Hafnium tetraiodide and oxygen as precursors for atomic layer deposition of hafnium oxide thin films

Hafnium tetraiodide and oxygen were used as precursors for atomic layer deposition of hafnium dioxide (HfO2) thin films on silicon substrates at temperatures of 400-750 degreesC. At 500-750 degreesC the growth rate ranged from 0.11 to 0.12 nm/cycle and, within the experimental uncertainty, did not depend on the substrate temperature. With the decrease of the substrate temperature from 500 to 400 degreesC, however, the growth rate decreased to 0.035 nm/cycle. All films contained monoclinic HfO2. In addition, some amount of cubic, tetragonal or orthorhombic phase was observed in thinner films, particularly in those deposited at lower substrate temperatures and lower oxygen doses. The relative dielectric constant of the films measured at the frequency of 500 kHz reached 16. (C) 2002 Elsevier Science B.V. All rights reserved.