The effects of different implantation and annealing temperatures on the structural and chemical properties of high dose oxygen-ion-implanted silicon

Substrates implanted with a high dose of oxygen ions were prepared at high (Ti = 500°C) and low (Ti = 400°C) implantation temperatures. The implanted material was then subjected to high temperature anneals in the range 1000°C < Ta < 1200°C. Physical and chemical characterization of the material was achieved using a unique combination of cross-sectional transmission electron microscopy and Auger depth profiling. The structure and composition of the top silicon layer (electrically isolated by a buried oxide) controls the eventual device performance and was found to be highly dependent on the implantation temperature. At an implantation temperature of 400°C a layer of amorphous silicon of very high oxygen content is formed at the top silicon-buried oxide interface. During annealing this layer top single-crystal silicon by a thin band of oxide and did not recrystallize epitaxially, but formed a region of polycrystalline silicon. The effect of different annealing conditions on this structure is described and a simple transport model is used to explain the observed oxygen migration.