JP3547393B2

JP3547393B2 - Solid-state imaging device and imaging system using the same

Info

Publication number: JP3547393B2
Application number: JP2000355584A
Authority: JP
Inventors: 康弘森中; 寛仁菰渕; ▲琢▼己山口; 静鈴木
Original assignee: Panasonic Corp; Matsushita Electric Industrial Co Ltd
Current assignee: Panasonic Corp; Panasonic Holdings Corp
Priority date: 1999-11-22
Filing date: 2000-11-22
Publication date: 2004-07-28
Anticipated expiration: 2020-11-22
Also published as: JP2002170947A

Description

【０００１】
【発明の属する技術分野】
本発明は、固体撮像素子およびそれを用いた撮像システムに関する。本発明は、特に、高速読み出しが可能な固体撮像素子に適した素子構造を提供する。
【０００２】
【従来の技術】
撮像素子において画像データを高速に読み出す１つの手段として、光電変換領域を複数の区域に分割し、各区域から並列に電荷を読み出す方法がある。例えば、特開平３−２２４３７１号公報では、読み出しアンプを互いにミラー対称（線対称）に配置した構造（図１０）が提案されている。この固体撮像素子では、画素部３１，３２において行列状に配置された各画素から、水平電荷転送路３３と、水平電荷転送路の両端に配置された読み出しアンプ３４，３５とをこの順に介して、信号が出力される。
【０００３】
【発明が解決しようとする課題】
しかしながら、読み出しアンプ３４，３５を互いにミラー対称に配置すると、トランジスタレベルでは、ソース（Ｓ）とドレイン（Ｄ）とを、ゲート（Ｇ）を中心として、ミラー対称に配置しなければならない（図１１（ｂ））。このため、半導体製造のマスク合わせ工程において生じたアライメントずれが、不純物イオン注入工程における注入角依存性の影響と相俟って、均一な入出力特性を有する読み出しアンプの作製を困難とする。
【０００４】
読み出しアンプの特性の相違は、画像を再現した場合、画像がブロック化して観察されるという不具合を生じさせる。さらに、読み出したデータを組み合わせて１枚の画像として表示するときに、メモリ等を用いた画像データの並べ替えが必要となるため、信号処理が複雑化する。図１１（ａ）の配置では、リソグラフ工程のマスクずれ等は、異なるアンプに対して同等に影響するため、アンプ間の特性差を生じさせる原因とはならない。しかし、図１１（ｂ）の配置では、製造工程におけるイオン注入やマスク合わせのずれが、異なるアンプ間で異なる効果を生じさせ、アンプ間の特性差を生じさせる。
【０００５】
本発明は、上記従来の問題を解決するため、半導体製造のマスクの合わせずれやイオン注入角度に影響されにくい構造を有し、かつ複数のアンプで信号を読み出して１枚の画像として表示する場合にも、信号処理が簡単である固体撮像素子の構造を提供することを目的とする。
【０００６】
【課題を解決するための手段】
前記目的を達成するため、本発明の固体撮像素子は、垂直方向および水平方向に沿って行列状に配置された複数の光電変換部および前記光電変換部の列に沿って伸長する複数の垂直電荷転送路を含み、垂直方向に沿って複数の光電変換ブロックに分割された光電変換領域と、前記複数の光電変換ブロックごとに前記複数の垂直電荷転送路から信号を受け取る複数の水平電荷転送路と、前記複数の光電変換ブロックと前記複数の水平電荷転送路との間にそれぞれ配置された複数の垂直／水平変換部と、前記複数の水平電荷転送路からそれぞれ信号を受け取る複数の読み出しアンプとを含む固体撮像素子であって、前記複数の垂直電荷転送路を、水平方向について、前記光電変換領域内ではピッチＡで配列し、前記水平電荷転送路に信号を入力する部分では前記ピッチＡよりも狭いピッチＢで配列し、前記複数の垂直／水平変換部を前記光電変換ブロックから前記水平電荷転送路に近づくにつれてそれぞれ絞り込んでいくことにより生じた空き領域を利用して、前記複数の読み出しアンプを、それぞれ対応する水平電荷転送路の最終段に隣接して配置し、前記複数の読み出しアンプを、それぞれ、その構成部材が同一の位置関係を保つように配置し、前記複数の垂直電荷転送路の水平方向についてのそれぞれの幅を、前記光電変換領域の端部から前記水平電荷転送路の端部にかけて、一定、または前記光電変換領域から前記水平電荷転送路に近づくにつれて増加させた、ことを特徴とする。
【０００７】
【発明の実施の形態】
本発明の固体撮像素子では、光電変換領域における垂直電荷転送路のピッチＡに対し、水平電荷転送路に信号を入力する部分における垂直電荷転送路のピッチＢが狭くなっている（Ａ＞Ｂ）。したがって、垂直電荷転送路のライン数がＮであるときに、（Ｎ−１）×（Ａ−Ｂ）で示される幅を有するスペースＳが生じる。このスペースＳは、読み出しアンプを配置する領域として利用できる。そして、光電変換領域を複数の区域に分割して区域ごとに読み出しアンプを配置する場合にも、上記スペースＳを利用すれば、複数の読み出しアンプを、一方から他方に互いに平行移動により移動できる関係が保たれるように、配置できる。互いに平行移動により移動できる位置関係は、例えば図１１（ａ）に例示されている。
【０００８】
このように配置すれば、製造工程におけるアライメントずれや不純物の注入角度の影響を抑制できる。また、周辺回路や、この回路に至る配線も、同一パターンとできるため、これら回路や配線による特性差も解消しやすくなる。さらに、信号処理に関しても、１つの読み出しアンプに対応する光電変換領域の各区域（光電変換ブロック）を、互いに同一形状であって、対応する画素の水平読み出し方向も同一となるように配置できる。したがって、画素をミラー対称に配置した場合に必要となるデータ並び替えの煩雑さが解消された固体撮像素子を得ることができる。
【０００９】
本発明の好ましい形態では、固体撮像素子は、光電変換領域を垂直方向に沿って分割した区域ごとに（換言すれば光電変換ブロックごとに）、この区域内の垂直電荷転送路から信号を受け取る水平電荷転送路および読み出しアンプが配置される。この場合は、上記スペースＳを利用することにより、水平方向について、光電変換領域を分割した区域の幅以下の幅に、当該区域内の垂直電荷転送路から信号を受け取る水平電荷転送路および読み出しアンプを配置することが好ましい。この好ましい形態は、光電変換ブロックの水平方向への配置数を制限しない構造を実現する。さらに具体的には、光電変換領域を分割した区域（光電変換ブロック）、この区域から信号を受け取る水平電荷転送路および読み出しアンプを１つの固体撮像ブロックとして、実質的に同一形状の複数の固体撮像ブロックを、水平方向に沿って配列するとよい。均一な画像を得やすくなるからである。
【００１０】
さらに、光電変換ブロックの境界においても、垂直電荷転送路を水平方向にピッチＡで配列すると、画像の歪み等の解消に有利である。
【００１１】
垂直電荷転送路の水平方向についての幅は、光電変換領域の端部から水平電荷転送路の端部にかけて実質的に一定とすることが好ましいが、光電変換領域の端部から水平電荷転送路の端部にかけて徐々にまたは段階的に増加させてもよい。
【００１２】
上記垂直電荷転送路の典型的な形態では、平面視で観察したときに折り曲げ部分（屈曲部分）が観察される。この場合は、屈曲部分において転送劣化が発生することがあるが、この転送劣化は、いくつかの方法により抑制できる。
【００１３】
例えば、少なくとも垂直電荷転送路の屈曲部分に、垂直電荷転送路の他の部分とは独立して転送駆動パルスを印加できるように配線された複数の転送電極を、上記垂直電荷転送路上に配置するとよい。この配置を採用すれば、屈曲部分に独立して適切な転送パルスを与えることができるようになる。
【００１４】
また、通常は、垂直電荷転送路の屈曲部分が、転送電極の下方に存在するより転送電極間の下方に位置するように複数の転送電極を配置することが好ましい。しかし、屈曲部分が所定の転送電極の下方に位置する場合であっても、この所定の転送電極により転送駆動パルスが印加される転送路長さが、上記所定の転送電極に隣接する転送電極により転送駆動パルスが印加される転送路長さよりも短くするとよい。
【００１５】
また、屈曲部分の屈曲角は、最大でも４５度以下とすることが好ましい。複数の垂直電荷転送路のピッチを徐々に減少させながら、この一群の垂直電荷転送路を両端から中央へと絞り込んでいく場合、両端の垂直電荷転送路において屈曲角が最大となる。この典型的な一形態を適用する光電変換ブロックでは、ブロック端部の垂直電荷転送路の屈曲角を４５度以下とすればよい。
【００１６】
以下、本発明の実施形態について、図１から図８を参照して説明する。
（実施の形態１）
図１は本発明の実施の形態１に係るＣＣＤ型固体撮像素子の構成を示したものである。この固体撮像素子では、各光電変換ブロック１１，１２・・・１３に、行列状（マトリックス状、２次元アレイ状）にフォトダイオード（光電変換部）１が形成されており、フォトダイオードの列の間において垂直電荷転送路（ＶＣＣＤ）２が列方向に伸長している。
【００１７】
この固体撮像素子では、各光電変換ブロック１１，１２・・・１３と水平電荷転送路（ＨＣＣＤ）１７，１８・・・１９との間に、垂直／水平変換部（Ｖ−Ｈ変換部）１４，１５・・・１６が形成されている。各水平電荷転送路は、読み出しアンプ３１ａ，３１ｂ・・・３１ｃに接続している。読み出しアンプは、垂直電荷転送路の絞り込みによって生じたスペースを利用して、水平電荷転送路の最終段に最隣接して配置されている。このため、ＦＤＡ（フローティングディフュージョンアンプ）の寄生容量を大きく低減して、アンプの高感度化を実現できる。各光電変換ブロック領域で生成した信号電荷は、垂直電荷転送路から、水平電荷転送路を経て読み出しアンプへと転送されていく。
【００１８】
この固体撮像素子の垂直電荷転送路２は、各光電変換ブロック内では、水平方向について同一間隔を保つように配置されている。また、各ブロックの境界（継ぎ目）部分３においても、垂直電荷転送路の水平方向の間隔は一定に保たれている。したがって、この固体撮像素子では、光電変換領域全域において、垂直電荷転送路の水平方向の間隔は同一である。一方、Ｖ−Ｈ変換部１４，１５・・・１６内では、水平電荷転送路の間隔は一定ではない。
【００１９】
図２は、図１の領域Ｐ近傍の拡大図である。光電変換領域では垂直電荷転送路２は、ピッチＡを保つように配列している。水平電荷転送路に接する端部では、垂直電荷転送路２は、ピッチＢ（Ａ＞Ｂ）を保つように配列している。ここで、ピッチＢは、ピッチＡよりも例えば４０〜８０％の範囲だけ狭くするとよい。なお、信号電荷は、転送電極４１〜５４への駆動パルスの印加により、垂直電荷転送路内を順次図示下方へと転送されていく。転送電極は、例えばシリコン多結晶膜により形成される。
【００２０】
垂直電荷転送路を急激に折り曲げると、転送劣化が生じるおそれがある。好ましい折曲げ角度θは４５度以下である。また、転送路に歪みが生じた部分で転送劣化が生じないように、この部分には独立パルスを印加できるように配線するとよい。図２の形態では、少なくとも電極４３，４４に、他の電極とは独立にパルスを印加できるような配線を備えた電極構造とすることが好ましい。
【００２１】
以上のように、図示下方の水平電荷転送路に近づくにつれて垂直電荷転送路が絞り込まれていく台形状のＶ−Ｈ変換部を利用することにより、空き領域３１ｄが生じ、この空き領域にアンプを配置できるようになる。この固体撮像素子では、水平電荷転送路における電荷転送方向が同一方向である。そして、この転送路の後段に、同一形状のアンプが、構成部材が同一の位置関係を保つように配置される（図１１（ａ）参照）。
【００２２】
この固体撮像素子において、信号が伝送されていく一組の領域、例えば、光電変換領域１１、Ｖ−Ｈ変換部１４、水平電荷転送路１７および読み出しアンプ３１ａからなる素子内領域を一つの固体撮像ブロックと見れば、素子全体としては、固体撮像ブロックが水平方向につらなった構成となっている。これらの固体撮像ブロックは、同一形状で、互いに順次平行移動した位置関係を保っている。これらの固体撮像ブロックは、さらにチップ上において外部と接続するパッドに至る配線パターンを除いては、基本的に、全く同一の形状とすることができる。したがって、画像の均一性を保持する上で格段に有利である。
