Oxygen diffusion barrier on interfacial layer formed with remote NH3 plasma treatment

An oxidation or nitridation treatment was performed on the interfacial layer (IL) with optimal oxidation state in order to form an oxygen diffusion barrier for Ge nMOSFET. Through the analysis of X-ray photoelectron spectroscopy and electrical characterization of Ge nMOSFET, the reaction mechanism and physical model were studied in details. The fewer interface traps and lower subthreshold swing can be achieved by forming oxygen diffusion barrier in an optimal IL with remote NH3 plasma. As compared to devices with oxidation treatments, that improvement can be attributed to the nitrogen passivation and alloy-like interface formation. The proposed oxygen diffusion barrier with remote NH3 plasma treatment on IL is a promising technique to improve the interface properties effectively without influencing equivalent oxide thickness for high performance Ge nMOSFET. •An interfacial layer buffer formation method is proposed.•An oxygen diffusion barrier can be formed by remote plasma treatment.•A n-channel Ge transistor can be enhanced by NH3 plasma.•Reaction mechanism about oxygen diffusion is explained by material analysis.