(19) United States
`(12) Patent Application Publication (10) Pub. No.: US 2005/0105034 A1
`(43) Pub. Date:
`May 19, 2005
`Ono et al.
`
`US 2005O105034A1
`
`(54) LIQUID CRYSTAL DISPLAY DEVICE
`(76) Inventors: Kikuo Ono, Mobara (JP); Ikuko Mori,
`Chiba (JP); Ryutaro Oke, Mobara (JP);
`Hiroyuki Yarita, Mobara (JP)
`Correspondence Address:
`ANTONELLI, TERRY, STOUT & KRAUS,
`LLP
`1300 NORTH SEVENTEENTH STREET
`SUTE 1800
`ARLINGTON, VA 22209-9889 (US)
`(21) Appl. No.:
`10/991,380
`(22) Filed:
`Nov. 19, 2004
`(30)
`Foreign Application Priority Data
`
`Nov. 19, 2003 (JP)...................................... 2003-389024
`
`Publication Classification
`
`(51) Int. Cl." ............................................. G02F 1/1343
`(52) U.S. Cl. ............................................ 349/143; 349/141
`(57)
`ABSTRACT
`In a liquid crystal display device including a pair of Sub
`Strates which face each other with a liquid crystal layer
`disposed therebetween, a plurality of pixel regions which are
`formed on one Substrate, a planar counter electrode which is
`formed on each pixel region, and a comb-shaped or slit
`shaped pixel electrode which is formed on each pixel region,
`the comb-shaped or Slit-shaped pixel electrode being formed
`over the counter electrode by way of an insulation layer, a
`notch or a slit is formed in the counter electrode Such that a
`wiring layer made of an opaque material which transmits a
`potential to the pixel electrode from a thin film transistor
`defines a region where the wiring layer is not overlapped
`relative to the counter electrode.
`
`
`
`Page 1 of 23
`
`Tianma Exhibit 1007
`
`

`

`Patent Application Publication May 19, 2005 Sheet 1 of 11
`
`US 2005/0105034 A1
`
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`Page 2 of 23
`
`

`

`Patent Application Publication May 19, 2005 Sheet 2 of 11
`FIG 2
`
`US 2005/0105034 A1
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`Page 3 of 23
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`

`

`Patent Application Publication May 19, 2005 Sheet 3 of 11
`
`US 2005/0105034 A1
`
`FIG, 3
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`Page 4 of 23
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`

`

`Patent Application Publication May 19, 2005 Sheet 4 of 11
`
`US 2005/0105034 A1
`
`FIG. 4
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`Page 5 of 23
`
`

`

`Patent Application Publication May 19, 2005 Sheet 5 of 11
`
`US 2005/0105034 A1
`
`FIG. 6
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`Page 6 of 23
`
`

`

`Patent Application Publication May 19, 2005 Sheet 6 of 11
`
`US 2005/0105034 A1
`
`FIG. 7
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`Page 7 of 23
`
`

`

`Patent Application Publication May 19, 2005 Sheet 7 of 11
`
`US 2005/0105034 A1
`
`
`
`Page 8 of 23
`
`

`

`Patent Application Publication May 19, 2005 Sheet 8 of 11
`
`US 2005/0105034 A1
`
`FIG. 9
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`Page 9 of 23
`
`

`

`Patent Application Publication May 19, 2005 Sheet 9 of 11
`
`US 2005/0105034 A1
`
`FIG 11
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`Page 10 of 23
`
`

`

`Patent Application Publication May 19, 2005 Sheet 10 of 11
`
`US 2005/0105034 A1
`
`FIG, 12
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`Page 11 of 23
`
`

`

`Patent Application Publication May 19, 2005 Sheet 11 of 11
`
`US 2005/0105034 A1
`
`FIG. 13
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`POL2
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`Page 12 of 23
`
`

