The Effect of As-Implanted Damage on the Microstructure of Threading Dislocations in MeV Implanted Silicon

We measure dose dependence of as-implanted damage and density of threading dislocations formed after MeV implants into Si. The role of the damage and amorphization in the evolution of dislocation microstructure is assessed. As-implanted damge is analyzed by Rutherford Backscattering Spectroscopy (RBS) and channeling. Defect etching is used to delineate threading dislocations in near-surface regions of annealed (900C, 30 min) samples. For a variety of implants with 1.1 micron projected range (600 keV B, 1 MeV P, and 2 MeV As) we observe a sharp onset for formation of threading dislocations with a peak in dislocation density at a dose of about 1x10 sup (14) cm sup (-2), this dose depends on the ion mass. With further increase in dose, the dislocation density decreases. This decrease, however, is drastically different for the different ions; sharp (4-5 orders of magnitude) reduction for P and As implants and slow decline for B implant.