JP2001255549A - Liquid crystal display - Google Patents

Abstract

(57) [Problem] To provide a liquid crystal display device which can be manufactured with a high yield, in which dielectric breakdown due to electric discharge is suppressed in a manufacturing process. In a liquid crystal display device according to the present invention, a liquid crystal layer is sandwiched between a pair of substrates, and one of the pair of substrates is provided with pixel electrodes arranged in a matrix and each row of the pixel electrodes. And a common electrode which is provided correspondingly and forms a storage capacitor in opposition to each of the pixel electrodes in each row. The common electrode is electrically connected to a first common electrode signal supply line. When the common electrode and the first common electrode signal supply line are electrically separated from each other, the charge concentration at the first end of the common electrode close to the first common electrode signal supply line is suppressed. As a result, the common electrode and the first common electrode signal supply line overlap with each other via an insulating film near the first end of the common electrode.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a liquid crystal display, and more particularly to an active matrix type liquid crystal display.

[0002]

2. Description of the Related Art A display device to which liquid crystal is applied has characteristics that are not seen in conventional display devices, such as low power driving and light weight. In particular, a thin film transistor (Thin Film Transistor) is used as a switching element in each pixel.
r, hereinafter referred to as “TFT”. The active matrix type liquid crystal display device in which) is arranged is used for a display of a notebook computer, a car navigation system, and the like because a clear image display with little crosstalk can be obtained, and is rapidly used as a large display monitor in recent years. It has become.

In general, an active matrix type liquid crystal display device is configured such that an active matrix substrate provided with pixel electrodes and switching elements and a counter substrate provided with a counter electrode are arranged so as to face each other via a liquid crystal layer. You. FIG. 3 is a partial plan view of the active matrix substrate 100 included in the conventional liquid crystal display device 700, and FIGS. 4 and 5 are respectively BB ′ and CC ′ of the active matrix substrate 100 of FIG. FIG. 10 is a cross-sectional view of a corresponding liquid crystal display device 700. Hereinafter, FIGS. 3 and 4
A conventional liquid crystal display device 700 will be described with reference to FIG.

The liquid crystal display device 700 includes an active matrix substrate 100, a counter substrate 400, and a liquid crystal layer 300 sandwiched between these substrates.

As shown in FIG. 3, an active matrix substrate 100 includes a scanning signal supply line 2 arranged in a row direction, a video signal supply line 5 arranged in a column direction, and these wirings 2 and 5 and a TFT 20. The pixel electrodes 10 arranged in a matrix and connected via the same, a common electrode 56 provided corresponding to each row of the pixel electrodes 10, and a first and second common electrode signal supply electrically connected to the common electrode 56 It has lines 12 and 8. The common electrodes 56 face the pixel electrodes 10 in the corresponding row, respectively, and form a storage capacitor between the common electrodes 56 and the pixel electrodes 10. As shown in FIG. 5, the TFT 20 includes a gate electrode 32 formed on the substrate 1, a semiconductor layer 4 formed on the gate electrode 32 via the insulating film 3,
It has a source electrode 35 and a drain electrode 9 electrically connected to the semiconductor layer 4.

The scanning signal supply line 2 is supplied with an address signal, and the video signal supply line 5 is supplied with a video display signal whose polarity is inverted every frame scanning period. This video display signal is written to the capacitance of each pixel via the TFT 20 which is a switching element which is turned on / off by an address signal and controlled. The liquid crystal layer 3 on each pixel electrode is generated by a potential difference between the pixel electrode voltage and the voltage supplied to the counter electrode.
00 is excited, the orientation of the liquid crystal molecules contained in the liquid crystal layer 300 is arbitrarily changed, and the light transmittance is adjusted to produce a desired image. Writing to the pixel electrode is performed by the video signal supply line 5
Are simultaneously supplied to the scanning signal supply line 2 by sampling the address signals sequentially. The display signal written to the pixel electrode (capacitance) is stored by the storage capacitor formed between the pixel electrode 10 and the common electrode 56 until the next frame scan, and the potential is maintained. As described above, the liquid crystal display device 70
0 drives.

Next, a method of manufacturing the active matrix substrate 100 will be briefly described. First, a TFT 2 is provided on a substrate 1.
The scanning signal supply line 2, the second common electrode signal supply line 8, and the common electrode 56 which also function as the zero gate electrode 32 are formed, and the insulating film 3 is deposited thereon (see FIGS. 3 to 5). The common electrode 56 and the second common electrode signal supply line 8 are formed in the same process, and the second end 24 of the common electrode 56 forms a comb-shaped electrode connected to the second common electrode signal supply line 8. As shown in FIG. 3, the comb-shaped electrode occupies a large area on the active matrix substrate 100 from outside the pixel region to inside the pixel region. The “pixel region” refers to a region that contributes to display, in which pixel electrodes 10 and TFTs 20 formed in a later process are arranged in a matrix on a substrate.

