JPH10170955A - Liquid crystal display device and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal display device and its manufacturing method that eliminates the need of a dedicated power source or applying a voltage to an FID(field induced drain) electrode and the need of an FID bus line extending to the outside of a display area, and can simplify the manufacture process, as to a liquid crystal display device, which has TFTs in the FID structure and its manufacturing method. SOLUTION: A polysilicon film, which forms the source and drain of a TFT 31 and a polysilicon film, which forms a diode 30 are formed at the same time. Further, the FID electrode 24 and the FID bus line 25 are formed at the same time and the FID bus line 25 connects the cathode of a diode 30 to the FID electrode 24 and the anode to a gate bus line 16b.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an active matrix type liquid crystal display device and a method of manufacturing the same, and more particularly to a TFT (Thin FF) having an FID (Field Induced Drain) structure.
The present invention relates to a liquid crystal display device using an ilm transistor and a method for manufacturing the same.

[0002]

2. Description of the Related Art An active matrix type liquid crystal display device is provided with a switch which is turned off when not selected and cuts off a signal in each pixel to prevent crosstalk. It shows excellent display characteristics as compared with. In particular, T as a switch
A liquid crystal display device using an FT (hereinafter referred to as a TFT liquid crystal display device) has a high driving capability of a TFT.
(Cathode-Ray Tube). Then, a liquid crystal display device incorporating a driver circuit for driving the TFT has been developed, and is used as a high resolution and high precision liquid crystal display device.

Generally, a liquid crystal display device has a structure in which liquid crystal is sealed between two transparent substrates. Of the two surfaces (opposing surfaces) of the transparent substrate facing each other, a counter electrode, a color filter, an alignment film, and the like are formed on one surface side, and an active matrix circuit and a pixel are formed on the other surface side. An electrode, an alignment film, and the like are formed. further,
A polarizing plate is attached to a surface of the transparent substrate opposite to the opposite surface. These two polarizing plates are arranged, for example, such that the polarization axes of the polarizing plates are orthogonal to each other. According to this, a mode in which light is transmitted when no electric field is applied and light is blocked when an electric field is applied, That is, a normally white mode is set. On the contrary, when the polarization axes of the two polarizing plates are parallel, a normally black mode is set.

[0004] In a TFT liquid crystal display device, it is necessary that the off-state current of the TFT be low in order to maintain a voltage applied between the pixel electrode and the counter electrode. Therefore, in a TFT liquid crystal display device, an LDD (Lightly Dope
s Drain) structure TFT and source /
A TFT having an FID structure provided with an FID electrode for controlling a resistance between drains is used.

FIG. 18 is a top view showing a conventional liquid crystal display device having a TFT having an FID structure, and FIG.
It is sectional drawing of the T part. In FIG. 18, illustration of the interlayer insulating film is omitted. S on the entire surface of the glass substrate 51
An underlying protective film 52 made of iO ₂ is formed, and a plurality of gate bus lines 56 are formed on the underlying protective film 12.
And a plurality of drain bus lines 66 are arranged to be orthogonal to each other when viewed from above. In each rectangular area divided by the gate bus line 56 and the drain bus line 66, a pixel electrode 68 made of ITO (indium tin oxygen) and a TFT 71 are formed.

As shown in FIG. 19, a TFT 71 is formed of a polysilicon film 53 selectively formed on a base protection film 52.
And a gate insulating film 54 selectively formed on the polysilicon film 53, and a gate electrode 56a formed on the gate insulating film 54. Impurities are introduced at a high concentration into both ends of the polysilicon film 53 which are not covered with the gate insulating film 54, and serve as a source and a drain. Note that the side and top surfaces of the gate electrode 56a are covered with an oxide film 57. Also,
The gate electrode 56a is electrically connected to a gate bus line 56 formed on the underlying protective film 52.

