JPH05341327A - Liquid crystal display device - Google Patents

Abstract

PURPOSE:To obtain a MIM panel having the display quality better than the display quality of TFTs at a low cost by constituting nonlinear resistance elements as MIM elements consisting of a specific compsn. CONSTITUTION:This liquid crystal display device is provided with plural row electrodes provided on a substrate 1 and plural column electrodes disposed to intersect with the row electrodes on a counter substrate facing this substrate 1 and is disposed with the nonlinear resistance elements for switching in picture element parts formed in a matrix form in the parts where the row electrodes and the column electrodes intersect. Display is made by electrically driving the liquid crystal sealed between the substrates. Each of the nonlinear resistance elements is the MIM element, the lower electrode 3 of which consists of N-Ta, the element insulating film 4 of N-TaOx and the upper electrode 5 of N-Ta. In addition, N is incorporated at >=10atomic% into the N-TaOx of the element insulating film 4 in particular. Since the addition of the N by as much as the amt. necessary for the element insulating film 4 is possible, the display quality better than the display quality of the TFT element is obtainable.

Description

【発明の詳細な説明】Detailed Description of the Invention

【０００１】[0001]

【産業上の利用分野】本発明はＭＩＭ素子の構造に関す
る。The present invention relates to the structure of MIM devices.

【０００２】[0002]

【従来の技術】アクティブマトリックス液晶表示装置に
は大別してＴＦＴ方式、ＭＩＭ方式がある。ＴＦＴ方式
は各画素にＴＦＴ素子を配し液晶を駆動するもので、素
子スイッチングのオン、オフ比が大きく、またその温度
特性も良好なためコントラストやその温度特性の良い表
示装置が得られる。さらに表示容量を大きくすること
や、１画素に複数個のＴＦＴ素子を配し冗長性をもたせ
製造歩留まりを上げることも可能である。ただし５枚以
上のフォトマスクを使って５、６層の薄膜を積み重ねる
ため、製造工程が複雑で前述の冗長設計をしても充分に
製造歩留まりを上げられない、製造コストが高い等の欠
点も有する。そのため最近はＭＩＭ方式に代表される２
端子素子が注目されている。ＭＩＭは下電極Ｔａ、素子
絶縁膜ＴａＯｘ、上電極Ｃｒの構造で２、３枚のフォト
マスクしか使わないため製造工程がシンプルで基本的に
製造歩留まりが高い、製造コストが低い等の長所をも
つ。ただし素子オン、オフ比がＴＦＴ素子並みに大きく
なく、その温度特性も良くないため表示コントラストや
その温度特性はＴＦＴより劣っており、また十分にＭＩ
Ｍ素子に電圧を印加しスイッチングさせるために、素子
静電容量と液晶静電容量の比を２以上に設定しなくては
ならず、このためＴＦＴで実施されている１画素に複数
の素子を配する冗長設計やハイビジョン、ワークスティ
ション対応に表示容量を大きくすることも難しかった。2. Description of the Related Art TFTs and MIMs are roughly classified into active matrix liquid crystal display devices. In the TFT system, a TFT element is arranged in each pixel to drive a liquid crystal, and the ON / OFF ratio of element switching is large, and the temperature characteristic thereof is also good, so that a display device having good contrast and temperature characteristic can be obtained. Further, it is possible to increase the display capacity or to provide a plurality of TFT elements in one pixel to provide redundancy to increase the manufacturing yield. However, because five or more photomasks are used to stack thin films of five or six layers, the manufacturing process is complicated, and the manufacturing yield cannot be sufficiently increased even with the above-described redundant design, and the manufacturing cost is high. Have. Therefore, 2 recently represented by MIM method
Terminal elements are receiving attention. The MIM has a structure of a lower electrode Ta, an element insulating film TaOx, and an upper electrode Cr, and since only a few photomasks are used, the manufacturing process is simple and basically the manufacturing yield is high and the manufacturing cost is low. .. However, since the element on / off ratio is not as large as that of the TFT element and its temperature characteristic is not good, the display contrast and its temperature characteristic are inferior to those of the TFT, and the MI is sufficiently low.
In order to apply a voltage to the M element to switch it, the ratio of the element capacitance to the liquid crystal capacitance must be set to 2 or more. Therefore, a plurality of elements are mounted on one pixel implemented by the TFT. It was also difficult to increase the display capacity for redundant design, high-definition, and work station.

