Semiconductor structure and method for forming same

1. A semiconductor structure, comprising:

a first substrate, a first opening being provided on a surface of the first substrate; and

a first bonding structure, positioned in the first opening, wherein the first bonding structure comprises a first metal layer and a second metal layer with a melting point lower than that of the first metal layer, the first metal layer comprises a first surface in contact with a bottom surface of the first opening and a second surface opposite to the first surface, the second surface is provided with a first groove, an area, not occupied by the first metal layer and the first groove, of the first opening constitutes a second groove, a third groove below the first groove, a projection of the first groove on the first surface falls within a projection of the third groove on the first surface, a projection of the second groove on the first surface coincides with the projection of the third groove on the first surface; the second metal layer is formed in the first groove, the second groove and the third groove, and a surface, exposed from the second groove, of the second metal layer constitutes a bonding surface of the first bonding structure.

2. The semiconductor structure of claim 1 , further comprising:

a first conductive via hole positioned in the first substrate, wherein the first conductive via hole is connected to the first bonding structure, and a projection of the first conductive via hole and a projection of the first groove on the first surface in a direction perpendicular to the first surface coincide.

3. The semiconductor structure of claim 1 , wherein

the first metal layer comprises at least one of copper or tungsten, and the second metal layer comprises at least one of bismuth, cadmium, tin, lead, dysprosium, and indium.

4. The semiconductor structure of claim 1 , wherein

a shape of the bonding surface of the first bonding structure comprises circular, oval, or rectangular ones.

5. The semiconductor structure of claim 1 , wherein

an opening shape of the first groove comprises circular or rectangular ones; and an outer contour shape of the second surface of the first metal layer comprises circular or rectangular ones.

6. The semiconductor structure of claim 1 , further comprising:

a second substrate, a second opening being provided on a surface of the second substrate; and

a second bonding structure, positioned in the second opening and used for bonding and connecting with the first bonding structure.

7. The semiconductor structure of claim 6 , wherein

the second bonding structure comprises a third metal layer, and a material of the third metal layer is a same as that of the first metal layer, wherein the third metal layer comprises a third surface in contact with a bottom surface of the second opening and a fourth surface opposite to the third surface.

8. The semiconductor structure of claim 7 , wherein

the fourth surface of the third metal layer constitutes a bonding surface of the second bonding structure, the fourth surface of the third metal layer has a concave shape and is bonded and connected with the bonding surface of the first bonding structure.

9. The semiconductor structure of claim 7 , wherein

the second bonding structure further comprises a fourth metal layer, a material of the fourth metal layer is a same as that of the second metal layer; and

the fourth surface of the third metal layer is provided with a fourth groove, an area, not occupied by the third metal layer and the fourth groove, of the second opening constitutes a fifth groove, the fourth metal layer is positioned in the fourth groove and the fifth groove, and a surface, exposed from the fifth groove, of the fourth metal layer constitutes a bonding surface of the second bonding structure.

10. The semiconductor structure of claim 9 , wherein

the bonding surface of the first bonding structure and the bonding surface of the second bonding structure have a same shape and area.

11. The semiconductor structure of claim 9 , wherein

the fourth metal layer does not completely fill the fifth groove, and a distance between a surface, exposed from the fifth groove, of the fourth metal layer and the surface of the second substrate is 1 nm-5 nm.

12. A method for forming a semiconductor structure, comprising:

providing a first substrate, a first opening being formed on a surface of the first substrate; and

forming a first bonding structure in the first opening, the first bonding structure comprising a first metal layer and a second metal layer with a melting point lower than that of the first metal layer; wherein said forming the first bonding structure comprises: forming the first metal layer in the first opening, the first metal layer comprising a first surface in contact with a bottom surface of the first opening and a second surface opposite to the first surface; forming a first groove on the second surface, an area, not occupied by the first metal layer and the first groove, of the first opening constituting a second groove; forming a third groove below the first groove of the first metal layer, wherein a projection of the first groove on the first surface falls within a projection of the third groove on the first surface, a projection of the second groove on the first surface coincides with the projection of the third groove on the first surface; and forming the second metal layer in the first groove, the second groove and the third groove, a surface, exposed from the second groove, of the second metal layer constituting a bonding surface of the first bonding structure.

13. The method for forming a semiconductor structure of claim 12 , further comprising:

forming a first conductive via hole in the first substrate, wherein a projection of the first conductive via hole and a projection of the first groove on the first surface in a direction perpendicular to the first surface coincide.

14. The method for forming a semiconductor structure of claim 12 , further comprising:

providing a second substrate, a second opening being formed on a surface of the second substrate;

forming a second bonding structure in the second opening;

and bonding and connecting the second bonding structure with the first bonding structure.

15. The method for forming a semiconductor structure of claim 14 , wherein

said forming the second bonding structure comprises: forming a third metal layer, wherein a material of the third metal layer is the same as that of the first metal layer, and the third metal layer comprises a third surface in contact with a bottom surface of the second opening and a fourth surface opposite to the third surface.

16. The method for forming a semiconductor structure of claim 15 , wherein

said forming the second bonding structure further comprises: forming a fourth groove on the fourth surface of the third metal layer, an area, not occupied by the third metal layer and the fourth groove, of the second opening constituting a fifth groove; forming a fourth metal layer in the fourth groove and the fifth groove, wherein a material of the fourth metal layer is the same as that of the second metal layer; and a surface, exposed from the fifth groove, of the fourth metal layer constituting a bonding surface of the second bonding structure.