Epitaxial channel formation methods and structures

Abstract

A method for forming field effect transistors (FETs) in a multiple wafers per batch epi-reactor includes, providing substrates having therein at least one semiconductor (SC) region with a substantially flat outer surface, modifying such substantially flat outer surface to form a convex-outward curved surface, forming an epitaxial semiconductor layer on the curved surface, and incorporating the epitaxial layer in a field effect transistor formed on the substrate. Where the SC region is of silicon, the epitaxial layer can include silicon-germanium. In a preferred embodiment, the epi-layer forms part of the FET channel. Because of the convex-outward curved surface, the epi-layer grown thereon has much more uniform thickness even when formed in a high volume reactor holding as many as 100 or more substrates per batch. FETs with much more uniform properties are obtained, thereby greatly increasing the manufacturing yield and reducing the cost.