System and method for chemical mechanical polishing using retractable polishing pads

Abstract

A chemical mechanical polishing includes a first spindle operable to rotate with respect to a central axis of the first spindle. A first polishing pad is coupled with the first spindle, and the first polishing pad has a first surface extending along a plane generally perpendicular to the central axis of the first spindle. A wafer carrier is included that is adapted to receive a wafer with a second surface generally parallel to the first surface of the first polishing pad. The wafer carrier is operable to rotate with respect to a central axis of the wafer carrier. The first surface of the first polishing pad is moveable along the central axis of the first spindle from a first position, wherein the first surface is spaced from the second surface, and a second position, wherein the first surface generally contacts the second surface.

What is claimed is:  
     
         1 . An apparatus, comprising: 
 a first spindle operable to rotate with respect to a central axis of the first spindle;    a first polishing pad coupled with the first spindle, the first polishing pad having a first surface extending along a plane generally perpendicular to the central axis of the first spindle;    a wafer carrier adapted to receive a wafer, the wafer having a second surface generally parallel to the first surface of the first polishing pad, the wafer carrier operable to rotate with respect to a central axis of the wafer carrier; and    wherein the first surface is moveable along the central axis of the first spindle from a first position wherein the first surface is spaced from the second surface, and a second position wherein the first surface generally contacts the second surface.    
     
     
         2 . The apparatus of  claim 1 , wherein the first surface is moveable along a first axis generally perpendicular to the central axis of the first spindle.  
     
     
         3 . The apparatus of  claim 1 , further comprising: 
 a second spindle operable to rotate with respect to a central axis of the second spindle, the central axis of the second spindle being approximately parallel to the central axis of the first spindle; and    a second polishing pad coupled with the second spindle, the second polishing pad being moveable along the central axis of the second spindle to a third position in which the second polishing pad generally contacts the second surface.    
     
     
         4 . The apparatus of  claim 3 , wherein the second polishing pad is moveable along a second axis generally perpendicular to the central axis of the second spindle.  
     
     
         5 . The apparatus of  claim 3 , wherein the first and second polishing pads each generally contact the second surface at one time.  
     
     
         6 . The apparatus of  claim 3 , further comprising independent first and second controllers operable to control movement of the first and second polishing pads, respectively.  
     
     
         7 . The apparatus of  claim 3 , further comprising first and second endpoint detection systems operable to detect the locations of the first and second polishing pads, respectively, with respect to the second surface.  
     
     
         8 . The apparatus of  claim 3 , further comprising independent first and second fluid delivery dispensers operable to provide fluids to first and second locations adjacent the first and second polishing pads, respectively.  
     
     
         9 . The apparatus of  claim 3 , further comprising independent first and second deionized water delivery dispensers operable to provide deionized water to first and second locations adjacent the first and second polishing pads, respectively.  
     
     
         10 . The apparatus of  claim 3 , wherein the first polishing pad and the second polishing pad apply downward forces upon the second surface.  
     
     
         11 . The apparatus of  claim 10 , further comprising independent first and second controllers operable to control application of downward forces upon the second surface by the first and second polishing pads, respectively.  
     
     
         12 . The apparatus of  claim 1 , wherein the first surface has a diameter less than a diameter of the second surface.  
     
     
         13 . The apparatus of  claim 12 , wherein the diameter of the first surface is approximately one-sixteenth the diameter of the second surface.  
     
     
         14 . The apparatus of  claim 12 , wherein the diameter of the first surface is approximately 0.75 inches.  
     
     
         15 . An apparatus, comprising: 
 a first spindle operable to rotate with respect to a central axis of the first spindle;    a first polishing pad coupled with the first spindle, the first polishing pad having a first surface extending along a plane generally perpendicular to the central axis of the first spindle;    the first surface moveable along a first axis, the first axis generally perpendicular to the central axis of the first spindle;    a second spindle operable to rotate with respect to a central axis of the second spindle;    a second polishing pad coupled with the second spindle;    the second polishing pad moveable along a second axis, the second axis generally perpendicular to the central axis of the second spindle; and    a wafer carrier having a second surface generally parallel to the first surface of the first polishing pad, the second surface operable to rotate with respect to a central axis of the wafer carrier, the second surface being adapted to receive a wafer.    
     
     
         16 . The apparatus of  claim 15 , wherein: 
 the first surface is moveable along the central axis of the first spindle from a first position wherein the first surface is spaced from the second surface and a second position wherein the first surface generally contacts the second surface; and    the second polishing pad is moveable along the central axis of the second spindle to a third position in which the second polishing pad generally contacts the second surface.    
     
     
         17 . The apparatus of  claim 16 , wherein the first and second polishing pads each generally contact the second surface second surface at one time.  
     
     
         18 . The apparatus of  claim 15 , further comprising independent first and second controllers operable to control movement of the first and second polishing pads.  
     
     
         19 . The apparatus of  claim 15 , further comprising first and second endpoint detection systems operable to detect the locations of the first and second polishing pads, respectively, with respect to the second surface.  
     
     
         20 . The apparatus of  claim 15 , further comprising independent first and second fluid delivery dispensers operable to provide fluids to first and second locations adjacent the first and second polishing pads, respectively.  
     
