Characterization of ablation plasma ion implantation

We report on the ion implantation by a new laser ion source (LIS). It is able to accelerate plasma ions towards substrates by means of a polarized accelerating gap. A pulsed excimer laser, KrF, was utilized in producing plasma by target ablation. A laser pulse energy of 70 mJ was focused onto different solid targets by a 15 cm focal length lens, obtaining an irradiance of about 3.5 × 108 W/cm2. To overcome plasma effects, such as arcs, usually occurring during the extraction phase, an expanding chamber with a hole in its end, was developed. To realize implantations, Si substrates were placed in front of the ions extracted by the plasma. The implanted samples were characterized by Rutherford backscattering spectroscopy, energy dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy and laser ablation combined to inductively coupled plasma mass spectrometry. Implantations of Al, Cu and Ge were achieved up to 80 nm at a relatively low accelerating voltage, 40 kV.