JPH0317996A - Thin film el element - Google Patents
Thin film el elementInfo
- Publication number
- JPH0317996A JPH0317996A JP1151840A JP15184089A JPH0317996A JP H0317996 A JPH0317996 A JP H0317996A JP 1151840 A JP1151840 A JP 1151840A JP 15184089 A JP15184089 A JP 15184089A JP H0317996 A JPH0317996 A JP H0317996A
- Authority
- JP
- Japan
- Prior art keywords
- thin film
- dielectric
- film
- layer
- dielectric thin
- 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
- 239000010409 thin film Substances 0.000 title claims abstract description 83
- 239000010408 film Substances 0.000 claims abstract description 29
- 238000010030 laminating Methods 0.000 claims abstract description 4
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 claims description 31
- 239000000758 substrate Substances 0.000 claims description 4
- 230000015556 catabolic process Effects 0.000 abstract description 14
- 230000005684 electric field Effects 0.000 abstract description 4
- 230000002950 deficient Effects 0.000 abstract description 3
- 238000001704 evaporation Methods 0.000 abstract description 3
- 230000007423 decrease Effects 0.000 abstract description 2
- 239000012141 concentrate Substances 0.000 abstract 1
- 239000010410 layer Substances 0.000 description 48
- 239000011572 manganese Substances 0.000 description 7
- 239000011159 matrix material Substances 0.000 description 6
- 238000004544 sputter deposition Methods 0.000 description 6
- 229910052984 zinc sulfide Inorganic materials 0.000 description 5
- 238000004020 luminiscence type Methods 0.000 description 4
- 238000000034 method Methods 0.000 description 4
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 description 3
- 230000008859 change Effects 0.000 description 3
- 230000006378 damage Effects 0.000 description 3
- 230000007547 defect Effects 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 description 2
- 229910052581 Si3N4 Inorganic materials 0.000 description 2
- UCKMPCXJQFINFW-UHFFFAOYSA-N Sulphide Chemical compound [S-2] UCKMPCXJQFINFW-UHFFFAOYSA-N 0.000 description 2
- 239000013543 active substance Substances 0.000 description 2
- 229910052788 barium Inorganic materials 0.000 description 2
- DSAJWYNOEDNPEQ-UHFFFAOYSA-N barium atom Chemical compound [Ba] DSAJWYNOEDNPEQ-UHFFFAOYSA-N 0.000 description 2
