Structural and electrical properties of yttrium oxide with tungsten gate

A new gate-stack which consists of tungsten (W) deposited by low-pressure chemical-vapor deposition and yttrium oxide (Y2O3) deposited by RF reactive magnetron sputtering has been investigated as an alternate gate electrode/gate dielectric structure for ULSI metal-oxide-semiconductor field effect transistors (MOSFETs). The crystallinity of the yttrium oxide films was enhanced when the substrate temperature was increased during reactive sputtering. The dielectric constant of Y2O3 deposited at room temperature was higher and the leakage current was lower than those deposited at elevated temperatures. Although reactive sputtering deposition and annealing of Y2O3 led to the growth of an intermediate SiO2 layer at the Y2O3/Si interface, W/Y2O3 (∼330 )/SiO2(∼45 )/Si MIS capacitors showed a high effective dielectric constant of 14 ∼ 18 and good electrical properties