SONOS-Type Flash Memory with HfO_2 Thinner than 4 nm as Trapping Layer Using Atomic Layer Deposition

摘要

A HfO_2 as the charge-storage layer with the physical thickness thinner than 4 nm in silicon-oxide-high-k oxide-oxide-silicon (SOHOS) flash memory was investigated. Compared to the conventional silicon-oxide-nitride-oxide-silicon (SONOS) flash memory, the SOHOS shows the slow operational speed and exhibits the poorer retention characteristics. These are attributed to the thin physical thickness below 4 nm and the crystallization of the HfO_2 to contribute the lateral migration of the trapped charge in the trapping layer during high temperature annealing process.