Fabrication and Evaluation of Floating Gate Memories with Surface-Nitrided Si Nanocrystals

Abstract

A floating-gate memory with surface-nitrided Si nanocrystals buried in a SiO2 matrix has been fabricated employing radical nitridation. Si nanocrystals with a number density higher than 1×1012 cm-2 and an average grain size smaller than 6 nm have been grown using an ultrathin amorphous Si layer predeposited on the SiO2 surface. Since the radical nitridation of the formed Si nanocrystals effectively suppresses excess oxidation of nanocrystals during the control oxide formation, the Si nanocrystals have been successfully buried in the SiO2 matrix without losing their number density, grain size and fine spherical shape. Electrical properties of the floating-gate memory were also examined. A flat band voltage shift larger than 1 V, which is consistent with the number density of Si nanocrystals, was observed in capacitance–voltage measurements.