JP4526676B2

JP4526676B2 - Optical deflection element and manufacturing method thereof

Info

Publication number: JP4526676B2
Application number: JP2000306378A
Authority: JP
Inventors: 和雄大高
Original assignee: Nippon Signal Co Ltd; Citizen Finetech Miyota Co Ltd
Current assignee: Nippon Signal Co Ltd; Citizen Finetech Miyota Co Ltd
Priority date: 2000-10-05
Filing date: 2000-10-05
Publication date: 2010-08-18
Anticipated expiration: 2020-10-05
Also published as: JP2002116402A

Description

【０００１】
【発明の属する技術分野】
本発明は二次元の光偏向素子に関するものである。
【０００２】
【従来の技術】
一つの素子で二次元の偏向走査をできるガルバノミラーが開発されている。ガルバノミラーをばねで支持するものであり、一つの基板にエッチング加工によりばねと可動板を形成するものであり、特開昭６０−１０７０１７号公報やＷＯ９６／３９６４３（国際公開番号）で開示されている。
【０００３】
図１は本発明に関する光偏向素子の原理構造である。以下原理説明は特開昭６０−１０７０１７号公報を引用する。シリコン単結晶からなる基板１をエッチングによりジンバルバネ状に加工する。ジンバルバネはＸ方向軸５及びＹ方向軸６を中心軸として、それぞれ独立に回転振動する。ジンバルバネ２で支持された基板１の中央の可動部面上には金属蒸着やメッキ等によりガルバノミラー３と導電コイル４が形成されている。導電コイル４に一定電流を与え、Ｘ方向の磁界７及びＹ方向の磁界８をそれぞれ独立に変化させれば、素子は電磁力によって軸５及び６を中心軸としてそれぞれ独立に回転振動する。従って、素子に形成したガルバノミラー３に一定方向から光ビームを入射しておけば、ミラー３からの反射光を被検出量に応じて二次元に偏向できる。即ち、Ｘ、Ｙの２変数を持つ信号量Ｆ（Ｘ、Ｙ）の変化を一つの素子で検出し、その出力に応じた光の偏向走査ができる。
【０００４】
図２は前記原理構造を具現化した一例である。同図において、１は｛１００｝面方位をもつｎ形シリコンの単結晶基板である。基板１は通常のＩＣ技術の一つである写真食刻法及び化学的食刻法により、支点１２−１２’及び１３−１３’をもつジンバルバネ構造を形成すべく加工される。かかる食刻加工としては、例えば、ガルバノミラー３等の形成される面を耐食性樹脂等の塗布によって保護し、その裏面をＳｉＯ_２膜又は感光性耐食性樹脂等を用いた写真食刻法等のパターニング処理を施した後、ＫＯＨ等のアルカリ溶液による異方性エッチングを行なう方法を用いる。この加工方法により、ガルバノ素子は固定部（基板１）と可動部１’に分離される。本構造は基板１とジンバルバネの厚さが異なる構造である。
【０００５】
可動部１’の大きさはガルバノ素子の可動性能に影響を及ぼす。即ち、可動部１’のダンピング効果を大きくする場合は、可動部１’の表面積を大きくして空気抵抗を大きくすればよい。一方、高速偏向走査を行なわせる場合は、可動部１’の質量を小さくする必要がある。従って、かかるガルバノ素子の用途に応じた設計、例えば、精密計器を指向する場合は、平衡型としてダンピング効果を重視し、ディスプレイ等を指向する場合は慣性駆動型として高速走査を重視する等の配慮が肝要である。かかる可動部の動作速度はガルバノ素子の配置される周囲の雰囲気によっても影響を受ける。例えば、可動部は真空中におかれれば、極めて高速に動作し、ある特定粘度の流体中におかれることにより、良好なダンピング特性を示す。従って、動作速度の精密な制御を要する場合に、ガルバノ素子周囲の流体の種類及び圧力を最適に調整する必要がある。
【０００６】
ガルバノミラー３は、例えば、Ａｇ、Ａｌ、Ａｕ等の蒸着等通常のミラーコーティング技術、または、基板１をそのままミラーポリッシュする方法等により形成される。かかるミラー形成にあたっては、特に金属蒸着法を用いる場合、熱応力によるゆがみが生じないように、例えば、基板１との熱膨張係数差の小さい材料を選択する。蒸着薄膜の厚さを最適設計する等に留意する必要がある。また、基板１をミラーポリッシュする場合は、機械歪が残らないように留意する必要がある。ガルバノミラー３自体を干渉フィルタとすれば、任意色の光を反射光として得られるため、例えば、平面ディスプレイ等に応用する場合は、カラー化が容易となる。
【０００７】
ガルバノミラー３の周囲にはこのような二次元ガルバノ素子の駆動に寄与する導電コイル４が形成される。ガルバノ素子の駆動はジンバルバネのトルクに依存し、トルクは導電コイル４の断面積に比例する。従って、導電コイル４はミラー３の外側に形成することにより、被検出量（入力）に対するジンバルバネのトルクを大きくでき高感度（偏向角／被検出力が大きい）な二次元ガルバノ素子を具現化しうる。感度をさらに向上させるためには可動部１’の面積を大きくするか、又は導電コイル４に印加する電流値を大きくする必要がある。前者の方法はジンバルバネの応答性の点で制約があり、後者の方法では導電コイル４の発熱等により制約を受ける。この条件を考慮して用途に応じた最適設計が必要である。
【０００８】
導電コイル４はＡｇ、Ａｌ、Ａｕ等の蒸着によりガルバノミラー３と同時で、且つ、同様の方法で形成されるのが望ましい。プロセスが簡略化され、歩留向上、コスト低減が図れるからである。しかし、導電コイル４は発熱を抑える観点から、抵抗を１０Ω〜１００Ωと小さくする方が良いため、蒸着膜は厚い方が良い。一方、ガルバノミラー３は前述のとおり基板１との熱膨張差による歪を抑えるために、蒸着膜は薄い方が良い。かかる状況を考慮して用途に応じた最適手法をとる必要がある。また、導電コイル４は基板１の可動部１’表面上に通常のＩＣ技術の一つである写真食刻法でパターンを形成される。この際、基板１と導電コイル４とは電気的に絶縁される必要があり、通常は図示のようにＳｉＯ２等の絶縁性膜１０を形成する。係る絶縁性膜１０もガルバノミラー３のゆがみを抑えるために、熱膨張係数、厚さ等を十分考慮する必要がある。
【０００９】
同図において、９は電極パッドであり、基板（固定部）１上に形成される。電極パッド９は、例えば、Ａｌ線等を用いたワイヤボンディング技術により外部端子と接続され、電極パッド９を通して導電コイル４に電流が印加される。電極パッド９は導電コイル４と同一の材料で同時に、例えば、蒸着等により形成されるのが望ましいが必ずしも同一又は同時にということに限定されない。
