Interconnection structure and method of forming the same

Abstract

After a copper interconnection is formed above a substrate, a surface of the copper interconnection is activated by performing acid cleaning. Thereafter, the substrate is immersed in a BTA (Benzo triazole) aqueous solution to form a protection film covering the surface of the copper interconnection. At this time, Cu—N—R bonds (R is an organic group) are formed in grain boundary portions in the surface of the copper interconnection. Thereafter, the protection film is removed by performing alkaline cleaning. The Cu—N—R bonds remain in the grain boundary portions in the surface of the copper interconnection even after the protection film is removed. Subsequently, the surface of the copper interconnection is subjected to an activation process, and a barrier layer is formed thereafter by electroless-plating the surface of the copper interconnection with NiP or CoWP.

1 . An interconnection structure comprising:
 a substrate;   a copper interconnection formed above the substrate;   an insulating layer covering the copper interconnection; and   a barrier layer formed between the copper interconnection and the insulating layer,   wherein the interconnection structure has a Cu—N—R bond (provided that R is an organic group) in a portion of a grain boundary in a surface of the copper interconnection.   
     
     
         2 . The interconnection structure according to  claim 1 , wherein an underlying insulating film and an adhesion layer are provided between the substrate and the copper interconnection, the adhesion layer securing an adhesion between the underlying insulating film and the copper interconnection. 
     
     
         3 . The interconnection structure according to  claim 1 , wherein the barrier layer contains one metal compound selected from a group consisting of CoWP, CoWB, CoP, CoB, NiP, NiWP, NiB, and NiWB, as a main component. 
     
     
         4 . A method of forming an interconnection structure, the method comprising:
 forming a copper interconnection above a substrate;   forming a Cu—N—R bond (provided that R is an organic group) in a grain boundary portion in a surface of the copper interconnection by bringing the copper interconnection into contact with an organic compound;   cleaning the surface of the copper interconnection by using a cleaning solution;   forming a barrier layer by depositing a metal onto the surface of the copper interconnection after cleaning; and   forming an insulating film covering the copper interconnection and the barrier layer above the substrate.   
     
     
         5 . The method of forming an interconnection structure according to  claim 4 , wherein the organic compound is any of imidazole-based organic compounds and organic compounds having a benzene ring and a N—H bond. 
     
     
         6 . The method of forming an interconnection structure according to  claim 4 , wherein a pH of the cleaning solution is within a range of 8.0 to 10.0. 
     
     
         7 . The method of forming an interconnection structure according to  claim 4 , wherein the barrier layer is formed by electroless plating. 
     
     
         8 . The method of forming an interconnection structure according to  claim 4 , wherein the barrier layer contains one metal compound selected from a group consisting of CoWP, CoWB, CoP, CoB, NiP, NiWP, NiB, and NiWB, as a main component. 
     
     
         9 . The method of forming an interconnection structure according to  claim 4 , wherein the forming a Cu—N—R bond and the cleaning the surface of the copper interconnection are performed simultaneously by using a BTA (Benzo triazole) aqueous solution having a pH adjusted to be within a range of 8.0 to 10.0. 
     
     
         10 . The method of forming an interconnection structure according to  claim 4 , wherein the copper interconnection is formed by a semi-additive method. 
     
     
         11 . The method forming an interconnection structure according to  claim 4 , wherein,
 before the forming the copper interconnection, the method comprises:
 forming a underlying insulating film on the substrate; and 
 forming an adhesion layer made of a metal on the underlying insulating film, and, 
   between the forming a copper interconnection and the forming a Cu—N—R bond, the method comprises:
 removing a portion of the adhesion layer, the portion not covered with the copper interconnection.