Hybrid Silicon Nanocrystal Silicon Nitride Dynamic Random Access Memory

This paper introduces a silicon nanocrystal-silicon nitride hybrid single transistor cell for potential dynamic RAM (DRAM) applications that stores charge in silicon nanocrystals or a silicon nitride charge trapping layer or both. The memory operates in the direct tunneling regime for the tunnel oxide and so presents the possibility of a DRAM with good cycling endurance. The silicon nanocrystals of this hybrid device present intermediate states that facilitate tunneling transport to and from the nitride layer. Short time measurements show that the hybrid silicon nanocrystal silicon nitride based DRAM cell programs and erases much faster than a plain SONOS implementation while offering better data retention, memory signal and longer refresh time than a silicon nanocrystal type DRAM.