Novel SONOS-type nonvolatile memory with band engineered Hf<inf>x</inf>Al<inf>y</inf>O charge trapping layer as floating gate

Abstract

As a potential candidate of next generation flash memory technology, SONOS type flash memories have many advantages over conventional flash memory devices. It is considered one of the most promising approaches to replace the highly doped polysilicon continuous floating gate technology widely used today. However, there is still big challenge in achieving low operation voltage, a fast programming/erasing speed, good retention and endurance characteristics simultaneously for further scale down. In this paper, we present a novel method of floating gate band engineering to improve the memory device performance. By manipulating the Hf:Al content ratio of Hf¿AL/O , which is used as charge trap layer in the memory cell, good programming and retention characteristics were achieved simultaneously.The fabrication of the flash memory device started with P type Si substrate (1-15 ¿'-cm).