Barrier structure against corrosion and contamination in three-dimensional (3-D) wafer-to-wafer vertical stack

1. A wafer bonding method to form integrated chips, comprising:

selectively depositing a plurality of metallic lines into interlevel dielectrics (ILDs) on opposing surfaces of adjacent wafers;

depositing at least a barrier line on an outer edge of each of the opposing surfaces of the adjacent wafers;

selectively aligning the adjacent wafers to form a stack;

bonding exposed portions of the metallic lines on the opposing surfaces of the adjacent wafers to establish electrical connections between active integrated circuit (IC) devices on the adjacent wafers; and

bonding the barrier lines on the opposing surfaces of the adjacent wafers to form a barrier structure on the outer edge of the adjacent wafers, wherein the bonded wafers includes a plurality of individual die and the barrier structure is formed on the outer edge of the bonded wafers to protect internal die from corrosion, contamination and crack propagation when the bonded wafers are cut into individual die.

2. The wafer bonding method as claimed in claim 1 , wherein the metallic lines are Copper (Cu) bonding pads.

3. The wafer bonding method as claimed in claim 1 , wherein the metallic lines are surrounded by a dielectric recess.

4. The wafer bonding method as claimed in claim 1 , wherein the barrier structure is a dense grid of connected copper (Cu) lines in a checkerboard pattern erected on the outer edge of usable die.

5. The wafer bonding method as claimed in claim 4 , wherein the barrier structure is erected on the outer edge of usable die using an edge reticle.

6. A wafer bonding method to form integrated chips, comprising:

selectively depositing a plurality of metallic lines into interlevel dielectrics (ILDs) on opposing surfaces of adiacent wafers;

depositing at least a barrier line on an outer edge of each of the opposing surfaces of the adiacent wafers;

selectively aligning the adiacent wafers to form a stack;

bonding exposed portions of the metallic lines on the opposing surfaces of the adjacent wafers to establish electrical connections between active integrated circuit (IC) devices on the adjacent wafers; and

bonding the barrier lines on the opposing surfaces of the adjacent wafers to form a barrier structure on the outer edge of the adjacent wafers, wherein the bonded wafers correspond to a single die and the barrier structure is formed by one or more barrier lines deposited on the outer edge of the single die to protect the single die from corrosion, contamination and crack propagation, wherein the barrier lines correspond to concentric copper (Cu) guard rings deposited on the perimeter of the single die to serve as passivation barriers.

7. A method of forming a three-dimensional (3-D) integrated chip system, comprising:

forming a first wafer to include one or more integrated circuit (IC) devices, a first set of metallic lines deposited into a first interlevel dielectric (ILD) on a surface of the first wafer, and a first barrier line deposited on an outer edge of the surface of the first wafer;

forming a second wafer to include one or more integrated circuit (IC) devices, a second set of metallic lines deposited into a second interlevel dielectric (ILD) on a surface of the second wafer, and a second barrier line deposited on an outer edge of the surface of the second wafer;

bonding exposed portions of the first set of metallic lines to exposed portions of the second set of metallic lines to establish electrical connections between active IC devices on the first and second wafers; and

bonding the first barrier line to the second barrier line to form a barrier structure on the outer edge of the first and second wafers, wherein the bonded wafers includes a plurality of individual die and the barrier structure is formed to protect internal die from corrosion, contamination and crack propagation when the bonded wafers are cut into individual die.

8. The method as claimed in claim 7 , wherein the sets of metallic lines include Copper (Cu) bonding pads.

9. The method as claimed in claim 7 , wherein the barrier structure is a dense grid of connected copper (Cu) lines in a checkerboard pattern erected on the outer edge of usable die.

10. The method as claimed in claim 9 , wherein the barrier structure is erected on the outer edge of usable die using an edge reticle.

