Ion implantation combined with in situ or ex situ heat treatment for improved field effect transistors

Abstract

This invention teaches methods of combining ion implantation steps with in situ or ex situ heat treatments to avoid and/or minimize implant-induced amorphization (a potential problem for source/drain (S/D) regions in FETs in ultrathin silicon on insulator layers) and implant-induced plastic relaxation of strained S/D regions (a potential problem for strained channel FETs in which the channel strain is provided by embedded S/D regions lattice mismatched with an underlying substrate layer). In a first embodiment, ion implantation is combined with in situ heat treatment by performing the ion implantation at elevated temperature. In a second embodiment, ion implantation is combined with ex situ heat treatments in a 'divided-dose-anneal-in-between' (DDAB) scheme that avoids the need for tooling capable of performing hot implants.