Secondary ion emission studies of the range profiles of implanted ions

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Abstract
The apparatus described provides a universal technique for determining the range profiles of any ion species which has been implanted in a target. In this work a previously implanted sample is bombarded in the target chamber of a stainless steel UHV system by a low energy (1 keV) ion beam. Typical beam intensity is 1 μA/cm2 on the target. The resulting sputtering process causes the target surface to recede at rates of the order of 2 Å/min. A fraction of the sputtered particles, consisting of both implanted species and target species, is ejected in the ionized state so that by using a specially modified quadrupole mass spectrometer and monitoring the intensity of these secondary ions as the surface recedes, the profile with time of the implanted species can be determined. By calibrating, this can be converted to a depth profile. Results for various ion-target combinations are presented together with an investigation of the effects on ion yield of surface contamination. Also the sensitivity of the technique for different elements is discussed.