Method for stripping photoresist

Abstract

Disclosed is a method for stripping a photoresist comprising: (I) providing a photoresist pattern on a substrate where the substrate has at least a copper (Cu) wiring and a low-dielectric layer thereon, and selectively etching the low-dielectric layer by using the photoresist pattern as a mask; (II) contacting the substrate after the step (I), with ozone water and/or aqueous hydrogen peroxide; and (III) contacting the substrate after the step (II), with a photoresist stripping solution that contains at least a quaternary ammonium hydroxide. The present invention provides a method for stripping a photoresist that enables to strip effectively photoresist films and etching residues after etching step even in a process not including an O 2 plasma ashing treatment in micropatterning of a substrate having at least Cu wiring and a low-dielectric layer thereon, as in a dual damascene forming process, and, in addition, the method of the invention does not have any negative influence on the dielectric constant of the low-dielectric layer, and ensures an excellent anti-corrosivity.

1 . A method for stripping a photoresist that comprises: 
 (I) selectively etching a low-dielectric layer provided on a substrate, where the substrate has at least a copper (Cu) wiring and the low-dielectric layer thereon, by using a photoresist pattern as a mask which is formed on the substrate;    (II) contacting the substrate after the step (I), with ozone water and/or aqueous hydrogen peroxide; and    (III) contacting the substrate after the step (II), with a photoresist stripping solution that contains at least a quaternary ammonium hydroxide.    
   
   
       2 . The method for stripping a photoresist as claimed in  claim 1 , wherein the low-dielectric layer has a dielectric constant of 3 or less.  
   
   
       3 . The method for stripping a photoresist as claimed in  claim 1 , wherein the quaternary ammonium hydroxide is (a) a quaternary ammonium hydroxide represented by the following general formula (I):  
     
       
         
         
             
             
         
       
     
     wherein R 1 , R 2 , R 3  and R 4  each independently represent an alkyl or hydroxyalkyl group having from 1 to 4 carbon atoms.  
   
   
       4 . The method for stripping a photoresist as claimed in  claim 1 , wherein the photoresist stripping solution contains from 1 to 20% by mass of a quaternary ammonium hydroxide, from 5 to 60% by mass of water, and a water-soluble organic solvent.  
   
   
       5 . The method for stripping a photoresist as claimed in  claim 4 , wherein the water-soluble organic solvent is at lease one selected from dimethylsulfoxide, dimethylimidazolidinone, N-methyl-2-pyrrolidone, diethylene glycol monobutyl ether, sulforane, N,N-dimethylacetamide, and N,N-dimethylformamide.  
   
   
       6 . The method for stripping a photoresist as claimed in  claim 1 , wherein the photoresist stripping solution further contains a water-soluble amine.  
   
   
       7 . The method for stripping a photoresist as claimed in  claim 1 , wherein the photoresist stripping solution further contains at least one selected from aromatic hydroxy compounds, benzotriazole-based compounds, and mercapto group containing compounds.  
   
   
       8 . The method for stripping a photoresist as claimed in  claim 1 , which is used in a process of forming a dual damascene structure.