Semiconductor die containing dummy metallic pads and methods of forming the same

1. A structure comprising a first semiconductor die, wherein the first semiconductor die comprises:

first semiconductor devices located on a first substrate;

first interconnect-level dielectric layers embedding first metal interconnect structures and located over the first semiconductor devices;

a first pad-level dielectric layer embedding first bonding pads and located over the first interconnect-level dielectric layers;

first edge seal structures laterally surrounding the first semiconductor devices, wherein each of the first edge seal structures vertically extends from the first substrate to a horizontal plane including bonding surfaces of the first bonding pads, and comprises a respective first pad-level ring structure that continuously extends around the first semiconductor devices; and

at least one row of first dummy metal pads embedded in the first pad-level dielectric layer, wherein the first dummy metal pads are not electrically connected to the first edge seal structures or to the first metal interconnect structures.

2. The structure of claim 1 , wherein each row of first dummy metal pads is located between a respective pair of first edge seal structures.

3. The structure of claim 1 , wherein:

the first pad-level ring structures and the first dummy metal pads have a same vertical thickness and have a same material composition; and

the first bonding pads have a same vertical thickness as the first dummy metal pads.

4. The structure of claim 1 , wherein each of the first edge seal structures comprises:

a respective metallic moat via structure that contacts a respective annular peripheral portion of a top surface of the first substrate; and

a respective vertical stack of metallic ring structures that vertically extends from an annular top surface of the respective metallic moat via structure to a bottom surface of the respective first pad-level ring structure.

5. The structure of claim 4 , wherein each of the metallic ring structures has a same vertical thickness and a same material composition as a respective one of the first metal interconnect structures having a same vertical separation distance from the first substrate.

6. The structure of claim 1 , wherein the first edge seal structures are nested among one another without direct contact between them.

7. The structure of claim 1 , wherein:

all sidewalls of the first dummy metal pads contact the first pad-level dielectric layer; and

all bottom surfaces of the first dummy metal pads contact a respective dielectric surface.

8. The structure of claim 1 , wherein each of the first pad-level ring structures comprises a plurality of straight laterally-extending segments that are parallel to a respective one of sidewalls of the first semiconductor die.

9. The structure of claim 1 , wherein:

each of the first bonding pads has a respective rectangular shape having sides with a respective length in a range from 2 microns to 60 microns; and

each of the first pad-level ring structures has a uniform width in a range from 50% of an average of lengths of sides of the rectangular shapes of the first bonding pads to 200% of the average of lengths of sides of the rectangular shapes of the first bonding pads.

10. The structure of claim 1 , wherein the first edge seal structures are electrically grounded to the first substrate.

11. The structure of claim 1 , further comprising a second semiconductor die that comprises:

second semiconductor devices located over a second substrate;

a second pad-level dielectric layer embedding second bonding pads and located over the second substrate;

at least one row of second dummy metal pads embedded in the second pad-level dielectric layer, wherein each row of second dummy metal pads is bonded to a respective one of the first edge seal structures through metal-to-metal bonding.

12. The structure of claim 11 , wherein the second semiconductor die comprises second edge seal structures laterally surrounding the second semiconductor devices and comprising a respective second pad-level ring structure that continuously extends around the second semiconductor devices, wherein each of the second edge seal structures vertically extends from the second substrate to a horizontal plane including a bonding interface between the first bonding pads and the second bonding pads.

13. The structure of claim 12 , wherein each row of first dummy metal pads is bonded to a respective one of the second edge seal structures.

14. The structure of claim 12 , wherein each of the second edge seal structures comprises:

a respective metallic moat via structure that contacts a respective annular peripheral portion of a horizontal surface of the second substrate; and

a respective vertical stack of metallic ring structures that vertically extends from an annular top surface of the respective metallic moat via structure to a horizontal surface of the respective second pad-level ring structure.

15. A method of forming a structure, the method comprising forming a first semiconductor die by:

forming first semiconductor devices over a first substrate;

forming first interconnect-level dielectric layers embedding first metal interconnect structures over the first semiconductor devices; and

forming a first pad-level dielectric layer embedding first bonding pads, first edge seal structures which comprise first pad-level ring structures, and at least one row of first dummy metal pads over the first interconnect-level dielectric layers,

wherein:

the first edge seal structures laterally surround the first semiconductor devices;

each of the first edge seal structures vertically extends from the first substrate to a horizontal plane including bonding surfaces of the first bonding pads; and

a row of first dummy metal pads is formed between a pair of first edge seal structures.

16. The method of claim 15 , wherein the first pad-level ring structures, the first dummy metal pads, and the first bonding pads are formed by forming cavities in the first pad-level dielectric layer, simultaneously depositing at least one metallic material in each of the cavities, and removing excess portions of the at least one material from above the horizontal plane including the distal surface of the first pad-level dielectric layer.

17. The method of claim 15 , further comprising

forming metallic moat via structures that contact a respective annular peripheral portion of a top surface of the first substrate and laterally surrounding the first semiconductor devices; and

forming vertical stacks of metallic ring structures that vertically extend from an annular top surface of the respective one of the metallic moat via structures to a topmost surface of the first interconnect-level dielectric material layers,

wherein each of the first edge seal structures comprises a respective one of the metallic moat via structures and a respective vertical stack among the vertical stacks of metallic ring structures.

18. The method of claim 15 , further comprising:

forming a second semiconductor die by forming second semiconductor devices over a second substrate, forming a second pad-level dielectric layer over the second semiconductor devices, and forming second bonding pads and at least one row of second dummy metal pads in the second pad-level dielectric layer; and

bonding the second semiconductor die to the first semiconductor die such that each row of second dummy metal pads is bonded to a respective one of the first edge seal structures through metal-to-metal bonding.

19. The method of claim 18 , wherein:

the method further comprises forming second edge seal structures in the second semiconductor die;

each of the second edge seal structures comprises a respective second pad-level ring structure that continuously extends around the second semiconductor devices; and

each of the second edge seal structures vertically extends from the second substrate to a horizontal plane including a bonding interface between the first metal pads and the second metal pads.

20. The method of claim 19 , wherein each row of first dummy metal pads is bonded to a respective one of the second edge seal structures.