Boron doping of silicon by ArF excimer laser irradiation in B2H6

摘要

Boron doping of silicon using a pulsed ArF excimer laser (lgr;=193 nm, FWHM=17 ns) with B2H6has been investigated. Doping atoms are supplied mainly from both thermal and photochemical decomposition of the adsorbed layers on the surface. UV laser irradiation realizes both high surface carrier concentration (1×1021cm−3) and a very shallow junction (0.1 mgr;m). Diodes fabricated by laser doping show good electrical characteristics (nfactor=1.10, reverse current density=1×10−7A/cm2at −5 V). Thermal annealing improves the reverse current density (3×10−9A/cm2at −5 V). A numerical calculation of boron concentration profiles has been performed by solving the diffusion equation in the melted region, which is evaluated by the heat conduction equation. From this calculation the diffusion coefficient of boron in liquid phase silicon (3×10−4cm2/s) is obtained.