Bonding alignment marks at bonding interface

A bonded structure, comprising:

• a first bonding layer comprising a first bonding contact, a first bonding alignment mark, and a first dielectric;
• a second bonding layer comprising a second bonding contact, a second bonding alignment mark, and a second dielectric;
• and
• a bonding interface between the first bonding layer and the second bonding layer,
• wherein the first bonding alignment mark is aligned with the second bonding alignment mark at the bonding interface, such that the first bonding contact is aligned with the second bonding contact at the bonding interface;
• the first bonding alignment mark comprises a plurality of first repetitive patterns, each of the first repetitive patterns comprises a dielectric region and a plurality of metal strips separated by adjacent dielectric regions;
• a size of the plurality of metal strips is not greater than about 25% of a size of the first respective repetitive pattern;
• and
• a first metallic portion of the first bonding alignment mark is in contact with a second metallic portion of the second bonding alignment mark at the bonding interface.

A semiconductor device, comprising:

• a first semiconductor structure comprising a substrate, a first device layer disposed on the substrate, and a first bonding layer disposed above the first device layer and comprising a first bonding contact and a first bonding alignment mark;
• a second semiconductor structure comprising a second device layer, and a second bonding layer disposed below the second device layer and comprising a second bonding contact and a second bonding alignment mark;
• and
• a bonding interface between the first semiconductor structure and the second semiconductor structure,
• wherein the first bonding alignment mark is aligned with the second bonding alignment mark at the bonding interface, such that the first bonding contact is aligned with the second bonding contact at the bonding interface;
• the first bonding alignment mark comprises a plurality of first repetitive patterns, each of the first repetitive patterns comprises a dielectric region and a plurality of metal strips separated by adjacent dielectric regions;
• and
• a size of the plurality of metal strips is not greater than about 25% of a size of the first respective repetitive pattern;
• and
• a first metallic portion of the first bonding alignment mark is in contact with a second metallic portion of the second bonding alignment mark at the bonding interface.