Method for continuously blending chemical solutions

Abstract

Provided are a method and apparatus for continuously blending a chemical solution for use in semiconductor processing. The method involves the step of mixing a first chemical stream with a second chemical stream in a controlled manner to form a stream of a solution having a predetermined formulation. The apparatus allows one to practice the above method. The method and apparatus can accurately provide chemical solutions of desired concentration in a continuous manner. The invention has particular applicability in semiconductor device fabrication.

1 . A method of continuously blending a chemical solution for use in semiconductor processing, comprising the steps of: 
 a) mixing a first chemical with a second chemical in a first mixing zone in a conduit system and in a real time controlled manner to provide a first solution having a predetermined formulation; the flowrate of the first chemical and the flowrate of the second chemical are continuously adjusted; the first solution formulation is continuously monitored;    b) mixing a third chemical with the first solution in a second mixing zone in said conduit system and in a real time controlled manner to provide a second solution having a predetermined formulation; the flowrate of the third chemical is continuously adjusted; second solution formulation is continuously monitored, wherein steps (a) and (b) are performed contemporaneously; and    c) mixing a fourth chemical with the second solution in a real time controlled manner to provide a third solution having a predetermined formulation; the flowrate of the fourth chemical and the flowrate of the second solution are continuously adjusted; the third solution is continuously monitored; and wherein step (c) is performed contemporaneously with steps (a) and (b).    
   
   
       2 . The method of  claim 1 , wherein step (a), the flowrate of the first chemical or the second chemical is controlled in response to a signal generated by a first sensor which monitors the first solution, and in step (b), the flowrate of the third chemical or the first solution is controlled in response to a signal generated by a second sensor with monitors the second solution.  
   
   
       3 . The method of  claim 2 , wherein the first sensor and the second sensor are of the same or different types, and are selected from the group consisting of conductivity sensors and acoustic signature sensors.  
   
   
       4 . The method of  claim 3 , wherein the first sensor and/or the second sensor is an AC toroid coil sensor.  
   
   
       5 . The method of  claim 3 , wherein the first solution and the second solution are ionic solutions, and the first sensor and the second sensor are conductivity sensors.  
   
   
       6 . The method of  claim 5 , wherein the conductivity sensor is an electrodeless conductivity sensor employing AC toroid coils.  
   
   
       7 . The method of  claim 3 , wherein one of the first solution and the second solution is a non-ionic solution and the other of the first solution and the second solution is an ionic solution.  
   
   
       8 . The method of  claim 1 , wherein the first chemical or the second chemical is deionized water.  
   
   
       9 . The method of  claim 1 , wherein the second solution having a predetermined formulation is directly introduced into a semiconductor processing tool.  
   
   
       10 . The method of  claim 1 , wherein the second mixing zone is arranged downstream from the first mixing zone.  
   
   
       11 . A method of continuously blending a chemical solution on-site at a semiconductor manufacturing facility, comprising the steps of: 
 a) mixing a first chemical with a second chemical in a first mixing zone in a conduit system and in a real time controlled manner to provide a first solution having a predetermined formulation; the flowrate of the first chemical and the flowrate of the second chemical are continuously adjusted; the first solution formulation is continuously monitored;    b) mixing a third chemical with the first solution in a second mixing zone in said conduit system and in a real time controlled manner to provide a second solution having a predetermined formulation; the flowrate of the third chemical is continuously adjusted; the second solution formulation is continuously monitored; wherein steps (a) and (b) are performed contemporaneously;    c) introducing at least part of the second solution having a predetermined formulation into a semiconductor processing tool; and    d) mixing a fourth chemical with at least part of the second solution in a real time controlled manner to provide a third solution having a predetermined formulation; the flowrate of the fourth chemical is continuously adjusted; the third solution formulation is continuously monitored, and wherein step (d) is performed contemporaneously with steps (a) and (b).    
   
   
       12 . The method of  claim 11 , wherein the second solution having a predetermined formulation is directly introduced into a semiconductor processing tool.  
   
   
       13 . The method of  claim 11 , wherein at least part of the third solution having a predetermined formulation is directly introduced into a semiconductor processing tool.