Electrical Analysis of Wafer-to-Wafer Copper Hybrid Bonding at Sub-Micron Pitches

Multi-level back-end-of-line (BEOL) test vehicles have been produced to evaluate the performance of the Tokyo Electron (TEL) wafer-to-wafer (W2W) bonding tool platform. The designed hybrid bonding pad pitches are 1um and 0.5um which represent current and next-generation pitch technologies respectively. Step height variation induced by via level pattern density was transferred to the bonding pad layer and caused voids at the bonding interface. The integration of a dual damascene process for the via and bonding pad layers significantly reduced this step height which enabled electrical contact on larger via chain macros for evaluation.