WO2001033292A1

WO2001033292A1 - Liquid crystal display device

Info

Publication number: WO2001033292A1
Application number: PCT/JP1999/006018
Authority: WO
Inventors: Takeshi Sato; Genshiro Kawachi; Yoshiro Mikami; Katsumi Kondo
Original assignee: Hitachi, Ltd.
Priority date: 1999-10-29
Filing date: 1999-10-29
Publication date: 2001-05-10

Abstract

A high-angle-of-field, high-aperture-ratio, high-accuracy liquid crystal display device which comprises opposing substrates sandwiching a liquid crystal therebetween and a thin-film transistor substrate, which has a thin-film transistor to be turned on by a scanning signal line and provided on the thin-film transistor substrate, and which forms for application onto a liquid crystal an electric field in parallel with the thin-film transistor substrate and between a pixel electrode connected to a thin-film transistor's source and a counter electrode connected to a counter voltage signal line so as to control a transmission light, wherein at least one of the pixel electrode and the counter electrode is composed of a conductive film mainly containing Si, use of the Si-containing conductive film enabling a high-accuracy fine-fabrication of the pixel electrode and the counter electrode to provide a high-angle-of-field, high-accuracy, high-aperture-ratio, horizontal electric field type liquid crystal display device. A built-in circuit method with a reduced drive voltage will, if used, provide a higher-accuracy, higher-angle-of-field liquid crystal display device.

Description

Specification

Liquid crystal display technology

The present invention relates to a liquid crystal display device, and more particularly to a liquid crystal display device in which a pixel electrode and a counter electrode are arranged on the same substrate, and a liquid crystal is controlled and displayed by applying a voltage between both electrodes. It relates to electrode materials and electrode structures. Background art

In a conventional liquid crystal display device, the pixel electrode of the transparent conductive film formed on the transparent insulating substrate and the liquid crystal held between the counter electrodes of the transparent conductive film formed on the opposing substrate generally have 2. Description of the Related Art A vertical electric field type liquid crystal display device that controls display by changing the alignment direction of liquid crystal molecules by applying a vertical electric field is widely used.

Generally, such a vertical electric field type liquid crystal display device has a problem that a viewing angle is narrow. On the other hand, as disclosed in Japanese Patent Application Laid-Open No. 9-73101, an electric field substantially parallel to the substrate is generated between the pixel electrode and the counter electrode, which are alternately arranged, and form a so-called comb electrode. In recent years, a lateral electric field type liquid crystal display device that drives a liquid crystal has been used.

FIG. 26 shows an example of a pixel portion of a conventional in-plane switching mode liquid crystal display device.

Scanning signal lines 52 and 53, video signal line 13 and counter voltage signal line 54 are formed on transparent insulating substrate 2 made of glass, near the intersection of scanning signal line 52 and video signal line 54. A thin film transistor 8 using amorphous Si is formed. The thin film transistor 8 has a transparent conductive film I T0 It is connected to a pixel electrode 3 made of a film. The counter voltage signal line is connected to a counter electrode 4 made of a metal film of the same layer, and generates an electric field that is substantially parallel to the substrate between the counter electrode 4 and the pixel electrode to drive the liquid crystal.

Further, as disclosed in Japanese Patent No. 265399, a liquid crystal display device in which a driving circuit is formed on a thin film transistor substrate using a thin film transistor is known. In this liquid crystal display device, the number of parts can be reduced to reduce costs, and the number of connection points to external terminals can be reduced. Therefore, finer wiring intervals can be realized, and high definition can be achieved. Disclosure of the invention

In a conventional in-plane switching liquid crystal display device using a ITO film or metal film as a pixel electrode and a counter electrode, it is difficult to miniaturize the electrodes by using inexpensive jet etching to process the ITO film and the metal film. Met. In a horizontal electric field type liquid crystal display device, the pixel electrode and the counter electrode cannot be used as a light transmission region except for the vicinity of the end even if they are formed of a transparent conductive film. When the precision of the pixel electrode was increased, the pixel electrode and the counter electrode could not be miniaturized, so that the aperture ratio was remarkably reduced, which led to a reduction in luminance and an increase in backlight power consumption, which was not practical.

Also, it is difficult to miniaturize a lateral electric field type liquid crystal display device in which a pixel electrode and a counter electrode are formed using ITO as a material. Therefore, in order to secure an aperture ratio, it is necessary to increase the electrode interval between the pixel electrode and the counter electrode, and there is a problem that the driving voltage is high. If a driving circuit is built into a horizontal electric field type liquid crystal display device to obtain a higher definition and higher viewing angle liquid crystal display device, it is difficult to drive the liquid crystal with a low driving voltage obtained by the built-in driving circuit. there were. An object of the present invention is to provide a liquid crystal display device having a high viewing angle, a high aperture ratio, and a high definition.

to this end,

A first feature of the liquid crystal display device of the present invention is that at least one of the pair of substrates is transparent, a liquid crystal layer sandwiched between the pair of substrates, and at least one of the pair of substrates is arranged on at least one of the substrates. A video signal electrode, a scanning signal electrode arranged to cross the video signal electrode, a thin film transistor arranged near an intersection of the video signal electrode and the scanning signal electrode, a pixel electrode connected to the thin film transistor, and a pixel A counter electrode arranged in the same direction as the direction in which the electrodes are arranged, and performing display by controlling the liquid crystal molecules of the liquid crystal layer by a voltage applied between the pixel electrode and the counter electrode. The pixel electrode and the counter electrode are made of a conductive film containing Si as a main component.

A second feature of the liquid crystal display device of the present invention is that at least one of the pair of substrates is transparent, a liquid crystal layer sandwiched between the pair of substrates, and at least one of the pair of substrates is disposed on one of the substrates. A video signal electrode, a scanning signal electrode arranged to cross the video signal electrode, a thin film transistor arranged near the intersection of the video signal electrode and the scanning signal electrode, a pixel electrode connected to the thin film transistor, and a pixel A counter electrode disposed in the same direction as the electrodes, and displaying by controlling the liquid crystal molecules of the liquid crystal layer by a voltage applied between the pixel electrode and the counter electrode; Alternatively, the counter electrode is formed of a conductive film containing Si as a main component.

A third feature of the liquid crystal display device of the present invention is that at least one of the pair of substrates is transparent, a liquid crystal layer sandwiched between the pair of substrates, and at least one of the pair of substrates is disposed on one of the substrates. A video signal electrode; a scanning signal electrode arranged to cross the video signal electrode; and an intersection of the video signal electrode and the scanning signal electrode. A thin film transistor arranged near the point, a pixel electrode connected to the thin film transistor, and a counter electrode arranged in the same direction as the pixel electrode, and a liquid crystal is applied by a voltage applied between the pixel electrode and the counter electrode. The display is performed by controlling the liquid crystal molecules in the layer, and the pixel electrode or the counter electrode is formed of a conductive film containing Si as a main component.

A fourth feature of the liquid crystal display device of the present invention is that at least one of the pair of substrates is transparent, a liquid crystal layer sandwiched between the pair of substrates, and the at least one of the pair of substrates is disposed on at least one of the substrates. A video signal electrode, a scanning signal electrode arranged so as to intersect with the video signal electrode, a thin film transistor arranged near an intersection of the video signal electrode and the scanning signal electrode, a pixel electrode connected to the thin film transistor, and a pixel. A counter electrode arranged in the same direction as the electrodes, and displaying by controlling the liquid crystal molecules of the liquid crystal layer by a voltage applied between the pixel electrode and the counter electrode; It is composed of a crystalline semiconductor film and the counter electrode is composed of ITO.

