Optimization of micropillar microfabrication process for heterogeneous integration
Advanced packaging and high-density chip stacking technologies are pivotal in the evolution of microelectronics, enabling enhanced performance through heterogeneous integration. As the industry moves toward reducing bump size and pitch, the bonding methodology has shifted from solder balls to Cu pillars. Although Cu pillars with solder caps have successfully replaced solder bumps, they encounter technical limitations below 30?µm pitch, introducing new challenges, particularly in terms of thermomechanical strength, electromigration resistance, and warpage accommodation.
This project aims to develop high-density (30?µm pitch) vertical interconnections compatible with a manufacturing Die-to-Wafer assembly environment. We plan to explore an innovative micro-bumping approach based on a copper/tin pillar encapsulated in a temporary nickel cap. The Ni cap preserves the cylindrical form of the Sn structure, enhancing the bump's aspect ratio beyond the typical spherical design. We will optimize the microfabrication process to achieve pitches 30?µm. Upon completion of this work, we will have defined a process for the fabrication of ductile, fine-pitch micropillars.
Dominique Drouin
Université Grenoble Alpes
Engineering
Education
Université de Sherbrooke
Globalink Research Award