Localized doping and /or alloying of metallization for increased interconnect performance

Abstract

Methods and compositions are disclosed for modifying a semiconductor interconnect layer to reduce migration problems while minimizing resistance increases induced by the modifications. One method features creating trenches in the interconnect layer and filling these trenches with compositions that are less susceptible to migration problems. The trenches may be filled using traditional vapor deposition methods, or electroplating, or alternately by using electroless plating methods. Ion implantation may also be used as another method in modifying the interconnect layer. The methods and compositions for modifying interconnect layers may also be limited to the via/interconnect interface for improved performance. A thin seed layer may also be placed on the semiconductor substrate prior to applying the interconnect layer. This seed layer may also incorporate similar dopant and alloying materials in the otherwise pure metal.

What is claimed is:  
     
         1 . A method for constructing an electrical interconnect having enhanced mechanical properties on a semiconductor substrate, comprising: 
 formation of a first recess in an electrically-insulating material;    deposition of a first electrically-conductive material in the first recess formation of a second recess in the first electrically-conductive material; and    deposition of a second electrically-conductive material in the second recess.    
     
     
         2 . The method of  claim 1 , wherein the second electrically-conductive material is deposited by electroless plating.  
     
     
         3 . The method of  claim 2 , wherein the depth of the second recess is in the range of about 50 to about 500 Angstroms.  
     
     
         4 . The method of  claim 3 , wherein the second electrically-conductive material comprises copper and at least one material selected from the group consisting of arsenic, antimony, chromium, palladium, tin, magnesium, aluminum, cobalt, and zirconium.  
     
     
         5 . The method of  claim 4 , wherein copper is present in the second electrically-conductive material at a concentration of between about 95 and about 99.9 weight percent.  
     
     
         6 . The method of  claim 1 , wherein the deposition of the second electrically-conductive material by a vapor deposition technique.  
     
     
         7 . The method of  claim 1 , wherein the formation of the second recess results at least in part from chemically etching the first electrically-conductive material.  
     
     
         8 . The method of  claim 1 , wherein the formation of the second recess results at least in part from over polishing during a chemical mechanical polish (“CMP”) step.  
     
     
         9 . The method of  claim 1 , wherein the first recess comprises a secondary trench overlying a primary trench and wherein the second recess in the first conductive material is located primarily above the primary trench.  
     
     
         10 . A method for constructing an electrical interconnect having enhanced mechanical properties on a semiconductor substrate, comprising: 
 formation of a first recess in an electrically-insulating material;    deposition of a thin seed layer of a first electrically-conductive material in the first recess;    deposition of a second electrically-conductive material in the first recess;    formation of a second recess in the second electrically-conductive material; and    deposition of a third electrically-conductive material in the second recess.    
     
     
         11 . The method of  claim 10 , wherein the deposition of the thin seed layer occurs by electroless plating.  
     
     
         12 . The method of  claim 10 , wherein the deposition of the third electrically-conductive material occurs by electroless plating.  
     
     
         13 . The method of  claim 11 , wherein the thin seed layer has a thickness in the range of about 10 to about 50 Angstroms.  
     
     
         14 . The method of  claim 11 , wherein the first and third electrically-conductive materials comprise copper and a material selected from the group consisting of arsenic, antimony, chromium, palladium, tin, magnesium, aluminum, cobalt, and zirconium.  
     
     
         15 . The method of  claim 14 , wherein the first and the third electrically-conductive materials contain an amount of non-copper material in the range of about 0.1 to about 10.0 percent by weight.  
     
     
         16 . The method of  claim 11 , wherein the second recess has a depth in the range of about 50 to about 500 Angstroms.  
     
     
         17 . The method of  claim 10 , wherein the deposition of the thin seed layer occurs by atomic layer growth.  
     
     
         18 . The method of  claim 10 , wherein the first recess comprises a secondary trench overlying a primary trench and wherein the second recess is located primarily above the primary trench.  
     
     
         19 . A method for constructing an electrical interconnect having enhanced mechanical properties on a semiconductor substrate, comprising: 
 formation of a recess in an electrically-insulating material;    deposition of an electrically-conductive material in the recess; and    ion implantation of a chemical species onto the electrically-conductive material.    
     
     
         20 . The method of  claim 19 , wherein the recess comprises a secondary trench overlying a primary trench and wherein ion implantation is performed primarily in the overlying region of the primary and secondary trenches.  
     
     
         21 . The method of  claim 20 , wherein a majority of the ion implantation is performed at a depth of about 50 to about 500 Angstroms.  
     
     
         22 . The method of  claim 21 , wherein the amount of ion implantation results in a concentration of the chemical species within the electrically-conductive material of about 0.1 to about 10.0 percent by weight.  
     
     
         23 . The method of  claim 22 , wherein the electrically-conductive material comprises copper, and the chemical species comprises a material selected from the group consisting of arsenic, antimony, chromium, palladium, tin, magnesium, aluminum, cobalt, and zirconium.  
     
     
         24 . The method of  claim 22 , wherein the electrically-conductive material comprises aluminum, and the chemical species comprises a material selected from the group consisting of arsenic, antimony, chromium, palladium, tin, magnesium, aluminum, cobalt, and zirconium.  
     
     
         25 . The method of  claim 22 , wherein the electrically-conductive material comprises tungsten, and the chemical species comprises a material selected from the group consisting of arsenic, antimony, chromium, palladium, tin, magnesium, aluminum, cobalt, and zirconium.