JPH0444014A - Active matrix type liquid crystal display device - Google Patents

Abstract

PURPOSE:To suppress the generation of a pixel display defect and to improve the manufacture yield by shaping the auxiliary storage capacity formation part of a transparent pixel electrode or a pixel storage capacity electrode without overlapping with an end part of an auxiliary storage capacity formation electrode or gate line electrode wiring pattern, and providing semiconductor layers below a connection part. CONSTITUTION:The auxiliary storage capacity C formation part of the transparent pixel electrode 18 or the pixel storage capacity electrode 18a connected to the transparent pixel electrode 18 is shaped without overlapping with the end part of the auxiliary storage capacity formation electrode 15 or gate line electrode wiring pattern except at the connection part 18b for the transparent pixel electrode 18. Then the overlapping part between the transparent pixel electrode 18 and auxiliary storage capacity formation electrode pattern end part 15a which is the main cause of a pixel display defect is made extremely short. Further, the semiconductor layers 17a and 17b are provided below the connection part 18b when a non-metal layer, e.g. thin film transistor (TFT) is manufactured to perform insulation and reinforcement, thereby obtaining structure which has substantially no overlapping part. Consequently, the generation of the pixel display defect can be suppressed without altering the manufacture process and the manufacture yield is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to an active matrix liquid crystal display device using thin film transistors as switching elements.

(Prior Art) Liquid crystal display devices are used for television displays, graphic displays, etc., and active matrix type liquid crystal display devices with large capacity and high definition are being actively developed and put into practical use. In this type of liquid crystal display device, semiconductor switches are used as means for driving and controlling each pixel so that high contrast display without crosstalk can be performed. As this semiconductor switch, thin film transistors (hereinafter referred to as TPTs) are often used because they are capable of transmissive display and can easily be made to have a large area.

FIG. 3 is a cross-sectional view of a conventional active matrix liquid crystal display device using the above-mentioned TPT array, and shows a cross section corresponding to the section ■-■ in FIG. FIG. 3 is a plan view of a part of the substrate.

]] is a first substrate, and this first substrate 1] has a gate line 13 on an insulating substrate 12 made of, for example, transparent glass, a gate electrode 14 integrated with the gate line 13, and a gate electrode 14 for forming an auxiliary storage capacitor. An electrode (hereinafter referred to as a capacitor electrode) 15 is formed, and an insulating film 16 is formed to cover the gate line] 3, the gate electrode 14, and the capacitor electrode 15.

Furthermore, a semiconductor layer 17 made of, for example, amorphous silicon is formed at a predetermined position on the insulating film 16, and a portion 18a is formed at another predetermined position on the insulating film 16 so as to overlap with the capacitor electrode 15. A transparent pixel electrode 18 is formed.

Also, on the insulating film 16, a data line 19 made of aluminum, for example, intersects with the gate line 13 and the capacitor electrode 5; A source electrode 21 made of aluminum, for example, facing the drain electrode 20 and connecting the semiconductor layer 17 and the transparent pixel electrode 18.
or is formed.

An insulating protective film 22 is formed at a predetermined position on the insulating substrate 12 on which each element is arranged as described above, and a liquid crystal alignment film 23 is further formed over the entire area of the upper surface.

In this way, a first substrate]] is formed, and a thin film transistor (hereinafter referred to as TFT) 24 consisting of a gate electrode 14, a semiconductor layer 17, a drain electrode 20, and a source electrode 21 is formed on this first substrate 11. is formed.

On the other hand, the second substrate 3] has a transparent counter electrode 33 and a liquid crystal alignment film 34 formed in this order on an insulating substrate 32 made of, for example, glass. and the first substrate]] and the second substrate.
The peripheral portion is sealed to the substrate 31 with a gap of about 6 μm, and a liquid crystal 41 is sealed and sandwiched within this gap.

FIG. 5 shows an equivalent circuit of the liquid crystal display device. That is, a TPT 24 is arranged at each intersection between a plurality of parallel gate lines] 3 and a plurality of parallel gate lines 9 perpendicular thereto, and each gate electrode 14 of the TPT 24 is arranged row by row. While being connected to the gate line 13,
Each drain electrode 20 is connected to a data line 19 for each column,
Each source electrode 21 is connected to each transparent pixel electrode 18, and a liquid crystal 41 is sandwiched between the transparent pixel electrode]8 and the transparent counter electrode 33.