`

`US 2005/0105034 A1
`
`May 19, 2005
`
`LIQUID CRYSTAL DISPLAY DEVICE
`
`BACKGROUND OF THE INVENTION
`0001. The present invention relates in general to a liquid
`crystal display device, and, more particularly, the invention
`relates to a liquid crystal display device in which pixel
`electrodes and counter electrodes are formed on a liquid
`crystal-Surface Side of one Substrate of respective Substrates
`which are arranged to face each other with liquid crystal
`disposed therebetween.
`0002 Recently, consideration has been given to a liquid
`crystal display device having a constitution in which a
`counter electrode, which is formed as a transparent elec
`trode, is formed over the whole area of a pixel region, except
`for a periphery of the pixel region, and Strip-like pixel
`electrodes formed as transparent electrodes, which extend in
`one direction and are arranged in parallel in a direction
`which intersects the one direction, are formed over the
`counter electrode by way of an insulation film.
`0.003 Such a liquid crystal display device is disclosed in
`Japanese Unexamined Patent Publication Hei 11(1999)-
`202356 and the corresponding U.S. Pat. No. 6,233,034.
`
`SUMMARY OF THE INVENTION
`0004. However, in Such a liquid crystal display device,
`the counter electrode, which is formed in a region other than
`the slight periphery of the pixel region, is overlapped
`relative to the comb-shaped pixel electrode formed by way
`of the insulation film with a large Overlapped area. Accord
`ingly, when pin holes are formed in the insulation film, a
`Short-circuiting failure occurs, and this becomes a point
`defect on a display, whereby the quality of the image is
`lowered.
`0005 Further, in the above-mentioned pixel region, the
`pixel electrode and a thin film transistor to be connected with
`the pixel electrode are arranged on different insulation films
`by way of respective insulation films, and, hence, contact
`holes having large areas become necessary at connecting
`portions, thus giving rise to a drawback in that the numerical
`aperture, that is, the transmissivity of the liquid crystal
`display device, is lowered. Further, in adopting a constitu
`tion in which a signal is Supplied to respective counter
`electrodes using counter electrode lines which are formed of
`an opaque metal material having a Small electrical resistiv
`ity, when the width of the counter electrode lines is large,
`there arises a drawback in that the transmissivity is lowered
`in the same manner.
`0006 Further, portions where the above-mentioned con
`tact holes are formed increase the Stepped portions thereof;
`and, hence, when an orientation film is formed over the
`portions and rubbing is applied to the orientation film, a
`region in which the liquid crystal orientation is disturbed
`Substantially along the rubbing direction is formed, thus
`giving rise to a drawback in that the transmissivity is
`lowered.
`0007. The present invention has been made in view of
`Such circumstances, and it is an object of the present
`invention to provide a liquid crystal display device in which
`Short circuiting between a pixel electrode and a counter
`electrode can be obviated, thus enhancing the image quality.
`
`0008 Further, it is another object of the present invention
`to provide a liquid crystal display device in which the
`numerical aperture is enhanced.
`0009 Still further, it is another object of the present
`invention to provide a liquid crystal display device in which
`disturbance of the liquid crystal orientation around periph
`eries of contact holes can be obviated.
`0010 Representative examples of the present invention
`disclosed in this specification are as follows.
`0011 (1) A liquid crystal display device according to the
`present invention includes a pair of Substrates which are
`arranged to face each other with liquid crystal disposed
`therebetween, a plurality of pixel regions which are formed
`on a liquid-crystal-Side Surface of the Substrate, a pixel
`electrode which is formed in each pixel region and to which
`a video signal is Supplied through a Switching element
`driven in response to a signal from a gate Signal line, and a
`counter electrode which is formed in each pixel region, is
`connected with a counter Voltage Signal line and generates
`an electric field between the pixel electrode and the counter
`electrode, wherein the counter electrode has a. planer-like
`shape in the pixel region, a wiring layer which connects the
`Switching element and the pixel electrode and extends into
`the region where the counter electrode is formed, the pixel
`electrode is formed on an upper Surface of a insulation film
`which is formed Such that the insulation film also covers the
`Switching element and the wiring layer, and Strip-like elec
`trodes or slits are formed in parallel in the direction which
`intersects the extending direction of the Strip-like electrodes
`or slits, and the connection between the wiring layer and the
`pixel electrode is established through a through hole formed
`in the second insulation film and the slits which obviate the
`counter electrode from being overlapped to the wiring layer
`are formed in the counter electrode.
`0012 (2) The liquid crystal display device according to
`the present invention is, for example, on the premise of the
`constitution (1), characterized in that the counter Voltage
`Signal line is arranged to traverse the pixel region, and a
`through hole which connects the wiring layer and the pixel
`electrode is positioned above the counter Voltage Signal line.
`0013 (3) The liquid crystal display device according to
`the present invention is, for example, on the premise of the
`constitution (1), characterized in that the initial orientation
`direction of the liquid crystal is parallel to the gate Signal
`line.
`0014 (4) The liquid crystal display device according to
`the present invention is, for example, on the premise of the
`constitution (2), characterized in that the initial orientation
`direction of the liquid crystal is parallel to the counter
`Voltage Signal line.
`0015 (5) The liquid crystal display device according to
`the present invention is, for example, on the premise of the
`constitution (3), characterized in that the extending direction
`of the Strip-like electrodes or Slits in the pixel electrode is at
`an angle of 3 to 20 degrees with respect to the gate Signal
`line in the clockwise direction or an angle of 3 to 20 degrees
`with respect to the gate Signal line in the counter-clockwise
`direction.
`0016 (6) Aliquid crystal display device according to the
`present invention includes, for example, a pair of Substrates
`
`Page 13 of 23
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`