An interlayer insulating film composed of a SiO ₂ film 58 and a SiN film 59 is formed on the underlying protective film 52 so as to cover the TFT 71. An FID electrode 64 and a drain bus line 66 are formed on the SiN film 59. The FID electrode 64 is arranged above a region between the source and the drain of the TFT 71. Further, the drain bus line 66 is connected to the T bus via the contact hole 63a.
It is electrically connected to the drain of FT71.

The SiN film 67 is formed on the SiN film 59 so as to cover the FID electrode 64 and the drain bus line 66.
Is formed. And this S
The pixel electrode 68 and the FID bus line 65 are formed on the iN film 67.
Are formed. The pixel electrode 68 is in the contact hole 7
0a and the source of the TFT 71 via the contact hole 63b.
Reference numeral 5 is electrically connected to the FID electrode 64 via the contact hole 70b.

An alignment film (not shown) is formed on the SiN film 67 and the pixel electrode 68. Further, a glass substrate (not shown) on which a counter electrode, a color filter, and an alignment film are formed is disposed facing the glass substrate 51, and a liquid crystal (not shown) is interposed between these substrates. A polarizing plate (not shown) is disposed outside each of these glass substrates.

In the conventional liquid crystal display device thus configured, a constant voltage is applied to the FID electrode 64 from a power supply (not shown) via the FID bus line 65. Then, the electric field generated from the FID electrode 64 causes the gate insulating film 5 not covered by the gate electrode 56a.
4, carriers are generated in the portion of the polysilicon film 53 below,
The sheet resistance of the polysilicon film 53 is 10 ⁵ to 10 ⁶ Ω /
cm ^2, and the off-state current of the TFT 71 is reduced.
As a result, a decrease in charges accumulated in the pixel electrode 68 is avoided, and good display performance is obtained.

[0011]

However, the above-described liquid crystal display device provided with the conventional FID structure TFT has the following disadvantages. That is, the conventional liquid crystal display device requires a dedicated power supply for applying a voltage to the FID electrode 64. Further, an FID bus line 65 for connecting the FID electrode 64 to the dedicated power supply formed outside the display area is required, and the circuit configuration becomes complicated.

Further, in the conventional liquid crystal display device, it is necessary to form the FID electrode 64 and the FID bus line 65 individually, and the manufacturing process is complicated. FID electrode 64 is FI
It is conceivable to simplify the manufacturing process by forming it on the SiN film 67 similarly to the D bus line 65.
As the distance between the ID electrode 64 and the polysilicon film 53 increases, it is necessary to increase the voltage applied to the FID electrode 64, which causes a new problem that power consumption increases.

An object of the present invention is to provide a liquid crystal display device which does not require a dedicated power supply for applying a voltage to the FID electrode and does not require an FID bus line extending outside the display area, thereby simplifying the manufacturing process and a liquid crystal display device therefor. It is to provide a manufacturing method.

[0014]

An object of the present invention is to provide a transparent substrate, a plurality of gate bus lines arranged in parallel with each other on the transparent substrate, and a plurality of gate bus lines intersecting the gate bus line on the transparent substrate. A plurality of drain bus lines, a pixel electrode disposed in each rectangular region surrounded by the gate bus line and the drain bus line, and a drain bus line connected between the drain bus line and the pixel electrode. A thin film transistor having a gate electrode connected to the gate bus line, a FID electrode disposed above the gate electrode of the thin film transistor,
The problem is solved by a liquid crystal display device having an electrode and a diode connected between the gate bus line or the drain bus line.

The object of the present invention is to form a silicon film over the entire surface of a transparent substrate, and to etch the silicon film to obtain first and second island-shaped silicon films separated from each other. Selectively forming a first insulating film on the first silicon film; forming a gate electrode on the first insulating film and forming a gate bus line connected to the gate electrode; Selectively introducing impurities into the first and second silicon films to form a source and a drain in the first silicon film and forming a diode in the second silicon film; Forming an interlayer insulating film covering the diode and the gate electrode over the entire surface of the substrate, selectively forming a contact hole in the interlayer insulating film, and filling the contact hole. A conductive film is formed on the entire surface of the interlayer insulating film in such a manner that the FID electrode, the diode, the FID electrode, and the gate bus are disposed above the gate electrode by selectively etching the conductive film. Forming a FID bus line connected to a line and a drain bus line connected to the drain region.

