JPH06148616A - Liquid crystal display panel - Google Patents

Abstract

PURPOSE:To provide protective film capable of satisfying both a high dielectric constant and high insulation, to remarkably improve a display grade as a result, and to provide a liquid crystal display panel capable of increasing yield. CONSTITUTION:In the liquid crystal display panel in which an insulating substrate 1 made of transparent glass on the surface of which a gate electrode 7 of TFT 21, a source electrode 10, a drain electrode 11, and a pixel electrode 12, etc., are formed is adhered with a glass substrate 15 on the counter plane side of which a counter electrode 17, etc., is formed, and a liquid crystal molecule 19 is injected between the substrates 1, 15, the protective film 13a of dielectric constant>10 is formed by a CVD method or sputtering method, etc., by using tantalum pentoxide with high dielectric constant and material characteristic with high insulating property, etc., extending over the entire plane of the insulating substrate 1 so as to cover elements formed on the insulating substrate 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display panel in which electrode wirings are formed on opposing surfaces, at least one of which has translucency, and a liquid crystal layer is sealed between a pair of substrates which are bonded to each other. In particular, the present invention relates to a liquid crystal display panel capable of improving display quality and yield.

[0002]

2. Description of the Related Art As an example of a liquid crystal display panel, there is an active matrix drive system in which display pixels arranged in a matrix are selectively driven by a switching element to form a display pattern. As this switching element, a thin-film-transistor (hereinafter referred to as TFT) element, an MIM (metal-insulating film-metal) element, a MOS transistor element, a diode, a varistor, etc. are generally used. With such a switching element, by switching the voltage signal applied between the pixel electrode and the counter electrode facing it,
The optical modulation of liquid crystal as a display medium interposed therebetween is visually recognized as a display pattern.

FIG. 3 shows an active matrix substrate which is a component of such a liquid crystal display panel. In this active matrix substrate, for example, a plurality of scanning lines 2, 2, ... And a plurality of signal lines 3, 3 ,. I am doing it.
The pixel electrodes 12 for driving the liquid crystal are provided in respective regions surrounded by the adjacent scanning lines 2, 2 ... And the signal lines 3, 3.
And a switching element 21 for selectively driving the pixel electrode 12. The switching element 21 is connected to the scanning line 2, the signal line 3 and the pixel electrode 12, respectively.

A scanning line driving circuit 22 drives the scanning lines 2, and a signal line driving circuit 23 drives the signal lines.

Next, a TFT is used as the switching element 21.
A cross-sectional structure of an active matrix drive type liquid crystal display panel using is described with reference to FIG.

A scanning line 2 having a gate electrode 7 is formed on an insulating substrate 1, and an oxide insulating film 4 is provided so as to cover the scanning line 2. As the material of the scanning line 2, a metal such as tantalum or aluminum is used so that the oxide insulating film 4 provided thereon can be formed well.

A gate insulating film 5 is provided on the entire surface of the insulating substrate 1 so as to cover the oxide insulating film 4. A semiconductor layer 6 made of a silicon thin film is formed on the gate insulating film 5 so as to cover the gate electrode 7. An etching stopper layer 8 is provided in the center of the semiconductor layer 6. A pair of contact layers 9 a and 9 b are formed on both ends of the etching stopper layer 8 so as to be in contact with both ends of the semiconductor layer 6.

A source electrode 10 branched from the signal line 3 is patterned on one contact layer 9a, and a drain electrode 11 is patterned on the other contact layer 9b. At one end of the drain electrode 11,
A pixel electrode 12 made of a transparent conductive film such as ITO is connected and formed. The end of the pixel electrode 12 is the drain electrode 1
Riding on one end of 1.

The above-mentioned gate electrode 7, source electrode 10,
The TFT 21 is formed by the drain electrode 11 and the like. Also,
The TFT 21 and the pixel electrode 12 are formed on the entire surface of the insulating substrate 1.
The protective film 13b and the alignment film 14 are laminated in this order so as to cover the. Silicon nitride is used as the material of the protective film 13b. Polyimide is used as the material of the alignment film 14. Reference numeral 20 is a base coat insulating film provided as needed.

