Patent ID: 6162584
Filing Date: 2000-12-19
Classification: G03F,H01L

Abstract:
A method of forming a plurality of structures with different resistance values in a single photoresist film comprising the sequence of steps as follows:first forming an undoped planar polysilicon layer upon a planar substrate (21),then forming a first patterned mask upon said undoped polysilicon layer to expose a first portion thereof (22),then partially etching through said first portion of said planar polysilicon layer to produce a reduced thickness portion thereof while leaving the remainder as a full thickness portion of said polysilicon with said original thickness (23) below said first patterned mask,then with said first patterned mask (25) in place performing the step of doping said polysilicon layer with variable doping as a function of said reduced thickness and said original thickness of said polysilicon forming a thick, high resistance region (PSH) below said first patterned mask and a thin, low resistance region (PSL) in said polysilicon layer (24),then removing said first patteried mask (25),then forming a second patterned mask over said polysilicon layer for patterning said thick, high resistance polysilicon region and for patterning said thin, low resistance polysilicon region (26), andthen etching said polysilicon layer through said patterning mask down to said substrate producing a thick, high resistance, polysilicon element from said thick, high resistance region and producing a separate, thin, low resistance polysilicon element from said thin, low resistance region (26).