Impurity distribution profiles in ion-implanted silicon

Abstract

A p–n junction location technique for determining ion-implanted profiles of dopant ions in semiconducting substrates is described. This method allows detection of the implanted concentration up to eight orders of magnitude below the peak. Distributions of boron, nitrogen, phosphorus, and arsenic ions implanted in [Formula: see text] oriented silicon crystals as well as boron in [Formula: see text] silicon crystals are given. The samples were implanted at energies from 10 to 70 keV and were annealed during implant at 625 °C. The results are compared to theoretical estimates. In the cases of boron and arsenic in [Formula: see text] silicon, and boron in [Formula: see text] silicon, a definite maximum range Rmax is apparent. In these cases Rmax increases as the square root of the incident energy, indicating a channeling phenomenon. The phosphorus profiles do not show a maximum range, but rather decrease exponentially with depth for five orders of magnitude in concentration.