Finfet device with wrapped-around epitaxial structure and manufacturing method thereof

Abstract

A method includes providing a device structure having a substrate, an isolation structure over the substrate, and two fins extending from the substrate and through the isolation structure, each fin having two source/drain (S/D) regions and a channel region; depositing a first dielectric layer over top and sidewall surfaces of the fins and over the isolation structure; forming a gate stack over the first dielectric layer and engaging each fin at the respective channel region; treating surfaces of the gate stack and the first dielectric layer such that the surfaces of the gate stack are more attachable to a second dielectric layer than the surfaces of the first dielectric layer are; after the treating of the surfaces, depositing the second dielectric layer; and etching the first dielectric layer to expose the S/D regions of the fins.