Advanced electrical characterization of low-temperature plasmas for wafer-to-wafer bonding processes

Abstract Plasma-Activated Wafer Bonding (PAWB) is an advantageous technique to enable low-temperature annealing of fusion-bonded substrates while maintaining high bonding energy. The use of plasma surface treatments in wafer-to-wafer (W2W) bonding enables new device integration schemes, for example in hybrid bonding applications. Despite the technological relevance and wide usage, these processes are often insufficiently characterized and understood at the fundamental level. This work presents the plasma’s electrical properties influence on plasma treated single substrates, as well as thermally annealed wafer pairs for a set of different process conditions. Installation of current-voltage probes which measure the electrical current, voltage and their respective phase angle at each electrode, enables precise characterization of the plasma process. The obtained plasma-specific parameters can be correlated with resulting oxide growth, wafer warpage and bonding energies. This approach potentially allows for enhanced process control and an improved understanding of plasma-related phenomena in the wafer bonding industry.