A fifth feature of the liquid crystal display device of the present invention is that at least one of the pair of substrates is transparent, a liquid crystal layer sandwiched between the pair of substrates, and an image arranged on at least one of the pair of substrates. A signal electrode, a scanning signal electrode arranged to cross the video signal electrode, a thin film transistor arranged near an intersection of the video signal electrode and the scanning signal electrode, a pixel electrode connected to the thin film transistor, and a pixel electrode And a counter electrode disposed in the same direction as that of the pixel electrode. The display is performed by controlling the liquid crystal molecules of the liquid crystal layer by a voltage applied between the pixel electrode and the counter electrode. The counter electrode is composed of a polycrystalline semiconductor film.

A sixth characteristic of the liquid crystal display device of the present invention is that at least one of the pair of substrates is transparent, a liquid crystal layer sandwiched between the pair of substrates, and at least one of the pair of substrates. A video signal electrode disposed on one of the substrates, a scanning signal electrode disposed so as to cross the video signal electrode, a thin film transistor disposed near an intersection of the video signal electrode and the scanning signal electrode; A pixel electrode connected to the thin-film transistor; and a counter electrode disposed in a plane different from the layer on which the pixel electrode is disposed with an insulating film interposed therebetween, and applied between the pixel electrode and the counter electrode. In a liquid crystal display device that performs display by controlling the liquid crystal molecules of the liquid crystal layer by the applied voltage, the pixel electrodes are formed of a conductive film containing Si as a main component, and are arranged in a plane. The opposing electrode is constituted by a transparent electrode. A seventh feature of the liquid crystal display device of the present invention is that the opposing substrate and the thin film transistor substrate facing each other with the liquid crystal interposed therebetween, and the thin film transistor substrate Cross each other A video signal electrode and a scanning signal electrode, a thin film transistor disposed near an intersection of the scanning signal electrode and the video signal electrode, and a pixel electrode connected to a source of the thin film transistor. A substantially parallel electric field is formed on the thin film transistor substrate between the opposing electrodes connected to the opposing voltage signal lines arranged in the same direction as the pixel electrodes, and applied to the liquid crystal to control the transmitted light. At least one of the electrode and the counter electrode is made of a conductive film containing Si as a main component.

An eighth feature of the liquid crystal display device of the present invention is that an opposing substrate and a thin film transistor substrate which face each other with a liquid crystal interposed therebetween, a video signal line and a scanning signal line crossing each other on the thin film transistor substrate, a scanning signal line and a video signal line A thin film transistor connected to the video signal line and turned on by the scanning signal line, and a pixel electrode connected to the source of the thin film transistor. A substantially parallel electric field is formed on the thin-film transistor substrate between the counter electrodes connected to the signal lines and applied to the liquid crystal to control the transmitted light, and the thin-film transistor has a channel made of a polycrystalline Si film. And the pixel electrode or Means that the counter electrode is formed of the same conductive film as the channel in the same layer as the channel.

A ninth feature of the liquid crystal display device of the present invention is that the liquid crystal display device has at least one pair of transparent substrates and a liquid crystal layer sandwiched between the substrates, and one of the pair of substrates has at least a surface thereof. Semiconductor having a transparent electrode formed on an insulating main surface, and a patterned semiconductor layer opposed to the transparent electrode via the first insulating layer at least. That is, the liquid crystal layer is driven by an electric field generated between the layer and the transparent electrode.

A tenth feature of the liquid crystal display device of the present invention is that the liquid crystal display device has at least one transparent substrate and a liquid crystal layer sandwiched between the substrates, and one of the pair of substrates has at least one. In each case, the surface is insulative, the transparent electrode formed on the insulative main surface, the semiconductor layer formed on the first insulating layer, and a part of the semiconductor layer via the gate insulating layer. A plurality of thin film transistors each including an opposing gate electrode and a pair of semiconductor layers of the first conductivity type; a plurality of scan signal lines connected to the plurality of thin film transistors and formed so as to cross each other; and a plurality of video signals At least one of the pair of first conductive type semiconductor layers has a pattern and extends on the transparent electrode, and is generated between the patterned first conductive type semiconductor layer and the transparent electrode. Due to the electric field To drive the liquid crystal. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a diagram showing details of a pixel portion of a liquid crystal display device according to the present invention. FIG. 2 is a cross-sectional view of a pixel in FIG. 1 taken along a plane parallel to a scanning signal line. FIG. 3 is a cross section of the additional capacitor of FIG. Fig. 4 shows the thin film of Fig. 1. 3 is a cross section of a transistor. FIG. 5 is an equivalent circuit of a liquid crystal display device with a built-in drive circuit. FIG. 6 is an example of an equivalent circuit of a pixel. FIG. 7 is a diagram of an example in which a pixel electrode is connected to a storage capacitor 55 formed between the pixel electrode and the counter voltage signal line 44. FIG. 8 is an example of a liquid crystal display device using a thin-film transistor composed of a polycrystalline Si film having the pixels of FIG. FIG. 9 is an example of a method of manufacturing a thin film transistor substrate using a polycrystalline Si film having the pixels of FIG. FIG. 10 is an example of a pixel of the liquid crystal display device of the present invention. FIG. 11 is a cross section of the pixel of FIG. FIG. 12 is a cross section of the storage capacitor of the pixel of FIG. FIGS. 13 and 14 show a method of forming a thin film transistor substrate having the pixels shown in FIG. FIG. 15 is an example of a pixel of the liquid crystal display device according to the present invention. FIG. 16 is a cross-sectional view of the pixel in FIG. 15 from the drain contact layer 91 to the vicinity of the additional capacitance 90. Fig. 17

FIG. 15 is a cross-sectional view of the liquid crystal display device having the pixels of FIG. 15 in a direction perpendicular to the video signal line 13. FIG. 18 is an example of a pixel of the liquid crystal display device according to the present invention. FIG. 19 is an example of a pixel of the liquid crystal display device according to the present invention. FIG. 20 is a sectional view showing the vicinity of the thin film transistor of the pixel shown in FIG. FIG. 21 is a cross-sectional view near the storage capacitance of the pixel in FIG. Fig. 22 and Fig.

FIG. 23 shows an example of a method for manufacturing a thin film transistor substrate having the pixels shown in FIG. FIG. 24 is an example of a pixel of the liquid crystal display device according to the present invention. No.

FIG. 25 is a cross section corresponding to a section between A-A ′ in FIG. FIG. 26 shows an example of a pixel portion of an in-plane switching mode liquid crystal display device according to the prior art. BEST MODE FOR CARRYING OUT THE INVENTION

FIG. 1 is a diagram showing details of a pixel portion of a liquid crystal display device according to the present invention. A video signal line 13 and a scanning signal line 52 are arranged on a transparent insulating substrate 2, and a resource, a drain, and a channel are formed in a single layer by a polycrystalline Si film near the intersection. In addition, a coplanar thin-film transistor 8 having a gate electrode formed on the channel is formed. In FIG. 1, an n-type thin film transistor is formed. Further, as the transparent insulating substrate, for example, a glass substrate can be used.

