ANOMALOUS DIFFUSION OF LIGHTLY IMPLANTED AS INTO SI SUBSTRATE DURING N2 ANNEALING

We observe the anomalous diffusion of lightly implanted As into Si substrate during conventional furnace anneal in nitrogen ambient. The anomalous behavior shows two conspicuous features in the near-surface region and in the tail region. In the near-surface region reaching about 30-50 nm from the interface, a large number of As atoms moves toward the oxide/Si interface, and occasionally accumulates in a narrow region about 10-20 mn from the interface. Retarded diffusion is observed in the tail region. The diffusivity in the tail region increases with the increase of annealing time.