Hereinafter, the operation of the present invention will be described. In the present invention, the FID electrode is connected to the gate bus line via a diode. When a voltage is applied to the gate bus line, charges are accumulated in the FID electrode via the diode, and carriers in the silicon film below the gate insulating film in a portion not covered by the gate electrode due to an electric field generated from the FID voltage. The concentration increases, the resistance of the non-doped silicon film under the gate insulating film decreases, and thereby the electric field concentrated portion between the channel and the drain electrode is relaxed, so that the off current of the TFT is reduced. When no voltage is applied to the gate bus line, the charge stored in the FID electrode by the diode is prevented from leaking. As a result, the liquid crystal display device of the present invention
Dedicated power supply for supplying voltage to ID electrode, and FID
Wiring and the like for connecting the electrode and the dedicated power source are not required, and the circuit configuration is simplified.

According to the method of the present invention, a first silicon film serving as a source / drain of a TFT and a second silicon film serving as a diode are simultaneously formed, and an FID is formed.
The electrodes, the gate bus lines and the FID bus lines are formed simultaneously. This makes it possible to manufacture the above-described liquid crystal display device while avoiding an increase in the number of manufacturing steps. Note that, when polysilicon is used as a silicon film to be a TFT and a diode, carrier mobility is higher and high-speed operation becomes possible as compared with the case where amorphous silicon is used. For this reason, it is preferable that the silicon film is made of polysilicon.

[0018]

Embodiments of the present invention will be described below with reference to the accompanying drawings. (First Embodiment) FIG. 1 is a top view showing a liquid crystal display device according to a first embodiment of the present invention, and FIG. 2 is a TFT 31 shown in FIG.
FIG. 3 is a sectional view of a portion of the diode 30 in FIG. In FIG. 1, illustration of the interlayer insulating film is omitted.

An underlying protective film 12 made of SiO ₂ is formed on the entire surface of the glass substrate 11, and a plurality of gate bus lines 16b arranged in parallel with each other are formed on the underlying protective film 12. A plurality of drain bus lines 26 arranged orthogonally to these gate bus lines 16b are formed. These gate bus lines 1
6b and a plurality of rectangular regions divided by the drain bus line 26 respectively include a diode 30 and a TF
T31 and the pixel electrode 28 are formed.

As shown in FIG. 2, the TFT 31 has a polysilicon film 13a selectively formed on the underlying protective film 12.
An insulating film (gate insulating film) 14 formed on the central portion of the polysilicon film 13a; a gate electrode 16a selectively formed on the insulating film 14; _The FID electrode 24 is formed via an interlayer insulating film composed of the _two films 18 and the SiN film 19. The gate electrode 16a is connected to a gate bus line 16b. The drain of the TFT 31 is connected to the drain bus line 26 via the contact hole 23a.

The pixel electrode 28 is formed on a SiN film 27 (interlayer insulating film) formed on the SiN film 19.
The pixel electrode 28 is connected to the source of the TFT 31 via a contact hole 26 selectively formed in the SiN film 27 and a contact hole 23b selectively formed in the SiN film 19 and the SiO ₂ film 18. Further, as shown in FIG. 3, the diode 30 is constituted by a polysilicon film 13b selectively formed on the underlying protective film 12. One end side (cathode side) of this diode 30
Is the FI of the TFT 31 through the contact hole 23c and the FID bus line 25 formed on the SiN film 19.
It is connected to the D electrode 24. The other end (anode side) of the diode 30 is connected to the FID bus line 25 via a contact hole 23d.
The bus line 25 is a gate bus line 16b of an adjacent pixel.
(The gate bus line 16b to which the gate electrode 16a of the TFT 3 of the adjacent pixel is connected) via the contact hole 23e.

