GROWTH-KINETICS OF CHEMICALLY VAPOR-DEPOSITED SIO2-FILMS FROM SILANE OXIDATION

The growth kinetics of SiO2 thin films obtained by low-pressure chemic al vapor deposition (CVD) from SiH4/O-2/N-2. gas mixtures has been det ermined at different temperatures and flow rates. The results show tha t the film growth is originated by some intermediate species (e.g., Si OxHy) produced in the gas phase. At low temperatures the deposition ra te is limited by some homogeneous reaction with an apparent activation energy of 1.42 eV. Furthermore, the observation of critical limits wh en total pressure, oxygen/silane flow ratio, and temperature are decre ased gives support to a branching-chain mechanism of deposition. Final ly, we have observed that the deposition rate shows a hysteresis behav ior when varying the temperature within the 300-400 degrees C range, w hich has been attributed to the inhibition of silane oxidation by the Si-OH surface groups of the films grown on the reactor walls.