JP3904438B2 - Droplet ejection head, ink cartridge, ink jet recording apparatus, microactuator, micropump, optical device, image forming apparatus, apparatus for ejecting droplets - Google Patents

Description

【００４８】
なお、（１）式において、Ｆ：電極間に働く力、ε：誘電率、Ｓ：電極の対向する面の面積、ｄ：電極間距離、 Ｖ：印加電圧である。
【００４９】
このように、このインクジェットヘッドにおいては、絶縁性薄膜で形成した振動板１０の一方の面にそれぞれ電気的に分離独立した電極１４を設け、電極１４の対向する電極１４ａと電極１４ｂ間に電位差を生じる電圧を印加することによって、隣り合う電極１４ａと電極１４ｂとの間で静電引力が発生し、電極１４のわずかな変位により振動板１０の大きな変位を得ることができ、滴吐出効率が向上し、高画質記録が可能になる。
【００５０】
そして、このヘッドのマイクロアクチュエータにおいては、振動板１０に設けた構造体自体が電極１４として働くので、従前のようにシリコン構造体に電極を成膜などの方法により形成するという困難な工程の必要がなく、コストダウンを図ることが可能であり、また、構造体間の非常に狭い間隔に電極を形成することによって生じるショートなどの不良も低減できる。さらに、構造体に電極を形成した後に電極を櫛の歯状に分離するという工程も必要がなく、低コスト化、大量生産が容易である。
【００５１】
さらに、振動板１０が絶縁性薄膜からなり、振動板１０と電極１４と電気的に分離しているので、従来のように電極に電圧を印加してもシリコン振動板を介してすべての電極が同電位になって作動不良になることもなく、電極１４に印加した電圧が振動板１０側にリークすることもなく、効率良く電極１４に電圧を印加することができる。また、振動板１０が絶縁性を有し、電極１４と絶縁分離されていることで、駆動電圧が液（ここではインク）に印加されることがなく、駆動電厚印加時の電気分解による液の変質が発生することがなく、信頼性が向上し、高画質記録が可能になる。
【００５２】
次に、本発明の第２実施形態に係るインクジェットヘッドについて図６及び図７を参照して説明する。図６は同ヘッドの振動板長手方向の断面説明図、図７は同ヘッドの振動板短手方向の断面説明図である。
この実施形態では、振動板１０を形成する絶縁性薄膜として、引っ張り応力を有し、絶縁性を有する有機樹脂膜であるポリイミド膜１０Ｂを用いている。このポリイミド膜１０Ｂの膜厚は３μｍとした。
【００５３】
このように、引っ張り応力のポリイミド膜１０Ｂで振動板１０を形成することによって挫屈による振動板１０の変形が発生せず、振動板１０を形成することができた。また、ヤング率が小さいので厚さ３μｍで形成することができたため、振動板１０のピンホールの発生がなくなる。さらに、振動板１０を形成するポリイミド（有機樹脂材料）は、液に対する耐腐食性に優れるので、アルカリ性や酸性の種々の化学的性質を有する液に対しても溶出することがなく、十分な信頼性をもって液滴を吐出することができる。
【００５４】
次に、本発明の第３実施形態に係るインクジェットヘッドについて図８及び図９を参照して説明する。図８は同ヘッドの振動板長手方向の断面説明図、図９は同ヘッドの振動板短手方向の断面説明図である。
この実施形態では、絶縁性を有する振動板１０を絶縁性薄膜の積層膜で構成したものである。すなわち、振動板１０は、引っ張り応力を有する絶縁性を有する膜である窒化シリコン膜１０Ａと圧縮応力を有する膜である酸化シリコン膜１０Ｃとの積層膜で形成している。
【００５５】
ここでは、窒化シリコン膜１０Ａの膜厚は１５０ｎｍ、酸化シリコン膜１０Ｃの膜厚は１５０ｎｍとした。また、窒化シリコン膜１０Ａの引っ張り応力の維持したまま応力を緩和するために、第１実施形態の結果からイオン注入法により不純物原子であるリン原子を導入した。
【００５６】
このように、振動板１０を絶縁膜の積層膜である絶縁性薄膜で形成し、特に引っ張り応力の膜（ここでは窒化シリコン膜）と圧縮応力の膜（ここでは酸化シリコン膜）との積層膜とすることで、各膜の異なる内部応力を独立に制御することによって、振動板１０の挫屈による撓み変形を防止することができる。
【００５７】
また、シリコンの異方性エッチングを用いて吐出室６を形成する場合、窒化シリコン膜１０Ａがエッチングストッパーとして機能するので振動板１０にダメージを与えることがなくなる。さらに、酸化シリコン膜１０Ｃを厚さを１５０ｎｍ、窒化シリコン膜１０Ａの厚さを１５０ｎｍに設定することで３００dpiや６００dpiに微細化した場合でも十分な剛性が得られ、液滴吐出速度、吐出量ともに十分マージンをもって吐出することが確認できた。さらにまた、窒化シリコン膜１０Ａと酸化シリコン膜１０Ｂの積層振動板であることからピンホールの発生を防止することができる。
【００５８】
次に、本発明の第４実施形態に係るインクジェットヘッドについて図１０及び図１１を参照して説明する。図１０は同ヘッドの振動板長手方向の断面説明図、図１１は同ヘッドの振動板短手方向の断面説明図である。
この実施形態では、振動板２０を主たる層であって導電性膜でもあるシリコン膜と絶縁膜との積層膜としたものである。すなわち、振動板２０は、主たる層であるシリコン膜２０Ａとこのシリコン膜２０Ａの吐出室６と反対の面（電極側面）に形成した絶縁性薄膜であるシリコン酸化膜２０Ｂとで形成し、シリコン酸化膜２０Ｂの表面に複数の電極１４を設けている。
【００５９】
シリコン膜２０Ａは、ここでは、第１基板１を形成するシリコン基板にボロン原子を０．５μｍの深さまで１Ｅ２０/ｃｍ³個含有させた高濃度ボロン拡散層である。ボロン原子の導入法として塗布拡散法や気相拡散法等の熱拡散法やイオン注入法を検討したが、中でもイオン注入法がシリコン膜厚を決定する拡散深さの制御が一番良好であることが確認された。そこで、ここでは、イオン注入法を用いてボロン原子をイオン注入法によって導入した。シリコン膜２０Ａの膜厚はボロン原子をイオン注入法によって導入した拡散深さによって制御したため設計値通りのシリコン厚に高精度で形成することができた。
【００６０】
ここで、振動板の主たる層をシリコンで形成する場合、その厚みを５μｍ以下にすることによって、振動板の剛性を確保しながら、かつ、低電圧駆動を行うことができるようになる。
【００６１】
また、このように振動板２０の主たる層が導電性を有するシリコン膜２０Ａであっても、絶縁性薄膜であるシリコン酸化膜２０Ｂを形成して、このシリコン酸化膜２０Ｂの表面に複数の電極１４を設けるため、シリコン膜２０Ａと電極１４とは電気的に絶縁分離され、電極１４に駆動電圧を印加した場合に、従前のようにシリコン振動板の凸部に電極膜を形成するために各電極間が略同電位になるという不都合もなく、電極１４に印加した電圧がシリコン膜２０Ａにリークすることなしに電圧を印加でき、効率的な駆動を行うことができる。
【００６２】
次に、本発明の第５実施形態に係るインクジェットヘッドについて説明する。なお、この実施形態は第４実施形態のシリコン膜２０Ａに注入する原子を変更したものであるので前述した図１０及び図１１を兼用して説明する。
すなわち、この実施形態においては、振動板２０の主たる層であるシリコン膜２０Ａは、シリコン基板にイオン注入法によってリン原子を０．５μｍの深さまで１Ｅ２０/ｃｍ³個含有させ電気化学エッチング法を用いて吐出室６を形成すると同時に形成したものである。シリコン膜２０Ａの膜厚はイオン注入法によって導入したリン原子の拡散深さによって制御しているため設計値通りの高精度のシリコン厚を形成することができる。
【００６３】
また、第４実施形態と同様に、振動板２０の主たる層が導電性を有するシリコン膜２０Ａであっても、絶縁性薄膜であるシリコン酸化膜２０Ｂを形成して、このシリコン酸化膜２０Ｂの表面に電極１４を設けるため、シリコン膜２０Ａと電極１４とは電気的に絶縁分離され、電極１４に駆動電圧を印加した場合に、従前のようにシリコン基板からなる振動板の凸部に電極膜を形成するために各電極間が略同電位になるという不都合もなく、電極１４に印加した電圧がシリコン膜２０Ａにリークすることなしに電圧を印加でき、効率的な駆動を行うことができる。
【００６４】
次に、これらの第４、第５実施形態の他の例に係るインクジェットヘッドについて図１２を参照して説明する。なお、同図は同ヘッドの振動板短手方向に沿う断面説明図である。
この例においては、電極１４と同一材料の層又は構造体であるスペーサ２５を振動板２０以外の領域で電極１４を形成する面と略同一平面に形成している。このスペーサ２５は電極１４と同時に形成することができ、振動板領域以外の電極材料を除去しないことで形成することができる。
【００６５】
このようなスペーサ２５を設けることにより第１基板１を第２基板２に接合する前の工程において、微小な構造体である電極１４を保護することができ、製造工程においてウェハ搬送や、プロセス中における電極１４の破損による不良を低減することができる。
【００６６】
次に、これらの第４、第５実施形態の更に他の例に係るインクジェットヘッドについて図１３を参照して説明する。なお、同図は同ヘッドの振動板短手方向に沿う断面説明図である。
この例においては、電極１４と同一材料の層又は構造体であるスペーサ２５を振動板２０以外の領域で電極１４を形成する面と略同一平面に形成するとともに、このスペーサ２５の厚さを電極１４の厚さよりも厚く形成している。この場合、第２基板２は平板板基板をそのまま用いることができ凹部を形成する必要がなくなる。
【００６７】
このような構造とすることによって第２実施形態よりもさらに電極１４はスペーサ２５のために接触して破損することが少なくなり、電極破損による不良を低減することができる。また、第１基板１の下に保護基板（第２基板２）を接合する場合、保護基板に凹部を形成しなくても良いという利点もある。
【００６８】
ここで、上記第４及び第５実施形態の他の例に係るインクジェットヘッドの製造工程について図１４乃至図１６を参照して説明する。
ここでは、電極１４を単結晶シリコンで形成している。また、振動板２０を形成する主たる膜であるシリコン膜２０Ａは、高濃度ｐ型不純物層であって、高濃度ｐ型不純物層は所望の振動板厚と同じだけの厚さ、ここでは１．０μｍを有している。
【００６９】
すなわち、図１４（ａ）に示すように第１基板１となる（１１０）を面方位とする厚さ４００μmのシリコン基板４１に、イオン注入法によりボロン又はリンを拡散し、シリコン膜２０Ａである高濃度ボロン拡散層又は高濃度リン拡散層（これらを「高濃度不純物拡散層」という。）４２を形成する。ここでは、深さ１．０μｍの高濃度不純物拡散層４２を形成した。
【００７０】
なお、高濃度不純物拡散層４２が高濃度ボロン拡散層の場合、拡散層の表面にはシリコンとボロンの化合物層が形成されるが、この層を除去するためには、化合物層を熱酸化し、フッ酸系エッチング液によりエッチングすることによって除去できる。また、ボロン又はリンがシリコン中に拡散した面は面荒れが生じ、後の直接接合で強固な接合が得られないことがある。そのために拡散面をポリッシュして平滑な面を形成しておく。さらに、第１基板１となる基板としては、（１１０）面方位のシリコン基板に代えて、（１００）面方位のシリコン基板を用いても良い。
【００７１】
次いで、同図（ｂ）に示すように化合物層を除去しポリッシュした後に９００℃／５分のウェット酸化によりシリコン酸化膜２０Ｂとなる熱酸化膜４３を５０ｎｍ厚みで形成する。ここで、酸化膜の成膜方法としては、プラズマＣＶＤ、スパッタ、ＨＴＯ、ＴＥＯＳなどがあるが、絶縁耐圧、欠陥、残留電荷、耐久性などの点で熱酸化膜が好ましい。
【００７２】
そして、同図（ｃ）に示すように、電極１４を形成するための別のシリコン基板４４を用意し、このシリコン基板４４をシリコン基板４１の高濃度不純物拡散層４２側に直接接合する。ここでは、シリコン基板４４として（１００）面方位のシリコンウェハを用いた。表面性の良いシリコンウェハを貼り合わせ高温加熱することによって２枚のウェハは強固に接合される。ここでは１０００℃／２時間の加熱処理をした。
【００７３】
その後、同図（ｄ）に示すように、シリコン基板４４を所望の電極１４の長さ（高さ）となる厚さ２０μｍまで研磨する。
【００７４】
次いで、図１５（ａ）に示すように、フォトリソにより研磨したシリコン基板４４上にレジストパターンを形成し、ドライエッチングによりシリコン基板４４を間隔０．５μｍ、幅０．５μｍの線幅でエッチングし電極１４を形成するとともに、スペーサ２５を形成する。電極１４の形状は、例えば図４のように櫛の歯形状となっている。エッチングは酸化膜４３がストップ層となる。非常に深い溝を細くエッチングする必要があるのでドライエッチングはＩＣＰが有効である。
【００７５】
そして、同図（ｂ）に示すようにＬＰ−ＣＶＤで水酸化カリウムエッチングのマスクとなるシリコン窒化膜４６を形成する。その後、同図（ｃ）に示すように、シリコン窒化膜４６上に吐出室６や共通液室８などの形状のレジストパターンを得て、レジストの開口部のシリコン窒化膜４６と酸化膜４３をドライエッチによりエッチング除去し、レジストを除去する。
【００７６】
その後、図１６（ａ）に示すように、高濃度不純物拡散層４２が高濃度ボロン拡散層の場合には、例えば８０℃の２５ｗｔ％の水酸化カリウム水溶液でシリコン窒化膜４６および酸化膜４３の開口部からシリコン基板４１を高濃度ボロン拡散層に達する直前（残り１０μｍ程度）まで、エッチングを行う。次に、エッチング液をＩＰＡを過飽和状態にした８０℃の３０ｗｔ％の水酸化カリウム水溶液に変え、エッチングを継続して、高濃度ボロン拡散層に達するとエッチングは自発的に停止する。
【００７７】
ここで、２５ｗｔ％の水酸化カリウム水溶液ではエッチレートが大きく、また安定したエッチングが得られる。また、ＩＰＡ添加３０ｗｔ％の水酸化カリウム水溶液ではシリコン基板と高濃度ボロン層のエッチング選択比が大きく、精度よくエッチングストップができる。ＩＰＡは沸点が低く熱を加えると蒸発が激しいので、蒸気を冷却して液化しエッチング槽に戻してやる環流装置を付けるのが好ましい。高濃度ボロン拡散層のエッチング選択比を大きくできるエッチング液としてはＩＰＡ添加の水酸化カリウム以外では、３wt％〜１０wt％程度の低濃度の水酸化カリウム水溶液やＥＤＰなどでも良い。
【００７８】
また、高濃度不純物拡散層４２が高濃度リン拡散層の場合には、８０℃の２５ｗｔ％の水酸化カリウム水溶液中に基準電極を設置し、ベース基板と高濃度リン拡散層との間に逆バイアスを印加しながら、シリコン窒化膜４６及び酸化膜４３の開口部をマスクとして高濃度リン拡散層に達するまで、電気化学エッチングを行う。電気化学エッチングを行うことにより高濃度リン拡散層の深さでエッチングは自発的にストップする
【００７９】
その後、同図（ｂ）に示すように、シリコン窒化膜４６は熱リン酸、フッ酸などによって、熱酸化膜４３をフッ酸などで除去（振動板部分は残る）して、吐出室６及び吐出室６の底壁をなす１μｍの厚さのシリコン膜２０Ａである高濃度不純物拡散層４２とシリコン酸化膜２０Ｂである熱酸化膜４３からなるシリコンの振動板２０を形成する。
【００８０】
ここでは、電極１４を単結晶シリコンで形成しているので、ウェハ貼り合わせ後の研磨により電極１４の厚さ（長さ）を決めることができ、成膜では不可能な厚さの厚い電極を形成することができる。電極が厚い（高さが高い）と小さな力で振動板を変形させることができ、低電圧で駆動することが可能となる。また、貼り合わせたシリコンウェハ４４の電極として用いていない領域を利用して、液滴吐出ヘッドの駆動回路を集積化することも可能である。シリコンウェハ４４は半導体素子形成に用いるものそのものなので駆動回路を形成するのに好適である。
【００８１】
また、高濃度ボロン拡散層或いは高濃度リン拡散層の形成にはイオン注入のほかに固体拡散、塗布拡散やボロン又はリンをドープしたエピタキシャル層によっても形成することもできる。イオン注入では浅い拡散層を精度良く形成することができるので、薄い振動板を形成するのに好適である。また、エピタキシャル層では、シリコン基板の上にボロン又はリンをドープした層を成長させるので、固体拡散、イオン注入、塗布拡散に比べ、高濃度ボロン領域又は高濃度リン領域の境界が明確になり、急峻なエッチングストップを実現できより精度の良い振動板を形成することができる。
【００８２】
なお、上述したように電極１４に単結晶シリコン（或いはポリシリコンの場合も同様）などの半導体を用いた場合には、高周波数駆動、多チャンネル駆動を行うと電極の電気抵抗値が問題となることがある。この場合には、ｎ型又はｐ型の伝導型を有する不純物原子、例えばｎ型であればリン、砒素、ｐ型であればボロンやアンチモン等を導入することが好ましい。
【００８３】
次に、本発明の第６実施形態に係るインクジェットヘッドについて図１７及び図１８を参照して説明する。なお、図１７は同ヘッドの振動板長手方向の断面説明図、図１８は同ヘッドの振動板短手方向の断面説明図である。
この実施形態では、振動板５０は、液室形成時のシリコンエッチングに対してエッチング選択性を有する膜である酸化シリコン膜５０Ａと、主たる層である引っ張り応力を有する窒化シリコン膜５０Ｂと、電極１４形成時に電極材であるシリコンエッチングに対してエッチング選択性を有する酸化シリコン膜５０Ｃとの積層膜で構成し、酸化シリコン膜５０Ｃの面に複数の電極１４を設けている。
【００８４】
なお、酸化シリコン膜５０Ａの厚さは５０ｎｍ、窒化シリコン膜５０Ｂの厚さは１５０ｎｍ、酸化シリコン膜５０Ｃの厚さは５０ｎｍとしている。また、窒化シリコン膜５０Ｂの引っ張り応力の維持したまま応力を緩和するために、ここでもイオン注入法により不純物原子としてリンを導入している。
【００８５】
このように、第１基板１にシリコン基板を用いて、液室形成時のシリコンエッチング時や電極材のシリコンエッチングに選択性を有する酸化シリコン膜５０Ａ、５０Ｃを設けたので、各エッチング工程時に振動板５０の主たる層となる窒化シリコン膜５０Ｂへのエッチングダメージを防止することができて、より高精度の振動板５０を形成することができる。また、酸化シリコン膜５０Ａは、液に対する耐腐食性膜として作用するため、新たに耐腐食性膜を形成する必要がなく工程を短縮できる。
【００８６】
また、振動板５０の主たる層である窒化シリコン膜５０Ｂは引張り応力を有しているので、挫屈による撓み変形が発生せず電極１４、１４間に発生する静電引力の振動板面内でのバラツキを低減することができる。さらに、窒化シリコン膜５０Ｂを基体となる振動板５０の一部に用いているため、実効的な剛性を向上させることができ、より薄い振動板で３００dpi、６００dpiの微細化した場合においても液滴の吐出を確実に効率的に行うことができる。
【００８７】
次に、本発明の第７実施形態に係るインクジェットヘッドについて図１９及び図２０を参照して説明する。なお、図１９は同ヘッドの振動板長手方向の断面説明図、図２０は同ヘッドの振動板短手方向の断面説明図である。
この実施形態では、振動板６０は、液室形成時のシリコンエッチングに対してエッチング選択性を有する膜６０Ａとしての窒化シリコン膜６０Ａａと酸化シリコン膜６０Ａｂとの積層膜と、主たる層である引っ張り応力を有する窒化シリコン膜６０Ｂと、電極１４形成時に電極材であるシリコンエッチングに対してエッチング選択性を有する酸化シリコン膜６０Ｃとの積層膜で構成している。
【００８８】
なお、膜６０Ａのうちの窒化シリコン膜６０Ａａは厚さ５０ｎｍ、同じく酸化シリコン膜６０Ａｂは厚さ５０ｎｍとし、主たる層である引っ張り応力を有する窒化シリコン膜６０Ｂは厚さ１５０ｎｍとし、エッチング選択性を有する酸化シリコン膜６０Ｃの厚さは５０ｎｍとした。また、ここで主たる層である窒化シリコン膜６０Ｂの引っ張り応力を維持したまま応力を緩和するためにイオン注入法により不純物原子として砒素を導入している。
【００８９】
このように液室形成時のシリコンエッチング時にシリコンエッチングに選択性を有する窒化シリコン膜６０Ａａと酸化シリコン膜６０Ａｂの積層膜と、電極材のシリコンエッチングに選択性を有する酸化シリコン膜６０Ｃを設けたので、各エッチング時に振動板６０の主たる層である窒化シリコン膜６０Ｂへのエッチングダメージに対するマージンは第６実施形態の場合より向上する。その結果、振動板の主たる層である窒化シリコン膜６０Ｂへのダメージはまったく発生せず、高精度の振動板を形成することができる。
【００９０】
また、振動板６０の主たる層である窒化シリコン膜６０Ｂは引張り応力を有しているので、挫屈による撓み変形が発生せず電極１４、１４間に発生する静電引力の振動板面内でのバラツキを低減することができる。さらに、窒化シリコン膜６０Ｂを基体となる振動板５０の一部に用いているため、実効的な剛性を向上させることができ、シリコンの場合よりも薄い振動板で３００dpi、６００dpiの微細化した場合においても液滴の吐出を確実に効率的に行うことができる。
【００９１】
次に、本発明の第８実施形態に係るインクジェットヘッドについて図２１及び図２２を参照して説明する。なお、図２１は同ヘッドの振動板長手方向の断面説明図、図２２は同ヘッドの振動板短手方向の断面説明図である。
この実施形態では、振動板７０は、液室形成時のシリコンエッチングに対してエッチング選択性を有する酸化シリコン膜７０Ａと、主たる層である単結晶シリコン薄膜７Ｂと、電極１４形成時に電極材であるシリコンエッチングに対してエッチング選択性を有する酸化シリコン膜７Ｃとの積層膜で構成している。
【００９２】
なお、窒化シリコン膜７０は厚さ５０ｎｍ、主たる層である単結晶シリコン薄膜７０Ｂは厚さ０．５μｍ、エッチング選択性を有する酸化シリコン膜７０Ｃの厚さは５０ｎｍとした。
【００９３】
このように、液室形成時のシリコンエッチング時や電極材のシリコンエッチングに選択性を有する酸化シリコン膜７０Ａ、７０Ｃを設けたので各エッチング工程時に主たる層である単結晶シリコン薄膜７０Ｂへのエッチングダメージは観察されず高精度の振動板が形成できる。また、酸化シリコン膜７０Ａは液に対する耐腐食性膜として作用するため新たに耐腐食性膜を形成する必要がなく工程が短縮できる。さらに、振動板７０の主たる層である単結晶シリコン膜７０Ｂは結晶粒界や結晶欠陥がないので振動板の長期信頼性を十分確保することができる。
【００９４】
次に、本発明の第９実施形態に係るインクジェットヘッドについてその製造工程とともに図２３乃至図２５を参照して説明する。
この実施形態では主たる層をなすシリコン膜を多結晶シリコン膜で、電極１４をポリシリコン（多結晶シリコン）で形成したものである。主たる層をなすシリコン膜を多結晶シリコン膜で形成することにより、ＣＶＤ法により形成することができて膜厚制御性が向上する。
【００９５】
すなわち、図２３（ａ）に示すように、（１１０）を面方位とする厚さ４００μｍのシリコン基板８１をベース基板とし、このシリコン基板８１に酸化シリコン膜８２を厚さ５０ｎｍで形成し、この酸化シリコン膜８２の表面に膜厚１．０μｍの多結晶シリコン膜８３を形成した第１基板１となる基板８０を用意する。
【００９６】
ここで、多結晶シリコン膜８３には、内部応力を緩和するために伝導型がｎ型、又はｐ型を示す原子であるボロンやリン原子を導入するのが好ましく、この実施形態ではボロン原子を導入した。一方、酸化シリコン膜８２は、熱酸化法、ＣＶＤ法、スパッタ法などによって形成する。この酸化シリコン膜８２は、後工程のシリコン液室形成時のエッチング選択性を有する膜である。
【００９７】
次いで、同図（ｂ）に示すように、基板８０の全面にＣＶＤ法により酸化シリコン膜８４を形成する。ここで、酸化シリコン膜８４の成膜方法としては、プラズマＣＶＤ、スパッタ、ＨＴＯなどがあるが、絶縁耐圧、耐久性などの点でＨＴＯが好ましい。
【００９８】
そして、同図（ｃ）に示すように、酸化シリコン膜８４の表面に電極１４を形成するためのポリシリコン８５を５μｍの厚みに成膜し、上面のポリシリコン層をエッチング除去する。
【００９９】
その後、同図（ｄ）に示すように、フォトリソによりポリシリコン８５上にレジストパターンを形成し、ドライエッチングによりポリシリコンを間隔１μｍ、０．５μｍの線幅でエッチングして、電極１４及び前述したスペーサ２５を形成する。このとき、酸化シリコン膜８４がエッチングストップ層をなすため、振動板の主たる層となる多結晶シリコン８３に対するダメージが防止できた。なお、電極１４の形状は図４に示したような櫛歯形状とした。
【０１００】
次いで、図２４（ａ）に示すように、全面にＬＰ−ＣＶＤで水酸化カリウムエッチングのマスクとなるシリコン窒化膜８６を形成し、同図（ｂ）に示すようにシリコン窒化膜８６上に吐出室６や共通液室８などの液室形状のレジストパターンを形成し、次に、レジストの開口部のシリコン窒化膜８６と酸化シリコン膜８３をドライエッチによりエッチング除去し、レジストを除去して、マスクパターンを形成する。
【０１０１】
その後、同図（ｃ）に示すように、８０℃の２５ｗｔ％の水酸化カリウム水溶液でシリコン窒化膜８６及び酸化シリコン膜８３の開口部をエッチングする。エッチングが酸化シリコン膜８２に達すると、酸化シリコン膜８２はほとんどエッチングされないので、振動板の主たる層となる多結晶シリコン８３へのエッチングダメージは発生しなかった。
【０１０２】
ここでは、ベース基板８１には（１１０）面のシリコンウェハを用いているので、水酸化カリウムによる異方性エッチングによって（１１１）面の垂直壁が形成される。（１１０）面のウェハを用いることによって垂直壁が得られるので吐出室６を高密度に並べることができる。また、ここでは、エッチング液として、水酸化カリウム水溶液を用いたが、ＴＭＡＨ（テトラメチルアンモニウムヒドロキシド溶液）、ＥＤＰ（エチレンジアミンピロカテコール）、水酸化リチウムなどのアルカリ液でも良い。
【０１０３】
その後、同図（ｄ）に示すように、シリコン窒化膜８６を熱リン酸によって除去する。
【０１０４】
このようにして、厚さ５０ｎｍの酸化シリコン膜８２、５００ｎｍの厚さの多結晶シリコン膜８３、５０ｎｍの酸化シリコン膜８３の積層膜からなる振動板９０及び吐出室６が完成する。
【０１０５】
次に、本発明の第１０実施形態に係るインクジェットヘッドについて図２５を参照して説明する。なお、同図は同ヘッドの振動板短手方向に沿う要部断面説明図である。
この実施形態では、振動板１００は、液室形成時のシリコンエッチングに対してエッチング選択性を有する膜１００Ａとしての窒化シリコン膜１００Ａａと酸化シリコン膜１００Ａｂとの積層膜と、主たる層であるＣＶＤ法によって形成した後にボロン原子を導入した多結晶シリコン膜１００Ｂと、電極形成時に電極材であるシリコンエッチングに対してエッチング選択性を有する酸化シリコン膜１００Ｃとからなる積層膜である。