The side and top surfaces of the gate electrode 16 and the gate bus line 16b are covered with an oxide film 17. An alignment film is formed on the SiN film 27 and the pixel electrode 28. Further, a glass substrate (not shown) on which a counter electrode, a color filter, and an alignment film are formed is disposed to face the glass substrate 11, and a liquid crystal (not shown) is sealed between these substrates. Further, a polarizing plate (not shown) is disposed outside each of these glass substrates.

In this embodiment, the FID electrode 24 is connected to the gate bus line 16b via the diode 30, and charges are accumulated in the FID electrode 24 by the voltage supplied to the gate bus line 16b. The electric field generated by the electric charge accumulated in the FID electrode 24 causes the gate insulating film 14 not covered by the gate electrode 16a to be covered.
Carriers are generated in the portion of the polysilicon film 13a underneath, the sheet resistance of the polysilicon film 13a in this portion is reduced, the electric field concentration portion between the channel and the drain electrode is relaxed, and the off current of the TFT 30 is reduced. Reduced. Therefore, a dedicated power supply for supplying a voltage to the FID electrode 24 and a wiring extending from the FID electrode 34 to the outside of the display area, which are required in the related art, are not required, and an effect that the circuit configuration is simplified can be obtained.

FIGS. 4 to 10 are sectional views showing a method of manufacturing the above-described liquid crystal display device in the order of steps, and FIGS. 11 to 15 are top views in the middle of manufacturing. 11 to 15, illustration of the interlayer insulating film is omitted. First, as shown in FIG. 4, a 200-nm-thick underlying protective film 12 made of SiO ₂ is formed on a glass substrate 11 by using a plasma CVD method, and then an amorphous silicon film 13 is formed to a thickness of 50 nm.
Formed to a thickness of At this time, monosilane and N ₂ O gas are used for forming the underlying protective film 12, and monosilane and hydrogen gas are used for forming the amorphous silicon film 13.

Thereafter, the amorphous silicon film 13 is irradiated with an excimer laser to change the amorphous silicon into polysilicon, thereby forming a polysilicon film.
Thereafter, the polysilicon film is selectively etched by dry etching using chlorine gas, and the polysilicon films 13a and 13b are formed into islands only at the portions where the TFT 31 and the diode 30 are formed, as shown in the top view in FIG. The remaining portions of the polysilicon film are removed.

Next, as shown in FIG.
Using a method, an insulating film 14 made of SiO ₂ is formed on the entire surface of the underlying protective film 12 to a thickness of 150 nm. Monosilane and N ₂ O gas are used to form the insulating film 14. Thereafter, an aluminum film 15 having a thickness of 300 nm is formed on the insulating film 14 by a sputtering method. Next, a resist film (not shown) is formed in a predetermined pattern on the aluminum film 15, and the aluminum film 15 is dry-etched using a chlorine-based gas. As shown in the top view, a gate electrode 16a orthogonal to the polysilicon film 13a when viewed from above
And the polysilicon film 1 connected to the gate electrode 16a.
3a and a gate bus line 16b extending in a direction parallel to the gate bus line 16a. Thereafter, an oxide film 17 is formed by anodizing each side surface and upper surface of the gate electrode 16a and the gate bus line 16b using an aqueous solution containing tartaric acid.

Next, as shown in a sectional view of FIG. 7 and a top view of FIG. 13, a resist film for selectively covering the gate electrode 16a and the portions on both sides thereof and the central portion of the polysilicon film 13b by a photoresist method. (Not shown), then C
Etching the gate insulating film 14 with HF ₃ gas,
Gate electrode 15 and parts on both sides thereof and polysilicon film 1
The insulating film 14 is left at the center of 3b. After that, the resist film is removed.

