The mechanisms of generation and suppression of misfit dislocations in Si bulk crystal growth at the seed/crystal interface were studied. Misfit dislocations in B-doped CZ-Si crystals were suppressed when the difference in B concentration between seed and crystal was at least 9 x 1018/cm3; corresponding to 4.5 x 10-5 of misfit strain. A similar misfit strain of 3.4 x 10-5 was obtained for Ge-doped CZ-Si crystal growth. In the CZ-Si crystal growth, a transition region of impurity concentration with about 40μm in width was 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 was larger than that in epitaxial growth model in a consideration that the width of the transition region was the critical thickness of the grown layer. A preliminary new mechanism was proposed, for generation and suppression of misfit dislocations dependent on the local misfit strain at the interface during the growth from a microscopic viewpoint.

Generation and Suppression of Misfit Dislocations at the Seed/Crystal Interface in Si Bulk Crystal Growth. T.Taishi, K.Hoshikawa, Y.Ohno, I.Yonenaga: Physica Status Solidi C, 2009, 6[8], 1886-91