A study of residual stress on rf reactively sputtered RuO 2 thin films

Abstract

Ruthenium oxide films have been deposited onto glass substrates by rf reactive magnetron sputtering at different substrate temperatures using a metallic target. The substrate temperature is varied from room temperature until 500°C. The deposited films have been characterized by X-ray diffraction and Raman scattering. From X-ray diffraction, it can be found that the film prepared at room temperature shows a random orientation. As the substrate temperature is increased, the films show a preferred orientation along the (101) direction. When the temperature is higher than 400°C, the preferred orientation changes from the (101) to the (200) direction. By analysis of the results, it has been found that the distance between the crystal planes for the films is higher than that for the powder and the difference becomes smaller when the temperature is increased. That means all the films are subject to a compressive stress and have a stress relaxation as the temperature is increased. From the Raman spectra, it can be found that the Raman peak shifts to the low Raman wave number when the temperature is decreased. This shift can be related with the residual stress in the films. Therefore, the results from the X-ray diffraction and Raman scattering can be combined for calculating the stress in the films. In this work, we will show that some information about the stress can be obtained by analysis of the Raman spectra and the X-ray diffraction. In addition, we will also show that the effects of the stress and the O/Ru ratio on the Raman peak shift can be separated.