JP3647299B2 - Driving method and manufacturing method of electron-emitting device - Google Patents

Description

を求め、上記Ｓの値の変化率が５％以下になるまで、前記電圧Ｖ f1 を前記素子電極間に印加する工程であり、前記電圧印加工程終了直前において前記素子電極間に流れる電流Ｉ f1 と前記電流Ｉ f2 との関係がＩ f2 ≦０．７Ｉ f1 となるように、前記電圧印加工程における前記電圧Ｖ f1 を設定することを特徴とする。
【００１５】
【発明の実施の形態及び作用】
以下に、本発明の好ましい実施の形態および本発明の作用について述べる。
本発明を適用し得る表面伝導型電子放出素子の基本的構成には大別して、平面型及び垂直型の２つがある。
先ず、平面型表面伝導型電子放出素子について説明する。
図３は、本発明を適用可能な平面型表面伝導型電子放出素子の構成を示す模式図であり、図３（ａ）は平面図、図３（ｂ）は断面図である。図３において１は基板、２と３は素子電極、４は導電性薄膜、５は電子放出部である。
【００１６】
基板１としては、石英ガラス、Ｎａ等の不純物含有量を減少したガラス、青板ガラス、青板ガラスにスパッタ法等により形成したＳｉＯ₂ を積層したガラス基板、アルミナ等のセラミックス、及びＳｉ基板等を用いることができる。
対向する素子電極２、３の材料としては、一般的な導体材料を用いることができる。これは例えばＮｉ、Ｃｒ、Ａｕ、Ｍｏ、Ｗ、Ｐｔ、Ｔｉ、Ａｌ、Ｃｕ、Ｐｄ等の金属または合金及びＰｄ、Ａｇ、Ａｕ、ＲｕＯ₂ 、Ｐｄ−Ａｇ等の金属または金属酸化物とガラス等から構成される印刷導体、Ｉｎ₂ Ｏ₃ −ＳｎＯ₂ 等の透明導電体、及びポリシリコン等の半導体導体材料等から適宜選択することができる。
【００１７】
素子電極間隔Ｌ、素子電極長さＷ、導電性薄膜４の形状等は、応用される形態等を考慮して設計される。素子電極間隔Ｌは、好ましくは数百ｎｍから数百μｍの範囲とすることができ、より好ましくは、数μｍから数十μｍの範囲とすることができる。
素子電極長さＷは、電極の抵抗値、電子放出特性を考慮して、数μｍから数百μｍの範囲とすることができる。素子電極２、３の膜厚ｄは、数十ｎｍから数μｍの範囲とすることができる。
尚、図３に示した構成だけでなく、基板１上に、導電性薄膜４、対向する素子電極２、３の順に積層した構成とすることもできる。
【００１８】
導電性薄膜４には、良好な電子放出特性を得るために、微粒子で構成された微粒子膜を用いるのが好ましい。その膜厚は、素子電極２、３へのステップカバレージ、素子電極２、３間の抵抗値及び後述するフォーミング条件等を考慮して適宜設定されるが、通常は、数百ｐｍから数百ｎｍの範囲とするのが好ましく、より好ましくは１ｎｍより５０ｎｍの範囲とするのが良い。その抵抗値は、Ｒｓが１０² から１０⁷ Ω／□の値である。なおＲｓは、厚さがｔ、幅がｗで長さがｌの薄膜の抵抗Ｒを、Ｒ＝Ｒｓ（ｌ／ｗ）とおいたときに現れる量である。本明細書において、フォーミング処理については、通電処理を例に挙げて説明するが、フォーミング処理はこれに限られるものではなく、膜に亀裂を生じさせて高抵抗状態を形成する処理を包含するものである。
【００１９】
導電性薄膜４を構成する材料は、Ｐｄ、Ｐｔ、Ｒｕ、Ａｇ、Ａｕ、Ｔｉ、Ｉｎ、Ｃｕ、Ｃｒ、Ｆｅ、Ｚｎ、Ｓｎ、Ｔａ、Ｗ、Ｐｄ等の金属、ＰｄＯ、ＳｎＯ₂ 、Ｉｎ₂ Ｏ₃ 、ＰｂＯ、Ｓｂ₂ Ｏ₃ 等の酸化物、ＨｆＢ₂ 、ＺｒＢ₂ 、ＬａＢ₆ 、ＣｅＢ₆ 、ＹＢ₄ 、ＧｄＢ₄ 等の硼化物、ＴｉＣ、ＺｒＣ、ＨｆＣ、Ｔａ、Ｃ、ＳｉＣ、ＷＣ等の炭化物、ＴｉＮ、ＺｒＮ、ＨｆＮ等の窒化物、Ｓｉ、Ｇｅ等の半導体、カーボン等の中から適宜選択される。
【００２０】
ここで述べる微粒子膜とは、複数の微粒子が集合した膜であり、その微細構造は、微粒子が個々に分散配置した状態あるいは微粒子が互いに隣接、あるいは重なり合った状態（いくつかの微粒子が集合し、全体として島状構造を形成している場合も含む）をとっている。微粒子の粒径は、０．１ｎｍの数倍から数百ｎｍの範囲、好ましくは、１ｎｍから２０ｎｍの範囲である。
【００２１】
電子放出部５は、導電性薄膜４の一部に形成された高抵抗の亀裂により構成され、導電性薄膜４の膜厚、膜質、材料及び後述する通電フォーミング等の手法等に依存したものとなる。電子放出部５の内部には、０．１ｎｍの数倍から数十ｎｍの範囲の粒径の導電性微粒子が存在する場合もある。この導電性微粒子は、導電性薄膜４を構成する材料の元素の一部、あるいは全ての元素を含有するものとなる。電子放出部５及びその近傍の導電性薄膜４には、炭素及び炭素化合物を有することもできる。
【００２２】
次に、垂直型表面伝導型電子放出素子について説明する。
図４は、本発明の表面伝導型電子放出素子を適用できる垂直型表面伝導型電子放出素子の一例を示す模式図である。
図４においては、図３（ａ）ならび（ｂ）に示した部位と同じ部位には図３（ａ）ならび（ｂ）に付した符号と同一の符号を付している。６は、段差形成部である。基板１、素子電極２及び３、導電性薄膜４、電子放出部５は、前述した平面型表面伝導型電子放出素子の場合と同様の材料で構成することができる。段差形成部６は、真空蒸着法、印刷法、スパッタリング法等で形成されたＳｉＯ₂ 等の絶縁性材料で構成することができる。段差形成部６の膜厚は、先に述べた平面型表面伝導型電子放出素子の素子電極間隔Ｌに対応し、数百ｎｍから数十μｍの範囲とすることができる。この膜厚は、段差形成部の製法、及び素子電極間に印加する電圧を考慮して設定されるが、数十ｎｍから数μｍの範囲が好ましい。
【００２３】
導電性薄膜４は、素子電極２及び３と段差形成部６作成後に、該素子電極２、３の上に積層される。電子放出部５は、図４においては、段差形成部６に形成されているが、作成条件、フォーミング条件等に依存し、形状、位置ともこれに限られるものでない。
【００２４】
上述の表面伝導型電子放出素子の製造方法としては様々な方法があるが、その一例を図５に模式的に示す。
以下、図５〜図８を参照しながら製造方法の一例について説明する。図５においても、図３に示した部位と同じ部位には同一の符号を付している。
１）基板１を洗剤、純水および有機溶剤等を用いて十分に洗浄し、真空蒸着法、スパッタリング法等により素子電極材料を堆積後、例えばフォトリソグラフィー技術を用いて基板１上に素子電極２、３を形成する（図５（ａ））。
２）素子電極２、３を設けた基板１に、有機金属溶液を塗布して、有機金属薄膜を形成する。有機金属溶液には、前述の導電性膜４の材料の金属を主元素とする有機金属化合物の溶液を用いることができる。有機金属薄膜を加熱焼成処理し、例えば導電性薄膜形状に対応したマスクを用いてリフトオフを行う方法やエッチング等によりパターニングし、導電性薄膜４を形成する（図５（ｂ））。ここでは、有機金属溶液の塗布法を挙げて説明したが、導電性薄膜４の形成法はこれに限られるものでなく、真空蒸着法、スパッタ法、化学的気相堆積法、分散塗布法、ディッピング法、スピンナー法等を用いることもでき、インクジェット法等により直接パターニングを行うことも出来る。
【００２５】
３）続いて、フォーミング工程を施す。
フォーミング工程以降の電気的処理は図６に示したような、測定系を備えた真空容器内で行うことができる。
図６において、６１は真空容器であり、６２は素子に素子電圧を印加するための電源、６３は素子電極２、３間の導電性薄膜４を流れる素子電流Ｉf を測定する電流計、６４は電子放出部５より放出される放出電流Ｉe を捕捉するためのアノード電極、６５はアノード電極に電圧を印加するための高圧電源、６６は放出電流Ｉe を測定するための電流計、６７は真空容器６１内を排気する排気装置、６８は活性化物質収容容器である。
【００２６】
基板１を真空容器６１内に設置し、真空容器内を排気した後、素子電極２、３間に、電圧を印加すると、導電性薄膜４の部位に、構造の変化した電子放出部５が形成される（図５（ｃ））。通電フォーミングによれば導電性薄膜４に局所的に破壊、変形もしくは変質等の構造の変化した部位が形成される。該部位が電子放出部５を構成する。通電フォーミングの電圧波形の例を図７に示す。
電圧波形は、パルス波形が好ましい。これにはパルス波高値を増加させながら、電圧パルスを印加する図７（ａ）に示した手法と、パルス波高値を定電圧としたパルスを連続的に印加する図７（ｂ）に示した手法がある。
【００２７】
図７（ａ）におけるＴ1 及びＴ2 は、電圧波形のパルス幅とパルス間隔である。通常Ｔ1 は１μsec 〜１０ｍsec 、Ｔ2 は１０μsec 〜１０ｍsec の範囲で設定される。パルスの波高値は、例えば０．１Ｖステップ程度ずつ増加させることができる。通電フォーミング処理の終了は、例えば導電性薄膜４が局所的に破壊、変形することによって生じる抵抗値の変化を読み取ることで判断することが出来、一例として、パルス間隔Ｔ2 中に、導電性薄膜４を局所的に破壊、変形しない程度の電圧を印加し、電流を測定して検知することができる。例えば０．１Ｖ程度の電圧印加により流れる素子電流を測定し、抵抗値を求めて、１ＭΩ以上の抵抗を示した時、通電フォーミングを終了させる。パルス波形は矩形波に限定されるものではなく、三角波など所望の波形を採用することができる。
【００２８】
図７（ｂ）におけるＴ1 及びＴ2 は、図７（ａ）に示したのと同様とすることができる。パルスの波高値は、表面伝導型電子放出素形態に応じて適宜選択される。このような条件のもと、例えば、数秒から数十分間電圧を印加する。パルス波形は矩形波に限定されるものではなく、三角波など所望の波形を採用することができる。
【００２９】
４）フォーミングを終えた素子には活性化工程と呼ばれる処理を施すのが好ましい。活性化工程とは、この工程により素子電流Ｉf 、放出電流Ｉe が、著しく変化する工程である。
