Cu pumping effect under different annealing conditions

Although TSV is regarded as a novel packaging technology, however, it is still on the developing way and many problems need to be improved and solved especially for the reliability problems. This work therefore focuses on the Cu TSV pumping effect during rapid annealing process with different temperatures of 300°C and 420°C and dwell times of 20min and 40min on the Cu-filled TSV interposer. The 200mm silicon wafer was used for TSV fabrication with 30μm in diameter and 160μm in depth. Finally, the wafer was diced into 4mm × 4mm slices for CMP (Chemical Mechanical polishing) and anneal test. The evaluation of the pumping degree was obtained by analysis of height and volume profiles before and after anneal test by the white light interferometer. It was found that Cu pumping increases with increasing annealing temperature and time. Furthermore, to verify the anneal temperature induced Cu extrusion, FEM simulation was conducted, which was well consistent with the experimental results.