Damascene interconnection structure and dual damascene process thereof

Abstract

A dual damascene structure is disclosed. The dual damascene structure includes: a substrate comprising thereon a base dielectric layer and a lower wiring layer inlaid in the base dielectric layer; a dielectric layer on the substrate; a via opening in the dielectric layer, wherein the via opening misaligns with the lower wiring layer thus exposing a portion of the lower wiring layer and a portion of the base dielectric layer, wherein the via opening comprises a bottom including a recessed area; a barrier layer lining interior surface of the via opening and covers the exposed lower wiring layer and the base dielectric layer, wherein only the barrier layer fills the recessed area; and a copper layer filling the via opening on the barrier layer.

What is claimed is: 
     
         1 . A dual damascene structure, comprising:
 a substrate comprising thereon a base dielectric layer and a lower wiring layer inlaid in the base dielectric layer;   a dielectric layer on the substrate;   a via opening in the dielectric layer, wherein the via opening misaligns with the lower wiring layer thus exposing a portion of the lower wiring layer and a portion of the base dielectric layer, wherein the via opening comprises a bottom including a recessed area;   a barrier layer lining interior surface of the via opening and covers the exposed lower wiring layer and the base dielectric layer, wherein only the barrier layer fills the recessed area; and   a copper layer filling the via opening on the barrier layer.   
     
     
         2 . The dual damascene structure of  claim 1  wherein the base dielectric layer comprises organosilicate glass. 
     
     
         3 . The dual damascene structure of  claim 1  wherein the base dielectric layer comprises C, H-doped silicon oxide dielectric. 
     
     
         4 . The dual damascene structure of  claim 1  wherein the dielectric layer has a dielectric constant that is less than 3. 
     
     
         5 . The dual damascene structure of  claim 1  wherein a step height between the recessed area and a top surface of the lower wiring layer is less than 150 angstroms. 
     
     
         6 . The dual damascene structure of  claim 1  wherein a step height between the recessed area and a top surface of the lower wiring layer is less than 50 angstroms. 
     
     
         7 . The dual damascene structure of  claim 1  further comprising a cap layer capping the lower wiring layer and the base dielectric layer. 
     
     
         8 . The dual damascene structure of  claim 7  wherein the cap layer comprises nitrogen doped silicon carbide (SiCN). 
     
     
         9 . The dual damascene structure of  claim 7  wherein the cap layer comprises SiCN, SiN, SiON, SiC, or SiCO. 
     
     
         10 . The dual damascene structure of  claim 7  wherein the cap layer has a thickness of 300-800 angstroms.