Low-Frequency Noise Performance of HfO2-Based Gate Stacks

Abstract

The low-frequency noise characteristics of -based dielectrics have been investigated. Attention is given to the deposition technique (metal oxide chemical vapor deposition or atomic layer deposition) used, the film thickness, and the use of a interface layer. n-Type metal oxide semiconductor devices with equivalent oxide thicknesses (EOTs) of 1.5, 2, 3, and 5.5 nm were studied. It is shown that the LF noise of such high- transistors is like. The behavior of the normalized current spectral density vs the drain current points out that for relative thin interfacial layers and at high gate voltages carrier trapping in the layer governs the current fluctuations. The trap densities extracted from the noise are up to 200 times higher than in a thermal oxide reference wafer (5.5 nm EOT). The deposition technique has no strong impact on the density of traps in the high- layer, which is in the range of . However, a strong difference was observed in the noise contribution, which is dominated by carrier scattering at charged traps. For , the scattering coefficient derived from the noise is smaller than for , which can be interpreted in terms of the suppression of the coulomb scattering by the high dielectric constant.