【００２３】
こうして得た固体撮像素子は、半導体製造のマスクの合わせずれやイオン注入角度に影響されにくく、複数のアンプで信号を読み出して１枚の画像として表示する場合にも信号処理が簡単である。
【００２４】
上記形態では、各要素が十分合理的に配置されているが、敢えて言うならば、転送電極４１〜５４を形成するために用いられている領域３１ｅにまでアンプを配置できれば、さらにアンプ配置可能領域を広げることができる。しかし、このスペース３１ｅは、次に示す実施形態により利用可能となる。
【００２５】
（実施の形態２）
図３は本発明の実施の形態２に係るＣＣＤ型固体撮像素子の構成を示したものである。この固体撮像素子でも、実施の形態１と同様、フォトダイオード１、垂直電荷転送路２を配置した光電変換ブロック２１，２２・・・２３ごとに、水平電荷転送路２７，２８・・・２９および読み出しアンプ３２ａ，３２ｂ・・・３２ｃが配置されている。また、各光電変換ブロックと水平転送電極との間に、Ｖ−Ｈ変換部２４，２５・・・２６が形成されている。
【００２６】
この固体撮像素子では、垂直電荷転送路２に沿って配線２０が形成されている。この配線は、適宜形成されたコンタクトホールを介して、下方の転送電極（図示せず）に駆動パルスを供給する。コンタクトホールは、採用される駆動パターンに応じて所定の間隔で形成される。
【００２７】
図３の領域Ｑ近傍の拡大図である図４に示すように、配線２０は、Ｖ−Ｈ変換部においても、垂直電荷転送路２に沿って配置されている。このため、各転送電極４１〜５４を水平方向に連結する必要がなくなり、固体撮像ブロック間のＶ−Ｈ変換部において、分割した転送電極４５〜５４を形成できる。したがって、この形態を利用すれば、実施の形態１ではデッドスペースであった領域３２ｅを、領域３２ｄとともに読み出しアンプの配置に利用できる。
【００２８】
以上では、２つの実施形態を例示して本発明の固体撮像素子について説明したが、この素子のさらに好ましい形態や応用例について、以下、さらに説明を続ける。
【００２９】
Ｖ−Ｈ変換部では、垂直電荷転送路の幅を、いわゆるナローチャンネル効果を防ぐために、同一幅とするとよい。図５（ａ）を参照すると、この転送路では、光電変換領域における幅Ｕ_１と水平電荷転送路に接続する部分における幅Ｖ_１とが等しい（Ｕ_１＝Ｖ_１）。さらに、Ｖ−Ｈ変換部内に任意の場所における幅Ｗ_１も等しい（Ｕ_１＝Ｗ_１＝Ｖ_１）。
【００３０】
ナローチャンネル効果を防ぐためには、図５（ｂ）に示すように、転送路の幅を、光電変換領域から水平電荷転送路へと近づくにつれて広くしてもよい（Ｕ_２＜Ｗ_２＜Ｖ_２）。ここでは、転送路の幅を徐々に広げた例を示したが、幅は、段階的に広げていっても構わない。
【００３１】
このように、Ｕ≦Ｖの関係が成立するように、転送路の幅を設計することが好ましいが、さらに具体的には、Ｖは、Ｕを基準として、１．０〜１．５倍が好適である。
【００３２】
さらに図６に、上記固体撮像素子を用いた、撮像システムの一例を示す。複数の読み出しアンプから伝送路６１，６２・・・６３を通じて並列的に読み出された信号は、ＣＤＳ（相関２重サンプリング）、ゲイン調整、ＡＤＣ（アナログ・デジタル変換）を行った後に、さらに異なる読み出しアンプによる継ぎ目部分補正と、並列読み出しによるパラレルデータのシリアル変換、色処理等を行い、メモリコントローラを介してモニタへの表示やメモリへの蓄積が行われる。これにより、境界のない均一な画像が得られる。
【００３３】
図７は、上記固体撮像素子の垂直電荷転送路７０とその上方に配置した垂直転送電極７１，７２，７３の断面斜視図である。この垂直転送電荷路７０は、上方から観察すると、幅Ｗを有する転送路７０における折れ曲がり角θの屈曲点Ｆが転送電極７２，７３間に存在する（図８（ａ））。このように電極間に相当する位置で転送路を屈曲させると転送劣化が生じにくい。一方、転送路７０の屈曲点Ｆを転送電極７２の下方に配置すると、この転送電極７２の下方において転送劣化が生じやすくなる（図８（ｂ））。なお、図７では、転送電極７１〜７３を２層のポリシリコン膜で構成した例を示したが、電極は３以上の層構成としてもよい。また、転送電極の積層順序も図７に示した形態に限らない。転送電極７２を両隣の転送電極７１，７３の上方から形成しても構わない。
【００３４】
しかし、図９に示すように、屈曲点を電極直下に形成しても、転送パケットを例えばいわゆる２・３転送等で行い、かつ転送電極７２のゲート長を両端の電極７１，７３よりも短くすれば、転送劣化を抑制できる（Ｌ_１＞Ｌ_２，Ｌ_３＞Ｌ_２）。具体的には、ゲート幅Ｗが１〜３μｍであれば、Ｌ_２は、他の転送電極の長さＬよりも１μｍ程度短いとよい。また、電荷容量を確保するためには、同じくゲート幅Ｗが１〜３μｍのとき、Ｌ_１およびＬ_３は、他の転送電極の長さＬよりも３μｍ程度長いことが好ましい。
【００３５】
【発明の効果】
以上説明したように、本発明によれば、並列読み出しにより信号電荷を高速に読み出し、かつ半導体製造のマスク合わせ工程におけるアライメントずれや不純物ドープの注入角度依存性によるアンプ入出力特性のバラツキの抑制が容易である固体撮像素子を提供できる。また、読み出しアンプを含めた固体撮像ブロックを、同一形状でかつ平行に配列することができるため、１画面に表示する場合に、ミラー対称等で読み出した場合に必要となる煩雑なデータの並び替えを省略できるため、信号処理が容易となる。しかも、この固体撮像素子は、垂直電荷転送路の絞り込みによって生じたスペースを利用して各水平電荷転送路の最終段に読み出しアンプを隣接して配置できるため、アンプ高感度化の観点からも有利である。
【図面の簡単な説明】
【図１】本発明の固体撮像素子の構成例を示す図である。
【図２】図１の領域Ｐの拡大図である。
【図３】本発明の固体撮像素子の別の構成例を示す図である。
【図４】図２の領域Ｑの拡大図である。
【図５】（ａ）、（ｂ）とも、垂直電荷転送路の線路幅を説明するための平面図である。
【図６】本発明の撮像システムの構成例を示すブロック図である。
【図７】本発明の固体撮像素子の垂直電荷転送路とその上方の構造を示す部分切り取り斜視図である。
【図８】（ａ）、（ｂ）とも、本発明の固体撮像素子の垂直電荷転送路の屈曲部近傍の例を示す平面図である。
【図９】本発明の固体撮像素子の垂直電荷転送路の屈曲部近傍の別の例を示す平面図である。
【図１０】従来の固体撮像素子の構成例を示す図である。
【図１１】アライメントやイオン注入角のずれによるアンプ形状の相違を示す図である（（ａ）では、互いに平行移動による位置関係を有する一対のトランジスタを、（ｂ）では、互いにミラー対称（線対称）である位置関係を有する一対のトランジスタをそれぞれ例示）。
【符号の説明】
１フォトダイオード（光電変換部）
２垂直電荷転送路（ＶＣＣＤ）
３ブロック境界部分
１１，１２，１３，２１，２２，２３光電変換ブロック
１４，１５，１６，２４，２５，２６垂直／水平変換部（Ｖ−Ｈ変換部）
１７，１８，１９，２７，２８，２９水平電荷転送路（ＨＣＣＤ）
２０配線
３１ａ〜ｃ，３２ａ〜ｃ読み出しアンプ
４１〜５４転送電極
７０垂直電荷転送路（ＶＣＣＤ）
７１，７２，７３垂直転送電極[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a solid-state imaging device and an imaging system using the same. The present invention particularly provides an element structure suitable for a solid-state imaging device capable of high-speed reading.
[0002]
[Prior art]
As one means for reading image data at high speed in an image sensor, there is a method in which a photoelectric conversion region is divided into a plurality of sections, and charges are read from each section in parallel. For example, Japanese Patent Application Laid-Open No. 3-224371 proposes a structure (FIG. 10) in which read amplifiers are arranged mirror-symmetrically (linearly symmetrically) with each other. In this solid-state imaging device, a horizontal charge transfer path 33 and readout amplifiers 34 and 35 disposed at both ends of the horizontal charge transfer path are arranged in this order from pixels arranged in a matrix in the pixel units 31 and 32. , A signal is output.
[0003]
[Problems to be solved by the invention]
However, if the read amplifiers 34 and 35 are arranged mirror-symmetrically to each other, at the transistor level, the source (S) and the drain (D) must be arranged mirror-symmetrically about the gate (G) (FIG. 11). (B)). For this reason, the misalignment caused in the mask alignment step of the semiconductor manufacturing, coupled with the influence of the implantation angle dependence in the impurity ion implantation step, makes it difficult to produce a read amplifier having uniform input / output characteristics.
[0004]
The difference in the characteristics of the read amplifier causes a problem in that when the image is reproduced, the image is observed as being blocked. Further, when the read data is combined and displayed as one image, it is necessary to rearrange the image data using a memory or the like, which complicates the signal processing. In the arrangement of FIG. 11A, a mask shift or the like in the lithographic process equally affects different amplifiers, and does not cause a characteristic difference between the amplifiers. However, in the arrangement shown in FIG. 11B, deviations in ion implantation and mask alignment in the manufacturing process cause different effects between different amplifiers, resulting in a difference in characteristics between the amplifiers.