【０１０６】
なお、液室形成時のシリコンエッチングに対してエッチング選択性を有する膜１００Ａとしての窒化シリコン膜１００Ａａの膜厚は５０ｎｍ、同じく酸化シリコン膜１００Ａｂの膜厚は５０ｎｍとし、主たる層であるボロン原子を導入した多結晶シリコン膜１００Ｂの膜厚は１．０μｍとし、酸化シリコン膜１００Ｃの膜厚は５０ｎｍとした。
【０１０７】
このように、液室形成時のシリコンエッチング時にシリコンエッチングに選択性を有する窒化シリコン膜１００Ａａと酸化シリコン膜１００Ａｂの積層膜と、電極材のシリコンエッチングに選択性を有する酸化シリコン膜１００Ｃを設けたので、各エッチング工程時に多結晶シリコン膜１００Ｂへのエッチングダメージは全く発生せず高精度の振動板を形成できる。
【０１０８】
また、ＣＶＤ法によって多結晶シリコン膜１００Ｂを形成したので、膜厚の制御性が良く高精度の振動板を形成できる。さらに、多結晶シリコン膜１００Ｂにボロンを含有させることにより多結晶シリコン１００Ｂの内部応力を制御することができるため、撓みのない平坦な振動板が実現でき、電極対（１４、１４）に発生する静電引力の振動板面内バラツキを低減できる。
【０１０９】
次に、本発明の第１１実施形態に係るインクジェットヘッドについて図２６を参照して説明する。なお、同図は同ヘッドの振動板短手方向に沿う要部断面説明図である。
この実施形態では、振動板１１０は、液室形成時のシリコンエッチングに対してエッチング選択性を有する膜１１０Ａとしての窒化シリコン膜１１０Ａａと酸化シリコン膜１１０Ａｂとの積層膜と、主たる層であるＣＶＤ法によって形成した後にボロン原子を導入した窒化シリコン膜１１０Ｂと、電極形成時に電極材であるシリコンエッチングに対してエッチング選択性を有する酸化シリコン膜１１０Ｃとからなる積層膜である。
【０１１０】
なお、液室形成時のシリコンエッチングに対してエッチング選択性を有する膜１１０Ａとしての窒化シリコン膜１１０Ａａの膜厚は５０ｎｍ、同じく酸化シリコン膜１１０Ａｂの膜厚は５０ｎｍとし、主たる層であるボロン原子を導入した窒化シリコン膜１１０Ｂの膜厚は１５０ｎｍとし、酸化シリコン膜１１０Ｃの膜厚は５０ｎｍとした。
【０１１１】
このように、液室形成時のシリコンエッチング時にシリコンエッチングに選択性を有する窒化シリコン膜１１０Ａａと酸化シリコン膜１１０Ａｂの積層膜と、電極材のシリコンエッチングに選択性を有する酸化シリコン膜１１０Ｃを設けたので、各エッチング工程時に窒化シリコン膜１１０Ｂへのエッチングダメージは全く発生せず高精度の振動板を形成できる。
【０１１２】
また、ＣＶＤ法によって窒化シリコン膜１１０Ｂを形成したので、膜厚の制御性が良く高精度の振動板を形成できる。さらに、窒化シリコン膜１１０Ｂにボロンを含有させることにより窒化シリコン１１０Ｂの内部応力を引張り応力に制御することができるため、撓みのない平坦な振動板が実現でき、電極対（１４、１４）に発生する静電引力の振動板面内バラツキを低減できる。
【０１１３】
次に、第１２実施形態に係るインクジェットヘッドについてその製造工程とともの図２７及び図２８を参照して説明する。
先ず、図２７（ａ）に示すように、（１１０）を面方位とする厚さ４００μｍのシリコン基板１２１をベース基板とし、液室形成時のシリコンエッチングに対して選択性を有する厚さ５０ｎｍの窒化シリコン膜１２２ａと厚さ５０ｎｍの酸化シリコン膜１２２ｂの積層膜１２２を成膜し、この積層膜１２２に膜厚１５０ｎｍで窒化シリコン膜１２３を形成した基板１２０を用意する。
【０１１４】
ここで、窒化シリコン膜１２３は引っ張り応力を維持したまま内部応力を緩和するするためにボロンやリン原子を導入するのが好ましいので、ボロン原子をイオン注入法によって導入した。また、窒化シリコン膜１２２ａと酸化シリコン膜１２２ｂの積層膜１２２は後工程のシリコン液室形成時のエッチング選択性を有する膜である。さらに、窒化シリコン膜１２３、１２２ａと酸化シリコン膜１２２ｂはＣＶＤ法によって形成する。
【０１１５】
次いで、同図（ｂ）に示すように、全面にＣＶＤ法により酸化シリコン膜１２４を膜厚５０ｎｍに形成する。ここで、酸化シリコン膜１２４の成膜方法としては、プラズマＣＶＤ、スパッタ、ＨＴＯなどがあるが、絶縁耐圧、耐久性などの点でＨＴＯが好ましい。
【０１１６】
その後、同図（ｃ）に示すように、窒化シリコン膜１２４の表面にポリシリコン層１２５を５μｍの膜厚で成膜し、上面のポリシリコン層１２５をエッチング除去する。
【０１１７】
そして、同図（ｄ）に示すように、フォトリソによりポリシリコン層１２５上にレジストパターンを形成し、ドライエッチングによりポリシリコン層１２５を間隔１μｍ、０．５5μｍの線幅でエッチングし電極１４及びスペーサ２５を形成する。このとき酸化シリコン膜１２４がエッチングストップ層をなすため窒化シリコン膜１２３に対するダメージを防止できる。電極１４の形状は図４に示すように櫛の形状とした。
【０１１８】
次いで、図２８（ａ）に示すように、全面にＬＰ−ＣＶＤで水酸化カリウムエッチングのマスクとなるシリコン窒化膜１２６を形成する。そして、同図（ｂ）に示すように、シリコン窒化膜１２６上に吐出室６や共通液室８などの形状のレジストパターンを形成し、レジストの開口部のシリコン窒化膜１２６と酸化シリコン膜１２４をドライエッチによりエッチング除去し、レジストを除去して、マスクパターンを形成する。
【０１１９】
その後、同図（ｃ）に示すように、８０℃の２５ｗｔ％の水酸化カリウム水溶液でシリコン窒化膜１２６及び酸化シリコン膜１２４の開口部をエッチングする。このとき、窒化シリコン膜１２２ａ上でエッチングはストップし、更に酸化シリコン膜１２２ｂが積層されていることからエッチング選択性が向上しマージンが向上した。この結果、更に下に形成されている窒化シリコン膜１２３に対しては全くダメージを与えることがなくなる。
【０１２０】
ここでは、ベース基板１２１には（１１０）面のシリコンウェハを用いているので、水酸化カリウムによる異方性エッチングによって（１１１）面の垂直壁が形成される。（１１０）面のウェハを用いることによって垂直壁が得られるので吐出室を高密度に並べることができる。ここでは水酸化カリウム水溶液を用いたが、ＴＭＡＨ（テトラメチルアンモニウムヒドロキシド溶液）、ＥＤＰ（エチレンジアミンピロカテコール）、水酸化リチウムなどのアルカリ液を用いることもできる。
【０１２１】
その後、同図（ｄ）に示すように、シリコン窒化膜１２６を熱リン酸によって除去する。このようにして、厚さ５０ｎｍの窒化シリコン膜１２２ａと５０ｎｍの酸化シリコン膜１２２ｂ、１５０ｎｍの厚さの引っ張り応力を有する窒化シリコン膜１２３、５０ｎｍの酸化シリコン膜１２４の積層振動板１３０および吐出室６が完成する。
【０１２２】
次に、第１３実施形態に係るインクジェットヘッドについて図２９を参照して説明する。なお、同図は同ヘッドの振動板短手方向に沿う断面説明図である。
この実施形態では、第３実施形態のインクジェットヘッドにおける電極１４の表面に絶縁膜２６を形成している。すなわち、前述したように、駆動電圧を低くするためには、電極１４の間隔を小さくしなければならないが、そのような微小な間隔で電極１４を形成した場合、小さなダストであってもが電極１４上に載るとショートの原因となり、動作不良を起こすことがあり、また、非常に微小な間隔なので、空気の湿度によって電極１４表面に微小な水滴が発生した場合にも、ショートの原因となる。
【０１２３】
そこで、電極１４の表面に絶縁膜２６を設けることによって、電極１４間のショートによる動作不良を低減することができる。また、電圧を印加した時の電極間１４の放電により動作不良を起こすことがあるが、これに対して絶縁膜２６を設けることによって、耐圧も向上することができ、信頼性の高い液滴吐出ヘッドが得られる。
【０１２４】
ここで、絶縁膜２６としては熱酸化膜を用いることができる。すなわち、電極１４に単結晶シリコンやポリシリコンを用いた場合、熱酸化膜は電極表面に均一に精度良く形成することができる。また、熱酸化膜は機械的、電気的な信頼性が高く、信頼性の高い液滴吐出ヘッドが実現できる。
【０１２５】
この場合、熱酸化膜は約４４％のシリコンを消費しながら成長する。図３０を参照して説明すると、酸化前の電極１４は点線Ａで示す状態にあり、ギャップＧ１の間隔を隔てて設けられている。これに厚さｔの熱酸化膜（絶縁膜２６）を性膜すると、約０．４４ｔの厚さのシリコンが消費され、電極１４の間隔はＧ３、空間間隔はＧ２となる。
【０１２６】
熱酸化膜を形成する前の電気的な電極間間隔である実効ギャップＧは、Ｇ＝Ｇ１であり、厚さｔの熱酸化膜形成した場合の実効ギャップＧ’は、熱酸化膜の誘電率をεとすると、次の（２）式で表される。
【０１２７】
【数２】

【０１２８】
ここで、熱酸化膜の誘電率εは３．７〜３．９であるので、Ｇ’＜Ｇ、となり、熱酸化膜を形成することによって、実効ギャップを小さくすることができる。前述したように、電極１４、１４間に働く力は実効ギャップが小さいほど大きくでき、電極１４、１４間に働く静電力は実効ギャップの２乗に反比例する。したがって、熱酸化膜を形成して実行ギャップを小さくすることによって力を大きくする、あるいは駆動電圧を低くすることができる。電極を加工して狭い間隔を形成するのには限界があり、ドライエッチングで溝を形成した場合には０．５μｍ程度が限界である。電極表面に絶縁膜を形成することによって、この限界値よりもさらに小さい実効ギャップを形成し、駆動電圧を下げることができる。
【０１２９】
具体的に、ここで用いた熱酸化膜の誘電率は３．８であった。Ｇ１を０．５μｍ、絶縁膜厚さｔを０．４μｍとすると、実行ギャップＧ’は０．２６μｍとなり、実効ギャップを約１／２に小さくできる。前述した（１）式より、電極間に働く静電力に換算すると３．７倍となり、同じ静電力を得ようとした場合、電圧は約１／２に低電圧化することができる。
【０１３０】
すなわち、Ｇ１＝０．５5μｍ（ε＝３．８）のとき
ｔ＝０．２μｍの場合：Ｇ２＝０．２８μｍ、Ｇ’＝０．３８μｍ
ｔ＝０．４μｍの場合：Ｇ２＝０．０６μｍ、Ｇ’＝０．２６μｍ
となる。
【０１３１】
なお、シリコンを消費して成長する膜としては、熱酸化膜以外に熱窒化膜もあり、この熱窒化膜も機械的、電気的に信頼性が高く絶縁膜として用いることができる。
【０１３２】
また、絶縁膜２６としては堆積絶縁膜を用いることもできる。堆積絶縁膜は、シリコンを消費せずに膜を堆積させるものである。例えば、高温熱ＣＶＤ、低温熱ＣＶＤによるシリコン酸化膜、ＰＥ−ＣＶＤによるシリコン酸化膜やシリコン窒化膜、ＬＰ−ＣＶＤによるシリコン窒化膜、スパッタによるシリコン酸化膜、酸化チタン、酸化モリブデン、酸化タングステンなどの金属酸化膜、あるいは真空蒸着による金属膜を酸化した膜などがあげられる。構造体表面にも均一に成膜できるという点でＣＶＤによる成膜が好ましい。
【０１３３】
堆積絶縁膜の例として高温ＣＶＤによるシリコン酸化膜を成膜している。高温ＣＶＤによるシリコン酸化膜は被成膜表面に堆積して成膜されるので、成膜する前の電極面と成膜後の電極面は変化しない。したがって、厚さｔだけ成膜した場合、成膜前後の電極間隔Ｇ１は変化せず、空間間隔は膜厚分だけ狭くなったＧ２となる。
【０１３４】
ここで、堆積絶縁膜（絶縁膜２６）を形成する前の電気的な電極間間隔である実効ギャップＧは、Ｇ＝Ｇ１である。厚さｔの堆積絶縁膜を形成した場合の実効ギャップＧ’は、酸化膜の誘電率をε1とすると、次の（３）式で表される。
【０１３５】
【数３】

【０１３６】
高温ＣＶＤによるシリコン酸化膜の誘電率ε1は４．０〜４．５であるので、Ｇ’＜Ｇ、となり、酸化膜（堆積絶縁膜）を形成することによって、実効ギャップを小さくすることができる。しかも、熱酸化膜のように電極の材料を消費せずに成膜することができるので、さらに実効ギャップを小さくすることが可能であり、さらなる低電圧化が可能となる。ここで用いた酸化膜の誘電率は４．０であった。Ｇ１を０．５μｍ、ｔを０．２μｍとすると、Ｇ’は０．２μｍとなり実効ギャップを２／５に小さくできる。前述した（１）式より電極間に働く静電力に換算すると６倍となり、同じ静電力を得ようとした場合、電圧は２／５に低電圧化できる。
【０１３７】
すなわち、Ｇ１＝０．５μｍ（ε=４．０）のとき
ｔ＝０．２μｍの場合：Ｇ２＝０．１μｍ、Ｇ’＝０．２μｍ
となる。
【０１３８】
誘電率が高いほど実効ギャップを小さくする効果は大きく、その他、ＰＥ−ＣＶＤのシリコン酸化膜などさらに大きな誘電率の膜を使うことによって実効ギャップを小さくする効果が大きくなる。
【０１３９】
さらに、電極１４の表面に導電性の膜を形成することもできる。導電性の膜を電極表面に成膜することによって、成膜前に電極間隔がＧ１であったのに対し、厚さｔの成膜後電極間隔は成膜厚さの２倍だけ小さいＧ２となる。これにより、電極間隔を導電性膜の成膜により小さくすることができ、静電力の向上、駆動電圧の低電圧化が可能となる。また、電極表面に絶縁膜を形成する方法と併用して、信頼性の向上、更なる低電圧化も実現することができる。
【０１４０】
成膜する導電性膜としてはポリシリコン、あるいはスパッタや真空蒸着によるアルミニウム、ニッケル、タングステン金などの金属膜を用いることができるが、構造体である電極表面に均一に成膜できるポリシリコンがもっとも好ましい。この場合、ポリシリコン中にはｎ型又はｐ型の伝導型を有する不純物原子、例えばｎ型であればリン、砒素、ｐ型であればボロンやアンチモン等を導入することが好ましい。
【０１４１】
次に、第１４実施形態に係るインクジェットヘッドについて図３１を参照して説明する。なお、同図は同ヘッドの振動板短手方向に沿う断面説明図である。
この実施形態においては、第２基板２の凹部１６の壁面部分に電極（これを、固定電極という。）１５４を設けるとともに、振動板１０の短手方向端部側に固定電極１５４から複数の電極（これを、可動電極という。）１５５をそれぞれ所定の間隔を置いて設けている。なお、その他の構成は第３実施形態と同様である。
【０１４２】
このように構成したインクジェットヘッドの動作を説明する。固定電極１５４及び１つおきの可動電極１５５に駆動回路により０Ｖから４０Ｖのパルス電位を印加すると、固定電極１５４及び１つおきの可動電極１５５の表面がプラスに帯電し、パルス電位を印加していない隣り合う可動電極１５５との間で、図３２に示すように、静電気の吸引作用が働き、振動板１０が下方へたわむ。その結果、吐出室６の内容積が増加するので、インクが共通液室８より流体抵抗部７を通じて吐出室６内に補給される。
【０１４３】
そして、電極１５４、１５５の電位が０Ｖに戻ると、電極１５４、１５５間、１５５、１５５間に電位差はなくなり、振動板１０は元の状態に復元する。振動板１０が復元することにより、吐出室６内の圧力が急激に上昇し、ノズル孔４よりインク液滴が吐出される。すなわち、この実施形態では引き打ち法でインク滴を吐出させることができる。
【０１４４】
次に、第１５実施形態に係るインクジェットヘッドについて図３３を参照して説明する。なお、同図は同ヘッドの振動板短手方向に沿う断面説明図である。
この実施形態においては、前記第３実施形態と前記第１４実施形態とを組合せ、第２基板２の凹部１６の壁面部分に固定電極１５４を設けるとともに、振動板１０に固定電極１５４から複数の可動電極１５５をそれぞれ所定の間隔を置いて設けている。
【０１４５】
このように構成したインクジェットヘッドの動作を説明すると、固定電極１５４及び振動板短手方向端部側の可動電極１５５の群（端部側可動電極群）の１つおきの可動電極１５５に駆動回路により０Ｖから４０Ｖのパルス電位を印加すると、固定電極１５４、及び端部側可動電極群の１つおきの可動電極１５５の表面がプラスに帯電し、パルス電位を印加していない隣り合う可動電極１５５との間で、前記図３２と同様に、静電気の吸引作用が働き振動板１０が下方へたわむ。その結果、吐出室６の内容積が増加するので、インクが共通液室８より流体抵抗部７を通じて吐出室６内に補給される。
【０１４６】
そこで、固定電極１５５への電圧印加を解除するとともに、中央部の可動電極１５５を含めて、すべての可動電極１５５に対して、１つおきに０Ｖから４０Ｖのパルス電位を印加すると、電圧印加した可動電極１５５の表面がプラスに帯電し、パルス電位を印加していない隣り合う電極１５５との間で、前述した図５に示すと同様に、静電気の吸引作用が働き、振動板１０が上方へたわむ。その結果、吐出室６内の圧力が急激に上昇し、ノズル孔４よりインク液滴が吐出される。すなわち、この実施形態では、引き−押し打ち法でインク滴を吐出させることができる。
【０１４７】
次に、第１６実施形態に係るインクジェットヘッドについて図３４を参照して説明する。なお、同図は同ヘッドの振動板短手方向に沿う断面説明図である。
この実施形態においては、前記第３実施形態の振動板１０を用いて、前記複数の電極１４を吐出室６側に設けたものである。この場合、電極１４がインクによって腐食等されるのを防止するため、電極１４の表面には耐液性膜（ここでは耐インク性膜）として窒化膜等の絶縁膜１５７を形成している。
【０１４８】
このように構成した場合、複数の電極１４に１つおきにパルス電位を印加することで、振動板１０が吐出室６と反対側に変形して、吐出室６内にインクが補給され、この状態から複数の電極１４に対するパルス電位の印加を停止することで振動板１０が復元してインク滴が吐出される。すなわち、この場合は、引き打ち法と同様にしてインク滴を吐出させることができる。
【０１４９】
次に、第１７実施形態に係るインクジェットヘッドについて図３５を参照して説明する。なお、同図は同ヘッドの振動板短手方向に沿う断面説明図である。
この実施形態においては、第６実施形態の振動板５０を用いて、振動板５０の短手方向中央部では吐出室６と反対側の面に前記複数の電極１５５を設け、振動板５０の短手方向両端部では吐出室６側に前記複数の電極１５５を設けるとともに、吐出室６側の最端部の電極１５５に対向して固定電極１５４を配置したものである。なお、電極１５４、１５５がインクによって腐食等されるのを防止するため、電極１５４、１５５の表面には耐液性膜（ここでは耐インク性膜）として窒化膜等の絶縁膜１５７を形成している。
【０１５０】
このように構成したので、固定電極１５４と振動板５０の両端部側の電極１５５に対して１つおきにパルス状電位を印加して静電力を発生させるとともに、振動板５０の中央部側の電極１５５に対しても１つおきにパルス状電位を印加して静電力を発生させると、振動板５０は上下の電極１５５の変位によって吐出室６側に変形する。この場合、振動板５０の両端部と中央部で異なる変形を受けることになり、振動板５０の変形形状を理想的なガウシャン形状に近くすることができ、より滴吐出特性が向上する。
【０１５１】
次に、本発明に係るインクカートリッジについて図３６を参照して説明する。このインクカートリッジ２００は、ノズル孔２０１等を有する上記各実施形態のいずれかのインクジェットヘッド２０１と、このインクジェットヘッド２０１に対してインクを供給するインクタンク２０２とを一体化したものである。
【０１５２】
このようにインクタンク一体型のヘッドの場合、ヘッドの低コスト化、信頼性は、ただちにインクカートリッジ全体の低コスト化、信頼性につながるので、上述したように低コスト化、高信頼性化、製造不良低減することで、インクカートリッジの歩留まり、信頼性が向上し、ヘッド一体型インクカートリッジの低コスト化を図れる。
【０１５３】
本発明に係るインクジェットヘッド又はインクカートリッジを搭載した、本発明に係る液滴を吐出する装置を含む画像形成装置としてのインクジェット記録装置の一例について図３７及び図３８を参照して説明する。なお、図３７は同記録装置の斜視説明図、図３８は同記録装置の機構部の側面説明図である。
【０１５４】
このインクジェット記録装置は、記録装置本体２１１の内部に主走査方向に移動可能なキャリッジ、キャリッジに搭載した本発明に係るインクジェットヘッドからなる記録ヘッド、記録ヘッドへインクを供給するインクカートリッジ等で構成される印字機構部２１２等を収納し、装置本体２１１の下方部には前方側から多数枚の用紙２１３を積載可能な給紙カセット（或いは給紙トレイでもよい。）２１４を抜き差し自在に装着することができ、また、用紙２１３を手差しで給紙するための手差しトレイ２１５を開倒することができ、給紙カセット２１４或いは手差しトレイ２１５から給送される用紙２１３を取り込み、印字機構部２１２によって所要の画像を記録した後、後面側に装着された排紙トレイ２１６に排紙する。
【０１５５】
印字機構部２１２は、図示しない左右の側板に横架したガイド部材である主ガイドロッド２２１と従ガイドロッド２２２とでキャリッジ２２３を主走査方向（図３８で紙面垂直方向）に摺動自在に保持し、このキャリッジ２２３にはイエロー（Ｙ）、シアン（Ｃ）、マゼンタ（Ｍ）、ブラック（Ｂｋ）の各色のインク滴を吐出する本発明に係る液滴吐出ヘッドであるインクジェットヘッドからなるヘッド２２４を複数のインク吐出口を主走査方向と交叉する方向に配列し、インク滴吐出方向を下方に向けて装着している。またキャリッジ２２３にはヘッド２２４に各色のインクを供給するための各インクカートリッジ２２５を交換可能に装着している。なお、本発明に係るヘッド一体型のインクカートリッジを搭載するようにすることもできる。
【０１５６】
インクカートリッジ２２５は上方に大気と連通する大気口、下方にはインクジェットヘッドへインクを供給する供給口を、内部にはインクが充填された多孔質体を有しており、多孔質体の毛管力によりインクジェットヘッドへ供給されるインクをわずかな負圧に維持している。
【０１５７】
また、記録ヘッドとしてここでは各色のヘッド２２４を用いているが、各色のインク滴を吐出するノズルを有する１個のヘッドでもよい。
【０１５８】
ここで、キャリッジ２２３は後方側（用紙搬送方向下流側）を主ガイドロッド２２１に摺動自在に嵌装し、前方側（用紙搬送方向上流側）を従ガイドロッド２２２に摺動自在に載置している。そして、このキャリッジ２２３を主走査方向に移動走査するため、主走査モータ２２７で回転駆動される駆動プーリ２２８と従動プーリ２２９との間にタイミングベルト２３０を張装し、このタイミングベルト２３０をキャリッジ２２３に固定しており、主走査モーター２２７の正逆回転によりキャリッジ２２３が往復駆動される。
【０１５９】
一方、給紙カセット２１４にセットした用紙２１３をヘッド２２４の下方側に搬送するために、給紙カセット２１４から用紙２１３を分離給装する給紙ローラ２３１及びフリクションパッド２３２と、用紙２１３を案内するガイド部材２３３と、給紙された用紙２１３を反転させて搬送する搬送ローラ２３４と、この搬送ローラ２３４の周面に押し付けられる搬送コロ２３５及び搬送ローラ２３４からの用紙２１３の送り出し角度を規定する先端コロ２３６とを設けている。搬送ローラ２３４は副走査モータ２３７によってギヤ列を介して回転駆動される。
【０１６０】
そして、キャリッジ２２３の主走査方向の移動範囲に対応して搬送ローラ２３４から送り出された用紙２１３を記録ヘッド２２４の下方側で案内する用紙ガイド部材である印写受け部材２３９を設けている。この印写受け部材２３９の用紙搬送方向下流側には、用紙２１３を排紙方向へ送り出すために回転駆動される搬送コロ２４１、拍車２４２を設け、さらに用紙２１３を排紙トレイ２１６に送り出す排紙ローラ２４３及び拍車２４４と、排紙経路を形成するガイド部材２４５，２４６とを配設している。
【０１６１】
記録時には、キャリッジ２２３を移動させながら画像信号に応じて記録ヘッド２２４を駆動することにより、停止している用紙２１３にインクを吐出して１行分を記録し、用紙２１３を所定量搬送後次の行の記録を行う。記録終了信号または、用紙２１３の後端が記録領域に到達した信号を受けることにより、記録動作を終了させ用紙２１３を排紙する。この場合、ヘッド２２４を構成する本発明に係るインクジェットヘッドは滴吐出効率が高いので、安定して高い画像品質の画像を記録することができる。
【０１６２】
また、キャリッジ２２３の移動方向右端側の記録領域を外れた位置には、ヘッド２２４の吐出不良を回復するための回復装置２４７を配置している。回復装置２４７はキャップ手段と吸引手段とクリーニング手段を有している。キャリッジ２２３は印字待機中にはこの回復装置２４７側に移動されてキャッピング手段でヘッド２２４をキャッピングされ、吐出口部を湿潤状態に保つことによりインク乾燥による吐出不良を防止する。また、記録途中などに記録と関係しないインクを吐出することにより、全ての吐出口のインク粘度を一定にし、安定した吐出性能を維持する。
【０１６３】
吐出不良が発生した場合等には、キャッピング手段でヘッド２２４の吐出口（ノズル）を密封し、チューブを通して吸引手段で吐出口からインクとともに気泡等を吸い出し、吐出口面に付着したインクやゴミ等はクリーニング手段により除去され吐出不良が回復される。また、吸引されたインクは、本体下部に設置された廃インク溜（不図示）に排出され、廃インク溜内部のインク吸収体に吸収保持される。
【０１６４】
このように、このインクジェット記録装置においては本発明を実施したインクジェットヘッド又はインクカートリッジを搭載しているので、振動板駆動不良によるインク滴吐出不良がなく、安定したインク滴吐出特性が得られて、画像品質が向上する。また、低電圧で駆動できるヘッドを搭載するので、インクジェット記録装置全体の消費電力も低減できる。
【０１６５】
次に、本発明に係るマイクロポンプについて図３９を参照して説明する。なお、同図は同マイクロポンプの要部断面説明図である。
このマイクロポンプは、流路基板３０１と保護基板３０２とを重ねて接合した積層構造となっており、流路基板３０１には流体が流れる流路３０３を形成するとともに、流路３０３の一壁面を形成する前記液滴吐出ヘッドの実施形態で説明したような変形可能な単層又は積層の絶縁性薄膜、主たる層（シリコン膜或いは窒化シリコン膜）と絶縁性薄膜の積層膜などの可動板３０４（ここでは窒化シリコン膜３０４Ａと酸化シリコン膜３０４Ｂの積層膜で図示している。）を設け、可動板３０４の保護基板３０２と接合固定しない部分は可動部分３０５となっている。
【０１６６】
そして、可動部分３０５の流路３０３側の反対の面に、前記インクジェットヘッドと同様に、複数の電極３０７を所定の間隔を置いて設けている。保護基板３０２は前記ヘッドの第２基板２と同様な機能を有するものであり、電極３０７を配置するための凹部３０８を形成している。ここでは、保護基板３０２は平板板基板にスペーサ部３０９を設けることで凹部３０８を形成している。
【０１６７】
