Improvement of Ge MOS Electrical and Interfacial Characteristics by using NdAlON as Interfacial Passivation Layer

The Ge metal-oxide-semiconductor (MOS) capacitors were fabricated with HfO2 as gate dielectric. AlON, NdON, and NdAlON were deposited between the gate dielectric and the Ge substrate as the interfacial passivation layer (IPL). The electrical properties (such as capacitance-voltage (C-V) and gate leakage current density versus gate voltage (Jg-Vg)) were measured by HP4284A precision LCR meter and HP4156A semiconductor parameter analyzer. The chemical states and interfacial quality of the high-k/Ge interface were investigated by X-ray photoelectron spectroscopy (XPS). The experimental results show that the sample with the NdAlON as IPL exhibits the excellent interfacial and electrical properties. These should be attributed to an effective suppression of the Ge suboxide and HfGeOx interlayer, and an enhanced blocking role against interdiffusion of the elements during annealing by the NdAlON IPL.