活性化工程は、例えば、有機物質のガスを含有する雰囲気下で、通電フォーミングと同様に、パルス電圧の印加を繰り返すことで行うことができる。パルス電圧としては、図７に示した電圧パルスの他、図８に示した両極性の電圧パルスを用いることができる。
【００３０】
活性化雰囲気は、例えば油拡散ポンプやロータリーポンプなどを用いて真空容器６１内を排気した場合に雰囲気内に残留する有機ガスを利用して形成することができる他、イオンポンプなどにより一旦十分に排気した真空中に、活性化物質収容容器６８より適当な有機物質のガスを導入することによっても得られる。このときの好ましい有機物質のガス圧は、前述の応用の形態、真空容器の形状や、有機物質の種類などにより異なるため場合に応じ適宜設定される。適当な有機物質としては、アルカン、アルケン、アルキンの脂肪族炭化水素類、芳香族炭化水素類、アルコール類、アルデヒド類、ケトン類、アミン類、フェノール、カルボン、スルホン酸等の有機酸類等を挙げることが出来、具体的には、メタン、エタン、プロパン等の飽和炭化水素、エチレン、プロピレン等の不飽和炭化水素、ブタジエン、ｎ−ヘキサン、ｌ−ヘキセン、ベンゼン、トルエン、Ｏ−キシレン、ベンゾニトリル、トルニトリル、クロロエチレン、トリクロロエチレン、メタノール、エタノール、イソプロパノール、ホルムアルデヒド、アセトアルデヒド、アセトン、メチルエチルケトン、ジエチルケトン、メチルアミン、エチルアミン、酢酸、プロピオン酸等あるいはこれらの混合物が使用できる。この処理により、雰囲気中に存在する有機物質から、炭素あるいは炭素化合物が素子上に堆積し、素子電流Ｉf 及び放出電流Ｉe が著しく変化するようになる。
【００３１】
活性化工程の終了判定は、素子電流Ｉf や放出電流Ｉe を測定しながら適宜行う。なお、パルス幅、パルス間隔、パルス波高値などは適宜設定される。
【００３２】
５）このような工程を経て得られた電子放出素子は、安定化工程を行うことが好ましい。この工程は、電子放出素子の表面に吸着した有機物質、および電子放出素子を内包する真空容器内の有機物質を除去し、電子放出素子を駆動しても、新たに上述の炭素及び炭素化合物が堆積しないようにする工程である。真空容器を排気する真空排気装置は、装置から発生するオイル等の有機物質が素子の特性に影響を与えないように、オイルを使用しないものを用いるのが好ましい。具体的には、磁気浮上型ターボ分子ポンプ、クライオポンプ、ソープションポンプ、イオンポンプ等の真空排気装置を挙げることが出来る。
【００３３】
真空容器内の有機成分の分圧は、上述の炭素及び炭素化合物がほぼ新たに堆積しない分圧で１×１０^-6Ｐａ以下が好ましく、さらには１×１０^-8Ｐａ以下が特に好ましい。さらに真空容器内を排気するときには、真空容器全体を加熱して、真空容器内壁や、電子放出素子に吸着した有機物質分子を排気しやすくするのが好ましい。このときの加熱条件は、８０〜２５０℃好ましくは１５０℃以上で、できるだけ長時間処理するのが望ましいが、特にこの条件に限るものではなく、真空容器の大きさや形状、電子放出素子の構成などの諸条件により適宜選ばれる条件により行う。真空容器内の圧力は極力低くすることが必要で、１×１０^-5Ｐａ以下が好ましく、さらに１×１０^-6Ｐａ以下が特に好ましい。
【００３４】
安定化工程を行った後の、駆動時の雰囲気は、上記安定化処理終了時の雰囲気を維持するのが好ましいが、これに限るものではなく、有機物質が十分除去されていれば、真空容器の圧力は多少上昇してもある程度安定な特性を維持することが出来る。
このような真空雰囲気を採用することにより、新たな炭素あるいは炭素化合物の堆積を抑制でき、また真空容器や基板などに吸着したＨ₂ＯやＯ₂ なども除去でき、結果として素子電流Ｉf 及び放出電流Ｉe が比較的安定するものである。
【００３５】
上述した工程を経て得られた電子放出素子の基本特性について説明する。
まず、電子放出素子の動作特性の典型例を図１に模式的に示す。
図１は、素子に印加する素子電圧Ｖf に対する、素子に流れる電流（素子電流）Ｉf と、電子放出部より放出される電流（放出電流）Ｉe の関係を模式的に示した図である。なお、Ｉe の値はＩf に比べて極めて小さいため、それぞれ任意目盛で示してある。但し、いずれの目盛もリニアスケールである。
【００３６】
素子電流Ｉf と放出電流Ｉe の測定には、図６に示した真空装置を用いることができ、例えば、アノード電極の電圧を１ｋＶ〜１０ｋＶの範囲とし、アノード電極６４と電子放出素子との距離Ｈを２ｍｍ〜８ｍｍの範囲として測定を行うことができる。
【００３７】
図１からも明らかなように、本発明を適用可能な表面伝導型電子放出素子は、放出電流Ｉe に関して以下の三つの特徴的性質を有する。
即ち、
（ｉ）本素子はある電圧（しきい値電圧と呼ぶ、図１中のＶth）以上の素子電圧を印加すると急激に放出電流Ｉe が増加し、一方しきい値電圧Ｖth以下では放出電流Ｉe がほとんど検出されない。つまり、放出電流Ｉe に対する明確なしきい値電圧Ｖthを持った非線形素子である。
（ii）放出電流Ｉe が素子電圧Ｖf に単調増加依存するため、放出電流Ｉe は素子電圧Ｖf で制御できる。
（iii)アノード電極に捕捉される放出電荷は、素子電圧Ｖf を印加する時間に依存する。つまり、アノード電極に捕捉される電荷量は、素子電圧Ｖf を印加する時間により制御できる。
【００３８】
図１では、Ｉf もＩe と同様に、Ｖf に対する閾値を持ち、閾値以上のＶthに対しＩf が単調増加する場合（ＭＩ特性）を示したが、製造工程や、測定条件によっては、Ｉf が電圧制御型負性抵抗を示す場合（ＶＣＮＲ特性）もある。ＶＣＮＲ特性を示す場合は、そのＩf −Ｖf 特性は安定ではなく、この場合にもＩe はＭＩ特性を示すが、やはり安定ではない。この場合も、安定化工程を施すことにより、安定なＭＩ特性を示す様にすることができる。
【００３９】
安定化工程を施した電子放出素子においては、素子電流Ｉf 、放出電流Ｉe は素子電圧Ｖf に対してＭＩ特性を有し、素子電圧Ｖf に対して素子電流Ｉf および放出電流Ｉe が一義的に決まる特性を有する。またこの時のＩf −Ｖf 特性、Ｉe −Ｖf 特性は、安定化工程後に印加された最大電圧Ｖmax に依存することを本発明者らは見出している。
【００４０】
この電子放出素子のＩ−Ｖ特性について、図２（ａ）、（ｂ）を用いて説明する。図２（ａ）はＩf とＶf の関係を示した図であり、図２（ｂ）はＩe とＶf との関係を示した図である。
図２（ａ）、（ｂ）において、実線で示されるのは、最大電圧Ｖmax ＝Ｖmax1で駆動した素子のＩ−Ｖ特性である。この素子をＶmax1以下の素子電圧で駆動する時には、この実線で示されるＩ−Ｖ特性と同じＩ−Ｖ特性を有する。しかし、Ｖmax1以上の電圧Ｖmax2で駆動すると、素子は図中破線で示されるように異なるＩ−Ｖ特性を示すようになり、この素子をＶmax2以下の素子電圧で駆動する時には、この破線で示されるＩ−Ｖ特性と同じＩ−Ｖ特性を有するようになる。これは、電子放出素子に印加される最大電圧Ｖmax によって、電子放出部の形状や電子放出面積等が変化するためと考えられる。
【００４１】
本発明の駆動方法では、安定化工程を終えた電子放出素子を駆動するのにあたり、まず素子電圧Ｖf1 なる電圧で素子を駆動する（以降この駆動を「予備駆動」と呼ぶ）。これにより、電子放出素子は図１に示すようにＶmax ＝Ｖf1 なる電圧によって一義的に決められるＩf −Ｖf 特性およびＩe −Ｖf 特性を有するようになる。
次に、予備駆動終了時の素子電圧Ｖf1における素子電流をＩf1とし、予備駆動により決められたＩf −Ｖf 特性より、Ｉf2≦０．７Ｉf1となるＶf2を選択し駆動電圧とする（図１中のＶf2）。
【００４２】
素子電圧Ｖf1で予備駆動を行った素子に、上述のようにＩf2≦０．７Ｉf1となる駆動電圧Ｖf2を印加しても、電子放出部の形状や放出面積の変化はほとんど生じないと考えられるため、駆動時においては、予備駆動時とほぼ同じ放出面積を有しながら、予備駆動時よりも低い素子電流Ｉf で駆動することになる。そのため、駆動時に電子放出部に流れる素子電流の電流密度を下げることができ、電子放出部の熱的な劣化を抑え、長時間安定に電子放出させることができるものと考えられる。
【００４３】
安定な放出電流が得られる時間は、予備駆動時と駆動時のＩf の差の割合（Ｉf1−Ｉf2）／Ｉf1に対してほぼ指数関数的に変化する傾向が見られる。上述の素子においては、素子の製造条件等にも依存するが、駆動Ｉf をＩf1に対して１０％小さくする毎に、安定な放出電流が得られる時間は５〜１０倍程度長くなる。従って、Ｉf2≦０．７Ｉf1となる電圧で駆動することにより、定電圧で駆動した場合に比べて、安定な放出電流が得られる時間を概ね２桁以上長くすることができ、安定性を大幅に向上させることができる。
【００４４】
上記予備駆動は、予備駆動後に予備駆動電圧よりも低い電圧で駆動する際に、電子放出素子のＩf −Ｖf 特性およびＩe −Ｖf 特性が変化しないために必要な時間行えばよく、パルス幅が数μsec 〜数十ｍsec 、好ましくは１０μsec 〜１０ｍsec のパルス電圧を数パルス〜数十パルス以上印加することにより、行うことができる。
【００４５】
また、例えば以下の方法により予備駆動に必要な時間を決めることができる。上述の工程により作成される電子放出素子のＩf −Ｖf 特性を、１／Ｖf に対してlog(Ｉf ／Ｖf²）をプロット(Fowler-Nordheim Plots) すると、図９に示すようにほぼ直線の関係が得られる。
【００４６】
従って上記予備駆動時に、｜Ｖf11｜≦｜Ｖf1｜である電圧Ｖf11と、Ｖf11よりも微少電圧ｄＶ絶対値の小さい電圧Ｖf12を連続して印加（例えばＶf11＝Ｖf1、Ｖf12＝Ｖf1−ｄＶ）し、それぞれの電圧を印加した時に流れる電流Ｉf11 、Ｉf12より、図９における傾きＳ
【００４７】
【数４】