[0005]
In order to solve the above-mentioned conventional problems, the present invention has a structure which is hardly affected by misalignment of a mask for manufacturing a semiconductor or an ion implantation angle, and reads out a signal with a plurality of amplifiers and displays it as one image. Another object of the present invention is to provide a structure of a solid-state imaging device in which signal processing is simple.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, the solid-state imaging device of the present invention includes a plurality of photoelectric conversion units arranged in a matrix along a vertical direction and a horizontal direction, and a plurality of vertical charges extending along a column of the photoelectric conversion units. the transfer path seen including a photoelectric conversion region divided into a plurality of photoelectric conversion blocks along a vertical direction, a plurality of horizontal charge transfer path for receiving signals from the plurality of vertical charge transfer paths for each of the plurality of photoelectric conversion blocks A plurality of vertical / horizontal conversion units respectively arranged between the plurality of photoelectric conversion blocks and the plurality of horizontal charge transfer paths; and a plurality of read amplifiers respectively receiving signals from the plurality of horizontal charge transfer paths. Wherein the plurality of vertical charge transfer paths are arranged at a pitch A in the photoelectric conversion region in the horizontal direction, and a signal is input to the horizontal charge transfer paths. The portions were arranged at a narrow pitch B than the pitch A, by utilizing the free space caused by narrowing down respectively as a plurality of vertical / horizontal conversion portions closer to the horizontal charge transfer path from the photoelectric conversion blocks The plurality of read amplifiers are respectively arranged adjacent to the last stage of the corresponding horizontal charge transfer path, and the plurality of read amplifiers are respectively arranged such that their constituent members maintain the same positional relationship, The width of each of the plurality of vertical charge transfer paths in the horizontal direction is constant from the end of the photoelectric conversion area to the end of the horizontal charge transfer path, or as the distance from the photoelectric conversion area approaches the horizontal charge transfer path. Increased .
[0007]
BEST MODE FOR CARRYING OUT THE INVENTION
In the solid-state imaging device of the present invention, the pitch B of the vertical charge transfer path in a portion where a signal is input to the horizontal charge transfer path is smaller than the pitch A of the vertical charge transfer path in the photoelectric conversion region (A> B). . Therefore, when the number of lines of the vertical charge transfer path is N, a space S having a width represented by (N−1) × (AB) is generated. This space S can be used as a region where the read amplifier is arranged. Also, in the case where the photoelectric conversion region is divided into a plurality of sections and the read amplifiers are arranged in each section, by using the space S, the plurality of read amplifiers can be moved from one side to the other side by parallel movement. Can be arranged so that FIG. 11A illustrates an example of a positional relationship that can be moved by parallel movement.
[0008]
With this arrangement, it is possible to suppress the effects of misalignment and the implantation angle of impurities in the manufacturing process. In addition, since the peripheral circuit and the wiring leading to this circuit can be formed in the same pattern, differences in characteristics between these circuits and wiring can be easily eliminated. Further, with regard to signal processing, the respective sections (photoelectric conversion blocks) of the photoelectric conversion region corresponding to one read amplifier can be arranged so as to have the same shape and the same horizontal read direction of the corresponding pixels. Therefore, it is possible to obtain a solid-state imaging device in which the complicated data rearrangement required when the pixels are arranged in mirror symmetry is eliminated.
[0009]
In a preferred embodiment of the present invention, the solid-state image pickup device includes a horizontal section for receiving a signal from a vertical charge transfer path in each area obtained by dividing the photoelectric conversion region along the vertical direction (in other words, for each photoelectric conversion block). A charge transfer path and a read amplifier are arranged. In this case, by utilizing the space S, a horizontal charge transfer path and a read amplifier for receiving a signal from a vertical charge transfer path in the area in the horizontal direction to a width equal to or less than the width of the area into which the photoelectric conversion region is divided. Is preferably arranged. This preferred embodiment realizes a structure that does not limit the number of photoelectric conversion blocks arranged in the horizontal direction. More specifically, a plurality of solid-state imaging devices having substantially the same shape are defined as an area (photoelectric conversion block) obtained by dividing a photoelectric conversion region, a horizontal charge transfer path for receiving a signal from this area, and a readout amplifier as one solid-state imaging block. The blocks may be arranged in a horizontal direction. This is because a uniform image can be easily obtained.