Next, a resist film (not shown) is formed so as to cover the entire surface, and the resist film is exposed so that the polysilicon films 13a and 13b of the portions serving as the source / drain of the TFT 31 and the cathode of the diode 30 are exposed. Pattern the film. Note that the step of etching the gate insulating film 14 and the step of selectively exposing the polysilicon films 13a and 13b may be combined.

Then, as shown in FIG. 8A, a cross-sectional view of the TFT portion, and FIG. 8B, a cross-sectional view of the diode portion, the polysilicon film 13a and the polysilicon film 13a are formed by an ion doping method using PH ₃ gas, for example. Phosphorus (P) ions are implanted at a high concentration into 13b to form n-type impurity regions 131 and 132 serving as source / drain and an n-type impurity region 133 serving as a cathode of the diode 30. After that, the resist film is removed.

Next, a resist film (not shown) covering the entire surface is formed, and the resist film is patterned so that the polysilicon film 13b at the portion serving as the anode of the diode 30 is exposed. Thereafter, the acceleration voltage is increased by ion doping using B ₂ H ₆ gas, and B ions are implanted into the polysilicon film 13b to form the low concentration p-type impurity region 134.
Is formed, and B ions are implanted into the polysilicon film 13b at a reduced acceleration voltage to form a high-concentration p-type impurity region 135. Then, after removing the resist film, the polysilicon films 13a and 13b are irradiated with excimer laser to activate the impurity regions 131 to 135. Thus, T
Source / drain of FT31 and pn of diode 30
Form a bond.

Note that these impurity regions 131 to 135
Of the peripheral circuit (driver circuit, etc.)
It is preferable to form an element such as S. This allows
An increase in the number of steps caused by forming the diode 30 can be avoided. Next, as shown in FIG. 9A, a cross-sectional view of a TFT portion, FIG. 9B, a cross-sectional view of a diode portion, and FIG. SiO ₂ film 18 having a thickness of 30 nm and a thickness of 37
A 0 nm SiN film 19 is continuously formed. At this time,
Monosilane and N ₂ O gas are used for forming the SiO ₂ film 18, and monosilane and ammonia gas are used for forming the SiN film 19.

Thereafter, a resist film (not shown) having a predetermined contact hole forming region opened is formed by a photoresist method, and the SiN film 19 exposed inside the resist opening is formed by dry etching using a fluorine-based gas. Etching is performed, and the underlying SiO ₂ film is etched with BHF. Further, the anodic oxide film 17 on the surface of the gate bus line 16b exposed inside the resist opening is etched with a mixed solution of chromium oxide and phosphoric acid. In this manner, the impurity regions 131-1 are removed from the surface of the SiN film 19.
Contact holes 23a to 23d reaching 35,
A contact hole 23e reaching the gate bus line 16b from the surface of the SiN film 19 is formed.

Next, the thickness is 50 nm by sputtering.
Ti film, Al film with a thickness of 200 nm and thickness of 100
By continuously forming a Ti film of nm in this order from the lower side, a conductive film composed of these laminated films is formed on the SiN film 19, and the contact holes 23a to 23e are filled with the conductive film material. Thereafter, a resist film (not shown) is formed in a predetermined pattern on the conductive film, and the conductive film is etched with a chlorine-based gas.
FIG. 15B is a cross-sectional view of the diode portion, and FIG. 15 is a top view of the FID electrode 24 disposed above the gate electrode 16a.
Is formed, and a drain bus line 26 connected to the drain of the TFT 31 is formed. After that, the resist film is removed.

Next, as shown in FIGS. 1 to 3, a SiN film 27 having a thickness of 300 nm is formed as an interlayer insulating film on the entire surface by using a plasma CVD method. At this time, SiN
For forming the film 27, monosilane and ammonia gas are used. Then, a resist film (not shown) having an opening is selectively formed only on the contact hole 23b by a photoresist method, and the contact hole 26 is formed using a fluorine-based gas. Thereafter, after removing the resist film, an ITO film is formed on the entire surface so as to fill the contact holes 26 by a sputtering method. Then, a resist film (not shown) that selectively covers the pixel electrode formation region on the ITO film is formed, and the ITO film is etched with a hydrobromic acid aqueous solution to form the pixel electrode 28.
After that, the resist film is removed. Thus, the liquid crystal display device of the present embodiment is completed.

