Systems and methods for wafer polishing

Abstract

An electromagnetic polish head ( 100 ) comprises at least one electromagnet. An embodiment may also include the addition of a slurry component or components that can be affected by an electromagnetic field. During polishing or planarization, a field or fields may be generated by the polish head ( 100 ) to affect the polishing of a wafer by attracting or repelling the slurry to a portion or portions of the substrate.

1 . A polish head for polishing a substrate comprising: 
 a carrier head for holding the substrate during polishing; and    an electromagnet within the carrier head for affecting a slurry's distribution across at least a portion of the substrate's surface during polishing with a Polish pad.    
   
   
       2 . The polish head of  claim 1  wherein an electromagnetic field generated by the electromagnet affects the rate of polishing on at least a portion of the substrate by attracting said slurry to said portion of the substrate.  
   
   
       3 . The polish head of  claim 1  wherein an electromagnetic field generated by the electromagnet affects the rate of polishing on at least a portion of the substrate by repelling said slurry from said portion of the substrate.  
   
   
       4 . The polish head of  claim 1  wherein an electromagnetic field generated by the electromagnet is varied during polishing.  
   
   
       5 . The polish head of  claim 1  further comprising at least one additional electromagnet.  
   
   
       6 . The polish head of  claim 5  wherein electromagnetic fields generated by the electromagnets affect the rate of polishing on at least a portion of the substrate by attracting said slurry to said portion of the substrate.  
   
   
       7 . The polish head of  claim 5  wherein at least one of the electromagnets generates an electromagnetic field that is varied during polishing.  
   
   
       8 . The polish head of  claim 5  wherein the carrier head rotates during polishing.  
   
   
       9 . A method for affecting the polishing rate on at least a portion of a substrate comprising: 
 using a slurry with at least one component capable of being affected by a electromagnetic field;    placing the substrate on a polish head comprising an electromagnet;    using the electromagnet to generate an electromagnetic field to affect the slurry's distribution across at least a portion of the substrate's surface while polishing with a polish pad.    
   
   
       10 . The method of  claim 9  further comprising a step of using a feedback system to determine an adjustment to the electromagnetic field.  
   
   
       11 . The method of  claim 10  wherein the feedback system is an open-loop feedback system.  
   
   
       12 . The method of  claim 11  wherein the step of using the open-loop feedback system comprises obtaining a substrate profile.  
   
   
       13 . The method of  claim 12  wherein the substrate profile is determined from measuring the profile of a sample substrate.  
   
   
       14 . The method of  claim 10  wherein the feedback system is a closed-loop feedback system.  
   
   
       15 . The method of  claim 14  wherein the step of using the closed-loop feedback system comprises obtaining a substrate profile using reflectance/transmittance measurements.  
   
   
       16 . The method of  claim 14  wherein the step of using the closed-loop feedback system comprises using the polish head's motor current to determine the adjustment to the electromagnetic field.  
   
   
       17 . The method of  claim 9  wherein the slurry comprises at least one iron, nickel, or cobalt component.  
   
   
       18 . The method of  claim 9  further comprising the step of generating at least two electromagnetic fields.  
   
   
       19 . A slurry for use with a polish head and polish pad for polishing a substrate, said polish head comprising a carrier head for holding the substrate during polishing and an electromagnet within the carrier head that generates an electromagnetic field, the slurry comprising at least one polarizeable component that is affected by the electromagnetic field generated by the electromagnet wherein the slurry's distribution across at least a portion of a substrate's surface may be affected to be non-uniform during polishing.  
   
   
       20 . The slurry of  claim 19  wherein the polarizeable component is selected from a group comprising a ferromagnetic component, a paramagnetic component and both ferromagnetic and paramagnetic components.