[0010]
Further, even at the boundaries of the photoelectric conversion blocks, arranging the vertical charge transfer paths at a pitch A in the horizontal direction is advantageous in eliminating image distortion and the like.
[0011]
The width of the vertical charge transfer path in the horizontal direction is preferably substantially constant from the end of the photoelectric conversion region to the end of the horizontal charge transfer path. It may be increased gradually or stepwise towards the end.
[0012]
In a typical form of the vertical charge transfer path, a bent portion (bent portion) is observed when observed in a plan view. In this case, transfer deterioration may occur at the bent portion, but this transfer deterioration can be suppressed by several methods.
[0013]
For example, when at least a bent portion of the vertical charge transfer path, a plurality of transfer electrodes wired so as to be able to apply a transfer drive pulse independently of the other parts of the vertical charge transfer path are arranged on the vertical charge transfer path. Good. By employing this arrangement, it is possible to apply an appropriate transfer pulse independently to the bent portion.
[0014]
Usually, it is preferable to arrange the plurality of transfer electrodes so that the bent portion of the vertical charge transfer path is located between the transfer electrodes below the transfer electrodes. However, even when the bent portion is located below the predetermined transfer electrode, the transfer path length to which the transfer drive pulse is applied by the predetermined transfer electrode is determined by the transfer electrode adjacent to the predetermined transfer electrode. It is preferable that the length be shorter than the length of the transfer path to which the transfer drive pulse is applied.
[0015]
Further, it is preferable that the bending angle of the bending portion is 45 degrees or less at the maximum. When the group of vertical charge transfer paths is narrowed from both ends to the center while gradually decreasing the pitch of the plurality of vertical charge transfer paths, the bending angle becomes maximum in the vertical charge transfer paths at both ends. In the photoelectric conversion block to which this typical embodiment is applied, the bending angle of the vertical charge transfer path at the end of the block may be 45 degrees or less.
[0016]
Hereinafter, an embodiment of the present invention will be described with reference to FIGS.
(Embodiment 1)
FIG. 1 shows a configuration of a CCD solid-state imaging device according to Embodiment 1 of the present invention. In this solid-state imaging device, photodiodes (photoelectric conversion units) 1 are formed in a matrix (in a matrix or in a two-dimensional array) in each of the photoelectric conversion blocks 11, 12,. Between them, a vertical charge transfer path (VCCD) 2 extends in the column direction.
[0017]
In this solid-state imaging device, a vertical / horizontal conversion section (VH conversion section) 14 is provided between each photoelectric conversion block 11, 12,... 13 and a horizontal charge transfer path (HCCD) 17, 18,. , 15... 16 are formed. Each horizontal charge transfer path is connected to readout amplifiers 31a, 31b,... 31c. The read amplifier is disposed closest to the final stage of the horizontal charge transfer path by utilizing the space generated by the narrowing of the vertical charge transfer path. Therefore, the parasitic capacitance of the FDA (floating diffusion amplifier) can be greatly reduced, and high sensitivity of the amplifier can be realized. The signal charge generated in each photoelectric conversion block region is transferred from the vertical charge transfer path to the read amplifier via the horizontal charge transfer path.
[0018]
The vertical charge transfer paths 2 of the solid-state imaging device are arranged so as to keep the same interval in the horizontal direction in each photoelectric conversion block. Also, at the boundary (seam) portion 3 of each block, the horizontal distance between the vertical charge transfer paths is kept constant. Therefore, in this solid-state imaging device, the vertical charge transfer paths have the same horizontal spacing throughout the photoelectric conversion region. On the other hand, the intervals between the horizontal charge transfer paths are not constant in the VH converters 14, 15,.
[0019]
FIG. 2 is an enlarged view near the region P in FIG. In the photoelectric conversion region, the vertical charge transfer paths 2 are arranged so as to keep the pitch A. At an end portion that is in contact with the horizontal charge transfer path, the vertical charge transfer paths 2 are arranged so as to maintain a pitch B (A> B). Here, the pitch B may be narrower than the pitch A by, for example, a range of 40 to 80%. The signal charges are sequentially transferred in the vertical charge transfer path downward in the figure by applying drive pulses to the transfer electrodes 41 to 54. The transfer electrode is formed of, for example, a polycrystalline silicon film.
