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 Si1-xGex alloy film, the interfacial and electrical characteristics of atomic-layer-deposited HfO2/Si1-xGex were studied while varying the Ge concentration (x value) from 0 to 0.3. H2S pre-annealing was performed on the Si1-xGex substrates at 400 degrees C for 30 s using a rapid thermal annealing system prior to the HfO2 deposition. As the Ge concentration in Si1-xGex 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/Si1-xGex 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.