Method of passivating and/or removing contaminants on a low-k dielectric/copper surface

Abstract

One aspect of the invention relates to a method of removing contaminants from a low-k film. The method involves forming a sacrificial layer over the contaminated film. The contaminants combine with the sacrificial layer and are removed by etching away the sacrificial layer. An effective material for the sacrificial layer is, for example, a silicon carbide. The method can be used to prevent the occurrence of pattern defects in chemically amplified photoresists formed over low-k films.

What is claimed is:  
     
         1 . A method of removing a contaminant from a low-k dielectric, comprising: 
 forming a sacrificial layer over the low-k dielectric; and    etching to remove the sacrificial layer.    
     
     
         2 . The method of  claim 1 , wherein the sacrificial layer reacts with the contaminant.  
     
     
         3 . The method of  claim 1 , wherein the sacrificial layer comprises a barrier material.  
     
     
         4 . The method of  claim 3 , wherein the barrier material is silicon carbide.  
     
     
         5 . The method of  claim 1 , wherein the sacrificial layer comprises a material that reacts with ammonia.  
     
     
         6 . The method of  claim 1 , further comprising, after forming the sacrificial layer and before etching the sacrificial layer: 
 forming a layer of a second material that absorbs the contaminant; and    etching to remove the second material.    
     
     
         7 . The method of  claim 6 , wherein the second material is a low-k dielectric.  
     
     
         8 . The method of  claim 1 , further comprising contacting the substrate with a solvent after forming the sacrificial layer and before etching the sacrificial layer.  
     
     
         9 . The method of  claim 8 , wherein the solvent comprises an acidic solution.  
     
     
         10 . The method of  claim 1 , wherein etching to remove the sacrificial layer comprises dry etching with a chemistry that removes small ceramic particles.  
     
     
         11 . A method of patterning a low-k dielectric over a substrate, comprising: 
 forming a sacrificial layer over the substrate;    etching to remove the sacrificial layer;    forming a low-k dielectric layer over the substrate;    coating the low-k dielectric layer with a chemically amplified photoresist;    selectively exposing the photoresist to actinic radiation;    developing the photoresist; and    etching the low-k dielectric layer using the photoresist as a mask.    
     
     
         12 . The method of  claim 11 , wherein the resist comprises a photo-acid.  
     
     
         13 . The method of  claim 11 , further comprising forming a barrier layer over the substrate prior to forming the low-k dielectric layer.  
     
     
         14 . The method of  claim 13 , further comprising forming a second barrier layer over the low-k dielectric layer prior to coating with the resist.  
     
     
         15 . The method of  claim 11 , wherein etching to remove the sacrificial layer comprises dry etching with a chemistry that removes small ceramic particles.  
     
     
         16 . The method of  claim 11 , wherein the substrate comprises a second low-k dielectric layer.  
     
     
         17 . The method of  claim 11  wherein the sacrificial layer reacts with ammonia.  
     
     
         18 . The method of  claim 11  wherein the sacrificial layer comprises SiC.