[0020]
If the vertical charge transfer path is sharply bent, transfer deterioration may occur. The preferred bending angle θ is 45 degrees or less. In order to prevent transfer deterioration in a portion where the transfer path is distorted, wiring should be performed so that an independent pulse can be applied to this portion. In the embodiment shown in FIG. 2, it is preferable that at least the electrodes 43 and 44 have an electrode structure provided with a wiring capable of applying a pulse independently of the other electrodes.
[0021]
As described above, by using the trapezoidal VH conversion section in which the vertical charge transfer path is narrowed down as it approaches the horizontal charge transfer path below the figure, a free area 31d is created, and an amplifier is placed in this free area. Be able to place. In this solid-state imaging device, the charge transfer directions in the horizontal charge transfer path are the same. An amplifier having the same shape is arranged downstream of the transfer path so that the constituent members maintain the same positional relationship (see FIG. 11A).
[0022]
In this solid-state imaging device, a set of regions through which signals are transmitted, for example, an in-device region including the photoelectric conversion region 11, the VH conversion unit 14, the horizontal charge transfer path 17, and the readout amplifier 31a is defined as one solid-state imaging device. When viewed as a block, the entire device has a configuration in which solid-state imaging blocks are connected in the horizontal direction. These solid-state imaging blocks have the same shape and maintain a positional relationship of sequentially moving in parallel with each other. These solid-state imaging blocks can basically have exactly the same shape except for a wiring pattern that reaches pads connected to the outside on the chip. Therefore, it is extremely advantageous in maintaining the uniformity of the image.
[0023]
The solid-state imaging device obtained in this manner is hardly affected by misalignment of a mask in semiconductor manufacturing or an ion implantation angle, and signal processing is simple even when signals are read by a plurality of amplifiers and displayed as one image.
[0024]
In the above embodiment, each element is arranged reasonably enough. However, if an amplifier can be arranged up to the area 31e used for forming the transfer electrodes 41 to 54, the amplifier arrangement area is further increased. Can be expanded. However, this space 31e can be used by the following embodiment.
[0025]
(Embodiment 2)
FIG. 3 shows a configuration of a CCD solid-state imaging device according to Embodiment 2 of the present invention. In this solid-state imaging device, as in the first embodiment, the horizontal charge transfer paths 27, 28,... 29 and the photoelectric conversion blocks 21, 22,. The read amplifiers 32a, 32b,... 32c are arranged. .., 26 are formed between the photoelectric conversion blocks and the horizontal transfer electrodes.
[0026]
In this solid-state imaging device, the wiring 20 is formed along the vertical charge transfer path 2. The wiring supplies a drive pulse to a lower transfer electrode (not shown) through a contact hole formed as appropriate. The contact holes are formed at predetermined intervals according to the drive pattern to be employed.
[0027]
As shown in FIG. 4 which is an enlarged view near the region Q in FIG. 3, the wiring 20 is also arranged along the vertical charge transfer path 2 in the VH converter. For this reason, it is not necessary to connect the transfer electrodes 41 to 54 in the horizontal direction, and divided transfer electrodes 45 to 54 can be formed in the VH converter between the solid-state imaging blocks. Therefore, if this mode is used, the area 32e, which was the dead space in the first embodiment, can be used together with the area 32d for the arrangement of the read amplifier.
[0028]
In the above, the solid-state imaging device of the present invention has been described by exemplifying the two embodiments. However, further preferred embodiments and application examples of the device will be further described below.
[0029]
In the VH conversion section, the width of the vertical charge transfer path may be the same width in order to prevent a so-called narrow channel effect. Referring to FIG. 5 (a), this transfer path, the width V ₁ at a portion connecting the width U ₁ in the photoelectric conversion region to the horizontal charge transfer path are equal (U 1 _{= V} _1). Furthermore, the width _{W 1} are equal at any place on the V-H conversion portion _{_{_{(U 1 = W 1 = V}}} 1).
[0030]
In order to prevent the narrow channel effect, as shown in FIG. 5B, the width of the transfer path may be increased as approaching the horizontal charge transfer path from the photoelectric conversion region (U ₂ <W ₂ <V _2). ). Here, an example is shown in which the width of the transfer path is gradually increased, but the width may be gradually increased.
[0031]
As described above, it is preferable to design the width of the transfer path so that the relationship of U ≦ V is satisfied. More specifically, V is 1.0 to 1.5 times the value of U with respect to U. It is suitable.
[0032]
