A scanning probe microscope was used to observe thermally induced deformation of i pm thick Cu/Ta/polyimide test structures on Si. Relative height changes in arrays of parallel Cu and polyimide lines of various aspect ratios were examined in air at room temperature before and after a 25-350-25~ thermal cycle conducted in gettered nitrogen. Grain elevation and hillock formation at grain boundaries were observed on the Cu surface as a result of the thermal cycling. It was also observed that significant sliding occurs at the Cu/Ta interface with 1 ~m wide Cu lines. Less or no sliding was observed at the interface with 10 ~m wide Cu lines.

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