Impact of Work Function Optimized S/D Silicide Contact for High Current Drivability CMOS

Abstract

A formation process of the silicide/Si contact with low contact resistance in the source/drain (S/D) regions has been developed in order to reduce the S/D electrodes series resistance of MOSFETs. Er that has a low Schottky barrier height (SBH) for electrons and Pd that has a low SBH for holes were selected to n+- and p+-Si, respectively. The silicide formation process were carried out in N2 ambient from the Si surface cleaning before the metal depositions to the silicidation anneal in order not to expose metal and Si region so as to prevent the oxidation. W capping layer was formed on the Er surface for preventing Er from being oxidized, because the work function of Er is very low and it is very easily oxidized. These silicides were applied to Metal-Oxide-Semiconductor Field Effect Transistors (MOSFETs), the improvement of the current drivability of n- and p-MOSFET was realized due to the reduction of the S/D electrodes series resistance.