Fabrication & electrical characterization of SiGe nanocrystal flash memory devices embedded in high k dielectrics

Abstract

Scaling of floating gate memory is now at an impasse. Engineered tunnel barriers and discrete storage nodes are not only important for scaling but also for reducing capacitive coupling with adjacent cells. To aggrandize programming efficiency and to improve retention, thick high-k materials is an alternate solution. In this research deposition of SiGe nanocrystals on SiO2 and HfO2 substrates was studied. Analysis indicated that nucleation of Ge takes place preferentially on pre-nucleated Si. Transistors with SiGe nanocrystals embedded in HfO2 were fabricated and analysed. Programming / Retention of the memory transistors were studied and different charge storage nodes were identified.