Patent ID: 9059068
Filing Date: 2015-06-16
Classification: H01L

Abstract:
1. A method for fabricating a pixel structure of a CMOS imaging sensor, comprising: providing a semiconductor substrate doped with first type doping ions; forming a hard mask layer having an opening on the semiconductor substrate; forming a trench in the semiconductor substrate by etching the semiconductor substrate using the hard mask layer as an etching mask; etching the hard mask layer to enlarge the opening to form an enlarged opening to expose a surface portion of a top surface of the semiconductor substrate around the trench; forming isolation layers on side surfaces of the trench to prevent a dark current from laterally transferring; forming an epitaxial layer doped with second type doping ions with a doping type opposite to a doping type of the first type doping ions in the trench by filling up the trench and covering the surface portion of the top surface of the semiconductor substrate around the trench, wherein a portion of the epitaxial layer is higher than the top surface of the semiconductor substrate, the portion of the epitaxial layer higher than the top surface of the semiconductor substrate is filled in the enlarged opening, and the portion of the epitaxial layer higher than the top surface of the semiconductor substrate covers the surface portion of the top surface of the semiconductor substrate exposed by the enlarged opening; forming a pinning layer on the epitaxial layer; forming a gate structure on the top surface of the semiconductor substrate at one side of the epitaxial layer; and forming a floating diffusion region in the semiconductor substrate at one side of the gate structure far from the epitaxial layer.