Method for monitoring the filling performance of copper plating formula for microvia filling

Abstract

A method for monitoring the filling performance of a copper plating formula for microvia filling includes measuring a first potential value at a first rotation speed and a second potential value at a second rotation speed with a Cu-RDE of a plating solution. Then, a potential difference is obtained by subtracting the potential measured at the second rotation speed from the first rotation speed. The filling performance is defined by the potential difference; that is, a high potential difference indicates a good filling performance.

1 . A method for monitoring the filling performance of a copper plating formula for microvia filling, comprising: 
 measuring a first potential value of the copper plating formula by using a working electrode at a first rotation speed;    measuring a second potential value of the copper plating formula by using the working electrode at a second rotation speed that is different from the first rotation speed; and    calculating a potential difference between the first potential and the second potential, wherein a larger potential difference indicates a better filling performance for microvia filling.    
   
   
       2 . The method of  claim 1 , wherein the filling performance is defined as (the height of the copper deposition in the microvia÷the height of via)×100%.  
   
   
       3 . The method of  claim 1 , wherein the copper plating formula is kept at a temperature of 20˜30° C.  
   
   
       4 . The method of  claim 1 , wherein the copper plating formula comprises cupric sulfate (CuSO 4 ) and sulfuric acid (H 2 SO 4 ).  
   
   
       5 . The method of  claim 1 , wherein the working electrode is a copper rotation disk electrode (Cu-RDE).  
   
   
       6 . The method of  claim 5 , wherein the Cu-RDE is kept at a current density of 10˜20 ASF.  
   
   
       7 . The method of  claim 1 , wherein the first potential value is a potential measured by a working electrode relative to a reference electrode.  
   
   
       8 . The method of  claim 1 , wherein the first rotation speed is 50˜200 rpm.  
   
   
       9 . The method of  claim 1 , wherein the second potential value is a potential measured by a working electrode relative to a reference electrode.  
   
   
       10 . The method of  claim 1 , wherein the second rotation speed is 700˜3000 rpm.