Compositions and methods for CMP of indium tin oxide surfaces
The present invention provides chemical-mechanical polishing (CMP) compositions and methods for polishing an ITO surface. The compositions of the invention comprise a particulate zirconium oxide or colloidal silica abrasive, which has a mean particle size of not more than about 150 nm, suspended in an aqueous carrier, which preferably has a pH of not more than about 5. Preferably, the abrasive has a surface area in the range of about 40 to about 220 m 2 /g. The CMP compositions of the invention provide an acceptably low surface roughness when used to polish an ITO surface, providing clean and uniform surfaces.
1 . A chemical-mechanical polishing (CMP) composition for polishing an indium tin oxide (ITO) surface, the composition comprising a particulate zirconium oxide or colloidal silica abrasive having a particle size of not more than about 150 nm, dispersed in an aqueous carrier.
2 . The CMP composition of claim 1 wherein the abrasive is present in the composition in an amount in the range of about 0.1 to about 10 percent by weight.
3 . The CMP composition of claim 1 wherein the abrasive has a surface area in the range of about 40 to about 220 m 2 /g.
4 . The CMP composition of claim 1 wherein the aqueous carrier has a pH of not more than about 5.
5 . A chemical-mechanical polishing (CMP) method for polishing an indium tin oxide (ITO) surface, the method comprising the steps of:
(a) contacting the ITO surface with a polishing pad and an aqueous CMP composition of claim 1 , and
(b) causing relative motion between the polishing pad and the ITO surface while maintaining a portion of the CMP composition in contact with the ITO surface between the pad and the substrate for a time period sufficient to abrade at least a portion of the ITO from the surface.
6 . A chemical-mechanical polishing (CMP) composition for polishing an indium tin oxide (ITO) surface, the composition comprising a particulate zirconium oxide abrasive having a particle size of not more than about 150 nm and a surface area in the range of about 40 to about 75 cm 2 /g, dispersed in an aqueous carrier.
7 . The CMP composition of claim 6 wherein the abrasive is present in the composition in an amount in the range of about 0.1 to about 10 percent by weight.
8 . The CMP composition of claim 6 wherein the aqueous carrier has a pH of not more than about 5.
9 . A chemical-mechanical polishing (CMP) method for polishing an indium tin oxide (ITO) surface, the method comprising the steps of:
(a) contacting the ITO surface with a polishing pad and an aqueous CMP composition of claim 6 , and
(b) causing relative motion between the polishing pad and the ITO surface while maintaining a portion of the CMP composition in contact with the ITO surface between the pad and the substrate for a time period sufficient to abrade at least a portion of the ITO from the surface.
10 . A chemical-mechanical polishing (CMP) composition for polishing an indium tin oxide (ITO) surface, the composition comprising a particulate colloidal silica abrasive having a particle size in the range of about 20 to about 140 nm dispersed in an aqueous carrier.
11 . The CMP composition of claim 10 wherein the abrasive is present in the composition in an amount in the range of about 0.1 to about 10 percent by weight.
12 . The CMP composition of claim 10 wherein the aqueous carrier has a pH of not more than about 5.
13 . The CMP composition of claim 10 wherein the abrasive has a surface area in the range of about 80 to about 220 m 2 /g.
14 . A chemical-mechanical polishing (CMP) method for polishing an indium tin oxide (ITO) surface, the method comprising the steps of:
(a) contacting the ITO surface with a polishing pad and an aqueous CMP composition of claim 10 , and
(b) causing relative motion between the polishing pad and the ITO surface while maintaining a portion of the CMP composition in contact with the ITO surface between the pad and the substrate for a time period sufficient to abrade at least a portion of the ITO from the surface.