Nanosheet transistor with uniform effective gate length
AssigneeGlobalfoundries Inc.
InventorRuilong Xie
Life of this patent
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Abstract
A method of forming nanosheet and nanowire transistors includes the formation of alternating epitaxial layers of silicon germanium (SiGe) and silicon (Si), where the germanium content within respective layers of the silicon germanium is systemically varied in order to mediate the selective etching of these layers. The germanium content can be controlled such that voids created by removal of the silicon germanium have uniform dimensions, and the backfilling of such voids with gate dielectric and gate conductor layers proximate to silicon nanosheets or nanowires results in devices having a uniform effective gate length.
Claims18
A method of fabricating a device, comprising:
- forming a stack of alternating layers of epitaxial silicon germanium and epitaxial silicon over a semiconductor substrate;
- patterning the stack of alternating layers of epitaxial silicon germanium and epitaxial silicon to form a fin;
- and
- forming a sacrificial gate structure over the fin, wherein each successive layer of silicon germanium has a germanium content that is less than that of a previously-formed layer of silicon germanium.
A method of fabricating a device, comprising:
- forming a stack of alternating layers of epitaxial silicon germanium and epitaxial silicon over a semiconductor substrate, wherein each successive layer of silicon germanium has a germanium content that is 2 to 5 atomic percent less than that of a previously-formed layer of silicon germanium;
- forming a sacrificial gate structure over the stack of alternating layers;
- forming sidewall spacers over sidewalls of the sacrificial gate structure;
- etching the stack of alternating layers using the sacrificial gate structure and the sidewall spacers as an etch mask to form a fin having tapered sidewalls;
- and
- removing the silicon germanium layers from under the sidewall spacers to form recessed regions, wherein remaining portions of the silicon germanium layers have a substantially equal width.
Dependencies are inferred from the claim text.