Switching performances of 1200 V conventional planar and trench punch-through IGBTs for clamped inductive load under extensive measurements

Abstract

This paper deals with the comparison of the switching performances of 1200 V conventional planar punch-though and trench punch-through IGBTs for a clamped inductive load. Compared to the planar device, the trench IGBT presents a higher current density and a lower on-state voltage drop. Higher current density resulting in a smaller cell size improves the conduction. However, it results also in an increase of the excess charges, which should reduce the switching performances. The use of a local lifetime control applied to the buffer layer of the trench device allows to obtain a good trade-off between the switching losses and the on-state voltage drop. A specific test circuit allows to get the collector current waveform of the device under test alone without any freewheeling diode reverse recovery influence. Then it is possible to calculate the turn-off switching losses of the device under test alone. Extensive measurements under various test conditions show that the studied trench device presents higher turn-on losses due to a high input capacitance responsible for the convex shape of the collector current waveform, but lower on-state and turn-off losses than the conventional planar device. The local lifetime control using heavy ion irradiation process presents a good efficiency in the trade-off between the on-state voltage drop and the turn-off losses than the uniform lifetime control used in third generation of planar devices.