Interconnect structure with improved dielectric line to via electromigration resistant interfacial layer and method of fabricating same

Abstract

Interconnect structures having improved electromigration resistance are provided that include a metallic interfacial layer (or metal alloy layer) that is present at the bottom of a via opening. The via opening is located within a second dielectric material that is located atop a first dielectric material that includes a first conductive material embedded therein. The metallic interfacial layer (or metal alloy layer) that is present at the bottom of the via opening is located between the underlying first conductive material embedded within the first dielectric and the second conductive material that is embedded within the second dielectric material. Methods of fabricating the improved electromigration resistance interconnect structures are also provided.

1 . An interconnect structure comprising:
 a first dielectric material having a first conductive material embedded therein;   a second dielectric material located atop the first dielectric material, said second dielectric material includes at least one conductively filled opening comprising a combined via and line that is located above said first conductive material; and   an interfacial layer located only at a bottom portion of said via and at a bottom horizontal portion of said line, wherein said interfacial layer present at the bottom portion of the via separates the first conductive material embedded within the first dielectric material from said at least one conductively filled opening within the second dielectric material, said interfacial layer located within the bottom portion of said via comprises at least one of a metallic interfacial layer and a metal alloy interfacial layer, and said interfacial layer located within the bottom horizontal portion of said line is a metallic interfacial layer.   
     
     
         2 . The interconnect structure of  claim 1  wherein said metallic interfacial layer comprises a conductive metal including metals from Group VB or VIII of the Periodic Table of Elements. 
     
     
         3 . The interconnect structure of  claim 1  wherein said metal alloy interfacial layer comprises Ta—Cu, Ru—Cu, Co—Cu or Ir—Cu. 
     
     
         4 . The interconnect structure of  claim 1  wherein said first conductive material and said at least one conductively filled opening both include Cu or a Cu alloy. 
     
     
         5 . The interconnect structure of  claim 1  wherein said first and second dielectric materials are composed of a same or different dielectric material, said dielectric material having a dielectric constant of about 4.0 or less. 
     
     
         6 . The interconnect structure of  claim 1  further comprising a dielectric capping layer present between said first and second dielectric materials. 
     
     
         7 . The interconnect structure of  claim 1  wherein said interfacial layer at the bottom of the via is a metallic interfacial layer. 
     
     
         8 . An interconnect structure comprising:
 a first dielectric material having a first conductive material embedded therein; and   a second dielectric material located atop the first dielectric material, said second dielectric material includes at least one conductively filled opening that is located above said first conductive material, wherein said at least one conductively filled opening and said first conductive material are horizontally separated by a metal alloy interfacial layer that is present only within a bottom portion of said at least one conductively filled opening, said metal alloy interfacial layer comprising a reaction product of a metallic interfacial layer and the first conductive material.   
     
     
         9 . The interconnect structure of  claim 8  wherein said metal alloy interfacial layer comprises Ta—Cu, Ru—Cu, Co—Cu or Ir—Cu. 
     
     
         10 . The interconnect structure of  claim 8  wherein said first conductive material and said at least one conductively filled opening both include Cu or a Cu alloy. 
     
     
         11 . The interconnect structure of  claim 8  wherein said first and second dielectric materials are composed of a same or different dielectric material, said dielectric material having a dielectric constant of about 4.0 or less. 
     
     
         12 . The interconnect structure of  claim 8  further comprising a dielectric capping layer present between said first and second dielectric materials.