を求め、傾きＳの値の変化率をみることにより、電子放出素子のＩf −Ｖf 特性の変化をみることができる。本発明者らの実験によれば、上記傾きＳの値の変化率が５％以下になるまでの時間予備駆動を行えば、その後の駆動において、上記傾きＳの値はほぼ一定となり、予備駆動の効果がみられる。よって、上記傾きＳの値の変化率が５％以下になるまでの時間予備駆動を行えばよい。
【００４８】
予備駆動における電圧波形としては、図１０（ａ）、（ｂ）、（ｃ）に示すような電圧波形を用いることができる。図１０（ａ）は予備駆動電圧Ｖf1をＴ1 時間印加した直後に電圧Ｖf12までＴ12時間かけて電圧が変化する電圧波形である。図１０（ｂ）は、予備駆動電圧Ｖf1をＴ1 時間印加した直後に電圧Ｖf12をＴ12時間印加する電圧波形である。また、図１０（Ｃ）は、予備駆動電圧Ｖf1 をＴ1 時間印加した後にＶf12の電圧をＴ12時間印加する電圧波形である。それぞれの電圧（ここではＶf11＝Ｖf1）印加時に流れる素子電流Ｉf1（ここではＩf11＝Ｉf1）、Ｉf12 より上記傾きＳの変化率を求め、予備駆動に必要な時間を求めることができる。
【００４９】
なお、この予備駆動は、通常、製造工程の最終段階、例えば安定化工程の後または安定化工程の一環として行われるが、在庫後出荷前のリフレッシュ工程として、または電子放出素子の使用開始後的適宜のリフレッシュモードとして行うことも可能である。
【００５０】
【実施例】
以下、実施例を挙げて、本発明をさらに詳述する。
（実施例１）
本実施例は、図３に模式的に示したものと同様の構成を有する電子放出素子に対して、本発明の駆動方法を適用した例である。図５に基づき、本実施例で用いられる電子放出素子の製造方法を説明する。
【００５１】
まず、工程−ａ〜工程−ｅにより基板１上に素子Ａ〜Ｅの５個の電子放出素子を作成した。
工程−ａ（図５の（ａ））
石英基板からなる基板１を洗浄後、スパッタリング法により基板１上に５ｎｍのＴｉと５０ｎｍのＰｔを堆積した。その後、堆積膜上にフォトレジストを塗布し、素子電極対２並びに３に対応する形状のパターンを形成した後、エッチングにより不要な部分のＰｔとＴｉを除去し、その後レジストを除去することで基板１上に素子電極２、３を形成した。なお、素子電極２、３間の間隔Ｌは１０μｍ、素子電極の長さＷは３００μｍとした。
【００５２】
工程−ｂ（図５の（ｂ））
素子電極２、３を設けた基板１上に、真空蒸着により厚さ５０ｎｍのＣｒを堆積し、このＣｒ膜に対してフォトリソグラフィー技術を用いて導電性薄膜を形成する位置に対応した開口部を形成する。その後、有機Ｐｄ化合物の溶液（ｃｃｐ−４２３０：奥野製薬（株）製）を塗布し、大気中で３００℃の加熱処理を施した。次に、Ｃｒ膜をウエットエッチにより除去し、純水で洗浄後乾燥し、導電性薄膜４を形成した。
【００５３】
以降の工程は、製造工程中の電子放出素子を図６に示すような真空容器内に配置し、電気的接続を行った後実施した。図６に示すように、素子電極３はグランド電位に接続し、素子電極２は電流導入端子を通じて電流計６３並びに素子電圧電源６２に接続している。また、基板１の５ｍｍ上方にアノード電極を配置し、アノード電極６４は電流導入端子を通じて電流計６６並びに高圧電源６５に接続している。
【００５４】
工程−３ｃ
真空容器内を、スクロールポンプ並びにターボ分子ポンプを用いて、１×１０^-3Ｐａ以下程度まで排気した後、素子電圧電源で発生させた電圧を素子電極２に印加し、フォーミング処理を施し電子放出部５を形成した。印加した電圧は図７（ａ）に示すようにパルス状の電圧であり、時間の経過とともに波高値の漸増するパルスである。パルス幅Ｔ1 は１ｍsec とし、パルス間隔Ｔ2 は１６．７ｍsec とした。フォーミング処理中、パルス波高値が６Ｖに達した時点で電流計を流れる電流値が激減した。その後、パルス波高値が６．５Ｖになるまでパルス電圧を印加した後、電圧の印加を停止し、素子電極２、３間の抵抗値を測定したところ、１ＭΩ以上の値を示したため、フォーミング処理を終了した。
【００５５】
工程−３ｄ
真空容器内の排気を更に継続し、容器内圧力が１０^-5Ｐａ以下まで減少した後、真空容器内にベンゾニトリルガスを導入して活性化工程を行った。活性化工程は、活性化ガスを導入した真空容器内圧力が１．３×１０^-4Ｐａになるように調節し、素子電圧電源で発生させた電圧を素子電極２に印加することで行った。印加した電圧は図８に示すように両極性のパルス電圧であり、波高値が一定のパルスである。パルス波高値は１６Ｖとし、パルス幅Ｔ1 は１ｍsec とし、パルス間隔Ｔ2 は２０ｍsec とした。活性化処理は１時間行い、その後電圧の印加を停止し、活性化ガスの導入を停止して真空容器内より活性化ガスを排気した。
【００５６】
工程−３ｅ
不図示のヒーターを用いて真空容器全体並びに電子放出素子を一旦２５０℃に１０時間加熱し更に排気を継続することで、その後の室温時における真空容器内圧力を１×１０^-7Ｐａ程度まで低下させた。
【００５７】
以上のように、真空容器内圧力を調整した後、素子Ａ〜Ｄの４素子について、本発明の駆動方法の特徴である予備駆動を行った。
予備駆動は、アノード電圧を０Ｖとし、素子電極２に電圧を印加して行った。印加した電圧は図１０（ｂ）に示すようなパルス電圧であり、Ｖf1 ＝１５Ｖ、パルス幅Ｔ1 は１ｍsec 、Ｖf12＝１４．８Ｖ、パルス幅Ｔ12＝０．１ｍsec 、パルス間隔Ｔ2 は１６．７ｍsec として、
【００５８】
【数５】

