Semiconductor structure and method for forming same

A method for forming a semiconductor structure, comprising:

• providing a first wafer, wherein the first wafer comprises a first substrate and a first dielectric layer on the first substrate;
• forming an isolation ring structure in the first substrate;
• forming a pad groove in the first substrate and the first dielectric layer, wherein the pad groove extends through the first substrate along a direction from the first substrate to the first dielectric layer and extends into a partial thickness of the first dielectric layer, and the pad groove is surrounded by the isolation ring structure in the first substrate;
• forming a pad structure in the pad groove;
• providing a second wafer, wherein the second wafer comprises a second substrate and a second dielectric layer on the second substrate;
• orienting the first dielectric layer toward the second dielectric layer;
• inverting the first wafer on the second wafer;
• and
• bonding the first wafer to the second wafer.