Temperature effect on structure and surface morphology of indium tin oxide films deposited by reactive ion-beam sputtering

Indium tin oxide (ITO) films were deposited by reactive ion-beam sputtering. The relationship among the surface morphology, the resistivity ρ of the films, the substrate temperature TS and the film thickness tF was investigated. The heat power from the ion source during the sputtering was 265 W. TS increased from 30 to 145 °C with an increase of tF. The films thinner than 187 nm at TS lower than 120 °C were amorphous, the film surface was as smooth as the substrate. The films deposited at TS in the range between 135 and 145 °C were polycrystalline. So, the films thicker than 375 nm were in a multilayer structure of a polycrystalline layer on an amorphous layer. The surface of the polycrystalline films became rough. ρ of the films suddenly decreased at tF of 375 nm, where the structure of the films changed. Next, the amorphous films with tF of 39 nm were annealed in the atmosphere. The film structure changed to a polycrystalline structure at annealing temperature TA of 350 °C. However, the surface roughness of all the films was almost same. As a result, the substrate temperature during the sputtering was important for the deposition of the films with a very smooth surface.