`

`US 2005/0105034 A1
`
`May 19, 2005
`
`which face each other with a liquid crystal layer disposed
`therebetween, a plurality of pixel regions which are formed
`on one Substrate, a planar counter electrode which is formed
`on each pixel region, and a comb-shaped or Slit-shaped pixel
`electrode which is formed on each pixel region, the comb
`shaped or Slit-shaped pixel electrode being formed over the
`counter electrode by way of an insulation layer, wherein a
`notch or a slit is formed in the counter electrode Such that a
`wiring layer made of an opaque material which transmits a
`potential to the pixel electrode from a thin film transistor
`defines a region where the wiring layer is not overlapped to
`the counter electrode.
`0017 (7) The liquid crystal display device according to
`the present invention is, for example, on the premise of the
`constitution (6), characterized in that the counter electrode is
`a transparent electrode.
`0018 (8) The liquid crystal display device according to
`the present invention is, for example, on the premise of the
`constitution (7), characterized in that the pixel electrode is a
`transparent electrode.
`0019 (9) The liquid crystal display device according to
`the present invention is, for example, on the premise of the
`constitution (8), characterized in that the wiring layer and
`the pixel electrode are connected with each other via a
`through hole formed in the insulation film which covers the
`wiring layer.
`0020 (10) The liquid crystal display device according to
`the present invention is, for example, on the premise of the
`constitution (9), characterized in that the liquid crystal
`display device includes a counter Voltage Signal line which
`is connected with the counter electrode, the counter Voltage
`Signal line is arranged to traverse the pixel region, and a
`through hole which connects the wiring layer and the pixel
`electrode is positioned above the counter Voltage Signal line.
`0021 (11) The liquid crystal display device according to
`the present invention is, for example, on the premise of the
`constitution (6), characterized in that the initial orientation
`direction of the liquid crystal is parallel to the gate Signal
`line.
`0022 (12) The liquid crystal display device according to
`the present invention is, for example, on the premise of the
`constitution (10), characterized in that the initial orientation
`direction of the liquid crystal is parallel to the counter
`Voltage Signal line.
`0023 (13) Aliquid crystal display device according to the
`present invention includes, for example, a pair of Substrates
`which face each other with a liquid crystal layer disposed
`therebetween, a plurality of pixel regions which are formed
`on one Substrate, a planar counter electrode which is formed
`on each pixel region, and a comb-shaped or Slit-shaped pixel
`electrode which is formed on each pixel region, the comb
`shaped or Slit-shaped pixel electrode being formed over the
`counter electrode by way of an insulation layer, wherein the
`planar counter electrode has a removal region at a portion
`thereof, and the removal region extends in a direction which
`is different from the extending direction of the comb teeth or
`the slits of the pixel electrode.
`0024 (14) The liquid crystal display device according to
`the present invention is, for example, on the premise of the
`
`constitution (13), characterized in that the removal region
`extends in a direction parallel to a long Side of the counter
`electrode.
`0025 (15) The liquid crystal display device according to
`the present invention is, for example, on the premise of the
`constitution (13), characterized in that a wiring layer which
`is different from both of counter electrode and the pixel
`electrode is arranged in the removal region.
`0026 (16) The liquid crystal display device according to
`the present invention is, for example, on the premise of the
`constitution (14), characterized in that a wiring layer which
`is different from both of counter electrode and the pixel
`electrode is arranged in the removal region.
`0027 (17) The liquid crystal display device according to
`the present invention is, for example, on the premise of the
`constitution (16), characterized in that the counter electrode
`is formed of a transparent electrode.
`0028 (18) The liquid crystal display device according to
`the present invention is, for example, on the premise of the
`constitution (17), characterized in that the pixel electrode is
`formed of a transparent electrode.
`0029 (19) The liquid crystal display device according to
`the present invention is, for example, on the premise of the
`constitution (18), characterized in that the wiring layer and
`the pixel electrode are connected with each other via a
`through hole formed in an insulation film which covers the
`wiring layer.
`0030 (20) The liquid crystal display device according to
`the present invention is, for example, on the premise of the
`constitution (19), characterized in that the initial orientation
`direction of the liquid crystal is parallel to a short-side
`direction of the counter electrode.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`0031
`FIG. 1 is a plan view showing one embodiment of
`a pixel region of a liquid crystal display device according to
`the present invention;
`0032 FIG. 2 is an equivalent circuit diagram showing
`one embodiment of the liquid crystal display device accord
`ing to the present invention;
`0033 FIG. 3 is a cross-sectional view taken along a line
`I(a)-I(b) in FIG. 1;
`0034 FIG. 4 is a diagram showing the polarization
`behavior of liquid crystal molecules in the first embodiment;
`0035 FIG. 5 is a cross-sectional view taken along a line
`II(a)-II(b) in FIG. 1;
`0036 FIG. 6 is a cross-sectional view taken along a line
`III(a)-III(b) in FIG. 1;
`0037 FIG. 7 is a cross-sectional view taken along a line
`IV(a)-IV(b) in FIG. 1;
`0038 FIG. 8 is a plan view showing another embodiment
`of a pixel region of a liquid crystal display device according
`to the present invention;
`0039 FIG. 9 is an equivalent circuit diagram showing
`another embodiment of the liquid crystal display device
`according to the present invention;
`
`Page 14 of 23
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`

