High-power silicon P–i–N diode with cathode shorts: The impact of electron irradiation

Large-area silicon P–i–N diodes (VRRM = 4.5 kV, IFAV ≈ 3 kA, Aactive ≈ 55 cm2) were processed with cathode shorts in order to conserve the softness under reverse recovery, while employing a 10% thinner silicon wafer for a better technology curve for the static and dynamic losses. Contrarily to existing designs, the cathode shorts have approximately one order of magnitude higher surface concentration of the P+ layer than the N+ emitter. Except for the implanted N-type buffer, these shorts were processed using the dopant deposition from POCl3 and H3BO3. The diodes with and without cathode shorts have been compared for the static parameters. The dynamic behavior has been also compared at reverse recovery of a free-wheeling diode in a standard IGCT circuit. The impact of electron irradiation on the softness of the reverse recovery has been evaluated up to 125 °C.

► P–i–N diode with cathode shorts for a softer recovery using 10% thinner silicon.
► Cathode shorts have one order higher Nsurf of the P+ layer than the N+ emitter.
► No ion implantation used for the shorts – only the diffusion from POCl3 and H3BO3.
► Significant improvement of technology curve (Vf–Erec) achieved.
► Softness vs. the dose of electron irradiation has inverse temperature coefficient.