Fast Thermal Cycling Stress and Degradation in Multilayer Interconnects

The thermal cycling stress method is popularly used to study the thermal mechanical effect on metallization films in VLSI applications, specially in interconnect systems of power IC. The fast thermal cycling stress method reported in this paper has several advantages compared with using a conventional oven for thermal stress. A special test chip is designed to demonstrate the application of this method. A diode in the test chip plays a part as temperature sensor. The diode thermal coefficient is determined to be 1.8mV/C. The first experiment of temperature cycling stress is done with temperature ranging to be from 46 to 286C (∆T of 240C). The failure analysis is done by SEM equipment with Backscatter Electron (BSE) detector. The results show the mechanism observed that the failure mechanism is quite similar with temperature cycling stress using a conventional oven. KeywordsThermal cycling; multilayer interconnects; chip temperature measurement; SEM; BSE