【００１０】
電極パッド９の一方は導電コイル４の最外殻端部１４と直接金属等の導体を介して接続される。なお、両者を同一材料で同時に形成する場合は、あらかじめ、写真食刻法で両者を連結したパターニングを施せばよい。また、電極パッド９の他方は導電コイル４の最内殻１５と接続される。この接続は必ず導電コイル４と交差するため、この交差部分を電気的に絶縁する必要がある。本例では図示のように、基板１の可動部１’表面上に導電コイル４の最内殻端部１５と電極パッドの端部９’とを電気的に接続する導体層１１を選択的に（この部分のみ）形成し、交差する導電コイル４との絶縁を前述したＳｉＯ_２等の絶縁性膜で行なう。その他の方法には、例えば、交差する導電コイル４をまたぐように、Ａｌ等のワイヤボンディング結線してもよい。導体層１１は基板１と逆の極性をもつ不純物（例えばボロン等）を選択的に拡散することにより形成される。
【００１１】
図３、図４、図５は従来技術による二次元光偏向素子の導電コイルパターン形成を説明するための図であり、平面図と断面図または平面図である。導電コイルパターンは基板にジンバル加工する前に形成されるが、説明の都合上ジンバル加工した基板に導電コイルパターンを形成することにする。本例では導電コイルの巻数を多くするために導電コイルを２層に形成する。
【００１２】
単結晶シリコンの基板２１の表面にスパッタリング、蒸着等により金属薄膜（好ましくはアルミニウム）を形成する。金属薄膜上面にレジストを塗布し、第１層の導電コイルパターンを形成したマスクを重ねて露光する。レジストの開口部となる部分を除去し、金属薄膜をエッチングする。レジストを除去することにより、図３の第１層導電コイルパターンが形成できる。
【００１３】
第１可動部２２には第１可動部第１層導電コイル２４が形成され、第２可動部２３には第２可動部第１層導電コイル２７が形成される。第１可動部第１層導電コイル内端部２４ａは第１可動部の中央部に形成され、第１可動部第２層導電コイル内端部２９ａ（図４）が直接積層される。第１可動部第１層導電コイル外端部２４ｂは第２可動部の内端でジンバルバネ付近に形成されている。２５は第１可動部第１層導電コイル補助電極である。２６は接続用電極で第２可動部の内端でジンバルバネ付近に形成され、第２可動部第２層導電コイル外端部２９ｂが直接積層される。
【００１４】
第２可動部第１層導電コイル内端部２７ａは第２可動部の内端に形成され、第２可動部第２層導電コイル内端部３２ａ（図４）が直接積層される。第２可動部第１層導電コイル外端部２７ｂは第２可動部の外端でジンバルバネ付近に形成されている。２８は第２可動部第２層導電コイル外端部３２ｂ（図４）への接続用電極で第２可動部の内端でジンバルバネ付近に形成され、第２可動部第２層導電コイル外端部３２ｂが直接積層される。
【００１５】
次に表面に絶縁層（例えば感光性ポリイミドまたはＳｉＯ_２）を形成し、第１層導電コイルと第２層導電コイルが直接積層される部分を除去する。その上に金属薄膜を形成する。金属薄膜上面にレジストを塗布し、第２層の導電コイルパターンを形成したマスクを重ねて露光する。レジストの開口部となる部分を除去し、金属薄膜をエッチングする。レジストを除去することにより、図４の第２層の導電コイルパターンが形成できる。
【００１６】
第１可動部２２には第１可動部第２層導電コイル２９が形成され、第２可動部２３には第２可動部第２層導電コイル３２が形成される。第１可動部第２層導電コイル内端部２９ａは第１可動部の中央部に形成され、第１可動部第１層導電コイル内端部２４ａに直接積層される。第１可動部第２層導電コイル外端部２９ｂは第２可動部の内端でジンバルバネ付近に形成される。３０は第１可動部第２層導電コイル補助電極である。３１は接続用電極で第２可動部２３の内端でジンバルバネ付近に形成され、第２可動部第１層導電コイル外端部２４ｂに直接積層される。なお、補助電極２５、３０はジンバルバネの強度を同じにするためのものである。
【００１７】
第２可動部第２層導電コイル内端部３２ａは第２可動部２３の内端に形成され、第２可動部第１層導電コイル内端部２７ａに直接積層される。第２可動部第２層導電コイル外端部３２ｂは第２可動部２３の外端でジンバルバネ付近に形成される。３３は第２可動部第１層導電コイル外端部２７ｂ接続用電極で第２可動部２３の外端でジンバルバネ付近に形成され、第２可動部第１層導電コイル外端部２７ｂに直接積層される。
【００１８】
次に表面に絶縁層を形成し、第２層コイルと接続電極パターンが直接積層される部分を除去する。その上に金属薄膜を形成する。金属薄膜上面にレジストを塗布し、接続電極パターンを形成したマスクを重ねて露光する。レジストの開口部となる部分を除去し、金属薄膜をエッチングする。レジストを除去することにより、図５の接続電極パターンが形成できる。３４、３５は第１可動部駆動用導電コイル接続電極であり、接続端子３４ａは接続用電極３１を介して第１可動部第１層導電コイル外端部２４ｂに接続される。接続端子３５ａは第１可動部第２層導電コイル外端部２９ｂに接続される。接続端子３４ｂ、３５ｂは第１可動部駆動電源に接続される。３６、３７は第２可動部駆動用導電コイル接続電極であり、接続端子３７ａは接続用電極３３を介して第２可動部第１層導電コイル外端部２７ｂに接続される。接続端子３６ａは第２可動部第２層導電コイル外端部３２ｂに接続される。接続端子３６ｂ、３７ｂは第２可動部駆動電源に接続される。
【００１９】
図６は完成したガルバノミラーの平面図（ａ）とＡ−Ａ側面断面の模式図（ｂ）である。図６（ｂ）に於いて第２可動部２３の右側では、基板２１上に第１層導電コイル２７、絶縁層３８、第２層導電コイル３２、絶縁層３８、接続電極３４が積層されている。さらにその上に保護膜（不図示）が形成される。図では大まかに表示されているが、実際にはそれぞれの膜厚は１μｍ程度である。導電コイルの幅は４０μｍ程度であり、コイル間は１０μm程度、巻数としては１５巻程度である。導電コイルに関してはガルバノミラーの振れ角や磁石の強度等により仕様が変わることは言うまでもない。
【００２０】
【発明が解決しようとする課題】
導電層（コイル、接続電極）が絶縁層を介して積層される構造であり、配線が複雑になっている。絶縁層は、感光性ポリイミドを塗布するか、ＳｉＯ_２を蒸着する等で形成している。凹凸の密集した導電コイルパターンの上へスピンナー又はスパッタリングにより絶縁薄膜を均一に形成するのは難しく、絶縁不良が発生することがある。
【００２１】
同様に、レジストを一様に塗布するのも難しくパターン幅にばらつきが発生しやすくなっている。
【００２２】
