A new ultra low voltage silicon-rich-oxide (SRO) NAND cell

Thin silicon-rich-oxide (SRO) film can be an efficient and reliable tunneling injector for the low voltage application in Flash memory cell. To date, no work has been done on the quantitative and microscopical tunneling model for the SRO enhancement behavior. Moreover, no complete investigation on array-level SRO Flash cell have been presented. In this paper, a new low voltage SNAND (SRO NAND) cell is proposed and investigated, especially in term of performance characteristics and reliability issues. Furthermore, a two-dimensional microscopical model for SRO tunneling characteristics is developed to quantitatively explain the tunneling enhancement characteristics for SRO Flash memory cell. Results show that the tunneling model agrees well with the tunneling characteristics of SNAND cell and also provided the insight into tunnel oxide scaling in SNAND cell operation. The erase and program voltage can be reduced from 22 V to 7 V and 12 V with improved erase speed up to 2 orders, respectively. More than 10 5 endurance cycles are achieved. The feasibility of the SNAND cell is demonstrated.