US 6,143,474 AGranted

Method of fabricating polysilicon structures with different resistance values for gate electrodes, resistors, and capacitor plates

AssigneeTaiwan Semiconductor Manufacturing Company, Ltd.

InventorsChih-Heng Shen, Sen-Fu Chen, Huan-Wen Wang, Ying-Tzu Yen

Life of this patent

Estimating the term…

Loading patent…

Abstract

This method forms structures with different resistance values from a single polysilicon film formed on a substrate. Form a hard masking layer on the polysilicon film. Form a photoresist mask over the hard masking layer. Partially etch the hard masking layer through the photoresist mask to reduce the thickness of the polysilicon while leaving the remainder of the hard masking layer with the original thickness. The thickness is reduced in locations where a low resistance is to be located in the polysilicon film. Then dope the polysilicon layer through the hard masking layer with variable doping as a function of the reduced thickness and the original thickness of the hard masking layer.

Claims19

Dependent claims

A method of forming a plurality of structures with different resistance values from a single polysilicon layer comprising:

(a) forming a polysilicon layer upon a substrate,
(b) forming a hard masking layer upon said polysilicon layer with an original thickness,
(c) masking said hard masking layer with a first mask having an opening therethrough to expose a portion of said hard masking layer which is to be partially etched away to form a reduced thickness portion of said hard masking layer,
(d) etching through said opening to etch partially through said hard masking layer to produce a reduced thickness thereof below said opening in said mask while leaving the remainder of said hard masking layer with said original thickness,
(e) removing said first mask,
subsequent of removing said first mask performing the steps as follows:
(f) patterning said polysilicon layer by the steps comprising:
(1) forming a second mask with openings through said second mask over said hard mask layer,
(2) etching away exposed portions of said hard mask layer through said openings through said second mask down to said polysilicon layer thereby providing a patterned hard mask layer and exposing portions of said polysilicon layer below said openings through said second mask,
(3) stripping away said second mask leaving said patterned hard mask layer with said portions of said polysilicon layer exposed aside from said hard mask layer,
(4) etching away exposed portions of said polysilicon layer, and
(g) subsequent to step (f) performing the step of doping said polysilicon layer through said hard masking layer with variable doping as a function of said reduced thickness and said original thickness of said hard masking layer.

9 more elements

A method of forming a plurality of structures with different resistance values from a single polysilicon layer comprising:

(a) forming a polysilicon layer upon a substrate,
(b) forming a hard masking layer upon said polysilicon layer with an original thickness,
(c) masking said hard masking layer with a first photoresist mask having an opening therethrough to expose a portion of said hard masking layer which is to be partially etched away to form a reduced thickness portion of said hard masking layer,
(d) etching through said opening in said first photoresist mask to etch partially through said hard masking layer to produce a reduced thickness thereof below said opening in said mask while leaving the remainder of said hard masking layer with said original thickness, said original thickness portion is from 0.3 .mu.m to 0.5 .mu.m thick, and said reduced thickness portion is from 0.01 .mu.m to 0.15 .mu.m thick,
(e) removing said first photoresist mask,
subsequent to removing said first mask performing the steps as follows:
(f) patterning said polysilicon layer by the steps comprising:
(1) forming a second photoresist mask with openings through said second photoresist mask over said hard mask layer,
(2) etching away exposed portions of said hard mask layer through said openings through said second photoresist mask down to said polysilicon layer thereby providing a patterned hard mask layer and exposing portions of said polysilicon layer below said openings through said second photoresist mask,
(3) stripping away said second photoresist mask leaving said patterned hard mask layer with said portions of said polysilicon layer exposed aside from said hard mask layer,
(4) etching away exposed portions of said polysilicon layer, and
(g) subsequent to step (f) performing the step of doping said polysilicon layer through said hard masking layer with variable doping as a function of said reduced thickness and said original thickness of said hard masking layer.

9 more elements

Dependencies are inferred from the claim text.