High-pressure deuterium annealing for improving the reliability characteristics of silicon–oxide–nitride–oxide–silicon nonvolatile memory devices

We report the effects of high-pressure deuterium postmetallization annealing on the reliability characteristics of silicon–oxide–nitride–oxide–silicon nonvolatile memory devices. Compared with the control samples annealed in a conventional forming gas ambient (H₂/N₂=4% / 96%), the samples annealed in a high-pressure (10 atm) pure deuterium ambient show improved endurance and retention characteristics without the degradation of program/erase (P/E) speed. In addition, the high-pressure deuterium-annealed samples show a significantly reduced charge loss rate for the electron-stored state and the hole-stored state, before and after the P/E cycles. The improved reliability of the high-pressure deuterium-annealed samples can be explained by the significantly decreased interface trap density and the large kinetic isotope effect of deuterium, which reduces the generation of the interface trap density under the stress of the P/E cycles.