`

`US 2005/0105034 A1
`
`May 19, 2005
`
`0040 FIG. 10 is timing chart showing another embodi
`ment in driving the liquid crystal display device according to
`the present invention;
`0041
`FIG. 11 is a cross-sectional view taken along a line
`V(a)-V(b) in FIG.8;
`0.042
`FIG. 12 is a cross-sectional view taken along a line
`VI(a)-VI(b) in FIG. 8; and
`0.043
`FIG. 13 is a cross-sectional view taken along a line
`VII(a)-VII(b) in FIG. 8.
`
`DETAILED DESCRIPTION
`0044 Preferred embodiments of the liquid crystal display
`device of the present invention will be explained hereinafter
`in conjunction with the drawings.
`
`EMBODIMENT 1.
`FIG. 2 shows an equivalent circuit of a liquid
`004.5
`crystal display panel representing one embodiment of the
`present invention, together with an externally mounted
`circuit of the liquid crystal display panel.
`0046. In FIG. 2, to respective gate signal lines GL, which
`extend in the X direction and are arranged in parallel in the
`y direction, a Scanning signal (a Voltage signal) is Sequen
`tially Supplied by a vertical Scanning circuit V.
`0047. A thin film transistor TFT of each one of the pixel
`regions, which are arranged along the gate Signal lines GL
`to which the Scanning Signal is Supplied, is turned on in
`response to the Scanning Signal.
`0.048. Then, in conformity with this timing, a video signal
`is Supplied to the respective drain Signal lines DL from a
`Video signal drive circuit H. The respective drain Signal lines
`DL, as Seen in the drawing, extend in the y direction and are
`arranged in parallel in the X direction. The Video signal is
`applied to respective pixel electrodes PX through the thin
`film transistors of the respective pixel regions.
`0049 Further, a power source is supplied to the vertical
`Scanning circuit V and the Video signal drive circuit H from
`a power Source Supply PS, while a control Signal is Supplied
`to the vertical Scanning circuit V and the Video Signal drive
`circuit H from a controller TCON.
`0050. In each pixel region, a counter voltage is supplied
`to a counter electrode CT which is formed together with the
`pixel electrode PX through a counter Voltage Signal line CL,
`and an electric field is generated between the respective
`electrodes. With respect to the pixel electrode PX and the
`counter electrode CT, at the timing at which an ON voltage
`is applied to the gate Signal lines GL, the thin film transistor
`TFT is turned on and the video information voltage from the
`drain signal line DL is applied to the pixel electrode PX,
`while the counter Voltage Signal is transmitted to the counter
`electrode CT in each pixel region through the counter
`Voltage Signal line CL, which is connected with the external
`power Source, and, hence, the Voltage is applied to the liquid
`crystal capacitance. The above-mentioned pixel electrodes
`PX and the counter electrodes CT are formed on a first
`transparent substrate SUB1 on which the thin film transistors
`TFT are formed. The pixel electrode PX and the counter
`electrode CT form a pixel capacitance which is a Sum of a
`holding capacitive element Cstg, which is produced by
`
`Sandwiching an insulation film between the pixel electrode
`PX and the counter electrode CT, and a liquid crystal
`capacitance Clc, which is provided by allowing an electric