の値の変化率を見ながら行った。１分間予備駆動を行ったところ、上記Ｓの値の変化率が５％以内となったので、予備駆動を終了した。
【００５９】
次に、予備駆動を行ったそれぞれの電子放出素子について、Ｉf −Ｖf 特性を測定した。素子電極２に電圧を１５Ｖから１２Ｖまで０．１Ｖ刻みで印加し、その時素子に流れる素子電流Ｉf を測定した。
測定したＩf −Ｖf 特性より、素子電圧１５Ｖにおける素子電流Ｉf1に対して、素子電流Ｉf2が、それぞれ０．８Ｉf1、０．７Ｉf1、０．５Ｉf1及び０．３Ｉf1となる駆動電圧を求め、素子Ａ〜Ｄの駆動電圧をそれぞれ表１のように決めた。また、比較のために素子Ｅは予備駆動を行わずに１５Ｖの一定電圧で駆動を行った。
【００６０】
素子Ａ〜Ｅについて、それぞれの駆動電圧を印加し、アノード電極に１ｋＶの高圧を印加して放出電流を測定したところ、良好な放出電流が得られた。
また、素子Ａ〜Ｅについて、それぞれの駆動電圧を印加し、アノード電極に１ｋＶの高圧を印加して素子を長時間駆動した。駆動時の放出電流の経時変化は、予備駆動を行わなかった素子Ｅが最も大きく、次いで素子Ａの経時変化が大きかった。素子Ｂ、Ｃ、Ｄに関しては放出電流の減少と変動が少なく、長時間にわたって安定な電子放出特性が得られた。
【００６１】
【表１】

【００６２】
（実施例２）
実施例１と同様にして複数個の電子放出素子を作成し、作成した電子放出素子について予備駆動を行った。
予備駆動は、アノード電圧を０Ｖとし、素子電極２に電圧を印加して行った。印加した電圧は図１０（ａ）に示すようなパルス電圧であり、パルス幅Ｔ1 は０．５ｍsec 、パルス幅Ｔ12＝０．１ｍsec 、パルス間隔Ｔ2 は１６．７ｍsec とした。電圧Ｖf1 は素子ごとに１４Ｖ〜１６Ｖの範囲で０．１Ｖ刻みに変えて行い、それぞれの場合において、電圧Ｖf12は０．９Ｖf1 とし、
【００６３】
【数６】

の値の変化率を見ながら行い、それぞれ上記Ｓの値の変化率が５％以内となったところで予備駆動を終了した。
【００６４】
次に、予備駆動を行った各電子放出素子についてＩf −Ｖf 特性を測定した。素子電極２に電圧を１６Ｖから１２Ｖまで０．１Ｖ刻みで印加し、その時素子に流れる素子電流Ｉf を測定した。
測定したＩf −Ｖf 特性より、駆動電圧を１４Ｖとした時の素子電流Ｉf2が、予備駆動電圧における素子電流Ｉf1に対して、それぞれ０．８Ｉf1、０．７Ｉf1、０．５Ｉf1及び０．３Ｉf1となる予備駆動電圧を求め、素子Ｆ、Ｇ、Ｈ、Ｉの予備駆動電圧をそれぞれ表２のように決め、上記予備駆動と同様の方法で予備駆動を行った。また、比較のために素子Ｊは予備駆動を行わず、１４Ｖで駆動を行った。
【００６５】
素子Ｆ〜Ｊについて、１４Ｖの駆動電圧を印加し、アノード電極に１ｋＶの高圧を印加して放出電流を測定したところ、いずれの素子も良好な放出電流が得られた。
また、素子Ｆ〜Ｊについて、それぞれ１４Ｖの駆動電圧を印加し、アノード電極に１ｋＶの高圧を印加して素子を長時間駆動した。駆動時の放出電流の経時変化は、予備駆動を行わなかった素子Ｊが最も大きく、次いで素子Ｆの経時変化が大きかった。素子Ｇ、Ｈ、Ｉに関しては放出電流の減少と変動が少なく、長時間安定な電子放出特性が得られた。
【００６６】
【表２】

【００６７】
（実施例３）
実施例１と同様にして複数個の電子放出素子（素子Ｋ、Ｌ、Ｍ、Ｎ）を作成し、作成した電子放出素子について、実施例１と同じ１５Ｖで予備駆動を行った。
予備駆動は、アノード電圧を０Ｖとし、素子電極２に電圧を印加して行った。印加した電圧は図１０（ｂ）に示すようなパルス電圧であり、Ｖf1 ＝１５Ｖ、パルス幅Ｔ1 は０．２ｍsec 、Ｖf12＝１４．８Ｖ、パルス幅Ｔ12＝０．１ｍsec
、パルス間隔Ｔ2 は１６．７ｍsec として、
【００６８】
【数７】

の値の変化率を見ながら行った。
【００６９】
予備駆動は、素子Ｋについては上記Ｓの値の変化率が約１０％になるまで行い、素子Ｌについては上記Ｓの値の変化率が約７％になるまで行い、素子Ｍについては上記Ｓの値の変化率が約５％になるまで行い、素子Ｎについては上記Ｓの値の変化率が約３％になるまで行った。
【００７０】
次に、予備駆動を行った各電子放出素子について、１４．２Ｖの駆動電圧を印加し、アノード電極に１ｋＶの高圧を印加して素子を長時間駆動した。駆動時の放出電流の経時変化は、素子Ｋが最も大きく、次いで素子Ｌの経時変化が大きかった。素子Ｍ、Ｎに関しては放出電流の減少と変動が少なく、長時間にわたって安定な電子放出特性が得られた。
【００７１】
【発明の効果】
以上、本発明の駆動方法によれば、駆動時における電子放出部の熱的な劣化を抑え、長時間にわたって安定した放出電流を得ることができる。また、本発明の製造方法によれば、放出電流が長時間にわたって安定な、すなわち画像形成装置に用いて長時間にわたり画像表示に好適な明るさやコントラストを維持することが可能な電子放出素子を得ることができる。
【図面の簡単な説明】
【図１】 本発明に関わる電子放出素子についての、放出電流Ｉe 及び素子電流Ｉf と素子電圧Ｖf の関係の一例を示すグラフである。
【図２】 本発明に関わる電子放出素子についての、放出電流Ｉe 及び素子電流Ｉf と素子電圧Ｖf の関係の一例を示すグラフである。
【図３】 本発明に関わる平面型電子放出素子の模式図である。
【図４】 本発明に関わる垂直型電子放出素子の模式図である。
【図５】 本発明の電子放出素子の製造方法を示す模式図である。
【図６】 本発明に適用可能な測定系を備えた真空装置を示す模式図である。
【図７】 本発明の電子源の製造方法において採用できる電圧波形の一例を示す模式図である。
【図８】 本発明の電子源の製造方法において採用できる電圧波形の一例を示す模式図である。
【図９】 本発明に関わる電子放出素子についての、素子電流Ｉf と素子電圧Ｖf の関係の一例を示すグラフである。
【図１０】 本発明の電子源の製造方法において採用できる電圧波形の一例を示す模式図である。
【符号の説明】
１：基板、２，３：素子電極、４：導電性薄膜、５：電子放出部、６：段差形成部、６１：真空容器、６２：電源、６３：素子電流Ｉf を測定する電流計、６４：アノード電極、６５：高圧電源、６６：放出電流Ｉe を測定するための電流計、６７：排気装置、６８：活性化物質収容容器。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a driving method and a manufacturing method of an electron-emitting device.
[0002]
[Prior art]
Conventionally, two types of electron-emitting devices are known: a thermionic source and a cold cathode electron source. Cold cathode electron sources include field emission type (hereinafter abbreviated as FE type), metal / insulating layer / metal type (hereinafter abbreviated as MIM type), surface conduction electron-emitting devices, and the like.
[0003]
Examples of FE types include WP Dyke & WW Dolan, "Field emission", Advance in Electron Physics, 8, 89 (1956) or CA Spindt, "Physical Properties of thin-film field emission cathodes with molybdenum cones", J. Appl. Phys., 47, 5248 (1976) etc. are known.
An example of the MIM type is disclosed in C. A. Mead, “Operation of Tunnel-Emission Devices”, J. Apply. Phys., 32, 646 (1961), and the like.
Examples of surface conduction electron-emitting devices include those disclosed in M. I. Elinson, Radio Eng. Electron Phys., 10, 1290, (1965).
[0004]
A surface conduction electron-emitting device utilizes a phenomenon in which electron emission occurs when a current is applied in parallel to a film surface of a small-area thin film formed on a substrate. As this surface conduction electron-emitting device, SnOl by Erinson et al.₂ Thin film, Au thin film [G. Dittmer, Thin Solid Films, 9, 317 (1972)], In₂ O_Three / SnO₂ By thin film [M. Hartwell and CG Fonstad, IEEE Trans. ED Conf., 519 (1975)], by carbon thin film [Hiraki Araki et al .: Vacuum, Vol. 26, No. 1, p. 22 (1983)], etc. Has been reported.
[0005]
The present applicant has made a number of proposals regarding a surface conduction electron-emitting device having a novel structure and its application. The basic configuration, manufacturing method, and the like are disclosed in, for example, JP-A-7-235255 and JP-A-7-235275. The main points will be briefly described below.
[0006]
The surface conduction electron-emitting device includes a pair of device electrodes 2 and 3 opposed to each other on a substrate 1 as schematically shown in a top view (a) and a cross-sectional view (b) of FIG. And an electroconductive thin film 4 having an electron emission portion 5 in a part thereof. The electron emission portion 5 is a portion in which a part of the conductive thin film 4 is broken, deformed, or altered and becomes high resistance. In addition, a deposited film containing carbon or a carbon compound as a main component may be formed around the electron emitting portion 5 and its periphery.
The electron-emitting device can emit electrons from the electron-emitting portion 5 by applying a voltage between the device electrodes 2 and 3.
[0007]
Since such an electron-emitting device has a simple configuration and is easy to manufacture, a large number of electron-emitting devices can be formed over a large area. Therefore, a large-area electron source can be formed by forming a plurality of electron-emitting devices on a substrate and electrically connecting each electron emission by wiring. Further, an image forming apparatus can be formed by combining the electron source and the image forming member.
[0008]
[Problems to be solved by the invention]
Incidentally, an image forming apparatus formed using the above-described electron-emitting device is required to maintain brightness and contrast suitable for image display for a long time. In order to realize this, the electron-emitting device is required to suppress a decrease in the amount of electrons emitted from the electron-emitting device and emit a certain amount or more of electrons in an expected period.
[0009]
However, the above-described electron-emitting device has a problem that the amount of emission current gradually decreases when driven for a long time with the same driving voltage. This is presumably because the temperature of the electron emission part rises due to the element current flowing in the electron emission part when the electron emission element is driven, and the electron emission part is deteriorated by heat.
[0010]
An object of the present invention is to solve the aforementioned problems. That is, a stable driving method of an electron-emitting device for suppressing a decrease in the amount of emitted electrons over time and maintaining a constant amount of emitted electrons over a long period of time, and electron emission capable of maintaining a constant amount of emitted electrons over a long period of time The object is to provide a method for manufacturing an element.
[0011]
[Means for Solving the Problems]
  In order to achieve the above object, a driving method of the present invention is provided on a substrate.Been formedA pair of opposing device electrodes;TheConductive thin film including electron emission portion formed between device electrodesWhenElectron emitting device comprisingOf the aboveBetween element electrodesVoltageVf1TheApplied (hereinafter referred to as preliminary drive)Current I between the device electrodes f1 The process of flowingAfterIn,SaidVoltage Vf2 at which current If2 satisfies If2 ≦ 0.7If1 with respect to current If1Is applied between the device electrodesDriveDriving the electron-emitting device, the current I between the device electrodes f1 The process of flowing f11 | ≦ | V f1 Voltage V that is | f11 And the voltage V f11 Voltage V whose absolute value is smaller than f12 Is applied between the element electrodes, thereby the voltage V f11 And the voltage V f12 Current I flowing between the element electrodes corresponding to each of f11 And I f12 From
    S = {log ( I f12 / V f12 ² ) − log ( I f11 / V f11 ² )} / (1 / V f12 -1 / V f11 )
Until the rate of change of the value of S becomes 5% or less, f1 Is applied between the device electrodes..
[0012]
  The manufacturing method of the present invention is formed on a substrate.TheA pair of opposing device electrodes;TheIt consists of a conductive thin film including an electron emission portion formed between element electrodes,SaidBetween element electrodesInVoltage Vf2Current I between the element electrodes f2 ShedA method of manufacturing an electron-emitting device driven by the electron-emitting device, the electron-emitting portionTheFormationShiAfterAnd the voltage V f2 Higher voltage V f1 A voltage application step of applying a voltage between the element electrodes.ProcessIs,｜ V f11 | ≦ | V f1 Voltage V that is | f11 And the voltage V f11 Voltage V whose absolute value is smaller than f12 Is applied between the element electrodes, thereby the voltage V f11 And said V f12 Current I flowing between the element electrodes corresponding to each of f11 And I f12 From
[0014]
[Equation 3]

