Journal of Vacuum Science & Technology B, Vol.24, No.3, 1139-1146, 2006
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-30 nm 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 conventionally available TP signals will be presented. Also simulations and theoretical insights relating to the methodology will be discussed. (c) 2006 American Vacuum Society.