Dislocation networks in phosphorus-implanted silicon

Abstract

Abstract Observations, by transmission electron microscopy have been made on defects generated in 50 keV, high-dose (1 × 1015 to 3 × 1016 ions/em2) phosphorus-implanted silicon (111) wafers followed by 1100°C isothermal annealing in inert (dry N2) and oxidizing (wet O2) atmospheres. The formation of dislocation networks is closely associated with the generation of interstitial type dislocation loops which grow from point defects produced by ion implantation in silicon wafers. Also, dislocations grow more easily in wet O2 annealing than in dry N2. In wet O2 annealing, dislocation networks are formed by annealing within 1–2 min for samples implanted with doses above 3 × 1015 ions/cm2, and they move to deeper depths in the wafers during annealing. On the other hand, in dry N2 annealing, the critical ion dose for generation of dislocation networks is 1 × 1016 ions/cm2 and the location of dislocation networks in the wafers is usually unchanged during annealing. Such a difference in the generation and motion of dislocations between the two atmospheres can be explained in terms of the analysis of Sanders and Dobson (1969) for the vacancy flow between defect and surface. It is also shown that by implanting silicon into phosphorus-diffused layers, the generation of dislocation networks is strongly correlated with the formation of secondary defects caused by implantation and annealing.