このマイクロポンプの動作原理を説明すると、前述したように複数の電極３０７に対して１つおきにパルス電位を与えることによって電極３０７間で静電吸引力が生じるので、可動部分３０５が流路３０３側に変形する。ここで、可動部分３０５を図中右側から順次駆動することによって流路３０３内の流体は、矢印方向へ流れが生じ、流体の輸送が可能となる。
【０１６８】
なお、この実施形態では可動部分を複数設けた例を示したが、可動部分は１つでも良い。また、輸送効率を上げるために、可動部分間に１又は複数の弁、例えば逆止弁などを設けることもできる。
【０１６９】
次に、本発明に係る光学デバイスの実施形態について図４０を参照して説明する。なお、同図は同デバイスの概略構成図である。
この光学デバイスは、変形可能なミラー４０１と保護基板４０２とを重ねて接合している。ミラー４０１は、前記液滴吐出ヘッドの実施形態で説明したような変形可能な単層又は積層の絶縁性薄膜、主たる層（シリコン膜或いは窒化シリコン膜）と絶縁性薄膜の積層膜などで構成でき、ここでは主たる層４０１Ａと絶縁性薄膜４０１Ｂの積層膜としている。
【０１７０】
このミラー４０１の保護基板４０２と接合固定しない部分は可動部分４０５となっている。そして、可動部分４０５には複数の電極４０７を所定の間隔を置いて設けている。保護基板４０２は前記ヘッドの第２基板２と同様な機能を有するものであり、電極４０７を配置するための凹部４０８を形成している。ここでは、保護基板４０２は平板板基板にスペーサ部４０９を設けることで凹部４０８を形成している。なお、ミラー３０１表面は反射率を増加させるため誘電体多層膜や金属膜を形成すると良い。
【０１７１】
この光学デバイスの原理を説明すると、ミラー４０１の可動部分４０５に設けた複数の電極４０７に対して１つおきにパルス電位を与えることによって、電極４０７間で静電吸引力が生じるので、可動部分４０５が凸状に変形して凸面ミラーとなる。したがって、光源４１０からの光がレンズ４１１を介してミラー４０１に照射した場合、ミラー４０１を駆動しないときには、光は入射角と同じ角度で反射するが、ミラー４０１を可動部分４０５を駆動した場合はその可動部分４０５が凸面ミラーとなるので反射光は発散光となる。これにより光変調デバイスが実現できる。
【０１７２】
そこで、この光学デバイスを応用した例を図４１及び図４２をも参照して説明する。この例は、上述した光学デバイスを２次元に配列し、各ミラーの可動部分４０５を独立して駆動するようにしたものである。なお、ここでは、４×４の配列を示しているが、これ以上配列することも可能である。また、電極４０７は可動部分４０５の面において格子状に分離している（前記液滴吐出ヘッドの実施形態においても、この電極４０５と同様に、電極１４を格子状に分離することもできる。）。
【０１７３】
したがって、前述した図４０と同様に、光源４１０からの光はレンズ４１１を介してミラー４０１に照射され、ミラー４０１を駆動していないところに入射した光は、投影用レンズ４１２へ入射する。一方、電極４０７に電圧を印加してミラー４０１の可動部分４０５を変形させているところは凸面ミラーとなるので光は発散し投影用レンズ４１２にほとんど入射しない。この投影用レンズ４１２に入射した光はスクリーン（図示しない）などに投影され、スクリーンに画像を表示することができる。
【０１７４】
なお、上記実施形態においては、液滴吐出ヘッドとしてインクジェットヘッドに適用した例で説明したが、インクジェットヘッド以外の液滴吐出ヘッドとして、例えば、液体レジストを液滴として吐出する液滴吐出ヘッド、ＤＮＡの試料を液滴として吐出する液滴吐出ヘッドなどの他の液滴吐出ヘッドにも適用できる。また、マイクロアクチュエータは、マイクロポンプ、光学デバイス（光変調デバイス）以外にも、マイクロスイッチ（マイクロリレー）、マルチ光学レンズのアクチュエータ（光スイッチ）、マイクロ流量計、圧力センサなどにも適用することができる。また、前述したようにプリンタ、ファクシミリ、複写装置等の画像形成装置及び液滴を吐出する装置にも本発明を適用することができる。
【０１７５】
【発明の効果】
以上説明したように、本発明に係る液滴吐出ヘッドによれば、絶縁性薄膜で形成した振動板の両面、または、片方の面に電気的に互いに絶縁分離された導電性を有する構造体からなる少なくとも２つの電極を設け、電極間に静電力を発生させて振動板を変形させる構成としたので、低コストで、滴吐出効率が高く、高画質印字が可能なヘッドが得られる。
【０１７６】
本発明に係る液滴吐出ヘッドによれば、絶縁性薄膜で形成した振動板の両面、または、片方の面に導電性を有する構造体からなる少なくとも１つの電極を設けるとともに、振動板を固定する壁面部に前記電極に所定の間隔を置いて対向する電極を設け、前記電極間に静電力を発生させることによって振動板を変形させる構成としたので、低コストで、滴吐出効率が高く、高画質印字が可能なヘッドが得られる。
【０１７７】
これらの本発明に係る液滴吐出ヘッドにおいては、振動板を形成する絶縁性薄膜は絶縁膜の積層膜とすることで各膜の応力を個別に制御できて、内部応力による振動板の挫屈撓み変形が防止でき、また、積層膜のためピンホールの発生を防止できる。
【０１７８】
また、振動板を形成する絶縁性薄膜は絶縁膜は引張り応力を有していることで、振動板の挫屈による撓み変形を回避でき、電極対に発生する静電引力の振動板面内バラツキを低減でき、更に振動板の実効的な剛性をを向上させることができてより薄い振動板で液滴を吐出できるようになる。
【０１７９】
この場合、引張り応力を有する絶縁膜として窒化シリコン膜を用いることで、液室をシリコン基板で形成するときのエッチングストッパとして機能して高精度の振動板を形成できる。この窒化シリコン膜の厚さは１０ｎｍ〜９００ｎｍの範囲内とすることで、剛性の確保と、低電圧駆動化を図れる。更に窒化シリコン膜には不純物原子が含まれていることで、容易に引っ張り応力を維持したまま応力緩和を実現できる。
【０１８０】
また、振動板を形成する絶縁性薄膜を有機樹脂膜とすることで、ヤング率が小さい材料が多いことからより厚い振動板を形成することができ、振動板のピンホール欠陥を防止できる。この有機樹脂膜としてポリイミド膜を用いることで、液の耐腐食性が向上し、化学的性質の液体も吐出することができる。
【０１８１】
本発明に係る液滴吐出ヘッドによれば、シリコンとこのシリコンの吐出室と反対側の面に設けた絶縁性薄膜の積層膜で形成した振動板の絶縁性薄膜の面に電気的に互いに絶縁分離された導電性を有する構造体からなる少なくとも２つの電極を設け、電極間に静電力を発生させることによって振動板を変形させるので、低コストで、滴吐出効率が高く、高画質印字が可能なヘッドが得られ、また振動板の厚み制御が容易になる。
【０１８２】
また、本発明に係る液滴吐出ヘッドによれば、シリコンとこのシリコンの吐出室と反対側の面に設けた絶縁性薄膜の積層膜で形成した振動板の絶縁性薄膜の面に導電性を有する構造体からなる少なくとも１つの電極を設けるとともに、固定部に前記電極に所定の間隔を置いて対向する電極を設け、電極間に静電力を発生させることによって振動板を変形させるので、低コストで、滴吐出効率が高く、高画質印字が可能なヘッドが得られ、また振動板の厚み制御が容易になる。
【０１８３】
これらの各本発明に係る液滴吐出ヘッドにおいて、振動板のシリコンには伝導型がｎ型又はｐ型の不純物原子が含まれていることで、異方性エッチングを行うときのエッチングストッパとして機能させて、高精度の振動板を形成することができる。
【０１８４】
本発明に係る液滴吐出ヘッドによれば、主たる層とシリコンエッチングに対して選択性を有する膜で形成した振動板の両面、または、片方の面に電気的に互いに絶縁分離された導電性を有する構造体からなる少なくとも２つの電極を設け、電極間に静電力を発生させることによって振動板を変形させるので、低コストで、滴吐出効率が高く、高画質印字が可能なヘッドが得られ、またエッチングで液室を形成するときの振動板の主たる層に対するエッチングダメージを防止でき、より高精度の振動板を形成できる。
【０１８５】
また、本発明に係る液滴吐出ヘッドによれば、主たる層とシリコンエッチングに対して選択性を有する膜で形成した振動板の両面、または、片方の面に導電性を有する構造体からなる少なくとも１つの電極を設けるとともに、振動板を固定する壁面部に前記電極に所定の間隔を置いて対向する電極を設け、電極間に静電力を発生させることによって振動板を変形させるので、低コストで、滴吐出効率が高く、高画質印字が可能なヘッドが得られ、またエッチングで液室を形成するときの振動板の主たる層に対するエッチングダメージを防止でき、より高精度の振動板を形成できる。
【０１８６】
さらに、本発明に係る液滴吐出ヘッドによれば、シリコンエッチングに対してエッチング選択性を有する膜／主たる層／電極材料のエッチングに対して選択性を有する膜で形成した振動板の両面、または、片方の面に電気的に互いに絶縁分離された導電性を有する構造体からなる少なくとも２つの電極を設け、電極間に静電力を発生させることによって振動板を変形させるので、低コストで、滴吐出効率が高く、高画質印字が可能なヘッドが得られ、またエッチングで液室及び電極を形成するときの振動板の主たる層に対するエッチングダメージを防止でき、より高精度の振動板を形成できる。
【０１８７】
さらにまた、本発明に係る液滴吐出ヘッドによれば、シリコンエッチングに対してエッチング選択性を有する膜／主たる層／電極材料のエッチングに対して選択性を有する膜で形成した振動板の両面、または、片方の面に導電性を有する構造体からなる少なくとも１つの電極を設けるとともに、振動板を固定する壁面部に前記電極に所定の間隔を置いて対向する電極を設け、電極間に静電力を発生させることによって振動板を変形させるので、低コストで、滴吐出効率が高く、高画質印字が可能なヘッドが得られ、またエッチングで液室及び電極を形成するときの振動板の主たる層に対するエッチングダメージを防止でき、より高精度の振動板を形成できる。
【０１８８】
これらの各本発明に係る液滴吐出ヘッドにおいては、シリコンエッチングに対してエッチング選択性を有する膜は、シリコン酸化膜、或いはシリコン窒化膜とシリコン酸化膜の積層膜であることで、振動板に対するエッチングダメージをより確実に防止できる。また、電極材料のエッチングに対してエッチング選択性を有する膜はシリコン酸化膜であることで、振動板に対するエッチングダメージをより確実に防止できる。さらに、主たる層が引張り応力を有していることで、振動板の挫屈による撓み変形を回避でき、電極対に発生する静電引力の振動板面内バラツキを低減でき、更に振動板の実効的な剛性をを向上させることができてより薄い振動板で液滴を吐出できるようになる。
【０１８９】
また、主たる層は窒化シリコン膜とすることで容易に引張り応力を維持したまま応力制御することができるようになり、或いはシリコンとすることで堆積法や研磨法を用い主たる層を形成できて厚み制御性が向上する。さらに、振動板の厚みが５μｍ以下とすることで、剛性を確保しつつ低電圧駆動化を図れる。
【０１９０】
本発明に係るインクカートリッジによれば、インク滴を吐出する本発明に係る液滴吐出ヘッドとこの液滴吐出ヘッドにインクを供給するインクタンクを一体化したので、製造不良が減少し、低コスト化を図れる。
【０１９１】
本発明に係るインクジェット記録装置によれば、インク滴を吐出するインクジェットヘッドとして本発明に係る液滴吐出ヘッド又はインクカートリッジを搭載するので、装置の低コスト化を図れる。本発明に係る画像形成装置によれば、本発明に係る液滴吐出ヘッドを備えたので、低コスト化を図ることができる。本発明に係る液滴を吐出する装置によれば、本発明に係る液滴吐出ヘッドを備えたので、低コスト化を図れる。
【０１９２】
本発明に係るマイクロアクチュエータによれば、絶縁性薄膜で形成した可動部分の両面、または、片方の面に電気的に互いに絶縁分離された導電性を有する構造体からなる少なくとも２つの電極を設け、前記電極間に静電力を発生させることによって可動部分を変形させるので、低コストで、動作効率が高いアクチュエータが得られる。
【０１９３】
本発明に係るマイクロアクチュエータによれば、絶縁性薄膜で形成した可動部分の両面、または、片方の面に導電性を有する構造体からなる少なくとも１つの電極を設けるとともに、可動部分を固定する壁面部に可動部分の電極に所定の間隔を置いて対向する電極を設け、電極間に静電力を発生させることによって可動部分を変形させるので、低コストで、動作効率が高いアクチュエータが得られる。
【０１９４】
本発明に係るマイクロポンプによれば、可動部分の変形によって液体を輸送するマイクロポンプであって、絶縁性薄膜で形成した可動部分の両面、または、片方の面に電気的に互いに絶縁分離された２つの電極を設け、電極間に静電力を発生させることによって前記可動部分を変形させるので、小型で、低消費電力化を図れるとともに、低コスト化を図れる。
【０１９５】
本発明に係る光変調デバイスによれば、可動部分に形成したミラーの変位によって光の反射方向を変化させる光変調デバイスであって、絶縁性薄膜で形成した可動部分の両面、または、片面に電気的に互いに絶縁分離された２つの電極を設け、電極間に静電力を作用させることによって可動部分を変形させてミラーを変位させるので、小型で、低消費電力化を図れるとともに、低コスト化を図れる。
【図面の簡単な説明】
【図１】本発明の液滴吐出ヘッドの第１実施形態に係るインクジェットヘッドの分解斜視説明図
【図２】同ヘッドの振動板長手方向の断面説明図
【図３】同ヘッドの振動板短手方向の要部拡大断面説明図
【図４】同ヘッドの電極配置パターンを説明する平面説明図
【図５】同ヘッドの作用説明に供する要部拡大断面説明図
【図６】同第２実施形態に係るインクジェットヘッドの振動板長手方向に沿う断面説明図
【図７】同ヘッドの振動板短手方向に沿う要部断面説明図
【図８】同第３実施形態に係るインクジェットヘッドの振動板長手方向に沿う断面説明図
【図９】同ヘッドの振動板短手方向に沿う要部断面説明図
【図１０】同第４、第５実施形態に係るインクジェットヘッドの振動板長手方向に沿う断面説明図
【図１１】同ヘッドの振動板短手方向に沿う要部断面説明図
【図１２】同実施形態に係るインクジェットヘッドの他の例を示す振動板短手方向に沿う要部断面説明図
【図１３】同実施形態に係るインクジェットヘッドの更に他の例を示す振動板短手方向に沿う要部断面説明図
【図１４】同実施形態に係るインクジェットヘッドの製造工程の一例を説明する説明図
【図１５】図１４に続く工程を説明する説明図
【図１６】図１５に続く工程を説明する説明図
【図１７】同第６実施形態に係るインクジェットヘッドの振動板長手方向に沿う断面説明図
【図１８】同ヘッドの振動板短手方向に沿う要部断面説明図
【図１９】同第７実施形態に係るインクジェットヘッドの振動板長手方向に沿う断面説明図
【図２０】同ヘッドの振動板短手方向に沿う要部断面説明図
【図２１】同第８実施形態に係るインクジェットヘッドの振動板長手方向に沿う断面説明図
【図２２】同ヘッドの振動板短手方向に沿う要部断面説明図
【図２３】同第９実施形態に係るインクジェットヘッドをその製造工程とともに説明する振動板短手方向に沿う断面説明図
【図２４】図２３に続く工程を説明する説明図
【図２５】同第１０実施形態に係るインクジェットヘッドの振動板短手方向に沿う断面説明図
【図２６】同第１１実施形態に係るインクジェットヘッドの振動板短手方向に沿う断面説明図
【図２７】同第１２実施形態に係るインクジェットヘッドをその製造工程とともに説明する振動板短手方向に沿う断面説明図
【図２８】図２７に続く工程を説明する説明図
【図２９】同第１３実施形態に係るインクジェットヘッドの振動板短手方向に沿う断面説明図
【図３０】同ヘッドの電極部分の拡大説明図
【図３１】同第１４実施形態に係るインクジェットヘッドの振動板短手方向に沿う断面説明図
【図３２】同ヘッドの作用説明に供する説明図
【図３３】同第１５実施形態に係るインクジェットヘッドの振動板短手方向に沿う要部拡大断面説明図
【図３４】同第１６実施形態に係るインクジェットヘッドの振動板短手方向に沿う要部拡大断面説明図
【図３５】同第１７実施形態に係るインクジェットヘッドの振動板短手方向に沿う要部拡大断面説明図
【図３６】本発明に係るインクカートリッジの説明に供する斜視説明図
【図３７】本発明に係るインクジェット記録装置の一例を説明する斜視説明図
【図３８】同記録装置の機構部の説明図
【図３９】本発明に係るマイクロポンプの実施形態を説明する断面説明図
【図４０】本発明に係る光学デバイスの実施形態を説明する断面説明図
【図４１】同光学デバイスを用いた光変調デバイスの一例を説明する斜視説明図
【図４２】同光変調デバイスの要部斜視説明図
【符号の説明】
１…第１基板、２…第２基板、３…ノズル板、４…ノズル孔、６…吐出室、７…流体抵抗部、８…共通液室、１０、２０、５０、６０、７０、９０、１００、１１０…振動板、１４…電極、１５４…固定電極、１５５…可動電極、２００…インクカートリッジ、３０１…流路基板、３０３…流路、３０５…可動部分、３０７…電極、４０１…ミラー、４０５…可動部分、４０７…電極。[0001]
[Industrial application fields]
  The present invention relates to a droplet discharge head, an ink cartridge, an ink jet recording apparatus, a microactuator, a micropump, and an optical device., Image forming apparatus, and apparatus for ejecting liquid dropletsAbout.
[0002]
[Prior art]
An ink jet head, which is a liquid droplet ejection head used in an image recording apparatus such as a printer, a facsimile machine, a copying apparatus, or the like or an image forming apparatus, has a single or a plurality of nozzle holes for ejecting ink droplets, and the nozzle holes. A discharge chamber (also referred to as an ink chamber, a liquid chamber, a pressurized liquid chamber, a pressure chamber, an ink flow path, etc.) communicating with the pressure chamber, and a pressure generating means for generating a pressure for pressurizing the ink in the discharge chamber. Ink droplets are ejected from the nozzle holes by pressurizing the ink in the ejection chamber with the pressure generated by the pressure generating means.
[0003]
Examples of the droplet discharge head include a droplet discharge head that discharges a liquid resist as a droplet, and a droplet discharge head that discharges a DNA sample as a droplet. The following description will focus on an inkjet head. . Also, microactuators constituting the actuator part of the droplet discharge head, for example, optical devices such as micropumps and micro light modulation devices, micro switches (micro relays), actuators for multi optical lenses (optical switches), micro flow meters, pressures It can also be applied to sensors and the like.
[0004]
By the way, as a droplet discharge head, a piezoelectric type that discharges ink droplets by deforming and displacing a vibration plate forming a wall surface of a discharge chamber using an electromechanical conversion element such as a piezoelectric element as pressure generating means. A bubble type (thermal type) that discharges ink droplets by generating bubbles by boiling an ink film using an electrothermal conversion element such as a heating resistor disposed in the discharge, and forming the wall surface of the discharge chamber There is an electrostatic type that ejects ink droplets by deforming a diaphragm with an electrostatic force.
[0005]
In recent years, bubble-type and electrostatic types that are lead-free have attracted attention due to environmental problems, and in addition to lead-free, a plurality of electrostatic types that have little influence on the environment from the viewpoint of low power consumption have been proposed.
[0006]
Some of these electrostatic heads are driven by a pushing method in which ink droplets are ejected by pushing the vibration plate into the ink chamber side to reduce the internal volume of the ink chamber, and the vibration plate in the direction outside the ink chamber. Some of them are driven by a striking method in which ink droplets are ejected by returning the displacement of the diaphragm so that the inner volume of the ink chamber is expanded from the state in which the inner volume is expanded by the force of.
[0007]
As a press-type electrostatic head, for example, as described in Japanese Patent Application Laid-Open No. 2-266944, ink is filled between a pair of electrodes, and one or both electrodes are diaphragms. In some cases, electrostatic attraction works between the electrodes by applying a voltage between the electrodes, and the electrodes (vibrating plates) are deformed, thereby ejecting and ejecting ink. Further, as described in Japanese Patent Application Laid-Open No. 2000-15805, a protrusion is provided on the surface of a diaphragm made of a silicon substrate, an electrode is formed on the protrusion, and a voltage is applied to the electrodes, thereby providing a gap between the protrusions. In some cases, the diaphragm is deformed by an electrostatic force acting on the ink, and ink is ejected.
[0008]
