JPH06202108A - Liquid crystal display device - Google Patents
Liquid crystal display deviceInfo
- Publication number
- JPH06202108A JPH06202108A JP28147692A JP28147692A JPH06202108A JP H06202108 A JPH06202108 A JP H06202108A JP 28147692 A JP28147692 A JP 28147692A JP 28147692 A JP28147692 A JP 28147692A JP H06202108 A JPH06202108 A JP H06202108A
- Authority
- JP
- Japan
- Prior art keywords
- tft
- gate electrode
- electrode
- liquid crystal
- crystal display
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Landscapes
- Liquid Crystal (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は、薄膜トランジスタ（Ｔ
ＦＴ：Ｔｈｉｎ Ｆｉｌｍ Ｔｒａｎｓｉｓｔｏｒ）を
スイッチング素子として液晶を駆動する液晶表示装置に
関するものである。The present invention relates to a thin film transistor (T
The present invention relates to a liquid crystal display device that drives a liquid crystal using a FT (Thin Film Transistor) as a switching element.
【０００２】[0002]
【従来の技術】図３に従来の構成の液晶表示装置のＴＦ
Ｔの断面図を示す。2. Description of the Related Art FIG. 3 shows a TF of a liquid crystal display device having a conventional structure.
A sectional view of T is shown.
【０００３】図に示すように絶縁基板１上に金属からな
るゲート電極２と、このゲート電極２上にゲート絶縁層
３と、このゲート絶縁層３上に非晶質シリコンを主成分
とする半導体４と、その上部にソース電極５、およびド
レイン電極６が形成され、逆スタガ型ＴＦＴが構成され
ている。As shown in the figure, a gate electrode 2 made of metal is formed on an insulating substrate 1, a gate insulating layer 3 is formed on the gate electrode 2, and a semiconductor containing amorphous silicon as a main component is formed on the gate insulating layer 3. 4, and the source electrode 5 and the drain electrode 6 are formed on the upper part of the electrode 4, thereby forming an inverted stagger type TFT.
【０００４】またＴＦＴ上には、有機材料を主成分とす
る絶縁層からなる配向膜７が、ＴＦＴと界面を接してＴ
ＦＴ全面に形成されている。配向膜材料としては、例え
ば、ポリイミド、ポリビニルアルコール、カルボン酸、
１塩基性カルボン酸Ｃｒ錯体、２塩基性カルボン酸Ｃｒ
錯体、ヘキサデシルトリメチルアンモニウムブロマイ
ド、オクタデシルアミンハイドロクロライド、ポリオキ
シエチレン、ヘキサメチルジシロキ酸、パーフルオロジ
メチルシクロヘキサン、テトラフルオロエチレン、有機
シラン等がある。On the TFT, an alignment film 7 made of an insulating layer containing an organic material as a main component is in contact with the TFT at the interface,
It is formed on the entire surface of the FT. As the alignment film material, for example, polyimide, polyvinyl alcohol, carboxylic acid,
Monobasic carboxylic acid Cr complex, dibasic carboxylic acid Cr
Complexes, hexadecyltrimethylammonium bromide, octadecylamine hydrochloride, polyoxyethylene, hexamethyldisiloxic acid, perfluorodimethylcyclohexane, tetrafluoroethylene, organic silanes and the like.
【０００５】[0005]
【発明が解決しようとする課題】しかしながらかかる構
成の液晶表示装置では、配向膜７がＴＦＴの上部全面に
形成されているため、ゲート電極２の直上部の配向膜７
が、ゲート電極２のオフ時間の間に界面分極を起こす。
これは液晶表示装置の実動作時間において、ＴＦＴが選
択されるごく短いオン期間、すなわちゲートが正となる
期間を除いて、ほとんどの期間ＴＦＴのゲートにはオフ
信号すなわち、負の電圧が印加され、このゲートの負の
バイアスがＴＦＴのバックサーフェスに形成され配向膜
７の界面分極を引き起こすというものである。そしてこ
の界面分極により半導体４にエレクトロンが誘起され、
ゲートのオフ時にもかかわらずソース電極５とドレイン
電極６の間に電流経路が生じ、ＴＦＴのオフ特性の劣化
が起こる。配向膜中の分極成分としては、配向膜形成反
応時の中間生成物や反応前駆体、不純物イオンが考えら
れ、これは有機材料を主成分とする絶縁材料に特有の現
象である。However, in the liquid crystal display device having such a structure, since the alignment film 7 is formed on the entire upper surface of the TFT, the alignment film 7 immediately above the gate electrode 2 is formed.
However, interfacial polarization occurs during the off time of the gate electrode 2.
This is because during the actual operation time of the liquid crystal display device, an OFF signal, that is, a negative voltage is applied to the gate of the TFT for most of the period except for a very short ON period when the TFT is selected, that is, a period when the gate is positive. The negative bias of this gate is formed on the back surface of the TFT and causes the interface polarization of the alignment film 7. Then, the interface polarization induces electrons in the semiconductor 4,
A current path is generated between the source electrode 5 and the drain electrode 6 even when the gate is off, which deteriorates the off characteristics of the TFT. The polarization component in the alignment film may be an intermediate product, a reaction precursor, or an impurity ion during the reaction for forming the alignment film, which is a phenomenon peculiar to the insulating material containing an organic material as a main component.
