Surface activated Cu/SiO2 hybrid bonding for room temperature 3D integration

Abstract We evaluated surface activated bonding (SAB), a room temperature bonding, for hybrid surfaces bonding. At first, SAB process was evaluated on copper and silicon oxide full sheet surfaces, in order to separately study the impact of the SAB activation on both types of materials embedded in a hybrid surface layer. Then, 200 mm wafers with 2.5 μm copper pads 2.5 μm apart in a silicon oxide matrix were used to probe the impact of activation with atomic force microscopy. Two test vehicles were then manufactured in order to morphologically and electrically study the bonding interface. Thus, hybrid wafers were aligned and bonded in an EVG ® COMBOND ® equipment. Cross-sectional scanning and transmission electron microscopy characterizations were performed on both test vehicles in order to observe the bonding interface. Electrical tests were also performed at the end of full 3D integration on daisy chain structures to demonstrate a high connectivity through the bonding interface.