Understanding the impact of metal gate on TANOS performance and retention

Abstract

In TANOS memory, deeper erase is pursued by implementing a high work function (p-type) metal gate. Our experiments show that the metal gate may also change program and retention in a way that cannot be explained by simple electrostatic considerations. Instead, we suggest that some metal gates may give rise to a change in the properties of the underlying blocking dielectric or the interface with the nitride, leading to the abovementioned observations. Hydrogen appears to be involved in this process.