Hybrid bonding structure and hybrid bonding method

Abstract

This invention provides a hybrid bonding structure comprising a first copper pad and a second copper pad, wherein a portion of the first copper pad overlaps and contacts a portion of the second copper pad, and a compound layer of copper and a phenyl compound remains on the non-overlapping surfaces of the first and second copper pads. This invention further provides a hybrid bonding method comprising forming a first copper pad, coating the surface of the first copper pad with a phenyl antioxidant solution to form a second copper pad, coating the surface of the second copper pad with a phenyl antioxidant solution, and bonding the first and second copper pads together.

Claims

1. A hybrid bonding structure comprising: a first copper pad and a second copper pad, wherein a portion of the first copper pad overlaps and contacts a portion of the second copper pad, and a copper and phenyl compound layer remains on the non-overlapping surfaces of the first copper pad and the second copper pad, while the overlapping contact surfaces between the first copper pad and the second copper pad do not have a copper and phenyl compound layer.

2. The mixed-bonded structure as described in claim 1, wherein the copper and phenyl compound layer comprises: a copper and benzotriazole compound layer, or a copper and diphenyl disulfide compound layer.

3. The hybrid bonding structure as described in claim 1, wherein the thickness of the copper and phenyl compound layer is between 10 and 400 angstroms.

4. The hybrid bonding structure as described in claim 1, wherein the interface resistance of the first copper pad and the second copper pad after bonding is less than 0.025 ohms.

5. A hybrid bonding method comprising: forming a first copper pad; coating a surface of the first copper pad with a phenyl antioxidant solution; forming a second copper pad; coating a surface of the second copper pad with a phenyl antioxidant solution; and bonding the first copper pad and the second copper pad together, wherein after bonding, a compound layer of copper and phenyl remains on the non-overlapping surfaces of the first copper pad and the second copper pad, and no compound layer of copper and phenyl is present on the overlapping contact surfaces of the first copper pad and the second copper pad.

6. The method as described in claim 5, wherein the phenyl antioxidant solution is applied to the surfaces of the first copper pad and the second copper pad by dripping or spraying to form a first copper-phenyl compound layer on the surface of the first copper pad and a second copper-phenyl compound layer on the surface of the second copper pad.

7. The method as described in claim 6, wherein during the formation of the first copper pad or the second copper pad, a metal layer is first filled, followed by a chemical mechanical polishing process, and then the phenyl antioxidant solution is coated.

8. The method as described in claim 6, wherein after forming the first copper and phenyl compound layer and the second copper and phenyl compound layer on the respective surfaces of the first copper pad and the second copper pad, the first copper pad and the second copper pad are bonded.

9. The method as described in claim 8, wherein after the first copper pad and the second copper pad are bonded, a gap is included between the first copper pad or the second copper pad and an adjacent dielectric layer.

10. The method of claim 9, wherein after the first copper pad and the second copper pad are bonded, a heating step is further included to cause the first copper pad and the second copper pad to expand and come into contact with each other for bonding.

11. The method as described in claim 10, wherein the heating step comprises heating in a hydrogen atmosphere at a temperature of 150 to 350 degrees Celsius.

12. The method as described in claim 10, wherein after the heating step, the first copper pad and the second copper pad expand and fill the gap between the first copper pad or the second copper pad and the dielectric layer.

13. The method as claimed in claim 10, wherein during the heating step, in the portion where the first copper pad and the second copper pad overlap, the compound layer of the first copper and the phenyl compound and the compound layer of the second copper and the phenyl compound shrink, and the first copper pad and the second copper pad expand and break through the compound layer of the first copper and the phenyl compound and the compound layer of the second copper and the phenyl compound.

14. The method as described in claim 5, wherein the phenyl antioxidant solution comprises benzotriazole or diphenyl disulfide.

15. The method as claimed in claim 6, wherein the first copper and phenyl compound layer and the second copper and phenyl compound layer comprise: a copper and benzotriazole compound layer, or a copper and diphenyl disulfide compound layer.

16. The method as described in claim 5, wherein after the first copper pad and the second copper pad are bonded, the resistance of the interface is less than 0.025 ohms.

17. The method as described in claim 6, wherein the thickness of the first copper and phenyl compound layer and the second copper and phenyl compound layer is between 10 and 400 angstroms.

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