Exact control of junction position using epitaxial NiSi2 crystallization in ultrathin silicon-on-insulator metal-oxide-semiconductor field-effect transistors

Abstract

This paper reports the demonstration of exact control of the junction position in ultrathin silicon-on-insulator (SOI) metal-oxide-semiconductor field-effect transistors (MOSFETs) using epitaxial NiSi2 crystallization. In the ultrathin SOI (100) plane, NiSi2 first grows in the <100> vertical direction and along the SOI/buried oxide (BOX) interface. Subsequently, NiSi2 grows in the <110> lateral direction and sustains a (111) facet. We found that epitaxial NiSi2 crystallization in ultrathin SOI proceeds first vertically, then laterally, in a step-by-step crystallization pattern. Epitaxial NiSi2 crystallization rates for the (100) and (111) planes are proportional to the root square of the annealing time associated with the lattice diffusion reaction. Thus, the junction position in an ultrathin SOI MOSFET with metal source/drain can be exactly controlled by annealing times.