Dependence of optimized annealing temperature for tetragonal phase formation on the Si concentration of atomic-layer-deposited Hf-silicate film

Abstract

This study examined the relation between the permittivity and microstructures of atomic layer deposited Hf(1-x)Si(x)O(2) (HfSiO) thin films with different Si concentrations as a function of post-deposition annealing (PDA) temperature. The PDA at high temperature results in the separation of crystallized HfO(2) phase from the much higher Si-containing amorphous-like matrix. Tetragonal phase HfO(2) formation with higher permittivity than the monoclinic HfO(2) phase is induced with an appropriate Si concentration in the film (similar to 10-20%). In the crystallized HfSiO film, the Si concentration in the phase-separated HfO(2) (mainly consisting of HfO(2)) could be controlled by PDA temperature, which determines the degree of phase separation. The increased PDA temperature reduces the Si concentration in the phase-separated HfO(2), which induced monoclinic phase formation. Therefore, the PDA temperature for maximized permittivity of the crystallized HfSiO films (maximized tetragonal phase portion in the film) depends on the Si concentration of the HfSiO film in the as-deposited state. (C) 2011 American Institute of Physics. [doi:10.1063/1.3665411]