For example, as described in JP-A-6-71882, a pair of electrode pairs are provided via an air gap, and one electrode functions as a diaphragm, and the diaphragm is opposed to the diaphragm. An ink chamber filled with ink is formed on the opposite side of the electrode to be applied. By applying a voltage between the electrodes (between the diaphragm and the electrode), an electrostatic attractive force acts between the electrodes, and the electrode (the diaphragm) is deformed. In some cases, when the voltage is removed, the diaphragm returns to its original state by an elastic force, and ink is ejected using the force. Further, as described in Japanese Patent Application Laid-Open No. 2001-47624, a vibration plate is provided on one side of an electrode pair which is formed in a comb shape and is nested, and a voltage is applied to the electrode pair so In some cases, an electrostatic force is generated at the same time, the diaphragm is deformed by the displacement of the electrode, and ink is ejected by the elastic force of the diaphragm when the voltage is turned off.
[0009]
[Problems to be solved by the invention]
However, in the liquid droplet ejection head described in Japanese Patent Application Laid-Open No. 2-26643, the distance between the electrodes is inevitably increased because the ink is filled between the electrodes. Since the electrostatic force acting between the electrodes is inversely proportional to the square of the distance between the electrodes, there is a problem that the required voltage becomes very large as the distance between the electrodes increases. In this case, the voltage can be lowered to some extent depending on the dielectric constant of the ink, but it is not very effective because the influence of the distance between the electrodes is large. In addition, the degree of freedom of the ink is reduced because the dielectric constant of the ink needs to be increased or an electric field is applied to the ink. For this reason, there is a problem in that it is difficult to improve image quality due to restrictions on ink physical properties such as ink color, pH, and viscosity.
[0010]
Further, in the liquid droplet ejection head described in JP-A-6-71882, ink is not filled between the electrodes, so there are few restrictions on the ink and it is advantageous for high image quality. However, in order to reduce the voltage, the air gap between the electrodes must be made very small. It is very difficult to form such a small gap with high accuracy and little variation, and the yield does not increase. There is a problem. In addition, since the ink is ejected by the elastic force of the diaphragm, it is a so-called striking method. Therefore, the diaphragm needs to be rigid enough to eject ink, and the voltage is used to attract such a rigid diaphragm with electrostatic force. There is a problem that becomes high.
[0011]
Further, in the droplet discharge head described in Japanese Patent Laid-Open No. 2001-47624, since the comb-like electrode is used, the displacement can be increased, but the generated force is very small and the ink is discharged. If you try to get enough power to generate, the voltage will be very high. Moreover, since the structure is complicated, it is difficult to manufacture, and there is a problem that the cost becomes high.
[0012]
Further, in the droplet discharge head described in Japanese Patent Laid-Open No. 2000-15805, a protrusion is provided on a diaphragm formed of a conductive silicon substrate, and an electrode of a conductive member is formed on the protrusion. Therefore, there is a problem that the electrodes have the same potential through the silicon diaphragm and no electrostatic force is generated, and the diaphragm cannot be deformed. Moreover, it is necessary to form a protrusion on the diaphragm and attach an electrode to this protrusion, and it is difficult to attach an electrode to the surface of such a three-dimensional microstructure, and there is a portion where the electrode is not well formed. There is a problem that the production cannot be stably performed and the yield is poor due to variations or variations. Furthermore, in order to reduce the voltage, the interval between the protrusions must be narrowed. However, it is difficult to form an electrode in such a narrow interval, and if an electrode is formed between the narrow protrusions, a short circuit occurs. Defects that occur may occur. In addition, it is impossible to form electrodes on the protrusions by a general method because a photolithographic process with a three-dimensional structure is difficult to perform resist coating, exposure, etc. There is a problem that the manufacturing process becomes long and the cost becomes high.
[0013]
  The present invention has been made in view of the above problems, and is a low-cost, high-efficiency droplet-discharging head capable of high-quality printing, an ink cartridge that integrates this head, and high-quality recording. Inkjet recording device, low cost, high driving efficiency microactuator, micropump, optical device, Image forming device capable of high-quality recording, device for ejecting droplets with high droplet ejection efficiencyThe purpose is to provide.
[0014]
[Means for Solving the Problems]
In order to solve the above-described problems, a liquid droplet ejection head according to the present invention is formed from a conductive structure that is electrically insulated and separated from both surfaces of a diaphragm formed of an insulating thin film or one surface. The diaphragm is deformed by providing at least two electrodes and generating an electrostatic force between the electrodes.
[0015]
  In addition, the droplet discharge head according to the present invention is provided with at least one electrode made of a conductive structure on both surfaces of the diaphragm formed of an insulating thin film or on one surface,Wall part to fix the diaphragmAn electrode that is opposed to the electrode at a predetermined interval is provided, and the diaphragm is deformed by generating an electrostatic force between the electrodes.Is a thing.
[0016]
In these droplet discharge heads according to the present invention, the insulating thin film forming the vibration plate is preferably a laminated film of insulating films. In addition, the insulating thin film forming the diaphragm preferably has a tensile stress. In this case, the insulating film having the tensile stress is a silicon nitride film, and the thickness of the silicon nitride film is It is preferable that it is in the range of 10 nm to 900 nm, and that the silicon nitride film contains impurity atoms.
[0017]
The insulating thin film forming the diaphragm is preferably an organic resin film, and the organic resin film is preferably a polyimide film.
[0018]
The droplet discharge head according to the present invention is electrically insulated and separated from the surface of the insulating thin film of the diaphragm formed of a laminated film of silicon and an insulating thin film provided on the surface opposite to the silicon discharge chamber. The diaphragm is deformed by providing at least two electrodes made of a conductive structure and generating an electrostatic force between the electrodes.
[0019]
  Further, the droplet discharge head according to the present invention has a structure having conductivity on the surface of the insulating thin film of the diaphragm formed of a laminated film of silicon and an insulating thin film provided on the surface opposite to the silicon discharge chamber. Providing at least one electrode of the body,Wall part to fix the diaphragmAn electrode facing the electrode at a predetermined interval is provided, and the diaphragm is deformed by generating an electrostatic force between the electrodes.
[0020]
In the droplet discharge head according to each of the present inventions, it is preferable that the silicon of the vibration plate contains n-type or p-type impurity atoms.
[0021]
The droplet discharge head according to the present invention has a conductive structure in which both sides of a diaphragm formed of a main layer and a film having selectivity with respect to silicon etching, or one surface is electrically insulated and separated from each other. The diaphragm is deformed by providing at least two electrodes composed of a body and generating an electrostatic force between the electrodes.
[0022]
  In addition, the droplet discharge head according to the present invention includes a main layer and a film having selectivity with respect to silicon etching.Consisting ofWhile providing at least one electrode made of a conductive structure on both surfaces of the diaphragm or one surface,Wall part to fix the diaphragmAn electrode facing the electrode at a predetermined interval is provided, and the diaphragm is deformed by generating an electrostatic force between the electrodes.
[0023]
Furthermore, the liquid droplet ejection head according to the present invention includes a film having etching selectivity with respect to silicon etching / a main layer / both surfaces of a diaphragm formed with a film having selectivity with respect to etching of an electrode material, or one side. The diaphragm is deformed by providing at least two electrodes made of electrically conductive structures that are electrically insulated and separated from each other, and generating an electrostatic force between the electrodes.
[0024]
  Furthermore, the droplet discharge head according to the present invention includes a film having etching selectivity with respect to silicon etching / a main layer / film having selectivity with respect to etching of an electrode material.Consisting ofWhile providing at least one electrode made of a conductive structure on both surfaces of the diaphragm or one surface,Wall part to fix the diaphragmAn electrode facing the electrode at a predetermined interval is provided, and the diaphragm is deformed by generating an electrostatic force between the electrodes.
[0025]
In each of the droplet discharge heads according to the present invention, the film having etching selectivity with respect to silicon etching is preferably a silicon oxide film or a laminated film of a silicon nitride film and a silicon oxide film. The film having etching selectivity with respect to the etching of the electrode material is preferably a silicon oxide film. Furthermore, it is preferable that the main layer has a tensile stress.
[0026]
The main layer is preferably a silicon nitride film or silicon. Further, the thickness of the diaphragm is preferably 5 μm or less.
[0027]
The ink cartridge according to the present invention is obtained by integrating the droplet discharge head according to the present invention that discharges ink droplets and an ink tank that supplies ink to the droplet discharge head.
[0028]
  In the ink jet recording apparatus according to the present invention, the ink jet head for ejecting ink droplets is the liquid droplet ejecting head or the ink cartridge according to the present invention.
  The image forming apparatus and the apparatus for ejecting droplets according to the present invention include the droplet ejection head according to the present invention.
[0029]
The microactuator according to the present invention is provided with at least two electrodes composed of electrically conductive structures that are electrically insulated and separated from each other on one side or both sides of a movable part formed of an insulating thin film. The movable part is deformed by generating an electrostatic force.
[0030]
  The microactuator according to the present invention is an insulating thin film.Consist ofWhile providing at least one electrode made of a conductive structure on both sides of the movable part or one side,Wall part to fix the movable partAn electrode facing the electrode of the movable part with a predetermined interval is provided, and the movable part is deformed by generating an electrostatic force between the electrodes.
