Activation of implanted n-type dopants in Ge over the active concentration of 1× 10²⁰ cm^-3 using coimplantation of Sb and P

Abstract

One of the greatest challenges in fabricating a Ge-channel n-MOSFET is achieving a high n-type dopant activation within the source and drain regions. Conventional approaches to increase the electrically active doping level have been proven to be unsatisfactory, and typically the highest activation of n-type dopants is 4× 1019 cm-3 using phosphorus. This article describes a method to enhance the activation level of n-type dopants in Ge. Coimplantation of phosphorus and antimony leads to dopant activation over 1× 1020 cm-3 at 500°C. The enhancement of n-type dopant activation is attributed to reducing the implantation damage upon annealing due to increase in solid solubility of the dopants. © 2009 The Electrochemical Society.