Insulating substrate 1 having picture element electrodes 12 and the like formed thereon
A color filter 16, a counter electrode 17, and an alignment film 18 are laminated in this order on the facing surface side of the other glass substrate 15 facing the other side. A black matrix (not shown) is formed around the color filter 16 as needed.

Liquid crystal molecules 19 are enclosed as a display medium between the insulating substrate 1 and the glass substrate 15. The liquid crystal molecules 19 undergo orientation conversion in response to an applied voltage between the pixel electrode 12 and the counter electrode 17, and this optical modulation is visually recognized as a display pattern.

[0012]

When the liquid crystal display panel having the above structure is used in a liquid crystal display device, since silicon nitride having a low dielectric constant is used as the material of the protective film 13b, the pixel electrode 12 and When a voltage is applied between the counter electrode 17 and the liquid crystal molecule 19 to drive the liquid crystal molecule 19,
However, there is a problem that the display quality is degraded because the voltage is not sufficiently applied.

As a technique for solving such a problem, it is considered that polyimide or the like used as the alignment film 14 has a high dielectric constant and is used as the protective film 13b. However, in this case, the insulating property required as the protective film cannot be sufficiently obtained, and there is a new problem that current leakage easily occurs and the yield is reduced.

The present invention solves the problems of the prior art as described above, and it is possible to realize a protective film satisfying both a high dielectric constant and a high insulating property, and as a result, the display quality can be remarkably improved, and An object of the present invention is to provide a liquid crystal display panel that can improve the yield.

[0015]

A liquid crystal display panel according to the present invention has a liquid crystal layer between a pair of substrates in which electrode wirings are formed on opposing surfaces, at least one of which has translucency, and which are bonded to each other. In a liquid crystal display panel in which is enclosed, at least between the liquid crystal layer and one of the electrode wirings,
The insulating protective film containing a high-dielectric material having a relative dielectric constant of 10 or more is formed, whereby the above object is achieved.

[0016]

When the insulating protective film containing a high dielectric material having a relative dielectric constant of 10 or more is provided between the liquid crystal layer and one of the electrode wirings, a voltage is applied between the electrode wirings. When the liquid crystal is driven by the liquid crystal, a sufficient voltage can be applied to the liquid crystal.

[0017]

EXAMPLES Examples of the present invention will be described below.

Example 1 FIG. 1 shows Example 1 of the liquid crystal display panel of the present invention. This liquid crystal display panel uses TFTs as switching elements. The configuration will be described in detail below.

A scanning line 2 having a gate electrode 7 is formed on an insulating substrate 1 made of transparent glass, and an oxide insulating film 4 is provided so as to cover the scanning line 2. As the material of the scanning line 2, a metal such as tantalum or aluminum is used so that the oxide insulating film 4 provided thereon can be formed well.

A gate insulating film 5 is provided over the entire surface of the insulating substrate 1 so as to cover the oxide insulating film 4. A semiconductor layer 6 made of a silicon thin film is formed on the gate insulating film 5 so as to cover the gate electrode 7. An etching stopper layer 8 is provided in the center of the semiconductor layer 6. A pair of contact layers 9 a and 9 b are formed on both ends of the etching stopper layer 8 so as to be in contact with both ends of the semiconductor layer 6.

A source electrode 10 branched from the signal line 3 is patterned on one contact layer 9a, and a drain electrode 11 is patterned on the other contact layer 9b. At one end of the drain electrode 11,
A pixel electrode 12 made of a transparent conductive film such as ITO is connected and formed. The end of the pixel electrode 12 is the drain electrode 1
Riding on one end of 1.

The above-mentioned gate electrode 7, source electrode 10,
The TFT 21 is formed by the drain electrode 11 and the like. Also,
The TFT 21 and the pixel electrode 12 are formed on the entire surface of the insulating substrate 1.
The protective film 13a and the alignment film 14 are laminated in this order so as to cover the. Polyimide is used as the material of the alignment film 14. Further, the protective film 13a is formed of the material described later. Reference numeral 20 is a base coat insulating film provided as needed.

