COMPOSITION AND METHOD FOR COBALT CMP
A chemical mechanical polishing composition for polishing a substrate having a cobalt layer includes a water based liquid carrier, cationic silica abrasive particles dispersed in the liquid carrier, and a triazole compound, wherein the polishing composition has a pH of greater than about 6 and the cationic silica abrasive particles have a zeta potential of at least 10 mV. The triazole compound is not benzotriazole or a benzotriazole compound. A method for chemical mechanical polishing a substrate including a cobalt layer includes contacting the substrate with the above described polishing composition, moving the polishing composition relative to the substrate, and abrading the substrate to remove a portion of the cobalt layer from the substrate and thereby polish the substrate.
1 . A method of chemical mechanical polishing a substrate including a cobalt layer, the method comprising:
(a) contacting the substrate with a polishing composition comprising:
(i) a water based liquid carrier;
(ii) cationic silica abrasive particles dispersed in the liquid carrier, the cationic silica abrasive particles having a zeta potential of at least 10 mV;
(iii) a triazole compound, wherein the triazole compound is a triazole pyridine compound, and wherein the triazole pyridine compound is 1H-1,2,3-Triazolo[4,5,b]pyridine, 1-Acetyl-1H-1,2,3-triazolo[4,5,b]pyridine, or a mixture thereof; and
wherein the polishing composition has a pH of greater than about 6;
(b) moving the polishing composition relative to the substrate; and
(c) abrading the substrate to remove a portion of the cobalt layer from the substrate and thereby polish the substrate.
2 . The method of claim 1 , wherein the triazole pyridine compound is 1H-1,2,3-Triazolo[4,5,b]pyridine.
3 . The method of claim 1 , wherein the polishing composition comprises from about 50 to about 500 ppm of the triazole pyridine compound.
4 . The method of claim 1 , wherein the polishing composition is substantially free of a per-compound oxidizer.
5 . The method of claim 1 , wherein the polishing composition has a pH from about 6 to about 8.
6 . The method of claim 1 , wherein the cationic silica abrasive particles have an isoelectric point greater than about 9.
7 . The method of claim 1 , wherein the cationic silica abrasive particles comprise colloidal silica particles having have a permanent positive charge of at least 20 mV at a pH of greater than about 6.
8 . The method of claim 1 , comprising less than about 2 weight percent of the cationic silica abrasive particles.
9 . The method of claim 1 , wherein the substrate further comprises a dielectric layer and wherein the abrading in (c) also removes a portion of the dielectric layer from the substrate.
10 . The method of claim 1 , wherein a removal rate of the dielectric layer in (c) is greater than a removal rate of cobalt in (c).
11 . The method of claim 10 , wherein the dielectric layer is tetraethyl orthosilicate (TEOS).