Patent ID: 6475916
Filing Date: 2002-11-05
Classification: H01L

Abstract:
A method of creating ultra-thin layers of gate oxide whereby said ultra-thin layers of gate oxide serve as gate oxide of a polysilicon gate structure, comprising the steps of:providing a semiconductor substrate wherein said semiconductor substrate comprises an active region that is laterally displaced between a pair of isolation regions; growing a layer of sacrificial gate oxide on a surface of said substrate; performing channel implant into a surface of said substrate; depositing a layer of nitride over a surface of said layer of sacrificial gate oxide; patterning and etching said layer of nitride thereby creating openings in said layer of nitride thereby furthermore exposing surface areas of said layer of gate oxide where said ultra-thin layers of gate oxide are to be created, allowing for an over-etch into the surface of the layer of sacrificial oxide, thereby partially retaining the layer of sacrificial oxide over a bottom surface of said openings; pre-cleaning said exposed surface of said layer of sacrificial gate oxide where said ultra-thin layers of gate oxide are to be created thereby creating pre-cleaned areas where said ultra-thin layers of gate oxide are to be created; performing gate oxide growth over said pre-cleaned areas thereby creating said ultra-thin layers of gate oxide; depositing a layer of polysilicon over a surface of said layer of nitride thereby including said openings in said layer of nitride said layer of polysilicon thereby overlaying said ultra-thin layers of gate oxide; removing said layer of polysilicon from a surface of said layer of nitride thereby leaving said deposited polysilicon inside said openings in said layer of nitride thereby creating poly gate structures that overly said ultra-thin layers of gate oxide; and removing said layer of nitride thereby leaving said poly gate structures in place.