Radiation Induced Structural Changes in Amorphous SiO2: I. Point Defects

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Abstract
Potential sources of damaging radiation present in technological processing steps (lithography, ion implantation, plasma assisted processing) are reviewed and the magnitude of the radiation present is estimated. Radiation induced “intrinsic” point defects in a-SiO2 are discussed with particular reference to their charge states. The kinetics of defect creation are studied for both the cases of ionizing and displacive radiation. The annealing kinetics of neutral and charged defects indicate that diffusion of molecular species (H2, H2O, O2) is involved and that temperatures ∼350°C are adequate to “passivate” them. Defect reactivation studies demonstrate clearly that point defects are not irreversibly removed from the a-SiO2 network unless temperatures ∼850°C are attained. At such temperatures, structural reorganisation occurs resulting in bond reorganisation and absorption of the defect.