An auxiliary storage capacitor C is formed by sandwiching an insulating film 16 between each transparent pixel electrode 18 and the capacitor electrode 5 facing thereto.

Further, each capacitor electrode] 5 is either grounded as shown in FIG. 5 or connected to the transparent counter electrode 33, so that all pixels have the same potential.

Then, the gate lines] 3 are sequentially scanned and driven by the address signal, and the TPTs 24 are sequentially turned on row by row. On the other hand, in synchronization with the scanning of the gate line 13, the data line 19
Pixel signals are supplied in parallel to the selected number sequence. As a result, the signal voltage is sequentially guided to the transparent pixel electrode 18 row by row, and the liquid crystal 41 sandwiched between the transparent counter electrode 33 is excited and becomes an image signal to display an image.

(Problems to be Solved by the Invention) The active matrix liquid crystal display device as described above is
When the address signal voltage applied to the gate line 1-3 falls, a level shift of the pixel potential occurs due to capacitive coupling of the device. This level shift affects the display quality (
For example, from the viewpoint of flicker) and reliability of the liquid crystal material, it is desirable to have a smaller value, and for this reason, an auxiliary storage capacitor C is required.

However, in the conventional active matrix liquid crystal display device as described above, many dielectric breakdowns of the auxiliary storage capacitor C (dielectric breakdown between the capacitor electrode 15 and the transparent pixel electrode 18) occur, and these problems significantly affect the display. There are many point defects that impair the quality.

The main location where this dielectric breakdown occurs is a region 15a where the transparent pixel electrode 18 overlaps the pattern end of the capacitor electrode 15, as shown in FIGS. 3 and 4. this is,
This is due to the fact that the insulating film 16 corresponds to the above-mentioned portion 15a, in terms of both its shape and film quality, and that it has poor electrical withstand voltage and is subject to process damage during pattern formation, among which etching process damage is an extremely serious problem. Improving yield is becoming difficult.

The present invention has been made in response to such conventional circumstances, and an object of the present invention is to provide an active matrix liquid crystal display device that can easily improve the yield without increasing the number of manufacturing steps. do.

[Structure of the Invention] (Means for Solving the Problems) The present invention has a semiconductor layer between a drain electrode and a source electrode at each intersection between a plurality of gate lines and a plurality of data lines crossing the gate lines. A thin film transistor is arranged, a transparent pixel electrode is connected to the source electrode, and an electrode for forming an auxiliary storage capacitor crossing the data line or the gate line is connected to the transparent pixel electrode or at least the transparent pixel electrode. a first substrate on which an auxiliary storage capacitor is formed by laminating a pixel storage capacitor electrode with an insulating film interposed therebetween; a second substrate on which a transparent counter electrode is formed;
and a liquid crystal sandwiched between second substrates, wherein the pixel storage capacitor electrode or the auxiliary storage capacitor forming portion of the transparent pixel electrode connects to the transparent pixel electrode. is formed without being overlapped with an end of the auxiliary storage capacitor forming electrode pattern or the gate line pattern, and the connecting portion,
In addition to the insulating film, a non-metal layer is interposed in the overlapping portion with the end portion of the auxiliary storage capacitor forming electrode pattern or the gate line pattern.

(Function) In the active matrix liquid crystal display device of the present invention, the auxiliary storage capacitor forming portion of the transparent pixel electrode or the pixel storage capacitor electrode connected to the transparent pixel electrode is removed from the transparent pixel electrode except for the connection portion with the transparent pixel electrode. , the shape is such that it does not overlap with the end of the auxiliary storage capacitor forming electrode or the gate line electrode wiring pattern, and the overlapping portion of the transparent pixel electrode and the end of the auxiliary storage capacitor forming electrode pattern, which is the main cause of pixel display defects as described above, is Keep it extremely short. At the same time, by providing a non-metal layer, for example, a semiconductor layer during TPT manufacturing, under the connection portion, the insulation is reinforced and a structure is created in which there is substantially no overlapping portion.

