Self-assembly and mass reflow of copper bumps for flip-chip hybridization in photonic applications

Flip-chip assembly of tin-silver-based microbumps is considered today as a reference process in advanced 3D-packaging heterogeneous integration. Two main paths can be followed in order to perform chip hybridization. Thermo-compression is the reference process but presents drawback for photonic devices integration. The mass-reflow process is an attractive alternative process which is compatible with these applications and reaches the specifications required for laser optical coupling. This paper reports the work carried out to characterized the flip chip assembly of a Photonic Integrated Circuit with a Micro-lens optical device. Morphological and mechanical analysis of the assembly will be presented and optical characterization will confirm the interest of this process for photonic device integration.