【０００３】しかし、これまでＭＩＭ素子について前述
の欠点を解消すべく”Ａｎ ＭＩＭ−ＬＣＤ ｗｉｔｈ
ＩｍｐｒｏｖｅｄＴＶ Ｐｅｒｆｏｒｍａｎｃｅ”Ｓ
ＩＤｄｉｇｅｓｔ １９９０や、”Ｔｈｅ Ｉｍｐｒｏ
ｖｅｄ Ｄｅｖｉｃｅ Ｃ−ｈａｒａｃｔｅｒｉｓｔｉ
ｃｓ ｏｆ ＭＩＭ−ＬＣＤ”ｔｈｅ ２２ｎｄＣｏｎ
ｆｅｒｅｎｃｅ ｏｎ ＳＯＬＩＤＳＴＡＴＥ ＤＥＶ
ＩＣＥＳ ＡＮＤＭＡＴＥＲＩＡＬＳ １９９０に示さ
れているように素子絶縁膜にＮを添加する試みがなされ
てきている。Ｎの添加により素子のオン、オフ比の向
上、素子静電容量の低下が達成され、コントラストやそ
の温度特性をＴＦＴに近づけることが可能となり、低製
造コストのままこれまでより高画質のＭＩＭパネルが得
られている。However, in order to overcome the above-mentioned drawbacks of MIM elements, "An MIM-LCD with"
ImprovedTV Performance "S
IDdigest 1990 and "The Impro
ved Device C-characteristics
cs of MIM-LCD "the 22ndCon
ference on SOLIDSTATE DEV
Attempts have been made to add N to the element insulating film as shown in ICES ANDMATTERIALS 1990. By adding N, the on / off ratio of the device is improved and the capacitance of the device is reduced, making it possible to bring the contrast and its temperature characteristics closer to that of a TFT, and with a lower manufacturing cost, a MIM panel with higher image quality than before. Has been obtained.

【０００４】[0004]

