A novel curved CMOS image sensor integrated with imaging system

Abstract

We realized an ultimately advanced imaging system that comprises a hemi-spherically curved, back-illuminated CMOS image sensor (BIS) and integrated lens which doubles the sensitivity at the edge of the image circle and increases the sensitivity at the center of the image circle by a factor of 1.4 with one-fifth lower dark current (J <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">d</sub> ) than that of a planar BIS. Because the lens field curvature aberration (A <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">fc</sub> ) was overcome in principle by the curved sensor itself, the curved BIS enables higher system sensitivity through design of a brighter lens with a smaller F number (F <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">n</sub> ) than is possible with a planar BIS. At the same time, we controlled the tensile stress of the BIS chip to produce a curved shape that widens the energy band-gap (E <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">g</sub> ) to obtain a lower J <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">d</sub> .