基板の片面にのみ積層した膜が形成されるため、基板に反りが発生しやすくなり、ガルバノ素子の特性が劣化している。
【００２３】
【課題を解決するための手段】
一つの基板に、枠状の固定部と、前記固定部の内側に設けられ、一対の外側ばね部によって回動可能に支持された外周側可動部と、該外周側可動部の内側に設けられ、前記外側ばね部とは軸方向が互いに直交する一対の内側ばね部によって回動可能に支持された中心側可動部と、を形成し、前記中心側可動部に反射鏡を形成し、前記各可動部上に導電コイルパターンを形成して構成される光偏向素子において、前記外周側可動部の一方の面に、外周側可動部の導電コイルパターンを形成し、前記中心側可動部は、前記外周側可動部の一方の面とは反対側の面に、中心側可動部の導電コイルパターンを形成する光偏向素子とする。
【００２４】
ばね部と二つの可動部が基板とほぼ同一の厚さの光偏向素子とする。
【００２５】
外周側可動部は、当該外周側可動部の他方の面に前記基板の反り及び歪みを抑える補助パターンを形成した光偏向素子とする。
【００２６】
一つの基板に、枠状の固定部と、前記固定部の内側に設けられ、一対の外側ばね部によって回動可能に支持された外周側可動部と、該外周側可動部の内側に設けられ、前記外側ばね部とは軸方向が互いに直交する一対の内側ばね部によって回動可能に支持された中心側可動部と、を形成し、前記中心側可動部に反射鏡を形成し、前記各可動部上に導電コイルパターンを形成する光偏向素子の製造方法において、前記外周側可動部の一方の面に、外周側可動部の導電コイルパターンを形成し、前記外周側可動部の他方の面に、前記基板の反り及び歪みを抑える補助パターンを形成し、前記中心側可動部の他方の面側の面に中心側可動部の導電コイルパターンを形成する光偏向素子の製造方法とする。
【００２７】
【発明の実施の形態】
図７から図１０により本発明の光偏向素子の製造方法を説明する。図７は表面の第１層パターン図であり平面図と断面図、図８は第２層パターン図であり平面図である。本例でもジンバル加工した基板に導電コイルパターンを形成することにする。図９は裏面の第１層パターン図であり平面図と断面図、図１０は第２層パターン図であり平面図である。
【００２８】
単結晶シリコンの基板２１の表面にスパッタリング、蒸着等により金属薄膜（好ましくはアルミニウム）を形成する。金属薄膜上面にレジストを塗布し、第１層の導電コイルパターンを形成したマスクを重ねて露光する。レジストの開口部となる部分を除去し、金属薄膜をエッチングする。レジストを除去することにより、図７の第１層導電コイルパターンを形成する。
【００２９】
第１可動部２２には第１可動部第１層導電コイル４０が形成され、第２可動部２３には第２可動部補助パターン４１、４２が形成される。第１可動部第１層導電コイル内端部４０ａは第１可動部２２の中央部に形成され、第１可動部第２層導電コイル内端部４３ａ（図８）が直接積層される。第１可動部第１層導電コイル外端部４０ｂは第２可動部２３の補助パターン４２を経て、接続電極４６と接続されている。
【００３０】
次に表面に感光性ポリイミド又はＳｉＯ_２等で絶縁層を形成し、第１層導電コイルと第２層導電コイルが直接積層される部分を除去する。その上に金属薄膜を形成する。金属薄膜上面にレジストを塗布し、第２層の導電コイルパターンを形成したマスクを重ねて露光する。レジストの開口部となる部分を除去し、金属薄膜をエッチングする。レジストを除去することにより、図８の第２層の導電コイルパターンを形成する。
【００３１】
第１可動部２２には第１可動部第２層導電コイル４３が形成され、第２可動部２３には第２可動部補助パターン４４、４５が形成される。第１可動部第２層導電コイル内端部４３ａは第１可動部２２の中央部に形成され、第１可動部第１層導電コイル内端部４０ａ（図７）に直接積層される。第１可動部第２層導電コイル外端部４３ｂは第２可動部の補助パターン４４を経て、接続電極４７と接続されている。
【００３２】
次に単結晶シリコンの基板２１の裏面にスパッタリング、蒸着等により金属薄膜（好ましくはアルミニウム）を形成する。金属薄膜上面にレジストを塗布し、第１層の導電コイルパターンを形成したマスクを重ねて露光する。レジストの開口部となる部分を除去し、金属薄膜をエッチングする。レジストを除去することにより、図９の第１層導電コイルパターンを形成する。
【００３３】
第２可動部２３には第２可動部第１層導電コイル４８を形成する。第２可動部第１層導電コイル内端部４８ａは第２可動部２３の内縁部に形成され、第２可動部第２層導電コイル内端部４９ａ（図１０）が直接積層される。他に接続用電極５０及び補助電極５１を形成するのは従来技術と同様である。第２可動部第１層導電コイル外端部は接続電極５２と接続されている。
【００３４】
次に表面に感光性ポリイミド又はＳｉＯ_２等で絶縁層を形成し、第１層導電コイルと第２層導電コイルが直接積層される部分を除去する。その上に金属薄膜を形成する。金属薄膜上面にレジストを塗布し、第２層の導電コイルパターンを形成したマスクを重ねて露光する。レジストの開口部となる部分を除去し、金属薄膜をエッチングする。レジストを除去することにより、図１０の第２層の導電コイルパターンを形成する。
【００３５】
第２可動部２３には第２可動部第２層導電コイル４９が形成され、第１可動部２２には反射鏡（ガルバノミラー）５４が形成される。第２可動部第２層導電コイル内端部４９ａは第２可動部の内縁部に形成され、第２可動部第１層導電コイル内端部４８ａ（図９）に直接積層される。第２可動部第２層導電コイル外端部は、補助電極５０と接続され、さらに接続電極５３と接続されている。５５は補助電極である。本発明のように基板の表裏に導電パターンを形成する場合、基板と可動部を支えるばね部は同一厚さか、絶縁膜やレジスト膜を形成するのに支障が無い程度の差に設計するのが好ましい。
【００３６】
図１１は前述の工程により製造した光偏向素子を裏から見た平面図と断面図である。さらに表面に保護膜を形成するか否かは適宜決定する。
【００３７】
【発明の効果】
第１可動部と第２可動部に形成する導電コイルを基板の表裏に分けたので配線が容易になり、導電コイルパターン上を横切る接続電極が不要となるのでショーと不良の発生を防止できる。
【００３８】
基板と可動部を支えるばね部は同一厚さか、絶縁膜やレジスト膜を形成するのに支障が無い程度の差にすることにより、ガルバノ素子の製造が容易になる。
【００３９】
可動部の導電コイルパターンの裏面に導電コイルパタンに対抗する補助パターンを形成したことで、基板の両面にほぼ等しい膜が形成され、可動部の反り、歪みを最小限に抑えることができる。
【図面の簡単な説明】
【図１】本発明に関する光偏向素子の原理構造
【図２】原理構造を具現化した一例
