High-energy Implants of Aluminum In Czochralski and Floating Zone Grown Silicon Substrates

Aluminum ions at 100 MeV were implanted into floating zone (FZ) and Czochralski (CZ) grown Si substrates. At this energy the implanted ions are located at a depth of about 40 mum so to minimize the influence of the surface on the subsequent thermal treatment. In FZ samples the electrically active dose, as measured by spreading resistance profilometry, is independent of the annealing time at 1200-degrees-C, but in the CZ samples it decreases considerably with time. Secondary ion mass spectrometry analysis in CZ samples has revealed the presence of a multipeak structure around the projected range region for both Al and O signals. In the FZ the structure is just detectable. The results imply that the Al-O complex formation is, of course, enhanced by the large content of oxygen but that it is catalyzed by the damage created during the implant. In contrast the carrier profiles coincide in both CZ and FZ substrates doped by predeposition of Al from a solid source and subsequent diffusion; i.e. in damage free samples.