Until the rate of change of the value of S is 5% or less, The voltage V f1 Is applied between the device electrodes, and the current I flowing between the device electrodes immediately before the voltage application step is completed. f1 And the current I f2 Relationship with I f2 ≦ 0.7I f1 The voltage V in the voltage application step f1 It is characterized by setting.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
The preferred embodiment of the present invention and the operation of the present invention will be described below.
The basic configuration of the surface conduction electron-emitting device to which the present invention can be applied is roughly divided into two types, a planar type and a vertical type.
First, a planar surface conduction electron-emitting device will be described.
3A and 3B are schematic views showing the configuration of a planar surface conduction electron-emitting device to which the present invention can be applied. FIG. 3A is a plan view and FIG. 3B is a cross-sectional view. In FIG. 3, 1 is a substrate, 2 and 3 are element electrodes, 4 is a conductive thin film, and 5 is an electron emission portion.
[0016]
As the substrate 1, quartz glass, glass with reduced impurity content such as Na, blue plate glass, SiO plate formed on a blue plate glass by sputtering or the like.₂ A glass substrate laminated with ceramics, ceramics such as alumina, and a Si substrate can be used.
A general conductive material can be used as the material of the opposing device electrodes 2 and 3. For example, Ni, Cr, Au, Mo, W, Pt, Ti, Al, Cu, Pd and other metals or alloys and Pd, Ag, Au, RuO₂ , Printed conductors composed of metals such as Pd-Ag or metal oxides and glass, In₂ O_Three -SnO₂ It can be appropriately selected from transparent conductors such as semiconductor conductive materials such as polysilicon.
[0017]
The element electrode interval L, the element electrode length W, the shape of the conductive thin film 4 and the like are designed in consideration of the applied form and the like. The element electrode interval L can be preferably in the range of several hundreds of nanometers to several hundreds of micrometers, and more preferably in the range of several micrometers to several tens of micrometers.
The element electrode length W can be in the range of several μm to several hundred μm in consideration of the resistance value of the electrode and electron emission characteristics. The film thickness d of the device electrodes 2 and 3 can be in the range of several tens of nm to several μm.
Not only the configuration shown in FIG. 3 but also a configuration in which the conductive thin film 4 and the opposing element electrodes 2 and 3 are laminated on the substrate 1 in this order may be employed.
[0018]
The conductive thin film 4 is preferably a fine particle film composed of fine particles in order to obtain good electron emission characteristics. The film thickness is appropriately set in consideration of the step coverage to the device electrodes 2 and 3, the resistance value between the device electrodes 2 and 3, forming conditions described later, and the like, but usually several hundred pm to several hundred nm. Is preferable, and more preferably, the range is from 1 nm to 50 nm. Its resistance value is 10 for Rs.² To 10⁷ It is the value of Ω / □. Rs is an amount that appears when the resistance R of a thin film having a thickness of t, a width of w, and a length of l is set as R = Rs (l / w). In this specification, the forming process is described by taking an energization process as an example, but the forming process is not limited to this, and includes a process of forming a high resistance state by causing a crack in the film. It is.
[0019]
The material constituting the conductive thin film 4 is a metal such as Pd, Pt, Ru, Ag, Au, Ti, In, Cu, Cr, Fe, Zn, Sn, Ta, W, Pd, PdO, SnO.₂ , In₂ O_Three , PbO, Sb₂ O_Three Oxides such as HfB₂ , ZrB₂ , LaB₆ , CeB₆ , YB_Four , GdB_Four Boride such as TiC, ZrC, HfC, Ta, C, SiC, WC, and the like, TiN, ZrN, HfN, nitride, Si, Ge, etc., carbon, etc.
[0020]
The fine particle film described here is a film in which a plurality of fine particles are aggregated, and the fine structure thereof is a state in which the fine particles are individually dispersed and arranged, or a state in which the fine particles are adjacent to each other or overlap each other (some fine particles are aggregated, Including the case where an island-like structure is formed as a whole). The particle diameter of the fine particles is in the range of several times 0.1 nm to several hundred nm, preferably in the range of 1 nm to 20 nm.
[0021]
The electron emission portion 5 is constituted by a high-resistance crack formed in a part of the conductive thin film 4, and depends on the film thickness, film quality, material, and a method such as energization forming described later. Become. Inside the electron emission portion 5, there may be conductive fine particles having a particle size in the range of several times 0.1 nm to several tens of nm. The conductive fine particles contain part or all of the elements of the material constituting the conductive thin film 4. The electron emitting portion 5 and the conductive thin film 4 in the vicinity thereof can also contain carbon and a carbon compound.
[0022]
Next, a vertical surface conduction electron-emitting device will be described.
FIG. 4 is a schematic view showing an example of a vertical surface conduction electron-emitting device to which the surface conduction electron-emitting device of the present invention can be applied.
4, the same parts as those shown in FIGS. 3A and 3B are denoted by the same reference numerals as those shown in FIGS. 3A and 3B. 6 is a step forming portion. The substrate 1, the device electrodes 2 and 3, the conductive thin film 4, and the electron emission portion 5 can be made of the same material as that of the above-described planar surface conduction electron emission device. The step forming portion 6 is made of SiO formed by vacuum deposition, printing, sputtering, or the like.₂ It can comprise with insulating materials, such as. The film thickness of the step forming portion 6 corresponds to the element electrode interval L of the planar surface conduction electron-emitting device described above, and can be in the range of several hundred nm to several tens of μm. This film thickness is set in consideration of the manufacturing method of the step forming portion and the voltage applied between the device electrodes, but is preferably in the range of several tens of nm to several μm.
[0023]
The conductive thin film 4 is laminated on the device electrodes 2 and 3 after the device electrodes 2 and 3 and the step forming portion 6 are formed. In FIG. 4, although the electron emission part 5 is formed in the level | step difference formation part 6, it depends on preparation conditions, forming conditions, etc., and a shape and a position are not restricted to this.
[0024]
There are various methods for manufacturing the surface conduction electron-emitting device described above, and an example is schematically shown in FIG.
Hereinafter, an example of the manufacturing method will be described with reference to FIGS. In FIG. 5 as well, the same parts as those shown in FIG.
1) The substrate 1 is sufficiently washed with a detergent, pure water, an organic solvent, etc., and an element electrode material is deposited by a vacuum deposition method, a sputtering method, etc. 3 are formed (FIG. 5A).
2) An organometallic solution is applied to the substrate 1 provided with the device electrodes 2 and 3 to form an organometallic thin film. As the organometallic solution, a solution of an organometallic compound containing the metal of the material of the conductive film 4 as a main element can be used. The organic metal thin film is heated and baked and patterned by, for example, a lift-off method using a mask corresponding to the shape of the conductive thin film, etching, or the like to form the conductive thin film 4 (FIG. 5B). Here, the application method of the organic metal solution has been described, but the method of forming the conductive thin film 4 is not limited to this, and a vacuum deposition method, a sputtering method, a chemical vapor deposition method, a dispersion coating method, A dipping method, a spinner method, or the like can also be used, and direct patterning can also be performed by an inkjet method or the like.
[0025]
3) Subsequently, a forming process is performed.
The electrical processing after the forming step can be performed in a vacuum vessel equipped with a measurement system as shown in FIG.
In FIG. 6, 61 is a vacuum vessel, 62 is a power source for applying an element voltage to the element, 63 is an ammeter for measuring the element current If flowing through the conductive thin film 4 between the element electrodes 2 and 3, and 64 is An anode electrode for capturing the emission current Ie emitted from the electron emitter 5, 65 is a high voltage power source for applying a voltage to the anode electrode, 66 is an ammeter for measuring the emission current Ie, and 67 is a vacuum vessel An exhaust device 68 for exhausting the interior of the device 61 is an activated substance container.
[0026]
After the substrate 1 is placed in the vacuum vessel 61 and the inside of the vacuum vessel is evacuated, when a voltage is applied between the device electrodes 2 and 3, the electron emission portion 5 having a changed structure is formed in the conductive thin film 4. (FIG. 5C). According to the energization forming, a region having a structural change such as local destruction, deformation or alteration is formed in the conductive thin film 4. This part constitutes the electron emission part 5. An example of the voltage waveform of energization forming is shown in FIG.
The voltage waveform is preferably a pulse waveform. This is shown in FIG. 7A in which a voltage pulse is applied while increasing the pulse peak value, and in FIG. 7B in which a pulse having a constant pulse peak value is applied. There is a technique.
[0027]
T1 and T2 in FIG. 7A are the pulse width and pulse interval of the voltage waveform. Usually, T1 is set in the range of 1 μsec to 10 msec, and T2 is set in the range of 10 μsec to 10 msec. The peak value of the pulse can be increased by about 0.1 V step, for example. The end of the energization forming process can be determined by, for example, reading a change in resistance value caused by local destruction and deformation of the conductive thin film 4, and as an example, during the pulse interval T2, the conductive thin film 4 can be determined. Can be detected by applying a voltage that does not cause local destruction or deformation and measuring the current. For example, the element current that flows when a voltage of about 0.1 V is applied is measured, the resistance value is obtained, and when a resistance of 1 MΩ or more is indicated, the energization forming is terminated. The pulse waveform is not limited to a rectangular wave, and a desired waveform such as a triangular wave can be adopted.
[0028]
T1 and T2 in FIG. 7B can be the same as those shown in FIG. The peak value of the pulse is appropriately selected according to the form of the surface conduction electron-emitting element. Under such conditions, for example, a voltage is applied for several seconds to several tens of minutes. The pulse waveform is not limited to a rectangular wave, and a desired waveform such as a triangular wave can be adopted.
[0029]
4) It is preferable to perform a process called an activation process on the element after forming. The activation process is a process in which the device current If and the emission current Ie are remarkably changed by this process.
The activation step can be performed, for example, by repeating application of a pulse voltage in an atmosphere containing an organic substance gas, similarly to energization forming. As the pulse voltage, the bipolar voltage pulse shown in FIG. 8 can be used in addition to the voltage pulse shown in FIG.
[0030]
The activation atmosphere can be formed by using organic gas remaining in the atmosphere when the vacuum vessel 61 is evacuated using, for example, an oil diffusion pump or a rotary pump. It can also be obtained by introducing an appropriate organic substance gas from the activated substance container 68 into the evacuated vacuum. A preferable gas pressure of the organic material at this time is appropriately set according to the case because it varies depending on the application form, the shape of the vacuum container, the kind of the organic material, and the like. Examples of suitable organic substances include alkanes, alkenes, alkyne aliphatic hydrocarbons, aromatic hydrocarbons, alcohols, aldehydes, ketones, amines, organic acids such as phenol, carvone, and sulfonic acid. Specifically, saturated hydrocarbons such as methane, ethane, and propane, unsaturated hydrocarbons such as ethylene and propylene, butadiene, n-hexane, l-hexene, benzene, toluene, O-xylene, and benzonitrile. , Tolunitrile, chloroethylene, trichloroethylene, methanol, ethanol, isopropanol, formaldehyde, acetaldehyde, acetone, methyl ethyl ketone, diethyl ketone, methylamine, ethylamine, acetic acid, propionic acid, or a mixture thereof can be used. By this treatment, carbon or a carbon compound is deposited on the device from an organic substance present in the atmosphere, and the device current If and the emission current Ie are remarkably changed.
[0031]
The end of the activation process is determined appropriately while measuring the device current If and the emission current Ie. The pulse width, pulse interval, pulse peak value, etc. are set as appropriate.
[0032]
5) The electron-emitting device obtained through such steps is preferably subjected to a stabilization step. This process removes the organic material adsorbed on the surface of the electron-emitting device and the organic material in the vacuum container containing the electron-emitting device, and the above-described carbon and carbon compounds are newly added even if the electron-emitting device is driven. This is a process for preventing deposition. As the vacuum exhaust device for exhausting the vacuum vessel, it is preferable to use a device that does not use oil so that an organic substance such as oil generated from the device does not affect the characteristics of the element. Specifically, vacuum evacuation devices such as a magnetic levitation turbo molecular pump, a cryopump, a sorption pump, and an ion pump can be given.
[0033]
The partial pressure of the organic component in the vacuum vessel is 1 × 10 with a partial pressure at which the above-described carbon and carbon compounds are not newly deposited.^-6Pa or less is preferable, and further 1 × 10^-8Pa or less is particularly preferable. Furthermore, when evacuating the inside of the vacuum vessel, it is preferable to heat the entire vacuum vessel so that the organic substance molecules adsorbed on the inner wall of the vacuum vessel and the electron-emitting device can be easily evacuated. The heating conditions at this time are 80 to 250 ° C., preferably 150 ° C. or higher, and it is desirable to perform the treatment for as long as possible. However, the heating conditions are not particularly limited, and the size and shape of the vacuum vessel, the configuration of the electron-emitting device, etc. The conditions are appropriately selected according to these conditions. The pressure in the vacuum vessel needs to be as low as possible, 1 × 10^-FivePa or less is preferable, and further 1 × 10^-6Pa or less is particularly preferable.
[0034]
The driving atmosphere after the stabilization process is preferably maintained at the end of the stabilization process. However, the present invention is not limited to this. If the organic substance is sufficiently removed, the vacuum vessel Even if the pressure increases slightly, stable characteristics can be maintained to some extent.
By adopting such a vacuum atmosphere, deposition of new carbon or carbon compounds can be suppressed, and H adsorbed on a vacuum vessel or a substrate can be suppressed.₂O or O₂ As a result, the device current If and the emission current Ie are relatively stable.
[0035]
The basic characteristics of the electron-emitting device obtained through the above-described steps will be described.
First, a typical example of the operating characteristics of the electron-emitting device is schematically shown in FIG.
FIG. 1 is a diagram schematically showing a relationship between a current (element current) If flowing through an element and an electric current (emitted current) Ie emitted from an electron emitting portion with respect to an element voltage Vf applied to the element. Since the value of Ie is extremely small compared with If, it is shown in arbitrary scales. However, all scales are linear scales.
[0036]
For measuring the device current If and the emission current Ie, the vacuum apparatus shown in FIG. 6 can be used. For example, the voltage of the anode electrode is in the range of 1 kV to 10 kV, and the distance H between the anode electrode 64 and the electron-emitting device. Can be measured in a range of 2 mm to 8 mm.
[0037]
As is apparent from FIG. 1, the surface conduction electron-emitting device to which the present invention can be applied has the following three characteristic properties with respect to the emission current Ie.
That is,
(I) When an element voltage higher than a certain voltage (referred to as a threshold voltage, Vth in FIG. 1) is applied to this element, the emission current Ie increases abruptly, while the emission current Ie decreases below the threshold voltage Vth. Almost no detection. That is, it is a non-linear element having a clear threshold voltage Vth for the emission current Ie.
(Ii) Since the emission current Ie monotonically increases with the device voltage Vf, the emission current Ie can be controlled by the device voltage Vf.
(Iii) The emitted charge captured by the anode electrode depends on the time during which the device voltage Vf is applied. That is, the amount of charge trapped by the anode electrode can be controlled by the time during which the device voltage Vf is applied.
[0038]
Although FIG. 1 shows a case where If has a threshold value for Vf and If increases monotonously with respect to Vth equal to or higher than the threshold value (MI characteristic), If also has a threshold value for Vf depending on the manufacturing process and measurement conditions. There is also a case where a controlled negative resistance is exhibited (VCNR characteristic). When the VCNR characteristic is shown, the If-Vf characteristic is not stable. In this case, Ie shows the MI characteristic, but it is still not stable. Also in this case, a stable MI characteristic can be exhibited by performing the stabilization process.
[0039]
In the electron-emitting device subjected to the stabilization process, the device current If and the emission current Ie have MI characteristics with respect to the device voltage Vf, and the device current If and the emission current Ie are uniquely determined with respect to the device voltage Vf. Has characteristics. Further, the present inventors have found that the If-Vf characteristic and the Ie-Vf characteristic at this time depend on the maximum voltage Vmax applied after the stabilization process.
[0040]
The IV characteristics of this electron-emitting device will be described with reference to FIGS. 2A is a diagram showing the relationship between If and Vf, and FIG. 2B is a diagram showing the relationship between Ie and Vf.
2A and 2B, the solid line indicates the IV characteristics of the element driven at the maximum voltage Vmax = Vmax1. When this element is driven with an element voltage of Vmax1 or less, it has the same IV characteristic as the IV characteristic indicated by the solid line. However, when driven with a voltage Vmax2 equal to or higher than Vmax1, the element exhibits different IV characteristics as indicated by a broken line in the figure. When this element is driven with an element voltage equal to or lower than Vmax2, this element is indicated by the broken line. It has the same IV characteristic as the IV characteristic. This is presumably because the shape of the electron emission portion, the electron emission area, and the like change depending on the maximum voltage Vmax applied to the electron emission element.
[0041]
In the driving method of the present invention, when driving the electron-emitting device after the stabilization process, the device is first driven at a voltage of the device voltage Vf1 (hereinafter, this driving is referred to as “preliminary driving”). As a result, the electron-emitting device has If-Vf characteristics and Ie-Vf characteristics that are uniquely determined by the voltage Vmax = Vf1, as shown in FIG.
Next, if the element current at the element voltage Vf1 at the end of the preliminary driving is If1, and if-Vf characteristics determined by the preliminary driving, Vf2 satisfying If2 ≦ 0.7If1 is selected as the driving voltage (in FIG. 1). Vf2).
[0042]
Even if the drive voltage Vf2 satisfying If2 ≦ 0.7If1 is applied to the element preliminarily driven at the element voltage Vf1, it is considered that the shape of the electron emission portion and the emission area hardly change. During driving, the element is driven at a lower device current If than that during preliminary driving while having substantially the same emission area as that during preliminary driving. Therefore, it is considered that the current density of the device current flowing in the electron emission portion during driving can be reduced, thermal deterioration of the electron emission portion can be suppressed, and electrons can be stably emitted for a long time.
[0043]
The time during which a stable emission current can be obtained tends to change almost exponentially with respect to the ratio of If difference between the pre-driving and the driving (If1-If2) / If1. In the above-described device, although depending on the manufacturing conditions of the device, etc., every time the driving If is reduced by 10% with respect to If1, the time for obtaining a stable emission current becomes about 5 to 10 times longer. Therefore, by driving at a voltage satisfying If2 ≦ 0.7If1, the time for obtaining a stable emission current can be increased by approximately two orders of magnitude compared to the case of driving at a constant voltage, and the stability is greatly improved. Can be improved.
[0044]
The pre-driving may be performed for a time required to keep the If-Vf characteristics and the Ie-Vf characteristics of the electron-emitting device unchanged when driving at a voltage lower than the pre-driving voltage after the pre-driving. It can be performed by applying a pulse voltage of μsec to several tens of msec, preferably 10 μsec to 10 msec, of several pulses to several tens of pulses or more.
[0045]
For example, the time required for preliminary driving can be determined by the following method. The If-Vf characteristic of the electron-emitting device produced by the above-described process is expressed as log (If / Vf with respect to 1 / Vf.²) Is plotted (Fowler-Nordheim Plots), a substantially linear relationship is obtained as shown in FIG.
[0046]
Therefore, at the time of the preliminary driving, a voltage Vf11 satisfying | Vf11 | ≦ | Vf1 | and a voltage Vf12 having a small absolute value dV smaller than Vf11 are continuously applied (for example, Vf11 = Vf1, Vf12 = Vf1−dV), From the currents If11 and If12 that flow when each voltage is applied, the slope S in FIG.
[0047]
[Expression 4]

