Creep Behavior of Electroplated Cu for Through-Silicon Via Filling

As through-silicon via (TSV) is the core structural element of 3D integration or packaging, and the performance of TSV-Cu is critical for TSV reliability. This paper studied the creep behavior of TSV-Cu comprehensively. TSV-Cu sample was prepared by regular TSV process, and then nanoindention was used to determine the creep behavior of TSV-Cu at room temperature. A method of combining the constant loading rate/load test and the constant load test was introduced for the creep behavior testing. Therefore, the creep behaviors of TSV-Cu under various loading conditions were analyzed. The creep strain rate sensitivity m can also be obtained by processing the data from constant loading stage. Results show that m is independent with indentation strain rates and maximum indentation depths.