The gate electrode 9 of the thin-film transistor 8 is formed of the same metal film as the scan signal line 52 on the same layer as the scan signal line 52, and is connected to the scan signal line 52. The drain 10 of the thin-film transistor 8 is connected to the video signal line 13 via the contact hole 7. Drain of thin-film transistor 8

Numeral 10 is a polycrystalline Si film in the same layer as the channel 22 of the thin-film transistor 8 and has the same n-type phosphorus as the source and drain of the thin-film transistor, and has conductivity. The pixel electrode 3 is formed. The pixel electrode 3 is connected to the source 11 of the thin-film transistor 8.

Further, the additional capacitance 1 is formed between the polycrystalline Si film in the same layer as the pixel electrode 3 and the preceding scanning signal line 53 via a gate insulating film. The pixel electrode 3 is connected to the lower capacitor electrode of the additional capacitor 1. At the top of video signal line 1 3

An ITO film, which is a transparent conductive film forming the counter voltage signal line 14 and the counter electrode 4, is deposited via an inorganic insulating film made of SiN and an organic insulator made of polyimide. The organic protective film 15 covers the video signal line 13 and the scanning signal lines 52 and 53, and is opened on the pixel electrode 3 to form the organic protective film opening 5. The counter electrode opening 6 is located inside the organic protective film opening 5. Ri Contact with the pixel electrode 3 and the counter electrode 4 is formed by the channel and the same layer film of either a thin film transistor in this embodiment, co ² required for connection to other conductive layers that are different stratified insulating film No contact hole is required, so that the light transmission area can be enlarged and the aperture ratio can be increased. This is particularly effective for securing the aperture ratio when the area of the contact hole cannot be ignored with the miniaturization of pixels.

FIG. 2 is a cross-sectional view of a pixel in FIG. 1 taken along a plane parallel to a scanning signal line. Video signal lines 13 made of a metal film are formed on a transparent insulating substrate 2 with a base film 19 and an interlayer insulating film 18 interposed therebetween. An inorganic protection film 16 made of SiN and an organic protection film 15 made of polyimide are formed on the video signal line 13. The organic protective film 15 is covered with an ITO film forming the counter electrode 4. Further, a pixel electrode 3 made of a polycrystalline Si film is formed on the transparent insulating substrate 2 via a base film 19, and the pixel electrode 3 is covered with only the inorganic protective film 16. The direction of liquid crystal molecules is controlled by applying a voltage to the pixel electrode 3 and the counter electrode 4.

If the pixel electrode 3 is made of a Si film as in the present embodiment, the chemical resistance is superior to a case where the pixel electrode is formed of a metal film that can be dry-etched, for example, an A1 alloy. . That is, if the pixel electrode 3 is made of a Si film, even if the inorganic protective film 16 on the pixel electrode 3 is made thinner, it is possible to suppress damage to the electrode due to the etching solution when etching the ITO film of the counter electrode. Things.

In addition, by forming the pixel electrode 3 with a Si film, it is possible to reduce defects due to the reaction with the liquid crystal.

Further, since no pattern having a step is formed below the pixel electrode 3, there is no disconnection occurring at the step, and the yield is improved. Further, by reducing the thickness of the inorganic protective film 16, the electric flux passing through the insulating film can be reduced, the electric field applied to the liquid crystal can be increased, and the driving voltage can be reduced.

In addition, according to the present embodiment, the IT layer formed on the side wall of the inorganic protective film 16 can be used. The opposing electrode 4 made of a film has an effect of shielding the electric field from the video signal line 13 to reduce crosstalk of a signal between pixels and improving image quality.

FIG. 3 is a cross-section of the additional capacitor of FIG.

A pixel electrode 3 composed of a polycrystalline Si film which is mounted on a transparent insulating substrate 2 via a base film 19, and a polycrystalline Si film which is doped with a phosphorus and boron. Pn connection region 31, boron-doped capacitive contact layer

3 2, Capacitive lower electrode 33 made of non-doped Si film

They are formed from Si films and are connected to each other. The capacitive contact layer 32 connected to the capacitive lower electrode 33 is self-aligned to p-type, which is different from the source and drain of the thin film transistor, by boron doping using the scanning signal line as a mask. Is formed. Also, connect between the capacitive contact layer 32 and the pixel electrode 3 doped with the same n-type as the source and drain.

The Pn connection region 31 is made of a polycrystalline Si film doped with phosphorus and boron.

The capacitance contact layer 32 is poled at a concentration of 10 20 cc or more, and the pixel electrode 3 is closed at a concentration of 10 20 cc or more. You. The P n connection region 32 1 is heavily doped with both phosphorus and boron. The contact between the capacitance contact 32 and the pixel electrode 3 is ensured. Capacitor lower electrode 3 3 gate insulating film 1-7 to previous scan signal line 5 3 via consisting of S i 0 ₂ film on are formed, added between the scanning signal line 3 and the capacitor lower electrode 3 3 volume 1 Is formed. The additional capacitor 1 holds a negative voltage at which the preceding scanning signal line 53 turns off the n-type thin-film transistor, thereby inducing a hole in the polycrystalline Si film forming the lower electrode 33 of the capacitor. Then, it is electrically connected to the connected capacitor contact layer 32 made of the P-type polycrystalline Si film. The additional capacitance consists of the capacitance contact layer 32 and the pn connection area 31. It is electrically connected to the pixel electrode through the capacitor and functions as a capacitor for holding the potential of the pixel electrode. The additional capacitance 1 is formed via a gate oxide film which is thinner than a case where the capacitance is formed by the same conductive layer as the video signal wiring 13 via the interlayer insulating film 18 and a unit area. The capacity per unit can be increased, and the area of the additional capacity can be reduced to improve the aperture ratio. On the additional capacitor 1, an interlayer insulating film 18 made of SiO _2, an inorganic protective film 16 made of SiN, and an organic protective film 15 made of polyimide interposed through an ITO film The voltage signal lines 14 are stacked. The counter voltage signal line 14 also has the effect of blocking the electric field from the scanning signal line 53.

FIG. 4 is a cross section of the thin film transistor of FIG.

This figure shows a double-gate thin film transistor in which the gate electrode 9 is divided into two. A drain 11 and a source 10 and a source 10 and a polycrystalline Si film, which are connected to the transparent insulating substrate 2 via a base film 19 and are connected to a power of more than 10.sup.20 cc. LDD 21 (Lightly—Doped—Drain) consisting of a polycrystalline Si film that is low-concentrated in Zee and a non-doped polycrystalline S A channel 22 made of an i film is formed. A gate electrode 9 made of a metal film is formed on the channel 22 via a gate insulating film 17. The boundary between channel 22 and LDD 21 is formed in self-alignment with the end of gate electrode 9. This is a so-called LDD thin-film transistor in which the breakdown voltage is improved by the LDD 21 formed at the end of the channel 22 and the off-state current is reduced. The double-gate type, in which two thin-film transistors are formed in series, has a higher breakdown voltage and lower off-current than a single-gate thin-film transistor. The drain 11 is connected to a video signal line 13 made of a metal film via a contact hole 7 opened in the interlayer insulating film 18 and the gate insulating film 17. Source The pixel electrode 3 is connected to the pixel electrode 3 composed of the same layer of a phosphorus-doped polycrystalline Si film.

