Work Function Adjustment by Using Dipole Engineering for TaN-Al₂O₃-Si₃N₄-HfSiO_x-Silicon Nonvolatile Memory

This paper presents a novel TaN-Al₂O₃-HfSiO_x-SiO₂-silicon (TAHOS) nonvolatile memory (NVM) design with dipole engineering at the HfSiO_x/SiO₂ interface. The threshold voltage shift achieved by using dipole engineering could enable work function adjustment for NVM devices. The dipole layer at the tunnel oxide-charge storage layer interface increases the programming speed and provides satisfactory retention. This NVM device has a high program/erase (P/E) speed; a 2-V memory window can be achieved by applying 16 V for 10 μs. Regarding high-temperature retention characteristics, 62% of the initial memory window was maintained after 10³ P/E-cycle stress in a 10-year simulation. This paper discusses the performance improvement enabled by using dipole layer engineering in the TAHOS NVM.