According to the above-described method of manufacturing a liquid crystal display device,
The TFT 31 and the diode 30 are formed simultaneously and the FID
Since the electrode 24 and the FID bus line 25 are formed at the same time, an increase in the number of manufacturing steps can be avoided. Further, a liquid crystal display device having a TFT with a small off-state current and excellent display performance can be easily manufactured. (Second Embodiment) FIG. 16 is a top view showing a liquid crystal display device according to a second embodiment of the present invention. Note that FIG.
In FIG. 1, the same components as those in FIG.

In this embodiment, the diode 30
Is connected to the gate bus line 16b to which the gate electrode 16a of the TFT 31 in the same pixel is connected via the FID bus line 25a and the contact hole 35. In the second embodiment, the same effects as in the first embodiment can be obtained.

(Third Embodiment) FIG. 17 is a top view showing a liquid crystal display device according to a third embodiment of the present invention.
17, the same components as those in FIG. 1 are denoted by the same reference numerals, and detailed description thereof will be omitted. In the present embodiment, the anodes of the diodes 30 of a plurality of pixels arranged in the direction in which the drain bus line 26 extends are electrically connected by the FID bus line 36, and the FID bus line 36 is connected via the contact hole 37. Are electrically connected to the respective gate bus lines 16b.

In the third embodiment, the same effect as in the first embodiment can be obtained. Note that the first
In each of the third to third embodiments, a liquid crystal display device having an n-type TFT has been described. However, the present invention can be applied to a liquid crystal display device having a p-type TFT.
In this case, the anode side of the diode is connected to the FID electrode, and the cathode side is connected to the drain bus line.

In the first to third embodiments, the case where the diode is connected to the gate bus line has been described. However, the diode may be connected to the drain bus line.

[0040]

As described above, in the liquid crystal display device of the present invention, since the FID electrode is connected to the gate bus line via the diode, the charge is applied to the FID electrode by the voltage applied to the gate bus line. Is accumulated,
The sheet resistance of a part of the non-doped layer of the source / drain of the TFT is appropriately reduced, and the concentration of the electric field is alleviated.
The off-state current of T is reduced. This eliminates the need for a dedicated power supply for applying a voltage to the FID electrode and a wiring for connecting the power supply and the FID electrode, which are conventionally required, and has the effect of simplifying the circuit configuration. .

According to the method of manufacturing a liquid crystal display device of the present invention, the first silicon film serving as the source / drain of the TFT and the second silicon film serving as the diode are simultaneously formed, and the FID electrode is formed. And the gate bus line and F
Since the ID bus line and the ID bus line are formed at the same time, the liquid crystal display device having the above structure can be manufactured without increasing the number of manufacturing steps.

[Brief description of the drawings]

FIG. 1 is a top view illustrating a liquid crystal display device according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view of a TFT portion of the liquid crystal display device according to the first embodiment.

FIG. 3 is a sectional view of a diode part of the liquid crystal display device according to the first embodiment.

FIG. 4 is a cross-sectional view (part 1) illustrating the method for manufacturing the liquid crystal display device of the first embodiment.

FIG. 5 is a sectional view (part 2) illustrating the method for manufacturing the liquid crystal display device of the first embodiment.

FIG. 6 is a sectional view (part 3) illustrating the method for manufacturing the liquid crystal display device of the first embodiment.

FIG. 7 is a sectional view (part 4) illustrating the method for manufacturing the liquid crystal display device of the first embodiment.

FIG. 8 is a sectional view (part 5) illustrating the method for manufacturing the liquid crystal display device of the first embodiment.

FIG. 9 is a sectional view (part 6) illustrating the method for manufacturing the liquid crystal display device of the first embodiment.

