Finfet with multilayer fins for multi-value logic (mvl) applications and method of forming

Abstract

A method of forming a multi-valued logic transistor with a small footprint and the resulting device are disclosed. Embodiments include forming plural fins on a silicon substrate, each fin covered with a hardmask; filling spaces between the fins and hard masks with an oxide; removing the hardmasks and recessing each fin, forming a cavity in the oxide over each fin; forming plural Si-based layers in each cavity with an increasing percentage of Ge or C or with an decreasing concentration of dopant from a bottom layer to a top layer; performing CMP for planarization to a top of the fins; recessing the oxide to a depth slightly below a top portion of the fin having a thickness equal to a thickness of each Si-based layer; and forming a high-k gate dielectric and a metal gate electrode over the plural Si-based layers.