A flattened-pear shaped photodiode structure for low smear and highsensitivity CCD image sensors

摘要

A new, flattened-pear shaped photodiode structure has beendeveloped to reduce smear and to increase photo-sensitivity in CCD imagesensors. The new structure features a wide, low-concentration N- layerformed below the conventional photodiode N layer. The new photodiode wasdesigned by using a new parameter deduced from simulatedpotential-profiles to help optimize the Nlayer conditions. The newstructure was applied to a 2/3-inch 2M pixel interline-transfer CCD(IT-CCD) image sensor, and it has achieved a low smear (-85 dB) as wellas high sensitivity (35 nA/1x)