Diode characteristics and residual deep-level defects of p+n abrupt junctions fabricated by rapid thermal annealing of boron implanted silicon

Abstract

p+n diodes were fabricated by rapid thermal annealing (RTA) of boron implanted silicon (75 keV, 2*1016 cm-2) in the annealing temperature range 700-1100 degrees C for around 7 s, and the RTA temperature dependence of electrical characteristics of these diodes was studied. Deep-level transient spectroscopy (DLTS) measurements were made to evaluate residual deep-level defects in the n-type bulk. Three electron traps E1 (Ec-0.21 eV), E2 (Ec-0.23 eV) and E3 (Ec-0.29 eV) were observed in p+n diodes fabricated by RTA at 700 degrees C. It was considered that these three traps were residual point defects near the tail of the implantation damage after RTA. Residual defect concentrations increased in the range 700-900 degrees C and decreased in the range 1000-1100 degrees C. The growth of defects in the bulk was ascribed to the diffusion of defects from the implanted layer during RTA. Concentrations of E4 (Ec-0.33 eV) and E5 (Ec-0.48 eV) observed in p+n diodes fabricated by RTA at 1100 degrees C were approximately 1012 cm-3. It was found that these residual deep-level defects observed by DLTS were inefficient generation-recombination centres since the reverse current was independent of the RTA temperatures.