Nonvolatile memories using deep traps formed in Al_2O_3 by metal ion implantation

摘要

We demonstrate the feasibility of an approach to nonvolatile memory (NVM) that exploits charge trapping at deep-energy levels formed in Al_2O_3 by metal doping. Our calculations show that V and Nb are expected to form such deep energy levels in the band gap of Al_2O_3. To demonstrate the effectiveness of this approach these metal ions were ion-implanted into test structures based on an Al_2O_3 trapping layer. Several structural analysis techniques and photocurrent spectroscopy show that the doped metal ions are located close to the Al_2O_3/SiO_2 interface and exhibit characteristics consistent with some of the deep levels predicted in calculations. The resulting test devices are shown to exhibit promising NVM characteristics.