Insulating substrate 1 having picture element electrodes 12 and the like formed thereon
A color filter 16, a counter electrode 17, and an alignment film 18 are laminated in this order on the facing surface side of the other glass substrate 15 facing the other side. A black matrix (not shown) is formed around the color filter 16 as needed.

Liquid crystal molecules 19 are enclosed as a display medium between the insulating substrate 1 and the glass substrate 15. The liquid crystal molecules 19 undergo orientation conversion in response to an applied voltage between the pixel electrode 12 and the counter electrode 17, and this optical modulation is visually recognized as a display pattern.

TF constituting such a liquid crystal display panel
The T-side substrate is manufactured by the following process. First, 300 tantalum is deposited on the insulating substrate 1 by a sputtering method.
A film having a thickness of nm is formed, and then the scanning line 2 having the gate electrode 7 is patterned by a photolithography technique.

Next, a base coat insulating film 20 made of tantalum pentoxide, silicon nitride, silicon oxide, or the like is laminated between the scanning line 2 and the insulating substrate 1 by a sputtering method, a CVD method, or the like. This base coat insulating film 20
Are formed as needed. Next, an oxide insulating film 4 having a thickness of 300 nm is formed on the scanning line 2 having the gate electrode 7 by an anodic oxidation method or a thermal oxidation method. In this example, the anodic oxidation method was used.

Next, the scanning line 2 is formed by the plasma CVD method.
Then, silicon nitride is laminated over the entire surface of the insulating substrate 1 so as to cover the oxide insulating film 4 to form a gate insulating film 5 having a thickness of 300 nm. As described above, when the gate insulating film 5 is superposed on the oxide insulating film 4 and the insulating film has a multilayer structure, there is an advantage that the insulating property can be improved. Then, on the gate insulating film 5, amorphous silicon is laminated with a thickness of 30 nm by the plasma CVD method to form the semiconductor layer 6.

Next, silicon nitride 20 is formed on the semiconductor layer 6.
The layers are stacked with a thickness of 0 nm, and then the etching stopper layer 8 is patterned by a photolithography technique. Subsequently, layers of n ⁺ type amorphous silicon to which phosphorus is added, which will be contact layers 9a and 9b later, are stacked with a thickness of 50 nm by a plasma CVD method. Then, the contact layers 9a and 9b are pattern-formed with the semiconductor layer 6 laminated previously by the method of photolithography.

Next, on top of that, Ti is formed by a sputtering method.
After forming a film, the Ti film is patterned by a photolithography method to form the signal line 3, the source electrode 10 and the drain electrode 11 of the TFT 21. As the material of the signal line 3, the source electrode 10 and the drain electrode 11, other metals such as Al, Cr and Mo can be used in addition to Ti.

Next, a transparent conductive film containing indium oxide as a main component is formed to a thickness of 80 nm on the patterned Ti film, and then the pixel electrode 12 and this pixel electrode are formed by a photolithography technique. An additional capacitor (not shown) branched from 12 is patterned.

Next, tantalum pentoxide or the like having a high dielectric constant and high insulating material characteristics is used over the entire surface of the insulating substrate 1 so as to cover the elements formed by the above procedure, The protective film 13a is formed by the CVD method, the sputtering method, or the like. Here, the relative permittivity of the protective film 13a is preferably 10 or more.

Next, the alignment film 14 is formed on the protective film 13a, and the TFT side substrate is manufactured.

The TFT manufactured in this way
The side substrate, and the color filter 16 and the counter electrode 1 on the counter surface side
7 and the alignment film 18 are laminated in this order on the glass substrate 15, that is, on the opposite side substrate, and the liquid crystal molecules 19 are sealed between the two to manufacture the liquid crystal display panel of the present invention. Since the manufacturing process of the opposite substrate is performed by a known process, a detailed description thereof will be omitted.

