BEOL Process Development Using Fast Power Cycling on Test Structures.

Power semiconductors used in automotive applications are exposed to higher temperatures and higher currents than devices used in consumer products. The qualification of these devices includes power-temperature cycling (PTC) stresses on fully integrated structures where the devices are powered on and off during cyclic temperature stresses. These PTC stresses are time consuming and can require device redesign if fails are observed. Use of a simple power cycling (PC) stress, with simple test structures, can serve as a rapid assessment tool for process development. The PC test has no decoupling of current stress from temperature stress, meaning that electromigration and thermomechanical stress effects are applied simultaneously. The determination of the physics of failure is helpful to understand how to modify the process for robustness during development cycles. In this work it is shown how different back-end architectures influences the time to failure of the devices under the PC stress tests.