Patent ID: 6569700
Filing Date: 2003-05-27
Classification: H01L

Abstract:
A method of reducing leakage current of a photodiode on a semiconductor wafer, the surface of the semiconductor wafer comprising a p-type substrate, a photosensing area for forming a photosensor of the photodiode, and a shallow trench positioned in the substrate surrounding the photosensing area, the method comprising:forming a doped polysilicon layer containing p-type dopants in the shallow trench; using a thermal process to cause the p-type dopants in the doped polysilicon layer to diffuse into portions of the p-type substrate that surround a bottom of the shallow trench and walls of the shallow trench; removing the doped polysilicon layer; filling an insulator into the shallow trench to form a shallow trench isolation (STI) structure; performing a first ion implantation process to form a first n-type doped region in the photosensing area; and performing a second ion implantation process to form a second n-type doped region in the photosensing area.