As a result, without changing the manufacturing process, it is possible to create a structure that does not cause process damage, especially related to the overlapping portion, suppressing the occurrence of pixel display defects, improving display quality, and improving manufacturing yield. be able to.

(Example) An example of the present invention will be described below with reference to FIGS. 1 and 2. Figure 1 is a sectional view of an active matrix liquid crystal display device, showing a cross section corresponding to section I-1 in Figure 2, and Figure 2 is a plan view of a part of the first substrate in Figure 1. be.

This device basically has the same configuration as the device shown in FIGS. 3, 4, and 5, and corresponding parts will be described with the same reference numerals and according to the manufacturing process. .

First, the first substrate 11 is formed by depositing molybdenum to a thickness of 150 nm by sputtering on an insulating substrate 12 made of, for example, transparent glass, and then forming a gate line 13, a gate electrode 14 integrated with the gate line 13, and an auxiliary storage capacitor. A forming electrode (hereinafter referred to as a capacitor electrode) 15 is patterned. This electrode 15 is functionally the same whether it is a transparent electrode or an opaque electrode.

Next, an insulating film 6 made of silicon dioxide, for example, is deposited to a thickness of 300 nm on the insulating substrate 12 by plasma CVD or the like so as to cover the gate wire 13, the gate electrode 4, and the capacitor electrode 15. Furthermore, a semiconductor layer is patterned by depositing, for example, amorphous silicon to a thickness of 300 nm at a predetermined position on this insulating film 16 by plasma CVD. At this time, in addition to the thin film transistor forming portion 17a, a portion 17 corresponding to a connecting portion 18b between a transparent pixel electrode 18 and a pixel storage capacitor electrode 18a, which will be described later, is added.
A pattern is also formed on b.

Next, for example, ITO is applied to another predetermined position on the upper insulating film]6.
is deposited to a thickness of 50 nm by sputtering or the like to form the transparent pixel electrode 18. At this time, the transparent pixel electrode 18 is arranged such that a part (pixel storage capacitor electrode) 18a overlaps the capacitor electrode 15, and at a position relative to the wiring pattern end 15a of the capacitor electrode 15, the transparent pixel electrode 18 is placed on the semiconductor layer 17b. Connecting part], 8
Leaving b, transparent pixel "electrode] 8 or gap 18c
] 1.

Further, on the upper insulating film 16, a data line 19 made of aluminum, for example, intersects with the gate line]3 and the capacitor electrode 15, and integrally with the data line]9, the semiconductor layer 1
A drain electrode 20 is formed on one side of -7, and a source electrode 21 made of aluminum, for example, is formed to face the drain electrode 20 and connect the other side of the semiconductor layer 17 to the transparent pixel electrode 18.

Next, after applying an insulating protective film 22 made of polyimide to a thickness of 1 μm over the entire surface of the insulating substrate 12 on which each element is arranged as described above, polyimide is coated on the upper surface of the transparent pixel electrode 18 at a predetermined position. Then, a liquid crystal alignment film 23 made of polyimide is applied to the entire upper surface area.

In this way, while forming the first substrate 11,
Gate electrode]4, semiconductor layer]7a on this first substrate 11
1. A thin film transistor 24 consisting of a drain electrode 20 and a source electrode 21 is formed.

On the other hand, for the second substrate 31, a transparent counter electrode 33 made of ITO and a liquid crystal alignment film 34 having a thickness of 100 nIIl are sequentially formed on an insulating substrate 32 made of glass, for example. Then, the first substrate 11 and the second substrate 31 are sealed at their peripheries with a gap of about 6 μm maintained, and the liquid crystal 4 is sealed and sandwiched in this gap.

In this way, as shown in FIG. 5, a TPT 24 is placed at each intersection between a plurality of parallel game i lines 13 and a plurality of data lines orthogonal to each other and parallel to each other, The gate electrode] 4 of this TPT 24 is connected to the gate line 13,
An auxiliary storage capacitor C is formed by connecting the drain electrode 20 to the pig wire 19 and the source electrode 21 to the transparent pixel electrode 18, and sandwiching the insulating film 16 between the pixel storage capacitor electrode 18a and the capacitor electrode 15 opposite thereto. do.