[0031]
The micropump according to the present invention is a micropump for transporting a liquid by deformation of a movable part, and two of the movable part formed of an insulating thin film and electrically insulated and separated from each other on one side. The movable part is deformed by providing an electrode and generating an electrostatic force between the electrodes.
[0032]
The optical device according to the present invention is an optical device that changes the reflection direction of light by displacement of a mirror formed on a movable part, and is electrically insulated from both sides or one side of the movable part formed of an insulating thin film. The two separated electrodes are provided, and the movable part is deformed by generating an electrostatic force between the electrodes.
[0033]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is an exploded perspective view of the ink jet head according to the first embodiment of the droplet discharge head of the present invention, and is a partial cross-sectional view. 2 is a sectional explanatory view of the head in the longitudinal direction of the diaphragm, FIG. 3 is a sectional explanatory view of the head in the lateral direction of the diaphragm, and FIG. 4 is an explanatory plan view showing an electrode arrangement pattern of the head.
[0034]
This ink jet head is of a side shooter type that discharges ink droplets from nozzle holes provided on the surface of the substrate, and includes three first, second, and third substrates 1 having the structure described in detail below. A plurality of nozzle holes 4 for discharging ink droplets, a discharge chamber 6 in which each nozzle hole 4 communicates, and each discharge chamber 6 via a fluid resistance portion 7 A common liquid chamber (common ink chamber) 8 for supplying the liquid is formed.
[0035]
The intermediate first substrate 1 is made of a silicon substrate and has a through portion for forming the discharge chamber 6 and a through portion for forming a common liquid chamber 8 for supplying ink to each discharge chamber 6. The diaphragm 10 formed of an insulating thin film that also serves as the bottom wall of the discharge chamber 6 and the common liquid chamber 8 is joined to the bottom surface of the first substrate 1.
[0036]
The insulating thin film forming the diaphragm 10 is formed of a silicon nitride film 10A which is an insulating film having a tensile stress. The thickness of the silicon nitride film 10A is in the range of 10 nm to 900 nm. By setting it within this range, the diaphragm 10 can be driven at a low voltage (deform the diaphragm 10) while ensuring sufficient rigidity.
[0037]
Impurity atoms are introduced into the silicon nitride film 10A. Here, the impurity atoms are introduced in order to relax the stress while maintaining the tensile stress of the silicon nitride film 10A. This atom introduction method was examined using various atom introduction methods such as thermal diffusion method and ion implantation method. Among them, the stress controllability is best when impurity atoms are introduced by the ion implantation method. It could be confirmed.
[0038]
Therefore, in this embodiment, by using the ion implantation method, boron atoms are implanted with an energy of 50 kev and a dose of 1E15 cm.^-2The silicon nitride film 10A having a tensile stress was formed. It was confirmed that the bending deformation of the vibration plate 10 due to the buckling does not occur by using the nitride film 10A having a tensile stress. As impurity atoms introduced into the silicon nitride film 10A, phosphorus atoms, arsenic atoms, hydrogen atoms, and the like can be used in addition to boron atoms.
[0039]
Further, when the discharge chamber 6 or the like is formed by using anisotropic etching of silicon with the silicon nitride film 10A provided on the first substrate 1, the silicon nitride film 10A has etching selectivity and is not damaged. Was confirmed. Furthermore, it was confirmed that by setting the thickness of the diaphragm 10 to 150 nm, sufficient rigidity was obtained even when the diaphragm 10 was miniaturized to 300 dpi or 600 dpi, and both the droplet discharge speed and the discharge amount were discharged with a sufficient margin.
[0040]
A plurality of conductive electrodes 14 are formed at predetermined intervals on the lower surface (surface) of the diaphragm 10 made of an insulating thin film composed of this single-layer insulating film, and the diaphragm 10 and each electrode 14 Are electrically separated from each other, and two adjacent electrodes (which are relatively referred to as electrodes 14a and 14b) of each electrode 14 are electrically separated from each other. Here, the electrode 14 is formed of, for example, polysilicon or single crystal silicon. The diaphragm 10 and the plurality of electrodes 14 constitute a microactuator according to the present invention that deforms the diaphragm 10 that is a movable part.
[0041]
Here, FIG. 4 shows an example of an electrode arrangement pattern for one diaphragm when viewed from the electrode 14 side of the first substrate 1. As shown in the figure, drive voltages (voltages of different potentials) are applied to adjacent electrodes 14a and 14b that are electrically separated from each other from a drive circuit 15 (shown here as a transmission circuit). It has come to be.
[0042]
The second substrate 2 bonded to the lower surface of the first substrate 1 is a protective substrate for protecting the electrode 14 from external impacts and dust, and reinforcing the strength of the first substrate 1. For the second substrate 2, a substrate made of glass, metal, silicon, resin, or the like is used. A concave portion 16 having a depth of 1 mm, for example, is formed on the substrate 2 at a position corresponding to each vibration plate 10. Yes. However, it is not always necessary to form the concave portion 16 for each diaphragm 10, and a configuration in which a concave portion surrounding the diaphragm array or a concave portion joined only to the edge of the chip may be formed.
[0043]
Further, as the third substrate 3 bonded to the upper surface of the first substrate 1, for example, a nickel substrate having a thickness of 50 μm is used, and the nozzle hole 4, A groove serving as a fluid resistance portion 7 for communicating the common liquid chamber 8 and the discharge chamber 6 is provided, and an ink supply port 9 is provided so as to communicate with the common liquid chamber 8.
[0044]
The operation of the ink jet head configured as described above will be described. For example, in the configuration of FIG. 4, when a pulse potential of 0V to 40V is applied to the electrode 14a by the oscillation circuit 15, the surface of the electrode 14a is positively charged, and between the adjacent electrodes 14b to which no pulse potential is applied, As shown in FIG. 5, an electrostatic force is generated, an electrostatic attraction action works, the free ends of the electrodes 14 (the diaphragm 10 side is a fixed end) are attracted, and the electrodes 14 are displaced, and the free ends of these electrodes 14 When the side is displaced, the diaphragm 10 which is the fixed end side of the electrode 14 bends upward. As a result, the pressure in the discharge chamber 6 increases rapidly, and the ink droplets 22 are discharged from the nozzle holes 4 toward the recording paper 23 as shown in FIG.
[0045]
When the potential of the electrode 14a returns to 0V, there is no potential difference with the electrode 14b, and the diaphragm 10 is restored to the original state. When the diaphragm 10 is restored, ink is supplied from the common liquid chamber 8 into the discharge chamber 6 through the fluid resistance portion 7. In other words, in this embodiment, ink droplets are ejected by the pushing method.
[0046]
Here, the force F acting between the electrodes increases in inverse proportion to the square of the distance d between the electrodes as shown in the following equation (1). In order to drive at a low voltage, it is important to narrow the gap between the electrodes 14a and 14b, that is, the groove between the electrodes 14.
[0047]
[Expression 1]

[0048]
In the equation (1), F: force acting between electrodes, ε: dielectric constant, S: area of opposing surfaces of electrodes, d: distance between electrodes, and V: applied voltage.
[0049]
As described above, in this inkjet head, the electrodes 14 that are electrically separated and independent from each other are provided on one surface of the diaphragm 10 formed of an insulating thin film, and a potential difference is generated between the electrodes 14a and 14b facing each other. By applying the generated voltage, an electrostatic attractive force is generated between the adjacent electrode 14a and the electrode 14b, and a large displacement of the diaphragm 10 can be obtained by a slight displacement of the electrode 14, thereby improving the droplet discharge efficiency. In addition, high-quality recording becomes possible.
[0050]
In the microactuator of this head, the structure itself provided on the vibration plate 10 functions as the electrode 14, so that a difficult process of forming the electrode on the silicon structure by a method such as film formation as before is necessary. Therefore, it is possible to reduce the cost, and it is possible to reduce defects such as a short circuit caused by forming electrodes at very narrow intervals between structures. Further, there is no need for a process of separating the electrodes into comb-like shapes after forming the electrodes on the structure, and cost reduction and mass production are easy.
[0051]
Furthermore, since the diaphragm 10 is made of an insulating thin film and is electrically separated from the diaphragm 10 and the electrode 14, all the electrodes can be connected via the silicon diaphragm even when voltage is applied to the electrodes as in the prior art. The voltage can be efficiently applied to the electrode 14 without causing malfunction due to the same potential and without the voltage applied to the electrode 14 leaking to the diaphragm 10 side. Further, since the diaphragm 10 is insulative and insulated from the electrode 14, the driving voltage is not applied to the liquid (here, ink), and the liquid by electrolysis when the driving thickness is applied. Therefore, the reliability is improved and high-quality recording is possible.
[0052]
Next, an inkjet head according to a second embodiment of the present invention will be described with reference to FIGS. FIG. 6 is a cross-sectional explanatory view of the head in the longitudinal direction of the diaphragm, and FIG. 7 is a cross-sectional explanatory view of the head in the lateral direction of the diaphragm.
In this embodiment, a polyimide film 10B, which is an organic resin film having a tensile stress and having an insulating property, is used as the insulating thin film forming the diaphragm 10. The film thickness of this polyimide film 10B was 3 μm.
[0053]
In this way, by forming the diaphragm 10 with the tensile stress polyimide film 10B, the diaphragm 10 was not deformed by buckling, and the diaphragm 10 could be formed. Further, since the Young's modulus is small, it can be formed with a thickness of 3 μm. Furthermore, since the polyimide (organic resin material) forming the diaphragm 10 is excellent in corrosion resistance against liquids, it does not elute even in liquids having various alkaline and acidic chemical properties, and is sufficiently reliable. The liquid droplets can be discharged with good performance.
[0054]
Next, an inkjet head according to a third embodiment of the present invention will be described with reference to FIGS. FIG. 8 is a cross-sectional explanatory view of the head in the longitudinal direction of the diaphragm, and FIG. 9 is a cross-sectional explanatory view of the head in the lateral direction of the diaphragm.
In this embodiment, the diaphragm 10 having an insulating property is constituted by a laminated film of insulating thin films. That is, the diaphragm 10 is formed of a laminated film of a silicon nitride film 10A that is an insulating film having tensile stress and a silicon oxide film 10C that is a film having compressive stress.
[0055]
Here, the silicon nitride film 10A has a thickness of 150 nm, and the silicon oxide film 10C has a thickness of 150 nm. Further, in order to relax the stress while maintaining the tensile stress of the silicon nitride film 10A, phosphorus atoms as impurity atoms were introduced from the result of the first embodiment by the ion implantation method.
[0056]
Thus, the diaphragm 10 is formed of an insulating thin film that is a laminated film of insulating films, and in particular, a laminated film of a tensile stress film (here, a silicon nitride film) and a compressive stress film (here, a silicon oxide film). Thus, by independently controlling different internal stresses of each film, it is possible to prevent bending deformation due to the bending of the diaphragm 10.
[0057]
When the discharge chamber 6 is formed by using anisotropic etching of silicon, the silicon nitride film 10A functions as an etching stopper, so that the diaphragm 10 is not damaged. Further, by setting the thickness of the silicon oxide film 10C to 150 nm and the thickness of the silicon nitride film 10A to 150 nm, sufficient rigidity can be obtained even when the silicon oxide film 10C is miniaturized to 300 dpi or 600 dpi, and both the droplet discharge speed and the discharge amount are obtained. It was confirmed that the ink was discharged with a sufficient margin. Furthermore, since it is a laminated diaphragm of the silicon nitride film 10A and the silicon oxide film 10B, the generation of pinholes can be prevented.
[0058]
Next, an inkjet head according to a fourth embodiment of the present invention will be described with reference to FIGS. FIG. 10 is a sectional explanatory view of the head in the longitudinal direction of the diaphragm, and FIG. 11 is a sectional explanatory view of the head in the lateral direction of the diaphragm.
In this embodiment, the diaphragm 20 is a laminated film of a silicon film, which is a main layer and also a conductive film, and an insulating film. That is, the diaphragm 20 is formed by a silicon film 20A which is a main layer and a silicon oxide film 20B which is an insulating thin film formed on the surface (electrode side surface) opposite to the discharge chamber 6 of the silicon film 20A. A plurality of electrodes 14 are provided on the surface of the film 20B.
[0059]
Here, the silicon film 20A is formed of 1E20 / cm of boron atoms up to a depth of 0.5 μm on the silicon substrate forming the first substrate 1.^ThreeThis is a high-concentration boron diffusion layer containing a single layer. We studied thermal diffusion methods such as coating diffusion method and vapor phase diffusion method and ion implantation method as boron atom introduction method, but ion implantation method has the best control of diffusion depth that determines silicon film thickness. It was confirmed. Therefore, here, boron atoms are introduced by ion implantation using ion implantation. Since the film thickness of the silicon film 20A was controlled by the diffusion depth in which boron atoms were introduced by the ion implantation method, the silicon film 20A could be formed with high precision to the silicon thickness as designed.
[0060]
Here, when the main layer of the diaphragm is formed of silicon, by setting the thickness to 5 μm or less, it is possible to perform low-voltage driving while ensuring the rigidity of the diaphragm.
[0061]
In addition, even if the main layer of the diaphragm 20 is the conductive silicon film 20A, a silicon oxide film 20B that is an insulating thin film is formed, and a plurality of electrodes 14 are formed on the surface of the silicon oxide film 20B. The silicon film 20A and the electrode 14 are electrically isolated from each other, and when a driving voltage is applied to the electrode 14, each electrode is formed to form an electrode film on the convex portion of the silicon diaphragm as before. There is no inconvenience that the voltage is substantially the same, and the voltage applied to the electrode 14 can be applied without leaking to the silicon film 20A, and efficient driving can be performed.
[0062]
Next, an inkjet head according to a fifth embodiment of the invention will be described. Since this embodiment is obtained by changing the atoms implanted into the silicon film 20A of the fourth embodiment, it will be described with reference to FIGS.
That is, in this embodiment, the silicon film 20A, which is the main layer of the vibration plate 20, has a phosphorus atom of 1E20 / cm up to a depth of 0.5 μm in the silicon substrate by ion implantation.^ThreeThe discharge chamber 6 is formed at the same time as the discharge chamber 6 using the electrochemical etching method. Since the film thickness of the silicon film 20A is controlled by the diffusion depth of phosphorus atoms introduced by the ion implantation method, it is possible to form a silicon thickness with high accuracy as designed.
[0063]
Similarly to the fourth embodiment, even if the main layer of the diaphragm 20 is the conductive silicon film 20A, a silicon oxide film 20B which is an insulating thin film is formed, and the surface of the silicon oxide film 20B is formed. Since the electrode 14 is provided on the electrode 14, the silicon film 20A and the electrode 14 are electrically insulated and separated. When a drive voltage is applied to the electrode 14, the electrode film is formed on the convex portion of the diaphragm made of a silicon substrate as before. There is no inconvenience that the electrodes have substantially the same potential for formation, and the voltage applied to the electrodes 14 can be applied without leaking to the silicon film 20A, and efficient driving can be performed.
[0064]
Next, an inkjet head according to another example of the fourth and fifth embodiments will be described with reference to FIG. In addition, the figure is a cross-sectional explanatory drawing along the diaphragm lateral direction of the head.
In this example, a spacer 25 that is a layer or a structure of the same material as the electrode 14 is formed in a substantially same plane as a surface on which the electrode 14 is formed in a region other than the diaphragm 20. The spacer 25 can be formed at the same time as the electrode 14 and can be formed without removing the electrode material other than the diaphragm region.
[0065]
By providing such a spacer 25, it is possible to protect the electrode 14 which is a minute structure in the process before the first substrate 1 is bonded to the second substrate 2, and in the manufacturing process, the wafer is transported or during the process. Defects due to breakage of the electrode 14 can be reduced.
[0066]
Next, an inkjet head according to still another example of the fourth and fifth embodiments will be described with reference to FIG. In addition, the figure is a cross-sectional explanatory drawing along the diaphragm lateral direction of the head.
In this example, a spacer 25 that is a layer or a structure of the same material as the electrode 14 is formed in substantially the same plane as the surface on which the electrode 14 is formed in a region other than the diaphragm 20, and the thickness of the spacer 25 is set to the electrode 14 is formed thicker than 14. In this case, the 2nd board | substrate 2 can use a flat plate board as it is, and it becomes unnecessary to form a recessed part.
[0067]
By adopting such a structure, the electrode 14 is less likely to come into contact with the spacer 25 and be damaged as compared with the second embodiment, and defects due to electrode breakage can be reduced. In addition, when a protective substrate (second substrate 2) is bonded under the first substrate 1, there is also an advantage that it is not necessary to form a recess in the protective substrate.
[0068]
Here, an inkjet head manufacturing process according to another example of the fourth and fifth embodiments will be described with reference to FIGS.
Here, the electrode 14 is formed of single crystal silicon. The silicon film 20A, which is the main film forming the diaphragm 20, is a high-concentration p-type impurity layer, and the high-concentration p-type impurity layer is as thick as a desired diaphragm thickness. 0 μm.
[0069]
That is, as shown in FIG. 14A, boron or phosphorus is diffused by ion implantation into a silicon substrate 41 having a thickness of (110) serving as the first substrate 1 and having a surface orientation of (110) to form the silicon film 20A. A high-concentration boron diffusion layer or a high-concentration phosphorus diffusion layer (these are referred to as “high-concentration impurity diffusion layers”) 42 is formed. Here, a high concentration impurity diffusion layer 42 having a depth of 1.0 μm is formed.
[0070]
When the high concentration impurity diffusion layer 42 is a high concentration boron diffusion layer, a compound layer of silicon and boron is formed on the surface of the diffusion layer. To remove this layer, the compound layer is thermally oxidized. It can be removed by etching with a hydrofluoric acid-based etching solution. Further, the surface where boron or phosphorus is diffused in silicon is roughened, and a strong bond may not be obtained by subsequent direct bonding. For this purpose, the diffusion surface is polished to form a smooth surface. Further, as the substrate to be the first substrate 1, a (100) -oriented silicon substrate may be used instead of the (110) -oriented silicon substrate.
[0071]
Next, as shown in FIG. 2B, after removing the compound layer and polishing, a thermal oxide film 43 to be the silicon oxide film 20B is formed with a thickness of 50 nm by wet oxidation at 900 ° C./5 minutes. Here, as a method for forming an oxide film, there are plasma CVD, sputtering, HTO, TEOS, and the like, but a thermal oxide film is preferable in terms of withstand voltage, defects, residual charge, durability, and the like.
[0072]
Then, as shown in FIG. 3C, another silicon substrate 44 for forming the electrode 14 is prepared, and this silicon substrate 44 is directly bonded to the high concentration impurity diffusion layer 42 side of the silicon substrate 41. Here, a silicon wafer having a (100) plane orientation was used as the silicon substrate 44. By bonding a silicon wafer having a good surface property and heating at a high temperature, the two wafers are firmly bonded. Here, heat treatment was performed at 1000 ° C./2 hours.
[0073]
Thereafter, as shown in FIG. 4D, the silicon substrate 44 is polished to a thickness of 20 μm which is the desired length (height) of the electrode 14.
[0074]
Next, as shown in FIG. 15A, a resist pattern is formed on the silicon substrate 44 polished by photolithography, and the silicon substrate 44 is etched by dry etching with a line width of 0.5 μm and a width of 0.5 μm. 14 and the spacer 25 are formed. The shape of the electrode 14 is, for example, a comb-teeth shape as shown in FIG. In the etching, the oxide film 43 becomes a stop layer. ICP is effective for dry etching because it is necessary to etch very deep grooves.
[0075]
Then, as shown in FIG. 2B, a silicon nitride film 46 which becomes a mask for potassium hydroxide etching is formed by LP-CVD. Thereafter, as shown in FIG. 2C, a resist pattern having a shape such as the discharge chamber 6 or the common liquid chamber 8 is obtained on the silicon nitride film 46, and the silicon nitride film 46 and the oxide film 43 in the opening of the resist are formed. Etching is removed by dry etching to remove the resist.
[0076]
Thereafter, as shown in FIG. 16A, when the high-concentration impurity diffusion layer 42 is a high-concentration boron diffusion layer, the silicon nitride film 46 and the oxide film 43 are formed with a 25 wt% potassium hydroxide aqueous solution at 80 ° C., for example. Etching is performed from the opening until just before the silicon substrate 41 reaches the high-concentration boron diffusion layer (about 10 μm remaining). Next, the etching solution is changed to a 30 wt% potassium hydroxide aqueous solution at 80 ° C. in which IPA is supersaturated, and etching is stopped spontaneously when the high concentration boron diffusion layer is reached.
[0077]
Here, a 25 wt% potassium hydroxide aqueous solution has a high etch rate and provides stable etching. In addition, a 30 wt% potassium hydroxide aqueous solution containing IPA has a high etching selection ratio between the silicon substrate and the high-concentration boron layer, and the etching can be stopped with high accuracy. Since IPA has a low boiling point and evaporates rapidly when heat is applied, it is preferable to attach a reflux device that cools the vapor to liquefy it and return it to the etching tank. As an etchant that can increase the etching selectivity of the high-concentration boron diffusion layer, other than IPA-added potassium hydroxide, a low-concentration potassium hydroxide solution or EDP of about 3 wt% to 10 wt% may be used.
[0078]
When the high-concentration impurity diffusion layer 42 is a high-concentration phosphorus diffusion layer, a reference electrode is placed in a 25 wt% potassium hydroxide aqueous solution at 80 ° C., and the reverse is provided between the base substrate and the high-concentration phosphorus diffusion layer. While applying a bias, electrochemical etching is performed using the openings of the silicon nitride film 46 and the oxide film 43 as a mask until the high concentration phosphorus diffusion layer is reached. Etching stops spontaneously at the depth of the high-concentration phosphorus diffusion layer by electrochemical etching
[0079]
Thereafter, as shown in FIG. 4B, the silicon nitride film 46 is removed by hot phosphoric acid, hydrofluoric acid, etc., and the thermal oxide film 43 is removed by hydrofluoric acid, etc. (the diaphragm portion remains). A silicon vibration plate 20 is formed which includes a high-concentration impurity diffusion layer 42 which is a 1 μm-thick silicon film 20A and a thermal oxide film 43 which is a silicon oxide film 20B forming the bottom wall of the discharge chamber 6.
