Advanced contact engineering for silicon, germanium and germanium-tin devices

Abstract

This thesis involves the development of new contact engineering techniques for future generation of transistors. According to the International Technology Roadmap for Semiconductors (ITRS) 2013, silicon (Si) will remain the main semiconductor channel material of MOSFET for the foreseeable future. For sub-10 nm nodes, new materials with high bulk carriers mobilities [e.g. germanium (Ge) and germanium-tin (GeSn)] are needed to replace silicon as an alternate channel material to increase the saturation velocity. For metal/semiconductor contact formation, low contact resistance is needed, which is dependent exponentially on Schottky barrier height at the metal/semiconductor interface. In this thesis, through ion-implantation and segregation of impurity elements at the metal/semiconductor interface, modulation of Schottky barrier height has been developed for Si, Ge, and GeSn contacts. New low temperature pre-amorphization implantation (PAI) and high temperature implantation are developed. The mechanism responsible for the reduction of electron Schottky barrier height is also studied through simulation.