【発明が解決しようとする課題】しかし、前述の従来技
術では以下の課題を有している。素子絶縁膜へのＮの添
加量に比例して素子静電容量は低下し、オン、オフ比も
基本的に増大、組み立てられた表示体の品質も向上する
が、１０ａｔｏｍｉｃパーセント以上含有させると表示
にシミ状の欠陥を生ずるようになりそれ以上の表示品質
の向上が得られなくなる。これはＭＩＭ素子の構造が、
下電極Ｎ−Ｔａ、素子絶縁膜Ｎ−ＴａＯｘ、上電極Ｃｒ
であるため、素子絶縁膜にＮを多く含むことで素子絶縁
膜が表面粗さを増大し液晶中に含まれる水分を吸着しや
すくなり、上電極のＣｒが素子に流れる電流により電気
分解、素子特性が不安定となり組み立てられたＭＩＭ液
晶表示体にシミ状の欠陥を生ずるためである。これは液
晶中の水分量を１００ｐｐｍ以下に制御した場合であ
り、それ以上の水分を含む場合は更に低いＮ含有量で素
子特性異常を起こす。このことから、液晶中の水分量１
００ｐｐｍ以下と素子絶縁膜のＮ含有量１０ａｔｏｍｉ
ｃパーセント以下の厳重な管理が必要であり、それによ
ってもＭＩＭの表示コントラストは摂氏０度から５０度
で１００程度で、それ以上の温度では急激に下がってし
まいＴＦＴより表示品質が劣っているという課題を有す
る。ＴＦＴ並み、もしくはそれ以上の画質をＭＩＭで得
るためには素子絶縁膜に１０ａｔｏｍｉｃパーセント以
上のＮを添加させる必要がある。また素子複数化の冗長
設計による製造歩留まり向上や表示容量増大、ビューフ
ァインダーのような超微細画素に対応するためにはＭＩ
Ｍ素子の静電容量をＮを添加しないものの半分以下にし
なければならないが、そのためにも素子絶縁膜中のＮ添
加量を１０ａｔｏｍｉｃパーセント以上にしなくてはな
らず、これまでのＮ−Ｔａ、Ｎ−ＴａＯｘ、ＣｒのＭＩ
Ｍ構造では困難であるという課題を有していた。However, the above-mentioned prior art has the following problems. The device capacitance decreases in proportion to the amount of N added to the device insulating film, the on / off ratio basically increases, and the quality of the assembled display body also improves. Stain-like defects occur in the display, and further improvement in display quality cannot be obtained. This is because the structure of the MIM element is
Lower electrode N-Ta, element insulating film N-TaOx, upper electrode Cr
Therefore, when the element insulating film contains a large amount of N, the element insulating film increases the surface roughness and easily adsorbs moisture contained in the liquid crystal, and Cr of the upper electrode is electrolyzed by a current flowing through the element. This is because the characteristics become unstable and stain-like defects occur in the assembled MIM liquid crystal display. This is the case where the amount of water in the liquid crystal is controlled to 100 ppm or less, and when the amount of water is more than that, abnormal element characteristics occur with a lower N content. From this, the amount of water in the liquid crystal is 1
00ppm or less and N content of element insulating film 10 atomi
Strict control of c% or less is required, which also causes the display contrast of MIM to be about 100 at 0 to 50 degrees Celsius, and sharply drops at temperatures above that, resulting in poorer display quality than TFT. Have challenges. In order to obtain an image quality equal to or higher than that of TFT by MIM, it is necessary to add N of 10 atomic% or more to the element insulating film. In addition, in order to improve manufacturing yield and display capacity by redundant design with multiple elements, and to deal with ultra-fine pixels such as viewfinder, MI
The capacitance of the M element must be half or less than that of the element to which N is not added. For that purpose, the amount of N added in the element insulating film must be 10 atomic% or more. -TaOx, Cr MI
The M structure has a problem that it is difficult.

【０００５】そこで本発明はこれらの課題を解決するも
のであって、その目的とするところは低コストでＴＦＴ
以上の表示品質を持ったＭＩＭパネルを得ることにあ
る。Therefore, the present invention is intended to solve these problems, and its purpose is to reduce the cost of the TFT.
It is to obtain an MIM panel having the above display quality.

【０００６】[0006]

【課題を解決するための手段】本発明の液晶表示装置
は、基板上に設けられた複数の行電極と、前記基板と対
向する対向基板上に前記行電極と交差して配置された複
数の列電極が備えられ、前記行電極と前記列電極の交差
部のマトリックス状に形成された画素部にスイッチング
用非線形抵抗素子を配し、前記基板間に封入された液晶
を電気的に駆動させて表示する液晶表示装置において、
前記非線形抵抗素子が下電極Ｎ−Ｔａ、素子絶縁膜Ｎ−
ＴａＯｘ、上電極Ｎ−ＴａからなるＭＩＭ素子であり、
また特に前記素子絶縁膜Ｎ−ＴａＯｘのＮ含有量が１０
ａｔｏｍｉｃパーセント以上含まれていることを特徴と
する。A liquid crystal display device according to the present invention includes a plurality of row electrodes provided on a substrate and a plurality of row electrodes arranged on a counter substrate facing the substrate so as to intersect the row electrodes. Column electrodes are provided, switching nonlinear resistance elements are arranged in pixel portions formed in a matrix at intersections of the row electrodes and the column electrodes, and liquid crystals enclosed between the substrates are electrically driven. In the liquid crystal display device to display,
The non-linear resistance element includes a lower electrode N-Ta and an element insulating film N-.
A MIM element composed of TaOx and an upper electrode N-Ta,
Further, in particular, the N content of the element insulating film N-TaOx is 10
It is characterized in that it is contained in an atomic percentage or more.

