Ultra-low on-resistance 60-100 V superjunction UMOSFETs fabricated by multiple ion-implantation

Abstract

We propose new low-voltage UMOSFETs with superjunction (SJ) structures to achieve ultra-low on-resistance. The present SJ structure has been formed by multiple boron ion implantations with varied energies up to 2 MeV. This technique enabled us to obtain p-columns with flat sidewalls, which minimize the interference to the drift conduction. The SJ diodes have clearly indicated the breakdown voltage enhancement, as expected, from the SJ characteristics. Drastic on-resistance reduction was demonstrated for the SJ-UMOSFETs with a breakdown voltage of 78 V.