Assisted rinsing in a single wafer cleaning process

Abstract

The present invention is a method of assisting the rinsing of a wafer in a single wafer cleaning apparatus. According to the present invention, after exposing a wafer to a cleaning and/or etching solution, the cleaning or etching solution is removed from the wafer by spinning the wafer and dispensing or spraying DI water onto the wafer as it is spun. The centrifugal force of the spinning wafer enhances the rinsing of the wafer. In order to enhance the rinsing of the wafer, in an embodiment of the present invention a solution having a lower surface tension than water, such as but not limited to isopropyl alcohol (IPA) is dispensed in liquid or vapor form onto the wafer after the DI water. In a specific embodiment of the present invention, the vapor of a solution with a lower surface tension than DI water, such as IPA vapor, is blown on the wafer in order to break up the DI water bulging up at the center of the spinning wafer. In another embodiment of the present invention, a gas such N2, is blown for a short period of time onto the center of the wafer to break up the DI water bulging up at the center of the spinning wafer. In yet another embodiment of the present invention, acoustic or sonic waves are applied to the wafer as it spins in order to help diffuse the DI water from the wafer. And in still yet another embodiment of the present invention, the DI water which is dispensed onto the spinning wafer is heated to a temperature above room temperature and preferably between 60-70° C. to enhance the diffusion of water from the wafer. The low surface tension liquid, acoustic application, gas blowing, and heated DI water can be used alone or in combination with one another into enhance the rinsing of a wafer and thereby decrease the rinsing time of a single wafer process to less than 20 seconds.

We claim:  
     
         1 . A method of rinsing a wafer comprising: 
 spinning a wafer;    exposing said spinning wafer to DI water; and    after exposing said spinning wafer to DI water, exposing said spinning wafer to a liquid having a lower surface tension than water.    
     
     
         2 . The method of  claim 1  wherein said liquid is isopropyl alcohol (IPA).  
     
     
         3 . The method of  claim 1  further comprising apply acoustic waves to said wafer while exposing said wafer to DI water.  
     
     
         4 . The method of  claim 1  further comprising the step of heating said DI water to a temperature greater than room temperature prior to exposing said spinning wafer to said DI water.  
     
     
         5 . The method of  claim 1  wherein said wafer is spun at a rate between 50-1000 rpms while exposing said wafer to said DI water and to said liquid.  
     
     
         6 . The method of  claim 2  wherein the time of exposure to said liquid is less than time of exposure to said DI water.  
     
     
         7 . A method of rinsing a wafer comprising: 
 spinning said wafer;    exposing said spinning wafer to DI water; and    after exposing said spinning wafer to said DI water, exposing said spinning wafer to the vapor of a solution having a lower surface tension than water.    
     
     
         8 . The method of  claim 7  wherein said solution is isopropyl alcohol (IPA).  
     
     
         9 . The method of  claim 7  further comprising apply acoustic waves to said wafer while exposing said wafer to DI water.  
     
     
         10 . The method of  claim 7  further comprising the step of heating said DI water to a temperature greater than room temperature prior to exposing said spinning wafer to said DI water.  
     
     
         11 . The method of  claim 7  wherein said wafer is spun at a rate between 50-1000 rpm while exposing said wafer to said DI water and to said liquid.  
     
     
         12 . The method of  claim 7  wherein the time of exposure to said vapor is less than time of exposure to said DI water.  
     
     
         13 . A method of rinsing a wafer comprising: 
 spinning a wafer;    exposing said spinning wafer to DI water; and    after exposing said spinning wafer to DI water, blowing a gas at the center of said wafer while said wafer is spinning.    
     
     
         14 . The method of  claim 13  wherein said gas is nitrogen (N 2 ).  
     
     
         15 . The method of  claim 13  further comprising applying acoustic waves to said wafer while exposing said wafer to said DI water.  
     
     
         16 . The method of  claim 13  wherein said DI water is heated to a temperature above room temperature prior to exposing said wafer to said DI water.  
     
     
         17 . A method of rinsing a wafer comprising: 
 spinning a wafer;    exposing said spinning wafer to DI water; and    while exposing said spinning wafer to DI water, applying acoustic waves to said spinning wafer.    
     
     
         18 . The method of  claim 17  wherein said acoustic waves have a frequency in the range between 400 kHz and 8 MHz.  
     
     
         19 . The method of  claim 17  further comprising the step of after exposing said wafer to said DI water exposing said spinning wafer to a liquid having a lower surface tension than water.  
     
     
         20 . The method of  claim 17  wherein said DI water is heated to a temperature greater than room temperature.  
     
     
         21 . A method of rinsing a wafer comprising: 
 spinning said wafer;    exposing said spinning wafer to DI water which has been heated to a temperature greater than room temperature.    
     
     
         22 . The method of  claim 21  wherein said DI water is heated to a temperature between 60-70° C.  
     
     
         23 . The method of  claim 21  further comprising applying acoustic waves to said wafer while exposing said wafer to said heated DI water.  
     
     
         24 . The method of  claim 21  further comprising after exposing said spinning wafer to said heated DI water, exposing said spinning wafer to a liquid having a lower surface tension than water.  
     
     
         25 . A method of rinsing a wafer comprising: 
 spinning said wafer;    exposing said spinning wafer to DI water heated to a temperature greater than room temperature;    while exposing said spinning wafer to said heated DI water, applying acoustic waves to said spinning wafer; and    after exposing said spinning wafer to said heated DI water, exposing said wafer to a liquid having lower surface tension than water.    
     
     
         26 . A method of cleaning a wafer comprising: 
 spinning a wafer at a first rotation rate;    exposing said spinning wafer to an etchant or cleaning chemicals;    rinsing said cleaning chemicals or said etchant from said wafer with a rinsing method comprising: 
 spinning said wafer at a second rotation rate;  
 dispensing DI water onto said spinning wafer; and  
 exposing said spinning wafer to a vapor or liquid having a lower surface tension than water; and  
   after rinsing said wafer, drying said wafer by spinning said wafer at a third rotation rate.    
     
     
         27 . The method of  claim 26  wherein said third rotation rate is faster than said second rotation rate.  
     
     
         28 . The method of  claim 27  wherein said second rotation rate is between 50-1000 rpm and said third rotation rate is between 500-2000 rpm.  
     
     
         29 . The method of  claim 26  wherein said liquid or vapor is isopropyl alcohol.  
     
     
         30 . The method of  claim 26  wherein said rinsing method further comprises applying acoustic waves to said wafer while dispensing DI water on said wafer.  
     
     
         31 . The method of  claim 26  wherein said DI water is heated to a temperature greater than room temperature prior to dispensing said DI water on said spinning wafer.  
     
     
         32 . A method of cleaning a wafer comprising: 
 spinning a wafer;    exposing said spinning wafer to an etchant or cleaning chemicals;    prior to dispensing DI water on said etchant or cleaning chemical covered wafer exposing said spinning wafer to a liquid or vapor having a lower surface tension than water.    
     
     
         33 . A method of cleaning a wafer comprising: 
 spinning said wafer;    exposing said spinning wafer to an etchant or a cleaning chemical; and    rinsing said etchant or cleaning chemical from said wafer by simultaneously dispensing DI water on said spinning wafer and exposing said spinning wafer to a liquid or vapor having a lower surface tension than water.