Fin formation by epitaxial deposition

A method of forming a fin structure for a field effect transistor, the method comprising:

• patterning a mandrel on a surface of a substrate to form columns of mandrel material, wherein the patterning comprises etching a notch into the substrate to expose a sub-surface lattice plane different than a surface lattice plane of the substrate;
• depositing an epitaxial layer of high-mobility channel material over exposed surfaces of patterned mandrel and the notch in the substrate, wherein the epitaxial layer forms on a notch surface having the sub-surface lattice plane, and wherein the epitaxial layer leaves a gap between adjacent columns of the patterned mandrel;
• planarizing the epitaxial layer to form a planarized epitaxial layer and exposing the columns of the patterned mandrel;
• and
• etching at least a portion of the exposed columns of the patterned mandrel to expose at least a portion of the planarized epitaxial layer that forms the fin structure.

A method of forming a fin structure for a field effect transistor, the method comprising:

• etching a substrate to form adjacent mandrel columns of a patterned mandrel into the substrate, wherein the adjacent mandrel columns comprise the substrate material;
• depositing an epitaxial layer of high-mobility channel material over exposed surfaces of the adjacent mandrel columns, wherein the epitaxial layer leaves a gap between the adjacent mandrel columns;
• planarizing the epitaxial layer to form a planarized epitaxial layer and exposing a surface of the adjacent mandrel columns;
• and
• etching at least a portion of the exposed adjacent mandrel columns to expose at least a portion of the planarized epitaxial layer that forms the fin structure.