US Patent 7259093 Methods of forming a conductive contact through a dielectric

A dielectric is formed over a node location on a semiconductor substrate. The dielectric comprises an insulative material over the node location, an insulative polish stop layer over the insulative material, and an insulator layer over the insulative polish stop layer. A contact opening is formed into the insulator layer, the insulative polish stop layer and the insulative material to proximate the node location. A conductive material is deposited over the insulator layer and to within the contact opening. The conductive material and the insulator layer are polished to at least a portion of the insulative polish stop layer. In one implementation and prior to depositing the conductive material, at least a portion of the contact opening is widened with an etching chemistry that is selective to widen it within the insulative material to a degree greater than any widening of the contact opening within the insulative polish stop layer.