Sample Preparation Technique for Bond Pad IMD (Inter-Metal Dielectric) Damage Observation

Wire bonding is the most highly used interconnection technology in the packaging of integrated circuits. One of the potential risks of wire bonding is the damage on the oxide layers underneath the bond pad. Oxide damage monitoring is necessary to ensure bonding has no impact on the oxide layers under the bond pad. Since the oxide layer is not seen by visual inspection, bond pad stripping is necessary. Three bond pad stripping chemicals KOH, Aqua regia, and phosphoric acid were investigated in this study. Results obtained by dipping the chemicals at different temperatures, and time scales will be given. An optical microscope (OM) and scanning electron microscope (SEM) are used to observe the oxide conditions from the top view. To understand the mechanism of the oxide damage caused by wire bonding, a focused ion beam was used to observe the cross-section of the defect.