Next, a semiconductor layer 4 for forming the source, drain and channel regions of the TFT 20 is formed (see FIG. 5). Further, the video signal supply line 5 and the source electrode 35, the drain electrode 9, and the first common electrode signal supply line 12 extending therefrom are formed (see FIGS. 3 to 5). The first common electrode signal supply line 12 is connected to the common electrode 5
6 are provided close to each other with a small line space S (see FIG. 4) interposed therebetween via the first end portion 22 and the insulating film 3.

Further, an insulating film 6, which is a passivation film covering the TFT 20, is formed, and portions corresponding to the contact holes 7, 70 and 72 are removed (see FIGS. 4 and 5). A contact hole 7 is formed on the insulating film 6.
To form a pixel electrode 10 connected to the drain electrode 9 through the substrate. At the same time, a connecting portion 13 for connecting the first end 22 side of the common electrode 56 and the first common electrode signal supply line 12 via the contact holes 70 and 72 is formed on the insulating film 6 ( (See FIG. 4). The active matrix substrate 100 is manufactured as described above.

[0010]

In the manufacturing process of a liquid crystal display device, the substrate may be charged. In particular, the substrate is exposed to an electric field in a general film forming method such as a sputtering process, a CVD (chemical vapor deposition) process, a photolithography process, and a dry etching process, or is peeled and charged during transportation, The substrate is easily charged.

In the conventional liquid crystal display device 700 described above, the first common electrode signal supply line 12 is close to the first end 22 side of the common electrode 56 with a small line space S (see FIG. 4). Provided. Therefore, in the manufacturing process of the liquid crystal display device 700, if the above-described substrate charging occurs in a state where the first common electrode signal supply line 12 and the common electrode 56 are separated, the vicinity of the first end 22 of the common electrode 56 The charges are attracted to the common electrode 5 and the charge amount is concentrated, and the common electrode 5
The electric field intensity generated in the insulating film 3 formed between the gate electrode 6 and the common electrode signal supply line 12 increases. As a result, a discharge occurs between the common electrode 56 and the first common electrode signal supply line 12, and the common electrode 56, the first common electrode signal supply line 12, and the insulating film 3 may be partially thermally damaged. Was.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a liquid crystal display device which can be manufactured with a high yield, in which dielectric breakdown due to discharge is suppressed in a manufacturing process. Aim.

[0013]

According to the liquid crystal display device of the present invention, a liquid crystal layer is sandwiched between a pair of substrates, and one of the pair of substrates is provided with a pixel electrode arranged in a matrix and the pixel electrode. A common electrode that is provided corresponding to each row of electrodes and that forms a storage capacitor in opposition to each of the pixel electrodes in each row, wherein the common electrode is electrically connected to the first common electrode signal supply line. A liquid crystal display device connected to the common electrode, wherein the common electrode is close to the first common electrode signal supply line when the common electrode and the first common electrode signal supply line are electrically separated from each other. The common electrode and the first electrode are arranged near the first end of the common electrode so as to suppress concentration of the charge amount at the first end.
It is characterized in that the common electrode signal supply line and the common electrode signal supply line overlap with an insulating film interposed therebetween. When the common electrode and the first common electrode signal supply line are electrically separated from each other, the vicinity of the first end of the common electrode is controlled so as to suppress concentration of the charge at the first end of the common electrode. Since the common electrode and the first common electrode signal supply line overlap with the insulating film interposed therebetween, it is possible to suppress the electric field intensity generated in the insulating film provided between the common electrode and the common electrode signal supply line. Accordingly, since no discharge occurs between the common electrode and the common electrode signal supply line, the insulating film, the common electrode and the common electrode signal supply line are not thermally damaged, and the liquid crystal display device can be manufactured with high yield. Is possible.

The common electrode further includes a second common electrode signal supply line formed in the same step as the common electrode;
If the second end of the common electrode has a comb shape connected to the second common electrode signal supply line, a potential signal can be supplied stably by the common electrode. Further, the common electrode and the second common electrode signal supply line can be easily manufactured.

