Effect of H2S pre-annealing treatment on interfacial and electrical properties of HfO2/Si1−xGex (x = 0–0.3)

Abstract

To understand the effect of H₂S pre-annealing treatment on a Si_1−xGe_x alloy film, the interfacial and electrical characteristics of atomic-layer-deposited HfO₂/Si_1−xGe_x were studied while varying the Ge concentration (x value) from 0 to 0.3. H₂S pre-annealing was performed on the Si_1−xGe_x substrates at 400 °C for 30 s using a rapid thermal annealing system prior to the HfO₂ deposition. As the Ge concentration in Si_1−xGe_x increased, the H₂S pretreatment caused a greater increase in the capacitance-equivalent oxide thickness because of accelerated interfacial oxidation by a thermal annealing side effect. However, it was advantageous in reducing the interface state density on a Ge-rich surface, which suggested effective sulfur passivation on the Ge dangling bonds at the HfO₂/Si_1−xGe_x interface. Furthermore, the H₂S pretreatment was effective in suppressing the out-diffusion of Ge towards the HfO₂ film, which was beneficial in improving the near-interface charge trapping characteristics.