FIG. 6 shows an example of an imaging system using the solid-state imaging device. The signals read in parallel from the plurality of read amplifiers via the transmission lines 61, 62,... 63 are further different after performing CDS (correlated double sampling), gain adjustment, and ADC (analog-digital conversion). A seam portion correction by a read amplifier, serial conversion of parallel data by parallel reading, color processing, and the like are performed, and display on a monitor and accumulation in a memory are performed via a memory controller. As a result, a uniform image without boundaries can be obtained.
[0033]
FIG. 7 is a cross-sectional perspective view of the vertical charge transfer path 70 of the solid-state imaging device and the vertical transfer electrodes 71, 72, 73 disposed above the vertical charge transfer path 70. When viewed from above, the vertical transfer charge path 70 has a bending point F having a bending angle θ in the transfer path 70 having the width W between the transfer electrodes 72 and 73 (FIG. 8A). When the transfer path is bent at a position corresponding to between the electrodes, transfer deterioration is unlikely to occur. On the other hand, if the bending point F of the transfer path 70 is arranged below the transfer electrode 72, transfer deterioration tends to occur below the transfer electrode 72 (FIG. 8B). Although FIG. 7 shows an example in which the transfer electrodes 71 to 73 are formed of two layers of polysilicon films, the electrodes may have three or more layers. Further, the stacking order of the transfer electrodes is not limited to the mode shown in FIG. The transfer electrode 72 may be formed from above the transfer electrodes 71 and 73 on both sides.
[0034]
However, as shown in FIG. 9, even if the inflection point is formed immediately below the electrode, the transfer packet is performed by, for example, so-called 2.3 transfer, and the gate length of the transfer electrode 72 is shorter than the electrodes 71, 73 at both ends. Then, transfer deterioration can be suppressed (L ₁ > L ₂ , L ₃ > L ₂ ). Specifically, if the gate width W is 1 to 3 μm, L ₂ may be shorter than the length L of the other transfer electrodes by about 1 μm. Further, in order to secure the charge capacity, when the gate width W is _{1 to} 3 μm, it is preferable that L ₁ and L ₃ are longer than the length L of the other transfer electrodes by about 3 μm.
[0035]
【The invention's effect】
As described above, according to the present invention, signal charges are read at high speed by parallel reading, and variations in amplifier input / output characteristics due to misalignment in the mask alignment step of semiconductor manufacturing and implantation angle dependence of impurity doping are suppressed. An easy solid-state imaging device can be provided. Further, since the solid-state imaging blocks including the readout amplifier can be arranged in the same shape and in parallel, when displaying on one screen, complicated data rearrangement required when reading out with mirror symmetry or the like is required. Can be omitted, so that signal processing becomes easy. Moreover, in this solid-state imaging device, a readout amplifier can be arranged adjacent to the last stage of each horizontal charge transfer path by utilizing the space generated by the narrowing of the vertical charge transfer path, which is advantageous from the viewpoint of increasing the sensitivity of the amplifier. It is.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating a configuration example of a solid-state imaging device of the present invention.
FIG. 2 is an enlarged view of a region P in FIG. 1;
FIG. 3 is a diagram showing another configuration example of the solid-state imaging device of the present invention.
FIG. 4 is an enlarged view of a region Q in FIG. 2;
FIGS. 5A and 5B are plan views illustrating the line width of a vertical charge transfer path.
FIG. 6 is a block diagram illustrating a configuration example of an imaging system according to the present invention.
FIG. 7 is a partially cutaway perspective view showing a vertical charge transfer path of the solid-state imaging device of the present invention and a structure above the vertical charge transfer path.
FIGS. 8A and 8B are plan views showing examples of the vicinity of a bent portion of a vertical charge transfer path of the solid-state imaging device of the present invention.
FIG. 9 is a plan view showing another example of the vicinity of the bent portion of the vertical charge transfer path of the solid-state imaging device of the present invention.
FIG. 10 is a diagram illustrating a configuration example of a conventional solid-state imaging device.
11A and 11B are diagrams showing differences in amplifier shapes due to misalignment of an alignment or an ion implantation angle. FIG. 11A illustrates a pair of transistors having a positional relationship due to parallel movement, and FIG. A pair of transistors having a positional relationship of (symmetric).
[Explanation of symbols]
1 Photodiode (photoelectric conversion unit)
2 Vertical charge transfer path (VCCD)
3 Block boundary portions 11, 12, 13, 21, 22, 23 Photoelectric conversion blocks 14, 15, 16, 24, 25, 26 Vertical / horizontal converter (VH converter)
17, 18, 19, 27, 28, 29 Horizontal charge transfer path (HCCD)
20 Wirings 31a-c, 32a-c Readout amplifiers 41-54 Transfer electrode 70 Vertical charge transfer path (VCCD)
71,72,73 Vertical transfer electrode