【図３】従来技術による２軸光偏向素子の導電コイルパターン形成を説明するための図であり、平面図と断面図
【図４】従来技術による２軸光偏向素子の導電コイルパターン形成を説明するための図であり、平面図
【図５】従来技術による２軸光偏向素子の導電コイルパターン形成を説明するための図であり、平面図
【図６】完成したガルバノミラーの平面図（ａ）とＡ−Ａ側面断面の模式図（ｂ）
【図７】表面の第１層パターン図であり平面図と断面図
【図８】第２層パターン図であり平面図
【図９】裏面の第１層パターン図であり平面図と断面図
【図１０】第２層パターン図であり平面図
【図１１】光偏向素子の平面図と断面図
【符号の説明】
１基板（シリコン単結晶）
１’ 可動部
２ジンバルバネ
３ガルバノミラー
４導電コイル
５Ｘ方向軸
６Ｙ方向軸
７Ｘ方向磁界
８Ｙ方向磁界
９電極パッド
９’ 電極パッドの端部
１０絶縁性膜
１１導体層
１２支点
１２’ 支点
１３支点
１３’ 支点
１４最外殻端部
１５最内殻端部
２１基板
２２第１可動部
２３第２可動部
２４第１可動部第１層導電コイル
２４ａ第１可動部第１層導電コイル内端部
２４ｂ第１可動部第１層導電コイル外端部
２５第１可動部第１層導電コイル補助電極
２６第２層接続用電極
２７第２可動部第１層導電コイル
２７ａ第２可動部第１層導電コイル内端部
２７ｂ第２可動部第１層導電コイル外端部
２８第２可動部第１層導電コイル第２層接続用電極
２９第１可動部第２層導電コイル
２９ａ第１可動部第２層導電コイル内端部
２９ｂ第１可動部第２層導電コイル外端部
３０第１可動部第２層導電コイル補助電極
３１第１層接続用電極
３２第２可動部第２層導電コイル
３２ａ第２可動部第２層導電コイル内端部
３２ｂ第２可動部第２層導電コイル外端部
３３第２可動部第２層導電コイル第２１接続用電極
３４第１可動部駆動用導電コイル接続電極
３４ａ接続端子
３４ｂ接続端子
３５第１可動部駆動用導電コイル接続電極
３５ａ接続端子
３５ｂ接続端子
３６第２可動部駆動用導電コイル接続電極
３６ａ接続端子
３６ｂ接続端子
３７第２可動部駆動用導電コイル接続電極
３７ａ接続端子
３７ｂ接続端子
３８絶縁膜
４０第１可動部第１層導電コイル
４０ａ第１可動部第１層導電コイル内端部
４０ｂ第１可動部第１層導電コイル外端部
４１第２可動部補助パターン
４２第２可動部補助パターン
４３第１可動部第２層導電コイル
４３ａ第１可動部第２層導電コイル内端部
４３ｂ第１可動部第２層導電コイル内端部
４４第２可動部補助パターン
４５第２可動部補助パターン
４６接続電極
４７接続電極
４８第２可動部第１層導電コイル
４８ａ第２可動部第１層導電コイル内端部
４９第２可動部第２層導電コイル
４９ａ第２可動部第２層導電コイル内端部
５０接続用電極
５１補助電極
５２接続電極
５３接続電極
５４反射鏡
５５補助電極[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a two-dimensional light deflection element.
[0002]
[Prior art]
Galvano mirrors that can perform two-dimensional deflection scanning with a single element have been developed. Which supports the galvanometer mirror by a spring, by etching into one board is intended to form a spring and movable plate, disclosed in JP 60-107017 JP and WO96 / 39643 (International Publication No.) Has been.
[0003]
FIG. 1 shows the principle structure of an optical deflection element according to the present invention. In the following description of the principle, reference is made to JP-A-60-1007017. The substrate 1 made of silicon single crystal is processed into a gimbal spring shape by etching. The gimbal spring oscillates independently with the X-direction axis 5 and the Y-direction axis 6 as center axes. A galvanometer mirror 3 and a conductive coil 4 are formed on the central movable part surface of the substrate 1 supported by the gimbal spring 2 by metal vapor deposition, plating, or the like. When a constant current is applied to the conductive coil 4 and the X-direction magnetic field 7 and the Y-direction magnetic field 8 are changed independently, the element rotates and vibrates independently around the axes 5 and 6 by the electromagnetic force. Therefore, if the light beam is incident on the galvanometer mirror 3 formed in the element from a certain direction, the reflected light from the mirror 3 can be deflected two-dimensionally according to the detected amount. That is, a change in the signal amount F (X, Y) having two variables of X and Y is detected by one element, and light deflection scanning according to the output can be performed.
