A novel high-κ SONOS memory using TaN/Al2O3/Ta2O5/HfO2/Si structure for fast speed and long retention operation

A novel high-κ silicon-oxide-nitride-oxide-silicon (SONOS)-type memory using TaN/Al₂O₃/Ta₂O₅/HfO₂/Si (MATHS) structure is reported for the first time. Such MATHS devices can keep the advantages of our previously reported TaN/HfO₂/Ta₂O₅/HfO₂/Si device structure to obtain a better tradeoff between long retention and fast programming as compared to traditional SONOS devices. While at the same time by replacing hafnium oxide (HfO₂) with aluminum oxide (Al₂O₃) for the top blocking layer, better blocking efficiency can be achieved due to Al₂O₃´s much larger barrier height, resulting in greatly improved memory window and faster programming. The fabricated devices exhibit a fast program and erase speed, excellent ten-year retention and superior endurance up to 10⁵ stress cycles at a tunnel oxide of only 9.5 Å equivalent oxide thickness.