Formation of Ge Nanocrystals in High-k Dielectric Layers for Memory Applications

Abstract

AbstractIn this paper, the fabrication of Ge-NCs embedded in Al2O3 and HfO2 layers by ion-beam-synthesis for memory applications is investigated. Structural properties of the high-k layers before and after implantation and annealing were studied by TEM observation and EELs analysis. Spherical Ge-NCs 5nm in diameter were observed in Al2O3 implanted layers after furnace annealing at 800°C in nitrogen. Annealing studies in the range 700-1050°C in nitrogen revealed the evolution of the charge storage properties of these structures utilizing MIS capacitors test structures. No NCs were observed in HfO2 implanted layers. However, significant negative-differential-resistance regions were observed in I-V characteristics of the related MIS structures. These may be attributed to the formation of conductive paths made of hafnium germanide (HfGe2) or hafnium germanate (HfGeO) regions.