Impact of varying wet oxidation temperature in the presence of nitrogen flow on hafnium tantalum oxide films

Wet oxidation has been undergone at dissimilar temperatures from 400 until 1000 °C for deposition of high dielectric constant ternary hafnium tantalum oxide films on silicon (Si) substrates. Amorphous to polycrystalline phase transformation happened as a function of temperature. An increase in the oxygen vacancy formation was observed and the calculated k values ranged from 16.5 to 31.1. However, interfacial layer formation happened exaggeratedly at 1000 °C, which could be associated with the reduction in nitrogen accumulation at the interface between the oxide and Si at this temperature, and thus resulting in the lowest total interface trap density (Dtotal). Conductance-voltage measurement showed the location of interface states that were closer to conduction band of the oxide. The findings were in coordination with structural, morphological, and optical characteristics of the samples. A simple mechanism illustrating formation of the ternary film was also proposed.