Stresses in sputtered RUOx thin films

RuOx thin films have been deposited by reactive sputtering in an O-2/Ar atmosphere. The films were characterized for their stress and resistivity as a function of deposition temperature (room temperature, 300 degrees C) and the O-2 content (25-100%) in the sputtering gas. Additionally, the stresses in these films were determined as a function of annealing temperature (up to 600 degrees C) using an in-situ curvature measurement technique. The as-deposited films were found to be under a state of compressive stress for all deposition conditions. The compressive stresses sharply increased with increasing deposition temperature from a value of around 200 MPa at 200 degrees C to 1400 MPa at 300 degrees C. This dramatic increase has been attributed to differences in microstructure at these deposition temperatures. The microstructural differences also led to the widely differing stress-temperature behavior during annealing of these films. For films deposited at temperatures lower than 200 degrees C, the annealing process resulted in a decrease in the compressive stress and resistivity of the films. However, films deposited at a temperature of 300 degrees C did not show any changes in the compressive stress or resistivity after annealing. The results of this study can be used to deposit RuOx thin films with low resistivity and minimal stresses. (C) 1999 Published by Elsevier Science Ltd. All rights reserved.