The 2-step annealing method was used to investigate O precipitates and secondary defects in wafers which had been implanted with 1.5MeV As ions to a dose of 1015/cm2. After 2-step annealing, the wafers were cleaved and etched using Wright’s etchant. The O-precipitate density in lightly B-doped samples was very low. In heavily B-doped samples, the density of O precipitates was highest at 600C during the first annealing, and decreased sharply up to 800C. It increased slightly from 800 to 1000C, and was independent of implantation. The locations and types of secondary defects were determined by means of high-resolution transmission electron microscopy. Aligned dislocations were located in the vicinity of the amorphous/crystalline interface in the case of the first annealing temperature (600C). The dislocations climbed to the surface at a first annealing temperature of 700 to 1000C. This indicated that nucleation might have occurred during the first annealing at 600C, but defect growth occurred at 700C or above.

Oxygen Precipitation and Secondary Defects in Silicon by High Energy Ion Implantation and Two-Step Annealing S.H.Yoon, K.D.Kwack, B.G.Ko, J.G.Park, J.Y.Kim, H.Ruh: Journal of Applied Physics, 1999, 86[5], 2448-52