Wafer Carrier Pivot Mechanism

Abstract

A pivoting wafer carrier having a minimum of internal friction and a smooth, continuous pivoting motion. The pivot mechanism includes a lower ring mounted on a pressure plate, an upper ring mounted on a housing upper plate and ball transfer units disposed on the lower ring. Corresponding bearing wedges depend downwardly from the upper ring. As the pressure plate tilts during the polishing process, the load balls of the ball transfer units roll against the corresponding wedges, thus producing a smooth, continuous pivoting motion. A universal joint may be provided to the carrier to effect the rotation of the carrier and to aid the smooth, continuous pivoting motion of the wafer carrier.

1 . A CMP wafer carrier adapted to engage a spindle having an axis of rotation, the wafer carrier comprising: 
 an upper plate coaxially secured to the spindle, the upper plate including a means for transmitting rotational force and a means for transmitting load force;    a pressure plate including a means for receiving rotational force, and a means for receiving load force; and    a spider for transferring rotational force, the spider engaging the means for transmitting rotational force and the means for receiving rotational force.    
     
     
         2 . The CMP wafer carrier of  claim 1  wherein the means for transmitting rotational force comprises an upper yoke and the means for receiving rotational force comprises a lower yoke.  
     
     
         3 . The CMP wafer carrier of  claim 2  further comprising: 
 a plurality of bushings for slidably engaging the spider to the upper yoke and the lower yoke permitting motion of the bushings parallel to the axis or rotation.    
     
     
         4 . The CMP wafer carrier of  claim 1  wherein the means for transmitting load force comprises a plurality of wedges and the means for receiving load force comprises a plurality of ball transfer units, each ball transfer unit including a load ball rotatably disposed within a housing.  
     
     
         5 . The CMP wafer carrier of  claim 1  wherein the means for transmitting load force comprises a plurality of ball transfer units, each ball transfer unit including a load ball rotatably disposed within a housing and the means for receiving load force comprises a plurality of wedges.  
     
     
         6 . A CMP wafer carrier adapted to engage a spindle having an axis of rotation, the wafer carrier comprising: 
 an upper plate coaxially secured to the spindle, the upper plate including an upper yoke for transferring rotational force and a plurality of wedges for transferring load force;    a pressure plate including a lower yoke for transferring rotational force, and a plurality of ball transfer units each ball transfer unit engaging a wedge for transferring load force, each ball transfer unit including a load ball rotatably disposed within a housing; and    a spider engaging the upper yoke and the lower yoke for transferring rotational force.    
     
     
         7 . The CMP wafer carrier of  claim 6  further comprising: 
 a plurality of bushings for slidably engaging the spider to the upper yoke and the lower yoke permitting motion of the bushings parallel to the axis or rotation.    
     
     
         8 . The CMP wafer carrier of  claim 6  wherein each wedge of the plurality of wedges includes a bearing surface for engaging a load ball.  
     
     
         9 . The wafer carrier of  claim 8  wherein the bearing surfaces of the plurality or wedges define a spherical section, and are disposed relative to the load balls so as to restrain movement of the load balls to the spherical section.  
     
     
         10 . The wafer carrier of  claim 9  wherein the bearing surfaces define a spherical section having a center located at the front side of a wafer.  
     
     
         11 . The wafer carrier of  claim 9  wherein the bearing surfaces define a spherical section having a center displaced from the front side of a wafer.  
     
     
         12 . The wafer carrier of  claim 9  wherein the bearing surfaces define a spherical section having a center located outside the front side of a wafer, opposite the pressure plate.