Experimental Study of 1/f1+α Noise in Transient Leakage Current of Metal–Insulator–Metal With Stacked High-k Polycrystalline Films

We have observed and analyzed the 1/f
^1+α
noise in transient leakage current through a metal-insulator-metal stacked high-k capacitor of TiN-ZrO
₂
-TiO
₂
-TiN. The ZrO
₂
and TiO
₂
films, formed by atomic layer deposition, are polycrystalline and show geometrical variety at interfaces (i.e., grain boundaries). Two types of transient leakage current are observed: 1) the monotonically decreasing component with power law dependence and 2) the uneven component having power law dependence. To analyze the uneven component in time domain, we assumed that the power law decay occurs due to a gradual change in the redistribution of electrons between interfaces of ZrO
₂
-TiN and ZrO
₂
-TiO
₂
. The frequency-domain analysis shows that the 1/f
^1+α
noise comes from the transient leakage of direct tunneling and trap-assisted tunneling (α > 0). In particular, the noise in the uneven component, the random telegraph noise part (α ~ 1), relates to local trap states in a grain boundary affected by phonon scattering. In addition, the analytical method we developed in this article shows an excellent agreement with various measurements of the transient gate leakage current.