And the change in the value of the slope S can be seen to see the change in the If-Vf characteristic of the electron-emitting device. According to the experiments by the present inventors, if the preliminary drive is performed for a time until the rate of change of the value of the slope S becomes 5% or less, the value of the slope S becomes substantially constant in the subsequent drive. The effect is seen. Therefore, it is sufficient to perform preliminary driving for a time until the change rate of the value of the slope S becomes 5% or less.
[0048]
As voltage waveforms in the preliminary drive, voltage waveforms as shown in FIGS. 10A, 10B, and 10C can be used. FIG. 10A shows a voltage waveform in which the voltage changes over time T12 to voltage Vf12 immediately after the preliminary drive voltage Vf1 is applied for time T1. FIG. 10B shows a voltage waveform in which the voltage Vf12 is applied for the time T12 immediately after the preliminary drive voltage Vf1 is applied for the time T1. FIG. 10C shows a voltage waveform in which the voltage Vf12 is applied for T12 time after the preliminary driving voltage Vf1 is applied for T1 time. The change rate of the slope S can be obtained from the element current If1 (If11 = If1 here) and If12 flowing when each voltage (here, Vf11 = Vf1) is applied, and the time required for the preliminary drive can be obtained.
[0049]
This preliminary driving is usually performed at the final stage of the manufacturing process, for example, after the stabilization process or as a part of the stabilization process, but as a refresh process before shipment after inventory or after the start of use of the electron-emitting device. It is also possible to perform as an appropriate refresh mode.
[0050]
【Example】
Hereinafter, the present invention will be described in more detail with reference to examples.
Example 1
In this embodiment, the driving method of the present invention is applied to an electron-emitting device having the same configuration as that schematically shown in FIG. Based on FIG. 5, the manufacturing method of the electron-emitting device used in the present embodiment will be described.
[0051]
First, five electron-emitting devices of devices A to E were formed on the substrate 1 by the steps -a to -e.
Step-a ((a) of FIG. 5)
After cleaning the substrate 1 made of a quartz substrate, 5 nm of Ti and 50 nm of Pt were deposited on the substrate 1 by sputtering. Thereafter, a photoresist is applied on the deposited film to form a pattern having a shape corresponding to the device electrode pairs 2 and 3, and then unnecessary portions of Pt and Ti are removed by etching, and then the resist is removed to remove the substrate. Element electrodes 2 and 3 were formed on 1. The distance L between the device electrodes 2 and 3 was 10 μm, and the length W of the device electrode was 300 μm.
[0052]
Step-b ((b) of FIG. 5)
On the substrate 1 provided with the device electrodes 2 and 3, Cr having a thickness of 50 nm is deposited by vacuum deposition, and an opening corresponding to a position where a conductive thin film is formed on the Cr film by using a photolithography technique is formed. Form. Thereafter, a solution of an organic Pd compound (ccp-4230: manufactured by Okuno Pharmaceutical Co., Ltd.) was applied and subjected to a heat treatment at 300 ° C. in the atmosphere. Next, the Cr film was removed by wet etching, washed with pure water and dried to form the conductive thin film 4.
[0053]
The subsequent steps were performed after the electron-emitting devices in the manufacturing process were placed in a vacuum container as shown in FIG. 6 and electrically connected. As shown in FIG. 6, the device electrode 3 is connected to the ground potential, and the device electrode 2 is connected to the ammeter 63 and the device voltage power source 62 through a current introduction terminal. Further, an anode electrode is disposed 5 mm above the substrate 1, and the anode electrode 64 is connected to an ammeter 66 and a high voltage power source 65 through a current introduction terminal.
[0054]
Step-3c
The inside of the vacuum vessel is 1 × 10 using a scroll pump and a turbo molecular pump.^-3After evacuating to about Pa or less, a voltage generated by an element voltage power source was applied to the element electrode 2 and subjected to forming treatment to form the electron emission portion 5. The applied voltage is a pulse voltage as shown in FIG. 7A, and is a pulse whose peak value gradually increases as time passes. The pulse width T1 was 1 msec and the pulse interval T2 was 16.7 msec. During the forming process, when the pulse peak value reached 6V, the current value flowing through the ammeter decreased dramatically. After that, after applying the pulse voltage until the pulse peak value became 6.5 V, the voltage application was stopped, and the resistance value between the device electrodes 2 and 3 was measured. Ended.
[0055]
Step-3d
Further evacuation of the vacuum vessel was continued, and the pressure inside the vessel was 10^-FiveAfter decreasing to Pa or lower, an activation process was performed by introducing benzonitrile gas into the vacuum vessel. In the activation step, the pressure in the vacuum vessel into which the activation gas is introduced is 1.3 × 10^-FourThe voltage was adjusted to Pa, and the voltage generated by the element voltage power source was applied to the element electrode 2. The applied voltage is a bipolar pulse voltage as shown in FIG. 8, and is a pulse having a constant peak value. The pulse peak value was 16 V, the pulse width T1 was 1 msec, and the pulse interval T2 was 20 msec. The activation treatment was performed for 1 hour, and then the voltage application was stopped, the introduction of the activation gas was stopped, and the activation gas was exhausted from the vacuum vessel.
[0056]
Step-3e
The whole vacuum vessel and the electron-emitting device are once heated to 250 ° C. for 10 hours using a heater (not shown), and further evacuation is continued.^-7The pressure was reduced to about Pa.
[0057]
As described above, after adjusting the pressure inside the vacuum vessel, preliminary driving, which is a feature of the driving method of the present invention, was performed on the four elements A to D.
The preliminary driving was performed by setting the anode voltage to 0 V and applying a voltage to the device electrode 2. The applied voltage is a pulse voltage as shown in FIG. 10B, and Vf1 = 15V, pulse width T1 is 1 msec, Vf12 = 14.8V, pulse width T12 = 0.1 msec, and pulse interval T2 is 16.7 msec. ,
[0058]
[Equation 5]