- BJXXCWDIBHXWOH-UHFFFAOYSA-N barium(2+);oxygen(2-);tantalum(5+) Chemical compound [O-2].[O-2].[O-2].[O-2].[O-2].[O-2].[O-2].[O-2].[O-2].[O-2].[O-2].[O-2].[O-2].[O-2].[O-2].[Ba+2].[Ba+2].[Ba+2].[Ba+2].[Ba+2].[Ta+5].[Ta+5].[Ta+5].[Ta+5] BJXXCWDIBHXWOH-UHFFFAOYSA-N 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 239000011521 glass Substances 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 229910003437 indium oxide Inorganic materials 0.000 description 2
- PJXISJQVUVHSOJ-UHFFFAOYSA-N indium(iii) oxide Chemical compound [O-2].[O-2].[O-2].[In+3].[In+3] PJXISJQVUVHSOJ-UHFFFAOYSA-N 0.000 description 2
- 229910052748 manganese Inorganic materials 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 description 2
- 229910052761 rare earth metal Inorganic materials 0.000 description 2
- HQVNEWCFYHHQES-UHFFFAOYSA-N silicon nitride Chemical compound N12[Si]34N5[Si]62N3[Si]51N64 HQVNEWCFYHHQES-UHFFFAOYSA-N 0.000 description 2
- VEALVRVVWBQVSL-UHFFFAOYSA-N strontium titanate Chemical compound [Sr+2].[O-][Ti]([O-])=O VEALVRVVWBQVSL-UHFFFAOYSA-N 0.000 description 2
- 241000287828 Gallus gallus Species 0.000 description 1
- 229910052777 Praseodymium Inorganic materials 0.000 description 1
- 238000009825 accumulation Methods 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 239000011575 calcium Substances 0.000 description 1
- -1 calcium sulfide Magnesium sulfide Zinc sulfide Chemical compound 0.000 description 1
- 229910017052 cobalt Inorganic materials 0.000 description 1
- 239000010941 cobalt Substances 0.000 description 1
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 238000009413 insulation Methods 0.000 description 1
- 230000005527 interface trap Effects 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 229910044991 metal oxide Inorganic materials 0.000 description 1
- 150000004706 metal oxides Chemical class 0.000 description 1
- 239000011224 oxide ceramic Substances 0.000 description 1
- 229910052574 oxide ceramic Inorganic materials 0.000 description 1
- BPUBBGLMJRNUCC-UHFFFAOYSA-N oxygen(2-);tantalum(5+) Chemical compound [O-2].[O-2].[O-2].[O-2].[O-2].[Ta+5].[Ta+5] BPUBBGLMJRNUCC-UHFFFAOYSA-N 0.000 description 1
- 238000000206 photolithography Methods 0.000 description 1
- PUDIUYLPXJFUGB-UHFFFAOYSA-N praseodymium atom Chemical compound [Pr] PUDIUYLPXJFUGB-UHFFFAOYSA-N 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 230000004044 response Effects 0.000 description 1
