Ic interconnect structures and methods for making same

Abstract

Methods and structures are disclosed for advanced interconnects in sub-micron and sub-half-micron integrated circuit devices fabricated using a single damascene process. a dielectric etch-stop layer (e.g., silicon nitride) is deposited subsequent to rather than prior to CMP processing of the previous metallization layer (e.g., the conductive plug). This scheme effectively eliminates the effect of CMP-induced erosion on the etch-stop layer and therefore allows an extremely thin etch stop to be used. Moreover, a high etch-selectivity can be obtained for the trench etch, and all etch-stop material is removed from beneath the interconnect metal, thereby reducing parasitic effects. A patterned dielectric layer is used as a metal cap in place of the standard blanket silicon nitride layer, thus preventing the formation of blisters and bubbles associated with trapped moisture and gasses, and reducing interconnect capacitance.