MORPHOLOGY AND PHASE OF TIN OXIDE THIN-FILMS DURING THEIR GROWTH FROMTHE METALLIC TIN

Thin tin films were deposited on oxidized silicon substrates by sputte ring. Changes in both the phase and morphology of the films were studi ed as a function of the annealing process, time and atmosphere. X-ray diffraction (XRD) analysis was used to study phase evolution of the fi lms during annealing. Atomic force microscopy and scanning electron mi croscopy were employed to characterize microstructure and morphology o f the films. XRD analyses revealed phase transformations from metallic Sn to romarchite and finally to cassiterite as a function of higher a nnealing temperature. Differences in the phase transformation rate fro m metallic tin films to tin dioxide were observed between oxygen and a ir atmospheres. Little variation in grain size was observed during oxi dation annealing from metallic to oxide states in either air or oxygen . However, surface roughness of the films was strongly dependent on th e annealing atmospheres. The films annealed under air showed that surf ace roughness increased linearly with time and temperature, while the surface roughness change of the tin oxide films annealed under oxygen exhibited saturation behavior. The surface morphology change of the ti n oxide films processed in oxygen exhibited different behavior from th ose processed in air. (C) 1997 American Vacuum Society.