Oxide precipitate-induced dislocation generation in heavily boron-doped Czochralski silicon

Dislocation generation associated with oxide precipitates in heavily boron-doped Czochralski silicon wafers with resistivities of 9, 18, and 40 m Omega cm has been studied following prolonged isothermal annealing from 800 to 1000 degrees C. Transmission electron microscopy observations revealed (i) the critical precipitate size for punched-out dislocations to form in 9 and 18 mn cm wafers was smaller than 40 nm in 9 and 18 m Omega cm wafers, while larger than 55 nm in 40 m Omega cm samples; (ii) the precipitate density was higher than 10(12) cm(-3) in 9 and 18 m Omega cm wafers, and below 10(11) cm(-3) in 40 m Omega cm wafers annealed at 800 and 900 degrees C, respectively. The strain around a precipitate was estimated and it was concluded that the higher supersaturation of silicon interstitials in the 9 and 18 m Omega cm wafers was due to the higher precipitate density, which in turn was likely to be the main cause of the reduction in critical precipitate size. (C) 1999 The Electrochemical Society. S0013-4651(98)12-009-8. All rights reserved.