Effects of line size on thermal stress in aluminum conductors

The authors evaluate the aspect ratio dependence of thermal stress distribution in passivated aluminum conductors on line width and thickness as directly determined using X-ray stress measurement. Measured stresses are compared with the results of analytical and numerical simulations. It was found that they differ significantly. This difference is ascribable to the dependence of the yield stress on the line width and thickness. The yield stress increases with decreasing width and thickness. The dependence of aluminum lifetime on the width and thickness of aluminum conductors was also evaluated. This dependence is discussed with a diffusional void growth model. The experimentally obtained lifetime is well described by this model with directly measured stress.<>