structure of the liquid crystal display panel of the present invention with reference to  FIGS. 9A and 9B  by exemplification of a liquid crystal display panel.  FIG. 9A  is a top view of a liquid crystal display panel in which a liquid crystal material is sandwiched between an active matrix substrate  901  and an opposite substrate  902 .  FIG. 9B  corresponds to a cross-sectional view taken along a line A-A′ in  FIG. 9A . 
     In  FIG. 9A , a portion  905  surrounded by a dotted line is a pixel portion. This embodiment mode has a structure where the pixel portion  905  is formed in a region surrounded by a sealant  903  and a driver circuit portion is mounted outside of the liquid crystal display panel through an FPC (Flexible Printed Circuit)  923 . 
     The sealant  903  used for sealing a space between the active matrix substrate  901  and the opposite substrate  902  contains a gap material for maintaining the distance of the enclosed space. The space surrounded by the active matrix substrate  901 , the opposite substrate  902 , and the sealant  903  is filled with a liquid crystal material. 
     Next, the cross-sectional structure will be explained with reference to  FIG. 9B . The pixel portion  905  is formed over a first substrate  907  which forms the active matrix substrate  901  and includes a plurality of semiconductor elements typified by TFTs. In addition, in this embodiment mode, a source line driver circuit and a gate line driver circuit are included in the driver circuit portion mounted outside. 
     The pixel portion  905  is provided with a plurality of pixels, and a first electrode  911  as a pixel electrode is electrically connected to a driving TFT  913  through a wiring. An orientation film  915  is formed over the first electrode  911 , the driving TFT  913 , and a gate line  914 . 
     On the other hand, a second substrate  908 , which forms the opposite substrate  902 , is provided with a light-shielding film  916 , a colored layer (color filter)  917 , and a second electrode  919  as an opposite electrode. The second electrode  919  is provided with an orientation film  920 . 
     In the liquid crystal display panel shown in this embodiment mode, a portion in which a liquid crystal material  912  is sandwiched between the first electrode  911  formed over the active matrix substrate  901  and the second electrode  919  provided for the opposite substrate  902  is a liquid crystal element  910 . 
     Reference numeral  921  denotes a columnar spacer that is provided to control a distance (cell gap) between the active matrix substrate  901  and the opposite substrate  902 . The columnar spacer  921  is formed by etching of an insulating film into a desired shape. Note that a spherical spacer may be used as well. 
     Various signals and potential to be given to the pixel portion  905  are supplied from an FPC  923  through a connection wiring  922 . The connection wiring  922  and the FPC  923  are electrically connected to each other with an anisotropic conductive film or an anisotropic conductive resin  924 . Note that a conductive paste such as solder or silver paste may be used instead of the anisotropic conductive film or the anisotropic conductive resin. 
     In addition, each pixel formed in the pixel portion  905  in matrix is connected in a vertical direction or a horizontal direction by a wiring  925 . Note that, in the present invention, since a plurality of the wiring  925  over the active matrix substrate  901  are formed separately, a common wiring  926  is formed so as to be in contact with the wiring  925  to be able to electrically connect the wirings  925 . 
     Although not shown, a polarizing plate is fixed by an adhesive onto one or both of the surface of the active matrix substrate  901  and the surface of the opposite substrate  902 . Note that a retardation film may be provided additionally to the polarizing plate. 
     The liquid crystal display panel explained through the above is formed with the use of the active matrix substrate where the common wiring is formed in the chamfer portion in substitution for the wirings formed in the periphery of the pixel portion as explained in Embodiment Mode 1 or 2. Therefore, a narrower frame of a display panel than that of a conventional display panel can be realized. 
     Embodiment Mode 5 
     This embodiment mode will explain a module formed by connection of an external circuit such as a power supply circuit or a controller to a liquid crystal display panel (a liquid crystal module here), which is exemplified as the display panel of the present invention formed by implementation of Embodiment Modes 1 to 4, which displays color images using white light, with reference to a cross-sectional view of  FIG. 10 . 
     As shown in  FIG. 10 , an active matrix substrate  1001  and an opposite substrate  1002  are firmly fixed by a sealant  1003 , and a liquid crystal material  1005  is provided between the active matrix substrate  1001  and the opposite substrate  1002 ; therefore, a liquid crystal display panel is formed. 
     Note that a chamfer portion of the active matrix substrate  1001  is formed by chamfering of an end portion thereof. Then, a common wiring  1021  is formed in the chamfer portion so as to be in contact with a wiring  1020  for electrically connecting a plurality of pixels formed in a pixel portion of the active matrix substrate  1001 . 
     A colored film  1006  formed over the active matrix substrate  1001  is required in order to display color images. In a case of the RGB system, a colored film corresponding to each color of red, green, and blue is provided corresponding to each pixel. Orientation films  1018  and  1019  are formed inside the active matrix substrate  1001  and the opposite substrate  1002 . In addition, polarizing plates  1007  and  1008  are provided outside the active matrix substrate  1001  and the opposite substrate  1002 . A protective film  1009  is formed on the surface of the polarizing plate  1007  to reduce the external impact. 