`field between the pixel electrode PX and the counter elec
`trode CT to pass through a liquid crystal portion. The liquid
`crystal mode of the present invention is characterized in that
`the area in which the counter electrode CT and the pixel
`electrode PX are stacked with an insulation film Sandwiched
`therebetween is large, and, hence, the holding capacitance
`element Cstg of one pixel assumes a large value.
`0051. Then, among these electric fields, in response to an
`electric field having components parallel to the transparent
`substrate SUB1, the optical transmissivity of the liquid
`crystal LC is controlled.
`0052 Here, as seen in the drawing, respective symbols R,
`G, B in the respective pixel regions indicate that a red color
`filter, a green color filter and a blue color filter are respec
`tively formed in the respective pixel regions.
`0053. In the above-mentioned structure, one pixel region
`is a region which is Surrounded by neighboring drain Signal
`lines DL and neighboring gate Signal lines GL, and, as
`mentioned above, the thin film transistor TFT, the pixel
`electrode PX and the counter electrode CT are formed on the
`region.
`0054. On the other hand, the counter voltage signal lines
`CL constitute lines extending in the lateral direction which
`are formed on the first transparent substrate SUB1 and are
`arranged parallel to the gate Signal line GL and are collected
`outside the pixel region where they are connected with an
`external power Source.
`0055 FIG. 1 shows a pixel region of the liquid crystal
`display device (panel) according to the present invention,
`and it is a plan view of one transparent Substrate of respec
`tive transparent Substrates which are arranged to face each
`other with liquid crystal disposed therebetween, as viewed
`from a liquid crystal side of the transparent Substrate.
`0056 FIG. 3 is a cross-sectional view taken along a line
`I(a)-I(b) in FIG. 1, FIG. 5 is a cross-sectional view taken
`along a line II(a)-II(b) in FIG. 1, FIG. 6 is a cross-sectional
`view taken along a line III(a)-III(b) in FIG. 1, and FIG. 7
`is a cross-sectional view taken along a line IV(a)-IV(b) in
`FIG. 1. FIG. 4 is a plan view showing the operation of
`liquid crystal molecules at the time of turning the Voltage
`applied to the liquid crystal molecules on or off in this liquid
`crystal mode.
`0057 First of all, in FIG. 1, the gate signal lines GL,
`which extend in the X direction and are arranged in parallel
`in the y direction in the drawing, are formed of a three
`layered stacked film formed of molybdenum (Mo), alumi
`num (Al), molybdenum (Mo), which are stacked from the
`first transparent Substrate Side, for example. This gate Signal
`line GL forms a rectangular region with the drain Signal line
`DL, which will be explained later, and this region is con
`figured to form the pixel region.
`0058. In this pixel region, the counter electrode CT is
`formed, which generates an electric field between the
`counter electrode CT and the pixel electrode PX to be
`described later. The counter electrode CT is formed to cover
`the whole area of the pixel region, except for a slight
`periphery of the pixel region, and it is made of ITO (Indium
`
`Page 15 of 23
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`

