Organic copper diffusion barrier layer

Abstract

An organic copper diffusion barrier layer having low dielectric constant is provided. The organic copper diffusion barrier layer can be applied to a dual damascene structure, which is formed between a copper wiring layer and an organic dielectric layer, to defend copper diffusion from the copper wiring layer into the organic dielectric layer. The organic copper diffusion barrier layer includes a benzocyclo polymer, which it has a benzene ring functional group that can catch copper and prevent copper diffusing into the organic dielectric layer. The problem of thermal diffusion and electro-migration can be avoided.

What is claimed is:  
     
         1 . A copper damascene structure adapted for a semiconductor substrate, comprising: 
 a first dielectric layer having an opening on the semiconductor substrate;    a first copper layer in the opening of the first dielectric layer;    an organic copper diffusion barrier layer having a benzocyclo polymer on the first copper layer and the first dielectric layer;    a second dielectric layer on the organic copper diffusion barrier layer;    a second copper layer in the second dielectric layer, wherein a portion of the second copper layer is down through the organic copper diffusion barrier layer and connected to the first copper layer.    
     
     
         2 . The structure according to  claim 1 , wherein the thickness of the organic copper diffusion barrier layer is about 300-900 angstroms.  
     
     
         3 . The structure according to  claim 1 , wherein a method of forming the organic copper diffusion barrier layer comprises spin-on coating.  
     
     
         4 . The structure according to  claim 1 , wherein the benzocyclo polymer has a benzene ring functional group that can defend the copper diffusion from the first copper layer to the second dielectric layer.  
     
     
         5 . The structure according to  claim 1 , wherein the benzocyclo polymer comprises a polymer of benzocyclobutene.  
     
     
         6 . The structure according to  claim 1 , wherein the second copper layer is composed of a copper wiring layer and a copper via plug, and the copper wiring layer is connected to the first copper layer through the copper via plug.  
     
     
         7 . A method of forming a copper damascene structure, comprising the steps of: 
 providing a semiconductor substrate;    forming a first dielectric layer with an opening over the semiconductor substrate;    forming a first copper layer in the opening of the first dielectric layer;    forming an organic copper diffusion barrier layer over the first copper layer and the first dielectric layer;    forming a second dielectric layer over the organic copper diffusion barrier layer; and    forming a second copper in the second dielectric layer, wherein a portion of the second copper layer is connected to the first copper layer through the organic copper diffusion barrier layer.    
     
     
         8 . The method according to  claim 7 , wherein forming the first copper layer in the first dielectric layer comprises the steps of: 
 forming a patterned photoresist layer on the first dielectric layer;    anisotropically etching the first dielectric layer to form a trench opening in the first dielectric layer by using the patterned photoresist layer as a mask;    removing the patterned photoresist layer; and    filling the trench opening with copper to form the first copper layer.    
     
     
         9 . The method according to  claim 7 , wherein the thickness of the organic copper diffusion barrier layer is about 300-900 angstroms.  
     
     
         10 . The method according to  claim 7 , wherein a method of forming the benzocyclo barrier comprises spin-on coating.  
     
     
         11 . The method according to  claim 7 , wherein the organic copper diffusion barrier layer has a benzocyclo polymer.  
     
     
         12 . The method according to  claim 11 , wherein the benzocyclo polymer comprising a polymer of benzocyclobutene.  
     
     
         13 . The method according to  claim 11 , wherein the benzocyclo polymer has a benzene ring functional group that can defend the copper diffusion from the first copper layer to the second dielectric layer.  
     
     
         14 . The method according to  claim 7 , wherein the second copper layer is composed of a copper wiring layer and a copper via plug, and the copper wiring layer is connected to the first copper layer through the copper via plug.  
     
     
         15 . The method according to  claim 14 , wherein forming the second copper layer comprises the steps of: 
 forming a trench opening and a via opening in the second dielectric layer, wherein the via opening is under the bottom of the trench opening and the via opening exposes the first copper layer in the bottom; and    filling the via opening and the trench opening with copper to form the copper via plug and the copper wiring layer, respectively.    
     
     
         16 . An organic copper diffusion barrier layer forming on a copper layer, and a dielectric layer forming thereon, the organic copper diffusion barrier layer comprises: 
 a benzocyclo polymer having a benzocyclo funcional group that can defend copper diffusion from the copper layer to the dielectric layer.    
     
     
         17 . The organic copper diffusion barrier layer according to  claim 16 , wherein the benzocyclo polymer comprises a polymer of benzocyclobutene.  
     
     
         18 . The organic copper diffusion barrier layer according to  claim 16 , wherein the organic copper diffusion barrier layer has a thickness of about  300 - 900  angstroms.