Method of manufacturing of advanced three-dimensional semiconductor structures and structures produced therefrom
A method of interconnecting metallic structures in the manufacture of a three-dimensional semiconductor is provided, the method comprising providing a first upper surface of a first substrate and a second upper surface of a second substrate with a bonding layer; bonding the first upper surface to the second upper surface to provide a bond; etching a via through a lower surface of the first substrate, through the first substrate, around a first metallic structure embedded in the first substrate, through the bond and to a second metallic structure embedded in the second substrate; and filling the via with a conductive material to provide a via structure, thereby electrically connecting the metallic structures.
1. A method of interconnecting metallic structures in the manufacture of a three-dimensional semiconductor structure, the method comprising providing a first upper surface of a first substrate and a second upper surface of a second substrate with a bonding layer; bonding the first upper surface to the second upper surface to provide a bond; etching a via through a lower surface of the first substrate, through the first substrate, adjacent to and in contact with a first metallic structure embedded in the first substrate, through the bond and to a second metallic structure embedded in the second substrate; and filling the via with a conductive material to provide a via structure, thereby electrically connecting the metallic structures.
2. The method of claim 1 , further comprising an etch stop in the first metallic structure protecting a conductive layer in the first metallic structure from being etched.
3. The method of claim 2 , further comprising an etch stop in the second metallic structure.
4. The method of claim 3 , wherein the etching provides a via of less than about 500 nanometres in diameter.
5. The method of claim 4 , further comprising bonding a third substrate to the lower surface of the first substrate to provide a second bond.
6. The method of claim 5 , further comprising etching a second via through the third substrate, adjacent to and in contact with a third metallic structure embedded in the third substrate, and through the second bond to the via structure.
7. The method of claim 6 , further comprising filling the second via with a conductive material to extend the via structure, thereby electrically connecting the metallic structures.
8. The method of claim 7 , further comprising, in order, bonding, etching a via and filling the via in a fourth and subsequent substrates, thereby providing a three-dimensional semiconductor structure of n substrates, where n is the total number of substrates.
9. The method of any one of claims 2 to 8 , wherein the method is conducted at room temperature.
10. The method of claim 9 , wherein the bonding is oxide bonding.
11. A method of connecting substrates in the manufacture of a three-dimensional semiconductor structure, the method comprising: selecting a first substrate with a first upper surface and a first metallic structure below the first upper bottom; selecting a second substrate with a second upper surface and a second metallic structure below the second upper surface, the first metallic structure comprising a conductive layer proximate the first upper surface and an etching stop distal to the first upper surface and a second metallic structure comprising a conductive layer distal to the second upper surface and an etching stop proximate the second upper surface; providing the first upper surface and the second upper surface with a bonding layer; bonding the bonding layers to provide a bond; etching a via through a lower surface of the first substrate, through the first substrate, adjacent to and in contact with the first metallic structure, through the bond and to the second metallic structure; and filling the via with a conductive material to provide a via structure.
12. The method of claim 11 , wherein the etching produces vias of less than about 750 nm in diameter.
13. The method of claim 12 , wherein the etching produces vias of less than about 250 nm in diameter.
14. The method of claim 13 , further comprising bonding a third substrate to the lower surface of the first substrate to provide a second bond.
15. The method of claim 14 , further comprising etching a second via through the third substrate, adjacent to and in contact with a third metallic structure embedded in the third substrate, and through the second bond to the via structure.
16. The method of claim 15 , further comprising filling the second via with a conductive material to extend the via structure, thereby electrically connecting the metallic structures.
17. The method of any one of claims 10 to 16 , further comprising etching a plurality of vias in each of the substrates and filling the plurality of vias with the conductive material.
18. The method of claim 17 , wherein the etching produces the plurality of vias at a concentration of about one via per microelectronic element.
19. A method of forming a three-dimensional semiconductor structure, the method comprising: selecting a first silicon wafer which includes a first device layer and a back-end-of-line (BEOL) layer, the BEOL layer including a first upper surface and a first metal stack, the first metal stack including a conductive layer proximate the first upper surface and an etching stop distal to the first upper surface, the first upper surface provided with an oxide layer; selecting a transfer layer which includes a second device layer and a second BEOL layer, the second BEOL layer including a second upper surface and a second metal stack, the second metal stack including a conductive layer proximate the second upper surface and an etching stop distal to the second upper surface, the second upper surface provided with an oxide layer; bonding the first silicon wafer to the transfer layer with the oxide layers, such that the first upper surface faces the second upper surface; etching a plurality of vias through the transfer layer into the first BEOL layer to a depth of the first metal stack; filling the vias with a conductive material, which facilitates an electrical connection between the first and the second metal stacks, thereby forming a three-dimensional semiconductor structure.
20. The method of claim 19 , wherein the first silicon wafer is selected to have the first metal stack about 5 nm from the first upper surface and the transfer layer is selected to have the second metal stack about 5 nm from the second upper surface.
21. The method of claim 19 or 20 , further comprising etching a plurality of vias in the substrates and filling the plurality of vias with the conductive material.
22. The method of claim 21 , wherein the etching produces the plurality of vias at a concentration of about one via per microelectronic element.
23. The method of claim 22 , wherein the etching produces vias of less than about 250 nanometres in diameter.