Sheet resistivity and transmission electron microscope investigations of BF+2 -implanted silicon

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Abstract
Sheet resistivities of post‐implantation annealed BF+2 ‐implanted silicon were measured by four‐point probe method as a function of implantation dose, annealing temperature, and time. The resistivities of the implanted layer were found to be lower for samples annealed at higher temperature as well as irradiated to higher dose. Detailed transmission electron microscope investigations were made for samples irradiated to 1×1014 cm−2. Disordered zones were found to transform to microscopic clusters and small Frank loops on {111} planes upon 600 °C annealing. The rodlike defects in samples annealed at 700–800 °C are identified to be elongated perfect dislocation loops lying on or near {111}, interstitial in nature, with Burgers vectors b = 1/2 〈110〉 perpendicular to their elongated directions. They disappeared upon 900 °C annealing. The dislocation loops that coexisted with the rodlike defects consisted of interstitial perfect prismatic loops and extrinsic Frank loops, mainly hexagonal or circular in shape. They persisted after 900–1000 °C annealing. Half circular faulted loops and larger faults were found in 1000–1200 °C annealed samples. The loops were identified to be extrinsic Frank loops, lying on {111}. The formation and growth of these loops is likely related to the effect of oxidation in annealing.