Rapid thermal annealing has been used for fabrication of YBaCuO thin films from Cu/BaO/Y2O3 layered structures. The films were deposited on Si substrates by electron-beam evaporation. The interdiffusion at the film/substrate interface has been investigated using Auger depth profiling. With a metal barrier layer, the film showed the superconducting transition between 74-85 K. At anneal temperature above 980°C, Si was found to diffuse throughout the film and degrade the superconductivity of the films. © 1989.