Patent ID: 7833814
Filing Date: 2010-11-16
Classification: H01L

Abstract:
1. A method for forming a pixel image sensor having a high shutter rejection ratio comprising the steps of: providing a substrate doped with an impurity of the first conductivity type; diffusing a moderating impurity into a surface of said substrate to form a lightly epitaxial layer of said first conductivity type; forming an isolation barrier at a relatively great depth from a surface of said substrate and beneath a storage node and storage node control transistor switches of said pixel image sensor to prevent substrate charge leakage caused by photoelectrons generated in said substrate beneath a photon sensing area of said pixel image sensor from drifting to said storage node; forming a diffusion well placed in said surface of said substrate to contact said isolation barrier; connecting said diffusion well to a first biasing voltage to channel said photoelectrons away from said storage node; forming a carrier conduction well placed at said relatively great depth within said isolation barrier to channel said substrate charge leakage to said isolation barrier, said carrier conduction well containing a photo sensing region of said pixel image sensor; and connecting said carrier conduction well to a second biasing voltage through said substrate to force said photoelectrons to collect within said photo sensing area.