Polishing method for selective chemical mechanical polishing of semiconductor substrates

Abstract

A chemical mechanical polishing method is provided for polishing substrates with one or more barrier layers on an underlying dielectric layer utilizing a polishing composition with a high selectivity for removal of the barrier layer material (for e.g. tantalum) resulting in a substrate with a planar dielectric layer with minimal scratching and erosion.

What is claimed is:  
     
         1 . A method for selectively removing one or more barrier layers from a semiconductor substrate containing an underlying dielectric layer, comprising the steps of: 
 providing a substrate having a barrier layer requiring removal;    providing a polishing pad;    biasing said substrate and said polishing pad under a fixed pressure; and    dispensing a polishing composition at an interface between the substrate and the polishing pad thereby removing the barrier layer;    wherein said polishing composition has as a constituent, a polymer having at least two functional groups forming intermolecular hydrogen bonds with silanol and siloxane groups on said dielectric layer thereby suppressing removal of the dielectric layer.    
     
     
         2 . The method of  claim 1  performed on a substrate containing one or more barrier layers wherein said barrier layer is made of a material selected from a group consisting of tantalum, tantalum nitride, titanium, titanium nitride or combinations thereof.  
     
     
         3 . The method of  claim 2  performed with said polishing composition having an alkaline pH in a range of about 7 to 11, comprising: 
 abrasive particles;  
 an inhibitor;  
 a dispersant;  
 a biocide; and  
 a nitrogen-containing polymeric compound.  
 
     
     
         4 . The method of  claim 3  performed with said polishing composition containing up to about 30% by weight colloidal silica wherein the nitrogen-containing polymeric compound is selected from a group consisting of polyacrylamides and polyethyleneimines.  
     
     
         5 . The method of  claim 4  wherein the method is performed with a polishing composition containing a polyethyleneimine with an average molecular weight in a range of about 500 to about 1000.  
     
     
         6 . The method of  claim 5  wherein the method is performed with a polishing composition containing a mixture of low-molecular weight polyethyleneimines and high molecular weight polyethyleneimines such that the number average molecular weight of said mixture is in a range of about 500 to 1,000.  
     
     
         7 . The method of  claim 6  wherein the method is performed with a polishing composition wherein said inhibitor is an aromatic triazole selected from a group consisting of benzotriazole, tolyltriazole or mixtures thereof.  
     
     
         8 . The method of  claim 5  wherein the method is performed with a polishing composition wherein said inhibitor is an aromatic triazole selected from a group consisting of benzotriazole, tolyltriazole or mixtures thereof.  
     
     
         9 . A method of polishing by CMP using abrasives and a polishing fluid to remove a barrier layer from an underlying dielectric layer, comprising: 
 polishing the barrier layer while using a polishing composition having as a constituent, organic molecules having at least two functional groups forming intermolecular hydrogen bonds with silanol groups on the dielectric layer, said organic molecules resisting removal of the dielectric layer during polishing.