In this embodiment with the above configuration, the transparent pixel electrode 18 has a gap 18c in the overlapped portion with the wiring pattern end 15a of the capacitor electrode 15, so that the wiring between the transparent pixel electrode 18 and the capacitor electrode 15 is Pattern end 15
The semiconductor layer 17b is formed in the overlapped portion between the connecting portion 18b between the transparent pixel electrode 18 and the pixel storage capacitor electrode 1.8a and the wiring pattern end portion 15a of the capacitor electrode 15. Due to the presence of the transparent pixel electrode 18, there is virtually no electrode on the pattern end 15a that has the same potential as the transparent pixel electrode 18.

That is, the presence of the semiconductor layer 17b allows manufacturing without causing process damage to the insulating film 16 in the relevant portion, and eliminates the main cause of pixel defects.

[Effects of the Invention] As explained above, in the present invention, the auxiliary storage capacitor forming portion of the transparent pixel electrode or the pixel storage capacitor electrode connected to the transparent pixel electrode is removed, excluding the connecting portion with the transparent pixel electrode. ,
The shape is such that it does not overlap with the edge of the auxiliary storage capacitor forming electrode or the gate line electrode wiring pattern, and the overlap between the transparent pixel electrode and the edge of the auxiliary storage capacitor forming electrode pattern, which is the main cause of pixel display defects as described above, is minimized. shorten. At the same time, by providing a non-metal layer, for example, a semiconductor layer during TFT manufacturing, under the above-mentioned connection part, the insulation is reinforced, and the
The structure shall be such that there is no double layer overlap.

As a result, without changing the manufacturing process, it is possible to create a structure that does not cause process damage, especially related to the overlapping portion, suppressing the occurrence of pixel display defects, improving display quality, and improving manufacturing yield. can be made to

[Brief explanation of the drawing]

FIG. 1 is a sectional view taken along the line I-1 in FIG. 2 showing an embodiment of the active matrix liquid crystal display device of the present invention, FIG. 2 is a plan view showing a part of FIG. 1, and FIG. 3 is a conventional FIG. 4 is a cross-sectional view of the section ■-■ showing the active matrix type liquid crystal display device of FIG. 4, FIG. 4 is a plan view showing a part of FIG. 3, and FIG. FIG. 11......First board 13...
. . . Kate wire] 5 . . . Electrodes for forming auxiliary storage capacitor 16 . . . Insulating films 17a, b . . . Semiconductor Layer 18......Transparent pixel electrode 18a...
...Pixel storage capacitor electrode 18b...
・Connection section] 8C...Gap section 19...Data line 20...Drain electrode 21...
...... Source electrode 24 ......
・・・Thin film transistor 31・・・・・・・・・・・・
Second substrate 33...Transparent counter electrode 41...Liquid crystal C...Auxiliary storage capacity applicant
Toshiba Corporation

Claims (1)

[Claims] (1) A thin film transistor having a semiconductor layer between a drain electrode and a source electrode is arranged at each intersection of a plurality of gate lines and a plurality of data lines intersecting with the gate lines, and a transparent pixel electrode is connected to the source electrode. , and an electrode for forming an auxiliary storage capacitor that intersects with the data line or the gate line and the transparent pixel electrode or at least a pixel storage capacitor electrode connected to the transparent pixel electrode are connected via an insulating film. An active matrix liquid crystal comprising: a first substrate formed with a laminated auxiliary storage capacitor, a second substrate formed with a transparent counter electrode, and a liquid crystal sandwiched between the first and second substrates. In the display device, an auxiliary storage capacitor forming portion of the pixel storage capacitor electrode or the transparent pixel electrode, except for a connection portion with the transparent pixel electrode,
is formed without overlapping an end of the auxiliary storage capacitor forming electrode pattern or the gate line pattern, and is formed in an overlapping portion of the connection portion and the end of the auxiliary storage capacitor forming electrode pattern or the gate line pattern. . An active matrix liquid crystal display device, characterized in that a nonmetallic layer is interposed in addition to the insulating film.