Patent ID: 6440782
Filing Date: 2002-08-27
Classification: H01L

Abstract:
A method of fabricating a silicon-based radiation-hard cryogenic complementary metal oxide semiconductor (cryo-CMOS) charge-coupled device (CCD), said method comprising sequential steps of:providing a silicon substrate; forming in a CMOS active device area a pair of adjacent wells of opposite doping type in said substrate, and an adjacent CCD area; providing a layer of re-oxidized nitride/oxide over said CCD area and said CMOS active device area; providing a layer of polysilicon over said layer of re-oxidized nitride/oxide, over said pair of adjacent wells and said adjacent CCD area; plasma etching said layer of polysilicon at said pair of wells to define a respective pair of gates for transistors to be formed in said pair of wells; and simultaneously protecting said layer of polysilicon and re-oxidized nitride/oxide over said CCD area so that both are substantially not affected by said plasma etching; wet-chemical etching said layer of polysilicon over said CCD area to form first polysilicon gates for said CCD area, while substantially not attacking said re-oxidized nitride/oxide layer at said CCD area with said wet-chemical etch.