【０００６】図４は配向膜の界面分極の発生の様子を示
したＴＦＴの模式断面図である。ＴＦＴのオフ特性の劣
化については、エクステンディド アブストラクト ２
２コンファレンス ソリッドステイト デバイス アン
ド マテリアルズ、仙台、１０３９頁〜１０４２頁（Ｅ
ｘｔｅｎｄｅｄ Ａｂｓｔｒａｃｔｓ ｏｆ ｔｈｅ２
２ｎｄ（１９９０ Ｉｎｔｅｒｎａｔｉｏｎａｌ）Ｃｏ
ｎｆｅｒｅｎｃｅｏｎ Ｓｏｌｉｄ Ｓｔａｔｅ Ｄｅ
ｖｉｃｅｓ ａｎｄ Ｍａｔｅｒｉａｌｓ，Ｓｅｎｄａ
ｉ，ｐｐ１０３９−１０４２）に記載されているが、特
に液晶ディスプレイにおいてＴＦＴのオフ特性の劣化
は、画素単位の表示不良、例えば点欠陥につながり品質
上大きな問題となる。FIG. 4 is a schematic cross-sectional view of a TFT showing how the interfacial polarization of the alignment film occurs. For the deterioration of the TFT off characteristics, refer to Extended Abstract 2
2 Conference Solid State Device and Materials, Sendai, pp. 1039-1042 (E
XTENDED ABSTRACTS OF THE2
2nd (1990 International) Co
nferenceon Solid State De
Vices and Materials, Senda
i, pp1039-1042), the deterioration of the TFT OFF characteristics, particularly in a liquid crystal display, leads to display defects in pixel units, such as point defects, which is a serious problem in terms of quality.
【０００７】本発明では上記したＴＦＴからなる液晶表
示装置において、ゲート電極の直上部の配向膜の界面分
極による、ＴＦＴのオフ特性劣化の改善を図るものであ
る。In the present invention, in the liquid crystal display device including the above-mentioned TFT, it is intended to improve the OFF characteristic deterioration of the TFT due to the interface polarization of the alignment film immediately above the gate electrode.
【０００８】[0008]
【課題を解決するための手段】上記課題を解決するため
本発明の液晶表示装置は、配向膜を薄膜トランジスタの
ゲート電極の直上部を除いて形成した。In order to solve the above-mentioned problems, in the liquid crystal display device of the present invention, the alignment film is formed except for the portion right above the gate electrode of the thin film transistor.
【０００９】[0009]
【作用】ＴＦＴにおけるゲート電極の直上部を除いて、
有機材料を主成分とする絶縁材料からなる配向膜を形成
することにより、ゲート電極がオフ状態においても、ゲ
ート電極の直上部の配向膜の界面分極により、ＴＦＴの
オフ特性劣化が起こることがなくなる。[Function] Except immediately above the gate electrode in the TFT,
By forming an alignment film made of an insulating material containing an organic material as a main component, even when the gate electrode is in an off state, the off-characteristics of the TFT are not deteriorated due to the interface polarization of the alignment film immediately above the gate electrode. .
【００１０】[0010]
【実施例】以下に本発明の一実施例について図面を参照
しながら説明する。図１に、ゲート電極２、その上部に
形成されたゲート絶縁膜３、半導体膜４、ソース電極５
およびドレイン電極６からなるＴＦＴ群の中の１個の断
面図を示す。なお、図示していないが、前記ゲート電極
２にはゲート配線群、前記ソース電極５にはソース電極
群、前記ドレイン電極６には画素電極群がそれぞれ電気
的に接続されている。DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, a gate electrode 2, a gate insulating film 3, a semiconductor film 4, and a source electrode 5 formed on the gate electrode 2.
A sectional view of one of the TFT groups consisting of the drain electrode 6 and the drain electrode 6 is shown. Although not shown, a gate wiring group is electrically connected to the gate electrode 2, a source electrode group is electrically connected to the source electrode 5, and a pixel electrode group is electrically connected to the drain electrode 6.
【００１１】図１に示すように本実施例では、ゲート電
極２の直上部分を除いて配向膜７をＴＦＴ上に形成す
る。配向膜の形成は、印刷法によりゲート電極２の直上
部分を除いて印刷する方法、あるいは配向膜をＴＦＴ全
面に配向膜形成後、パターニングにより形成する。As shown in FIG. 1, in this embodiment, the alignment film 7 is formed on the TFT except the portion directly above the gate electrode 2. The alignment film is formed by a method of printing by removing a portion directly above the gate electrode 2 by a printing method, or by forming an alignment film on the entire surface of the TFT and then patterning.
