Low-temperature radiation controlled diffusion of palladium and platinum in silicon for advanced lifetime control

摘要

Radiation defects produced by helium implantation were used to shape profiles of palladium (Pd) and platinum (Pt) atoms in-diffusing (for 20 min at temperatures 600-800 ℃) either from surface silicide (Pd_2Si, PtSi) or implanted layers. Results show that this procedure allows a strong localization of substitutional Pd and Pt at the depth where the damage produced by helium peaks. This results in local reduction of carrier lifetime by an almost ideal recombination centers - the acceptor level of substitutional Pd (E_c — 0.22 eV) or Pt (E_c — 0.23 eV). While optimum conditions for Pt in-diffusion are about 700 ℃, Pd gives the best results already at lower temperatures (600 ℃) where it also exhibits higher peak solubility. Both methods were used for optimization of turn-off properties of high power PiN diodes. The devices, where the lifetime was killed locally by Pd and Pt, exhibited similar trade-off between the static and dynamic parameters as the diodes subjected to standard He irradiation. However, for equivalent lifetime reduction, the Pd and Pt in-diffused diodes show much lower leakage and much higher thermal budget.