[0015]

FIG. 1 shows a liquid crystal display 6 according to the present invention.
FIG. 9 shows an example of a plan view of an active matrix substrate 200 included in the active matrix substrate 00. FIG. 2 is a cross-sectional view taken along line AA ′ of FIG. A cross-sectional view taken along line CC ′ of FIG.
This is the same as FIG. 5 shown as a conventional example. Members having functions substantially similar to those of the conventional liquid crystal display device 700 are denoted by the same reference numerals, and detailed description thereof will be omitted. Note that the liquid crystal display device 600 of the present invention is driven similarly to the above-described conventional liquid crystal display device 700. In FIG. 1, for simplicity, a pixel electrode is a 2 × 2 pixel
Although shown as a matrix, the invention is not so limited. Hereinafter, the liquid crystal display device 600 of the present invention will be described with reference to FIGS.

As shown in FIG. 2, the liquid crystal display 60
0 denotes an active matrix substrate 20 which is a pair of substrates.
0 and a counter substrate 400, and a liquid crystal layer 300 sandwiched between these substrates.

As shown in FIG. 1, an active matrix substrate 200 has pixel electrodes 10 arranged in a matrix.
And a common electrode 11 facing the pixel electrode 10 to form a storage capacitor, and a first common electrode signal supply line 12 electrically connected to the common electrode 11 and the connection portion 13. The common electrode 11 is provided corresponding to each row of the pixel electrodes 10 and forms a storage capacitor in opposition to each pixel electrode 10 of each row. In particular, in the present invention, as shown in FIG. 2, near the first end 22 of the common electrode 11, the common electrode 11 and the first common electrode signal supply line 12 overlap with each other via the insulating film 3. ) Is different from the conventional example.

Hereinafter, an example of a method for manufacturing the liquid crystal display device 600 of the present invention will be briefly described with reference to FIG.

First, an Al / Ti thin film is deposited on the entire surface of the substrate 1 made of, for example, glass. In the photolithography process, after the resist coating, exposure, and development processes are performed on the Al / Ti thin film, dry etching is performed, and the scanning signal supply line 2 that also functions as the gate electrode 32 of the TFT and the second common electrode signal supply The line 8 and the common electrode 11 are formed (Step 102). In this step 102, the common electrode 11 is formed near its end 22 so as to overlap with the first common electrode signal supply line 12 formed in a later step 108. The common electrode 11 and the first
When the common electrode signal supply line 12 is electrically separated from the common electrode signal supply line 12 (a step before the step 112 in which the connection electrode 13 is formed), the concentration of the charge at the first end 22 of the common electrode 11 is reduced. As described above, the overlap width between the common electrode 11 and the first common electrode signal supply line 12 is appropriately determined. The common electrode 11 and the second common electrode signal supply line 8 are
2, the second end 24 of the common electrode 11 may be connected to the second common electrode signal supply line 8, and the common electrode 11 and the second common electrode signal supply line 8 may be formed in a comb shape ( (See FIG. 1). The scanning signal supply line 2, the second common electrode signal supply line 8, and the common electrode 11 are made of, for example, Ta, Mo, MoW, Cr, (Si, Cu, N
(including d, Zr and Ta).

Next, for example, SiN _{x is} applied to the entire surface of the substrate 1.
A thin film is deposited to form an insulating film 3 (Step 104, see FIGS. 2 and 5). The insulating film 3 can be formed of, for example, a mixture of SiN _x and SiO ₂ , AlO _x , and TaO _x other than SiN _x . Further, S on the insulating film 3
Deposit i-thin film. A photolithography step and an etching step (dry etching or wet etching) are performed to form the semiconductor layer 4 for forming the source, drain, and channel regions of the TFT 20 (Step 106, see FIG. 5).

Next, for example, an Al / Ti thin film is deposited,
A photolithography step and a dry etching step are performed to form the video signal supply line 5 and the source electrode 35, the drain electrode 9 and the first common electrode signal supply line 12 extending therefrom (step 108, FIG. 2 and 5). The video signal supply line 5 and the drain electrode 9
The first common electrode signal supply line 12 is made of, for example, Ta, Mo, MoW, Cr, an Al alloy (S
i, Cu, Nd, Zr, and Ta).

Further, for example, an SiNx thin film is deposited on the entire surface of the substrate to form an insulating film 6, and a photolithography process is performed.
Then, a dry etching step is performed to remove portions of the insulating film 6 corresponding to the contact holes 7, 70 and 72 (step 110, see FIGS. 2 and 5). The insulating film 6 can be formed of, for example, SiC ₂ , acrylic resin, polyimide, polyamide, or polycarbonate other than SiN _x .