According to such a liquid crystal display panel, since the protective film 13a is formed of a material such as tantalum pentoxide having a high dielectric constant and a high insulating property, it faces the pixel electrode 12. A sufficient voltage can be applied to the liquid crystal molecules 19 when a voltage is applied between the electrodes 17 and the liquid crystal molecules 19 are driven. Therefore, the display quality does not deteriorate. Further, since sufficient insulation is secured, current leakage does not occur and the yield can be improved.

Example 2 FIG. 2 shows Example 2 of the liquid crystal display panel of the present invention. The second embodiment differs from the first embodiment in that the protective film 13a is provided on the counter substrate side. That is, as shown in the figure, a protective film 13a made of the same material as described above is formed on the opposing surface side of the glass substrate 15 and between the opposing electrode 17 and the alignment film 18.

Also in the case of the second embodiment, the display quality and the yield can be improved as in the first embodiment.

The protective film 13a as described above is formed of TF.
It may be provided on both the T-side substrate and the counter-side substrate.

In each of the above embodiments, the transparent glass is used for both the TFT side substrate and the counter side substrate, but other transparent materials can be used. When a transparent material is used as the material for both substrates in this way, a transmissive liquid crystal display panel can be realized. When a non-transparent material is used for one of the substrates, a reflective liquid crystal display panel can be realized.

Further, in each of the above embodiments, the case where the present invention is applied to the liquid crystal display panel of the active matrix drive system using the TFT as the switching element has been described, but the MIM element, the MOS transistor element, the diode, the varistor, etc. The present invention can be similarly applied to a liquid crystal display panel using another switching element.

[0040]

As described above, the liquid crystal display panel of the present invention is
Since an insulating protective film containing a highly dielectric material having a relative dielectric constant of 10 or more is provided between the liquid crystal layer and one of the electrode wirings, a voltage is applied between both electrode wirings to drive the liquid crystal. In that case, a sufficient voltage can be applied to the liquid crystal.
Therefore, the display quality can be improved. Moreover, since sufficient insulation is secured, current leakage does not occur, and defective products due to this do not occur. Therefore, the yield can be improved.

[Brief description of drawings]

FIG. 1 is a partial sectional view showing a first embodiment of a liquid crystal display panel of the present invention.

FIG. 2 is a partial cross-sectional view showing a second embodiment of the liquid crystal display panel of the present invention.

FIG. 3 is a plan view schematically showing an active matrix substrate.

FIG. 4 is a partial cross-sectional view showing a conventional example of a liquid crystal display panel.

[Explanation of symbols]

 1 Insulating Substrate 2 Scan Line 3 Signal Line 4 Oxide Insulating Film 5 Gate Insulating Film 6 Semiconductor Layer 7 Gate Electrode 8 Etching Stopper Layer 9a, 9b Contact Layer 10 Source Electrode 11 Drain Electrode 12 Pixel Electrode 13a High Dielectric Insulation Protective film 13b Insulating protective film 14 Alignment film 15 Glass substrate 16 Color filter 17 Counter electrode 18 Alignment film 19 Liquid crystal molecule 20 Base coat insulation film 21 TFT (Switching element) 22 Scan line drive circuit 23 Signal line drive circuit 23

 ─────────────────────────────────────────────────── ─── Continued front page (72) Inventor Takayoshi Nagayasu 22-22 Nagaike-cho, Abeno-ku, Osaka-shi, Osaka Within Sharp Corporation (72) Inventor Mikio Katayama 22-22 Nagaike-cho, Abeno-ku, Osaka, Osaka Incorporated (72) Inventor Shigemitsu Mizushima 22-22 Nagaike-cho, Abeno-ku, Osaka-shi, Osaka

Claims (1)

[Claims] 1. A liquid crystal display panel in which electrode wirings are formed on opposing surfaces, at least one of which has a light-transmitting property, and a liquid crystal layer is enclosed between a pair of substrates which are bonded to each other. A liquid crystal display panel in which an insulating protective film containing a high-dielectric material having a relative dielectric constant of 10 or more is formed between and one of the electrode wirings.