`

`US 2005/0105034 A1
`
`May 19, 2005
`
`Tin-Oxide), for example, which is a transparent conductor.
`Here, the counter electrode CT is partially notched, although
`this constitution will be explained later.
`0059) The counter electrode CT is connected with the
`counter Voltage Signal line CL, which is arranged parallel to
`the above-mentioned gate Signal line GL in the vicinity of
`Substantially the center of the neighboring gate Signal line
`GL. The counter Voltage Signal line CL is integrally formed
`with the counter Voltage Signal lines CL, which are formed
`in the same manner in the counter electrodes CT in the left
`and right pixel regions as seen in the drawing (the respective
`pixel regions which are arranged along the gate Signal lines
`GL).
`0060. The counter voltage signal line CL is formed of an
`opaque material in the form of a three-layered Stacked film
`made of molybdenum (Mo), aluminum (Al) and molybde
`num (Mo), for example.
`0061
`Further, as mentioned above, by setting the mate
`rial of the counter Voltage Signal line CL equal to the
`material of the gate Signal line GL, the counter Voltage
`Signal line CL and the gate Signal line GL can be formed in
`the same Step, and, hence, the increase of the manufacturing
`man-hours can be obviated.
`0.062
`Here, it is needless to say that the above-mentioned
`counter Voltage Signal line CL is not limited to the above
`mentioned three-layered film, and it may be formed of a
`Single-layered film made of Cr, Ti, Mo, for example, or a
`two-layered film or a three-layered film made of these
`materials and a material which contains Al.
`0.063 However, in this case, it is advantageous to position
`the counter Voltage Signal line CL above the counter elec
`trode CT. This is because a Selective etchant (for example,
`HBr) for the ITO film which constitutes the counter elec
`trode CT can easily melt Al.
`0064.
`Further, it is advantageous to interpose a high
`melting-point metal, such as Ti, Cr, Mo, Ta, W or the like,
`in at least a contact Surface between the counter Voltage
`signal line CL and the counter electrode CT. This is because
`ITO, which constitutes the counter electrode CT, oxidizes Al
`in the counter Voltage Signal line CL and forms a high
`resistance layer.
`0065 Accordingly, as one embodiment, in forming the
`counter Voltage Signal line CL made of Al or a material
`containing Al, it is preferable to adopt a multi-layered
`Structure which uses the above-mentioned high melting
`point metal as the first layer.
`0.066
`Further, on an upper surface of the transparent
`Substrate on which the counter electrode CT, the counter
`Voltage Signal line CL and the gate Signal line GL are
`formed, an insulation film GI made of SiN, for example, is
`formed Such that the insulation film GI covers the counter
`electrode CT, the counter Voltage Signal line CL and the gate
`Signal line GL.
`0067. The insulation film GI functions as an interlayer
`insulation film of the counter Voltage Signal line CL and the
`gate Signal line GL with respect to the drain Signal line DL
`to be described later; it functions as a gate insulation film of
`the thin film transistor TFT to be described later in a region
`where the thin film transistor TFT is formed; and it functions
`
`as a dielectric film of the capacitive element Cstg to be
`described later in a region where the capacitive element Cstg
`is formed.
`0068. Then, the thin film transistor TFT is formed on a
`portion of the gate signal line GL (a left lower portion in the
`drawing) in an overlapped manner, and a semiconductor
`layer AS made of a-Si, for example, is formed on the
`insulation film GI of the portion.
`0069. By forming a drain electrode SD1 and a source
`electrode SD2 on an upper Surface of the Semiconductor AS,
`it is possible to form an MIS type transistor having an
`inversely staggered Structure, which adopts a portion of the
`gate Signal line GL as a gate electrode. Here, the drain
`electrode SD1 and the Source electrode SD2 are simulta
`neously formed with the drain signal line DL.
`0070 That is, the drain signal lines DL, which extend in
`they direction and are arranged in the X direction in FIG. 1,
`are formed, and portions of the drain Signal lines DL are
`extended on the surface of the semiconductor layer AS of the
`thin film transistor TFT, thus forming the drain electrodes
`SD1 of the thin film transistors TFT.
`0071. Further, at the time of forming the drain signal lines
`DL, the Source electrodes SD2 are formed, wherein these
`Source electrodes SD2 are extended into the inside of the
`pixel regions So that contact holes CN, which are provided
`for connecting the pixel electrodes PX to be described later,
