Interfacial reaction induced strain relaxation in Hf-silicate film on strained Si0.7Ge0.3 (001) as a function of annealing temperature



Hf-based dielectrics were prepared using atomic layer deposition in order to investigate the effect of Si incorporation on the interfacial reaction and thermal stability in HfO2 films on SiGe substrates. Two concentrations [100% HfO2 and 50% HfO2 50% SiO2(HfSiO)] were used on strained Si0.7Ge0.3 substrates; a partially-crystalline phase was observed in the as-grown HfO2 film, and was not observed in the as-grown HfSiO film. Phase separation between the SiOx and HfOx in HfSiO film did occur, however, when the annealing temperature was increased to over 900 °C, leading to the out-diffusion of Si from the Si0.7Ge0.3 substrate and the formation of a Ge-rich layer at the interface between HfSiO and Si0.7Ge0.3. Finally, the strain in the Si0.7Ge0.3 substrate was relaxed, and interfacial states greatly increased in HfSiO/Si0.7Ge0.3 with the 900 °C anneal.