Effect of the end-of-range loop layer depth on the evolution of {311} defects

The interactions between end-of-range dislocation loops and {311} defects as a function of their proximity were studied. The dislocation loops were introduced at 2600 Angstrom by a dual 1 x 10(15) cm(-2), 30 keV and a 1 x 10(15) cm(-2), 120 keV Si+ implantation into silicon followed by an anneal at 850 degrees C for 30 min. The depth of the loop layer from the surface was varied from 2600 to 1800 Angstrom and 1000 Angstrom by polishing off the Si surface using a chemical-mechanical polishing (CMP) technique. A post-CMP 1 x 10(14) cm(-2), 40 keV Si+ implantation was used to create point defects at the projected range of 580 Angstrom. The wafers were annealed at 700, 800, and 900 degrees C, and plan-view transmission electron microscopy study was performed. It was found that the number of interstitials in {311} defects decreased as the projected range damage was brought closer to the loop layer, while the number of rectangular elongated defects (REDs) increased. Experimental investigation showed that REDs are formed at the end of range. It is concluded that the interstitials introduced at the projected range are trapped at the end of range. The REDs are formed due to the interactions between the interstitials and the pre-existing dislocation loops. (C) 1999 American Institute of Physics. [S0003-6951(99)03705-5].