Synthesis and electrical characterization of a MOS memory containing Si nanoparticles embedded in high-k HfO2 thin film

Abstract

The size-controlled, non-agglomerated, 5nm Si nanoparticles were fabricated in the middle of HfO2 layers using a pulsed laser ablation (PLA) system at a relatively low pressure and formed trilayer structure (HfO 2/Si-nps/HfO2) on n-type Si. These high density nanoparticles (>1x1011 cm-2) were imaged with SEM. The crystallinity of HfO2 and Si nanoparticles were characterized by HRTEM. The memory effect of a Si nanoparticles floating gate memory structure consisting of HfO2 tunneling and control oxides have been investigated by means of high-frequency (1 MHz) capacitance-voltage (C-V) measurements. HRTEM study revealed that the Si nanoparticles are single crystals with average size of about 5 nm in diameter and are well distributed within the amorphous HfO2 matrix. The memory effect was observed by the hysteresis loop in the C-V curves and a high storage charge density of about 5×1011cm-2 and a large flat-band voltage shift of 4.8V have been achieved due to charging and discharging to the nanoparticles. © 2009 IOP Publishing Ltd.