[0004]
FIG. 2 shows an example of the principle structure. In the figure, reference numeral 1 denotes an n-type silicon single crystal substrate having a {100} plane orientation. The substrate 1 is processed to form a gimbal spring structure with fulcrums 12-12 ′ and 13-13 ′ by photolithography and chemical etching, which are one of the common IC techniques. As such etching processing, for example, the surface on which the galvanomirror 3 or the like is formed is protected by application of a corrosion resistant resin or the like, and the back surface thereof is patterned by a photolithography method using a SiO ₂ film or a photosensitive corrosion resistant resin or the like. After the treatment, a method of performing anisotropic etching with an alkaline solution such as KOH is used. By this processing method, the galvano element is separated into a fixed portion (substrate 1) and a movable portion 1 ′. This structure is a structure in which the thickness of the substrate 1 and the gimbal spring are different.
[0005]
The size of the movable part 1 ′ affects the movable performance of the galvano element. That is, in order to increase the damping effect of the movable part 1 ′, the air resistance may be increased by increasing the surface area of the movable part 1 ′. On the other hand, when high-speed deflection scanning is performed, it is necessary to reduce the mass of the movable portion 1 ′. Therefore, the design according to the use of such galvano elements, for example, when directing precision instruments, consider the damping effect as a balanced type, and when driving a display, etc., consider high-speed scanning as an inertial drive type. Is essential. The operation speed of such a movable part is also affected by the surrounding atmosphere where the galvano element is arranged. For example, when the movable part is placed in a vacuum, it operates at a very high speed and exhibits good damping characteristics by being placed in a fluid having a specific viscosity. Therefore, when precise control of the operation speed is required, it is necessary to optimally adjust the type and pressure of the fluid around the galvano element.
[0006]
The galvanometer mirror 3 is formed by, for example, a normal mirror coating technique such as vapor deposition of Ag, Al, Au or the like, or a method of mirror polishing the substrate 1 as it is. In forming such a mirror, in particular, when using a metal vapor deposition method, for example, a material having a small difference in thermal expansion coefficient from the substrate 1 is selected so as not to cause distortion due to thermal stress. It is necessary to pay attention to optimal design of the thickness of the deposited thin film. In addition, when the substrate 1 is mirror polished, care must be taken so that no mechanical strain remains. If the galvanomirror 3 itself is an interference filter, light of an arbitrary color can be obtained as reflected light. Therefore, for example, when applied to a flat display or the like, colorization becomes easy.
[0007]
Around the galvanometer mirror 3 is formed a conductive coil 4 that contributes to driving such a two-dimensional galvano element. The driving of the galvano element depends on the torque of the gimbal spring, and the torque is proportional to the cross-sectional area of the conductive coil 4. Therefore, by forming the conductive coil 4 outside the mirror 3, it is possible to increase the torque of the gimbal spring with respect to the detected amount (input) and to realize a high-sensitivity (deflection angle / large detected force) two-dimensional galvano element. . In order to further improve the sensitivity, it is necessary to increase the area of the movable portion 1 ′ or increase the value of the current applied to the conductive coil 4. The former method is limited in terms of responsiveness of the gimbal spring, and the latter method is limited by heat generation of the conductive coil 4 and the like. Considering this condition, an optimum design according to the application is required.
[0008]
The conductive coil 4 is preferably formed simultaneously with the galvanomirror 3 by vapor deposition of Ag, Al, Au or the like and in the same manner. This is because the process is simplified, yield can be improved, and cost can be reduced. However, from the viewpoint of suppressing heat generation, the conductive coil 4 is preferably made to have a resistance as small as 10Ω to 100Ω. On the other hand, the galvanometer mirror 3 is preferably thin in order to suppress distortion due to a difference in thermal expansion from the substrate 1 as described above. It is necessary to take an optimum method according to the application in consideration of such a situation. Further, the conductive coil 4 is formed with a pattern on the surface of the movable part 1 ′ of the substrate 1 by photolithography, which is one of ordinary IC techniques. At this time, the substrate 1 and the conductive coil 4 need to be electrically insulated, and usually an insulating film 10 such as SiO2 is formed as shown in the figure. In order to suppress the distortion of the galvanometer mirror 3, such an insulating film 10 needs to sufficiently consider the thermal expansion coefficient, the thickness, and the like.
[0009]
In the figure, 9 is an electrode pad, which is formed on a substrate (fixed portion) 1. The electrode pad 9 is connected to an external terminal by a wire bonding technique using, for example, an Al wire, and a current is applied to the conductive coil 4 through the electrode pad 9. The electrode pad 9 is preferably formed of the same material as that of the conductive coil 4 at the same time, for example, by vapor deposition, but is not necessarily limited to the same or the same.
[0010]
One of the electrode pads 9 is directly connected to the outermost shell end 14 of the conductive coil 4 via a conductor such as metal. In addition, when forming both simultaneously with the same material, what is necessary is just to perform the patterning which connected both by the photo-etching method beforehand. The other electrode pad 9 is connected to the innermost shell 15 of the conductive coil 4. Since this connection always crosses the conductive coil 4, it is necessary to electrically insulate this crossing portion. In this example, as shown in the drawing, a conductor layer 11 that electrically connects the innermost shell end 15 of the conductive coil 4 and the electrode pad end 9 ′ is selectively formed on the surface of the movable portion 1 ′ of the substrate 1. (Only this portion) is formed and insulated from the intersecting conductive coils 4 by the insulating film such as SiO ₂ described above. As another method, for example, a wire bonding connection of Al or the like may be performed so as to straddle the crossing conductive coils 4. The conductor layer 11 is formed by selectively diffusing impurities having a polarity opposite to that of the substrate 1 (for example, boron).
[0011]
3, 4, and 5 are views for explaining conductive coil pattern formation of a two-dimensional optical deflection element according to the prior art, and are a plan view and a cross-sectional view or a plan view. Although the conductive coil pattern is formed before the gimbal is processed on the substrate, for convenience of explanation, the conductive coil pattern is formed on the gimbaled substrate. In this example, the conductive coil is formed in two layers in order to increase the number of turns of the conductive coil.
