Effect of germanium concentration and tunnel oxide thickness on nanocrystal formation and charge storage/retention characteristics of a trilayer memory structure

Abstract

The effect of rapid thermal oxide (RTO) layer thickness and germanium concentration on the nanocrystal formation and charge storage/retention capabilities of a trilayer memory structure was discussed. The results showed that the RTO and the capping oxide layers were not totally effective in confining the Ge nanocrystals in the middle layer when a pure Ge middle layer was used for the formation of nanocrystals. A diffusion of Ge atoms through the RTO and into the silicon substrate was observed with the help of transmission electron microscopy and secondary ion mass spectroscopy, when the RTO layer thickness was reduced to 2.5 nm.