Dual damascene structure

Abstract

A dual damascene structure is described, including a substrate, a dielectric layer, a hard mask layer, a contact and a conductive line. The dielectric layer is located on the substrate, the hard mask layer is on the dielectric layer, the contact is located in the dielectric layer, and a horizontal cross-section of the contact has an asymmetrically rounded outline. The conductive line is in the hard mask layer and the dielectric layer, and is located on and electrically connected to the contact. The conductive line has a laterally swelling portion on an edge portion of the first contact, wherein the borders of the laterally swelling portion and the edge portion are contiguous.

1 . A dual damascene structure, comprising: 
 a substrate;    a dielectric layer on the substrate;    a hard mask layer on the dielectric layer;    a first contact in the dielectric layer, having a horizontal cross-section with an asymmetrically rounded outline; and    a conductive line in the hard mask layer and the dielectric layer, passing over and electrically connecting with the first contact,    wherein the conductive line has a laterally swelling portion on an edge portion of the first contact, and borders of the laterally swelling portion and the edge portion are contiguous.    
     
     
         2 . The dual damascene structure of  claim 1 , wherein the hard mask layer comprises a metal hard mask layer.  
     
     
         3 . The dual damascene structure of  claim 2 , wherein the metal hard mask layer comprises at least one material selected from the group consisting of Ti, TiN, Ta, TaN and WN.  
     
     
         4 . The dual damascene structure of  claim 1 , further comprising: 
 a second contact between the substrate and the conductive line, having a horizontal cross-section with a symmetrically rounded outline.    
     
     
         5 . The dual damascene structure of  claim 4 , wherein the first contact, the second contact and the conductive layer comprise the same conductive material.  
     
     
         6 . The dual damascene structure of  claim 5 , wherein the conductive material comprises copper (Cu).  
     
     
         7 . The dual damascene structure of  claim 1 , wherein the dielectric layer comprises a low-k material having a dielectric constant lower than 4.