[0012]
A metal thin film (preferably aluminum) is formed on the surface of the single crystal silicon substrate 21 by sputtering, vapor deposition or the like. A resist is applied on the upper surface of the metal thin film, and a mask on which a conductive coil pattern of the first layer is formed is overlaid and exposed. The portion that becomes the opening of the resist is removed, and the metal thin film is etched. By removing the resist, the first layer conductive coil pattern of FIG. 3 can be formed.
[0013]
A first movable part first layer conductive coil 24 is formed in the first movable part 22, and a second movable part first layer conductive coil 27 is formed in the second movable part 23. The first movable portion first layer conductive coil inner end 24a is formed at the center of the first movable portion, and the first movable portion second layer conductive coil inner end 29a (FIG. 4) is directly laminated. The first movable portion first layer conductive coil outer end 24b is formed near the gimbal spring at the inner end of the second movable portion. Reference numeral 25 denotes a first movable part first layer conductive coil auxiliary electrode. A connection electrode 26 is formed near the gimbal spring at the inner end of the second movable portion, and the second movable portion second layer conductive coil outer end portion 29b is directly laminated.
[0014]
The second movable portion first layer conductive coil inner end portion 27a is formed at the inner end of the second movable portion, and the second movable portion second layer conductive coil inner end portion 32a (FIG. 4) is directly laminated. The second movable portion first layer conductive coil outer end portion 27b is formed near the gimbal spring at the outer end of the second movable portion. Reference numeral 28 denotes an electrode for connection to the second movable portion second layer conductive coil outer end portion 32b (FIG. 4), which is formed near the gimbal spring at the inner end of the second movable portion, and the second movable portion second layer conductive coil outer end. The part 32b is directly laminated.
[0015]
Next, an insulating layer (for example, photosensitive polyimide or SiO ₂ ) is formed on the surface, and a portion where the first layer conductive coil and the second layer conductive coil are directly laminated is removed. A metal thin film is formed thereon. A resist is applied to the upper surface of the metal thin film, and a mask on which a second-layer conductive coil pattern is formed is overlaid and exposed. The portion that becomes the opening of the resist is removed, and the metal thin film is etched. By removing the resist, the conductive coil pattern of the second layer in FIG. 4 can be formed.
[0016]
A first movable part second layer conductive coil 29 is formed on the first movable part 22, and a second movable part second layer conductive coil 32 is formed on the second movable part 23. The first movable portion second layer conductive coil inner end portion 29a is formed at the center of the first movable portion, and is directly laminated on the first movable portion first layer conductive coil inner end portion 24a. The first movable portion second layer conductive coil outer end portion 29b is formed near the gimbal spring at the inner end of the second movable portion. Reference numeral 30 denotes a first movable part second layer conductive coil auxiliary electrode. Reference numeral 31 denotes a connection electrode which is formed near the gimbal spring at the inner end of the second movable portion 23 and is directly laminated on the second movable portion first layer conductive coil outer end portion 24b. The auxiliary electrodes 25 and 30 are for making the strength of the gimbal springs the same.
[0017]
The second movable portion second layer conductive coil inner end portion 32a is formed at the inner end of the second movable portion 23, and is directly laminated on the second movable portion first layer conductive coil inner end portion 27a. The second movable portion second layer conductive coil outer end portion 32 b is formed near the gimbal spring at the outer end of the second movable portion 23. 33 is an electrode for connecting the second movable portion first layer conductive coil outer end portion 27b, is formed near the gimbal spring at the outer end of the second movable portion 23, and is laminated directly on the second movable portion first layer conductive coil outer end portion 27b. Is done.
[0018]
Next, an insulating layer is formed on the surface, and the portion where the second layer coil and the connection electrode pattern are directly laminated is removed. A metal thin film is formed thereon. A resist is applied to the upper surface of the metal thin film, and a mask on which a connection electrode pattern is formed is overlaid and exposed. The portion that becomes the opening of the resist is removed, and the metal thin film is etched. The connection electrode pattern shown in FIG. 5 can be formed by removing the resist. Reference numerals 34 and 35 denote first movable part driving conductive coil connection electrodes, and the connection terminal 34 a is connected to the first movable part first layer conductive coil outer end 24 b via the connection electrode 31. The connection terminal 35a is connected to the first movable part second layer conductive coil outer end part 29b. The connection terminals 34b and 35b are connected to the first movable part drive power supply. Reference numerals 36 and 37 denote second movable part driving conductive coil connection electrodes, and the connection terminal 37 a is connected to the second movable part first layer conductive coil outer end part 27 b via the connection electrode 33. The connection terminal 36a is connected to the second movable part second layer conductive coil outer end part 32b. The connection terminals 36b and 37b are connected to the second movable part drive power supply.
[0019]
FIG. 6A is a plan view of the completed galvanometer mirror, and FIG. In FIG. 6B, on the right side of the second movable portion 23, the first layer conductive coil 27, the insulating layer 38, the second layer conductive coil 32, the insulating layer 38, and the connection electrode 34 are laminated on the substrate 21. Yes. Further, a protective film (not shown) is formed thereon. Although shown roughly in the figure, each film thickness is actually about 1 μm. The width of the conductive coil is about 40 μm, the distance between the coils is about 10 μm, and the number of turns is about 15 turns. Needless to say, the specifications of the conductive coil vary depending on the deflection angle of the galvanometer mirror, the strength of the magnet, and the like.
[0020]
[Problems to be solved by the invention]
A conductive layer (coil, connection electrode) is laminated via an insulating layer, and wiring is complicated. The insulating layer is formed by applying photosensitive polyimide or evaporating SiO ₂ . It is difficult to form an insulating thin film uniformly on a conductive coil pattern with dense irregularities by spinner or sputtering, and insulation failure may occur.
[0021]
Similarly, it is difficult to apply the resist uniformly, and variations in pattern width are likely to occur.
[0022]
Since a laminated film is formed only on one surface of the substrate, the substrate is likely to warp, and the characteristics of the galvano element are deteriorated.
