In this article, we report the effect of fixed oxide charge in Al2O3 blocking dielectric on memory properties of charge trap flash memory devices using Fowler-Nordheim program/erase mode. It was found that negative fixed oxide charges in the Al2O3 dielectric play a crucial role in improving erase efficiency of Al2O3/SiN/SiO2 (ANO) stacks, and thus reinforces the advantages of a Al2O3 blocking layer for charge trap flash devices. Compared to n(+)poly-Si/ONO stack, process-optimized ANO stack with high work-function metal gate shows dramatic improvements in retention vs minimum erase state. (c) 2006 The Electrochemical Society.