US Patent 9818690 Self-aligned interconnection structure and method

The present disclosure provides a method that includes providing a substrate having a first dielectric material layer and first conductive features that are laterally separated from each other by segments of the first dielectric material layer; depositing a first etch stop layer on the first dielectric material layer and the first conductive features, thereby forming the first etch stop layer having oxygen-rich portions self-aligned with the segments of the first dielectric material layer and oxygen-poor portions self-aligned with the first conductive features; performing a selective removal process to selectively remove the oxygen-poor portions of the first etch stop layer; forming a second etch stop layer on the first conductive features and the oxygen-rich portions of the first etch stop layer; forming a second dielectric material layer on the second etch stop layer; and forming a conductive structure in the second dielectric material layer.