Achievement of Contact Stabilization to Al Pads in the Wafer Level Burn-in (WLBI) Technology

We developed the WLBI technology that was applicable to Al pads wafer. Contact stabilization between Al pads and bumps was one of important subjects for developing WLBI probe. One problem was the high contact resistance for a while after making contact at room temperature, and another problem was the increase of the contact resistance during high temperature (125°C) . In this paper, we report that we analyzed those problems and that those problems were solved by making the bumps surface ruggedness and applying suitable materials to the bumps surface.