Electrical overlay measurement methods and structures for wafer-to-wafer bonding

A method of bonding a first wafer and a second wafer, comprising:

• providing a first wafer including a first two-dimensional array of first semiconductor dies, wherein each of the first semiconductor dies comprises a respective set of first metal bonding pads and a first alignment diagnostic structure located at a same level as the first metal bonding pads;
• providing a second wafer including a second two-dimensional array of second semiconductor dies, wherein each of the second semiconductor dies comprises a respective set of second metal bonding pads and a respective set of second alignment diagnostic structures comprising a central alignment diagnostic structure and peripheral alignment diagnostic structures that surround the central alignment diagnostic structure, wherein the second alignment diagnostic structures are located at a same level as the second metal bonding pads;
• overlaying the first wafer and the second wafer;
• applying opposite polarity current or voltage between the first alignment diagnostic structure and the central alignment diagnostic structure to electrostatically attract the first alignment diagnostic structure and the central alignment diagnostic structure;
• applying a same polarity current or voltage between the first alignment diagnostic structure and the peripheral alignment diagnostic structures to electrostatically repel the first alignment diagnostic structure from the peripheral alignment diagnostic structure;
• and
• bonding the second wafer to the first wafer.