On the annealing of damage produced by boron ion implantation of silicon single crystals

Abstract

Abstract Using the techniques of Rutherford scattering, electron microscopy and infra-red absorption, the damage produced by implantation of 100 to 400 keV boron (11B) ions in silicon single crystals, held at room and liquid nitrogen temperatures, has been examined, and the annealing behaviour investigated. The rapid annealing of disorder in the range between room temperature and 325°C, as observed by the Rutherford scattering of channelled analysing particle beams, correlates with a shrinkage of the 1. 8μ divacancy infra-red absorption band, and with a coarsening of some of the defects observed in the electron microscope. Amorphous zones observed in samples implanted with 1015 boron ions/sq. cm. at liquid nitrogen temperature do not anneal until temperatures in the vicinity of 450 °C are attained. The consequences of aggregation of point defects, first as small crystallographic clusters, for temperatures in the vicinity of 300 °C, and then as large circular dislocation loops following isochronal anneals up to 1000 °C, have been observed for specimens implanted at liquid nitrogen temperature. Details of this, and of substantial differences observed in room temperature implanted samples are discussed.