Test chip for detecting thin film cracking induced by fast temperature cycling and electromigration in multilevel interconnect systems

Temperature cycling in power ICs is a reliability hazard, even more so when electromigration is playing a role as well. The frequency of the temperature cycling is in the audio domain, which makes it impossible to test in environmental chambers. In the paper, the design and application of a novel test chip to study fast temperature cycling, electromigration and their interaction in multilevel interconnection systems is reported. Incorporated into the test chip are a heating element, a temperature sensor, and extrusion monitors. Simulation was used to study the initial stress distributions after processing and local temperature distributions in the test chip during the temperature transient. First experimental results have been obtained in the area of fast temperature cycling experiments (by using internal heating only) and electromigration experiments. Failure distributions and failure modes are discussed. Results indicate that on-chip cycling is a powerful tool to study reliability of power ICs under realistic conditions.