JPH07113730B2 - Liquid crystal display - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a liquid crystal display device using a TFT array substrate, and in particular, for improving the quality, it is possible to reduce a short circuit of a charge holding capacitor provided in the TFT array substrate. The present invention relates to a liquid crystal display device having a storage capacitor structure.

[Conventional technology]

A liquid crystal display device is usually constructed by a method in which a display material such as liquid crystal is sandwiched between two opposing substrates and a voltage is applied to the display material. At this time, pixel electrodes arranged in a matrix are provided on at least one substrate, and active elements having non-linear characteristics such as field effect transistors (FETs) are provided for each pixel in order to selectively operate these pixels. ing. Further, a charge storage capacitor is provided for each pixel in order to improve the image quality.

FIG. 12 is a plan view showing one pixel of a TFT array substrate used in the conventional liquid crystal display device disclosed in, for example, Japanese Patent Laid-Open No. 64-26822, and FIG. FIG. 14 is an equivalent circuit diagram of FIG. 12 taken along the line A ′. In the figure,
1 is a source electrode line, 2 is a gate electrode line, 3 is a gate electrode line in the next stage, 4 is a gate insulating film, 5 is a hydrogenated amorphous silicon i layer, 7 is a hydrogenated amorphous silicon n ⁺ layer,
Reference numeral 8 is a drain electrode, 9 is a pixel electrode, 10 is a protective film, 14 is a transparent insulating substrate, 18 is a charge storage capacitor, 19 is a gate wiring pattern of A1, 35 is a liquid crystal, and 38 is a counter electrode.

In the structure shown in FIGS. 12 and 13, first, the gate electrode lines 2 and 3 are formed on the transparent insulating substrate 14 with Cr. Further, the gate wiring pattern 19 of A1 is formed. Then, the gate insulating film 4, the semiconductor film 5, the source electrode line 1, and the drain electrode 8 form a TFT, and the TFT and the pixel electrode 9 form a TFT array. Since the gate electrode line 3 of the next stage has a constant potential except when it is scanned, the gate electrode line 3 and the pixel electrode 9 of the next stage are used to sandwich the gate insulating film 4 by using this. Charge retention capacity by wrapping
Forming 18. A liquid crystal display device is configured by making a counter electrode substrate having a color filter and a transparent conductive film face the TFT array substrate thus configured with a liquid crystal or the like interposed therebetween.

[Problems to be Solved by the Invention]

The conventional liquid crystal display device is configured as described above, and since the gate electrode line in the next stage is used as the charge storage capacitor electrode,
There is a problem in that the charge retention capacity is destroyed and the gate electrode line and the drain electrode are short-circuited, so that the yield is reduced.

The present invention has been made in order to solve the above-mentioned conventional problems, and an object of the present invention is to obtain a liquid crystal display device that can reduce the yield reduction due to the occurrence of a short circuit.

[Means for Solving the Problems]

In the liquid crystal display device according to the present invention, the gate electrode line and the pixel electrode connected to the drain electrode do not directly overlap with each other, and they are capacitively coupled via the floating electrode formed over the gate electrode line and the pixel electrode. Combined,
A plurality of capacitors formed between the floating electrode, the gate electrode line and the pixel electrode are connected in series to provide a charge holding capacitor.

[Action]

According to the present invention, the charge holding capacitor is divided into at least two capacitors in series, and the pixel electrode and the gate electrode line do not directly overlap each other, so that the gate electrode line and the pixel electrode are directly short-circuited. In addition, the occurrence of a short circuit between the gate electrode line and the pixel electrode can be reduced.

