Introduction rates and annealing of defects in ion-implanted SiO2 layers on Si

Abstract

The introduction rates and isochronal annealing behavior of structural defects created by atomic collision or ionization in SiO2 layers thermally grown on Si in O2 and steam are investigated by measuring the induced volume compaction for ion and electron bombardments. The use of compaction measurements permits study of the introduction and annealing of defects with little confusion from changes in the charge state of the defects. The structural damage created by ion energy deposited into atomic collisions is found to be complex, possibly consistent with a thermal process involving reordering of the noncrystalline network of Si–O tetrahedra, and to anneal in a slow featureless manner beginning around 300°C and returning to the original density near the original growth temperature. The structural damage created by ion or electron energy deposited into ionization is identified with broken Si-O bonds and found to anneal completely in a single well-defined stage centered at 650°C. The ionization-induced structural defect is the same for ion and electron ionization if no appreciable atomic collision energy deposition occurs simultaneously. Additional structural damage arising from an interaction between atomic collisions and ionization is demonstrated. The results demonstrate that other workers' observation of annealing in damaged oxides at 300°C corresponds to emptying of charged defects rather than annealing of the structural defects.