Improved Charge-Trapping Nonvolatile Memory with Dy-doped HfO_2 as Charge-Trapping Layer and Al_2O_3 as Blocking Layer

摘要

We have investigated a charge-trapping nonvolatile memory (NVM) device with high-k dielectrics as a charge-trapping layer (HfO_2 and Dy-doped HfO_2) and a blocking layer (Al_2O_3). Compared with a conventional SiO_2/Si_3N_4/SiO_2 stack, both SiO_2/HfO_2/Al_2O_3 and SiO_2/Dy-doped HfO_2/Al_2O_3 stacks show significantly improved program and erase (P/E) speed The improvement in P/E speed characteristics can be explained by the larger band offset of HfO_2 and the increased thickness of the blocking oxide, which are the main advantages of high-k materials. Moreover, for a SiO_2/Dy-doped HfO_2/Al_2O_3 stack with an optimum Dy concentration, the enhanced retention characteristics were observed at a measurement temperature below 150℃ due to the deep energy level of the charge trap.