FIG. 10 is a sectional view (part 7) illustrating the method for manufacturing the liquid crystal display device of the first embodiment.

FIG. 11 is a plan view (part 1) illustrating the method for manufacturing the liquid crystal display device of the first embodiment.

FIG. 12 is a plan view (part 2) illustrating the method for manufacturing the liquid crystal display device of the first embodiment.

FIG. 13 is a plan view (part 3) illustrating the method for manufacturing the liquid crystal display device of the first embodiment.

FIG. 14 is a plan view (part 4) illustrating the method for manufacturing the liquid crystal display device of the first embodiment.

FIG. 15 is a plan view (part 5) illustrating the method for manufacturing the liquid crystal display device of the first embodiment.

FIG. 16 is a top view illustrating a liquid crystal display device according to a second embodiment of the present invention.

FIG. 17 is a top view illustrating a liquid crystal display device according to a third embodiment of the present invention.

FIG. 18 is a top view showing a conventional liquid crystal display device having an FID structure FET.

FIG. 19 is a sectional view of a TFT portion of a conventional liquid crystal display device.

[Explanation of symbols]

11,51 glass substrate 12,52 underlayer protective film 13a, 13b polysilicon film 14 insulating film 15 aluminum film 16a, 56a gate electrode 16b, 56 gate bus line 17,57 oxide film 18,58 SiO ₂ film 19,27,59 , 67 SiN films 23a to 23e, 26, 36, 63a, 63b, 70
a, 70b Contact hole 24, 64 FID electrode 25, 36, 65 FID bus line 26, 66 Drain bus line 28, 68 Pixel electrode 30 Diode 31, 71 TFT

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Tomotaka Matsumoto 4-1, 1-1 Kamidadanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture Inside Fujitsu Co., Ltd. (72) Inventor Tsutomu Tanaka 4 Kamikadanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture Chome 1-1 No. Fujitsu Co., Ltd.

Claims (6)

[Claims] 1. A transparent substrate; a plurality of gate bus lines arranged in parallel with each other on the transparent substrate; and a plurality of drain buses arranged on the transparent substrate so as to intersect with the gate bus lines. A pixel electrode disposed in each rectangular area surrounded by the gate bus line and the drain bus line; and a pixel electrode connected between the drain bus line and the pixel electrode, wherein the gate electrode is connected to the gate bus line. A FID electrode disposed above the gate electrode of the thin film transistor; and a diode connected between the FID electrode and the gate bus line or the drain bus line. Liquid crystal display device. 2. The liquid crystal display device according to claim 1, wherein the diode is connected to a gate bus line to which a gate electrode of a thin film transistor in an adjacent rectangular area is connected. 3. The liquid crystal display device according to claim 1, wherein the diode is connected to a gate bus line to which a gate electrode of a thin film transistor in the same rectangular area is connected. 4. An FID bus line extending in a direction parallel to the drain bus line, and a plurality of diodes arranged along the FID bus line are electrically connected to each other by the FID bus line. The liquid crystal display device according to claim 1, wherein: 5. A step of forming a silicon film on the entire surface of a transparent substrate and etching the silicon film to obtain first and second island-shaped silicon films separated from each other; Selectively forming a first insulating film on the film; forming a gate electrode on the first insulating film and forming a gate bus line connected to the gate electrode; And selectively introducing an impurity into the second silicon film to form a source and a drain in the first silicon film and to form a diode in the second silicon film. Forming an interlayer insulating film covering the diode and the gate electrode on the entire surface, selectively forming a contact hole in the interlayer insulating film, and filling the contact hole. Forming a conductive film on the entire surface of the interlayer insulating film, and selectively etching the conductive film to form an FID electrode, the diode, the FID electrode, and the gate bus disposed above the gate electrode. Forming a FID bus line connected to a line and a drain bus line connected to the drain region. 6. The method according to claim 5, wherein the first and second silicon films are made of polysilicon.