We went while looking at the rate of change of the value. When preliminary driving was performed for 1 minute, the change rate of the value of S was within 5%, so the preliminary driving was terminated.
[0059]
Next, the If-Vf characteristic was measured for each electron-emitting device that was preliminarily driven. A voltage was applied to the device electrode 2 from 15 V to 12 V in increments of 0.1 V, and the device current If flowing at that time was measured.
From the measured If-Vf characteristics, the drive voltages at which the device current If2 becomes 0.8If1, 0.7If1, 0.5If1, and 0.3If1, respectively, are obtained with respect to the device current If1 at the device voltage 15V. The driving voltage of D was determined as shown in Table 1. For comparison, the element E was driven at a constant voltage of 15 V without performing preliminary driving.
[0060]
With respect to the devices A to E, when the respective drive voltages were applied and a high voltage of 1 kV was applied to the anode electrode and the emission current was measured, a good emission current was obtained.
In addition, each of the elements A to E was applied with a driving voltage, and a high voltage of 1 kV was applied to the anode electrode to drive the element for a long time. The time-dependent change of the emission current during driving was the largest in the element E where the preliminary driving was not performed, and then the time-dependent change of the element A was large. Regarding the devices B, C, and D, the emission current decreased and fluctuated little, and stable electron emission characteristics were obtained for a long time.
[0061]
[Table 1]