【０００７】[0007]

【実施例】以下、本発明の実施例に基づき詳細に説明す
る。Embodiments will be described in detail below based on embodiments of the present invention.

【０００８】ＭＩＭ素子の構造を図２、図３に示す。図
２はＭＩＭ素子断面図、図３は図２に対応した上面図で
ある。Ｂａホウケイ酸ガラス１上にＴａＯｘを５００オ
ングストロームスパッタし下地絶縁膜２とした。スパッ
タ装置は徳田製作所製の５０Ｂを用いＴａをＡｒとＯ2
の混合雰囲気中でＤＣ成膜して得た。スパッタガスのそ
れぞれの分圧は０．３Ｐａであった。下地絶縁膜成膜後
スパッタプラズマを止め、一度チャンバー内を真空引き
してからＡｒ−１５％Ｎ2 ガスをスパッタチャンバー内
に１０ＳＣＣＭで導入した。ガス圧は０．７Ｐａとし３
０００オングストロームＤＣ成膜した。次に東京応化製
のＯＦＰＲ８００を１．４ミクロン塗布し摂氏９０度で
２０分ベーク後、露光現像し所定のレジストパターンを
得た。摂氏１２０度、３０分のポストベーク後４０％濃
度の弗酸と硝酸と水を体積比１：８：５の割合で混合し
た摂氏２０度のエッチャント中に浸漬、Ｎ−Ｔａ膜をエ
ッチパターニングし下電極３を形成した。エッチング時
間は１分でありレジストの剥離は無かった。次に東京応
化製のＳＴ−１０でレジストを剥離し０．１％のクエン
酸水溶液中で陽極酸化し６００オングストロームの素子
絶縁膜４を形成した。陽極酸化電圧は３３Ｖであった。
続いて、５０ＢにてＮ−Ｔａを１５００オングストロー
ムＤＣ成膜した。ただしスパッタ条件は、Ａｒ−１５％
Ｎ2 ガスをスパッタチャンバー内に３０ＳＣＣＭで導
入、ガス圧を０．７Ｐａとしており、そのほかの条件は
下電極３と同様であった。さらに下電極３と同様に所定
のレジストパターンを形成し、弗酸、硝酸、水の混酸を
用いエッチパターニング、上電極５を形成しＭＩＭ素子
とした。素子面積は１６平方ミクロンであった。レジス
ト剥離後ＩＬＣ−７０５にてＩＴＯを５００オングスト
ローム成膜し、同様に所定のレジストパターンを形成し
硝酸と塩酸の混酸水溶液でエッチング、画素電極６を形
成した。レジストを剥離しＭＩＭ素子基板を完成させ
た。また合わせて下電極Ｎ−Ｔａの成膜条件を変化させ
たＭＩＭ素子基板も作製した。Ａｒ−１５％Ｎ2 ガス流
量を２０から２００ＳＣＣＭまでそれぞれ１０ＳＣＣＭ
ごと変化させた１９水準のＭＩＭ素子を作製した。ガス
流量を変化させる際はオリフィスを操作しスパッタガス
圧は０．７Ｐａで一定になるようにし、その他の製造条
件は同じとした。The structure of the MIM element is shown in FIGS. 2 is a sectional view of the MIM element, and FIG. 3 is a top view corresponding to FIG. On the Ba borosilicate glass 1, TaOx was sputtered for 500 angstroms to form a base insulating film 2. The sputtering equipment is 50B manufactured by Tokuda Manufacturing Co., and Ta is Ar and O2.
It was obtained by DC film formation in a mixed atmosphere of. The partial pressure of each sputter gas was 0.3 Pa. After forming the underlying insulating film, the sputtering plasma was stopped, the chamber was evacuated once, and then Ar-15% N2 gas was introduced into the sputtering chamber at 10 SCCM. Gas pressure is 0.7 Pa and 3
A 000 Å DC film was formed. Next, OFPR800 manufactured by Tokyo Ohka Co., Ltd. was coated on 1.4 μm, baked at 90 ° C. for 20 minutes, and then exposed and developed to obtain a predetermined resist pattern. After post-baking for 30 minutes at 120 degrees Celsius, the N-Ta film is etched and patterned by immersing in an etchant at 20 degrees Celsius, which is a mixture of 40% hydrofluoric acid, nitric acid and water in a volume ratio of 1: 8: 5. The lower electrode 3 was formed. The etching time was 1 minute, and the resist was not peeled off. Next, the resist was peeled off at ST-10 manufactured by Tokyo Ohka Kogyo Co., Ltd., and anodized in a 0.1% aqueous citric acid solution to form a 600 angstrom element insulating film 4. The anodizing voltage was 33V.
Then, 1500 angstrom DC film of N-Ta was formed at 50B. However, the sputtering conditions are Ar-15%
N2 gas was introduced into the sputtering chamber at 30 SCCM, the gas pressure was 0.7 Pa, and other conditions were the same as those of the lower electrode 3. Further, a predetermined resist pattern was formed in the same manner as the lower electrode 3, and etching patterning was performed using a mixed acid of hydrofluoric acid, nitric acid and water, and the upper electrode 5 was formed to obtain a MIM element. The device area was 16 square microns. After the resist was peeled off, ITO was formed into a film of 500 angstrom by ILC-705, a predetermined resist pattern was formed in the same manner, and the pixel electrode 6 was formed by etching with a mixed acid solution of nitric acid and hydrochloric acid. The resist was peeled off to complete the MIM element substrate. In addition, an MIM element substrate in which the film forming conditions of the lower electrode N-Ta were changed was also manufactured. Ar-15% N2 gas flow rate from 20 to 200 SCCM, 10 SCCM each
19 levels of MIM elements which were changed every time were produced. When changing the gas flow rate, the orifice was operated so that the sputtering gas pressure was kept constant at 0.7 Pa, and the other manufacturing conditions were the same.

