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

Abstract

A new, flattened-pear shaped photodiode structure has been developed to reduce smear and to increase photo-sensitivity in CCD image sensors. The new structure features a wide, low-concentration N- layer formed below the conventional photodiode N layer. The new photodiode was designed by using a new parameter deduced from simulated potential-profiles to help optimize the Nlayer conditions. The new structure 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 well as high sensitivity (35 nA/1x). >