ANISOTROPIC ETCH-STOP PROPERTIES OF NITROGEN-IMPLANTED SILICON

An analysis of the anisotropic etch-stop properties of buried layers o btained by sub-stoichiometric nitrogen implantation into silicon and a nnealing has been performed as a function of the processing parameters . The aim of this work is to determine the minimum implantation dose n eeded for the formation of etch-stop layers stable under high-temperat ure thermal processing, needed in smart-sensor Si technology, using te tramethyl ammonium hydroxide (TMAH) as etchant in a way that is compat ible with CMOS. The results obtained show this value to be in the rang e (2-4) x 10(17) N cm-2 for an effective N+ implantation energy of 75 keV. After annealing, etching of the N-rich buried layer occurs throug h localized pitch discontinuities determined by the implantation and a nnealing processes.