LPCVD synthesis of silicon nanodots from silane and for flash mamory devices

Abstract

The increase of microelectronic device potentialities essentially derives from the reduction of feature size down to the nanometer scale. Multinanocrystals memories are one illustration of this trend. A multi-field study is reported, aiming to better understand phenomena involved in silicon nanocrystals elaboration. A first objective is to better control the density and the size of silicon nanocrystals formed during Low Pressure Chemical Vapor Deposition (LPCVD). Some experimental results will be presented, aiming a reliable estimation of densities and sizes of nanocrystals using several techniques: ellipsometry measurements, SEM and TEM image analysis. These experimental data have been simulated at the reactor scale using the Computational Fluid Dynamics (CFD) code FLUENT. A new kinetic scheme has been developed, which considers the various chemisorption sites existing on SiO2 substrates. This new modelling approach allows to correlate in transient mode the local composition of the gas phase near the substrate with the various sites number and with the density and the size of nanocrystals