In Figs. 1 to 4, the source, drain, LDD and pixel electrode of the thin film transistor are n-type polycrystalline Si, and the capacitor contact layer is a p-type polycrystalline Si film. However, the source, drain, LDD, and pixel electrode of the thin-film transistor can be P-type polycrystalline Si films, and the capacitor contact layer can be formed of n-type polycrystalline Si.

Next, the operation of the liquid crystal display device using the pixel shown in FIG. 1 will be described.

FIG. 5 is an equivalent circuit of a liquid crystal display device with a built-in drive circuit.

The scanning signal lines 42 and the video signal lines 13 that intersect each other are arranged in a matrix on the substrate 40. A scanning signal line driving circuit 42 connected to a scanning signal line and a video signal line driving circuit 41 connected to a video signal line 13 are formed of a polycrystalline Si film on the periphery of the substrate 40. It is composed of a so-called CMOS circuit using n-type and p-type thin film transistors. A counter voltage signal line 44 is arranged in parallel with the scanning signal line 42. Pixels 45 are formed in a region defined by the scanning signal line 42 and the video signal line 13. The substrate 40 is a transparent insulating substrate, for example, a glass substrate can be considered. FIG. 6 is an example of an equivalent circuit of a pixel.

A thin film transistor 8 is formed near the intersection of the video signal line 13 and the scanning signal line 52. The drain 11 of the thin-film transistor 8 is connected to the video signal line 13, and the source 10 of the thin-film transistor 8 is extended to the pixel electrode 3. The gate electrode 9 of the thin-film transistor 8 is connected to the scanning signal line 52. The counter electrode 4 is connected to a counter voltage signal line 44. The pixel electrode 3 forms an additional capacitor 51 with the preceding scanning signal line 53. The pixel electrode 3 and the counter electrode 4 are formed in parallel on the same substrate, and are substantially flat on the substrate. It has the function of generating a strong electric field and applying the electric field to the liquid crystal. To drive the liquid crystal, a positive voltage is applied to the selected scanning signal line 52 to turn on the thin-film transistor 8 connected to the scanning signal line. The signal voltage from the video signal line 13 is applied to the pixel electrode 3 via the thin film transistor 10, and the additional capacitance 51 formed between the scanning signal line 53 at the previous stage and the counter electrode 4 via the liquid crystal. The liquid crystal capacitor 50 formed during the writing is charged and writing is performed. When a negative voltage is applied to the selected scanning signal line 52 to turn off the thin film transistor, the video signal line 13 is electrically separated from the pixel electrode 3, and the pixel electrode 3 is connected to the additional capacitance 51 and The signal voltage is held by the electric charge charged in the liquid crystal capacitor 50. In FIG. 5, writing is performed by sequentially selecting the scanning signal lines 42, a predetermined signal voltage is applied to each pixel to drive the liquid crystal, and an image is displayed. Note that instead of connecting the pixel electrode to the additional capacitance 51 formed between the scanning electrode and the preceding scanning electrode in FIG. 6, the pixel electrode was formed between the pixel electrode and the counter voltage signal line 44 as shown in FIG. It can also be connected to the storage capacity 55. The storage capacitor 55 has an effect of holding the signal voltage applied to the pixel electrode 3, similarly to the additional capacitor 51.

FIG. 8 is an example of a liquid crystal display device using a thin-film transistor composed of a polycrystalline Si film having the pixels of FIG.

The liquid crystal 62 is a liquid crystal having a positive dielectric anisotropy, and is sealed between the substrate 40 and the opposing substrate 61. The distance between the substrate 40 and the opposing substrate 61 is maintained by the maximum film thickness of the opposing voltage signal line 15 formed on the thin film transistor substrate. Both the substrate 40 and the opposing substrate 61 are formed of a transparent glass substrate, and an alignment film 64 for aligning the liquid crystal is formed on a surface in contact with the liquid crystal. In the alignment film 64, liquid crystal molecules are generally generated between the pixel electrode 3 and the counter electrode 4 by rubbing or anisotropic polymerization by polarized ultraviolet light. It has the function of orienting in the direction perpendicular to the electric field.

A color filter is formed on the counter substrate 61. A substantially parallel electric field is generated between the pixel electrode 3 and the counter electrode 4 formed on the substrate 40 to change the direction of the liquid crystal molecules and control the plane of polarization of the transmitted polarized light. (Not shown) to control the brightness of the pixel by converting it to the amount of transmitted light. Color display is performed by controlling the transmissivity of the pixels provided with color filters corresponding to the red, blue, and green colors. The transparent conductive film formed on the opposing substrate shields an electric field such as static electricity from the opposing substrate side and suppresses fluctuation of a liquid crystal display.

FIG. 9 is an example of a method of manufacturing a thin-film transistor substrate using a polycrystalline Si film having the pixels of FIG.

5 0 nm to S i N film on a transparent glass substrate 2 0, and the base film 1 9 is deposited by S i 0 ₂ film 1 0 0 nm respectively plasma CVD method. A non-doped amorphous Si (a-Si) film 71 is deposited to a thickness of 50 nm by low-pressure CVD using disilane. As shown in Fig. 9 (a), XeC1 pulse excimer laser light 70 is irradiated in a range of 30 OmJ to 50 OmJ per square centimeter, and the substrate is scanned to crystallize. The crystal Si film 72 is used. A SiO ₂ film serving as a gate insulating film 22 is deposited to a thickness of 100 nm by a plasma CVD method using TE0S. A metal film made of Nb is deposited, and photolithography is performed by dry etching using CF ₄ gas to form a gate electrode 9 and a scanning signal line (not shown). Using the gate electrode 9 as a mask, doping is performed using a phosphorus ion implantation method so that the phosphorus concentration in the polycrystalline Si film is from 10 17 Z cc to 10 18 Z cc. An LDD 21 is formed to form a channel 22 made of non-doped polycrystalline Si in a self-aligned manner on the gate electrode 9 to obtain the structure shown in FIG. 9 (b). LDD when the phosphorus concentration is 10 17 cc or less 21 The resistance of 1 is large, and the on-current of the transistor decreases. Above 10 18 Zee, the electric field relaxation effect in the LDD decreases and the off-current increases. Next, as shown in FIG. 9 (c), the resist 73 is used as a mask, and the pixel electrode 3 is ion-implanted with phosphorus ions into the regions to be the source 10 and the drain 11 by ion implantation. Doping so as to be about 10 to the power of 20 / cc. Similarly, the pn connection region and the n-type transistor (not shown) of the driving circuit are similarly linked. In addition to the ion implantation, the gate insulating film can be removed by using a resist as a mask to expose the polycrystalline Si film, and can be doped by an ion shower method using PH ₃ gas. After the resist is removed, the resist is used as a mask in the capacitive contact layer, the Pn junction region, and the p-type transistor region (not shown) of the drive circuit, and the boron concentration in the Si film is also reduced. Doping is performed so that it becomes 10 20 or more cc or more. After removing the resist, the implanted phosphorus and boron are activated by excimer laser or thermal annealing.

