Copper technology for ULSI metallization

Abstract

A copper damascene structure formed by direct patterning of a low-dielectric constant material is disclosed. The copper damascene structure includes a tungsten nitride barrier layer formed by atomic layer deposition using sequential deposition reactions. Copper is selectively deposited by a CVD process and/or by an electroless deposition technique.

What is claimed as new and desired to be protected by Letters Patent of the United States is:  
     
         1 . A method of forming a copper damascene structure, said method comprising the steps of: 
 directly patterning a low-dielectric constant layer to form at least one opening through said low-dielectric constant layer;    forming a tungsten nitride layer by atomic-layer deposition using sequential surface reactions, said tungsten nitride layer being in contact with said at least one opening; and    providing a copper layer in said at least one opening.    
     
     
         2 . The method of  claim 1 , wherein said low-dielectric constant layer includes a material selected from the group consisting of methylsilsequiazane, polyimide, spin-on-polymers, flare, polyarylethers, parylene, polytetrafluoroethylene, benzocyclobutene, SILK, fluorinated silicon oxide, hydrogen silsesquioxane and NANOGLASS.  
     
     
         3 . The method of  claim 1 , wherein said low-dielectric constant layer comprises methylsilsequiazane.  
     
     
         4 . The method of  claim 3 , wherein said step of forming said at least one opening further comprises patterning said low-dielectric constant layer.  
     
     
         5 . The method of  claim 4 , wherein said step of patterning said low-dielectric constant layer further comprises exposing said low-dielectric constant layer to an electron beam or ultra violet light.  
     
     
         6 . The method of  claim 5 , wherein said step of forming said at least one opening further comprises etching said low-dielectric constant layer with a tetramethyl-ammonium hydroxide solution.  
     
     
         7 . The method of  claim 3 , wherein said low-dielectric constant layer is formed by spin coating to a thickness of about 2,000 to 50,000 Angstroms.  
     
     
         8 . The method of  claim 7 , wherein said low-dielectric constant layer is formed by spin coating to a thickness of about 5,000 to 20,000 Angstroms.  
     
     
         9 . The method of  claim 1 , wherein said tungsten nitride layer is formed at a temperature of about 550-800K.  
     
     
         10 . The method of  claim 1 , wherein said copper layer is selectively deposited by chemical vapor deposition.  
     
     
         11 . The method of  claim 10 , wherein said copper layer is selectively deposited at a temperature of about 300° C. to about 400° C.  
     
     
         12 . The method of  claim 11 , wherein said copper layer is selectively deposited in an atmosphere of pure hydrogen from the β-diketonate precursor bis(6,6,7,8,8,8-heptafluoro-2,2-dimetyl 1-3,5-octanedino) copper (II).  
     
     
         13 . The method of  claim 11 , wherein said copper layer is selectively deposited in an atmosphere of pure argon from the β-diketonate precursor bis(6,6,7,8,8,8-heptafluoro-2,2-dimetyl 1-3,5-octanedino) copper (II).  
     
     
         14 . The method of  claim 1 , wherein said copper layer is formed by electroless deposition.  
     
     
         15 . The method of  claim 1  further comprising the act of chemical mechanical polishing said tungsten nitride layer.  
     
     
         16 . The method of  claim 1  further comprising the act of chemical mechanical polishing said copper layer.  
     
     
         17 . A method of forming a copper damascene structure, said method comprising the steps of: 
 forming a material layer of methylsilsequiazane over a substrate;    forming at least one opening through said methylsilsequiazane layer;    forming a tungsten nitride layer by atomic-layer deposition using sequential surface reactions, said tungsten nitride layer being in contact with said at least one opening; and    providing a copper layer in said at least one opening.    
     
     
         18 . The method of  claim 17 , wherein said step of forming said at least one opening further comprises directly patterning said methylsilsequiazane layer with a mask to form said at least one opening.  
     
     
         19 . The method of  claim 18 , wherein said step of directly patterning said methylsilsequiazane layer further comprises exposing said methylsilsequiazane layer to an electron beam or ultra violet light.  
     
     
         20 . The method of  claim 19 , wherein said step of forming said at least one opening further comprises etching said methylsilsequiazane layer with a tetramethyl-ammonium hydroxide solution.  
     