【０００９】さらに前述本発明の２０水準のＭＩＭ素子
上電極Ｎ−Ｔａ膜を、Ｃｒに変えたＭＩＭ素子を作製し
た。これらは従来技術によるものである。Ｃｒはアネル
バ製のＩＬＣ−７０５にて１５００オングストロームＤ
Ｃ成膜された。また他の電極と同様に膜上に所定のレジ
ストパターンを形成し、硝酸第２セリウムアンモン水溶
液にてエッチングして上電極５とした。そのほかの製造
条件は前述本発明の２０水準と同じとした。Further, an MIM element in which the above-mentioned 20-level MIM element upper electrode N-Ta film of the present invention was changed to Cr was manufactured. These are conventional techniques. Cr is 1500 Angstrom D with Anelva ILC-705
C film was formed. A predetermined resist pattern was formed on the film in the same manner as the other electrodes, and the upper electrode 5 was formed by etching with a cerium ammonium nitrate aqueous solution. The other manufacturing conditions were the same as the 20 levels of the present invention.

【００１０】次に対向基板としてＢａホウケイ酸ガラス
に染色カラーフィルター層Ｒ、Ｇ、Ｂを形成しその上に
シリコン変成ポリイミドを塗布焼成し、カラーフィルタ
ー層を平坦化した。さらにその上にＩＴＯをＭＩＭ基板
ＩＴＯと同様に（ただし膜厚だけ１０００オングストロ
ーム）成膜、パターニングし配線電極とした。Next, dyed color filter layers R, G, and B were formed on Ba borosilicate glass as a counter substrate, and silicon-modified polyimide was applied and baked on the dye color filter layers to flatten the color filter layer. Further thereon, ITO was formed and patterned in the same manner as the MIM substrate ITO (however, the film thickness was 1000 angstrom) and patterned to form a wiring electrode.

