Low temperature wafer bonding for wafer-level 3D integration

This work presents new results on low temperature wafer bonding processes. Low temperature Cu-Cu thermo-compression bonding was successfully performed at process temperatures lower than 200°C. A process flow was developed for stacking thin Si wafers (<;25 μm) using a combination of temporary bonding with rigid carrier and plasma activated wafer bonding. Together with high accuracy optical alignment technology the two processes can be used to address the needs of manufacturing processes based on TSV technology.