Method and apparatus for two-part CMP retaining ring

Abstract

A two piece retaining ring used for chemical mechanical polishing of semiconductor substrates comprising a relatively rigid upper portion and a less rigid lower portion. The two pieces of the ring are secured to each other by snapping a central channel and extending arms over a central neck extension of the upper part.

1 . A retaining ring for a carrier head, the retaining ring comprising: 
 a first rigid annular portion comprising a downwardly extending annular central neck portion;    a second annular portion of a less rigid material than the first portion, the second portion comprising a central upwardly facing channel; and    a snap connection means such that the central upwardly facing channel of the second annular portion may be snapped over the downwardly extending annular central neck portion of the first rigid annular portion.    
     
     
         2 . The retaining ring of  claim 1  further comprising 
 a rotation prevention means which prevents the second annular portion from rotating with respect to the first rigid annular portion.    
     
     
         3 . The retaining ring of  claim 1  further comprising 
 a vibration reduction means between the second annular portion and the first rigid annular portion.    
     
     
         4 . The retaining ring of  claim 1  wherein 
 the snap connection means is at least one lip on the second annular portion which fits into an annular slot on the first rigid annular portion.    
     
     
         5 . A retaining ring for a carrier head, the retaining ring comprising: 
 a first rigid annular portion comprising 
 a downwardly extending annular central neck portion having a first wall surface toward the center of the retaining ring and a second wall surface away from the center of the retaining ring,  
 a first annular inset in the upper portion of the first wall surface, and  
 a second annular inset in the upper portion of the second wall surface; and  
   a second annular portion of a less rigid material than the first portion, the second portion comprising 
 a central upwardly facing channel having a third wall toward the center of the retaining ring and a fourth wall away from the center of the retaining ring,  
 a first lip in the upper portion of the third wall, and  
 a second lip in the upper portion of the fourth wall, such that the downwardly extending annular central neck portion of the first rigid annular portion nests in the central upwardly facing channel of the second annular portion, and the first lip engages the first annular inset, and such that the second lip engages the second annular inset.  
   
     
     
         6 . A retaining ring for a carrier head, the retaining ring comprising: 
 a first rigid annular portion comprising 
 an upper mounting surface, such that the upper mounting surface may be removable affixed to the carrier head,  
 a lower mating surface,  
 an inside surface toward the center of the retaining ring between the lower mating surface and the upper mounting surface,  
 an annular inset in the upper portion of the inside surface,  
 an outside surface away from the center of the retaining ring between the lower mating surface and the upper mounting surface, and  
 an annular inset in the upper portion of the outside surface;  
   a second annular portion of a less rigid material than the first portion, the second portion comprising 
 a lower wear surface,  
 an upper mating surface, such that the upper mating surface engages the lower mating surface of the first rigid annular portion,  
 an inside wall extending upwardly from the upper mating surface, the inside wall comprising 
 an outside surface away from the center of the retaining ring, and  
 a lip in the upper portion of the outside surface, such that the lip engages the annular inset in the upper portion of the inside surface of the first rigid annular portion, and  
 
 an outside wall extending upwardly from the upper mating surface, the outside wall comprising 
 an inside surface toward the center of the retaining ring, and  
 a lip in the upper portion of the inside surface, such that the lip engages the annular inset in the upper portion of the outside surface of the first rigid annular portion.  
 
   
     
     
         7 . The retaining ring of  claim 6  further comprising 
 a beveled edge between the lower mating surface and the lower portion of the outside surface of the first rigid annular portion; and    a beveled edge between the upper mating surface and the lower portion of the inside surface of the outside wall of the second annular portion.    
     
     
         8 . The retaining ring of  claim 7  further comprising 
 a beveled edge between the lower mating surface and the lower portion of the inside surface of the first rigid annular portion; and    a beveled edge between the upper mating surface and the lower portion of the outside surface of the inside wall of the second annular portion.    
     
     
         9 . A method of assembling the second annular portion onto the first rigid annular portion, the method comprising 
 providing a fixture comprising 
 a top plate having a plurality of alignment holes, and  
 a bottom plate having a plurality of dowel pins inserted into alignment holes, such that a spring is inserted over each dowel pin, the bottom plate including a recess for accepting the second annular portion of the retaining ring;  
   placing the second annular portion in the recess of the bottom plate;    positioning the first rigid annular portion over the second annular portion;    placing the top plate over the dowel pins; and    applying a downward force to the top plate, thereby driving the neck of the first rigid annular portion into the channel of the second annular portion.    
     
     
         10 . A method of removing the second annular portion from the first rigid annular portion, the method comprising 
 inserting a plurality of screws into the mounting holes on the first rigid annular portion;    alternately tightening the screws thereby forcing the second annular portion away from the first rigid annular portion.