[Embodiment] An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a TFT of a liquid crystal display device according to an embodiment of the present invention.
FIG. 2 is a first block diagram showing the plane configuration of one pixel of the array substrate.
FIG. 3 is a sectional view taken along the line AA 'in FIG. 3, and FIG. 3 is a circuit diagram of FIG.
In the figure, 1 is a source electrode line, 2 is a gate electrode line, 3
Is a gate electrode line in the next stage (or the previous stage), 4 is a gate insulating film, 5 is a semiconductor i layer, 6 is an upper insulating film, and 7 is a semiconductor n ^+.
Layer, 8 is drain electrode, 9 is pixel electrode, 10 is protective film, 12
Is a floating electrode, 13 is a dielectric film, 14 is a transparent insulating substrate, and 15 is a TF.
T, 16 are gate-drain parasitic capacitances, 17 is a light-shielding film, 21
Is a charge holding capacity (1), and 22 is a charge holding capacity (2).

Next, a manufacturing method of this embodiment will be described.

First, a transparent conductive film such as ITO is deposited on the transparent insulating substrate 14 such as glass by the EB evaporation method. After that, unnecessary portions of the transparent conductive film are removed by a method such as photoetching to form the floating electrode 12 in an island shape. Next, a dielectric film 13 made of silicon nitride, silicon oxide, tantalum oxide, or any two or more layers thereof is formed by a plasma CVD method, a sputtering method, or the like.

After that, a transparent conductive thin film such as ITO is formed by a sputtering method or the like. After that, the pixel electrode 9 is formed by photoetching or the like. At this time, the floating electrode 12 and the pixel electrode 9 are overlapped while sandwiching the dielectric film 13 to form the charge storage capacitor (1) 21.

Next, a metal such as Cr or Mo is deposited by a sputtering method or the like. After that, the gate electrode lines 2 and 3 are formed by photoetching or the like. At this time, the floating electrode 12 and the gate electrode line 3 are overlapped while sandwiching the dielectric film 13 to form the charge storage capacitor (2) 22.

Next, the gate insulating film 4 such as silicon nitride, the semiconductor i layer 5 such as hydrogenated amorphous silicon i layer, and the upper insulating film 6 are continuously deposited by plasma CVD or the like. Then, the upper insulating film 6 is patterned. Next, the semiconductor n ⁺ layer 7 such as hydrogenated amorphous silicon n ⁺ layer is plasma-treated.
After forming by the CVD method or the like, pattern processing is performed to form a contact hole between the pixel electrode 9 and the drain electrode 10.
Then, a conductive thin film such as A1 and Mo is deposited by a sputtering method or the like, and the source electrode line 1 and the drain electrode 8 are patterned. Furthermore, unnecessary semiconductor n ⁺ layer 7 and unnecessary semiconductor i layer 5
Is etched off with a dry etching layer, and finally a silicon nitride film, a silicon oxide film or the like is deposited by a plasma CVD method or the like, and patterned to form a protective film 10.

A liquid crystal display device is manufactured by sandwiching a display material such as liquid crystal between the TFT array substrate formed as described above and a counter electrode substrate having a transparent electrode, a color filter and the like.

As described above, in this embodiment, the pixel electrode is arranged so as not to overlap with the gate electrode of the previous stage or the next stage, and the floating electrode extending over the pixel electrode and the gate electrode is provided, and the floating electrode, the pixel electrode, and Since the pixel electrode and the gate electrode are capacitively coupled by the series coupling of the capacitance formed between the floating electrode and the gate electrode, the floating electrode and the pixel electrode, or the floating electrode and the gate electrode are connected. Even if a short circuit occurs in either of them, a short circuit between the gate and drain does not occur. Therefore, a decrease in yield due to a short circuit between the pixel electrode and the gate electrode line can be reduced.

In the above-described embodiment, the case where the upper insulating film 6 is used in the TFT structure is shown, but the TFT structure shown in FIGS. 4 and 5 may be a TFT structure in which the upper insulating film is not used.

