Liquid mediated direct bonding and bond propagation

Room temperature and pressure bonding is shown for wafer-to-wafer (W2W) bonding but never for small chips. Usually, thermo-compression bonding (TCB) is employed for die-to-die (D2D) and die-to-wafer (D2W) bonding for 3D and MEMS application. TCB process is itself limited by tool capability and requires pressure and temperature for bonding which is not only time consuming but can induce coefficient of thermal expansion mismatch and damage to back-end-of-line (BEOL) stacks. To address these issue, we propose a liquid mediated direct bonding approach of inorganic dielectric which can be realized at low temperature and atmospheric pressure using a fast pick and place tool.