- 239000002356 single layer Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- PBCFLUZVCVVTBY-UHFFFAOYSA-N tantalum pentoxide Inorganic materials O=[Ta](=O)O[Ta](=O)=O PBCFLUZVCVVTBY-UHFFFAOYSA-N 0.000 description 1
- 230000007704 transition Effects 0.000 description 1
- 238000007740 vapor deposition Methods 0.000 description 1
Landscapes
- Electroluminescent Light Sources (AREA)
Abstract
Description
【発明の詳細な説明】
産業上の利用分野
本発明は 薄型で表示の視認性が優れ ＯＡ機器等の端
末ディスプレイとして最適である薄膜ＥＬ素子に関する
ものであり、更に詳しくは発光特性が長期にわたって安
定な薄膜ＥＬ素子に関すも従来の技術
従来より薄膜ＥＬ素子をＸ−Ｙマトリックス構戊にした
薄膜ＥＬディスプレイパネルが知られていも このパネ
ルは第１誘電体層／蛍光体層／第２誘電体層の積層薄膜
の両面に水平平行電極群と垂直平行電極群とを互いに直
交するように配置しそれぞれの電極群に接続された給電
線により、切り換え装置を通して信号を加えて両電極の
交点部分の蛍光体層を発光させ（この交点の発光部分面
を絵素と称する）、発光した絵素の組み合わせによって
文字記号 図形等を表示させるものであん上記薄膜ＥＬ
ディスプレイパネル（上 通常ガラス製の透光性基板上
に スズをドープした酸化インジウムからなる透明な平
行電極群を形或μ その上に第ｌ誘電体層、 蛍光体層
、 第２誘電体層を順次形威服 さらにその上に一般に
Ａｌ金属からなる背面平行電極群を前記透明平行電極群
に直交する配置で積層して作製すも
蛍光体層は一般にＺｎＳ母体に発光センターとしてＭｎ
や希土類元素等をドープしたちへ あるいはＣａＳやＳ
ｒＳ母体に発光センターとしてＣｅＳ Ｅｕ等をドーブ
したものが用いられも
第ｌ１第２誘電体層にはＹ２０ｓ、ｓｘｏ＊、Ａ１ａ＋
Ｏ＊、Ｔａ２０６、Ｓ＋ｔｎ○ｓ、ｓｉｓＮｔ、ＢａＴ
ｉＯ＊、ＳｒＴｉＯｓ、Ｐ ｂＴ ｉｏ ｓ、および１
３ａＴａａ○ｅ等から選ばれた誘電体薄膜が用いられも
誘電体層は蛍光体層の中を流れる電流を制御する電流
リミッターとしての働きを持＆ ＥＬディスプレイパ
ネルの電気的プレークダウンを防止し 耐電圧信頼性を
保つために重要であも
更に誘電体層は輝度一電圧特性（Ｂ／Ｖ特性）の経時変
化に対して大きな影響力を持＆ Ｂ／Ｖ特性が駆動時
間と共に変化すると画面が乱れたり、コントラスト特性
が悪くなるので、できる限りその経時変化が少なくなる
ような誘電体薄膜を選ばなくてはならな賎
発明が解決しようとする課題
しかしなが５１ｍｍあたり５本以上のマトリックス状電
極を有する高精細薄膜ＥＬバネルを駆動し 透明電極と
背面電極に挟まれた各絵素を発光させる場合、各絵素の
大きさ（．ｔ Ｏ． １６ｍｍｘＱ， １６ｍｍ
と、非常に小さくなるた幽 単層の誘電体層を用いた薄
膜ＥＬパネルを駆動した場合、ビンホール密度が多く、
駆動初期における絶縁破壊によって上記マトリクス状電
極の上部Ａ１電極が断線するという課題があった
本発明の目的（上 前記従来技術の課題を解決し高精細
ＥＬバネル製作後の初期駆動の際にも絶縁破壊が生じ家
長時間にわたり、安定した輝度一印加電圧特性を持つ
高輝嵐 かつ信頼性の高い薄膜ＥＬ素子を提供する事に
あも また薄膜相互の付着力が高く、高電圧の交流パル
スで駆動して転長時間にわたり、安定した輝度一印加電
圧特性を持つ薄膜ＥＬ素子を提供することを目的として
いも
課題を解決するための手段
本発明｛よ 透光性基板上に 透明電鳳 第ｌ誘電体層
、 蛍光体＃ 第２誘電体層および背面電極を順次積層
してなる薄膜ＥＬ素子において、第１誘電体層あるいは
第２誘電体層の膜構成を蛍光体層に接する面に輝度を低
下させない誘電体薄膜を設け、さらに比抵抗率が１０６
乃至１０１Ω・ｃｍの範囲にある高抵抗膜を蛍光体層に
対し外側に積層しさらにその外側に比抵抗率が１０１■
Ω・ｃｍ以上の絶縁性の誘電体薄膜を積層した多層膜と
するものであも
作用
本発明において、Ａ１電極の断線Ｇ＆ＥＬ素子駆動時に
誘電体膜のピンホール欠陥部分に電界が集中し最大蓄積
電荷量の大きい誘電体薄膜が破壊しその近辺の範囲のＡ
Ｉ電極を蒸発させ絵素の大きさ以上の穴を開け断線に至
る損傷を与えるために生じも これを解決するために
誘電体薄膜と高抵抗膜とを積層した多層膜構造とするこ
とによって、ビンホール密度が軽減され さらに例え誘
電体薄膜にあるピンホール欠陥部分に電界が集中したと
しても隣接する高抵抗膜によってエネルギーが欠陥の周
辺に分散しＡｌ電極を蒸発させずに初期駆動する際にも
絶縁破壊が生じない薄膜ＥＬ素子を製作することができ
も
一Ｘ 誘電体層による発光輝度負 発光開始電圧の変
動ｉ友 ＥＬ蛍光体層と誘電体層との界面に形戊される
トラップ準位の数や深さが誘電体層の種類によって異な
り、まｆ．ＥＬ素子の駆動に伴う新たなトラップ準位の
形或速度も異なる為に生じも これを解決するために
ＥＬ蛍光体層に接し 重要な界面を形戒する誘電体薄膜
を長時間にわたって安定した輝度一印加電圧特性を示す
