Effect of pre-CMP annealing on TSV pumping in thermal budget and reliability test

Cu pumping is a potential reliability issue for through silicon via (TSV) based 2.5D and 3D integration, due to the CTE mismatch between silicon and copper. In this paper, we report the reliability assessment of Cu pumping treated at different annealing conditions. Cu pumping is simulated by finite element method to compare the effect of the overburden layer. The pumping of TSVs having a diameter of 10 μm and a depth of 100 μm has been fabricated and characterized using a white light optical profiler. According to the thermal budget evaluation and TC, HTS and HAST test results, higher annealing temperature is beneficial to control the Cu pumping and improve the TSV reliability.