     A connection terminal  1010  provided over the active matrix substrate  1001  is connected to a wiring board  1012  through an FPC  1011 . The wiring board  1012  includes an external circuit  1013  such as a pixel driver circuit (an IC chip, a driver IC, or the like), a control circuit, or a power supply circuit. 
     A back light unit includes a cold cathode tube  1014 , a reflecting plate  1015 , an optical film  1016 , and an inverter (not shown), which functions as a light source to emit light to the liquid crystal display panel. The liquid crystal display panel, the light source, the wiring board  1012 , the FPC  1011 , and the like are held and protected by a bezel  1017 . 
     The module shown through the above includes the display panel using the active matrix substrate, the frame of which is narrowed, by formation of the common wiring in the chamfer portion in substitution for the wirings formed in the periphery of the pixel portion as explained in Embodiment Mode 4. Therefore, even in the case of forming the module, a smaller size (a narrowed frame) can be realized as compared with the conventional case. 
     Embodiment Mode 6 
     As electronic devices provided with the display device of the present invention, a television device (also simply referred to as a television or a television receiver), a camera such as a digital camera or a digital video camera, a telephone device (also simply referred to as a telephone set or a telephone), an information terminal such as a PDA, a game machine, a monitor for computer, a computer, an audio reproducing device such as a car audio system or an MP3 player, an image reproducing device provided with a recording medium, such as a home-use game machine, and the like are given. Preferred modes thereof will be explained with reference to  FIGS. 11A to 11E . 
     A television device shown in  FIG. 11A  includes a main body  8001 , a display portion  8002 , and the like. The display device of the present invention can be applied to the display portion  8002 . Note that, as the display device of the present invention, a display panel including an active matrix substrate, the frame of which is narrowed, is used by formation of a chamfer portion at the end portion of the substrate and formation of a common wiring in the chamfer portion in substitution for the wirings conventionally formed in the periphery of the pixel portion. Accordingly, it is possible to provide a television device, the size of which is made smaller (the frame of which is narrowed) and the wiring resistance of which is reduced as compared with a conventional television device. 
     An information terminal device shown in  FIG. 11B  includes a main body  8101 , a display portion  8102 , and the like. The display device of the present invention can be applied to the display portion  8102 . Note that, as the display device of the present invention, a display panel including an active matrix substrate, the frame of which is narrowed, is used by formation of a chamfer portion at the end portion of the substrate and formation of a common wiring in the chamfer portion in substitution for the wirings conventionally formed in the periphery of the pixel portion. Accordingly, it is possible to provide an information terminal device, the size of which is made smaller (the frame of which is narrowed) and the wiring resistance of which is reduced as compared with a conventional information terminal device. 
     A digital video camera shown in  FIG. 11C  includes a main body  8201 , a display portion  8202 , and the like. The display device of the present invention can be applied to the display portion  8202 . Note that, as the display device of the present invention, a display panel including an active matrix substrate, the frame of which is narrowed, is used by formation of a chamfer portion at the end portion of the substrate and formation of a common wiring in the chamfer portion in substitution for the wirings conventionally formed in the periphery of the pixel portion. Accordingly, it is possible to provide a digital video camera, the size of which is made smaller (the frame of which is narrowed) and the wiring resistance of which is reduced as compared with a conventional digital video camera. 
     A telephone set shown in  FIG. 11D  includes a main body  8301 , a display portion  8302 , and the like. The display device of the present invention can be applied to the display portion  8302 . Note that, as the display device of the present invention, a display panel including an active matrix substrate, the frame of which is narrowed, is used by formation of a chamfer portion at the end portion of the substrate and formation of a common wiring in the chamfer portion in substitution for the wirings conventionally formed in the periphery of the pixel portion. Accordingly, it is possible to provide a telephone set, the size of which is made smaller (the frame of which is narrowed) and the wiring resistance of which is reduced as compared with a conventional digital video camera. 
     A liquid crystal monitor shown in  FIG. 11E  includes a main body  8401 , a display portion  8402 , and the like. The display device of the present invention can be applied to the display portion  8402 . Note that, as the display device of the present invention, a display panel including an active matrix substrate, the frame of which is narrowed, is used by formation of a chamfer portion at the end portion of the substrate and formation of a common wiring in the chamfer portion in substitution for the wirings conventionally formed in the periphery of the pixel portion. Accordingly, it is possible to provide a liquid crystal monitor, the size of which is made smaller (the frame of which is narrowed) and the wiring resistance of which is reduced as compared with a conventional liquid crystal monitor. 
     A display device includes an active matrix substrate, the frame of which is narrowed, is used by formation of a common wiring in the chamfer portion, which is formed at the end portion of the substrate, in substitution for the wirings formed in the periphery of the pixel portion. With the use of the display device for a display portion thereof, it is possible to provide an electronic device, the size of which is made smaller (the frame of which is narrowed) as compared with a conventional electronic device. 
     The present application is based on Japanese Patent Application serial No. 2006-021722 filed on Jan. 31, 2006 in Japanese Patent Office, the entire contents of which are hereby incorporated by reference.

Technology Classification (CPC): 6