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US 6,309,934 B1Granted
Fully self-aligned high speed low power MOSFET fabrication
AssigneeThe United States of America as represented by the Secretary of the Navy
InventorsMarty Peckerar, Weizhong Wang, John Melngailis
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Abstract
Channel doping and gate lithography are simulatneously performed by focusing an ion beam into the wafer through a positive or negative photoresist that is sensitive to the ion beam. Additional fabrication is then performed to provide a gate that is self-aligned with the doped channel.
Claims2
A method of forming a metal-oxide-semiconductor field effect transistor having a self-aligned gate, comprising the steps of:
- forming a substrate comprising a silicon wafer having, an SiO2 layer deposited on said silicon wafer;
- applying a positive photoresist layer onto said SiO2 layer;
- implanting ions by focused ion beam implantation into a region of said silicon wafer through said photoresist layer and said SiO2 layer, thereby forming an exposed portion of said photoresist layer directly over said region and an unexposed region of said photoresist layer;
- removing only said exposed portion of said photoresist layer to provide a substrate surface including said unexposed region of said photoresist and an uncovered portion of said SiO2 layer directly beneath said removed portion of said photoresist layer;
- depositing a gate material over said surface of said substrate so that at least a part thereof is in physical contact with said uncovered portion of said SiO2 layer;
- removing said unexposed photoresist layer and any gate material deposited over said unexposed portion of said photoresist layer;
- forming a source and a drain on said surface;
- metalizing said surface having said source and drain thereon to form metal-oxide-semiconductor device.
5 more elements
A method of forming a metal-oxide-semiconductor field effect transistor having a self-aligned gate, comprising the steps of:
- forming a substrate comprising a silicon wafer having, an SiO2 layer deposited on said silicon wafer;
- depositing a gate material over said SiO2 layer;
- applying a negative photoresist layer onto said gate material;
- implanting ions by focused ion beam implantation into a region of said silicon wafer through said photoresist layer, said gate layer, and said SiO2 layer, thereby forming an exposed portion of said photoresist layer directly over said region and an unexposed region of said photoresist layer;
- removing only said unexposed portion of said photoresist layer to provide a substrate surface including an uncovered portion of said SiO2 layer directly beneath said removed portion of said photoresist layer and a gate material, directly over said region and covered by said exposed portion of said photoresist;
- removing said exposed portion of said photoresist to uncover said gate material therebeneath;
- forming a source and a drain on said surface;
- metalizing said surface having said source and drain thereon to form metal-oxide-semiconductor device.
5 more elements
Dependencies are inferred from the claim text.