Dopant Redistribution Effect on Post-Junction Silicide Scheme Shallow Junction and a Proposal of Novel Self-Aligned Silicide Scheme

It is concluded that in a shallow junction of post-junction silicide (PJS) scheme self-aligned silicide (SALICIDE) process, the decrease of impurity concentration at the TiSi2/Si interface significantly degrades performance of metal oxide semiconductor field effect transistor (MOSFET). It is verified for the first time that this degradation is due to dopant redistribution from Si to TiSi2 during post-silicidation annealing. Dopant redistribution is strongly confirmed by evaluation of the contact resistance at the TiSi2/Si interface and analysis of impurity concentration by improved secondary ion mass spectroscopy (SIMS) technique and a two-dimensional process simulation dealing with a SALICIDE process. In order to overcome the dopant redistribution-induced degradation, a novel SALICIDE scheme, doubly source/drain-ion-implanted SALICIDE (DIS), is proposed and concluded to be an alternative to PJS scheme.