Scaling behavior and structure transition of ZrO2 films deposited by RF magnetron sputtering

ZrO2 thin films were deposited onto Si wafers and glass slides by reactive rf magnetron sputtering with varying conditions of substrate temperature (Ts). Structural analysis was carried out using high-resolution transmission electron microscopy (HRTEM) and atomic force microscopy (AFM). The scaling behavior of the AFM topographical profiles was analyzed using one-dimensional power spectral density method (1DPSD). Morphological and structural evolution of ZrO2 films have been studied in relation to Ts. With substrate temperatures ranging from RT to 550 °C, the structural transition of the films is a-ZrO2 (below 250 °C) → m-ZrO2 with a little a-ZrO2 (450 °C) → m-ZrO2 with a little t-ZrO2 (550 °C). The roughness exponent α is 1.53 ± 0.02, 1.04 ± 0.01, 1.06 ± 0.05, 1.20 ± 0.03 for ZrO2 thin films deposited at RT, 250 °C, 450 °C, and 550 °C, respectively. Quantitative surface characterization by spatially resolved 1DPSD analyses identified three different growth mechanisms of surface morphology for ZrO2 thin films deposited at RT, 250∼450 °C and 550 °C. The evolution and interactions of surface roughness and microstructure are discussed in terms of surface diffusion, grain growth, and flux shadowing mechanisms.