Then TE 0 interlayer insulating film 1 8 S consisting by Ri S i 0 ₂ film to a plasma CVD using to 5 0 0 nm deposition. The interlayer insulating film 18 and the gate insulating film 17 on the drain 11 and the pixel electrode 3 are removed by photolithography by dry etching using CHF ₃ gas. A metal film made of a refractory metal such as Cr, M0, W, or an alloy of these is deposited to a thickness of 500 nm by sputtering, and a video signal is formed by photolithography using an エ -etch. A line 13 is formed and connected to the drain 11 of the thin film transistor to obtain the structure shown in FIG. 9 (d). A 500-nm-thick inorganic protective film 16 made of SiN is deposited by plasma CVD and applied to the liquid crystal display device by dry etching using CF ₄ or SF ₆ gas. After opening a terminal section (not shown) for supplying signals and power from the outside, an organic protective film 15 made of polyimide is applied and photo-coated. It is formed by selective polymerization using UV irradiation with a mask. The organic protective film 15 is a transparent conductive film made of IT 0 (Indium-Tin-Oxides) formed so as to open on the pixel electrode 3 and the terminal (not shown). A thin film transistor substrate having a cross-sectional structure of a pixel having the structure shown in FIG. 9-5 is formed by opening the pixel electrode 3 by photolithography using a wet etch. To form

In addition, in FIG. 9 (b), high-concentration ion implantation can be performed to form a single-drain thin-film transistor in which the source and the drain are directly connected to the channel without going through the LDD. It is known that p-type single-drain thin-film transistors are less deteriorated than n-type single-drain thin-film transistors. Are suitable.

FIG. 10 is an example of a pixel of the liquid crystal display device of the present invention.

The thin-film transistor 8 is formed near the intersection of the video signal line 13 and the scanning signal line 52. A pixel electrode 3 made of a polycrystalline Si film that is connected to the same layer as the channel connected to the source of the thin-film transistor 8, and a channel electrode that is also connected to the same layer as the channel. The opposing electrode 4 made of the polycrystalline Si film is formed. The counter voltage signal line 14 and the counter electrode 4 are connected via the contact holes 7 and 81 by the capacitor upper electrode 82 made of the same metal layer as the video signal line 13. I have. Further, a storage capacitor 55 is formed between the pixel electrode 3 and the capacitor upper electrode 82 via an interlayer insulating film and a gate insulating film.

FIG. 11 is a cross section of the pixel of FIG.

On a glass substrate 20, a pixel electrode 3 made of a polycrystalline Si film and a counter electrode 4 are arranged in the same layer close to each other with a base film interposed therebetween. On pixel electrode 3 By removing the interlayer insulating film 18 and the gate insulating film 17 in some parts, and reducing the distance between the liquid crystal and the electrode, the electric flux passing through the insulating film on the electrode is reduced and the efficiency of applying the electric field to the liquid crystal Is increasing. The protective insulating film 8 5 may be a transparent organic insulating film such as S i N, addition of an inorganic insulating film such as S i 0 _2, poly Lee Mi de.

FIG. 12 is a cross section of the storage capacitor of the pixel of FIG.

A pixel electrode 3 and a counter electrode 4 made of a polycrystalline Si film doped with phosphorus via a base film 19 are formed on a glass substrate 20. The counter electrode 4 is connected to a counter voltage signal line 14 made of the same conductive film as a scan signal line (not shown) via a capacitor upper electrode 82. The capacitor upper electrode 82 is formed of the same conductive film as the video signal line (not shown), and forms the storage capacitor 55 with the pixel electrode 3 via the interlayer insulating film 18 and the gate insulating film 17. .

13 and 14 show a method of forming a thin film transistor substrate having the pixels shown in FIG.

A polycrystalline Si film is formed on a glass substrate by the same method as in FIG. 9, and a polycrystalline Si film 72 is formed by photolithography in the shape shown in FIG. 13 (a). . Since the pixel electrode 3 and the counter electrode 4 are formed of the same layer of polycrystalline Si film, they can be processed with the same photomask, and there is no misalignment of the mask, and the uniformity of the distance between the pixel electrode 3 and the counter electrode 4 can be improved. In addition, the Si film can be added by dry etching, and the recession during etching from the resist tin can be reduced as compared with the ITO film processed by etching and the metal film for forming wiring. Next, a gate insulating film made of a SiO ₂ film is deposited. A conductive film made of Cr is deposited by sputtering, and photolithography is performed by a wet etch using an aqueous cerium nitrate solution to perform scanning signal lines 52 and 53 and a gate electrode 9 connected to scanning signal line 52. , And the counter voltage signal line 14 are formed. S i 0 ₂ film After depositing an interlayer insulating film made of, a contact hole 7 and an insulating film opening 84 are opened by photolithography using dry etching to obtain the structure shown in FIG. 14 (b). A conductive film in which a Cr film and an A1 alloy film are laminated to a thickness of 60 nm and 400 nm, respectively, is deposited by sputtering, and the A1 alloy film and the Cr film are each subjected to photolithography by jet etching. The video signal line 13 and the upper portion 82 of the capacitor electrode are formed by using this to obtain the structure shown in FIG. 14 (b). A protective insulating film made of SiN is deposited to a thickness of 800 nm, and a terminal portion (not shown) is opened by photolithography to obtain a thin film transistor substrate having the pixels shown in FIG.

The pixel structure of this embodiment has the effect of improving the uniformity of the distance between the pixel electrode and the counter electrode in a horizontal electric field type liquid crystal display device, suppressing the fluctuation of the electric field intensity applied to the liquid crystal, and improving the uniformity of the image quality. There is. Also, the withstand voltage of a thin-film transistor decreases as the gate length of the transistor is reduced. In the pixel of the present invention, the distance between the wirings can be reduced, and the liquid crystal can be driven even by a thin-film transistor in which the driving voltage of the liquid crystal is reduced to be miniaturized. A liquid crystal display device having a reduced non-display area by reducing the area of the built-in drive circuit by miniaturizing the transistor can be obtained.

FIG. 15 is an example of a pixel of the liquid crystal display device according to the present invention.

A light-shielding film 92 made of an opaque conductive film of the same layer as the video signal lines 13 is formed on a glass substrate, and a thin-film transistor 8 using a polycrystalline Si film is formed on the light-shielding film 92. I have. Insulating film made of S i 0 ₂ on _t the video signal line 1 3 Source 1 0 of the thin film transistor is connected to the video signal line 1 3 with a conductive film made of shea Li site de in the same layer as the counter electrode 4 The counter electrode 14 is formed via the underlying film, the gate insulating film, and the interlayer insulating film. In addition, the pixel electrode 3 is formed of a silicide film in the same layer as the counter electrode, and is connected to the drain 11 of the thin-film transistor via the contact hole 7. FIG. 16 is a cross-sectional view of the pixel of FIG. 15 from the drain contact layer 91 to the vicinity of the additional capacitance 90.