【００１２】このようにして形成した本実施例のＴＦＴ
群からなる液晶表示装置の動作特性とＴＦＴ全面に配向
膜が形成された従来構成による液晶表示装置の動作特性
について図２に示す。図２は、液晶表示装置の表示特性
の劣化を起こさないゲート電圧のオフレベルの電位ＶGO
における、液晶表示装置の湿度動作試験による経時変化
について示したものである。通常ＶGOはオフ特性の劣化
にともない負の方向にシフトすることが知られている。
図２に示すように、ＴＦＴ全面に配向膜が形成された液
晶表示（従来例：点線で示す）では、動作時間５００時
間でＶGOが３Ｖ低下するのに比べ、ゲート電極直上部分
を除いて配向膜を形成した本実施例からなる液晶表示で
は（実線で示す）、動作時間５００時間でＶGOの変化は
０．３Ｖとなり、オフ特性について著しい改善が見られ
る。The TFT of this embodiment formed in this way
FIG. 2 shows the operating characteristics of the liquid crystal display device including the group and the operating characteristics of the conventional liquid crystal display device in which the alignment film is formed on the entire surface of the TFT. FIG. 2 shows an off-level potential V GO of the gate voltage that does not cause deterioration of display characteristics of the liquid crystal display device.
3 shows the change with time in the humidity operation test of the liquid crystal display device. It is generally known that V GO shifts in the negative direction as the OFF characteristic deteriorates.
As shown in FIG. 2, in a liquid crystal display in which an alignment film is formed on the entire surface of the TFT (conventional example: shown by a dotted line), V GO drops by 3 V at an operating time of 500 hours, except for the portion directly above the gate electrode. In the liquid crystal display according to the present example in which the alignment film is formed (shown by the solid line), the change in V GO becomes 0.3 V after 500 hours of operation, and the off characteristic is remarkably improved.
【００１３】[0013]
【発明の効果】以上実施例において説明したように本発
明の液晶表示装置を用いることにより、ＴＦＴのオフ特
性の劣化が改善でき、大幅な性能、信頼性の改善を図る
ことができる。As described in the above embodiments, by using the liquid crystal display device of the present invention, the deterioration of the off characteristics of the TFT can be improved, and the performance and reliability can be greatly improved.
【図１】本発明の一実施例による液晶表示装置の断面図FIG. 1 is a sectional view of a liquid crystal display device according to an embodiment of the present invention.
【図２】本発明の一実施例による液晶表示装置と従来構
成による液晶表示装置のオフ特性の動作時間による変化
を示す特性図FIG. 2 is a characteristic diagram showing changes in off characteristics of a liquid crystal display device according to an embodiment of the present invention and a liquid crystal display device having a conventional configuration according to operating time.
【図３】従来の液晶表示装置の断面図FIG. 3 is a sectional view of a conventional liquid crystal display device.
【図４】配向膜の界面分極の発生を示す液晶表示装置の
模式断面図FIG. 4 is a schematic cross-sectional view of a liquid crystal display device showing the occurrence of interfacial polarization of the alignment film.
１ 絶縁基板 ２ ゲート電極 ３ ゲート絶縁膜 ４ 半導体膜 ５ ソース電極 ６ ドレイン電極 ７ 配向膜 1 Insulating Substrate 2 Gate Electrode 3 Gate Insulating Film 4 Semiconductor Film 5 Source Electrode 6 Drain Electrode 7 Alignment Film
Claims (1)
て液晶を駆動する液晶表示装置であって、前記薄膜トラ
ンジスタのゲート電極の直上部を除いて配向膜を形成し
たことを特徴とする液晶表示装置。1. A liquid crystal display device in which a thin film transistor is used as a switching element to drive a liquid crystal, and an alignment film is formed on the thin film transistor except for a portion right above a gate electrode.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP28147692A JPH06202108A (en) | 1992-10-20 | 1992-10-20 | Liquid crystal display device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP28147692A JPH06202108A (en) | 1992-10-20 | 1992-10-20 | Liquid crystal display device |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH06202108A true JPH06202108A (en) | 1994-07-22 |
Family
ID=17639715
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP28147692A Pending JPH06202108A (en) | 1992-10-20 | 1992-10-20 | Liquid crystal display device |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH06202108A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2005024625A (en) * | 2003-06-30 | 2005-01-27 | Casio Comput Co Ltd | Liquid crystal display element |
| KR100480331B1 (en) * | 2002-04-08 | 2005-04-06 | 엘지.필립스 엘시디 주식회사 | Array Panel used for a Liquid Crystal Display and method for fabricating the same |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH02240637A (en) * | 1989-03-15 | 1990-09-25 | Matsushita Electric Ind Co Ltd | Liquid crystal image display device and production thereof |
-
1992
- 1992-10-20 JP JP28147692A patent/JPH06202108A/en active Pending
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH02240637A (en) * | 1989-03-15 | 1990-09-25 | Matsushita Electric Ind Co Ltd | Liquid crystal image display device and production thereof |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR100480331B1 (en) * | 2002-04-08 | 2005-04-06 | 엘지.필립스 엘시디 주식회사 | Array Panel used for a Liquid Crystal Display and method for fabricating the same |
| JP2005024625A (en) * | 2003-06-30 | 2005-01-27 | Casio Comput Co Ltd | Liquid crystal display element |
| JP4496724B2 (en) * | 2003-06-30 | 2010-07-07 | カシオ計算機株式会社 | Liquid crystal display element |
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