Claims

Look including a plurality of vertical charge transfer paths extending along the vertical direction and the horizontal direction a plurality of which are arranged in a matrix along the photoelectric conversion unit and the photoelectric conversion portion array, a plurality of photoelectric along a vertical transform A photoelectric conversion region divided into blocks, a plurality of horizontal charge transfer paths for receiving signals from the plurality of vertical charge transfer paths for each of the plurality of photoelectric conversion blocks, the plurality of photoelectric conversion blocks and the plurality of horizontal charge transfer A solid-state imaging device including: a plurality of vertical / horizontal conversion units disposed between the plurality of horizontal charge transfer paths; and a plurality of read amplifiers each receiving a signal from the plurality of horizontal charge transfer paths .
The plurality of vertical charge transfer paths are arranged at a pitch A in the photoelectric conversion block in the horizontal direction, and are arranged at a pitch B narrower than the pitch A at a portion where a signal is input to the horizontal charge transfer path ,
In a vacant area generated by narrowing down the plurality of vertical / horizontal conversion units from the photoelectric conversion block as approaching the horizontal charge transfer path, the plurality of read amplifiers are connected to the end of the corresponding horizontal charge transfer path. Placed next to the step,
Arranging the plurality of read amplifiers such that their constituent members maintain the same positional relationship,
The width of each of the plurality of vertical charge transfer paths in the horizontal direction is constant from the end of the photoelectric conversion area to the end of the horizontal charge transfer path, or approaches the horizontal charge transfer path from the photoelectric conversion area. Increased as
A solid-state imaging device characterized by the above-mentioned.

The horizontal direction, the width equal to or smaller than that of the photoelectric conversion blocks, the solid-state imaging device according to claim 1 arranged in the horizontal charge transfer path and read amplifier receiving signals from the vertical charge transfer path of the photoelectric conversion block.

Photoelectric conversion block, the horizontal charge transfer path and read amplifier receiving signals from the photoelectric conversion blocks as one solid-state imaging block, a plurality of the solid block of the same shape, or claim 1 and arranged along the horizontal direction 3. The solid-state imaging device according to 2.

The solid-state imaging device according to claim 1, wherein vertical charge transfer paths are arranged at a pitch A in the horizontal direction even at a boundary between the plurality of photoelectric conversion blocks .

A plurality of transfer electrodes arranged so as to be able to apply a transfer drive pulse at least to a bent portion of the vertical charge transfer path independently of other portions of the vertical charge transfer path, are arranged on the vertical charge transfer path. The solid-state imaging device according to any one of claims 1 to 4 .