On the insulating film 6, indium tin oxide (I
(TO) A thin film is deposited, and a photolithography step and a wet etching step are performed to form the pixel electrode 10 and the connection portion 13 (step 112). The pixel electrode 10 is connected to the drain electrode 9 of the TFT 20 through the contact hole 7.
(See FIG. 5). The connection part 13 connects the common electrode 11 and the first common electrode signal supply line 12 via the contact holes 70 and 72 (see FIG. 2). The active matrix substrate 200 is manufactured as described above.

Further, the counter substrate 4 is formed by a method known to those skilled in the art.
The liquid crystal display device 600 is completed by sandwiching the liquid crystal layer 300 between the active matrix substrate 200 and the counter substrate 400.

In the liquid crystal display device 600 manufactured by the above-described manufacturing method, the common electrode 11 is formed so as to overlap the first common electrode signal supply line 12 near the first end 22 thereof. The common electrode 11 and the first common electrode signal supply line 12 form a capacitive coupling structure using the insulating film 3 interposed therebetween as a dielectric. Therefore, when the first common electrode signal supply line 12 is formed (Step 1 in FIG. 6).
08), even if the substrate 1 is charged, the amount of charge hardly concentrates on the first end portion 22 of the common electrode 11, and the insulation provided between the common electrode 11 and the first common electrode signal supply line 12 is provided. Membrane 3
Is suppressed. Therefore, the common electrode 11
Since no discharge occurs between the first common electrode signal supply line 12 and the first common electrode signal supply line 12, the insulating film 3, the common electrode 11, and the first common electrode signal supply line 12 are not thermally damaged.

In this embodiment, the common electrode 11 has the second common electrode signal supply line 8 formed in the same step (step 102 in FIG. 6) (that is, in the same layer) to form a comb-shaped electrode. However, the shapes of the common electrode and the common electrode signal supply line for supplying a potential signal to the common electrode are not limited to this. For example, the potential signal may be supplied to the common electrode 11 only from the first common electrode signal supply line 12 without forming the second common electrode signal supply line 8. Also, the pixel electrode 1
The switching element connected to 0 is not limited to the TFT 20, but may be an MIM element, a varistor, or the like.

[0027]

As described above, according to the present invention, it is possible to provide a liquid crystal display device which can be manufactured with a high yield, in which dielectric breakdown due to electric discharge is suppressed in the manufacturing process.

[Brief description of the drawings]

FIG. 1 is a plan view illustrating an example of an active matrix substrate included in a liquid crystal display device of the present invention.

FIG. 2 is a cross-sectional view of the liquid crystal display device taken along line AA ′ of FIG.

FIG. 3 is a partial plan view of an active matrix substrate included in a conventional liquid crystal display device.

FIG. 4 is a cross-sectional view of the liquid crystal display device taken along the line BB ′ of FIG.

FIG. 5 is a cross-sectional view of the liquid crystal display device taken along the line CC ′ in FIGS. 1 and 3;

FIG. 6 is a diagram illustrating a method for manufacturing the liquid crystal display device of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 2 Scanning signal supply line 3 Insulating film 4 Semiconductor layer 5 Video signal supply line 6 Insulating film 7, 70, 72 Contact hole 8 First common electrode signal supply line 9 Drain electrode 10 Pixel electrode 11, 56 Common electrode 12 Second Common electrode signal supply line 13 Connection part 20 TFT 22 First end 24 Second end 32 Gate electrode 35 Source electrode 100, 200 Active matrix substrate 300 Liquid crystal layer 400 Opposite substrate 600, 700 Liquid crystal display device

Continuation of the front page F term (reference) 2H092 GA14 JB24 JB32 JB33 JB56 JB64 JB79 KB04 KB25 NA14 5C094 AA42 BA03 BA43 CA19 EA04 EA07 FB15 GB10

Claims (2)

[Claims] 1. A liquid crystal layer is sandwiched between a pair of substrates. One of the pair of substrates is provided so as to correspond to pixel electrodes arranged in a matrix and each row of the pixel electrodes. A common electrode facing each of the pixel electrodes to form a storage capacitor, wherein the common electrode is electrically connected to a first common electrode signal supply line, When the common electrode and the first common electrode signal supply line are electrically separated from each other, the charge amount concentration at the first end of the common electrode close to the first common electrode signal supply line is suppressed. As described above, the liquid crystal display device in which the common electrode and the first common electrode signal supply line overlap with each other near the first end of the common electrode via an insulating film. 2. The common electrode further includes a second common electrode signal supply line formed in the same step as the common electrode, and a second end of the common electrode is connected to the second common electrode signal supply line. 3. The liquid crystal display device according to claim 2, wherein said liquid crystal display device has a comb shape.