Apparatus for integrating low dielectric constant materials into a multilevel metallization and interconnect structure

Abstract

A method and apparatus for protecting a metal interconnect from corrosion due to contact with a low k dielectric material in a multilevel metallization and interconnect structure. To facilitate such protection, a barrier material, in the form of a sidewall spacer, is deposited between the dielectric material and the metal line.

What is claimed is:  
     
         1 . A method of forming a multilevel metallization and interconnect structure comprising the steps of: 
 forming a metal line upon a surface of a substrate, where said metal line has a top surface and sidewalls;    depositing a barrier layer over the metal line and said surface of said substrate;    removing a portion of the barrier layer where said barrier layer remains deposited on at least said sidewalls of said metal line;    depositing a first insulative layer over said metal line, said surface of said substrate and said barrier layer, where said insulative layer is a material that, but for the barrier layer protecting the sidewalls of the metal line, would react with a material of said metal line; and    forming a via that contacts a top surface of said metal line.    
     
     
         2 . The method of  claim 1  wherein the forming step further comprises the steps of: 
 etching back the first insulative layer until a surface of the first insulative layer is below the top surface of the metal line;  
 depositing a second insulative layer over the first insulative layer and planarizing the second insulative layer;  
 etching said via into said second insulative layer to expose said top surface of said metal line; and  
 depositing a conductive material into said via.  
 
     
     
         3 . The method of  claim 1  wherein the forming step further comprises the steps of: 
 depositing a second insulative layer over said first insulative layer and planarizing the second insulative layer;  
 etching a via through said first and second insulative layers to contact the top surface of the metal line; and  
 depositing a conductive liner within said via, where a material of said conductive liner is inert with respect to the material of the first insulative layer.  
 
     
     
         4 . The method of  claim 1  wherein said removing step does not remove all of the barrier layer from the top surface of the metal line.  
     
     
         5 . The method of  claim 1  wherein said material of said first insulative layer has a dielectric constant that is less than or equal to 3.8.  
     
     
         6 . The method of  claim 1  wherein said material of said first insulative layer contains fluorine.  
     
     
         7 . The method of  claim 2  wherein said metal line further comprises: 
 a layer of titanium;  
 a first layer of titanium-nitride;  
 a layer of aluminum or an aluminum-copper alloy; and  
 a second layer of titanium-nitride.  
 
     
     
         8 . The method of  claim 2  wherein said metal line further comprises: 
 a first layer of tantalum or tantalum-nitride;  
 a layer of copper or copper alloy; and  
 a second layer of tantalum or tantalum-nitride.  
 
     
     
         9 . The method of  claim 3  wherein said metal line further comprises: 
 a first layer of titanium/titanium-nitride;  
 a layer of aluminum or an aluminum-copper alloy; and  
 a second layer of titanium/titanium-nitride.  
 
     
     
         10 . The method of  claim 3  wherein said liner layer is fabricated of titanium-nitride.  
     
     
         11 . The method of  claim 1  wherein the barrier layer is fabricated of a material that impedes corrosion of the metal line by the first insulative layer.  
     
     
         12 . The method of  claim 1  wherein the barrier layer is fabricated of a material selected from one or more of the following materials: silicon nitride, silicon oxynitride, and silicon dioxide.  
     
     
         13 . The method of  claim 1  wherein the barrier layer has a thickness of less than 500 Å.  
     
     
         14 . Apparatus comprising: 
 a substrate;    a metal line formed upon said substrate, where said metal line has a top surface and sidewalls;    a barrier layer affixed to said sidewalls of said metal line;    an insulative layer, separated from said metal line by said barrier layer, where said insulative layer is fabricated of a material that, but for the barrier layer, would react with a material of the metal line.    
     
     
         15 . The apparatus of  claim 14  wherein said material of said insulative layer has a dielectric constant that is less than or equal to 3.8.  
     
     
         16 . The apparatus of  claim 14  wherein said material of said insulative layer contains fluorine.  
     
     
         17 . The apparatus of  claim 14  wherein said metal line further comprises: 
 a layer of titanium;  
 a first layer of titanium-nitride;  
 a layer of aluminum or an aluminum-copper alloy; and  
 a second layer of titanium-nitride.  
 
     
     
         18 . The apparatus of  claim 14  wherein said metal line further comprises: 
 a first layer of tantalum or tantalum-nitride;  
 a layer of copper or copper alloy; and  
 a second layer of tantalum or tantalum-nitride.  
 
     
     
         19 . The apparatus of  claim 14  wherein said metal line further comprises: 
 a first layer of titanium/titanium-nitride;  
 a layer of aluminum or an aluminum-copper alloy; and  
 a second layer of titanium/titanium-nitride.  
 
     
     
         20 . The apparatus of  claim 14  wherein the barrier layer is fabricated from a material that impedes corrosion of the metal line by the insulative layer.  
     
     
         21 . The apparatus of  claim 14  wherein the barrier layer is fabricated of a material selected from one or more of the following materials: silicon nitride, silicon oxynitride, and silicon dioxide.  
     
     
         22 . The apparatus of  claim 14  wherein the barrier layer has a thickness of less than 500 Å.  
     
     
         23 . The apparatus of  claim 14  further comprising a second insulative layer disposed over the insulative layer, where both insulative layers define a via containing a conductive liner being fabricated of a conductive material that does not react with the material of the insulative layer.