It was recalled that exposure to dry etching could deleteriously affect strained SiGe films by initiating misfit strain discontinuities in the film and at the interface. The annealing behavior of defects that were generated by the dry etching of Si/SiGe/Si heterostructures was studied here. Samples were annealed at 650, 700, 750 or 800C after being etched. Deep-level transient spectroscopy revealed defect levels at 0.62, 0.57, 0.56 and 0.44eV in dry-etched samples and at 0.31, 0.43, 0.56 and 0.44eV in wet-etched samples that were annealed at the above temperatures. The results were explained in terms of the appearance of point defects which condensed into dislocation loops that eventually shrank and disappeared as the annealing temperature was increased. The estimated size of the dislocation loops agreed quite well with experimentally measured values.

P.K.Swain, D.Misra, P.E.Thompson: Journal of Applied Physics, 1996, 79[8], 4402-6