[0080]
Here, since the electrode 14 is formed of single crystal silicon, the thickness (length) of the electrode 14 can be determined by polishing after wafer bonding, and a thick electrode that cannot be formed by film formation can be determined. Can be formed. If the electrode is thick (height is high), the diaphragm can be deformed with a small force and can be driven at a low voltage. Further, it is possible to integrate the drive circuit of the droplet discharge head by utilizing a region not used as an electrode of the bonded silicon wafer 44. Since the silicon wafer 44 is used for forming semiconductor elements, it is suitable for forming a drive circuit.
[0081]
In addition to ion implantation, the high-concentration boron diffusion layer or the high-concentration phosphorus diffusion layer can be formed by solid diffusion, coating diffusion, or an epitaxial layer doped with boron or phosphorus. Since ion implantation can form a shallow diffusion layer with high accuracy, it is suitable for forming a thin diaphragm. In addition, in the epitaxial layer, since a layer doped with boron or phosphorus is grown on the silicon substrate, the boundary between the high-concentration boron region or the high-concentration phosphorus region becomes clearer than solid diffusion, ion implantation, and coating diffusion, A sharp etching stop can be realized, and a more accurate diaphragm can be formed.
[0082]
As described above, when a semiconductor such as single crystal silicon (or polysilicon) is used for the electrode 14, the electrical resistance value of the electrode becomes a problem when high-frequency driving or multi-channel driving is performed. Sometimes. In this case, it is preferable to introduce impurity atoms having n-type or p-type conductivity, for example, phosphorus or arsenic for n-type, boron or antimony for p-type.
[0083]
Next, an inkjet head according to a sixth embodiment of the present invention will be described with reference to FIGS. FIG. 17 is a cross-sectional explanatory diagram of the head in the longitudinal direction of the diaphragm, and FIG. 18 is a cross-sectional explanatory diagram of the head in the lateral direction of the diaphragm.
In this embodiment, the diaphragm 50 includes a silicon oxide film 50A which is a film having etching selectivity with respect to silicon etching at the time of forming the liquid chamber, a silicon nitride film 50B having tensile stress which is a main layer, and the electrode 14. It is composed of a laminated film with a silicon oxide film 50C having etching selectivity with respect to silicon etching as an electrode material at the time of formation, and a plurality of electrodes 14 are provided on the surface of the silicon oxide film 50C.
[0084]
The silicon oxide film 50A has a thickness of 50 nm, the silicon nitride film 50B has a thickness of 150 nm, and the silicon oxide film 50C has a thickness of 50 nm. In order to relieve the stress while maintaining the tensile stress of the silicon nitride film 50B, phosphorus is also introduced here as an impurity atom by the ion implantation method.
[0085]
As described above, since the silicon substrate is used as the first substrate 1 and the silicon oxide films 50A and 50C having selectivity for the silicon etching at the time of forming the liquid chamber and the silicon etching of the electrode material are provided, vibration is generated during each etching process. Etching damage to the silicon nitride film 50B, which is the main layer of the plate 50, can be prevented, and the vibration plate 50 with higher accuracy can be formed. Further, since the silicon oxide film 50A acts as a corrosion-resistant film against the liquid, it is not necessary to form a new corrosion-resistant film and the process can be shortened.
[0086]
In addition, since the silicon nitride film 50B, which is the main layer of the diaphragm 50, has a tensile stress, no bending deformation due to buckling occurs and the electrostatic attractive force generated between the electrodes 14 and 14 is within the diaphragm plane. Can be reduced. Furthermore, since the silicon nitride film 50B is used as a part of the diaphragm 50 as a base, the effective rigidity can be improved, and even when a thinner diaphragm is used to reduce the size to 300 dpi or 600 dpi, the droplets can be reduced. Can be reliably and efficiently performed.
[0087]
Next, an inkjet head according to a seventh embodiment of the present invention will be described with reference to FIGS. 19 is a cross-sectional explanatory view of the head in the longitudinal direction of the diaphragm, and FIG. 20 is a cross-sectional explanatory view of the head in the short side of the diaphragm.
In this embodiment, the vibration plate 60 includes a laminated film of a silicon nitride film 60Aa and a silicon oxide film 60Ab as a film 60A having etching selectivity with respect to silicon etching at the time of forming a liquid chamber, and tensile stress as a main layer. And a silicon oxide film 60C having etching selectivity with respect to silicon etching as an electrode material when the electrode 14 is formed.
[0088]
Of the films 60A, the silicon nitride film 60Aa has a thickness of 50 nm, the silicon oxide film 60Ab has a thickness of 50 nm, and the main layer, the silicon nitride film 60B having tensile stress, has a thickness of 150 nm, and has etching selectivity. The thickness of the silicon oxide film 60C was 50 nm. Here, arsenic is introduced as impurity atoms by an ion implantation method in order to relieve the stress while maintaining the tensile stress of the silicon nitride film 60B as the main layer.
[0089]
As described above, the silicon nitride film 60Aa and the silicon oxide film 60Ab having selectivity for silicon etching and the silicon oxide film 60C having selectivity for silicon etching of the electrode material are provided at the time of silicon etching at the time of forming the liquid chamber. In each etching, the margin for etching damage to the silicon nitride film 60B, which is the main layer of the diaphragm 60, is improved as compared with the sixth embodiment. As a result, damage to the silicon nitride film 60B, which is the main layer of the diaphragm, does not occur at all, and a highly accurate diaphragm can be formed.
[0090]
In addition, since the silicon nitride film 60B, which is the main layer of the diaphragm 60, has a tensile stress, there is no bending deformation due to buckling, and within the diaphragm surface of the electrostatic attractive force generated between the electrodes 14 and 14. Can be reduced. Furthermore, since the silicon nitride film 60B is used as a part of the diaphragm 50 as a base, the effective rigidity can be improved, and the case where the thickness is reduced to 300 dpi and 600 dpi with a diaphragm thinner than that of silicon. In this case, the liquid droplets can be discharged efficiently and reliably.
[0091]
Next, an inkjet head according to an eighth embodiment of the invention will be described with reference to FIGS. 21 is a cross-sectional explanatory view of the head in the longitudinal direction of the diaphragm, and FIG. 22 is a cross-sectional explanatory view of the head in the lateral direction of the diaphragm.
In this embodiment, the diaphragm 70 is an electrode material when the silicon oxide film 70A having etching selectivity with respect to silicon etching at the time of forming the liquid chamber, the single crystal silicon thin film 7B as the main layer, and the electrode 14 are formed. It is composed of a laminated film with a silicon oxide film 7C having etching selectivity with respect to silicon etching.
[0092]
The silicon nitride film 70 has a thickness of 50 nm, the main layer single crystal silicon thin film 70B has a thickness of 0.5 μm, and the silicon oxide film 70C having etching selectivity has a thickness of 50 nm.
[0093]
As described above, since the silicon oxide films 70A and 70C having selectivity for the silicon etching at the time of forming the liquid chamber or the silicon etching of the electrode material are provided, the etching damage to the single crystal silicon thin film 70B which is the main layer at each etching step. Is not observed, and a highly accurate diaphragm can be formed. Further, since the silicon oxide film 70A acts as a corrosion resistant film against the liquid, it is not necessary to form a new corrosion resistant film, and the process can be shortened. Furthermore, since the single crystal silicon film 70B, which is the main layer of the diaphragm 70, has no crystal grain boundaries or crystal defects, the long-term reliability of the diaphragm can be sufficiently ensured.
[0094]
Next, an inkjet head according to a ninth embodiment of the invention will be described with reference to FIGS.
In this embodiment, the silicon film constituting the main layer is a polycrystalline silicon film, and the electrode 14 is formed of polysilicon (polycrystalline silicon). By forming the silicon film constituting the main layer from a polycrystalline silicon film, it can be formed by a CVD method, and the film thickness controllability is improved.
[0095]
That is, as shown in FIG. 23A, a silicon substrate 81 having a thickness of 400 μm with a plane orientation of (110) is used as a base substrate, and a silicon oxide film 82 is formed on the silicon substrate 81 with a thickness of 50 nm. A substrate 80 to be the first substrate 1 is prepared in which a polycrystalline silicon film 83 having a thickness of 1.0 μm is formed on the surface of the silicon oxide film 82.
[0096]
Here, in order to relieve internal stress, it is preferable to introduce boron or phosphorus atoms which are atoms of conductivity type of n-type or p-type into the polycrystalline silicon film 83. In this embodiment, boron atoms are introduced. Introduced. On the other hand, the silicon oxide film 82 is formed by a thermal oxidation method, a CVD method, a sputtering method, or the like. This silicon oxide film 82 is a film having etching selectivity when forming a silicon liquid chamber in a later step.
[0097]
Next, as shown in FIG. 2B, a silicon oxide film 84 is formed on the entire surface of the substrate 80 by the CVD method. Here, as a method for forming the silicon oxide film 84, there are plasma CVD, sputtering, HTO, and the like, but HTO is preferable in terms of withstand voltage and durability.
[0098]
Then, as shown in FIG. 2C, a polysilicon 85 for forming the electrode 14 is formed on the surface of the silicon oxide film 84 to a thickness of 5 μm, and the polysilicon layer on the upper surface is removed by etching.
[0099]
Thereafter, as shown in FIG. 4D, a resist pattern is formed on the polysilicon 85 by photolithography, and the polysilicon is etched by a dry etching to a line width of 1 μm and 0.5 μm, so that the electrode 14 and the above-described one are obtained. A spacer 25 is formed. At this time, since the silicon oxide film 84 forms an etching stop layer, damage to the polycrystalline silicon 83 which is the main layer of the diaphragm can be prevented. The electrode 14 was shaped like a comb as shown in FIG.
[0100]
Next, as shown in FIG. 24A, a silicon nitride film 86 serving as a mask for potassium hydroxide etching is formed on the entire surface by LP-CVD, and discharged onto the silicon nitride film 86 as shown in FIG. A resist pattern in the shape of a liquid chamber such as the chamber 6 or the common liquid chamber 8 is formed. Next, the silicon nitride film 86 and the silicon oxide film 83 in the opening of the resist are removed by dry etching, and the resist is removed. A mask pattern is formed.
[0101]
Thereafter, as shown in FIG. 2C, the openings of the silicon nitride film 86 and the silicon oxide film 83 are etched with a 25 wt% potassium hydroxide aqueous solution at 80 ° C. When the etching reaches the silicon oxide film 82, the silicon oxide film 82 is hardly etched, so that the etching damage to the polycrystalline silicon 83 which is the main layer of the vibration plate does not occur.
[0102]
Here, since the (110) plane silicon wafer is used for the base substrate 81, the (111) plane vertical wall is formed by anisotropic etching with potassium hydroxide. Since the vertical wall is obtained by using the (110) plane wafer, the discharge chambers 6 can be arranged with high density. Here, an aqueous potassium hydroxide solution is used as an etching solution, but an alkaline solution such as TMAH (tetramethylammonium hydroxide solution), EDP (ethylenediamine pyrocatechol), lithium hydroxide, or the like may be used.
[0103]
Thereafter, as shown in FIG. 4D, the silicon nitride film 86 is removed by hot phosphoric acid.
[0104]
In this way, the diaphragm 90 and the discharge chamber 6 composed of the laminated film of the silicon oxide film 82 having a thickness of 50 nm, the polycrystalline silicon film 83 having a thickness of 500 nm, and the silicon oxide film 83 having a thickness of 50 nm are completed.
[0105]
Next, an inkjet head according to a tenth embodiment of the invention will be described with reference to FIG. In addition, the figure is principal part cross-section explanatory drawing along the diaphragm short-side direction of the head.
In this embodiment, the diaphragm 100 is formed by a CVD method, which is a laminated film of a silicon nitride film 100Aa and a silicon oxide film 100Ab as a film 100A having etching selectivity with respect to silicon etching at the time of forming a liquid chamber, and a main layer. Is a laminated film composed of a polycrystalline silicon film 100B into which boron atoms have been introduced after being formed by the above process and a silicon oxide film 100C having etching selectivity with respect to silicon etching as an electrode material at the time of electrode formation.
[0106]
The film thickness of the silicon nitride film 100Aa as the film 100A having etching selectivity with respect to silicon etching at the time of forming the liquid chamber is 50 nm, and the film thickness of the silicon oxide film 100Ab is 50 nm. The introduced polycrystalline silicon film 100B has a thickness of 1.0 μm, and the silicon oxide film 100C has a thickness of 50 nm.
[0107]
As described above, the laminated film of the silicon nitride film 100Aa and the silicon oxide film 100Ab having selectivity for silicon etching at the time of silicon etching at the time of forming the liquid chamber, and the silicon oxide film 100C having selectivity for silicon etching of the electrode material are provided. Therefore, etching damage to the polycrystalline silicon film 100B does not occur at all during each etching step, and a highly accurate diaphragm can be formed.
[0108]
In addition, since the polycrystalline silicon film 100B is formed by the CVD method, a highly accurate diaphragm with good film thickness controllability can be formed. Furthermore, since the internal stress of the polycrystalline silicon film 100B can be controlled by incorporating boron into the polycrystalline silicon film 100B, a flat diaphragm without deflection can be realized and generated in the electrode pair (14, 14). It is possible to reduce the in-plane variation of electrostatic attraction.
[0109]
Next, an inkjet head according to an eleventh embodiment of the present invention will be described with reference to FIG. In addition, the figure is principal part cross-section explanatory drawing along the diaphragm short-side direction of the head.
In this embodiment, the diaphragm 110 is formed by a CVD method, which is a laminated film of a silicon nitride film 110Aa and a silicon oxide film 110Ab as a film 110A having etching selectivity with respect to silicon etching at the time of forming a liquid chamber, and a main layer. A silicon nitride film 110B into which boron atoms have been introduced after being formed by the above process, and a silicon oxide film 110C having etching selectivity with respect to silicon etching as an electrode material when forming the electrode.
[0110]
The film thickness of the silicon nitride film 110Aa as the film 110A having etching selectivity with respect to silicon etching at the time of forming the liquid chamber is 50 nm, and the film thickness of the silicon oxide film 110Ab is 50 nm. The introduced silicon nitride film 110B has a thickness of 150 nm, and the silicon oxide film 110C has a thickness of 50 nm.
[0111]
As described above, the silicon nitride film 110Aa and the silicon oxide film 110Ab having selectivity for silicon etching at the time of silicon etching at the time of forming the liquid chamber, and the silicon oxide film 110C having selectivity for silicon etching of the electrode material are provided. Therefore, etching damage to the silicon nitride film 110B does not occur at all during each etching step, and a highly accurate diaphragm can be formed.
[0112]
In addition, since the silicon nitride film 110B is formed by the CVD method, a highly accurate diaphragm with good film thickness controllability can be formed. Further, by incorporating boron into the silicon nitride film 110B, the internal stress of the silicon nitride 110B can be controlled to a tensile stress, so that a flat diaphragm without deflection can be realized and generated in the electrode pair (14, 14). The variation of the electrostatic attraction force on the diaphragm surface can be reduced.
[0113]
Next, an inkjet head according to a twelfth embodiment will be described with reference to FIGS.
First, as shown in FIG. 27A, a silicon substrate 121 having a surface orientation of (110) and having a thickness of 400 μm is used as a base substrate, and a thickness of 50 nm having selectivity for silicon etching at the time of forming a liquid chamber. A laminated film 122 of a silicon nitride film 122a and a silicon oxide film 122b with a thickness of 50 nm is formed, and a substrate 120 in which a silicon nitride film 123 with a thickness of 150 nm is formed on the laminated film 122 is prepared.
[0114]
Here, since it is preferable to introduce boron or phosphorus atoms in the silicon nitride film 123 in order to relieve internal stress while maintaining tensile stress, boron atoms are introduced by ion implantation. Further, the stacked film 122 of the silicon nitride film 122a and the silicon oxide film 122b is a film having etching selectivity when forming a silicon liquid chamber in a later step. Further, the silicon nitride films 123 and 122a and the silicon oxide film 122b are formed by a CVD method.
[0115]
Next, as shown in FIG. 2B, a silicon oxide film 124 is formed on the entire surface by a CVD method to a film thickness of 50 nm. Here, as a method for forming the silicon oxide film 124, there are plasma CVD, sputtering, HTO, and the like, but HTO is preferable in terms of withstand voltage and durability.
[0116]
Thereafter, as shown in FIG. 3C, a polysilicon layer 125 is formed to a thickness of 5 μm on the surface of the silicon nitride film 124, and the polysilicon layer 125 on the upper surface is removed by etching.
[0117]
Then, as shown in FIG. 4D, a resist pattern is formed on the polysilicon layer 125 by photolithography, and the polysilicon layer 125 is etched by dry etching with a line width of 1 μm and 0.55 μm to form electrodes 14 and spacers. 25 is formed. At this time, since the silicon oxide film 124 forms an etching stop layer, damage to the silicon nitride film 123 can be prevented. The shape of the electrode 14 was a comb shape as shown in FIG.
[0118]
Next, as shown in FIG. 28A, a silicon nitride film 126 serving as a mask for potassium hydroxide etching is formed on the entire surface by LP-CVD. Then, as shown in FIG. 5B, a resist pattern having a shape such as the discharge chamber 6 or the common liquid chamber 8 is formed on the silicon nitride film 126, and the silicon nitride film 126 and the silicon oxide film 124 in the opening of the resist are formed. Is removed by dry etching, the resist is removed, and a mask pattern is formed.
[0119]
Thereafter, as shown in FIG. 2C, the openings of the silicon nitride film 126 and the silicon oxide film 124 are etched with a 25 wt% potassium hydroxide aqueous solution at 80 ° C. At this time, etching was stopped on the silicon nitride film 122a, and the silicon oxide film 122b was further laminated, so that the etching selectivity was improved and the margin was improved. As a result, the silicon nitride film 123 formed further below is not damaged at all.
[0120]
Here, since the (110) plane silicon wafer is used for the base substrate 121, the (111) plane vertical wall is formed by anisotropic etching with potassium hydroxide. Since the vertical wall is obtained by using the (110) plane wafer, the discharge chambers can be arranged with high density. Although an aqueous potassium hydroxide solution is used here, an alkaline solution such as TMAH (tetramethylammonium hydroxide solution), EDP (ethylenediamine pyrocatechol), lithium hydroxide, or the like can also be used.
[0121]
Thereafter, as shown in FIG. 4D, the silicon nitride film 126 is removed by hot phosphoric acid. In this way, the laminated diaphragm 130 of the silicon nitride film 122a having a thickness of 50 nm, the silicon oxide film 122b having a thickness of 50 nm, the silicon nitride film 123 having a tensile stress of 150 nm, the silicon oxide film 124 having a thickness of 150 nm, and the discharge chamber 6 Is completed.
[0122]
Next, an inkjet head according to a thirteenth embodiment will be described with reference to FIG. In addition, the figure is a cross-sectional explanatory drawing along the diaphragm lateral direction of the head.
In this embodiment, an insulating film 26 is formed on the surface of the electrode 14 in the ink jet head of the third embodiment. That is, as described above, in order to reduce the driving voltage, the interval between the electrodes 14 must be reduced. However, when the electrodes 14 are formed at such a minute interval, even if the dust is small, the electrodes 14 may cause a short circuit and may cause a malfunction. Also, since the distance is very small, even when a minute water droplet is generated on the surface of the electrode 14 due to air humidity, it may cause a short circuit. .
[0123]
Therefore, by providing the insulating film 26 on the surface of the electrode 14, it is possible to reduce malfunction due to a short circuit between the electrodes 14. In addition, an operation failure may occur due to the discharge between the electrodes 14 when a voltage is applied. By providing the insulating film 26 against this, the breakdown voltage can be improved and the droplet discharge with high reliability. A head is obtained.
[0124]
Here, a thermal oxide film can be used as the insulating film 26. That is, when single crystal silicon or polysilicon is used for the electrode 14, the thermal oxide film can be uniformly and accurately formed on the electrode surface. Further, the thermal oxide film has high mechanical and electrical reliability, and a highly reliable droplet discharge head can be realized.
[0125]
In this case, the thermal oxide film grows while consuming about 44% of silicon. Referring to FIG. 30, the electrode 14 before oxidation is in a state indicated by a dotted line A, and is provided with a gap G1 therebetween. If a thermal oxide film (insulating film 26) having a thickness t is formed on this, silicon having a thickness of about 0.44t is consumed, and the distance between the electrodes 14 is G3 and the space distance is G2.
[0126]
The effective gap G, which is the electrical inter-electrode spacing before forming the thermal oxide film, is G = G1, and the effective gap G ′ when the thermal oxide film of thickness t is formed is the dielectric constant of the thermal oxide film. Is expressed by the following equation (2).
[0127]
[Expression 2]

[0128]
Here, since the dielectric constant ε of the thermal oxide film is 3.7 to 3.9, G ′ <G, and the effective gap can be reduced by forming the thermal oxide film. As described above, the force acting between the electrodes 14 and 14 can be increased as the effective gap is smaller, and the electrostatic force acting between the electrodes 14 and 14 is inversely proportional to the square of the effective gap. Therefore, the force can be increased or the driving voltage can be lowered by forming the thermal oxide film and reducing the execution gap. There is a limit to processing the electrodes to form a narrow interval, and when grooves are formed by dry etching, the limit is about 0.5 μm. By forming an insulating film on the electrode surface, an effective gap smaller than this limit value can be formed, and the drive voltage can be lowered.
