Cooperative surface-activation strategy for low-temperature Cu/SiO2 hybrid bonding

Cu/SiO2 hybrid bonding is a potent tool to effectively mitigate data-movement issues within von Neumann architecture due to the shortening of the distance between the processor and the memory unit. To protect stacked chip performance, the realization of hybrid bonding at low temperatures (<260°C) is paramount. The essence of low-temperature hybrid bonding lies in the construction of desirable chemical structures on Cu and SiO2 surfaces. Therefore, this paper presents two types of feasible surface-activation strategies to achieve selective/non-selective hydrophilization of the Cu/SiO2 surface. Regardless of activation strategy, the Cu-Cu interface with sufficient grain growth and seamless amorphous SiO2-SiO2 interface structure were obtained at 200 °C. Moreover, the non-selective hydrophilization of Cu/SiO2 surface based on Ar/O2→NH4OH activation realized interfacial layer-free SiO2-SiO2 interface, which can provide more reliable mechanical support for next-generation data-centric applications.