International Business Machines Corporation
Contact source/drain resistance

Abstract:

A nonplanar MOSFET device such as a FinFET or a sacked nanosheets/nanowires FET has a substrate, one or more nonplanar channels disposed on the substrate, and a gate stack enclosing the nonplanar channels. A first source/drain (S/D) region is disposed on the substrate on a source side of the nonplanar channel and second S/D region is disposed on the substrate on a drain side of the nonplanar channel. The first and second S/D regions made of silicon-germanium (SiGe). In some embodiments, both S/D regions are p-type doped. Contact trenches provide a metallic electrical connection to the first and the second source/drain (S/D) regions. The S/D regions have two parts, a first part with a first concentration of germanium (Ge) and a second part with a second, higher Ge concentration that is a surface layer having convex shape and aligned with one of the contact trenches.