Effect of Annealing on the Interfacial and Structural Properties of Amorphous Silicon-Hafnia Films

Chemical and physical properties of the interface formed between amorphous silicon ( a -Si) and hafnium oxide (HfO 2 ) were investigated using X-ray reflectivity (XRR) and X-ray photoelectron spectroscopy (XPS). XRR showed that the interface layer formed between the a -Si and HfO 2 layer had a thickness of 0.7 ± 0.3 nm and a density of 4.4 ± 0.2 g/cm 3 . Based on the XPS results, the interface comprised HfO 2 , silicon oxide, and hafnium silicate phases. High-temperature annealing led to the conversion of elemental silicon and nonstoichiometric silicate into silicon dioxide phases. This reaction was also accompanied by the chemical reduction of the HfO 2 phase. Annealed films crystallized into the monoclinic phase of HfO 2 with a preferred orientation along the (111) axis.