《SOS Wafer Cu Pillar Bumping Process Development for Flip Chip Package Application 》.pdf

SOS Wafer Cu Pillar Bumping Process Development for Flip Chip Package Application John, Zhiyuan Yang Peregrine Semiconductor 9380 Carroll Park Drive, San Diego, CA 92121, USA jyang@ Abstract I/O Metal Pad Cu pillar bumping process has been developed on SOS Glass Sealing (Silicon on Sapphire) wafer for flip chip package application Sapphire wafer Sapphire while in the initial packaging experiment open failure has been found. Voiding in bump pad metal has been found in package failure analysis. The cracks initiated from the BCB layer voiding have also been captured. Further investigation has confirmed that the surface roughness of bump pad metal is closely related to this failure. The voiding was formed for Deposit and pattern a layer of BCB that the bump pad metal was etched away by plating solvent UBM in bumping process. Solutions on process and bump metal structure design have been discussed and presented with evaluation experiment results in this paper. Deposit UBM (Under Bump Metallization) Introduction The Cu pillar bumping for SOS wafer is based on ele