Copper Oxide Direct Bonding of 200mm CMOS Wafers: Morphological and Electrical Characterization

We show for the first time complete data on 200mm wafer to wafer copper oxide direct bonding of two metal levels. Both surface acoustic microscope (SAM) and cross-section scanning electron microscope (X-SEM) images taken across the bonded wafer pairs confirm the good direct bonding quality of the resulting interface. Daisy chains with up to 3200 copper to copper bonded pads and of about 50mOhm/pad, are shown to be connected successfully and its resistance value to match a target value, as well as to scale linearly with the increase of connections in the chain.