Brushless multipass silicon wafer cleaning process for post chemical mechanical polishing using immersion

Abstract

A method for removing a slurry from a silicon wafer after chemical-polishing whereby the wafer is subjected to at least 2 or more chemical megasonic baths for a short duration of time. The pH of the first megasonic bath matches the pH of the slurry to be removed.

I claim:  
     
         1 . A method of cleaning a substance from the surface of a silicon wafer comprising: 
 determining the pH of substances on the surface of the wafer;    adjusting the pH of a megasonic chemical bath to match the pH of the substance;    immersing the wafer in a first chemical megasonic bath with a pH that matches the pH of the substance to be removed;    cleaning the wafer in the megasonic bath.    
     
     
         2 . The method of cleaning a silicon wafer of  claim 1  wherein the substance to be removed is slurry used in chemical-mechanical polishing.  
     
     
         3 . The method of cleaning a silicon wafer of  claim 1  further comprising: immersing the wafer in a second chemical megasonic bath.  
     
     
         4 . The method of cleaning a silicon wafer of  claim 1  further comprising: immersing the wafer in a second chemical megasonic bath with a pH that approximately matches the pH of the substance to be removed.  
     
     
         5 . The method of cleaning a silicon wafer of  claim 1  further wherein the the duration of the first chemical megasonic bath is no less than 10 minutes and is no more than 15 minutes.  
     
     
         6 . The method of cleaning a silicon wafer of  claim 1  further wherein the the duration of the first chemical megasonic bath is no less than 5 minutes and is no more than 10 minutes.  
     
     
         7 . The method of cleaning a silicon wafer of  claim 1  further wherein the the duration of the first chemical megasonic bath is no more than 5 minutes.