ような誘電体薄膜を選択すも
以上説明したように ＥＬ素子の蛍光体層の両側に設け
る誘電体薄膜に輝度を低下させない誘電体薄膜と比抵抗
率が１０５乃至ｌＯ１Ω・ｃｍの範囲にある高抵抗膜と
さらに比抵抗率が１０１ＩΩ・ａｍ以上の絶縁性の誘電
体薄膜を積層した多層膜を用いることにより、初期の耐
電圧特性に優れた高輝度のＥＬ素子を作製できも
実施例
以下に 本発明の実施例について図面を参照しながら説
明すも
図は本発明にかかる薄膜ＥＬ素子の一実施例の断面構造
を示す。図において、ガラス基板１の上に合金ターゲッ
トを用いてインジウへ スズ混晶酸化物薄膜（以下ＩＴ
ＯＬｌ！！［と略称する）を直流スパッタ法で形戒レ
ホトリソグラフィ技術によりストライブ状に加工し 透
明電極２としたその上に 第１誘電体層３として比抵抗
率がｌＯ目Ω・ｃｍ以上の絶縁性の誘電体薄膜であるチ
タン酸ストロンチュームを主或分とした酸化物誘電体薄
膜を形威しｔも この厚さは２００ｎｍ乃至１０００
ｎｍであも 作製はＳｒ（ＴＬ Ｚｒ）Ｏｘの化学式
で表せるベロプス力イト形酸化物セラミックをターゲッ
トにした高周波マグネトロン活性スパッタ法を用いｔも
スパッタ雰囲気はＡｒ＋０２混合ガスを使用し１，
スパッタガスの圧力は２〜２０ｘｌＯ−”Ｔｏｒｒ
、基板温度は４５０℃乃至５５０ａ パワー密度は１
〜６ Ｗ／ ｃ ｍ”の範囲で作製した。その上に、Ｅ
Ｂ蒸着法でＣａＳの輝度を低下させない誘電体薄膜４を
２０乃至５０ｎｍの厚みで作製し、さらに蛍光体層５と
してＺｎＳ： Ｍｎ蛍光体薄膜を３００乃至１０００
ｎｍの厚さに形或した 発光センターのＭｎの含量は０
．８原子％にしｔも
蛍光体薄膜形戊後輝度アップのため真空雰囲気中で５５
０ｔ， １時間の熱処理を行うｔラつぎに輝度を低下
させない誘電体層６を蛍光体層５の上に前記の輝度を低
下させない誘電体層と全く同じ手法でＣａＳ薄膜を２０
乃至５０ｎｍの厚さに形或し１， さらに 第２誘電
体層として輝度を低下させない誘電体薄膜７としてタン
タル酸バリューム（ＢａＴａａ○●を主或分とした）薄
膜をスパッタ法で１００乃至５ ０ ０ ｎｍの範囲の
厚さで積層し、さらに高抵抗膜８としてプラセオジウム
とマンガンを含む酸化物薄膜を３００乃至１０００ｎｍ
の厚みでスバッタ法で形或し さらに 比抵抗率がｌ０
１Ω・ｃｍ以上の絶縁性の誘電体薄膜９として前記と同
様の比抵抗率が１０１１Ω・ｃｍ以上の値を持つタンタ
ル酸バリューム薄膜を１００乃至５ ０ ０ ｎｍ形戒
しｆＱ， 最後に背面電極１０としてアルミニウム薄
膜をＥＢ蒸着法で付けた後、ホトリソグラフィ技術でＩ
ＴＯ電極と直交するストライプ状に加工して薄膜ＥＬ素
子を完戒しｔ４本発明の一実施例にかかる上記薄膜ＥＬ
素子において、まず薄膜間の付着力と絶縁膜の緻密性に
ついて調べｔ４ 蛍光体薄膜を形威した後の熱処理中
の剥離と、ＥＬ素子駆動後の破壊状態を調べ１，熱処理
抵 薄膜間の剥離は全く観察されなかっ１，また 破壊
モード（よ いずれの場合も自己回復型であり低電界領
域に置ける破壊も認められｆ，ＥＬパネルの作製に適す
ることが分かっｔ４ また第２誘電体層を輝度を低下
させない誘電体薄膜と高抵抗膜と絶縁性の誘電体薄膜の
多層膜とする事によって、２５０ｖ以上の高電圧交流パ
ルスに対しての絶縁破壊によるＡ１電極の断線（上 従
来の誘電体層構或では断線していた電極線の幅が０．０
５ｍｍにしても全く起こらず信頼性が極めて高いことが
確認されｔも
次に高抵抗膜と絶縁性の誘電体薄膜との多層誘電体層を
有する薄膜ＥＬ素子と、従来用いられている単一の誘電
体薄膜を第１と第２誘電体層にそれぞれ使用した素子と
の比較を行っ？． この時用いた誘電体薄膜Ｃ上
窒化シリコン、酸化アルミニウム チタン酸ストロンチ
ウム タンタル酸バリウ八 五酸化タンタルを主或分と
した薄膜材料の中から選択しｔち また高抵抗膜とし
てＣ！ プラセオジウ八 二ッケ／１４ コバルト
、亜舷砥 クロ八 マンガンをいくつか含む金属酸化
物薄膜を用いた また 輝度を低下させない誘電体薄膜
としてＣヨ 硫化カルシウへ 硫化マグネシウム 硫
化亜鉛の硫化物薄膜と絶縁性の誘電体薄膜である酸化ア
ルミニウム 窒化シリコン、五酸化タンク）Ｉ＜タンタ
ル酸バリウムの中から選択しｔ４ 単一層の誘電体薄
膜を用いた従来の素子で（＆１００時間の６ ０ ０Ｈ
ｚの交流パルス電圧で駆動したとこ＆約７％発光しきい
電圧が移動したのに対し 本発明の薄膜ＥＬ素子では１
％以下であった これ１上蛍光体層に接する側に輝度を
低下させない誘電体薄膜として硫化物薄膜と絶縁性誘電
体薄膜の積層膜を設けたことにより従来のＥＬ素子より
優れた特性を示したものと考えられも
また 発光輝度１よ 蛍光体層に接する側に酸化膜誘電
体層を設けたＥＬ素子に比較して、 １．５乃至３倍の
高い値を示し１， 本発明のＥＬ素子は更にそれ以後
５０００時間ま玄 ほとんど発光しきい電圧や輝度の低
下は見られ哄 総合的に優れた発光特性を示し九 交流
パルス電圧の印加によって発光しきい電圧が移動するの
ζよ 蛍光体層と誘電体層の界面の界面トラップ単位の
分布や密度が駆動時間と共に変化したためと考えられ
この変化がＺｎＳ： Ｍｎ蛍光体層と輝度を低下させ
ない誘電体薄膜（ＣａＳ， ＭｇＳやＳｒＳ等）界面
では非常に抑えらへ 安定化しｆ，
さらに 本発明のＥＬ素子を駆動した初期状態における
絶縁破壊を防止する方法として実施例で挙げたように第
２誘電体層を輝度を低下させない誘電体薄膜（例えば蛍