【００１１】以上で得られた両基板を、日本曹達社製ア
ミノシランＳＨ６０２０の０．１％水溶液中に浸せき
後、洗浄、摂氏１８０度で焼成した後、ラビングを行い
配向処理とした。セルギャップ保持材として径６ミクロ
ンのガラスファイバーを含んだ熱硬化タイプのエポキシ
樹脂をシール材としてＭＩＭ素子基板とカラーフィルタ
ー基板を貼合わせ摂氏１５０度、３時間圧着することで
液晶セルを得た。このセル中に真空注入法により液晶を
封入した。液晶の組成物はメルク社製のＰＣＨ（フェニ
ルシクロヘキサン）系液晶ＺＬＩ−１６９５を用いた。
この液晶セルの上下面に偏光板を貼ることで液晶表示パ
ネルを完成した。Both substrates obtained as described above were immersed in a 0.1% aqueous solution of aminosilane SH6020 manufactured by Nippon Soda Co., Ltd., washed, baked at 180 ° C., and rubbed for orientation treatment. A liquid crystal cell was obtained by laminating a MIM element substrate and a color filter substrate with a thermosetting type epoxy resin containing a glass fiber having a diameter of 6 μm as a sealing material as a cell gap maintaining material and press-bonding at 150 ° C. for 3 hours. A liquid crystal was enclosed in this cell by a vacuum injection method. As the composition of the liquid crystal, PCH (phenylcyclohexane) type liquid crystal ZLI-1695 manufactured by Merck was used.
A liquid crystal display panel was completed by pasting polarizing plates on the upper and lower surfaces of this liquid crystal cell.

