The segregation of B to extended defects during thermal annealing was studied using secondary ion mass spectrometry and cross-sectional transmission electron microscopy. Wafers of Czochralski-type material with a B concentration of 3 x 1017/cm3 were implanted with 50keV Si ions, to doses ranging from 5 x 1013 to 2 x 1015/cm2, and were then annealed at 720, 820 or 870C in N for various times. The evolution of B segregation peaks to 3 types of dislocation loop: end-of-range dislocation loops, clamshell defects, and projected-range defects, was closely related to the evolution of the dislocation loops. As the annealing temperature and time were increased, the B segregation peaks grew, remained stable, and then disappeared; together with the dislocation loops. During lower-temperature annealing, the B segregation peaks grew more slowly and reached higher peak concentrations. In addition to B segregation to dislocation loops, B segregation to {311} defects was also found. The peak for B segregation to {311} defects was unstable, and dissolved completely after annealing (820C, 600s). An analytical model was developed, for B segregation to end-of-range dislocation loops under equilibrium conditions, by taking account of the average radius and areal density of the end-of-range dislocation loops. The energy of B segregation to end-of-range dislocation loops was found to be 0.75eV.

Boron Segregation to Extended Defects Induced by Self-Ion Implantation into Silicon. J.Xia, T.Saito, R.Kim, T.Aoki, Y.Kamakura, K.Taniguchi: Journal of Applied Physics, 1999, 85[11], 7597-603