X-ray Determination and Finite-Element Modeling of Stress in Passivated Al-0.5%Cu Lines During Thermal Cycling.

We have measured the principal strain state of AI-0.5%Cu lines passivated with silicon nitride directly and used it to calculate the stress state. The stress was determined as the lines were thermally cycled from room temperature to 450°C. The general stress-temperature behavior shows good fundamental agreement with that calculated using finite-element methods, although the magnitude of the stresses measured with x-rays is less than that predicted by modeling due to stressinduced voiding in the lines. This is shown with a high voltage scanning transmission electron microscope (STEM) operated in the backscattering mode.