[0129]
Specifically, the dielectric constant of the thermal oxide film used here was 3.8. When G1 is 0.5 μm and the insulating film thickness t is 0.4 μm, the effective gap G ′ is 0.26 μm, and the effective gap can be reduced to about ½. From the above-described equation (1), when converted to the electrostatic force acting between the electrodes, it becomes 3.7 times, and when trying to obtain the same electrostatic force, the voltage can be reduced to about ½.
[0130]
That is, when G1 = 0.55 μm (ε = 3.8)
When t = 0.2 μm: G2 = 0.28 μm, G ′ = 0.38 μm
When t = 0.4 μm: G2 = 0.06 μm, G ′ = 0.26 μm
It becomes.
[0131]
As a film grown by consuming silicon, there is a thermal nitride film in addition to the thermal oxide film, and this thermal nitride film is also mechanically and electrically reliable and can be used as an insulating film.
[0132]
In addition, a deposited insulating film can be used as the insulating film 26. The deposited insulating film deposits a film without consuming silicon. For example, high temperature thermal CVD, silicon oxide film by low temperature thermal CVD, silicon oxide film or silicon nitride film by PE-CVD, silicon nitride film by LP-CVD, silicon oxide film by sputtering, titanium oxide, molybdenum oxide, tungsten oxide, etc. Examples thereof include a metal oxide film or a film obtained by oxidizing a metal film by vacuum deposition. Film formation by CVD is preferable in that a film can be uniformly formed on the surface of the structure.
[0133]
As an example of the deposited insulating film, a silicon oxide film is formed by high-temperature CVD. Since the silicon oxide film formed by high-temperature CVD is deposited on the surface to be formed, the electrode surface before film formation and the electrode surface after film formation do not change. Therefore, when the film is formed by the thickness t, the electrode interval G1 before and after the film formation does not change, and the space interval becomes G2 which is narrowed by the film thickness.
[0134]
Here, the effective gap G, which is the electrical inter-electrode spacing before forming the deposited insulating film (insulating film 26), is G = G1. The effective gap G 'when the deposited insulating film having the thickness t is formed is expressed by the following equation (3), where ε1 is the dielectric constant of the oxide film.
[0135]
[Equation 3]

[0136]
Since the dielectric constant ε1 of the silicon oxide film by high-temperature CVD is 4.0 to 4.5, G ′ <G, and the effective gap can be reduced by forming the oxide film (deposited insulating film). . In addition, since the film can be formed without consuming the electrode material as in the case of the thermal oxide film, the effective gap can be further reduced, and the voltage can be further reduced. The dielectric constant of the oxide film used here was 4.0. When G1 is 0.5 μm and t is 0.2 μm, G ′ becomes 0.2 μm and the effective gap can be reduced to 2/5. When the electrostatic force acting between the electrodes is converted from the above-described equation (1), it becomes six times, and when trying to obtain the same electrostatic force, the voltage can be reduced to 2/5.
[0137]
That is, when G1 = 0.5 μm (ε = 4.0)
When t = 0.2 μm: G2 = 0.1 μm, G ′ = 0.2 μm
It becomes.
[0138]
The higher the dielectric constant, the greater the effect of reducing the effective gap. In addition, the effect of reducing the effective gap becomes larger by using a film having a larger dielectric constant such as a silicon oxide film of PE-CVD.
[0139]
Furthermore, a conductive film can be formed on the surface of the electrode 14. By forming a conductive film on the electrode surface, the electrode interval was G1 before film formation, whereas the electrode interval after film formation of thickness t is G2 which is smaller by twice the film formation thickness. Become. Thereby, the electrode interval can be reduced by forming the conductive film, and the electrostatic force can be improved and the drive voltage can be lowered. Further, in combination with the method of forming an insulating film on the electrode surface, it is possible to improve the reliability and further reduce the voltage.
[0140]
As the conductive film to be formed, polysilicon or a metal film such as aluminum, nickel, tungsten gold or the like by sputtering or vacuum deposition can be used. However, polysilicon that can be uniformly formed on the electrode surface which is a structure is the most preferable. preferable. In this case, it is preferable to introduce impurity atoms having n-type or p-type conductivity into the polysilicon, for example, phosphorus or arsenic for n-type, boron or antimony for p-type.
[0141]
Next, an inkjet head according to a fourteenth embodiment will be described with reference to FIG. In addition, the figure is a cross-sectional explanatory drawing along the diaphragm lateral direction of the head.
In this embodiment, an electrode (this is referred to as a fixed electrode) 154 is provided on the wall surface portion of the recess 16 of the second substrate 2, and a plurality of electrodes are formed from the fixed electrode 154 on the short-side end side of the diaphragm 10. (This is referred to as a movable electrode.) 155 are provided at predetermined intervals. Other configurations are the same as those of the third embodiment.
[0142]
The operation of the ink jet head configured as described above will be described. When a pulse potential of 0 V to 40 V is applied to the fixed electrode 154 and every other movable electrode 155 by the drive circuit, the surfaces of the fixed electrode 154 and every other movable electrode 155 are positively charged, and the pulse potential is applied. As shown in FIG. 32, the electrostatic attraction action works between the adjacent movable electrodes 155, and the diaphragm 10 bends downward. As a result, the internal volume of the discharge chamber 6 increases, so that ink is supplied from the common liquid chamber 8 into the discharge chamber 6 through the fluid resistance portion 7.
[0143]
When the potentials of the electrodes 154 and 155 return to 0 V, there is no potential difference between the electrodes 154 and 155 and 155 and 155, and the diaphragm 10 is restored to the original state. When the vibration plate 10 is restored, the pressure in the discharge chamber 6 rapidly increases, and ink droplets are discharged from the nozzle holes 4. That is, in this embodiment, ink droplets can be ejected by a pulling method.
[0144]
Next, an inkjet head according to a fifteenth embodiment will be described with reference to FIG. In addition, the figure is a cross-sectional explanatory drawing along the diaphragm lateral direction of the head.
In this embodiment, the third embodiment and the fourteenth embodiment are combined, a fixed electrode 154 is provided on the wall surface portion of the recess 16 of the second substrate 2, and a plurality of movable members are fixed to the diaphragm 10 from the fixed electrode 154. Electrodes 155 are provided at predetermined intervals.
[0145]
The operation of the ink jet head configured as described above will be described. The drive circuit is connected to every other movable electrode 155 of the group of movable electrodes 155 (end portion side movable electrode group) on the fixed electrode 154 and the diaphragm lateral end side. When a pulse potential of 0 V to 40 V is applied by the above, the surfaces of the fixed electrode 154 and every other movable electrode 155 of the end side movable electrode group are positively charged, and adjacent movable electrodes 155 to which no pulse potential is applied. In the same manner as in FIG. 32, electrostatic attraction acts and the diaphragm 10 bends downward. As a result, the internal volume of the discharge chamber 6 increases, so that ink is supplied from the common liquid chamber 8 into the discharge chamber 6 through the fluid resistance portion 7.
[0146]
Therefore, the voltage application to the fixed electrode 155 was canceled, and the voltage was applied by applying a pulse potential of 0V to 40V to every other movable electrode 155 including the movable electrode 155 at the center. The surface of the movable electrode 155 is positively charged, and the electrostatic attraction action works between the adjacent electrodes 155 to which no pulse potential is applied, as shown in FIG. 5, and the diaphragm 10 moves upward. Deflection. As a result, the pressure in the discharge chamber 6 rapidly increases and ink droplets are discharged from the nozzle holes 4. That is, in this embodiment, ink droplets can be ejected by a pull-push method.
[0147]
Next, an inkjet head according to a sixteenth embodiment will be described with reference to FIG. In addition, the figure is a cross-sectional explanatory drawing along the diaphragm lateral direction of the head.
In this embodiment, the plurality of electrodes 14 are provided on the discharge chamber 6 side using the diaphragm 10 of the third embodiment. In this case, in order to prevent the electrode 14 from being corroded by ink, an insulating film 157 such as a nitride film is formed on the surface of the electrode 14 as a liquid resistant film (here, an ink resistant film).
[0148]
In such a configuration, by applying a pulse potential to every other electrode 14, the diaphragm 10 is deformed to the opposite side to the discharge chamber 6, and ink is supplied into the discharge chamber 6. When the application of the pulse potential to the plurality of electrodes 14 is stopped from the state, the diaphragm 10 is restored and ink droplets are ejected. That is, in this case, ink droplets can be ejected in the same manner as the strike method.
[0149]
Next, an inkjet head according to a seventeenth embodiment will be described with reference to FIG. In addition, the figure is a cross-sectional explanatory drawing along the diaphragm lateral direction of the head.
In this embodiment, using the diaphragm 50 of the sixth embodiment, the plurality of electrodes 155 are provided on the surface opposite to the discharge chamber 6 at the center in the short side direction of the diaphragm 50, and the diaphragm 50 is short. The plurality of electrodes 155 are provided on the discharge chamber 6 side at both ends in the hand direction, and the fixed electrode 154 is disposed so as to face the electrode 155 at the endmost portion on the discharge chamber 6 side. In order to prevent the electrodes 154 and 155 from being corroded by ink, an insulating film 157 such as a nitride film is formed on the surfaces of the electrodes 154 and 155 as a liquid-resistant film (here, an ink-resistant film). ing.
[0150]
Since it comprised in this way, while applying every other pulse-like electric potential with respect to the electrode 155 of the both ends of the fixed electrode 154 and the diaphragm 50, an electrostatic force is generated, and the center part side of the diaphragm 50 is provided. When every other pulsed potential is applied to the electrode 155 to generate an electrostatic force, the diaphragm 50 is deformed to the discharge chamber 6 side by the displacement of the upper and lower electrodes 155. In this case, the diaphragm 50 undergoes different deformations at both end portions and the central portion thereof, so that the deformation shape of the vibration plate 50 can be made close to an ideal Gaussian shape, and the droplet discharge characteristics are further improved.
[0151]
Next, an ink cartridge according to the present invention will be described with reference to FIG. The ink cartridge 200 is obtained by integrating the ink jet head 201 according to any of the above embodiments having the nozzle hole 201 and the like, and the ink tank 202 that supplies ink to the ink jet head 201.
[0152]
As described above, in the case of an ink tank integrated head, the cost reduction and reliability of the head immediately leads to the cost reduction and reliability of the entire ink cartridge. By reducing manufacturing defects, the yield and reliability of the ink cartridge can be improved, and the cost of the head-integrated ink cartridge can be reduced.
[0153]
  Equipped with an inkjet head or ink cartridge according to the present inventionAs an image forming apparatus including an apparatus for discharging droplets according to the present inventionAn example of the ink jet recording apparatus will be described with reference to FIGS. FIG. 37 is a perspective explanatory view of the recording apparatus, and FIG. 38 is a side explanatory view of a mechanism portion of the recording apparatus.
[0154]
This ink jet recording apparatus includes a carriage movable in the main scanning direction inside the recording apparatus main body 211, a recording head comprising the ink jet head according to the present invention mounted on the carriage, an ink cartridge for supplying ink to the recording head, and the like. A paper feed cassette (or a paper feed tray) 214 on which a large number of sheets 213 can be stacked from the front side is detachably attached to the lower part of the apparatus main body 211. In addition, the manual feed tray 215 for manually feeding the paper 213 can be opened, the paper 213 fed from the paper feed cassette 214 or the manual feed tray 215 is taken in, and required by the printing mechanism unit 212. After the image is recorded, it is discharged to a discharge tray 216 mounted on the rear side.
[0155]
The printing mechanism 212 holds the carriage 223 slidably in the main scanning direction (the direction perpendicular to the paper in FIG. 38) with a main guide rod 221 and a sub guide rod 222 which are guide members horizontally mounted on left and right side plates (not shown). The carriage 223 includes a head 224 that is an ink jet head that is a droplet discharge head according to the present invention that discharges ink droplets of each color of yellow (Y), cyan (C), magenta (M), and black (Bk). Are arranged in a direction crossing the main scanning direction and the ink droplet discharge direction is directed downward. Also, each ink cartridge 225 for supplying ink of each color to the head 224 is replaceably mounted on the carriage 223. Note that the head-integrated ink cartridge according to the present invention may be mounted.
[0156]
The ink cartridge 225 has an air port that communicates with the atmosphere upward, a supply port that supplies ink to the inkjet head below, and a porous body filled with ink inside, and the capillary force of the porous body. Thus, the ink supplied to the inkjet head is maintained at a slight negative pressure.
[0157]
Further, although the heads 224 of the respective colors are used here as the recording heads, a single head having nozzles for ejecting ink droplets of the respective colors may be used.
[0158]
Here, the carriage 223 is slidably fitted to the main guide rod 221 on the rear side (downstream side in the paper conveyance direction), and is slidably mounted on the secondary guide rod 222 on the front side (upstream side in the paper conveyance direction). is doing. In order to move and scan the carriage 223 in the main scanning direction, a timing belt 230 is stretched between a driving pulley 228 and a driven pulley 229 that are rotationally driven by a main scanning motor 227, and the timing belt 230 is attached to the carriage 223. The carriage 223 is reciprocally driven by forward and reverse rotation of the main scanning motor 227.
[0159]
On the other hand, in order to convey the sheet 213 set in the sheet feeding cassette 214 to the lower side of the head 224, the sheet feeding roller 231 and the friction pad 232 for separating and feeding the sheet 213 from the sheet feeding cassette 214 and the sheet 213 are guided. A guide member 233, a conveyance roller 234 that inverts and conveys the fed paper 213, a conveyance roller 235 that is pressed against the circumferential surface of the conveyance roller 234, and a leading end that defines a feeding angle of the sheet 213 from the conveyance roller 234 A roller 236 is provided. The transport roller 234 is rotationally driven by a sub-scanning motor 237 via a gear train.
[0160]
A printing receiving member 239 is provided as a paper guide member for guiding the paper 213 fed from the transport roller 234 below the recording head 224 corresponding to the range of movement of the carriage 223 in the main scanning direction. On the downstream side of the printing receiving member 239 in the sheet conveyance direction, a conveyance roller 241 and a spur 242 that are rotationally driven to send the sheet 213 in the sheet discharge direction are provided, and the sheet 213 is further discharged to the sheet discharge tray 216. A roller 243 and a spur 244, and guide members 245 and 246 that form a paper discharge path are disposed.
[0161]
At the time of recording, the recording head 224 is driven according to the image signal while moving the carriage 223, thereby ejecting ink onto the stopped sheet 213 to record one line, and after the sheet 213 is conveyed by a predetermined amount, Record the line. Upon receiving a recording end signal or a signal that the trailing edge of the sheet 213 reaches the recording area, the recording operation is terminated and the sheet 213 is discharged. In this case, since the inkjet head according to the present invention constituting the head 224 has high droplet discharge efficiency, it is possible to stably record an image with high image quality.
[0162]
A recovery device 247 for recovering defective ejection of the head 224 is disposed at a position outside the recording area on the right end side in the movement direction of the carriage 223. The recovery device 247 includes a cap unit, a suction unit, and a cleaning unit. The carriage 223 is moved to the recovery device 247 side during printing standby and the head 224 is capped by the capping means, and the ejection port portion is kept in a wet state to prevent ejection failure due to ink drying. Further, by ejecting ink that is not related to recording during recording or the like, the ink viscosity of all the ejection ports is made constant and stable ejection performance is maintained.
[0163]
When a discharge failure occurs, the discharge port (nozzle) of the head 224 is sealed with a capping unit, and bubbles and the like are sucked out together with ink from the discharge port with a suction unit through the tube. Is removed by the cleaning means to recover the ejection failure. Further, the sucked ink is discharged to a waste ink reservoir (not shown) installed at the lower part of the main body and absorbed and held by an ink absorber inside the waste ink reservoir.
[0164]
Thus, in this ink jet recording apparatus, since the ink jet head or ink cartridge embodying the present invention is mounted, there is no ink droplet ejection failure due to vibration plate drive failure, and stable ink droplet ejection characteristics are obtained, Image quality is improved. In addition, since a head that can be driven at a low voltage is mounted, the power consumption of the entire inkjet recording apparatus can be reduced.
[0165]
Next, a micro pump according to the present invention will be described with reference to FIG. In addition, the figure is principal part cross-sectional explanatory drawing of the micropump.
This micro pump has a laminated structure in which a flow path substrate 301 and a protective substrate 302 are stacked and joined. A flow path 303 through which a fluid flows is formed on the flow path substrate 301 and one wall surface of the flow path 303 is formed. A movable plate 304 (such as a deformable single layer or laminated insulating thin film, a main layer (silicon film or silicon nitride film) and a laminated film of insulating thin film as described in the embodiment of the droplet discharge head to be formed). Here, a laminated film of a silicon nitride film 304A and a silicon oxide film 304B is provided), and a portion of the movable plate 304 that is not bonded and fixed to the protective substrate 302 is a movable portion 305.
[0166]
A plurality of electrodes 307 are provided at predetermined intervals on the opposite surface of the movable portion 305 on the flow path 303 side, like the ink jet head. The protective substrate 302 has a function similar to that of the second substrate 2 of the head, and has a recess 308 for disposing the electrode 307. Here, the protective substrate 302 forms a recess 308 by providing a spacer portion 309 on a flat plate substrate.
[0167]
The operation principle of the micropump will be described. Since the electrostatic attraction force is generated between the electrodes 307 by applying a pulse potential to every other electrode 307 as described above, the movable portion 305 is formed in the flow path 303. Deforms to the side. Here, by sequentially driving the movable portion 305 from the right side in the figure, the fluid in the flow path 303 flows in the direction of the arrow, and the fluid can be transported.
[0168]
In this embodiment, an example in which a plurality of movable parts are provided is shown, but one movable part may be provided. Further, in order to increase the transportation efficiency, one or more valves such as a check valve can be provided between the movable parts.
[0169]
Next, an embodiment of an optical device according to the present invention will be described with reference to FIG. This figure is a schematic configuration diagram of the device.
In this optical device, a deformable mirror 401 and a protective substrate 402 are overlapped and bonded. The mirror 401 can be composed of a deformable single layer or laminated insulating thin film as described in the embodiment of the droplet discharge head, a laminated layer of a main layer (silicon film or silicon nitride film) and an insulating thin film, or the like. Here, a laminated film of a main layer 401A and an insulating thin film 401B is used.
[0170]
A portion of the mirror 401 that is not bonded and fixed to the protective substrate 402 is a movable portion 405. The movable portion 405 is provided with a plurality of electrodes 407 at predetermined intervals. The protective substrate 402 has a function similar to that of the second substrate 2 of the head, and has a recess 408 in which the electrode 407 is disposed. Here, the protective substrate 402 forms a recess 408 by providing a spacer portion 409 on a flat plate substrate. The surface of the mirror 301 is preferably formed with a dielectric multilayer film or a metal film in order to increase the reflectance.
[0171]
The principle of this optical device will be described. An electrostatic attraction force is generated between the electrodes 407 by applying a pulse potential to every other electrode 407 provided on the movable part 405 of the mirror 401. 405 is deformed into a convex shape to form a convex mirror. Therefore, when the light from the light source 410 is applied to the mirror 401 via the lens 411, when the mirror 401 is not driven, the light is reflected at the same angle as the incident angle, but when the mirror 401 is driven to the movable portion 405. Since the movable part 405 becomes a convex mirror, the reflected light becomes divergent light. Thereby, an optical modulation device can be realized.
[0172]
Therefore, an example in which this optical device is applied will be described with reference to FIGS. In this example, the optical devices described above are two-dimensionally arranged, and the movable part 405 of each mirror is driven independently. Although a 4 × 4 array is shown here, it is possible to arrange more than this. Further, the electrode 407 is separated in a lattice shape on the surface of the movable portion 405 (in the embodiment of the droplet discharge head, the electrode 14 can also be separated in a lattice shape in the same manner as the electrode 405). .
[0173]
Therefore, similarly to FIG. 40 described above, the light from the light source 410 is applied to the mirror 401 via the lens 411, and the light incident on the position where the mirror 401 is not driven enters the projection lens 412. On the other hand, a portion where the movable portion 405 of the mirror 401 is deformed by applying a voltage to the electrode 407 becomes a convex mirror, so that light diverges and hardly enters the projection lens 412. The light incident on the projection lens 412 is projected on a screen (not shown) or the like, and an image can be displayed on the screen.
[0174]
  In the above embodiment, the example in which the ink jet head is applied as a liquid droplet ejecting head has been described. The present invention can also be applied to other droplet discharge heads such as a droplet discharge head that discharges the sample as droplets. In addition to micropumps and optical devices (light modulation devices), microactuators can also be applied to microswitches (microrelays), multi-optical lens actuators (optical switches), microflowmeters, pressure sensors, etc. it can.Further, as described above, the present invention can also be applied to an image forming apparatus such as a printer, a facsimile machine, and a copying apparatus, and an apparatus that discharges droplets.
[0175]
【The invention's effect】
As described above, according to the droplet discharge head according to the present invention, from the both sides of the diaphragm formed of the insulating thin film or the electrically conductive structure that is electrically insulated and separated from each other on one side. Since at least two electrodes are provided and an electrostatic force is generated between the electrodes to deform the diaphragm, a head capable of high cost printing with high droplet discharge efficiency can be obtained at low cost.
[0176]
  According to the droplet discharge head according to the present invention, at least one electrode made of a conductive structure is provided on both surfaces or one surface of the diaphragm formed of an insulating thin film, and the diaphragm is fixed. Since the wall surface is provided with an electrode facing the electrode at a predetermined interval and the diaphragm is deformed by generating an electrostatic force between the electrodes, the droplet discharge efficiency is high at a low cost. A head capable of image quality printing is obtained.
