Integrated circuit interconnect structure having discontinuous barrier layer and air gap

Abstract

A method includes providing a substrate, a dielectric layer over the substrate, and metallic features over the dielectric layer; and forming an organic blocking layer (OBL) over the dielectric layer and between lower portions of the metallic features. The OBL covers sidewall surfaces of the lower portions, but not upper portions, of the metallic features. The method further includes depositing a dielectric barrier layer over top surfaces of the metallic features and over the sidewall surfaces of the upper portions of the metallic features, wherein at least a portion of a top surface of the OBL is not covered by the dielectric barrier layer; forming an inter-metal dielectric (IMD) layer between the metallic features and above the OBL; and removing the OBL, leaving an air gap above the dielectric layer, below the dielectric barrier layer and the IMD layer, and laterally between the lower portions of the metallic features.