Junction termination extension (JTE), A new technique for increasing avalanche breakdown voltage and controlling surface electric fields in P-N junctions

Abstract

Extremely high breakdown voltages with very low leakage current have been achieved in plane and planar p-n junctions using an ion implanted junction extension for precise control of the depletion region charge in the junction termination. Theory is presented which shows a greatly improved control of both the peak surface and bulk electric fields in reverse biased p-n junctions. Experimental results show breakdown voltages better than 95% of the ideal and at lower leakage current than the corresponding unimplanted devices. For example, diodes with a normal breakdown voltage of 1050 volts with a .5ma leakage current become 1400 volt (1450 ideal) devices with a 5µa leakage current. Applications of the technique are feasible in MOS technology, as would be expected, but are even more attractive in power devices in which the dramatically reduced surface fields are just as important as the extremely high breakdown voltages since it means more flexibility in passivation techniques, two of which we have used to date. Our results have also shown that the implant can be at a variety of temperatures with a good degree of success, extra process flexibility being the goal of these tests.