Thermal characterization of power devices by scanning thermal microscopy techniques

The scanning thermal microscope (SThM) is used for investigating chip tempe ratures of power devices under operating conditions enabling the localizati on of failure-induced hot spots. In this paper, we present the measurement of the temperature distribution on the surface of a free-wheeling diode of an IGBT. A new modulation technique implemented into the SThM for the deter mination of local quantitative thermal conductivities, the so-called 3 omeg a technique, is also used for further analyses of defective power devices. With this technique, a non-uniformity of the thermal conductivity in the mi crometer range could be found at the anode side of a GTO. (C) 1999 Elsevier Science Ltd. All rights reserved.