Patent ID: 7045454

Claim:
A method of forming a dielectric layer of a first thickness on a semiconductor wafer comprising: forming the dielectric layer of the first thickness on the wafer; positioning a shield layer formed of a dielectric antireflective coating (DARC) material that is different than the dielectric layer on the dielectric layer; positioning a sacrificial layer on the shield layer; forming an aperture in the sacrificial layer, shield layer, and dielectric layer; depositing conductive material so as to fill the aperture and so as to be directly in contact with at least a portion of the sacrificial layer; removing the conductive material and the sacrificial layer using a chemical mechanical polishing process that removes the conductive material and the sacrificial layer until the shield layer is reached, wherein the shield layer is more resistant to planarization by the chemical mechanical polishing process than the sacrificial layer, and wherein the shield layer inhibits thinning of the dielectric layer during the chemical mechanical polishing process, and wherein interposing the sacrificial layer between the conductive material and the shield layer reduces the amount of conductive material on the shield layer following the chemical mechanical polishing process; and detecting when the chemical mechanical polishing process has removed the sacrificial layer by detecting when the CMP process has reached the shield layer and halting the chemical mechanical polishing process upon detecting when the sacrificial layer has been removed and prior to the complete removal of the shield layer so as to maintain the dielectric layer at the first thickness.