Hybrid Bonding of Non-photosensitive Dry Films and Cu/SnAg Micro-bumps for Multilayer Glass Packaging

A novel low-temperature wafer-level hybrid bonding technique utilizing metal micro-bumps (Cu/SnAg) and non-photosensitive dry films has been developed and investigated. The bonding process is conducted at low temperatures: 160°C for the dry film and within the range of 260°C to 280°C for the micro-bumps. The micro-bumps are fabricated using conventional electroplating, while the patterning of the non-photosensitive dry film is achieved through laser ablation, bypassing the need for traditional lithography. Furthermore, optimizing the thickness of the micro-bumps, the opening dimensions of the dry film, the maximum bonding pressure, and the bonding temperature has enabled the development of a stepped control profile, which allows a seam-free bonding interface between the micro-bumps and the dry films. For demonstration, superior interconnect performance with an average tensile strength of approximately 8.11 MPa is achieved. The non-photosensitive dry film exhibits low transmission loss when applied to glass packaging due to its low dielectric constant and dissipation factor. Consequently, the proposed hybrid bonding technique provides a highly cost-effective and promising approach for future multilayer glass/PI RF 3D integration.