Hybrid bonding enables the commercialization of ultra‐fine pitch high‐density 3D packages. Cu/SiO2 hybrid bonding is the standard packing interface recently introduced in the industry. Here, the Cu/polymer hybrid bonding interface beyond Cu/SiO2 is proposed in order to have high compatibility for additional processes in the future. Ideally, polymers can provide excellent bonding strength and low permittivity, enabling high‐speed signal transmission with high reliability. To realize it, optimum polymer and additives selection and polymer bonding processing development are needed to get the desired packaging interface. Therefore, detailed materials and processing challenges are discussed to realize the successful Cu/polymer hybrid bonding. Then, the authors’ preliminary results are suggested to supplement the feasibility of the emerging bonding technology.