光体層側に５０ｎｍのＣａＳと２００ｎｍのＢａＴａｔ
○●系薄膜）と高抵抗膜（例え＋ｉ３００乃至１０００
ｎｍのＰｒ−Ｍｎ−０系薄膜（比抵抗率が３〜６ｘｌＯ
”Ω・ｃｍで比誘電率が２００〜３００））と絶縁性の
誘電体薄膜（例えｌ；Ｕ２００ｎｍのＢ ａＴ ａ２０
●系薄膜）の多層薄膜とした 同じ厚さのＢ ａＴ ａ
ｓ Ｏｅ系薄羨に比較し、高抵抗膜の比誘電率が他の誘
電体薄膜や蛍光体薄膜と比較して２乃至１０倍程度高い
ため番ヘ発光開始しきい電圧もほとんど変化せずニＡ１
電極の絶縁破壊時の穴の開口径が半分以下 （１０μｍ
以下）で、しかも絶縁破壊による欠陥数（勿亀断線に至
らない）が１％以下と大幅に改善されｔラ高抵抗膜とし
てｔＬＰｒ−Ｍｎ一〇系以外に、比抵抗率が４ｘｌＯ’
〜ｌｘｌｏ” Ω・ｃｍの値をもっＰ ｒ − Ｎ
ｉ−○系の混合酸化物薄１１１Ｌ４ｘｌＯ″〜４ｘｌ
Ｏ’Ω”ａｍのＰ ｒ − Ｃ ｏ − ０系の混合酸
化物薄焦 Ｓ ｎｏ ｔ久 ＺｎＯ爪 等があも上記の
ように 本発明にかかる輝度を低下させない誘電体薄膜
と高抵抗膜と絶縁性の誘電体薄膜との多層誘電層薄膜を
用いることによって、初期の耐電圧特性に優れ 低駆動
電圧領域における微少破壊の全く生じない薄膜ＥＬ素子
を得１， 更に発光輝度の低下と発光しきい電圧の変
臥 薄膜間の剥離という駆動ならびに製造上の不安定要
素を無くすことができｔも
以上の説明において誘電体層の膜厚は薄膜ＥＬ素子によ
く用いられる１μｍ以下とした場合について記した 誘
電体層の膜厚は薄膜ＥＬ素子の目的とする輝度でほぼ決
定される蛍光体層の膜厚に従って変えねばならなＬ１
すなわち薄い蛍光体層の時は一般に薄い誘電体層でよ
鴇 本発明｛よ ＥＬ素子の絶縁破壊の生じない耐電圧
特性が満たされた高抵抗膜と誘電体薄膜のｌｊ！ｙＬＭ
構成であればよく、特に制限されるものではな鶏
ＥＬ蛍光体層５はＭｎ以外のたとえば希土類元素の活性
物質を含むＺｎＳ蛍光体？，ＣａＳやＳｒＳにＣｅやＥ
ｕの活性物質を含んだものに対しても本発明のＥＬ薄膜
構成は効果があっｔラ これは界面トラップ準位が蛍
光体母体と誘電体の種類でほぼ決まること、およびＣａ
ＳやＳｒＳ母体が特に蛍光体としてＺｎＳに似ているた
めであも
発明の効果
以上のように本発明によれば 耐電圧特性に優へ かつ
長時間の駆動によっても絶縁破壊による断線のなリ＼
発光しきい電圧の変動が極めて少ない高輝度の薄膜ＥＬ
素子を歩留りよく製造でき、コンピュータ端末などの薄
瓢 高品位ディスプレイとして広く利用でき、実用的価
値は大きｌ，％[Detailed Description of the Invention] Industrial Field of Application The present invention relates to a thin film EL element that is thin and has excellent display visibility and is ideal as a terminal display for office automation equipment, etc. More specifically, it relates to a thin film EL element that is thin and has excellent display visibility, and is ideal for terminal displays such as office automation equipment. Conventional technology regarding thin-film EL elementsAlthough thin-film EL display panels in which thin-film EL elements are arranged in an X-Y matrix structure have been known, this panel consists of a first dielectric layer/phosphor layer/second dielectric layer. A group of horizontal parallel electrodes and a group of vertical parallel electrodes are arranged perpendicularly to each other on both sides of the laminated thin film of the layer, and a signal is applied through a switching device using a feeder line connected to each electrode group to detect the intersection of both electrodes. The phosphor layer is made to emit light (the light-emitting surface at this intersection is called a picture element), and characters, symbols, figures, etc. are displayed by the combination of the emitted picture elements.
