A Study on the Surface Activation of Plasma Treatment for Hybrid Bonding Joint Interface

This study focuses on the surface activation and processing steps required for copper-dielectric hybrid bonding to form dielectric bonding with high strength. Conventionally, contact angle was used to identify the degree of surface activation. However, the results become ineffective when contact angle less than 5 degrees. Therefore, we developed chemical force microscopy (CFM) to define the activation level, surface energy, and correlated to final bonding quality. The plasma treatment parameters (including power, gas, flow rate, etc.) were optimized to produce the highest surface energy. Different plasma treatment conditions resulted in significant differences in surface energy. Together with the CSAM yield rate, both were monitored simultaneously and the results showed a consistent trend. High surface energy can significantly improve the CSAM yield rate. This study is beneficial for the development of hybrid bonding, as the optimized surface activation process produces significantly higher surface energy than the industry standard activation process.