Technology options for reducing contact resistances in nanoscale metal-oxide-semiconductor field-effect transistors

Technology options for reducing contact resistances in advanced transistors will be discussed. With scaling down of the size of metal-oxide-semiconductor field-effect transistors (MOSFETs) and with channel strain engineering to increase carrier mobility or reduce channel resistance, the external series resistance R_ext has become a more significant component of the total resistance between the source and the drain regions. An important component of R_ext is the contact resistance R_C between contact metallization and the heavily doped source or drain (S/D) region. Solutions for reducing R_C or the Schottky barrier height between the contact metal and the S/D regions will be reviewed.