ENGINEERED BARRIERS WITH HAFNIUM OXIDE FOR NON-VOLATILE APPLICATIONS

The innovative concept of engineered barriers in the tunnel dielectric stack is very promising for low-voltage non-volatile memory applications. In this paper transport in engineered barriers using hafnium oxide (HfO2) as high-k dielectric is experimentally investigated. The structure was of the type: Al/HfO2/SiO2/Si. Experiments demonstrate that transport at program and erase voltages is limited by traps in the high-k film. Modelling with Poole-Frenkel conduction quantitatively reproduces experiments, with trap parameters derived from high temperature measurements. Respect to a film of pure SiO2 with the same EOT, real HfO2/SiO2 barriers exhibit lower leakage at low fields, thanks to the greater physical thickness, in spite of a much lower conduction at operation voltages. The effectiveness of engineered barriers fatally depends on the electronic features of the high-k dielectric.