Reliability study of thermal cycling stress on smart power devices

Abstract

In this paper, we describe a smart power device degradation behavior under thermal cycling stress. An innovative test structure was developed, which faithfully reflects a stress state caused by the smart power device during operation. From our experiment, the device degraded after millions of fast thermal cycling pulses. We discovered that via destruction was the cause of the device degradation. For the duration of thermal cycling stress, the via resistance increased gradually, and finally increased rapidly at the point of millions of cycles. A failure via was observed, which was broken into two parts. Therefore, the via disconnection was considered to be due to thermo-mechanical stress or electro-migration. Some experiments were conducted, and we demonstrated that the via destruction dominated to the thermo-mechanical stress introduced by the thermal cycling stress.

Electropolishing—A Practical Method for Accessing Voids in Metal Films for Analyses

“…When considering thin film specimens, especially structured ones, as in microelectronics applications, focused ion beam (FIB) is a widely used preparation technique for investigating general defects, including voids [23][24][25][26]. Compared to embedded mechanical cross-sections, FIB has the advantage that no time-consuming pre-preparation steps are required and that imaging is also possible between different milling steps, allowing for tomographic void analyses [27].…”