Height Uniformity of Micro-Bumps Electroplated on Thin Cu Seed Layers

Abstract

In this study a quick and cost-effective approach is developed to evaluate the micro-bump height uniformity on wafer level. Our numerical simulation of bump-height distribution uses experimentally measured i-η curve, and requires no explicit knowledge of the plating bath components. Theoretical predictions are well matched with results obtained for Cu micro-bumps plated on 300 mm wafers with Cu seeds of varying thickness. The method can be easily adapted to address the challenges of fabrication of multi-layered features and different cell and electrode geometries.