Nitrogen-concentration modulated interface quality, band alignment and electrical properties of HfTiON/Ge gate stack pretreated by trimethylaluminum precursor

Abstract

Effects of nitrogen incorporation on the interface chemical bonding states, band alignment and electrical properties of sputtering-derived HfTiO high-k gate stacks on Ge substrates pretreated by trimethylaluminum (TMA) precursor have been investigated by X-ray photoemission spectroscopy (XPS), UV–vis transmission spectroscopy, and electrical measurements. XPS results indicate that incorporation of a moderate amount of nitrogen (3sccm) incorporation can effectively suppress the formation of unstable GeO2 and low-k germinate at the interfacial region. Meanwhile, reduction in band gap and valence band offset and increase in conduction band offset have been observed after nitrogen incorporation. Electrical properties were evaluated by capacitance-voltage (C–V) and leakage current density-voltage (J–V) measurements based on MOS capacitors. Small gate leakage current (4.13×10−7A/cm2 at Vg=1V), almost disappeared hysteresis, and large dielectric constant (19.6) that have been observed for MOS capacitor with HfTiON/Ge stacked gate dielectric with N2 flow of 3sccm.