     
         21 . The apparatus of  claim 15 , further comprising deionized water delivery systems operable to provide deionized water to first and second locations adjacent the first and second polishing pads, respectively.  
     
     
         22 . The apparatus of  claim 15 , wherein the first surface has a diameter less than a diameter of the second surface.  
     
     
         23 . The apparatus of  claim 22 , wherein the diameter of the first surface is approximately one-sixteenth the diameter of the second surface.  
     
     
         24 . The apparatus of  claim 22 , wherein the diameter of the first surface is approximately 0.75 inches.  
     
     
         25 . A method for polishing a silicon wafer, comprising: 
 polishing the silicon wafer with a first polishing pad and a second polishing pad at one time, the silicon wafer having a first surface;    moving the first polishing pad along a central axis of a first spindle, the first spindle coupled with the first polishing pad; and    moving the second polishing pad along a central axis of a second spindle, the second spindle coupled with the second polishing pad.    
     
     
         26 . The method of  claim 25 , further comprising: 
 moving the first polishing pad along a first axis, the first axis generally perpendicular to the central axis of the first spindle; and    moving the second polishing pad along a second axis, the second axis generally perpendicular to the central axis of the second spindle.    
     
     
         27 . The method of  claim 25 , further comprising 
 controlling the movement of the first polishing pad and the second polishing pad with independent first and second controllers, respectively.    
     
     
         28 . The method of  claim 25 , further comprising monitoring a first thickness of the silicon wafer at a first location on the wafer and a second thickness of the silicon wafer at a second location on the wafer with first and second endpoint detection systems, respectively, wherein first and second endpoint detection systems are adjacent first and second polishing pads, respectively.  
     
     
         29 . The method of  claim 28 , further comprising adjusting the locations of the first polishing pad and the second polishing pad along the central axis of the first spindle and the central axis of the second spindle, respectively, based upon the first thickness and the second thickness.  
     
     
         30 . The method of  claim 25 , further comprising providing fluids to the first surface of the silicon wafer with first and second fluid delivery dispensers, wherein first and second fluid delivery dispensers are adjacent first and second polishing pads, respectively.  
     
     
         31 . The method of  claim 25 , wherein the first polishing pad has a second surface having a diameter less than a diameter of the first surface of the silicon wafer.  
     
     
         32 . The method of  claim 31 , wherein the diameter of the second surface is approximately one-sixteenth the diameter of the first surface.  
     
     
         33 . An apparatus, comprising: 
 first, second, third and fourth spindles operable to rotate with respect to respective central axes of the first, second, third and fourth spindles;    first, second, third and fourth polishing pads coupled with the first, second, third and fourth spindles, respectively, the first polishing pad having a first surface extending along a plane generally perpendicular to the central axis of the first spindle;    a wafer carrier disposed below the first, second, third and fourth polishing pads, the wafer carrier operable to rotate with respect to a central axis of the wafer carrier, the wafer carrier adapted to receive a silicon wafer, the silicon wafer having a second surface extending along a plane generally parallel to the first surface of the first polishing pad, the second surface having a diameter approximately sixteen times a diameter of the first surface;    the first, second, third and fourth spindles further operable to move along the respective central axes of the first, second, third and fourth spindles, to respective first, second, third and fourth positions, in which the first, second, third, and fourth spindles generally contact the second surface;    the first, second, third and fourth spindles further operable to move along respective first, second, third and fourth linear axes, wherein the first, second, third and fourth linear axes are generally perpendicular to the central axis of the first spindle;    the first, second, third and fourth polishing pads each generally contact the second surface at one time;    first, second, third and fourth endpoint detection systems operable to detect the locations of the first, second, third and fourth polishing pads, respectively, with respect to the second surface;    first, second, third and fourth controllers operable to control movement of the first, second, third and fourth polishing pads, respectively;    first, second, third and fourth fluid delivery dispensers operable to provide fluids to the second surface adjacent the first, second, third and fourth polishing pads, respectively; and    first, second, third and fourth deionized water delivery dispensers operable to provide deionized water to the second surface adjacent the first, second, third and fourth polishing pads, respectively.    
     
     
         34 . A method for polishing a silicon wafer, comprising: 
 polishing the silicon wafer with first, second, third and fourth polishing pads at one time, the silicon wafer having a first surface;    moving the first, second, third and fourth polishing pads along respective central axes of the first, second, third and fourth polishing pads;    moving the first, second, third and fourth polishing pads along respective first, second, third and fourth axes, the first, second, third and fourth axes generally perpendicular to the central axis of the first polishing pad;    controlling the movement of the first, second, third and fourth polishing pads with independent first, second, third and fourth controllers, respectively;    monitoring first, second, third and fourth thicknesses of the silicon wafer at first, second, third and fourth locations, respectively, with first, second, third and fourth endpoint detection systems, respectively, wherein first, second, third and fourth endpoint detection systems are adjacent first, second, third and fourth polishing pads, respectively;    adjusting the locations of the first, second, third and fourth polishing pads along the respective central axes of the first, second, third and fourth spindles, based upon the first, second, third and fourth thicknesses, respectively; and    providing fluids to the first surface of the silicon wafer with first, second, third and fourth fluid delivery dispensers, wherein first, second, third and fourth fluid delivery dispensers are adjacent first, second, third and fourth polishing pads, respectively.