Characteristics of Atomic-Layer-Deposited Al[sub 2]O[sub 3] High-k Dielectric Films Grown on Ge Substrates

This paper describes the structural and electrical properties of thin films grown through atomic layer deposition onto Ge substrates over a wide deposition temperature range . From grazing-incidence X-ray reflectivity and X-ray photoelectron spectroscopy, we found that increasing the deposition temperature improved the film density and its dielectric stoichiometry; nevertheless, dielectric intermixing between main and interfacial appeared at temperatures above , along with degradation of the interface. Accordingly, a relatively large gate leakage current and a high density of interfacial states were observed as a result of deterioration of the entire structure at higher deposition temperatures. In addition, although subsequent high-temperature processing at in a ambient could relieve the oxygen-excessive behavior further, i.e., to provide a more stoichiometric film, the accompanying volatilization close to the dielectric interface caused greater damage to the electrical performance. Only forming gas annealing ( , 1:10) at low temperature improved the capacitance–voltage characteristics of the structure, in terms of providing a lower value of (ca. ), a lower value of , and a reduced hysteresis width.