Process Development of Ultra-Fine Pitch High Density Micro Bumps

Fine pitch bumping is the key enabling technology to achieve vertical interconnect in electronic packaging and integration. Cu pillar bump with Cu/Ni/SnAg structure is the widely accepted bump scheme to achieve ideal bump electrical and mechanical performance. In this paper, we report our latest results on the 30 um pitch Cu pillar bump development. The critical process steps, including bump lithography, electroplating, seed layer etching, reflow, are investigated. Good Cu pillar bump profile in 30 um pitch is successfully achieved through the optimization of the process. A typical application using the developed bumping process has been demonstrated.