11. A method of forming a three-dimensional (3-D) integrated chip system, comprising:

forming a first wafer to include one or more integrated circuit (IC) devices, a first set of metallic lines deposited into a first interlevel dielectric (ILD) on a surface of the first wafer, and a first barrier line deposited on an outer edge of the surface of the first wafer;

forming a second wafer to include one or more integrated circuit (IC) devices, a second set of metallic lines deposited into a second interlevel dielectric (ILD) on a surface of the second wafer, and a second barrier line deposited on an outer edge of the surface of the second wafer,

bonding exposed portions of the first set of metallic lines to exposed portions of the second set of metallic lines to establish electrical connections between active IC devices on the first and second wafers; and

bonding the first barrier line to the second barrier line to form a barrier structure on the outer edge of the first and second wafers

wherein the bonded wafers correspond to a single die and the barrier structure is formed by one or more barrier lines deposited on the outer edge of the single die to protect the single die from corrosion, contamination and crack propagation, wherein the barrier lines correspond to concentric copper (Cu) guard rings deposited on the perimeter of the single die to serve as passivation barriers.

12. A method of forming a three-dimensional (3-D) integrated chip system, comprising:

forming a first wafer to include one or more active integrated circuit (IC) devices;

forming a second wafer to include one or more active integrated circuit (IC) devices;

depositing first metallic lines into interlevel dielectrics (ILDs) on opposing surfaces of the first and second wafers at designated locations to serve as wafer bonding pads and to establish electrical connections between active IC devices on the first and second wafers, when the first and second wafers are bonded; and

depositing second metallic lines on an outer edge of opposing surfaces of the first and second wafers to form a barrier structure, when the first and second wafers are bonded, wherein the barrier structure is a dense grid of connected copper (Cu) lines in a checkerboard pattern erected on the outer edge of usable die within the bonded wafers.

13. The method as claimed in claim 12 , wherein the first metallic lines include a plurality of Copper (Cu) bonding pads.

14. The method as claimed in claim 12 , wherein the second metallic lines include a plurality of Copper (Cu) barrier lines deposited on the outer edge of the first and second wafers to protect active IC devices from corrosion and contamination.

15. The method as claimed in claim 12 , wherein the barrier structure is erected on the outer edge of usable die using an edge reticle.

16. A method of forming a three-dimensional (3-D) integrated chip system, comprising:

forming a first wafer to include one or more active integrated circuit (IC) devices;

forming a second wafer to include one or more active integrated circuit (IC) devices;

depositing first metallic lines into interlevel dielectrics (ILDs) on opposing surfaces of the first and second wafers at designated locations to serve as wafer bonding pads and to establish electrical connections between active IC devices on the first and second wafers, when the first and second wafers are bonded; and

depositing second metallic lines on an outer edge of opposing surfaces of the first and second wafers to form a barrier structure, when the first and second wafers are bonded, wherein the bonded wafers correspond to a single die and the barrier structure is formed to protect the single die from corrosion, contamination and crack propagation,

wherein the second metallic lines correspond to concentric copper (Cu) guard rings deposited on the perimeter of the single die to serve as passivation barriers.

17. A method comprising:

selectively depositing a plurality of metallic lines on opposing surfaces of adjacent wafers, wherein the adjacent wafers include a first and second wafer and the plurality of metallic lines are surrounded by a dielectric recess to ensure that the metallic lines on the first wafer contact the metallic lines on the second wafer;

selectively aligning the adjacent wafers to form a stack;

bonding the metallic lines on the opposing surfaces of the adjacent wafers to electrically connect active integrated circuit (IC) devices on the adjacent wafers; and

providing a barrier structure between outer regions of the opposing surfaces to protect the plurality of bonded metallic lines from contamination during wafer thinning.

18. A method comprising:

depositing a first barrier line on an outer edge of a surface of a first wafer having a plurality of die;

depositing a second barrier line on an outer edge of a surface of a second wafer having a plurality of die; and

bonding the first and second barrier lines to bond the first and second wafers and to form a barrier structure on the outer edge of the bonded wafer, the barrier structure protecting internal die from corrosion, contamination and crack propagation when the bonded wafers are cut into individual die.

19. A method comprising:

depositing a first set of concentric guard rings on a perimeter of a first die;

depositing a second set of concentric guard rings on a perimeter of a second die; and

bonding the first and second set of concentric guard rings to bond the first and second die and to form a barrier structure on the perimeter of the bonded die.