`are also integrally formed.
`0072 Here, as shown in FIG. 5, on an interface between
`the above-mentioned source electrode SD2 and the drain
`electrode SD1 of the semiconductor layer AS, a contact layer
`d0, which is doped with n-type impurities, for example, is
`formed.
`0073. The contact layer d0 is formed such that an n-type
`impurity doping layer is formed over the whole area of a
`Surface of the Semiconductor layer AS, the Source electrode
`SD2 and the drain electrode SD1 are formed, and, thereafter,
`using these respective electrodes as masks, the n-type impu
`rity doping layer, which is formed on a Surface of the
`Semiconductor layer AS that is exposed from the respective
`electrodes, is etched.
`0074 Then, on the surface of the transparent substrate
`SUB1 on which the thin film transistors TFT are formed in
`such a manner, a protective film PAS made of SiN, for
`example, is formed such that the protective film PAS also
`covers the thin film transistor TFT. The protective film PS is
`provided for preventing direct contact of the thin film
`transistor TFT with the liquid crystal LC.
`0075) Further, on an upper surface of the protective film
`PAS, the pixel electrodes PX are formed using a transparent
`conductive film made of ITO (Indium-Tin-Oxide), for
`example.
`0076) The pixel electrodes PX are formed in an over
`lapped manner on the region where the counter electrode CT
`is formed. The pixel electrodes PX extend at an equal
`interval while, respectively making an angle of approxi
`mately 10 degrees with respect to the X direction as Seen in
`the drawing, and, at the same time, both ends of the pixel
`electrodes PX are connected with each other using the same
`material layers which extend in the y direction.
`
`Page 16 of 23
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`US 2005/0105034 A1
`
`May 19, 2005
`
`0077. In this embodiment, an interval L between neigh
`boring pixel electrodes PX is set to 3 to 10 tim, for example,
`while the width w of the pixel electrode PX is set to a value
`which falls within a range of 2 to 6 um, for example.
`0078. In this case, the same material layers of the respec
`tive pixel electrodes PX at lower ends thereof are connected
`with contact portions of the source electrodes SD2 of the
`thin film transistors TFT through contact holes formed in the
`protective films PAS. On the other hand, the same material
`layer of the pixel electrodes PX1 at upper ends thereof is
`formed so as to be overlapped with the counter electrode CT.
`0079. By adopting such a constitution, on portions where
`the counter electrode CT and the respective pixel electrodes
`PX are overlapped relative to each other, a capacitive
`element Cstg, which consists of a Stacked layer film consti
`tuted of the gate insulation film GI and the protective film
`PAS as a dielectric film, is formed.
`0080. The capacitive element Cstg is provided for storing
`the video signal in the pixel electrode PX for a relatively
`long time even when the thin film transistor TFT is turned
`off after the video signal from the drain signal line DL is
`applied to the pixel electrodes PX through the thin film
`transistor TFT.
`0081. Here, the capacitance of the capacitive element
`Cstg is proportional to the overlapped area of the counter
`electrode CT and the respective pixel electrodes PX, and the
`overlapped area is relatively increased. The dielectric film of
`the capacitance has a Stacked layer Structure formed of the
`insulation film GI and the protective film PAS.
`0082 It is needless to say that the material of the pro
`tective film PAS is not limited to SiN and may be formed of
`Synthetic resin, for example. In this case, Since the protective
`film PAS can be formed by coating, it is possible to obtain
`an advantageous effect in that the manufacture of the liquid
`crystal display device can be facilitated even when the film
`thickness of the protective film PAS is increased.
`0.083. Further, on a surface of the transparent substrate
`SUB1 on which the pixel electrodes PX and the counter
`electrode CT are formed, an orientation film ORI1 is formed,
`such that the orientation film ORI1 also covers the pixel
`electrodes PX and the counter electrode CT. The orientation
`film ORI1 is a film which is directly brought into contact
`with the liquid crystal LC and is provided for determining
`the initial orientation direction of the liquid crystal LC.
`0084.
`In the above-mentioned embodiment, an explana
`tion has been given of an example using ITO as the material
`of the transparent conductive film. However, it is needless to
`say even when IZO (Indium-Zinc-Oxide) is u