Depth profilometry of sputtered Ni ions implanted in Ti using pulsed argon and nitrogen plasmas

A brief description is given of a prototype 4 pi ion implanter (4 pi II) which uses a compact electron cyclotron resonance (ECR) source for plasma production. In 4 pi II pulsed Ar and N-2 plasmas were used to sputter and ionize Ni from a target biased to -2 kV. Ions are extracted through a grounded grid, which surrounds the sample under implantation, and are accelerated toward the samples biased to -30 kV. X-ray photoelectron spectroscopy was used to measure the depth profile and atomic concentration of the species constituting the first 50 nm of the Ti sample surface. The measured Ni profile can be modelled by considering the implantation of 30 keV ions together with deposition and ion mixing. The difference between the profile shapes for samples processed in Ar and N-2 plasmas can be attributed to the difference in the characteristics of the processing plasma. Traces of Cr and Fe impurities were also detected on the surface of the sample implanted in the Ar plasma. These impurities most likely originated from the chamber wall or the stainless steel grid used for controlling potential distribution in the 4 pi ion implanter. (C) 1997 Elsevier Science S.A.