Towards nondestructive carrier depth profiling

As indicated by the International Technology Roadmap for Semiconductors (ITRS) (http://public.itrs.net/), obtaining accurate information on the electrically active dopant profile for sub-30nm structures is a key issue. Presently, however, there is no conventional destructive (probe based) technique available satisfying the ITRS targeted depth (3%) and carrier level (5%–10%) reproducibility and accuracy. In this work, we explore the promising capabilities of a nondestructive photomodulated reflectance technique, based on the local detection of variations in the reflectivity of the sample due to thermal and plasma (excess carrier) effects as can be generated by a modulated pump laser such as in the therma-probe (TP) system. Experimental data obtained on chemical vapor deposition grown layers will be discussed with respect to junction depth and active dopant (carrier) level sensitivity. A methodology to decouple the junction depth and peak carrier concentration information for unknown samples based on the co...