[0023]
[Means for Solving the Problems]
One substrate is provided with a frame-shaped fixed portion, an outer peripheral movable portion provided inside the fixed portion and rotatably supported by a pair of outer spring portions, and provided inside the outer peripheral movable portion. The outer spring part is formed with a center side movable part rotatably supported by a pair of inner spring parts whose axial directions are orthogonal to each other, and a reflecting mirror is formed on the center side movable part. In the optical deflection element configured by forming a conductive coil pattern on the movable portion, the conductive coil pattern of the outer peripheral movable portion is formed on one surface of the outer peripheral movable portion, and the central movable portion is The light deflection element forms a conductive coil pattern of the central movable portion on a surface opposite to one surface of the outer peripheral movable portion .
[0024]
The spring part and the two movable parts are optical deflecting elements having substantially the same thickness as the substrate.
[0025]
The outer peripheral side movable portion is an optical deflection element in which an auxiliary pattern for suppressing warpage and distortion of the substrate is formed on the other surface of the outer peripheral side movable portion .
[0026]
One substrate is provided with a frame-shaped fixed portion, an outer peripheral movable portion provided inside the fixed portion and rotatably supported by a pair of outer spring portions, and provided inside the outer peripheral movable portion. The outer spring part is formed with a center side movable part rotatably supported by a pair of inner spring parts whose axial directions are orthogonal to each other, and a reflecting mirror is formed on the center side movable part. in the method for manufacturing an optical deflection element to form a conductive coil pattern on a moving part, on one surface of the outer peripheral side movable portion, to form a conductive coil pattern of the outer peripheral side movable portion, the other surface of the outer peripheral-side movable portion In addition, an auxiliary pattern for suppressing warpage and distortion of the substrate is formed, and a conductive coil pattern of the central movable portion is formed on the other surface side surface of the central movable portion .
[0027]
DETAILED DESCRIPTION OF THE INVENTION
The manufacturing method of the optical deflection element of the present invention will be described with reference to FIGS. 7 is a first layer pattern diagram of the surface, a plan view and a sectional view, and FIG. 8 is a second layer pattern diagram and a plan view. In this example as well, a conductive coil pattern is formed on a gimbaled substrate. FIG. 9 is a first layer pattern diagram of the back surface, a plan view and a cross-sectional view, and FIG. 10 is a second layer pattern diagram and a plan view.
[0028]
A metal thin film (preferably aluminum) is formed on the surface of the single crystal silicon substrate 21 by sputtering, vapor deposition or the like. A resist is applied on the upper surface of the metal thin film, and a mask on which a conductive coil pattern of the first layer is formed is overlaid and exposed. The portion that becomes the opening of the resist is removed, and the metal thin film is etched. By removing the resist, the first layer conductive coil pattern of FIG. 7 is formed.
[0029]
A first movable portion first layer conductive coil 40 is formed on the first movable portion 22, and second movable portion auxiliary patterns 41 and 42 are formed on the second movable portion 23. The first movable portion first layer conductive coil inner end portion 40a is formed at the center of the first movable portion 22, and the first movable portion second layer conductive coil inner end portion 43a (FIG. 8) is directly laminated. The first movable portion first layer conductive coil outer end portion 40 b is connected to the connection electrode 46 through the auxiliary pattern 42 of the second movable portion 23.
[0030]
Next, an insulating layer is formed on the surface with photosensitive polyimide, SiO ₂ or the like, and a portion where the first layer conductive coil and the second layer conductive coil are directly laminated is removed. A metal thin film is formed thereon. A resist is applied to the upper surface of the metal thin film, and a mask on which a second-layer conductive coil pattern is formed is overlaid and exposed. The portion that becomes the opening of the resist is removed, and the metal thin film is etched. By removing the resist, the conductive coil pattern of the second layer in FIG. 8 is formed.
[0031]
A first movable portion second layer conductive coil 43 is formed on the first movable portion 22, and second movable portion auxiliary patterns 44 and 45 are formed on the second movable portion 23. The first movable part second layer conductive coil inner end 43a is formed at the center of the first movable part 22, and is directly laminated on the first movable part first layer conductive coil inner end 40a (FIG. 7). The first movable portion second layer conductive coil outer end portion 43b is connected to the connection electrode 47 through the auxiliary pattern 44 of the second movable portion.
[0032]
Next, a metal thin film (preferably aluminum) is formed on the back surface of the single crystal silicon substrate 21 by sputtering, vapor deposition, or the like. A resist is applied on the upper surface of the metal thin film, and a mask on which a conductive coil pattern of the first layer is formed is overlaid and exposed. The portion that becomes the opening of the resist is removed, and the metal thin film is etched. By removing the resist, the first layer conductive coil pattern of FIG. 9 is formed.
[0033]
A second movable portion first layer conductive coil 48 is formed in the second movable portion 23. The second movable portion first layer conductive coil inner end portion 48a is formed at the inner edge of the second movable portion 23, and the second movable portion second layer conductive coil inner end portion 49a (FIG. 10) is directly laminated. The connection electrode 50 and the auxiliary electrode 51 are formed in the same manner as in the prior art. The outer end of the second movable part first layer conductive coil is connected to the connection electrode 52.
[0034]
Next, an insulating layer is formed on the surface with photosensitive polyimide, SiO ₂ or the like, and a portion where the first layer conductive coil and the second layer conductive coil are directly laminated is removed. A metal thin film is formed thereon. A resist is applied to the upper surface of the metal thin film, and a mask on which a second-layer conductive coil pattern is formed is overlaid and exposed. The portion that becomes the opening of the resist is removed, and the metal thin film is etched. By removing the resist, the conductive coil pattern of the second layer in FIG. 10 is formed.
[0035]
A second movable portion second layer conductive coil 49 is formed on the second movable portion 23, and a reflecting mirror (galvano mirror) 54 is formed on the first movable portion 22. The second movable portion second layer conductive coil inner end portion 49a is formed at the inner edge of the second movable portion, and is directly laminated on the second movable portion first layer conductive coil inner end portion 48a (FIG. 9). The outer end of the second movable part second layer conductive coil is connected to the auxiliary electrode 50 and further connected to the connection electrode 53. 55 is an auxiliary electrode. When the conductive pattern is formed on the front and back of the substrate as in the present invention, the spring portion that supports the substrate and the movable portion is designed to have the same thickness or a difference that does not hinder the formation of an insulating film or a resist film. preferable.