Display panel (top) A group of transparent parallel electrodes made of indium oxide doped with tin is formed on a transparent substrate, usually made of glass.A first dielectric layer, a phosphor layer, and a second dielectric layer are formed on top of the transparent parallel electrodes made of indium oxide doped with tin. Furthermore, a phosphor layer is fabricated by laminating a rear parallel electrode group generally made of Al metal in an arrangement orthogonal to the transparent parallel electrode group, but the phosphor layer is generally made of a ZnS matrix with Mn as a light emitting center.
or doped with rare earth elements, or CaS or S.
Although an rS matrix doped with CeS Eu or the like as a luminescence center is used, Y20s, sxo*, A1a+ is used in the l1 second dielectric layer.
O*, Ta206, S+tn○s, sisNt, BaT
iO*, SrTiOs, PbTios, and 1
Even if a dielectric thin film selected from 3aTaa○e etc. is used, the dielectric layer functions as a current limiter to control the current flowing through the phosphor layer & prevents electrical breakdown of the EL display panel. In addition to being important for maintaining voltage reliability, the dielectric layer has a large influence on changes in luminance-voltage characteristics (B/V characteristics) over time, and as the B/V characteristics change with driving time, the screen changes. However, it is necessary to choose a dielectric thin film that minimizes its change over time as much as possible.However, the problem that the invention aims to solve is that of matrix electrodes with five or more electrodes per 51 mm. When driving a high-definition thin film EL panel with
When driving a thin-film EL panel using a single dielectric layer, there is a large density of bin holes.
The object of the present invention is to solve the problem of the above-mentioned prior art, in which the upper A1 electrode of the matrix electrode is disconnected due to dielectric breakdown at the initial stage of driving. Our goal is to provide a highly reliable thin film EL device with stable brightness and applied voltage characteristics over a long period of time.Also, the adhesion between the thin films is high and it is driven by high voltage alternating current pulses. The present invention aims to provide a thin film EL device having stable luminance-applied voltage characteristics over a transition period of time. Body layer, phosphor # In a thin film EL device formed by sequentially laminating a second dielectric layer and a back electrode, the film structure of the first dielectric layer or the second dielectric layer is reduced in brightness on the surface in contact with the phosphor layer. A dielectric thin film is provided to prevent
A high resistance film in the range of 101Ωcm to 101Ωcm is laminated on the outside of the phosphor layer, and a specific resistivity of 101Ω is further layered on the outside.
In the present invention, when the A1 electrode is disconnected and the G&EL element is driven, the electric field is concentrated at the pinhole defective part of the dielectric film and the maximum accumulation occurs. A in the area near the breakdown of the dielectric thin film with a large amount of charge
In order to solve this problem, the I electrode is evaporated and a hole larger than the pixel size is created, causing damage that leads to wire breakage.
By using a multilayer film structure in which a dielectric thin film and a high-resistance film are laminated, the pinhole density is reduced, and even if an electric field is concentrated at a pinhole defect in the dielectric thin film, the energy is absorbed by the adjacent high-resistance film. It is possible to fabricate a thin film EL device that does not cause dielectric breakdown even during initial driving without evaporating the Al electrodes that are dispersed around defects.Negative luminance due to the dielectric layer.Fluctuation of luminescence starting voltage. The number and depth of trap levels formed at the interface between the EL phosphor layer and the dielectric layer vary depending on the type of dielectric layer, and f. This may occur due to the difference in the shape or speed of the new trap level that accompanies the driving of the EL element.To solve this problem,
The dielectric thin film that is in contact with the EL phosphor layer and forms an important interface is selected so that it exhibits stable brightness and applied voltage characteristics over a long period of time. The dielectric thin film provided on both sides is laminated with a dielectric thin film that does not reduce brightness, a high resistance film with a specific resistivity in the range of 105 to 101Ω・cm, and an insulating dielectric thin film with a specific resistivity of 101 IΩ・am or more. By using a multilayer film of this invention, a high-brightness EL element with excellent initial withstand voltage characteristics can be manufactured. 1 shows a cross-sectional structure of an example of an EL element. In the figure, an alloy target is used to deposit a tin mixed crystal oxide thin film (hereinafter referred to as IT) on a glass substrate 1.
OLl! ! [abbreviated as)] is formed using DC sputtering method.
The first dielectric layer 3 is made of strontium titanate, which is an insulating dielectric thin film with a specific resistivity of 10 Ω·cm or more, and is processed into a stripe shape using photolithography technology to form a transparent electrode 2. The thickness of the oxide dielectric thin film is 200 nm to 1000 nm.
