CMP of copper/ruthenium substrates
View Patent ↗The invention provides a method of chemically-mechanically polishing a substrate. A substrate comprising ruthenium and copper is contacted with a chemical-mechanical polishing system comprising a polishing component, hydrogen peroxide, an organic acid, at least one heterocyclic compound comprising at least one nitrogen atom, and water. The polishing component is moved relative to the substrate, and at least a portion of the substrate is abraded to polish the substrate. The pH of the polishing system is about 6 to about 12, the ruthenium and copper are in electrical contact, and the difference between the open circuit potential of copper and the open circuit potential of ruthenium in the polishing system is about 50 mV or less.
1. A method of chemically-mechanically polishing a substrate, which method comprises:
(i) contacting a substrate comprising at least one layer of ruthenium and at least one layer of copper with a polishing pad and a chemical-mechanical polishing composition comprising:
(a) an abrasive consisting of α-alumina treated with a negatively-charged polymer or copolymer,
(b) hydrogen peroxide,
(c) an organic acid,
(d) at least one heterocyclic compound, wherein the at least one heterocyclic compound comprises at least one nitrogen atom,
(e) a phosphonic acid, and
(f) water,
(ii) moving the polishing pad relative to the substrate, and
(iii) abrading at least a portion of the substrate to polish the substrate,
wherein the pH of the water and any components dissolved or suspended therein is about 6 to about 12, wherein the at least one layer of ruthenium and at least one layer of copper are in electrical contact and are in contact with the polishing composition, wherein the difference between the open circuit potential of copper and the open circuit potential of ruthenium in the water and any components dissolved or suspended therein is about 50 mV or less, and wherein a selectivity for polishing copper as compared to ruthenium is about 2 or less.
2. The method of claim 1 , wherein the polishing composition comprises about 0.01 wt. % to about 5 wt. % of abrasive.
3. The method of claim 1 , wherein the negatively-charged polymer or copolymer is selected from the group consisting of poly(2-acrylamido-2-methyipropane sulfonic acid) and polystyrenesulfonic acid.
4. The method of claim 1 , wherein the polishing composition comprises about 0.1 wt. % to about 5 wt. % of hydrogen peroxide.
5. The method of claim 1 , wherein the organic acid is selected from the group consisting of malonic acid, succinic acid, adipic acid, lactic acid, malic acid, citric acid, glycine, aspartic acid, tartaric acid, gluconic acid, iminodiacetic acid, and fumaric acid.
6. The method of claim 5 , wherein the organic acid is tartaric acid.
7. The method of claim 1 , wherein the polishing composition comprises at least one heterocyclic compound selected from the group consisting of 1,2,3-triazole, 1,2,4-triazole, benzotriazole, benzimidazole, benzothiazole, and combinations thereof.
8. The method of claim 7 , wherein the polishing composition comprises benzotriazole.
9. The method of claim 8 , wherein the polishing composition comprises about 0.005 wt. % to about 0.1 wt. % of benzotriazole.
10. The method of claim 8 , wherein the polishing composition further comprises 1,2,4-triazole.
11. The method of claim 1 , wherein the polishing composition further comprises a dispersing agent.
12. The method of claim 11 , wherein the dispersing agent is polyacrylic acid.
13. The method of claim 1 , wherein the phosphonic acid is selected from the group consisting of 1-hydroxyethylidene-1,1-diphosphonic acid, aminotris(methylenephosphonic acid), N-carboxymethylaminomethanephosphonic acid, 1-hydroxyethane-1,1-diphosphonic acid, dialkyl phosphonates, dialkyl alkylphosphonates, and mixtures thereof.
14. The method of claim 1 , wherein the polishing composition further comprises a diamine compound comprising an ether group.
15. The method of claim 14 , wherein the diamine compound comprising an ether group is a polyether diamine.
16. The method of claim 1 , wherein the substrate further comprises at least one layer of tantalum.
17. The method of claim 16 , wherein the substrate comprises at least one layer of ruthenium disposed between the at least one tantalum layer and the at least one copper layer.
18. The method of claim 16 , wherein the substrate further comprises a material that is not copper or ruthenium, and selectivity for polishing either copper or ruthenium as compared to the material that does not comprise copper or ruthenium is about 2 or less.
19. The method of claim 1 , wherein the pH is about 7 to about 9.