Novel SONOS and Floating-Gate Flash Memory Cell Structures for High Density and High Reliability Applications

Abstract

The flash memory technology meets physical and technical obstacles for further scaling. New structures and new materials are implemented as possible solutions. This paper focuses on two kinds of new flash cells for high density, low power and high reliability memory applications. One is the newly-proposed dual doping floating gate (DDFG) flash cell with compatible fabrication technology. The DDFG flash cell with the floating gate of lateral PNP sandwich doping profile shows higher programming speed, lower power, better data retention characteristics and comparable erasing performance in comparison with conventional n-type floating gate cells. To further enhance the storage density, VD-NORM with dual-nitride-trapping-layer and vertical structure is proposed and experimentally demonstrated for four-bit-per-cell storage capability. The novel DDFG flash cell and VD-NORM structures can be considered as potential candidates for different flash memory applications.