Solid-state imaging device according to any one of claims 1 to 5, the bent portions of the vertical charge transfer path with a plurality of transfer electrodes so as to be positioned below the transfer between the electrodes.

The bent portion of the vertical charge transfer path is located below the predetermined transfer electrode, and the length of the transfer path to which a transfer drive pulse is applied by the predetermined transfer electrode is changed by the transfer electrode adjacent to the predetermined transfer electrode. solid-state imaging device according to any one of claims 1 to 6 shorter than the transfer path length pulse is applied.

A wiring electrically connected to a plurality of transfer electrodes for applying a transfer drive pulse to the vertical charge transfer path is formed along the vertical charge transfer path, at least from the photoelectric conversion region, at a pitch of the vertical charge transfer path in the horizontal direction. The solid-state imaging device according to any one of claims 1 to 7 , wherein the solid-state imaging device is arranged over a region arranged in a region less than A.

In the vertical charge transfer paths bend angle becomes the maximum, the solid-state imaging device according to any one of claims 1 to 8 for the bending angle 45 degrees or less.

An empty area generated by narrowing down the plurality of vertical / horizontal conversion units as the distance from the photoelectric conversion block approaches the horizontal charge transfer path is reduced to transfer electrodes arranged for transferring signals in the plurality of vertical / horizontal conversion units. The solid-state imaging device according to claim 1, wherein the solid-state imaging device is expanded by dividing by a vertical / horizontal conversion unit.

Including a plurality of photoelectric conversion units arranged in a matrix along the vertical direction and the horizontal direction and a plurality of vertical charge transfer paths extending along a column of the photoelectric conversion units, a plurality of photoelectric conversion blocks along the vertical direction And a plurality of horizontal charge transfer paths for receiving signals from the plurality of vertical charge transfer paths for each of the plurality of photoelectric conversion blocks, the plurality of photoelectric conversion blocks and the plurality of horizontal charge transfer paths And a plurality of vertical / horizontal conversion units respectively disposed between A solid-state imaging device including a plurality of read amplifiers each receiving a signal from the charge transfer path,
The plurality of vertical charge transfer paths are arranged at a pitch A in the photoelectric conversion region in the horizontal direction, and are arranged at a pitch B narrower than the pitch A in a portion for inputting a signal to the horizontal charge transfer path,
In a vacant area generated by narrowing down the plurality of vertical / horizontal conversion units from the photoelectric conversion block toward the horizontal charge transfer path, the plurality of read amplifiers are connected to the end of the corresponding horizontal charge transfer path. Placed next to the step,
Arranging the plurality of read amplifiers such that their constituent members maintain the same positional relationship,
A plurality of transfer electrodes wired so that a transfer drive pulse can be applied to at least a bent portion of the vertical charge transfer path independently of other portions of the vertical charge transfer path, are arranged on the vertical charge transfer path. A solid-state imaging device characterized by the above-mentioned.

Including a plurality of photoelectric conversion units arranged in a matrix along the vertical direction and the horizontal direction and a plurality of vertical charge transfer paths extending along a column of the photoelectric conversion units, a plurality of photoelectric conversion blocks along the vertical direction And a plurality of horizontal charge transfer paths for receiving signals from the plurality of vertical charge transfer paths for each of the plurality of photoelectric conversion blocks, the plurality of photoelectric conversion blocks and the plurality of horizontal charge transfer paths A plurality of vertical / horizontal conversion units respectively disposed between the plurality of horizontal charge transfer paths, and a plurality of readout amplifiers each receiving a signal from the plurality of horizontal charge transfer paths,
The plurality of vertical charge transfer paths are arranged at a pitch A in the photoelectric conversion region in the horizontal direction, and are arranged at a pitch B narrower than the pitch A in a portion for inputting a signal to the horizontal charge transfer path,
In a vacant area generated by narrowing down the plurality of vertical / horizontal conversion units from the photoelectric conversion block toward the horizontal charge transfer path, the plurality of read amplifiers are connected to the end of the corresponding horizontal charge transfer path. Placed next to the step,
Arranging the plurality of read amplifiers such that their constituent members maintain the same positional relationship,
A plurality of transfer electrodes are arranged such that a bent portion of the vertical charge transfer path is located below between the transfer electrodes.

Including a plurality of photoelectric conversion units arranged in a matrix along the vertical direction and the horizontal direction and a plurality of vertical charge transfer paths extending along a column of the photoelectric conversion units, a plurality of photoelectric conversion blocks along the vertical direction And a plurality of horizontal charge transfer paths for receiving signals from the plurality of vertical charge transfer paths for each of the plurality of photoelectric conversion blocks, the plurality of photoelectric conversion blocks and the plurality of horizontal charge transfer paths A plurality of vertical / horizontal conversion units respectively disposed between the plurality of horizontal charge transfer paths, and a plurality of readout amplifiers each receiving a signal from the plurality of horizontal charge transfer paths,
The plurality of vertical charge transfer paths are arranged at a pitch A in the photoelectric conversion region in the horizontal direction, and are arranged at a pitch B narrower than the pitch A in a portion for inputting a signal to the horizontal charge transfer path,
In a vacant area generated by narrowing down the plurality of vertical / horizontal conversion units from the photoelectric conversion block toward the horizontal charge transfer path, the plurality of read amplifiers are connected to the end of the corresponding horizontal charge transfer path. Placed next to the step,
Arranging the plurality of read amplifiers such that their constituent members maintain the same positional relationship,
A bent portion of the vertical charge transfer path is located below a predetermined transfer electrode, and a transfer path length to which a transfer drive pulse is applied by the predetermined transfer electrode is transferred by a transfer electrode adjacent to the predetermined transfer electrode. A solid-state imaging device, wherein the length is shorter than a transfer path length to which a driving pulse is applied.

A solid-state imaging device according to claim 1, 11, 12 or 13, the solid is synthesized output from each readings out amplifiers of the imaging device, corrects the image of the joint portion corresponding to a boundary portion of the photoelectric conversion blocks And a signal processing unit for displaying one image.