On a glass substrate 20, a video signal line 13 and a light-shielding film 92 made of a Cr film having a thickness of 200 nm are formed. The light-shielding film 92 shields light from the backlight of the liquid crystal display device that enters the channel 22 and the LDD 21 from the substrate 20 side, thereby suppressing the leak current of the thin-film transistor and stabilizing the voltage of the pixel electrode. Has the effect of improving the image quality. The ends of the light shielding film 92 and the video signal line 13 are formed in a forward tapered shape having a gentle angle. When the end of the video signal line 13 has a forward tapered shape, a decrease in crystallinity due to a step at the time of crystallization due to excimer laser annealing of the Si film formed on the end can be suppressed. In order to form the conductive film made of Cr into a forward tapered shape at the end, for example, it can be formed by photolithography using a wet etch using an etchant containing nitric acid. The video signal line 13 is connected to the drain of the thin-film transistor 8 via a drain contact layer 91 composed of a silicide. The source of the thin-film transistor 8 is connected to the pixel electrode 3. The gate electrode 9 of the thin-film transistor 8 is connected to the scanning signal line 52, and a switch for electrically connecting and separating between the video signal line 13 and the pixel electrode 3 by the voltage of the scanning signal line 52. Perform the function of The pixel electrode forms an additional capacitor 90 between the pixel electrode and the preceding scanning signal line 53 via an interlayer insulating film. The additional capacitance 90 has a function of holding the voltage of the pixel electrode 3.

The drain contact layer 91 and the pixel electrode 3 are formed of a conductive silicide film. The silicide film can be deposited by, for example, a sputtering method using a silicide target. Also, like the Si film, it can be processed with high precision by photolithography using dry etching. Since the silicide film has a lower resistance than the Si film, it can be used for the counter voltage signal line. Silicide film For example, silicides of high melting point metals such as W, Mo, and Ta can be used. In addition, compared to the case where these refractory metal films are used as electrode films, they have better chemical resistance and can reduce the occurrence of defects due to the reaction between the liquid crystal and the electrodes.

FIG. 17 is a cross-sectional view of the liquid crystal display device having the pixels of FIG. 15 in a direction perpendicular to the video signal line 13.

Liquid crystal having a positive dielectric anisotropy is sealed between the glass substrate 20 and the opposing substrate 61, and the distance between the glass substrate 20 and the opposing substrate 61 is determined by plastic beads 95 of a predetermined size. Is held. On the glass substrate 2 0 is formed by the video signal Line 1 3, the base film 1 9 consisting of S i 0 ₂ on the video signal line 1 3 is al, an gate insulating film 1-7 and the interlayer insulating film 1 8 An opposing electrode 4 is formed via this. The pixel electrode 3 is formed of a conductive layer on the same layer as the counter electrode. A voltage is applied between the pixel electrode 3 and the counter electrode 4 to apply a substantially parallel electric field to the substrate. The counter electrode 4 also has the effect of shielding the electric field from the video signal line 13 and reducing crosstalk to improve image quality. An alignment film 64 for aligning liquid crystal is formed on the glass substrate 20 and the counter substrate 61, and is subjected to a rubbing treatment so as to align liquid crystal molecules in a direction substantially parallel to the video signal line 13. Due to the electric field applied between the pixel electrode 3 and the counter electrode 4, the liquid crystal molecules rotate in the direction of the lines of electric force 96, rotate the plane of polarization of the transmitted light, and rotate a polarizing plate (not shown). The amount of transmitted light is controlled. In this embodiment, since the pixel electrode is in contact with the liquid crystal only through the thin alignment film, an electric field can be effectively applied to the liquid crystal, and the driving voltage can be reduced.

FIG. 18 is an example of a pixel of the liquid crystal display device according to the present invention.

The cross-sectional structure is the same as that of the pixel of FIG. 1, and the pixel electrode 3 and the counter electrode 4 have a bend in the pixel. Electric fields are applied to the liquid crystal 62 in different directions within the pixel due to the bending of the electrode between the pixel electrode 3 and the counter electrode 4. You. The liquid crystal 62 is oriented along the electric field, and the viewing angle characteristics are improved by having different orientations in the pixel.

FIG. 19 is an example of a pixel of the liquid crystal display device according to the present invention.

An in-plane switching type liquid crystal display device having a thin film transistor composed of an a-Si film on a glass substrate 20 is shown. A pixel electrode 3 and a counter electrode 4 are formed of a laminated film of n + a-Si and non-doped a-Si having conductivity and being doped with phosphorus. On the video signal line 13 made of a metal film, an a-Si line 100 composed of n + a-Si and a non-a-Si is formed at the lower part to enhance the resistance to disconnection. . In the vicinity of the intersection of the video signal line 13 and the scanning signal line 52, the source 10 using the a_S i film, the drain 11 and the channel 11 are placed on the gate electrode 9 via the gate insulating film. It has an inverted staggered thin film transistor formed by the above method. The drain 11 is connected to the pixel electrode 3 via a drain wiring 102 made of the same metal film as the video signal line. In addition, the counter voltage signal line 14 made of the same metal film as the scan signal line 52 and the counter voltage wire 103 made of the same metal film as the video signal line are connected via the through-hole 101 to the top. They are connected to each other by the ITO film 93 formed in the above. The counter electrode 4 is connected to the counter voltage signal line 14 through the counter voltage wiring 103 and the ITO film 93. An organic protective film opening 4 in which an organic protective film is opened is formed above the pixel electrode 3 and the counter electrode 4.

FIG. 20 is a cross-sectional view of the vicinity of the thin-film transistor 8 of the pixel shown in FIG.

A gate electrode 9 is formed on a glass substrate 20, and a thin-film transistor 8 having a source 10, a drain 11, and a channel 22 formed via a gate insulating film 17 is formed. . The source 10 of the thin-film transistor 8 is connected to the video signal line 13 made of a metal film, and the drain 11 is connected to the drain wiring. Through 102, it is connected to the pixel electrode 3 composed of a laminated film of n + a-Si104 and the node a-Si105. An organic protective film 15 is opened on the pixel electrode 3 and is protected by an inorganic protective film 16.

FIG. 21 is a cross-sectional view near the storage capacitor of the pixel in FIG.

A counter voltage signal line 14 made of a metal film is formed on the glass substrate 20 in the same layer as the scanning signal line 12. Gate insulating film on opposing voltage signal line 14

A drain wiring 102 connected to the pixel electrode 3 of the previous stage pixel via 17 is formed, and a storage capacitor 55 for holding the signal voltage of the previous stage pixel electrode is formed. The opposing voltage signal line 14, the ITO film 93, and the opposing voltage wiring are provided via the through hole 101 having the gate insulating film 17 and the inorganic protective film 16 opened.

103 is connected. The counter voltage wiring 103 is connected to the counter electrode 4 composed of a laminated film of n + a—Si 104 and non-doped a—Si 105, and the upper part of the counter electrode 4 is an inorganic protective film 16 And the organic protective film 15 is opened.

FIGS. 22 and 23 show an example of a method of manufacturing a thin film transistor substrate having the pixels shown in FIG. Fig. 22 and Fig. 23 are

The manufacturing process at the cross section of FIG. 20 and FIG. 21 is shown.

A metal film made of Cr is deposited on a glass substrate 20 by sputtering to a thickness of 200 nm, and is gated to a scanning signal line and a counter voltage signal line 14 by photolithography using an ゥ et etch. A contact electrode 9 is formed. Gate insulating film made of SiN

After depositing by the 300-nm plasma CVD method, the a-Si of the node and n + a-Si, which is the phosphorus-doped a-Si, are each deposited by plasma CVD at 200 nm. Deposit 0 nm and 50 nm. The non-doped a-Si 105 and n + a Si 104 are processed by photolithography using dry etching to obtain the shapes shown in FIGS. 22 (a) and 23 (a). A metal film made of Cr Deposited 200 nm by sputtering, and processed by photolithography in the same way to form video signal line 13, drain wiring 102, and counter voltage wiring 103.

