Patent ID: 6306678
Filing Date: 2001-10-23
Classification: H01L

Abstract:
A method of forming an image sensor cell, on a semiconductor substrate, in which a photodiode element, is protected from all ion implantation procedures other than the ion implantation procedure used to form said photodiode element, and protected from a procedure used to define insulator spacers on the sides of a reset transistor, gate structure, comprising the steps of:forming a gate structure, for a reset transistor structure, on an underlying gate insulator layer, on a first portion of said semiconductor substrate, of a first conductivity type;forming a lightly doped source/drain region, of a second conductivity type, in an area of said first portion of said semiconductor substrate, not covered by said gate structure;forming a top segment of said photodiode element, of a second conductivity type, in a second portion of said semiconductor substrate;depositing a first insulator layer;forming a photoresist shape on a portion of said first insulator layer overlying said top segment of said photodiode element, leaving regions of said first insulator layer, overlying said gate structure, and overlying said lightly doped source/drain regions unprotected;performing an anisotropic, reactive ion etching procedure, to from insulator spacers, on the sides of said gate structure, and forming a first insulator shape, on said top segment of said photodiode element, underlying photoresist shape;forming a heavily doped source/drain region, of a second conductivity type, in an area of said first portion of said semiconductor substrate, not covered by said gate structure, and not covered by said insulator spacers;depositing a second insulator layer;opening a contact hole in said second insulator layer, and in said first insulator shape, exposing a portion of the top surface of said top element of said photodiode element; andforming a metal structure, in said contact hole.