Nitrided tetragonal ZrO2 as the charge-trapping layer for nonvolatile memory application

Abstract

Employment of a tetragonal ZrO2 film as the charge-trapping layer for nonvolatile memory was investigated and the NH3 nitridation effect of the ZrO2 film on memory performance was also explored in this letter. The permittivity of the tetragonal ZrO2 film is slightly reduced from 38.7 to 36.9 after nitridation; nevertheless, nitridation introduces more trapping sites and passivates the grain boundary channel which results in a high operation speed in terms of 2.6-V flatband voltage shift by programming at +10 V for 10 ms and a good retention characteristic with 20.2% charge loss after ten-year operation at 125 °C, both are superior to that without NH3 nitridation. Most importantly, the process is fully compatible with existent ULSI technology and paves the way to adopt a high-permittivity crystalline dielectric as the charge-trapping layer for future high-performance nonvolatile memory. © 2009 IEEE.