Further, in the above embodiment, the floating electrode 12 was first formed and the dielectric film 13 was used. However, as shown in FIGS. 6, 7 or 8 and 9, The floating electrode 12 is formed by using a source / drain electrode material, and the floating electrode 12, the gate electrode line 3, the pixel electrode 9 and the gate insulating film 4 form a charge holding capacitor (1) 21 and a charge holding capacitor (2) 22. You can also do it. It is also possible to provide both of the above.

Further, in the above embodiment, the case where the number of the floating electrodes 12 is one is shown, but a plurality of floating electrodes 12 may be provided as shown in FIG. For example, when the number of floating electrodes 12 is four in FIG. 1, the structure is as shown in FIG.

〔The invention's effect〕

As described above, according to the present invention, the charge storage capacitor formed between the gate electrode line and the pixel electrode is configured without the gate electrode line and the pixel electrode overlapping each other. This has the effect of reducing the occurrence of short circuits. In addition, since the charge storage capacitor is formed by a plurality of capacitors in series, even if one of them is short-circuited, there is an effect that it is possible to provide redundancy that the charge storage capacitor is established.

[Brief description of drawings]

FIG. 1 is a plan view showing one pixel of a TFT array substrate of a liquid crystal display device according to an embodiment of the present invention, and FIG. 2 is an A- line in FIG.
A'section view, FIG. 3 is a circuit diagram of FIG. 1, FIG. 4, and FIG.
8 and 9 show a liquid crystal display device according to another embodiment of the present invention.
A plane configuration diagram showing one pixel of the TFT array substrate, FIG. 5,
7 and 9 are A- in FIGS. 4, 6 and 8, respectively.
A'sectional view, FIG. 10 is a circuit diagram in the case of having a plurality of floating electrodes in another embodiment of the present invention, and FIG. 11 is a plan configuration diagram in the case of FIG. 10 having four floating electrodes. , First
12 is a plan view showing one pixel of a TFT array substrate of a conventional liquid crystal display device, FIG. 13 is a sectional view taken along the line AA ′ of FIG. 12,
FIG. 14 is an equivalent circuit diagram of FIG. 1 ... Source electrode line, 2 ... Gate electrode line, 3 ... Next (or previous) gate electrode line, 4 ... Gate insulating film, 8 ... Drain electrode, 9 ... Pixel electrode, 12 ... Floating electrode, 13 ... Dielectric film, 14 ... Transparent insulating substrate, 15 ... TF
T, 23 ... Charge holding capacitance 1, 22 ... Charge holding capacitance 2, 35
……liquid crystal. The same reference numerals in the drawings indicate the same or corresponding parts.

Front page continuation (72) Inventor Yoshinori Numano 8-1-1 Tsukaguchihonmachi, Amagasaki City, Hyogo Sanryo Electric Co., Ltd. Materials Research Center (72) Inventor Masahiro Hayama 8-1-1 Tsukaguchihonmachi, Amagasaki City, Hyogo Prefecture Materials Research Laboratory, Sanryo Electric Co., Ltd. (56) Reference JP-A-57-32484 (JP, A)

Claims (1)

[Claims] 1. A plurality of gate electrode lines arranged in parallel on a transparent insulating substrate, a plurality of source electrode lines intersecting with the gate electrode lines, and thin film transistors provided at intersections of the electrode lines (hereinafter abbreviated as TFT). ), And a TFT array substrate having a pixel electrode connected to the drain of the TFT, a counter electrode substrate provided to face the TFT array substrate, and sandwiched between the counter electrode substrate and the TFT array substrate. In the liquid crystal display device having a liquid crystal display material, the pixel electrode is arranged without directly overlapping with a gate electrode line at the next stage or the previous stage of the TFT provided with the pixel electrode. Partially overlaps the gate electrode line of the stage or the previous stage and the pixel electrode, and forms a capacitor between the gate electrode line of the next stage or the previous stage and the pixel electrode, respectively. As such, and a liquid crystal display device characterized by comprising the placed floating electrode so as not to overlap with the TFT and the source electrode line.