Thermal Transport Properties of Hybrid Bonding With Passivation

Recently, 3D hybrid bonding has drawn a lot of interest since it is an essential technology for system scaling by increasing interconnect density. However, 3D stacked structures face challenges in heat dissipation due to the limited exposed area, and the hybrid bonding becomes the main channel for not only power and signal but also heat. While the thermal characteristics of the bonding have been investigated extensively through modeling, the direct measurement remains unexplored due to the intricate structural issues. This investigation focuses on refining the precision of thermal property measurements by modifying bonding structures with a sapphire substrate, thereby facilitating the application of optical pump-probe techniques, such as time-domain thermoreflectance (TDTR). Additionally, it introduces a bidirectional heat transfer model that integrates a transducer layer and tantalum (Ta) diffusion barrier, aiming to surmount challenges in heat transfer measurement and ensure measurement accuracy. The experimental findings encompass sample preparation, validation of the insertion of a tantalum (Ta) diffusion barrier, and thermal transport property analysis using TDTR and bidirectional heat transfer modeling, resulting in the accurate extraction of key parameters and providing extensive insights into the intricate thermal behavior of bonding layers.