The fabrication process was performed using high frequency magnetron active sputtering using a belopyrite-type oxide ceramic as a target, which can be expressed by the chemical formula Sr(TLZr)Ox.The sputtering atmosphere used an Ar+02 mixed gas.
The pressure of the sputtering gas is 2 to 20xlO-”Torr.
, substrate temperature is 450℃ to 550a, power density is 1
~6 W/cm". Furthermore, E
A dielectric thin film 4 that does not reduce the brightness of CaS is made with a thickness of 20 to 50 nm using the B vapor deposition method, and a ZnS:Mn phosphor thin film with a thickness of 300 to 1000 nm is further formed as a phosphor layer 5.
The Mn content of the luminescent center formed to a thickness of nm is 0.
．． To increase the brightness after forming a phosphor thin film with 8 at%, 55
Heat treatment is performed for 0 t and 1 hour. Next, a dielectric layer 6 that does not reduce the brightness is formed on the phosphor layer 5 using the same method as the dielectric layer that does not reduce the brightness.
A dielectric thin film 7 that does not reduce brightness is formed as a second dielectric layer to a thickness of 100 to 50 nm, and a tantalate barium (mainly composed of BaTaa○●) thin film is formed by sputtering to a thickness of 100 to 50 nm. A thin oxide film containing praseodymium and manganese is laminated to a thickness of 300 to 1000 nm as a high resistance film 8.
It is formed by the sputtering method with a thickness of
As an insulating dielectric thin film 9 of 1 Ω·cm or more, a tantalate barium thin film having a specific resistivity of 1011 Ω·cm or more is used as a thin film of 100 to 500 nm, fQ, and finally a back electrode 10. After attaching an aluminum thin film using EB evaporation method, I
The thin film EL element according to an embodiment of the present invention is manufactured by processing the thin film EL element into stripes perpendicular to the TO electrode.
In the device, we first investigated the adhesion between the thin films and the density of the insulating film.T4 We investigated the peeling during heat treatment after forming the phosphor thin film and the state of destruction after driving the EL element.1. No damage was observed1, and the breakdown mode (in both cases, self-healing type and breakdown that could be placed in a low electric field region) was found to be suitable for the production of EL panels. By using a multilayer film consisting of a dielectric thin film, a high resistance film, and an insulating dielectric thin film that does not reduce the voltage, disconnection of the A1 electrode due to dielectric breakdown in response to high voltage AC pulses of 250V or more (above) In the structure, the width of the disconnected electrode wire is 0.0
It was confirmed that this phenomenon did not occur at all even when the thickness was 5 mm, and that the reliability was extremely high. A comparison was made with a device using dielectric thin films of 1 and 2 for the first and second dielectric layers, respectively. ．． On the dielectric thin film C used at this time
Select from thin film materials mainly containing silicon nitride, aluminum oxide, strontium titanate, barium tantalate, and tantalum pentoxide. Also, as a high-resistance film, C! Cobalt, Submarine Black 8 A metal oxide thin film containing some manganese was used. Also, as a dielectric thin film that does not reduce brightness, C was used. To calcium sulfide Magnesium sulfide Zinc sulfide sulfide thin film and insulation In a conventional device using a single-layer dielectric thin film (aluminum oxide, silicon nitride, pentoxide tank) I < barium tantalate (600H for &100 hours)
When driven with an alternating current pulse voltage of
% or less. 1. By providing a laminated film of a sulfide thin film and an insulating dielectric thin film as a dielectric thin film that does not reduce brightness on the side in contact with the phosphor layer, it exhibits characteristics superior to conventional EL elements. It is also believed that the luminance of the EL device of the present invention is 1.5 to 3 times higher than that of an EL device in which an oxide film dielectric layer is provided on the side in contact with the phosphor layer. After that, the device was kept for 5,000 hours. There was almost no decrease in the luminescence threshold voltage or brightness, and it exhibited excellent overall luminescence characteristics.9 The luminescence threshold voltage shifts with the application of an AC pulse voltage. This is thought to be because the distribution and density of interface trap units at the interface between the layer and the dielectric layer changed with driving time.
This change is extremely suppressed and stabilized at the interface between the ZnS:Mn phosphor layer and a dielectric thin film (CaS, MgS, SrS, etc.) that does not reduce brightness, and furthermore, dielectric breakdown occurs in the initial state when the EL device of the present invention is driven. As a method for preventing this, as mentioned in the example, the second dielectric layer is coated with a dielectric thin film (for example, 50 nm of CaS and 200 nm of BaTat on the phosphor layer side) that does not reduce the brightness.