【００１２】この４０水準のパネルを室温で１／４８０
ｄｕｔｙ駆動したところ、図１に示すようなコントラス
トが得られた。素子絶縁膜中のＮ含有量はＥＳＣＡ，Ｓ
ＩＭＳを用い測定した。下電極Ｎ−Ｔａ成膜時のＡｒ−
１５％Ｎ2 流量増加により素子絶縁膜中のＮ含有量がほ
ぼ比例して増大しているのがわかる。また素子絶縁膜中
のＮ濃度が１から１０ａｔｏｍｉｃパーセントまではＮ
濃度の増加に伴いパネルのコントラストもほぼ比例して
増加しており、これらの傾向に上電極の材質による差は
全く無かった。しかし上電極Ｎ−Ｔａの場合、パネルの
コントラストが素子絶縁膜のＮ濃度１０ａｔｏｍｉｃパ
ーセント以上でもそれ以下と同じ傾向で増加し約２７０
のコントラスト比を得ているのに対し、上電極Ｃｒの場
合、１０ａｔｏｍｉｃパーセントを越えたところからパ
ネルコントラストの増加が鈍くなり、約１５ａｔｏｍｉ
ｃパーセントでコントラスト比１１５を最大に、それ以
上のＮ濃度ではコントラストは減少に転じてしまった。
コントラスト比２７０のパネルを摂氏８０度で同じよう
に光学特性を測定したところ、コントラスト比２００を
得た。次にそれぞれのパネルを分解調査したところ、上
電極Ｎ−Ｔａのパネルでは全ての水準についてＭＩＭ素
子の異常は無かったが、上電極Ｃｒのパネルについては
素子絶縁膜のＮ濃度が１０ａｔｏｍｉｃパーセント以上
でＭＩＭ素子の上電極Ｃｒの異常が確認された。１０か
ら１５ａｔｏｍｉｃパーセントでは数千オングストロー
ム程度のＣｒ溶けがＳＥＭにて観察された。１５ａｔｏ
ｍｉｃパーセント以上では数ミクロンのＣｒ溶けが金属
顕微鏡でも観察され、液晶中からＣｒイオンが検出され
た。これより素子絶縁膜が１０ａｔｏｍｉｃパーセント
以上のＮを含んでいると液晶中の水分を素子絶縁膜が吸
着しやすくなり、上電極Ｃｒを液晶の駆動時に溶出させ
てしまうが、Ｔａであれば上電極は全く腐食されないた
め１０ａｔｏｍｉｃパーセント以上のＮを含んでいても
素子特性やパネルの表示品質に影響を及ぼさなく、素子
絶縁膜にＮを添加するだけパネルの表示品質を向上させ
ることが可能なことがわかる。また本実施例で上電極の
ＴａにもＮを添加したのは、弗酸と硝酸の混酸でエッチ
パターニングできるようにするためである。すなわち上
電極のパターニングをする際、素子絶縁膜とのエッチン
グレート比を相当大きくとらないと素子絶縁膜がエッチ
ングされ素子特性異常となるが、ドライエッチングでは
あまりその比を大きくできなく、前述のエッチャントを
用いたウェットエッチングではじめて可能となるのであ
る。ただしＴａ膜ははエッチングされるとき水素を発生
し自ら吸蔵、脆化し、剥離するので、Ｔａ格子間にＮを
侵入させＨの吸蔵を妨害するとともに、Ｔａのエッチャ
ントに対するエッチングレートを増大させ脆化する前に
パターニングを終了させてしまうためにＴａにＮを添加
するのである。This 40-level panel is 1/480 at room temperature.
When it was driven by duty, the contrast as shown in FIG. 1 was obtained. The N content in the element insulating film is ESCA, S
It measured using IMS. Ar-during lower electrode N-Ta film formation
It can be seen that the N content in the element insulating film increases almost in proportion to the increase in the 15% N2 flow rate. Further, when the N concentration in the element insulating film is 1 to 10 atomic percent,
The contrast of the panel also increased almost in proportion to the increase in the density, and there was no difference in these tendencies depending on the material of the upper electrode. However, in the case of the upper electrode N-Ta, the contrast of the panel increases in the same tendency even when the N concentration of the element insulating film is 10 atomic% or more, and is about 270 or less.
On the other hand, in the case of the upper electrode Cr, the increase in the panel contrast becomes slower from the point where it exceeds 10 atomic percent, and the contrast ratio becomes about 15 atomi.
The contrast ratio became the maximum at the c percentage, and the contrast started to decrease at the N concentration higher than that.
When the optical characteristics of a panel having a contrast ratio of 270 were measured in the same manner at 80 degrees Celsius, a contrast ratio of 200 was obtained. Next, when each panel was disassembled and examined, there was no abnormality in the MIM element at all levels in the panel of the upper electrode N-Ta, but in the panel of the upper electrode Cr, the N concentration of the element insulating film was 10 atomic% or more. Abnormality of the upper electrode Cr of the MIM element was confirmed. At 10 to 15 atomic percent, Cr melting of about several thousand angstroms was observed by SEM. 15ato
At a mic percentage or more, Cr dissolution of several microns was also observed with a metallurgical microscope, and Cr ions were detected in the liquid crystal. As a result, if the element insulating film contains 10 atomic% or more of N, it becomes easy for the element insulating film to adsorb moisture in the liquid crystal, and the upper electrode Cr will be eluted during driving of the liquid crystal. Since N is not corroded at all, even if it contains 10 atomic% or more of N, it does not affect the device characteristics or the display quality of the panel, and it is possible to improve the display quality of the panel simply by adding N to the device insulating film. Recognize. Further, in the present embodiment, N is also added to Ta of the upper electrode in order to enable etching patterning with a mixed acid of hydrofluoric acid and nitric acid. That is, when patterning the upper electrode, unless the etching rate ratio with the device insulating film is set to be considerably large, the device insulating film is etched and device characteristics become abnormal, but the ratio cannot be increased so much by dry etching, and the etchant described above is used. It becomes possible only by wet etching using. However, when the Ta film is etched, hydrogen is generated, so that the Ta film occludes and embrittles itself and peels off. Therefore, N penetrates into the Ta lattice to interfere with the occluding of H, and the etching rate of Ta to the etchant increases to embrittle. N is added to Ta in order to finish the patterning before the etching.

