Design Considerations in Scaled SONOS Nonvolatile Memory Devices

Scaling the programming voltage, while still maintaining 10-year data retention time, has been always a big challenge for Poly-Oxide-Nitride-Oxide-Silicon (SONOS) researchers. We describe our progress in the design and scaling of SONOS nonvolatile memory devices. -9 V +10 V (1 ms) programmable SONOS devices ensuring 10 years retention time after 10(exp 7) Erase/Write cycles at 85 C have been developed successfully. Deuterium anneal, applied in SONOS device fabrication for the first time, improves the endurance characteristics better than traditional hydrogen or forming gas anneal. In this paper, we describe scaling considerations and process optimization along with experiments and characterization results.