Activation of As Atoms in Ultrashallow Junction during Milli- and Microsecond Annealing Induced by Thermal-Plasma-Jet Irradiation

摘要

We irradiated a micro-thermal-plasma-jet (μ-TPJ) to an As-implanted Si wafer surface to form an ultrashallow junction (USJ). A high-power-density TPJ for microsecond rapid thermal annealing (RTA) was generated by using a small orifice of 0.8 mm diameter instead of 2.0 mm to concentrate the TPJ. The μ-TPJ could anneal the Si wafer surface at a temperature as high as 920 K for 340μs. By reducing the annealing duration (t_a) from 1.2 ms to 340μs, the sheet resistance (R_s) of the As_2~+-implanted Si wafer decreased from 1520 to 1287 Ω/sq. In addition, the chemical bond states of As at the very surface were measured by X-ray photoelectron spectroscopy (XPS) and the fraction of activated As was estimated to be ～15% larger than that in the case of millisecond annealing. Surface As atoms in Si wafers were more efficiently activated by a microsecond annealing than a millisecond annealing owing to the suppression of diffusion and clustering.