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US 8,299,573 B2Granted
Trench capacitor
AssigneeInternational Business Machines Corporation
InventorsChengwen Pei, Xi Li, Geng Wang
Life of this patent
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Abstract
A trench and method of fabrication is disclosed. The trench shape is cylindrosymmetric, and is created by forming a dopant profile that is monotonically increasing in dopant concentration level as a function of depth into the substrate. A dopant sensitive etch is then performed, resulting in a trench shape providing increased surface area, yet having relatively smooth trench walls.
Claims20
A trench capacitor comprising:
- a trench formed in a semiconductor substrate, wherein the semiconductor susbtrate comprises a monotonically increasing dopant profile that comprises a dopant concentration that is lowest at a top region of the semiconductor susbtrate and wherein the dopant concentration is highest at a bottom region of the semiconductor substrate, wherein the trench is substantially cylindrical.
A method of forming a trench capacitor in a semiconductor substrate, comprising:
- forming a dopant profile that is monotonically increasing in dopant concentration level as a function of depth into the substrate;
- and
- performing a dopant sensitive etch, such that a cylindrosymmetric trench shape is formed.
A method of forming a trench capacitor in a semiconductor substrate, comprising:
- forming a dopant profile that is monotonically increasing in dopant concentration level as a function of depth into the substrate by performing in situ doping of an epitaxial layer;
- and
- performing a dopant sensitive etch, via a reactive ion etch process, and etching a cylindrosymmetric trench, the trench having a depth ranging from about 1 micrometer to about 8 micrometers.
Dependencies are inferred from the claim text.