Semiconductor structure and manufacturing method thereof

A semiconductor structure, comprising:

• a first semiconductor wafer comprising:
• an upper dielectric layer, wherein the upper dielectric layer is a single layer;
• and
• at least one upper metallization structure embedded in the upper dielectric layer;
• and
• a second semiconductor wafer comprising:
• a lower dielectric layer forming a dielectric-to-dielectric bond with the upper dielectric layer;
• and
• at least one lower metallization structure embedded in the lower dielectric layer and forming a metal-to-metal bond with the upper metallization structure, the dielectric-to-dielectric bond and the metal-to-metal bond are located at different levels and between the first semiconductor wafer and the second semiconductor wafer, a top surface of the upper dielectric layer is coplanar with a top surface of the upper metallization structure, and an interface between the lower metallization structure and the upper metallization structure is substantially parallel to an interface between the lower dielectric structure and the upper dielectric structure.