Microstructures and electrical resistivities of the RuO2 electrode on SiO2/Si annealed in the oxygen ambient

The electrical resistivity property of RuO2 thin films grown on the SiO2/Si substrate by reactive de sputtering was examined in terms of microstructure using x-ray diffraction and cross-sectional transmission electron microscopy. As the samples were annealed in the oxygen ambient over the temperature range 300-700 degrees C, the resistivity decreased from 270 to 90 mu Omega cm with increasing annealing temperature. When heat treatment was performed below 500 degrees C, the strain which accumulated in the RuO2 layer during deposition was released without significant increase in grain size. It is thought that below 500 degrees C improvement in the crystallinity plays an important role in the variation of the resistivity. Although a considerable amount of growth of RuO2 grains was achieved, the columnar structure of the RuO2 layer in the as-deposited sample remained unchanged even after annealing at 700 degrees C. The resistivity improvement above 500 degrees C was driven mainly by the grain boundary annihilation.