Generation and suppression of misfit dislocations at the seed/crystal interface in Si bulk crystal growth

Abstract

AbstractMechanism of generation and suppression of misfit dislocations in Si bulk crystal growth at the seed/crystal interface is studied. Misfit dislocations in B‐doped CZ‐Si crystal growth are suppressed when the difference in B concentration between a seed and the grown crystal is at least 9 × 1018 cm–3, corresponding to 4.5 × 10–5 of misfit strain. Similar misfit strain of 3.4 × 10–5 was obtained in Ge‐doped CZ‐Si crystal growth. In the CZ‐Si crystal growth, a transition region of impurity concentration with about 40 μm in width is formed at the seed/crystal interface in both dislocation‐free and dislocated crystals by diffusion of impurity atoms from the seed. From a macroscopic viewpoint at the seed/crystal interface, the critical misfit strain in Si bulk crystal growth is larger than that in epitaxial growth model in a consideration that the width of the transition region is the critical thickness of the grown layer. We propose a preliminary new mechanism of generation and suppression of misfit dislocations dependent on the local misfit strain at the interface during the growth from a microscopic viewpoint. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)