Effect of interlayer composition on passivation of (1 0 0)Si/HfO2 interface states by hydrogen

We report on a study of the influence of the particular HfO2 deposition process on the thermal passivation in molecular hydrogen of the (1 0 0)Si/HfO2 interface with the aim to minimize the interface trap density Dit. The HfO2 films, 5–10 nm thick, were grown on (1 0 0)Si by three different chemical vapour deposition (CVD) processes: atomic-layer (AL-CVD), metal-organic (MO-CVD), and nitrato CVD (N-CVD). The interface trap density Dit(E) profile for the (1 0 0)Si/HfO2 systems prior to and after passivation in H2 at 400 °C has been analysed by the G–V and C–V methods. Sets of (1 0 0)Si/HfO2 samples prepared using the three indicated CVD techniques were compared both in the as-deposited state and after post-deposition annealing (PDA) in a N2 + 5% O2 mixture. The results show that the occurring Dit is highly sensitive to the type of deposition process used and can be reduced by PDA. It is inferred that the incorporation of nitrogen in interfacial layers significantly hampers the passivation efficiency.