In recent years, CEA-LETI emerged as a leading force in the development of advanced microelectronic manufacturing processes. A key focus has been on wafer-to-wafer Cu/SiO2 hybrid bonding (HB) process, an emerging technology increasingly employed for producing compact, high performance and multifunctional devices. Before bonding, a crucial surface activation step is necessary to enhance the mechanical strength of the assembled structures. Different approaches have been developed, and the most used in the industry is N2-plasma activation. However, this process remains controversial due to undesirable effects, the formation of Cu nodules at the bonding interface between particularly electrical pads and the passivation of Cu pads with chemical complexes. These issues can significantly compromise the electric properties and reliability of devices. In collaboration with STMicroelectronics and IM2NP, this PhD aims at studying the impact of plasma activation on Cu/SiO2 HB integrations.