Study of Stress and Morphology of Silicon–On–Insulator by Means of Ultraviolet Reflectance Spectroscopy

Abstract

AbstractSOI material was prepared by implanting a high dose of nitrogen into crystalline silicon at an energy of 160 keY to form a buried layer of silicon nitride. Ultraviolet reflectance spectroscopy was employed to characterize the material. In the current presentation the isothermal annealing behaviour of the surface material was investigated with regard to amorphization and stress. Measured UV–reflectance of the samples are compared to simulated reflectance data which were obtained by presenting the implanted material as a layered structure with the surface layer consisting of a mixed layer of amorphous and crystalline silicon. From these simulations the percentage amorphization at each stage during the annealing cycle is quantitatively determined. Stress is qualitatively determined by considering the shift in the position of the frequencies at which reflectance maxima associated with Van Hove singularities are observed in the ultraviolet range. The annealing cycle used in this work proved to be adequate for returning the material back to single crystal status and relieving the initial stress in this layer.