Laterally ordered 2-D arrays of Si and Ge nanocrystals within SiO<SUB align=right>2 thin layers for application in non-volatile memories

Abstract

Silicon and germanuim nanocrystal memories show important advantages over conventional floating gate non-volatile memories. To fully exploit these advantages, it is essential to achieve accurate control of nanocrystal size and arial density, as well as accurate positioning of the nanocrystal layer within the gate dielectric. In this paper, a review of work performed at IMEL on the fabrication and characterisation of nanocrystal memory structures, using low pressure chemical vapor deposition (LPCVD) of amorphous Si followed by high temperature thermal oxidation and annealing, will be presented. Results on structures with doubly-stacked Si dots for better memory retention will be shown and discussed. Ge nanodot memory structures by electron gun evaporation will also be presented. Recent advances towards ordering and controlled positioning of Si and Ge nanocrystals in a 2-D layer within SiO2 is another part of this paper. Nanopatterning technologies for silica nanostructuring by focused ion beam milling and porous alumina-on-Si masking template technology will be discussed.