[0036]
FIG. 11 is a plan view and a cross-sectional view of the optical deflection element manufactured by the above-described process as seen from the back. Further, whether or not a protective film is formed on the surface is appropriately determined.
[0037]
【The invention's effect】
Since the conductive coils formed on the first movable part and the second movable part are separated on the front and back sides of the substrate, wiring is facilitated, and connection electrodes crossing the conductive coil pattern are not required, so that it is possible to prevent the occurrence of show and defects.
[0038]
The galvano element can be easily manufactured by making the spring part supporting the substrate and the movable part have the same thickness or a difference that does not hinder the formation of the insulating film or the resist film.
[0039]
By forming an auxiliary pattern that opposes the conductive coil pattern on the back surface of the conductive coil pattern of the movable part, substantially equal films are formed on both surfaces of the substrate, and warping and distortion of the movable part can be minimized.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating a principle structure of an optical deflection element according to the present invention. FIG. 2 is an example of realizing the principle structure. FIG. 3 is a diagram for explaining the formation of a conductive coil pattern of a biaxial optical deflection element according to the prior art. FIG. 4 is a diagram for explaining conductive coil pattern formation of a biaxial light deflection element according to the prior art, and FIG. 5 is a plan view. FIG. 5 is a diagram illustrating conductive coil pattern formation of a biaxial light deflection element according to the prior art. FIG. 6 is a plan view of the completed galvanometer mirror (a) and a schematic diagram of a side cross-section taken along the line AA.
7 is a first layer pattern diagram of the front surface, a plan view and a cross-sectional view. FIG. 8 is a second layer pattern diagram and a plan view. FIG. 9 is a first layer pattern diagram of the back surface, a plan view and a cross-sectional view. 10 is a plan view of the second layer pattern diagram. FIG. 11 is a plan view and a cross-sectional view of an optical deflection element.
1 Substrate (silicon single crystal)
DESCRIPTION OF SYMBOLS 1 'Movable part 2 Gimbal spring 3 Galvano mirror 4 Conductive coil 5 X direction axis 6 Y direction axis 7 X direction magnetic field 8 Y direction magnetic field 9 Electrode pad 9' End of electrode pad 10 Insulating film 11 Conductive layer 12 Support point 12 'Support point 13 fulcrum 13 'fulcrum 14 outermost shell end 15 innermost shell end 21 substrate 22 first movable part 23 second movable part 24 first movable part first layer conductive coil 24a first movable part in first layer conductive coil End 24b First movable portion First layer conductive coil outer end 25 First movable portion First layer conductive coil auxiliary electrode 26 Second layer connection electrode 27 Second movable portion First layer conductive coil 27a Second movable portion 1st layer conductive coil inner end portion 27b second movable portion first layer conductive coil outer end portion 28 second movable portion first layer conductive coil second layer connection electrode 29 first movable portion second layer conductive coil 29a first movable portion Second layer conductive coil inner end 29b First movable part Second layer conductive coil outer end 30 First movable portion Second layer conductive coil auxiliary electrode 31 First layer connection electrode 32 Second movable portion Second layer conductive coil 32a Second movable portion Second layer conductive coil inner end 32b Second movable part second layer conductive coil outer end 33 Second movable part Second layer conductive coil 21st connection electrode 34 First movable part drive conductive coil connection electrode 34a Connection terminal 34b Connection terminal 35 First movable part Driving conductive coil connection electrode 35a Connection terminal 35b Connection terminal 36 Second movable part driving conductive coil connection electrode 36a Connection terminal 36b Connection terminal 37 Second movable part driving conductive coil connection electrode 37a Connection terminal 37b Connection terminal 38 Insulating film 40 First movable portion First layer conductive coil 40a First movable portion First layer conductive coil inner end portion 40b First movable portion First layer conductive coil outer end portion 41 Second movable portion auxiliary pattern 42 Second movable portion Auxiliary pattern 43 First movable part second layer conductive coil 43a First movable part Second layer conductive coil inner end 43b First movable part Second layer conductive coil inner end 44 Second movable part auxiliary pattern 45 Second movable part Auxiliary pattern 46 Connection electrode 47 Connection electrode 48 Second movable part first layer conductive coil 48a Second movable part first layer conductive coil inner end 49 Second movable part second layer conductive coil 49a Second movable part second layer conductive Coil inner end 50 Connection electrode 51 Auxiliary electrode 52 Connection electrode 53 Connection electrode 54 Reflecting mirror 55 Auxiliary electrode

Claims

One substrate is provided with a frame-shaped fixed portion, an outer peripheral movable portion provided inside the fixed portion and rotatably supported by a pair of outer spring portions, and provided inside the outer peripheral movable portion. The outer spring part is formed with a center side movable part rotatably supported by a pair of inner spring parts whose axial directions are orthogonal to each other, and a reflecting mirror is formed on the center side movable part. In an optical deflection element configured by forming a conductive coil pattern on a movable part,
A conductive coil pattern of the outer periphery-side movable portion is formed on one surface of the outer periphery-side movable portion, and the center-side movable portion is movable on the surface opposite to the one surface of the outer periphery-side movable portion. Forming a conductive coil pattern of a portion .

2. The optical deflection element according to claim 1, wherein the spring part and the two movable parts have substantially the same thickness as the substrate.

The optical deflection element according to claim 1, wherein the outer peripheral side movable portion is formed with an auxiliary pattern for suppressing warpage and distortion of the substrate on the other surface of the outer peripheral side movable portion .

One substrate is provided with a frame-shaped fixed portion, an outer peripheral movable portion provided inside the fixed portion and rotatably supported by a pair of outer spring portions, and provided inside the outer peripheral movable portion. The outer spring part is formed with a center side movable part rotatably supported by a pair of inner spring parts whose axial directions are orthogonal to each other, and a reflecting mirror is formed on the center side movable part. In a method of manufacturing an optical deflection element that forms a conductive coil pattern on a movable part,
A conductive coil pattern of the outer peripheral side movable portion is formed on one surface of the outer peripheral side movable portion, and an auxiliary pattern for suppressing warpage and distortion of the substrate is formed on the other surface of the outer peripheral side movable portion, and the center The side movable part is formed by forming a reflecting mirror on one surface side surface of the outer peripheral side movable part, and forming a conductive coil pattern of the center side movable part on the other surface side surface of the outer peripheral side movable part. A manufacturing method of a light deflection element characterized in that.