Stability of conducting amorphous RuSiO thin films under oxygen annealing
Ru1Si1O4 thin films were deposited on Si and oxidized Si substrates by reactive rf magnetron sputtering of an Ru1Si1 target in an argon/oxygen gas mixture. Two MeV He2+ backscattering spectrometry, four-point probe measurements and X-ray diffraction techniques were applied to study the films annealed at 700C in 100% dry oxygen at pressures from 0.2 to 760 Torr. The as-deposited films are 180 nm thick, X-ray amorphous and have a thickness normalized sheet resistance ?3 m? cm. After 5 min of annealing at 700C all films show some crystallization of RuO2. Above an annealing pressure of 8 Torr RuO2 crystals are clearly visible by optical microscopy. The temporal evolution investigated below 0.4 Torr shows that the film resistivity drops by one half within the first 5 min. Beyond that both the normalized sheet resistance and the fine-grain structure change little, if at all, for durations up to 4 h. No changes in film composition were detectable by backscattering spectrometry. Films grown on Si (111) vs. oxidized Si (100) substrates evolve identically, but an interfacial layer develops between the Ru1Si1O4 film and the Si (111) substrate within the first 5 min of annealing which electrically decouples the film from the substrate.
amorphous thin film crystallization ternary oxide oxygen influence