Study of hafnium oxide deposited using Dense Plasma Focus machine for film structure and electrical properties as a MOS device

摘要

The electrical properties of HfO_2 gate dielectric as a MOS structure deposited using Dense Plasma Focus (DPF) device under different ambient gases were investigated. DPF is unique machine used for the first time to fabricate a MOS device as it can be used to deposit dielectric film in one shot and can also be used to change the properties of the thin film surface. The films were first deposited under pre-optimized conditions of DPF device to have best focus for producing ions. The substrate for deposition of dielectric material was placed at a distance of 5 cm from the focus under argon ambient and then under nitrogen ambient. The I-V, C-V characteristics of the dielectric film were investigated employing AI-HfO_2-Si MOS capacitor structure deposited using DPF. The MOS devices were studied to determine electrical parameters like breakdown voltage, oxide charges and leakage current deposited under two different gas ambient. The microstructure of thin film is examined by using AFM and the thickness of the film is examined using an ellipsometer. The reduction in surface roughness, shift in Flat-band voltage (V_(fb)) and reduction in oxide-charge density (Q_(ox)) is seen maximum for MOS capacitor where HfO_2 as gate dielectric is deposited under nitrogen ambient using DPF machine.