Hybrid wafer bonding method and structure thereof

A hybrid wafer bonding structure, comprising:

• a first semiconductor structure including:
• a first substrate, a first dielectric layer formed on the first substrate, and a first via structure formed in the first dielectric layer and on the first substrate, the first contact via having a first contact via surface;
• a second semiconductor structure including:
• a second substrate, a second dielectric layer formed on the second substrate, and a second via structure formed in the second dielectric layer and on the second substrate, the second contact via having a second contact via surface, wherein:
• the first semiconductor structure is bonded with the second semiconductor structure, the first contact via surface is attached with the second contact via surface, and the second contact via surface and the first contact via surface have different surface areas and have an overlapped interface;
• and
• a self-barrier layer, formed on a non-overlapped surface of one or more of the first and second contact via surfaces at a bonding interface between the first and second semiconductor structures, wherein the self-barrier layer contains a multi-component oxide,
• wherein a contact hole in the first dielectric layer includes a first groove on the first substrate and a first trench connected to and on the first groove,
• a barrier layer is on an inner surface of the contact hole and a seed layer is on the barrier layer, and
• first metal impurity-doped copper is over the seed layer and in the contact hole to form the first via structure, and the first via structure includes a first switch element in the first groove and a first contact via on the first switch element.