Micro-Raman and ion channeling study of crystal damage in Si induced by focused Co ion beam implantation

Abstract

The lattice damage of silicon produced by ion implantation at extremely high current density of 0.8 A/cm2 (2.5×1018 cm-2 s-1) was investigated. In a focused ion beam system, implantation was carried out with 70 keV Co ions, fluences of 1.2×1016 cm-2 and 6.7×1015 cm-2 into Si (111) at room temperature and elevated temperatures between 355 °C and 400 °C. Radiation damage measurements were performed by Rutherford backscattering/channeling spectroscopy and micro-Raman analysis. The radiation damage was studied as a function of pixel dwell-time and implantation temperature. The critical temperature for amorphization increases with current density. Although the fluence of the focused ion implantation was constant, crystalline layers were obtained for short and amorphous layers for long pixel dwell-times. The critical dwell-time of crystalline/amorphous transition increases with implantation temperature. From the results a typical time for defect annealing of 10-5 s at 400 °C and an activation energy of (2.5±0.6) eV were deduced.