Scaling evaluation of BE-SONOS NAND flash beyond 20 nm

We have successfully fabricated and characterized sub-30 nm and sub-20 nm BE-SONOS NAND Flash. Good device characteristics are achieved through two innovative processes: (1) a low-energy tilt-angle STI pocket implantation to suppress the STI corner edge effect, and (2) a drain offset using an additional oxide liner to improve the short-channel effect. The conventional self-boosting program-inhibit and ISPP (incremental step pulse programming) for MLC storage are demonstrated for 20nm BE-SONOS NAND operation. Read current stability and read disturb life time are also evaluated. The estimated number of storage electrons is only 50–100, and for the first time we have demonstrated successful data retention after 150°C baking in the “few-electron” regime. Our results strongly suggest that BE-SONOS is a promising charge-trapping (CT) technology for NAND Flash scaling.