TSV interposer with Au-Au diffusion bonding technology for wafer level fabrication

The Si interposer with high aspect ratio TSVs filled with Cu are fabricated for integration with the chip of fine pitch indium microbumps together to form 3D interconnects. The design of the packaging structure are discussed, and then the fabrication process (Bosch etching, Au-Au diffusion bonding, Cu electroplating and bumping laser jetting) of the Si interposer are presented. In the fabrication process of TSV interposer, the metal diffusion bonding (Au-Au wafer level bonding) technology is used for bottom-up Cu electroplating of TSVs. The Au-Au wafer level bonding with the bonding temperature of 200°C, 300°C and 400°C is utilized to investigate the bonding mechanism and bonding quality. The Au-Au wafer level bonding with no alignment is simple process, which provides the high reliability in the suceessive process.