Chemical mechanical planarization solution for removal of tantalum barrier material. The solution comprises 0 to 25 weight percent of an oxidizing agent, 0 to 15 weight percent of a non-ferrous metal inhibitor and 0 to 20 weight percent of a complexing agent of the non-ferrous metal, 0.01 to 12 weight percent selected from formamidine, formamidine Salts, formamidine derivatives, guanidine derivatives, tantalum removers of guanidinium salts and mixtures thereof, 0 to 5 weight percent abrasives, 0 to 15 weight percent total particles selected from polymer particles and polymer coated particles , and the balance is water. The solution has a selectivity of tantalum nitride to TEOS of at least 3 to 1 as measured using a microporous polyurethane polishing pad pressure perpendicular to the wafer of less than 20.7 KPa.
Typically, a semiconductor wafer has a silicon wafer and a dielectric layer comprising a plurality of trenches arranged within the dielectric layer to form a circuit interconnection pattern. The arrangement of these patterns usually has a damascene structure or a dual damascene structure. The patterned dielectric layer is covered with a barrier layer and the barrier layer is covered with a metal layer. The metal layer has at least a sufficient thickness to fill the patterned trenches with metal to form circuit interconnections.
The barrier layer is typically a metal, metal alloy or intermetallic compound, such as tantalum or tantalum nitride. The barrier layer forms a layer that prevents migration and diffusion between layers within the wafer. For example, a barrier layer can prevent interconnect metals such as copper or silver from diffusing into adjacent dielectrics. The barrier layer material must be resistant to most acids and thus resistant to dissolution by the fluid polishing composition used for CMP. In addition, these barrier layers exhibit some toughness against abrasive removal of abrasive particles and fixed mask pads in CMP slurries.
A chemical mechanical planarization method for removing tantalum barrier material from a semiconductor wafer, the method comprising contacting a wafer substrate comprising a tantalum barrier material and a dielectric with a polishing solution selected from the group consisting of Tantalum reagents of amidines, formamidine salts, formamidine derivatives, guanidine derivatives, guanidine salts, and mixtures thereof; and polishing the wafer substrate using a polishing pad to remove the tantalum barrier from the wafer substrate at a removal rate layer material, the removal rate is greater than that for the dielectric and is expressed in angstroms per minute.