     
         21 . The method of  claim 17 , wherein said methylsilsequiazane layer is formed by spin coating to a thickness of about 21,000 to 50,000 Angstroms.  
     
     
         22 . The method of  claim 21 , wherein said methylsilsequiazane layer is formed by spin coating to a thickness of about 5,000 to 20,000 Angstroms.  
     
     
         23 . The method of  claim 17 , wherein said tungsten nitride layer is formed at a temperature of about 550-800K.  
     
     
         24 . The method of  claim 17 , wherein said copper layer is selectively deposited by chemical vapor deposition.  
     
     
         25 . The method of  claim 24 , wherein said copper layer is selectively deposited at a temperature of about 300° C. to about 400° C.  
     
     
         26 . The method of  claim 25 , wherein said copper layer is selectively deposited in an atmosphere of pure hydrogen from the β-diketonate precursor bis(6,6,7,8,8,8-heptafluoro-2,2-dimetyl 1-3,5-octanedino) copper (II).  
     
     
         27 . The method of  claim 25 , wherein said copper layer is selectively deposited in an atmosphere of pure argon from the β-diketonate precursor bis(6,6,7,8,8,8-heptafluoro-2,2-dimetyl 1-3,5-octanedino) copper (II).  
     
     
         28 . The method of  claim 17 , wherein said copper layer is formed by electroless deposition.  
     
     
         29 . The method of  claim 17  further comprising the act of chemical mechanical polishing said tungsten nitride layer.  
     
     
         30 . The method of  claim 17  further comprising the act of chemical mechanical polishing said copper layer.  
     
     
         31 . A dual damascene structure comprising: 
 a substrate;    a metal layer provided within said substrate;    a methylsilsequiazane layer located over said substrate;    a via situated within said methylsilsequiazane layer and extending to at least a portion of said metal layer, said via being lined with a tungsten nitride layer and filled with a copper material; and    a trench situated within said methylsilsequiazane layer and extending to said via, said trench being lined with said tungsten nitride layer and filled with said copper material.    
     
     
         32 . The dual damascene structure of  claim 31 , wherein said methylsilsequiazane layer has a thickness of about 2,000 to 50,000 Angstroms.  
     
     
         33 . The dual damascene structure of  claim 31 , wherein said tungsten nitride layer has a thickness of about 50 to 200 Angstroms.  
     
     
         34 . The dual damascene structure of  claim 31 , wherein said tungsten nitride layer is a sequential atomic layer deposition tungsten nitride layer.  
     
     
         35 . The dual damascene structure of  claim 31 , wherein said substrate is a semiconductor substrate.  
     
     
         36 . The dual damascene structure of  claim 31 , wherein said substrate is a silicon substrate.  
     
     
         37 . A damascene structure comprising: 
 a substrate;    a metal layer provided within said substrate;    a methylsilsequiazane layer located over said substrate; and    at least one opening situated within said methylsilsequiazane layer and extending to at least a portion of said metal layer, said opening being lined with a tungsten nitride layer and filled with a copper material.    
     
     
         38 . The damascene structure of  claim 37 , wherein said methylsilsequiazane layer has a thickness of about 2,000 to 50,000 Angstroms.  
     
     
         39 . The damascene structure of  claim 37 , wherein said tungsten nitride layer has a thickness of about 50 Angstroms to about 200 Angstroms.  
     
     
         40 . The damascene structure of  claim 37 , wherein said tungsten nitride layer is a sequential atomic layer deposition tungsten nitride layer.  
     
     
         41 . The damascene structure of  claim 37 , wherein said copper material includes copper or a copper alloy.  
     
     
         42 . The damascene structure of  claim 37 , wherein said substrate is a semiconductor substrate.  
     
     
         43 . The damascene structure of  claim 37 , wherein said substrate is a silicon substrate.  
     
     
         44 . A processor-based system comprising: 
 a processor; and    an integrated circuit coupled to said processor, at least one of said processor and integrated circuit including a damascene structure, said damascene structure comprising a metal layer over a substrate, a methylsilsequiazane layer over said metal layer, and at least one opening situated within said methylsilsequiazane layer and extending to at least a portion of said metal layer, said opening being lined with a tungsten nitride layer and filled with copper.    
     
     
         45 . The processor-based system of  claim 44 , wherein said processor and said integrated circuit are integrated on same chip.