Experimental investigations of trench field stop IGBT under repetitive short-circuits operations

Robustness of IGBT transistors under repetitive short-circuit conditions is an important requirement. Short-circuit is one of the most severe stress conditions on IGBTs since a large current flows through the device while supporting whole supply voltage. In this paper, experimental results concerning the ageing of 600 V IGBT under repetitive short circuit operations are presented. A critical energy, which is dependant on test conditions, has been already pointed out which separates two failure modes. The first one, with a cumulative degradation effect, requires some 104 short circuits to reach failure and the other one leads to the failure at the first short-circuit with a thermal runaway effect. This paper is focused on the first failure mode. In order to understand the ageing mechanism, 600 V IGBT dies have been packaged by Microsemi. The packaging has been made in order to make possible the characterization of some degradations by the measurement of different electrical characteristics. In this paper, we will detail effects of device ageing on on-state voltage, short- circuit current and Al metallization degradation which leads to resistance increase.