[0062]
(Example 2)
A plurality of electron-emitting devices were prepared in the same manner as in Example 1, and the prepared electron-emitting devices were preliminarily driven.
The preliminary driving was performed by setting the anode voltage to 0 V and applying a voltage to the device electrode 2. The applied voltage was a pulse voltage as shown in FIG. 10A, the pulse width T1 was 0.5 msec, the pulse width T12 = 0.1 msec, and the pulse interval T2 was 16.7 msec. The voltage Vf1 is changed in increments of 0.1V in the range of 14V to 16V for each element. In each case, the voltage Vf12 is 0.9Vf1,
[0063]
[Formula 6]

The preliminary driving was terminated when the rate of change in the value of S was within 5%.
[0064]
Next, If-Vf characteristics were measured for each electron-emitting device that was preliminarily driven. A voltage was applied to the device electrode 2 in increments of 0.1 V from 16 V to 12 V, and the device current If flowing at that time was measured.
From the measured If-Vf characteristics, the device current If2 when the drive voltage is 14 V is 0.8If1, 0.7If1, 0.5If1, and 0.3If1, respectively, with respect to the device current If1 at the preliminary drive voltage. Preliminary driving voltages were obtained, and preliminary driving voltages of the elements F, G, H, and I were determined as shown in Table 2, and preliminary driving was performed in the same manner as the above preliminary driving. For comparison, the element J was not driven preliminarily but was driven at 14V.
[0065]
With respect to the elements F to J, a driving voltage of 14 V was applied and a high voltage of 1 kV was applied to the anode electrode, and the emission current was measured. As a result, a good emission current was obtained for all the elements.
Further, for each of the elements F to J, a driving voltage of 14 V was applied, and a high voltage of 1 kV was applied to the anode electrode to drive the elements for a long time. The time-dependent change of the emission current during driving was greatest in the element J where the preliminary driving was not performed, and then the time-dependent change of the element F was large. With respect to the elements G, H, and I, emission current decreased and fluctuated little, and stable electron emission characteristics were obtained for a long time.
[0066]
[Table 2]

[0067]
(Example 3)
A plurality of electron-emitting devices (devices K, L, M, and N) were prepared in the same manner as in Example 1, and the prepared electron-emitting devices were preliminarily driven at 15 V as in Example 1.
The preliminary driving was performed by setting the anode voltage to 0 V and applying a voltage to the device electrode 2. The applied voltage is a pulse voltage as shown in FIG. 10B, Vf1 = 15 V, pulse width T1 is 0.2 msec, Vf12 = 14.8 V, pulse width T12 = 0.1 msec.
The pulse interval T2 is 16.7 msec.
[0068]
[Expression 7]

We went while looking at the rate of change of the value.
[0069]
Preliminary driving is performed until the rate of change of the value of S reaches about 10% for the element K, until the rate of change of the value of S reaches about 7% for the element L, and the above S for the element M. This was performed until the rate of change of the value of about 5%, and for the element N, the rate of change of the value of S was about 3%.
[0070]
Next, for each electron-emitting device that was preliminarily driven, a driving voltage of 14.2 V was applied, and a high voltage of 1 kV was applied to the anode electrode to drive the device for a long time. The time-dependent change in the emission current during driving was the largest in the element K, and then the time-dependent change in the element L was large. With respect to the elements M and N, the emission current decreased and fluctuated little, and stable electron emission characteristics were obtained over a long period of time.
[0071]
【The invention's effect】
As described above, according to the driving method of the present invention, it is possible to suppress thermal deterioration of the electron emission portion during driving and obtain a stable emission current for a long time. Further, according to the manufacturing method of the present invention, an electron-emitting device is obtained in which the emission current is stable for a long time, that is, it can be used for an image forming apparatus and can maintain brightness and contrast suitable for image display for a long time. be able to.
[Brief description of the drawings]
FIG. 1 is a graph showing an example of the relationship between an emission current Ie, a device current If, and a device voltage Vf for an electron-emitting device according to the present invention.
FIG. 2 is a graph showing an example of the relationship between the emission current Ie, the device current If, and the device voltage Vf for the electron-emitting device according to the present invention.
FIG. 3 is a schematic view of a planar electron-emitting device according to the present invention.
FIG. 4 is a schematic view of a vertical electron-emitting device according to the present invention.
FIG. 5 is a schematic view showing a method for manufacturing the electron-emitting device of the present invention.
FIG. 6 is a schematic diagram showing a vacuum apparatus provided with a measurement system applicable to the present invention.
FIG. 7 is a schematic diagram showing an example of a voltage waveform that can be employed in the method of manufacturing an electron source according to the present invention.
FIG. 8 is a schematic diagram showing an example of a voltage waveform that can be employed in the method of manufacturing an electron source according to the present invention.
FIG. 9 is a graph showing an example of the relationship between the device current If and the device voltage Vf for the electron-emitting device according to the present invention.
FIG. 10 is a schematic diagram showing an example of a voltage waveform that can be employed in the method of manufacturing an electron source according to the present invention.
[Explanation of symbols]
1: substrate, 2: 3, element electrode, 4: conductive thin film, 5: electron emission part, 6: step forming part, 61: vacuum vessel, 62: power supply, 63: ammeter for measuring element current If, 64 Anode electrode 65: High-voltage power supply 66: Ammeter for measuring emission current Ie 67: Exhaust device 68: Activated substance container

Claims (4)

By applying a voltage V f1 between the device electrodes of an electron-emitting device comprising a pair of opposing device electrodes formed on a substrate and a conductive thin film including an electron-emitting portion formed between the device electrodes. after the step of flowing a current I f1 between the device electrodes with respect to the current I f1, by applying a voltage V f2 which current I f2 is I f2 ≦ 0.7I f1 between the device electrodes A driving method of an electron-emitting device to be driven,
Step of flowing the current I f1 between before Symbol device electrodes, | Vf11 | ≦ | Vf1 | voltage VF11 and a small absolute value voltage Vf12 voltage than the voltage VF11 is by applying between the device electrodes , from the current If11 and If12 flows corresponding to each of the voltage V f11 and the voltage V f12 between the device electrodes,

The calculated, until the rate of change of the value of the S is less than 5%, the driving method of the electronic emission elements, characterized in that the pre-Symbol voltage Vf1 is a process to be applied between the device electrodes. Said voltage V f1 Is the voltage V f11 The method of driving an electron-emitting device according to claim 1, wherein A pair of opposing device electrodes formed on the substrate and a conductive thin film including an electron emission portion formed between the device electrodes, and a voltage V f2 is applied between the device electrodes to A method of manufacturing an electron-emitting device that is driven by passing a current If2 through
Wherein after forming the electron emission portion has a voltage applying step of applying a higher voltage Vf1 than the voltage V f2 between the device electrodes,
The voltage application step, | Vf11 | ≦ | Vf1 | by the a is a voltage VF11 and voltage Vf12 absolute value of the voltage is smaller than the voltage VF11 applied between the device electrodes, the voltage V f11 and the V f12 each of the current If11 and If12 flowing between the device electrodes in response to the,

Look, a step of applying to the rate of change of the value of the S is less than 5%, the pre-Symbol voltage Vf1 between the device electrodes,
Wherein such relationship between the current I f2 and current I f1 to the voltage application step is completed just before flowing between the device electrodes is I f2 ≦ 0.7I f1, setting the voltage V f1 in the voltage application step the method of manufacturing electron-emitting device characterized. Said voltage V f1 Is the voltage V f11 The method of manufacturing an electron-emitting device according to claim 3, wherein

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