Apparatus and methods for slurry flow control

Abstract

Apparatus and methods are disclosed for controlling slurry flow in a chemical mechanical polishing apparatus for planarizing an object to be polished by supplying slurry on a grinding pad through a slurry injection nozzle. A disclosed apparatus includes a slurry supply unit; a photo image sensor mounted to one side of a by-pass; a slurry measuring unit for analyzing an image captured by the photo image sensor to measure the sizes of particles and the density of the slurry; and a slurry flow control unit. The disclosed apparatus and methods perform real-time flow control of slurry fed to the injection nozzle through the slurry supply line.

What is claimed is:  
     
         1 . An apparatus to control slurry flow in a chemical mechanical polishing apparatus for planarizing an object to be polished by supplying slurry on a grinding pad through a slurry injection nozzle, the apparatus comprising: 
 a slurry supply unit to supply slurry to the slurry injection nozzle through a slurry supply line;    a photo image sensor to detect a generally cross-sectional image of the slurry flowing in a by-pass diverged from the slurry supply line;    a slurry measuring unit to analyze the image captured by the photo image sensor to measure the sizes of particles included in the slurry and the density of the slurry; and    a slurry flow control unit to control the slurry supply unit based upon the particle sizes and the slurry density measured by the slurry measuring unit.    
     
     
         2 . An apparatus to control slurry flow in a chemical mechanical polishing apparatus for planarizing an object to be polished by supplying slurry on a grinding pad through a slurry injection nozzle, the apparatus comprising: 
 a slurry supply unit to supply slurry to the slurry injection nozzle through a slurry supply line;    a photo image sensor to detect a generally cross-sectional image of the slurry flowing in a by-pass diverged from the slurry supply line;    a slurry measuring unit to analyze the image captured by the photo image sensor to measure the sizes of particles included in the slurry and the density of the slurry;    a diluent solution supply unit to supply diluent solution into the by-pass to reduce a concentration of particles in the slurry; and    a slurry flow control unit to control the slurry supply unit based upon the particle sizes and the slurry density measured by the slurry measuring unit.    
     
     
         3 . An apparatus as defined in  claim 2 , wherein the diluent solution is pure water or a solution with the same composition as the slurry solution.  
     
     
         4 . A method to control slurry flow in a chemical mechanical polishing apparatus for planarizing an object to be polished by supplying slurry on a grinding pad through a slurry injection nozzle, the method comprising: 
 supplying slurry to the slurry injection nozzle through a slurry supply line;    introducing slurry into a by-pass diverged from the slurry supply line;    capturing a cross-sectional image of the by-pass to measure the sizes of particles included in the slurry and the density of the slurry; and    controlling supply of the slurry based upon the measured sizes of particles and density of slurry.    
     
     
         5 . A method to control slurry flow in a chemical mechanical polishing apparatus for planarizing an object to be polished by supplying slurry on a grinding pad through a slurry injection nozzle, the method comprising: 
 supplying slurry to the slurry injection nozzle through a slurry supply line;    introducing slurry into a by-pass diverged from the slurry supply line;    supplying a diluent solution into the by-pass to reduce a concentration of particles of the slurry;    capturing a cross-sectional image of the by-pass to measure the sizes of particles included in the slurry and the density of the slurry; and    controlling supply of the slurry based upon the measured sizes of particles and density of slurry.    
     
     
         6 . A method as defined in  claim 5 , wherein the diluent solution is pure water or a solution with the same composition as the slurry solution.  
     
     
         7 . A method as defined in  claim 5 , wherein the density of the slurry is calculated to be higher in proportion to an amount of supplied diluent solution.  
     
     
         8 . A method as defined in  claim 5 , wherein an amount of the particles is calculated to be higher in proportion to an amount of supplied diluent solution.  
     
     
         9 . A method as defined in  claim 5 , wherein the density of the slurry is calculated to be higher in inverse proportion to the amount of supplied slurry.  
     
     
         10 . A method as defined in  claim 5 , wherein an amount of the particles is calculated to be higher in inverse proportion to the amount of supplied slurry.