INCORPORATION OF IMPLANTED IN AND SB IN SILICON DURING AMORPHOUS LAYER REGROWTH

Annealing of indium and antimony implanted into silicon at doses sufficient to produce an amorphous layer (1014-1015 ions cm -2) has been studied using high-energy Rutherford backscattering. Annealing of these amorphous layers followed the behavior reported for layers formed by silicon ion bombardment and has a pronounced influence on both the retention and lattice-site location of the impurities, with marked differences between substrates of (111) and (100) orientation. Following epitaxial regrowth on both orientations at 550°C substitutional concentrations in excess of the solid solubility were observed. Impurity redistribution was not detected at this annealing temperature nor for 940°C annealing of (100) and (110) substrates, but migration toward the surface was observed after high-temperature annealing of (111) material. This resulted in a loss of ∼60% of implanted In after 1 h annealing, whereas antimony accumulated behind the native thermal oxide. Impurity atoms continued to migrate after lattice annealing had ceased, and it is proposed that the extended defect structure, which is unique to amorphous layers on (111) substrates annealed at high temperatures, provided the means for this out-diffusion. Two-step annealing of (111) material at 550 and 940°C resulted in a stable impurity distribution, consistent with the absence of this defect structure.