Depositing ruthenium layers in interconnect metallization
In some embodiments, deposition processes for ruthenium (Ru) feature fill include deposition of a thin, protective Ru film under reducing conditions, followed by a Ru fill step under oxidizing conditions. The presence of protective Ru films formed under oxygen-free conditions or with an oxygen-removing operation can enable Ru fill without oxidation of an underlying adhesion layer or metal feature.
1. A method comprising:
receiving a substrate including a feature;
performing multiple atomic layer deposition (ALD) cycles to deposit a ruthenium (Ru) liner layer in the feature, wherein each of the ALD cycles include a dose of a reducing agent; and
after depositing the Ru liner layer, at least partially filling the feature with ruthenium by reacting a first ruthenium precursor with an oxidant to form metallic ruthenium (Ru).
2. The method of claim 1 , wherein each of the multiple ALD cycles comprises reacting a second ruthenium precursor with the reducing agent, the second ruthenium precursor being different than the first ruthenium precursor.
3. The method of claim 2 , wherein the first ruthenium precursor has an oxidation state of 0 and the second ruthenium precursor has an oxidation state of +2.
4. The method of claim 1 , wherein each of the multiple ALD cycles include reacting the first ruthenium precursor with the reducing agent.
5. The method of claim 1 , where the feature includes a first liner layer on which the Ru liner is deposited.
6. The method of claim 1 , wherein the ALD cycles are thermal ALD cycles.
7. The method of claim 1 , wherein the ALD cycles are plasma enhanced ALD (PEALD) cycles.
8. The method of claim 1 , wherein the reducing agent is H 2 or NH 3 or plasma species generated from H 2 or NH 3 .
9. The method of claim 1 , wherein the oxidant is O 2 , O 3 , or H 2 O.
10. The method of claim 1 , wherein each of the multiple ALD cycles comprises reacting the first ruthenium precursor with an oxidant.
11. The method of claim 10 , wherein the dose of the reducing agent removes oxygen incorporated into the Ru liner layer or an underlying metallic layer.
12. The method of claim 1 , wherein the feature is fully filled with ruthenium.
13. The method of claim 1 , wherein the feature is fully filled with a metal selected from Ru, Cu, W, Co, Mo, Ni, and Al.
14. The method of claim 1 , wherein each of the multiple ALD cycles comprises a ruthenium precursor dose followed by an oxidant dose.
15. The method of claim 14 , wherein the ruthenium precursor dose and oxidant dose are non-plasma doses.
16. The method of claim 15 , wherein each of the multiple ALD cycles comprises a reducing plasma dose after the oxidant dose.
17. The method of claim 16 , wherein there is no purge between oxidant dose and the reducing plasma dose.
18. The method of claim 14 , wherein the oxidant dose is a mixture of an oxidant and a reducing agent.
19. The method of claim 1 , wherein the Ru liner layer is 2 nm or less.
20. The method of claim 1 , wherein the Ru liner layer is deposited on a layer selected from tungsten carbon nitride (WCN), titanium nitride (TiN), tungsten nitride (WN), tungsten carbide (WC), and tantalum nitride (TaN).
21. The method of claim 1 , wherein the first ruthenium precursor is an organometallic precursor.
22. The method of claim 1 , wherein the first ruthenium precursor has an oxidation state of 0.
23. The method of claim 1 , wherein the first ruthenium precursor has an oxidation state of +2.
24. The method of claim 1 , wherein the first ruthenium precursor is reacted with an oxidant in an ALD process or a CVD process.
25. The method of claim 1 , wherein the Ru liner layer is oxygen-free.