[0177]
In these droplet discharge heads according to the present invention, the insulating thin film forming the vibration plate is a laminated film of insulating films, so that the stress of each film can be individually controlled, and the vibration plate is bent by internal stress. The bending deformation can be prevented, and the occurrence of pinholes can be prevented because of the laminated film.
[0178]
In addition, since the insulating thin film that forms the diaphragm has a tensile stress, it can avoid bending deformation due to the bending of the diaphragm, and the in-plane variation of electrostatic attraction generated in the electrode pair can be avoided. In addition, the effective rigidity of the diaphragm can be improved and droplets can be ejected with a thinner diaphragm.
[0179]
In this case, by using a silicon nitride film as the insulating film having a tensile stress, it can function as an etching stopper when the liquid chamber is formed of a silicon substrate, and a highly accurate diaphragm can be formed. By setting the thickness of the silicon nitride film within the range of 10 nm to 900 nm, it is possible to ensure rigidity and drive at a low voltage. Furthermore, since the silicon nitride film contains impurity atoms, stress relaxation can be easily realized while maintaining tensile stress.
[0180]
Further, by using an organic resin film as the insulating thin film that forms the diaphragm, a thicker diaphragm can be formed because there are many materials having a low Young's modulus, and pinhole defects in the diaphragm can be prevented. By using a polyimide film as the organic resin film, the corrosion resistance of the liquid is improved and a liquid having a chemical property can be discharged.
[0181]
The droplet discharge head according to the present invention electrically insulates the surface of the insulating thin film of the diaphragm formed of the laminated film of silicon and the insulating thin film provided on the surface opposite to the silicon discharge chamber. The diaphragm is deformed by providing at least two electrodes consisting of separated conductive structures and generating an electrostatic force between the electrodes, so it is possible to achieve high-quality printing at low cost with high droplet ejection efficiency. Can be obtained, and the thickness of the diaphragm can be easily controlled.
[0182]
Further, according to the droplet discharge head according to the present invention, the surface of the insulating thin film of the diaphragm formed of the laminated film of silicon and the insulating thin film provided on the surface opposite to the silicon discharge chamber is made conductive. The structure is provided with at least one electrode, and the fixed portion is provided with an electrode facing the electrode at a predetermined interval, and the diaphragm is deformed by generating an electrostatic force between the electrodes. Thus, a head with high droplet discharge efficiency and high-quality printing can be obtained, and the thickness of the diaphragm can be easily controlled.
[0183]
In each of the droplet discharge heads according to the present invention, the silicon of the diaphragm contains n-type or p-type impurity atoms that function as an etching stopper when performing anisotropic etching. Thus, a highly accurate diaphragm can be formed.
[0184]
According to the droplet discharge head according to the present invention, the conductive layers that are electrically insulated and separated from each other on one side or both sides of the diaphragm formed by the main layer and a film having selectivity for silicon etching are provided. Since the diaphragm is deformed by providing at least two electrodes composed of a structure and generating an electrostatic force between the electrodes, a head capable of high cost printing with high droplet discharge efficiency is obtained at low cost. Further, etching damage to the main layer of the diaphragm when the liquid chamber is formed by etching can be prevented, and a more accurate diaphragm can be formed.
[0185]
  Further, according to the liquid droplet ejection head according to the present invention, at least the vibration plate formed of the main layer and the film having selectivity with respect to the silicon etching, or at least one of the structures having conductivity on one surface. While providing one electrode,Wall part to fix the diaphragmSince the diaphragm is deformed by providing an electrode facing the electrode at a predetermined interval and generating an electrostatic force between the electrodes, the head is capable of high cost printing with high droplet ejection efficiency at low cost. In addition, etching damage to the main layer of the diaphragm when the liquid chamber is formed by etching can be prevented, and a more accurate diaphragm can be formed.
[0186]
Furthermore, according to the liquid droplet ejection head according to the present invention, the film having etching selectivity with respect to the silicon etching / the main layer / both surfaces of the diaphragm formed of the film having selectivity with respect to the etching of the electrode material, or The diaphragm is deformed by providing at least two electrodes made of conductive structures that are electrically insulated and separated from each other on one surface and generating an electrostatic force between the electrodes. A head having high ejection efficiency and capable of high-quality printing is obtained, and etching damage to the main layer of the diaphragm when the liquid chamber and the electrode are formed by etching can be prevented, so that a highly accurate diaphragm can be formed.
[0187]
  Furthermore, according to the droplet discharge head according to the present invention, both sides of the diaphragm formed of a film having etching selectivity with respect to silicon etching / main layer / film having selectivity with respect to etching of the electrode material, Alternatively, at least one electrode made of a conductive structure is provided on one surface,Wall part to fix the diaphragmSince the diaphragm is deformed by providing an electrode facing the electrode at a predetermined interval and generating an electrostatic force between the electrodes, the head is capable of high cost printing with high droplet ejection efficiency at low cost. In addition, etching damage to the main layer of the diaphragm when the liquid chamber and the electrode are formed by etching can be prevented, and a more accurate diaphragm can be formed.
[0188]
In each of the droplet discharge heads according to the present invention, the film having etching selectivity with respect to the silicon etching is a silicon oxide film or a laminated film of a silicon nitride film and a silicon oxide film, so that Etching damage can be prevented more reliably. Further, since the film having etching selectivity with respect to the etching of the electrode material is a silicon oxide film, etching damage to the diaphragm can be prevented more reliably. Furthermore, since the main layer has a tensile stress, it is possible to avoid bending deformation due to the bending of the diaphragm, to reduce the in-plane variation of the electrostatic attraction generated in the electrode pair, and to further improve the effective vibration of the diaphragm. The rigidity can be improved, and the droplet can be ejected with a thinner diaphragm.
[0189]
In addition, the main layer can be a silicon nitride film, so that the stress can be easily controlled while maintaining the tensile stress, or the main layer can be formed by using a deposition method or a polishing method so as to have a thickness. Controllability is improved. Furthermore, when the thickness of the diaphragm is 5 μm or less, low voltage driving can be achieved while ensuring rigidity.
[0190]
According to the ink cartridge of the present invention, since the liquid droplet ejection head according to the present invention for ejecting ink droplets and the ink tank for supplying ink to the liquid droplet ejection head are integrated, manufacturing defects are reduced and the cost is reduced. Can be realized.
[0191]
  According to the ink jet recording apparatus according to the present invention, the liquid droplet ejection head or the ink cartridge according to the present invention is used as the ink jet head that ejects ink droplets.powered byTherefore, the cost of the apparatus can be reduced.According to the image forming apparatus of the present invention, since the liquid droplet ejection head according to the present invention is provided, the cost can be reduced. According to the apparatus for ejecting droplets according to the present invention, since the droplet ejection head according to the present invention is provided, the cost can be reduced.
[0192]
According to the microactuator of the present invention, at least two electrodes made of electrically conductive structures that are electrically insulated and separated from each other are provided on both surfaces of one of the movable parts formed of an insulating thin film, or one surface, Since the movable part is deformed by generating an electrostatic force between the electrodes, an actuator with high operating efficiency can be obtained at low cost.
[0193]
  According to the microactuator according to the present invention, at least one electrode made of a conductive structure is provided on both surfaces of the movable part formed of an insulating thin film or on one surface,Wall part to fix the movable partIn this case, the movable part is deformed by providing an electrode opposed to the electrode of the movable part at a predetermined interval and generating an electrostatic force between the electrodes. Therefore, an actuator with low cost and high operating efficiency can be obtained.
[0194]
According to the micropump of the present invention, the micropump transports liquid by deformation of the movable part, and is electrically insulated and separated from each other on one side or both sides of the movable part formed of an insulating thin film. Since the movable part is deformed by providing two electrodes and generating an electrostatic force between the electrodes, the size can be reduced, the power consumption can be reduced, and the cost can be reduced.
[0195]
According to the light modulation device of the present invention, the light modulation device changes the reflection direction of light by the displacement of the mirror formed on the movable part, and is electrically applied to both or one side of the movable part formed of an insulating thin film. Since two electrodes that are insulated and separated from each other and the mirror is displaced by deforming the movable part by applying an electrostatic force between the electrodes, it is possible to reduce the size and power consumption and reduce the cost. I can plan.
[Brief description of the drawings]
FIG. 1 is an exploded perspective view of an inkjet head according to a first embodiment of a droplet discharge head of the present invention.
FIG. 2 is a cross-sectional explanatory view of the head in the longitudinal direction of the diaphragm.
FIG. 3 is an enlarged cross-sectional explanatory view of the main part of the head in the short direction of the diaphragm.
FIG. 4 is an explanatory plan view for explaining an electrode arrangement pattern of the head.
FIG. 5 is an enlarged sectional explanatory view of a main part for explaining the operation of the head.
FIG. 6 is a cross-sectional explanatory view along the longitudinal direction of the diaphragm of the inkjet head according to the second embodiment.
FIG. 7 is a cross-sectional explanatory diagram of a main part along the short side direction of the diaphragm of the head.
FIG. 8 is a cross-sectional explanatory view along the longitudinal direction of the diaphragm of the ink jet head according to the third embodiment.
FIG. 9 is a cross-sectional explanatory view of a main part along the short side direction of the diaphragm of the head.
FIG. 10 is a cross-sectional explanatory view along the longitudinal direction of the diaphragm of the ink jet head according to the fourth and fifth embodiments.
FIG. 11 is a cross-sectional explanatory diagram of a main part along the short side direction of the diaphragm of the head.
FIG. 12 is a cross-sectional explanatory view of a main part along the diaphragm lateral direction showing another example of the ink jet head according to the embodiment.
FIG. 13 is a cross-sectional explanatory view of a main part along the diaphragm lateral direction showing still another example of the ink jet head according to the embodiment.
FIG. 14 is an explanatory diagram for explaining an example of the manufacturing process of the inkjet head according to the embodiment;
FIG. 15 is an explanatory diagram for explaining a process following FIG.
FIG. 16 is an explanatory diagram for explaining the process following FIG.
FIG. 17 is a cross-sectional explanatory view along the longitudinal direction of the diaphragm of the inkjet head according to the sixth embodiment.
FIG. 18 is a cross-sectional explanatory view of a main part along the short side direction of the diaphragm of the head.
FIG. 19 is a cross-sectional explanatory view along the longitudinal direction of the diaphragm of the ink jet head according to the seventh embodiment.
FIG. 20 is a cross-sectional explanatory diagram of a main part along the short side direction of the diaphragm of the head.
FIG. 21 is a cross-sectional explanatory view along the longitudinal direction of the diaphragm of the inkjet head according to the eighth embodiment.
FIG. 22 is a cross-sectional explanatory view of a main part along the diaphragm short-side direction of the head.
FIG. 23 is a cross-sectional explanatory view along the transversal direction of the diaphragm for explaining the inkjet head according to the ninth embodiment together with the manufacturing process thereof.
FIG. 24 is an explanatory diagram for explaining the process following FIG.
FIG. 25 is a cross-sectional explanatory view along the transversal direction of the diaphragm of the inkjet head according to the tenth embodiment.
FIG. 26 is an explanatory cross-sectional view of the inkjet head according to the eleventh embodiment along the transversal direction of the diaphragm.
FIG. 27 is a cross-sectional explanatory view along the diaphragm lateral direction for explaining the inkjet head according to the twelfth embodiment together with the manufacturing process thereof.
FIG. 28 is an explanatory diagram for explaining the process following FIG.
FIG. 29 is an explanatory cross-sectional view of the inkjet head according to the thirteenth embodiment along the transversal direction of the diaphragm.
FIG. 30 is an enlarged explanatory view of an electrode portion of the head.
FIG. 31 is an explanatory cross-sectional view of the inkjet head according to the fourteenth embodiment along the short side of the diaphragm.
FIG. 32 is an explanatory diagram for explaining the operation of the head.
FIG. 33 is an enlarged cross-sectional explanatory view of a main part along the diaphragm lateral direction of the inkjet head according to the fifteenth embodiment.
FIG. 34 is an enlarged cross-sectional explanatory view of a main part along the diaphragm lateral direction of the inkjet head according to the sixteenth embodiment.
FIG. 35 is an enlarged cross-sectional explanatory view of a main part along the diaphragm lateral direction of the inkjet head according to the seventeenth embodiment.
FIG. 36 is an explanatory perspective view for explaining the ink cartridge according to the present invention.
FIG. 37 is an explanatory perspective view illustrating an example of an ink jet recording apparatus according to the present invention.
FIG. 38 is an explanatory diagram of a mechanism unit of the recording apparatus.
FIG. 39 is a cross-sectional explanatory view illustrating an embodiment of a micropump according to the present invention.
FIG. 40 is a cross-sectional explanatory view illustrating an embodiment of an optical device according to the present invention.
41 is an explanatory perspective view illustrating an example of a light modulation device using the optical device. FIG.
FIG. 42 is a perspective view of relevant parts of the optical modulation device.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... 1st board | substrate, 2 ... 2nd board | substrate, 3 ... Nozzle plate, 4 ... Nozzle hole, 6 ... Discharge chamber, 7 ... Fluid resistance part, 8 ... Common liquid chamber 10, 20, 50, 60, 70, 90 , 100, 110 ... diaphragm, 14 ... electrode, 154 ... fixed electrode, 155 ... movable electrode, 200 ... ink cartridge, 301 ... channel substrate, 303 ... channel, 305 ... movable part, 307 ... electrode, 401 ... mirror 405: movable part, 407 ... electrode.

Claims (29)

  A single or a plurality of nozzle holes for discharging liquid droplets, a discharge chamber communicating with each of the nozzle holes, and a vibration plate constituting at least one wall of the discharge chamber, and deforming the vibration plate In the droplet discharge head that discharges droplets by applying pressure to the liquid, the diaphragm is an insulating thin film, and both sides of the diaphragm or one surface are electrically insulated and separated from each other. A droplet discharge head, comprising: at least two electrodes formed of a structure having a structure, and deforming the diaphragm by generating an electrostatic force between the electrodes. A single or a plurality of nozzle holes for discharging liquid droplets, a discharge chamber communicating with each of the nozzle holes, and a vibration plate constituting at least one wall of the discharge chamber, and deforming the vibration plate In the droplet discharge head that discharges droplets by applying pressure to the liquid, the vibration plate is an insulating thin film, and at least one of the vibration plate and a structure having conductivity on one or both surfaces thereof. An electrode is provided, an electrode facing the electrode at a predetermined interval is provided on a wall surface portion that fixes the diaphragm, and the diaphragm is deformed by generating an electrostatic force between the electrodes. Droplet discharge head.   3. The droplet discharge head according to claim 1, wherein the insulating thin film forming the vibration plate is a laminated film of insulating films.   4. The liquid droplet ejection head according to claim 1, wherein the insulating film constituting the insulating thin film forming the diaphragm has a tensile stress.   5. The droplet discharge head according to claim 4, wherein the insulating film having tensile stress is a silicon nitride film.   6. The droplet discharge head according to claim 5, wherein the silicon nitride film has a thickness in a range of 10 nm to 900 nm.   7. The droplet discharge head according to claim 5, wherein the silicon nitride film contains impurity atoms.   4. The droplet discharge head according to claim 1, wherein the insulating thin film forming the diaphragm is an organic resin film. 9. The droplet discharge head according to claim 8 , wherein the organic resin film is a polyimide film.   A single or a plurality of nozzle holes for discharging liquid droplets, a discharge chamber communicating with each of the nozzle holes, and a vibration plate constituting at least one wall of the discharge chamber, and deforming the vibration plate In the liquid droplet ejection head for ejecting liquid droplets by applying pressure to the liquid, the vibration plate is a laminated film of silicon and an insulating thin film provided on the surface opposite to the silicon discharge chamber. It is characterized in that at least two electrodes composed of conductive structures which are electrically insulated and separated from each other are provided on the surface of the insulating thin film, and the diaphragm is deformed by generating an electrostatic force between the electrodes. Droplet discharge head. A single or a plurality of nozzle holes for discharging liquid droplets, a discharge chamber communicating with each of the nozzle holes, and a vibration plate constituting at least one wall of the discharge chamber, and deforming the vibration plate In the droplet discharge head that discharges droplets by applying pressure to the liquid, the vibration plate is a laminated film of silicon and an insulating thin film provided on the surface opposite to the discharge chamber of the silicon. At least one electrode made of a conductive structure is provided on the surface of the insulating thin film, and an electrode facing the electrode at a predetermined interval is provided on a wall surface portion for fixing the diaphragm , and the electrode is interposed between the electrodes. A droplet discharge head, wherein the diaphragm is deformed by generating an electrostatic force.   12. The droplet discharge head according to claim 10, wherein the silicon of the vibration plate includes impurity atoms having a conductivity type of n-type or p-type.   A single or a plurality of nozzle holes for discharging liquid droplets, a discharge chamber communicating with each of the nozzle holes, and a vibration plate constituting at least one wall of the discharge chamber, and deforming the vibration plate In the liquid droplet ejection head for ejecting liquid droplets by applying pressure to the liquid, the diaphragm is composed of a main layer and a film having selectivity for silicon etching, and is formed on both surfaces or one surface of the diaphragm. A droplet discharge head comprising: at least two electrodes made of a conductive structure that is electrically insulated and separated from each other, and deforming the diaphragm by generating an electrostatic force between the electrodes. A single or a plurality of nozzle holes for discharging liquid droplets, a discharge chamber communicating with each of the nozzle holes, and a vibration plate constituting at least one wall of the discharge chamber, and deforming the vibration plate In the liquid droplet ejection head for ejecting liquid droplets by applying pressure to the liquid, the diaphragm is composed of a main layer and a film having selectivity with respect to silicon etching, and is formed on both surfaces or one surface of the diaphragm. Providing at least one electrode made of a conductive structure, and providing an electrode facing the electrode at a predetermined interval on a wall portion for fixing the diaphragm , and generating an electrostatic force between the electrodes A liquid droplet ejection head, wherein the vibration plate is deformed by:   A single or a plurality of nozzle holes for discharging liquid droplets, a discharge chamber communicating with each of the nozzle holes, and a vibration plate constituting at least one wall of the discharge chamber, and deforming the vibration plate In the liquid droplet ejection head for ejecting liquid droplets by applying pressure to the liquid, the diaphragm is composed of a film having etching selectivity for silicon etching / a main layer / a film having selectivity for etching of the electrode material. The vibration plate is provided with at least two electrodes made of electrically conductive structures that are electrically insulated and separated from each other on both surfaces or one surface of the diaphragm, and generating an electrostatic force between the electrodes. A droplet discharge head characterized by deforming a plate. A single or a plurality of nozzle holes for discharging liquid droplets, a discharge chamber communicating with each of the nozzle holes, and a vibration plate constituting at least one wall of the discharge chamber, and deforming the vibration plate In the liquid droplet ejection head for ejecting liquid droplets by applying pressure to the liquid, the diaphragm includes a film having etching selectivity for silicon etching / a main layer / a film having selectivity for etching the electrode material. And at least one electrode made of a conductive structure is provided on both surfaces or one surface of the diaphragm , and is opposed to the electrode at a predetermined interval on a wall surface portion to which the diaphragm is fixed. A liquid droplet ejection head, wherein electrodes are provided and the diaphragm is deformed by generating an electrostatic force between the electrodes.   17. The droplet discharge head according to claim 13, wherein the film having etching selectivity with respect to silicon etching is a silicon oxide film or a laminated film of a silicon nitride film and a silicon oxide film. Droplet discharge head.   17. The droplet discharge head according to claim 15, wherein the film having etching selectivity with respect to the etching of the electrode material is a silicon oxide film.   19. The droplet discharge head according to claim 13, wherein the main layer has a tensile stress.   20. The droplet discharge head according to claim 13, wherein the main layer is a silicon nitride film or silicon.   21. The droplet discharge head according to claim 13, wherein the vibration plate has a thickness of 5 [mu] m or less.   The droplet discharge head according to any one of claims 1 to 21, wherein the droplet discharge head is an ink cartridge in which a droplet discharge head that discharges ink droplets and an ink tank that supplies ink to the droplet discharge head are integrated. An ink cartridge which is a head.   An inkjet recording apparatus equipped with an inkjet head that ejects ink droplets, wherein the inkjet head is the droplet ejection head according to any one of claims 1 to 21 or the ink cartridge according to claim 22. Inkjet recording device.   A microactuator for deforming a movable part, wherein the movable part is made of an insulating thin film, and is made of a conductive structure that is electrically insulated from and separated from both surfaces of the movable part or one of the surfaces. A microactuator characterized in that at least two electrodes are provided, and the movable part is deformed by generating an electrostatic force between the electrodes. A micro-actuator for deforming the movable part, the movable part is made of an insulating thin film, both surfaces of the moving part, or provided with at least one electrode made of structures having conductivity on one side, the A microactuator characterized in that an electrode facing the electrode of the movable part at a predetermined interval is provided on a wall surface portion for fixing the movable part, and the movable part is deformed by generating an electrostatic force between the electrodes. .   A micropump for transporting liquid by deformation of a movable part, wherein the movable part is made of an insulating thin film, and two electrodes which are electrically isolated from each other are provided on both surfaces or one surface of the movable part. A micropump characterized by deforming the movable part by generating an electrostatic force between the electrodes.   An optical device that changes the reflection direction of light by displacement of a mirror formed on a movable part, wherein the movable part is made of an insulating thin film and is electrically insulated and separated from each other on both sides or one side of the movable part. An optical device comprising two electrodes and deforming the movable portion by generating an electrostatic force between the electrodes.   An image forming apparatus comprising a droplet discharge head to form an image, wherein the droplet discharge head is the droplet discharge head according to any one of claims 1 to 21.   An apparatus for discharging droplets from a droplet discharge head, wherein the droplet discharge head is the droplet discharge head according to any one of claims 1 to 21.

Images