Non-uniform gate dielectric for u-shape mosfet
AssigneeInternational Business Machines Corporation
InventorsPranita Kerber, Effendi Leobandung, Philip J. Oldiges
Life of this patent
Estimating the term…
Abstract
A U-shaped gate dielectric structure is provided that has a horizontal gate dielectric portion having a vertical thickness, and a vertical gate dielectric wall portion extending upwards from the horizontal gate dielectric portion. The vertical gate dielectric wall portion has a lateral thickness that is greater than the vertical thickness of the horizontal gate dielectric portion. The U-shaped gate dielectric structure houses a gate conductor portion. Collectively, the U-shaped gate dielectric structure and the gate conductor portion provide a functional gate structure that has reduced capacitance.
Claims18
A method of forming a semiconductor structure, said method comprising:
- forming a gate material stack on a semiconductor material portion, said gate material stack comprising, from bottom to top, a horizontal gate dielectric portion and a gate conductor portion, wherein said horizontal gate dielectric portion has a vertical thickness;
- forming a vertical gate dielectric wall portion surrounding sidewalls of said gate material stack and extending upwards from said horizontal gate dielectric portion, said vertical gate dielectric wall portion having a lateral thickness that is greater than said vertical thickness of said horizontal gate dielectric portion;
- and
- forming a source-side semiconductor material on one side of said gate material stack and a drain-side semiconductor material on another side of said gate material side, wherein a sidewall edge of each of said source-side semiconductor material and said drain-side semiconductor material contacts an outer sidewall of said vertical gate dielectric wall portion.
A method of forming a semiconductor structure, said method comprising:
- forming a sacrificial gate structure on a semiconductor material portion;
- forming a source region on one side of said sacrificial gate structure and on a surface of said semiconductor material portion, and a drain region on another side of said sacrificial gate structure and another surface of said semiconductor material portion;
- diffusing dopants from said source region into said semiconductor material portion to provide a source diffusion region, and dopants from said drain region into said semiconductor material to provide a drain diffusion region;
- forming a dielectric material on said source region and said drain region, said dielectric material having a topmost surface that is coplanar with a topmost surface of said functional gate structure;
- forming a gate cavity by removing said functional gate structure;
- providing a recessed channel region at a bottom of said gate cavity by etching an exposed portion of said semiconductor material portion;
- forming outer vertical gate dielectric wall segment along each sidewall of said gate cavity and said recessed channel region;
- forming a gate dielectric material having a vertical wall segment extending from a horizontal portion, wherein said horizontal portion contacts a remaining surface of said semiconductor material portion in said recessed channel region;
- and
- forming a gate conductor material in a remaining volume of said gate cavity and said recessed channel region and contacting said horizontal portion and said vertical wall segment of said gate dielectric material, wherein a combined lateral thickness of said outer vertical gate dielectric wall segment and said vertical wall segment of said gate dielectric material is greater than a vertical thickness of said horizontal portion of said gate dielectric material
Dependencies are inferred from the claim text.