A Study of Atomic and Molecular Arsenic Ion‐Implanted Silicon

The properties of silicon implanted with atomic (As+) and molecular arsenic ions at the equivalent energy of 33 keV/atom are compared using transmission electron microscopy, Rutherford backscattering, secondary ion mass spectrometry, and spreading resistance techniques. Both As+ and amorphize the silicon continuously from the surface to an identical depth, but the projected range, , and range straggling, , are found to be larger for silicon implanted with than for silicon implanted with As+. This suggests that the energy loss of the ion is low with respect to the dissociation energy of the molecule. After furnace annealing, the silicon retains a lower concentration of substitutional arsenic and shows less carrier activity at the surface than the As+‐implanted silicon. The higher concentration of nonsubstitutional arsenic in the silicon enhances diffusion and causes the metallurgical junction to be deeper than the electrical junction. Junction diodes formed by rapid thermal annealing either or As+‐implanted silicon show similarly good I‐V characteristics.