Patent ID: 6534356
Filing Date: 2003-03-18
Classification: H01L

Abstract:
A method of fabricating an image sensor cell, on a semiconductor substrate, comprising the steps offorming a photodiode element, in a first portion of a semiconductor substrate, comprised of an underlying well region, of a first conductivity type, and an overlying doped region, of a second conductivity type; growing a thin insulator layer on the surface of said semiconductor substrate; depositing a first polysilicon layer; forming a first opening in said first polysilicon layer, and in said thin insulator layer, exposing a portion of the top surface of said doped region of said photodiode element; depositing a second polysilicon layer, completely filling said first opening; patterning of said second polysilicon layer, and of said first polysilicon layer, to form a polysilicon pad structure overlying a position of said thin insulator layer, contacting the region of said photodiode region, exposed in said first opening, and to form a polysilicon gate structure, on said thin insulator layer, overlying a second portion of said semiconductor substrate; forming insulator spacers on the sides of said polysilicon gate structure, and on the sides of said polysilicon pad structure, and forming a source/drain region, of a second conductivity type, in a region of said second portion of said semiconductor substrate, not covered by said polysilicon gate structure, creating a reset transistor for said image sensor cell; depositing an interlevel dielectric, (ILD), layer; forming a second opening, in said ILD layer, exposing a portion of the top surface of said polysilicon pad structure; and forming a metal structure, filling said second opening, and overlying a portion of said ILD layer.