Rapid thermal annealing effects on plasma deposited SiO<inf>x</inf>:H films

The bonding configuration, hydrogen evolution and defect content of rapid thermally annealed (RTA) SiOx:H films of different initial compositions were studied. Infrared absorption measurements showed that all the hydrogen present in the films was lost at temperatures lower than 700°C without any change in the oxygen to silicon ratio of films. RTA temperatures higher than 700°C promote a change in the Si-O-Si stretching position from the initial unannealed value to the 1070-1080cm-1 range independent of the initial film composition. Electron Spin Resonance (ESR) measurements show that all the films contained two types of paramagnetic defects: E¿ (·Si¿O3) and D (·Si¿Si3). Annealing up to 700°C promotes the disappearance of the E¿ centre. For films where the D defect is present (all except the film with x ¿ 2), the concentration of these defects initially decreases for annealing temperatures of 400°C, then continuously increases for temperatures up to 700°C, getting a saturation value in the 1018-1019cm-3 range for higher temperatures. ESR characterisation suggests that annealing at higher temperatures promotes the formation of a high-quality SiO2 matrix in which Si nanocrystals are formed, the D defects being located within these nanocrystals. © 2002 Elsevier Science Ltd. All rights reserved.