Device fabrication by anisotropic wet etch
AssigneeInternational Business Machines Corporation
InventorsYujun Li, Kenneth Settlemyer, Jochen Beintner
Life of this patent
Estimating the term…
Abstract
A method of fabrication and a field effect device structure are presented that reduce source/drain capacitance and allow for device body contact. A Si based material pedestal is produced, the top surface and the sidewalls of which are oriented in a way to be substantially parallel with selected crystallographic planes of the pedestal and of a supporting member. The pedestal is wet etched with an anisotropic solution containing ammonium hydroxide. The sidewalls of the pedestal become faceted forming a segment in the pedestal with a reduced cross section. The dopant concentration in the reduced cross section segment is chosen to be sufficiently high for it to provide for electrical continuity through the pedestal.
Claims20
A method for fabricating a field effect device, comprising:
- producing a pedestal by forming a trench in a monocrystalline Si based material member, said pedestal having a top surface and a plurality of sidewalls, wherein said top surface and said plurality of sidewalls are so oriented as to be substantially parallel with crystallographic planes of said Si based material member;
- wet etching said pedestal with a solution comprising ammonium hydroxide (NH4OH), wherein due to differing etch rates of crystallographic planes in said solution said plurality of sidewalls become faceted, wherein said faceting creates a reduced cross section segment on said pedestal;
- and
- in said reduced cross section segment, selecting a dopant concentration such that said reduced cross section segment is electrically conductive, wherein allowing for electrical continuity between said field effect device and said Si based material member, wherein said field effect device is coupled to said top surface.
A device, comprising:
- a pedestal of a monocrystalline Si based material, said pedestal comprising a first segment with a top surface, a second segment beneath said first segment, and a plurality of sidewalls, wherein at least one of said plurality of sidewalls comprises at least two facets, wherein each one of said facets and said top surface are substantially parallel with crystallographic planes of said pedestal, said facets are undercutting said first segment wherein said second segment has a smaller cross section than said first segment, wherein said second segment is electrically conductive;
- a field effect device coupled to said top surface;
- a member, wherein said pedestal is situated over said member, wherein said second segment electrically connects said member and said field effect device.
Dependencies are inferred from the claim text.