(b) and Fig. 23 (b). A resist is applied and exposed and developed using a photomask to form a resist pattern in which the area of the thin film transistor 8 is opened in FIG. 22 (c), and the resource 10 and the drain are dry-etched. 11 Using the metal film on 1 as a mask, n + a-Si and a part of the non-doped a-Si in the channel portion are removed by dry etching, and a channel 22 is formed to form a thin film transistor. Form 8. Next, an inorganic protective film 16 made of SiN is deposited again by a 200-nm plasma CVD method. Photolithography by dry etching using SF ₆ gas is performed, and through holes 101 are opened in the inorganic insulating film 16 and the gate insulating film 17 to obtain the structure shown in FIG. 23 (c). . Next, an ITO film is deposited to a thickness of 140 nm by sputtering, and is processed into a shape of the IT0 film 93 by photolithography using a wet etch. An organic protective film made of polyimide was applied and processed by exposure and development using a photomask or RIE using oxygen, as shown in Figs. 22 (d) and 23 (d). A thin film transistor substrate having a structure is obtained. The organic protective film has an effect of suppressing the reaction between the liquid crystal and the metal film forming the wiring.

The metal film that forms the video signal line and the scanning signal line is Cr,

High-melting-point metals such as Mo and W, which have excellent contact properties with Si, and alloys thereof can also be used. The Mo alloy has excellent contact properties with the ITO film.

In the present embodiment, the pixel electrode and the counter electrode are formed using a conductive n + a-Si film having higher chemical resistance than the metal film forming the video signal line, and the liquid crystal is formed only by the inorganic protective film. Since it has sufficient chemical resistance, the organic protective film on the pixel electrode and the counter electrode can be opened, and the electric field applied to the liquid crystal increases. This has the effect of reducing the drive voltage. Also, since processing by dry etching is possible, the pixel electrode can be made thinner to increase the aperture ratio.

FIG. 24 is an example of a pixel of the liquid crystal display device according to the present invention.

An opposing electrode 4 made of an ITO film is formed on the entire surface of the transparent insulating substrate 2. A transparent insulating film made of a silicon oxide film is formed on the counter electrode 4. A coplanar thin-film transistor 8 in which a resource, a drain, and a channel are formed in the same layer by a scanning signal line 52 and a polycrystalline Si film on a transparent insulating film, and a gate electrode is formed on the channel. Is formed. Further, a video signal line 13 is formed via an interlayer insulating film 18. The gate electrode of the thin-film transistor 8 is formed of the same metal film as the scanning signal line 52 and is connected to the scanning signal line 52. The drain 10 of the thin-film transistor 8 is connected to the video signal line 13 via the contact hole 7. The conductive pixel electrode 3 is made of a polycrystalline Si film in the same layer as the channel 22 of the thin-film transistor, is doped with the same n-type phosphorus as the source and drain of the thin-film transistor, and has conductivity. Is formed. The pixel electrode 3 is connected to the source 11 of the thin-film transistor. In Fig. 24, phosphorus is used for doping the source and drain and the pixel electrode to form an N-type thin film transistor and a pixel electrode, but boron is used instead of phosphorus and a P-type Thin film transistor. An inorganic protective film 16 made of a silicon nitride film is formed on the scanning signal line, the video signal line, and the thin film transistor. On the pixel electrode 3, an interlayer insulating film 18 and an inorganic protective film 16 are opened. Thus, an inorganic protective film opening 111 is formed.

FIG. 25 is a cross section of the liquid crystal display device of the present invention corresponding to a section taken along line AA ′ of FIG. 24.

A counter electrode 4 made of IT 0 is placed on a transparent insulating substrate 2 made of a glass substrate. Is formed. On the counter electrode 4, a transparent insulating film 110 having a thickness of 500 nm made of a silicon oxide film is formed.

On the transparent insulating film 110, a pixel electrode 3 made of a polycrystalline Si film is formed. The pixel electrode 3 is formed of the same layer as the channel of the thin-film transistor 8 and is continuously connected to the source 11 of the thin-film transistor.

The transparent insulating film may be a silicon oxide film, a silicon nitride film, or a laminated film of a silicon oxide film and a silicon nitride film. Silicon nitride films are suitable for preventing diffusion of impurities from glass and ITO.

In the pixel of this structure, the liquid crystal is driven in a region where the electric field is substantially parallel to the substrate at the end of the pixel electrode by the electric lines of force 96 generated between the pixel electrode 3 and the counter electrode 4. On the pixel electrode 3, an alignment film 64 for aligning the liquid crystal is formed. In the pixel having this structure, the pixel electrode is formed on the transparent insulating film 110 having no step, and is continuously connected to the drain, so that there is no disconnection at the step, so that the yield can be improved. . In addition, there is no misalignment between the pixel electrode and the counter electrode, and there is no display non-uniformity due to a change in the electrode interval. Further, since a sufficiently large storage capacitor is formed between the pixel electrode 3 and the counter electrode 4, it is not necessary to provide an additional area for the storage capacitor, and the aperture ratio can be increased. Further, in this embodiment, the structure is such that only the alignment film is interposed between the pixel electrode 3 and the liquid crystal, so that an effective electric field can be applied to the liquid crystal and the liquid crystal can be driven with a low driving voltage.

In the pixel of this embodiment, in addition, a polycrystalline Si film, which is easy to perform fine processing, is used for the pixel electrode, and there is an advantage that the pixel electrode 3 can be made thinner to improve the aperture ratio. As a result, the electric field at the end of the electrode becomes stronger, so that the liquid crystal can be driven at a lower voltage, thus forming the liquid crystal on the thin film transistor substrate. The liquid crystal can also be driven by a built-in low-breakdown-voltage drive circuit consisting of a polycrystalline Si thin-film transistor. For this reason, the liquid crystal display device having the pixel of the present invention has an advantage that a driving circuit is built in and high definition can be achieved.

In this embodiment, the polycrystalline Si is used for the pixel electrode. However, in addition to the polycrystalline Si film, the conductive amorphous silicon film and the silicide film are different from the channels of the thin film transistor. Since it is a horizontal electric field method that can be formed and used as a layer, the pixel electrode does not need to be transparent, and even if transparency is sacrificed, the thickness of the film is adjusted according to the sheet resistance required for the pixel electrode. Amorphous Si films that can be increased and have higher resistance than polycrystalline Si can also be used with increased film thickness. Also, an opaque silicide film can be used as an electrode. In either case, fine processing can be performed by dry etching using a fluorine-based gas, and a high-definition, high-definition horizontal electric field type liquid crystal display device can be formed.

According to the present invention, by forming a pixel electrode or a counter electrode with a conductive film containing Si as a main component, it is possible to improve the aperture ratio and reduce the driving voltage of a horizontal electric field type liquid crystal driving device. . Also, the yield can be improved. Industrial applicability

As described above, in the liquid crystal display device according to the present invention, since the pixel electrode or the counter electrode is formed of the conductive film containing Si as a main component, the aperture ratio can be particularly improved and the driving voltage can be reduced. Thus, a liquid crystal display device with low power consumption can be configured.

