Problems with metal-oxide high-κ dielectrics due to 1/t dielectric relaxation current in amorphous materials

摘要

A potentially serious device integration problem exists with metal-oxide high-κ dielectrics such as HfO₂ and ZrO₂. The problem is that an applied voltage causes these materials to develop a residual polarization that can remain long after the voltage is removed. This phenomenon, called dielectric relaxation (DR), occurs in all amorphous insulators, although the effect is several orders of magnitude smaller in SiO₂ (and therefore practically unimportant). We present measurements of DR in HfO₂ and ZrO₂, and a theory capable of explaining these results, among others. The central point of the theory is that it is atomic, rather than electronic, currents which give rise to DR. They are due to atomic disorder and would not arise in perfect high-κ crystals.