【００１３】以上より上電極をＮ−Ｔａとすることで、
ＴＦＴ以上の表示品質を持つ低コストＭＩＭパネルを得
ることができた。From the above, by making the upper electrode N-Ta,
It was possible to obtain a low-cost MIM panel having a display quality higher than that of the TFT.

【００１４】[0014]

【発明の効果】本発明によれば、素子絶縁膜に必要な量
だけＮを添加できるためＴＦＴ以上の表示品質が得ら
れ、またハイビジョン、ビューファインダーの領域まで
ＭＩＭの応用範囲を拡大し、更に画素の冗長化や製造条
件マージンの拡大による製造歩留まりの向上と基からの
ＭＩＭの簡易なプロセスと相まって製造コストを大幅に
下げることができた。According to the present invention, since N can be added in an amount necessary for the element insulating film, a display quality higher than that of a TFT can be obtained, and the application range of MIM is expanded to the areas of high-definition and viewfinder. The manufacturing cost was able to be drastically reduced in combination with the improvement of the manufacturing yield due to the redundancy of pixels and the expansion of the manufacturing condition margin and the simple process of MIM from the base.

【図面の簡単な説明】[Brief description of drawings]

【図１】 本発明の実施例におけるＭＩＭ素子上電極材
質の違いを示す、素子絶縁膜中のＮ濃度とパネルコント
ラスト比の関係図。FIG. 1 is a diagram showing the relationship between the N concentration in an element insulating film and the panel contrast ratio, showing the difference in the material of an electrode on an MIM element in an example of the present invention.

【図２】 ＭＩＭ素子の基本断面図。FIG. 2 is a basic sectional view of an MIM element.

【図３】 ＭＩＭ素子の基本上面図。FIG. 3 is a basic top view of an MIM element.

【符号の説明】[Explanation of symbols]

１ 基板 ２ 下地絶縁膜 ３ 下電極 ４ 素子絶縁膜 ５ 上電極 ６ 画素電極 1 substrate 2 base insulating film 3 lower electrode 4 element insulating film 5 upper electrode 6 pixel electrode

Claims (2)

【特許請求の範囲】[Claims] 【請求項１】 基板上に設けられた複数の行電極と、前
記基板と対向する対向基板上に前記行電極と交差して配
置された複数の列電極が備えられ、前記行電極と前記列
電極の交差部のマトリックス状に形成された画素部にス
イッチング用非線形抵抗素子を配し、前記基板間に封入
された液晶を電気的に駆動させて表示する液晶表示装置
において、前記非線形抵抗素子が下電極Ｎ−Ｔａ、素子
絶縁膜Ｎ−ＴａＯｘ、上電極Ｎ−ＴａからなるＭＩＭ素
子であることを特徴とする液晶表示装置。1. A plurality of row electrodes provided on a substrate, and a plurality of column electrodes arranged to intersect the row electrodes on a counter substrate facing the substrate, the row electrodes and the columns. In a liquid crystal display device in which a switching nonlinear resistance element is arranged in a pixel portion formed in a matrix shape at an intersection of electrodes, and a liquid crystal enclosed between the substrates is electrically driven to display, the nonlinear resistance element is A liquid crystal display device comprising a lower electrode N-Ta, an element insulating film N-TaOx, and an upper electrode N-Ta, which is an MIM element. 【請求項２】 前記素子絶縁膜Ｎ−ＴａＯｘのＮ含有量
が１０ａｔｏｍｉｃパーセント以上含まれていることを
特徴とする請求項１記載の液晶表示装置。2. The liquid crystal display device according to claim 1, wherein the N content of the element insulating film N-TaOx is 10 atomic% or more.