Wafer cleaning method and equipment

Abstract

There is disclosed a wafer cleaning method comprising supplying a cleaning water to a wafer cleaned with a chemical solution, measuring the resistivity of a solution including the chemical solution and cleaning water, and differentiating the measured value with respect to time, and cleaning the wafer continuously with the cleaning water until the time differential value of the resistivity becomes equal to or less than a preset value and is held at that values for preset time.

1 . A wafer cleaning method comprising: 
 supplying a cleaning water to a wafer cleaned with a chemical solution;    measuring the resistivity of a solution including the chemical solution and cleaning water, and differentiating the measured value with respect to time; and    cleaning the wafer continuously with the cleaning water until the time differential value of the resistivity becomes equal to or less than a preset value and is held at that values for preset time.    
   
   
       2 . The method according to  claim 1 , wherein the wafer is cleaned continuously with the cleaning water until the time differential value of the resistivity becomes equal to or less than 0.05 MΩcm/sec after passing the maximum value, and is held at that value for equal to or more than 5 seconds.  
   
   
       3 . The method according to  claim 1 , wherein the resistivity of the solution is subjected to a predetermined smoothing, and the smoothed value is differentiated with respect to time.  
   
   
       4 . The method according to  claim 1 , wherein the resistivity of the solution in the cleaning tank which contains the wafer when cleaning the wafer with the cleaning water is measured as the resistivity of the solution.  
   
   
       5 . A wafer cleaning method comprising: 
 supplying a cleaning water to a wafer cleaned with a chemical solution;    measuring the conductivity of a solution including the chemical solution and cleaning water, and differentiating the measured value with respect to time; and    cleaning the wafer continuously with the cleaning water until the time differential value of the conductivity becomes equal to or more than a preset value and is held at that values for preset time.    
   
   
       6 . The method according to  claim 5 , wherein the wafer is cleaned continuously with the cleaning water until the time differential value of the conductivity becomes equal to or more than −20 μS/cm·sec after passing the minimum value, and is held at that value for equal to or more than 5 seconds.  
   
   
       7 . The method according to  claim 5 , wherein the conductivity of the solution is subjected to a predetermined smoothing, and the smoothed value is differentiated with respect to time.  
   
   
       8 . The method according to  claim 5 , wherein the conductivity of the solution in the cleaning tank which contains the wafer when cleaning the wafer with the cleaning water is measured as the conductivity of the solution.  
   
   
       9 . A wafer cleaning equipment comprising: 
 a cleaning tank which contains a wafer cleaned with a chemical solution;    a cleaning water supplying unit which supplies the cleaning tank with a cleaning water to clean the wafer;    an electric characteristic measuring unit which measure the resistivity of a solution including the cleaning water and the chemical solution used for cleaning the wafer;    an arithmetic unit which differentiates with respect to time the resistivity of the solution measured with the electric characteristic measuring unit; and    a control unit which operates the cleaning water supplying unit and supplies the cleaning water to the cleaning tank, until the time differential value of the resistivity calculated by the arithmetic unit becomes equal to or less than a preset value and is held at that value for preset time.    
   
   
       10 . The equipment according to  claim 9 , wherein the control unit operates the cleaning water supplying unit and supplies the cleaning water to the cleaning tank, until the time differential value of the resistivity becomes equal to or less than 0.05 MΩcm/sec after passing the maximum value, and is held at that value for equal to or more than 5 seconds.  
   
   
       11 . The equipment according to  claim 9 , wherein the arithmetic unit smoothes the resistivity of the solution, and differentiates the smoothed value with respect to time.  
   
   
       12 . The equipment according to  claim 9 , wherein a take-out port to take out the solution from the cleaning tank is provided at the middle of the cleaning tank, and the electric characteristic measuring unit is provided contacting the solution in the cleaning tank to be taken out through the take-out port.  
   
   
       13 . A wafer cleaning equipment comprising: 
 a cleaning tank which contains a wafer cleaned with a chemical solution;    a cleaning water supplying unit which supplies the cleaning tank with a cleaning water to clean the wafer;    an electric characteristic measuring unit which measures the conductivity of a solution including the cleaning water and the chemical solution used for cleaning the wafer;    an arithmetic unit which differentiates with respect to time the conductivity of the solution measured with the electric characteristic measuring unit; and    a control unit which operates the cleaning water supplying unit and supplies the cleaning water to the cleaning tank, until the time differential value of the conductivity calculated by the arithmetic unit becomes equal to or more than a preset value and is held at that value for preset time.    
   
   
       14 . The equipment according to  claim 13 , wherein the control unit operates the cleaning water supplying unit and supplies the cleaning water to the cleaning tank, until the time differential value of the conductivity becomes equal to or more than −20 μS/cm·sec after passing the minimum value, and is held at that value for equal to or more than 5 seconds.  
   
   
       15 . The equipment according to  claim 13 , wherein the arithmetic unit smoothes the conductivity of the solution, and differentiates the smoothed value with respect to time.  
   
   
       16 . The equipment according to  claim 13 , wherein a take-out port to take out the solution from the cleaning tank is provided at the middle of the cleaning tank, and the electric characteristic measuring unit is provided contacting the solution in the cleaning tank to be taken out through the take-out port.