Platinum in-diffusion controlled by radiation defects for advanced lifetime control in high power silicon devices

The low-temperature (similar to 700 degrees C) in-diffusion of platinum (Pt) into the n-type float zone silicon guided and enhanced by radiation damage produced by implantation of helium ions was used to shape the profile of ideal recombination centers-platinum substitutionals (Pt-s). Implantation of helium ions with energies up to 11 MeV introducing different profiles of radiation defects were applied for this purpose. Both the platinum silicide (PtSi) and implanted Pt layers were compared as the sources of Pt diffusion. The full-depth distribution of in-diffused Pt was studied by monitoring the acceptor level of Pt-s(-/0) (E-C - E-T = 0.23 eV) by the current transient spectroscopy. Results show that the helium implantation significantly enhances platinum diffusion and allows its control up to the depths of hundreds of micrometers. The resulting Pt-s distribution can be controlled by the profile of radiation damage produced by helium ions while the amount of in-diffused Pt-s is set by the dose of platinum implantation. Application of the method using both the implanted and PtSi sources is demonstrated on optimization of turn-off properties of high power PiN diodes. (c) 2005 Elsevier B.V. All rights reserved.