AVOIDING END-OF-RANGE DISLOCATIONS IN ION-IMPLANTED SILICON

End-of-range dislocations, which occur from amorphizing implants, are formed if a critical amount of damage is present in the amorphous-crys talline transition region. Here, we investigate the role of the substr ate temperature and of the implant energy in residual damage formation . 100 keV Ge implants at room and liquid-nitrogen temperature and ultr a-shallow implants of 20 keV Ge and As and 5 keV B at room temperature were performed at different doses above the amorphization threshold. Samples were subsequently annealed at 200, 400, 600 and 900 degrees C. From the study of the low temperature annealing behaviour of the impl anted samples by Rutherford backscattering channelling, we determine t he number of displaced atoms located inside amorphous zones in the amo rphous-crystalline transition region. We conclude that this number sho uld be maximized to avoid dislocation formation. Plan-view transmissio n electron microscopy is used to analyse implanted samples after the l ast annealing at 900 OC for 15 min. All the ultrashallow implanted sam ples are found to be dislocation free.