Claims

The scope of the claims

1. At least one of a pair of transparent substrates, a liquid crystal layer sandwiched between the pair of substrates, a video signal electrode disposed on at least one of the pair of substrates, Scanning signal electrodes arranged so as to intersect, a thin film transistor arranged near the intersection of the video signal electrode and the scanning signal electrode, a pixel electrode connected to the thin film transistor, and a direction in which the pixel electrode is arranged A liquid crystal display device having a counter electrode disposed in the same direction as that of the liquid crystal layer, and performing display by controlling liquid crystal molecules of the liquid crystal layer with a voltage applied between the pixel electrode and the counter electrode. At

The liquid crystal display device, wherein the pixel electrode and the counter electrode are formed of a conductive film containing Si as a main component.

2. The liquid crystal display device according to claim 1, wherein the pixel electrode and the counter electrode are formed in the same layer.

3. At least one of a pair of transparent substrates, a liquid crystal layer sandwiched between the pair of substrates, a video signal electrode disposed on at least one of the pair of substrates, Scanning signal electrodes arranged so as to intersect, thin film transistors arranged near intersections of the video signal electrodes and the scanning signal electrodes, pixel electrodes connected to the thin film transistors, and arranged in the same direction as the pixel electrodes A liquid crystal display device, comprising: a counter electrode formed in the liquid crystal layer, wherein a display is performed by controlling liquid crystal molecules of the liquid crystal layer by a voltage applied between the pixel electrode and the counter electrode.

The liquid crystal display device, wherein the pixel electrode or the counter electrode is formed of a conductive film containing Si as a main component.

4. The liquid crystal display device according to claim 3, wherein the pixel electrode and the counter electrode are formed in the same layer.

5. At least one of a pair of transparent substrates, a liquid crystal layer sandwiched between the pair of substrates, a video signal electrode disposed on at least one of the pair of substrates, A scanning signal electrode disposed so as to intersect, a thin film transistor disposed near an intersection of the video signal electrode and the scanning signal electrode, a pixel electrode connected to the thin film transistor, and in the same direction as the pixel electrode. A liquid crystal display device having a counter electrode disposed therein and performing display by controlling liquid crystal molecules of the liquid crystal layer with a voltage applied between the pixel electrode and the counter electrode.

The pixel electrode is made of a polycrystalline semiconductor film,

The liquid crystal display device, wherein the counter electrode is made of ITO.

6. The liquid crystal display device according to claim 5, wherein the pixel electrode and the counter electrode are formed in the same layer.

7. At least one pair of transparent substrates, a liquid crystal layer sandwiched between the pair of substrates, a video signal electrode disposed on at least one of the pair of substrates, Scanning signal electrodes arranged so as to intersect, thin film transistors arranged near intersections of the video signal electrodes and the scanning signal electrodes, pixel electrodes connected to the thin film transistors, and arranged in the same direction as the pixel electrodes A liquid crystal display device having a common electrode and a liquid crystal layer that performs liquid crystal display by controlling liquid crystal molecules of the liquid crystal layer with a voltage applied between the pixel electrode and the common electrode.

The pixel electrode is composed of I T O,

The liquid crystal display device, wherein the counter electrode is formed of a polycrystalline semiconductor film.

8. The liquid crystal display device according to claim 7, wherein the pixel electrode and the counter electrode are formed in the same layer.

9. At least one of the transparent substrates is sandwiched between the pair of substrates. A sandwiched liquid crystal layer, a video signal electrode disposed on at least one of the pair of substrates, a scan signal electrode disposed to intersect with the video signal electrode, and the video signal electrode. A thin film transistor arranged near the intersection of the scanning signal electrodes; a pixel electrode connected to the thin film transistor; and a counter electrode arranged in a plane different from the layer on which the pixel electrode is arranged via an insulating film. A liquid crystal display device which performs display by controlling liquid crystal molecules of the liquid crystal layer by a voltage applied between the pixel electrode and the counter electrode,

The pixel electrode is formed of a conductive film containing Si as a main component,

The liquid crystal display device, wherein the counter electrode arranged in a plane is formed of a transparent electrode.

10. A counter substrate and a thin film transistor substrate which face each other with a liquid crystal interposed therebetween; a video signal electrode and a scanning signal electrode which are arranged on the thin film transistor substrate so as to cross each other;

A thin film transistor arranged near an intersection of the scanning signal electrode and the video signal electrode;

A pixel electrode connected to the source of the thin film transistor; and forming an electric field substantially parallel to the thin film transistor substrate between the opposing electrodes connected to the opposing voltage signal line disposed in the same direction as the pixel electrode to form a liquid crystal on the liquid crystal. In a liquid crystal display device that controls transmitted light by applying voltage,

A liquid crystal display device in which at least one of the pixel electrode and the counter electrode is made of a conductive film containing Si as a main component.

11. The liquid crystal display device according to claim 10, wherein said pixel electrode or counter electrode is made of a polycrystalline Si film.

1 2. A counter substrate and a thin film transistor substrate which face each other with a liquid crystal interposed therebetween, A video signal line and a scanning signal line crossing each other on the thin film transistor substrate;

A drain formed near the intersection of the scanning signal line and the video signal line is connected to the video signal line, and a thin film transistor is turned on by the scanning signal line, and a pixel connected to a source of the thin film transistor A liquid crystal display device comprising: an electrode; and an electric field substantially parallel to the thin film transistor substrate formed between the opposing electrodes connected to the opposing voltage signal line, and applied to the liquid crystal to control transmitted light.

A liquid crystal display device, wherein the thin film transistor has a channel made of a polycrystalline Si film, and the pixel electrode or the counter electrode is in the same layer as the channel, and is made of the same conductive film as the channel.

13. Any one of claims 10 to 12, wherein the thin film transistor substrate is made of a polycrystalline Si film and has a built-in circuit for driving a video signal line and a scanning signal line. Liquid crystal display device.

10. The liquid crystal display device according to claim 10, wherein the pixel electrode or the counter electrode is in the same layer as a contact layer of the thin film transistor.

15. The liquid crystal display device according to claim 10, wherein the pixel electrode and the counter electrode are a single-layer amorphous Si film.

16. The liquid crystal according to claim 10, wherein the pixel electrode or the counter electrode includes a silicide of Cr, Mo, W, Ta, Ti, or a composite compound thereof. Display device.

17. The thin-film transistor according to claim 10, wherein the thin-film transistor has a channel made of an amorphous Si film. A liquid crystal display device according to any one of the above.

18. A pair of substrates, at least one of which is transparent, and the liquid sandwiched between the substrates A liquid crystal display device having a crystal layer,

At least one of the pair of substrates has an insulating surface, and a transparent electrode formed on the insulating main surface;

Having at least the patterned semiconductor layer opposed to the transparent electrode via a first insulating layer,

A liquid crystal display device in which the liquid crystal layer is driven by an electric field generated between the patterned semiconductor layer and the transparent electrode.

19. A liquid crystal display device having at least one pair of transparent substrates and a liquid crystal layer sandwiched between the substrates,

A semiconductor layer formed on the first insulating layer, a plurality of thin film transistors including a part of the semiconductor layer and a gate electrode and a pair of first conductive semiconductor layers facing each other with a gate insulating layer interposed therebetween;

A plurality of scanning signal lines connected to the plurality of thin film transistors and formed to cross each other; and a plurality of video signal lines,

At least one of the pair of first conductive type semiconductor layers is patterned and extended on the transparent electrode,

A liquid crystal display device that drives the liquid crystal by an electric field generated between the patterned first conductive type semiconductor layer and the transparent electrode.