Reverse selective etch stop layer
Methods and apparatus for forming a reverse selective etch stop layer are disclosed. Some embodiments of the disclosure provide interconnects with lower resistance than methods which utilize non-selective (e.g., blanket) etch stop layers. Some embodiments of the disclosure utilize reverse selective etch stop layers within a subtractive etch scheme. Some embodiments of the disclosure selectively deposit the etch stop layer by passivating the surface of the metal material.
1. A method comprising:
selectively depositing an etch stop layer on a first dielectric material over a first metal material, the first dielectric material comprising a plurality of features formed therein with the first metal material within the plurality of features;
depositing a second metal material on the first metal material and the etch stop layer;
etching the second metal material to expose a portion of the etch stop layer; and
removing the portion of the etch stop layer exposed by etching the second metal material to expose a top surface of the first dielectric material,
wherein a top surface of the second metal material is higher than the exposed top surface of the first dielectric material.
2. The method of claim 1 , wherein the first dielectric material consists essentially of a low-k dielectric.
3. The method of claim 1 , wherein the first metal material consists essentially of copper.
4. The method of claim 1 , wherein the etch stop layer is deposited with a selectivity greater than or equal to 5.
5. The method of claim 1 , wherein the first metal material and the second metal material are the same material.
6. The method of claim 1 , wherein at least one feature of the plurality of features is a via.
7. The method of claim 1 , wherein the top surface of the first metal material is coplanar with a top surface of first dielectric material.
8. The method of claim 1 , wherein the first metal material does not completely fill the plurality of features.
9. The method of claim 8 , wherein the second metal material fills the plurality of features and is deposited on a top surface of the etch stop layer.
10. The method of claim 1 , wherein selectively depositing the etch stop layer comprises:
exposing the first metal material to a blocking compound to form a passivated surface of the first metal material; and
depositing the etch stop layer on the first dielectric material over the passivated surface of the first metal material.
11. The method of claim 10 , wherein the blocking compound comprises one or more of a phosphoric acid, alkyl silane, halogenated silane, thiol or unsaturated hydrocarbon.
12. The method of claim 10 , further comprising removing the blocking compound from the passivated surface of the first metal material before depositing the second metal material.
13. The method of claim 12 , wherein the blocking compound is removed by exposure to a plasma comprising H 2 .
14. The method of claim 1 , wherein the etch stop layer comprises tantalum nitride (TaN).
15. The method of claim 1 , wherein the method forms a conductive path between the first metal material within at least two of the plurality of features.
16. The method of claim 1 , wherein etching the second metal material comprises a photolithography process.
17. The method of claim 1 , wherein the resistance between the first metal material and the second metal material is less than the resistance of a similar device formed with a non-selective (blanket) etch stop layer.
18. A method comprising:
exposing a first dielectric material to a blocking compound, the first dielectric material comprising a plurality of features formed therein and a first metal material within the plurality of features, wherein exposing the first dielectric material to the blocking compound forms a passivated surface of the first metal material;
selectively depositing an etch stop layer on the first dielectric material over the passivated surface of the first metal material;
removing the blocking compound from the passivated surface of first metal material;
depositing a second metal material on the first metal material and the etch stop layer after removing the blocking compound from the passivated surface of first metal material;
etching the second metal material by photolithography to expose a portion of the etch stop layer and form a conductive path between the first metal material within the plurality of features; and
removing the portion of the etch stop layer exposed by etching the second metal material to expose a top surface of the first dielectric material,
wherein a top surface of the second metal material is higher than the exposed top surface of the first dielectric material.