Mechanical wafer alignment detection for bonding process

A method for forming a semiconductor structure, comprising:

• forming a first interconnect structure along a front-side surface of a first wafer;
• loading the first wafer and a second wafer onto a bonding platform such that the second wafer overlies the first interconnect structure;
• performing a mechanical alignment process to align the second wafer over the first wafer, wherein the mechanical alignment process comprises guiding the second wafer over the first wafer by virtue of a plurality of wafer pins such that the plurality of wafer pins contact the first wafer and/or the second wafer at a plurality of alignment positions, wherein the wafer pins are separate from the first and second wafers;
• bonding the first wafer to the second wafer such that a center of the first wafer is laterally offset from a center of the second wafer by a non-zero distance;
• and
• determining an overlay (OVL) shift between the first wafer and the second wafer, wherein determining the OVL shift comprises moving the plurality of wafer pins from a plurality of initial positions to a plurality of measurement positions and determining a difference between the plurality of alignment positions and the plurality of measurement positions.

A method for forming a semiconductor structure, comprising:

• forming a plurality of semiconductor devices on a front-side surface of a first wafer;
• forming an interconnect structure along the front-side surface of the first wafer;
• providing a second wafer, wherein the second wafer overlies the interconnect structure;
• performing an alignment process on the second wafer and the first wafer by virtue of a plurality of wafer pins, wherein a plurality of motors associated with the wafer pins are configured to move the wafer pins across a corresponding track during the alignment process, wherein a plurality of first parameters are associated with the wafer pins during the alignment process, and wherein a center of the second wafer is laterally offset from a center of the first wafer by a first lateral distance after the alignment process;
• bonding the second wafer to the first wafer such that the center of the first wafer is laterally offset from the center of the second wafer by a second lateral distance different than the first lateral distance;
• performing an overlay (OVL) measurement process on the first and second wafers by virtue of the plurality of wafer pins, wherein the plurality of motors associated with the wafer pins are configured to move the wafer pins across the corresponding track during the OVL measurement process, wherein a plurality of second parameters are associated with the wafer pins during the OVL measurement process;
• and
• determining an OVL shift by performing a comparison between the first parameters and the second parameters, wherein the OVL shift corresponds to a difference between the first lateral distance and the second lateral distance.