○● type thin film) and high resistance film (e.g. +i300 to 1000
nm Pr-Mn-0 thin film (specific resistivity 3-6xlO
"The dielectric constant is 200 to 300 in Ω cm)) and an insulating dielectric thin film (for example, U200 nm BaTa20)
●Multilayer thin film of the same thickness B aT a
Compared to s Oe-based thin films, the dielectric constant of the high-resistance film is about 2 to 10 times higher than that of other dielectric thin films or phosphor thin films, so the threshold voltage for starting light emission hardly changes. A1
The opening diameter of the hole at the time of dielectric breakdown of the electrode is less than half (10μm
(below), and the number of defects due to dielectric breakdown (not resulting in wire breakage) has been significantly improved to 1% or less.
~lxlo” with a value of Ω・cm P r − N
i-○ series mixed oxide thin 111L4xlO''~4xl
As mentioned above, the dielectric thin film and high-resistance film that do not reduce the brightness according to the present invention are By using a multilayer dielectric thin film with an insulating dielectric thin film, we have obtained a thin film EL element that has excellent initial withstand voltage characteristics and does not cause any microdestruction in the low driving voltage region. Variation of threshold voltage It is possible to eliminate the unstable element in driving and manufacturing, such as peeling between thin films. The thickness of the dielectric layer must be changed according to the thickness of the phosphor layer, which is approximately determined by the desired brightness of the thin film EL element.
In other words, when using a thin phosphor layer, it is generally necessary to use a thin dielectric layer.The present invention uses a high-resistance film and a dielectric thin film that satisfy the withstand voltage characteristics that do not cause dielectric breakdown of the EL element! yLM
There is no particular limitation as long as the structure is acceptable. Is the chicken EL phosphor layer 5 a ZnS phosphor containing an active substance other than Mn, such as a rare earth element? , Ce and E in CaS and SrS
The EL thin film structure of the present invention is effective even for materials containing active substances such as Ca.
Even though the S and SrS matrix is particularly similar to ZnS as a phosphor, the present invention has excellent withstand voltage characteristics and prevents disconnection due to dielectric breakdown even when driven for a long time. \
High-brightness thin-film EL with extremely little fluctuation in emission threshold voltage
The device can be manufactured with a high yield, and can be widely used as a thin, high-quality display for computer terminals, etc., and has a large practical value.
図は本発明にかかる一実施例の薄膜ＥＬ素子の構戊を示
す断面図であも
１・・・ガラス基楓 ２・ ・透明電颯 ３・・・第１
誘電体層、 ４、６、 ７・ ・輝度を低下させない誘
電体薄豚 ５・ ・蛍光体Ｎ．８・・高抵抗ＷＬ ９・
・絶縁性の誘電体薄ａ ｉｏ・・・背面電凰The figure is a cross-sectional view showing the structure of a thin film EL device according to an embodiment of the present invention.
Dielectric layer 4, 6, 7. Dielectric thin layer that does not reduce brightness 5. Phosphor N. 8. High resistance WL 9.
・Insulating dielectric thin aio...back panel
Claims (1)
、第２誘電体層および背面電極が順次積層された薄膜Ｅ
Ｌ素子において、前記第１誘電体層あるいは第２誘電体
層の膜構成が前記蛍光体層に接する面に輝度を低下させ
ない誘電体薄膜を設け、さらに比抵抗率が１０＾５乃至
１０＾９Ω・ｃｍの範囲にある高抵抗膜を前記蛍光体層
に対し外側に積層しさらにその外側に比抵抗率が１０＾
１＾■Ω・ｃｍ以上の絶縁性の誘電体薄膜を積層した多
層膜とされたことを特徴とする薄膜ＥＬ素子。A thin film E in which a transparent electrode, a first dielectric layer, a phosphor layer, a second dielectric layer, and a back electrode are sequentially laminated on a transparent substrate.
In the L element, the film structure of the first dielectric layer or the second dielectric layer includes a dielectric thin film that does not reduce brightness on the surface in contact with the phosphor layer, and further has a specific resistivity of 10^5 to 10^9 Ω.・A high resistance film in the range of cm is laminated on the outside of the phosphor layer, and a specific resistivity of 10^ is further placed on the outside of the phosphor layer.
A thin film EL device characterized in that it is a multilayer film made by laminating insulating dielectric thin films of 1^■Ω·cm or more.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1151840A JPH0317996A (en) | 1989-06-14 | 1989-06-14 | Thin film el element |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1151840A JPH0317996A (en) | 1989-06-14 | 1989-06-14 | Thin film el element |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH0317996A true JPH0317996A (en) | 1991-01-25 |
Family
ID=15527443
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP1151840A Pending JPH0317996A (en) | 1989-06-14 | 1989-06-14 | Thin film el element |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0317996A (en) |
-
1989
- 1989-06-14 JP JP1151840A patent/JPH0317996A/en active Pending
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