Method for polishing a semiconductor wafer

Abstract

An apparatus for polishing a wafer comprises a supporting portion having an abrasive pad disposed thereon, and a polishing head disposed over the abrasive pad. The polishing head comprises a carrier having at least two fluid passages, a retainer ring disposed on a lower edge of the carrier, forming a space for receiving the wafer, a supporter disposed in the carrier, and a flexible membrane disposed to be in contact with the wafer. The supporter has an upper surface portion, a lower surface portion, a plurality of first holes, a plurality of second holes, and a first chamber. The upper surface portion of the supporter forms a second chamber along with an inner surface of the carrier. The second chamber is in communication with one of the two fluid passages of the carrier and the second holes are formed in a lower surface portion of the supporter to communicate with the second chamber. The first chamber is in communication with the other one of the two fluid passages and the first holes are formed in the lower surface portion of the supporter to communicate with the first chamber. The lower surface portion of the supporter has a flat surface and a chamfered or rounded edge. The membrane disposed to enclose the lower surface portion of the supporter has a plurality of third holes formed at positions corresponding to the first holes to absorb and hold the wafer by vacuum.

1 . A method for polishing a wafer, comprising the steps of: 
 vacuum-absorbing a wafer through a vacuum hole of a membrane positioned under a polishing head;    locating the vacuum-absorbed wafer on a polishing pad; and    polishing the wafer.    
     
     
         2 . The method of  claim 1  wherein vacuum-absorbing comprises drawing a vacuum on a fluid path formed through a supporter of the polishing head on which the membrane is mounted.  
     
     
         3 . The method of  claim 2  wherein the vacuum hole of the membrane comprises multiple first vacuum holes and wherein the supporter includes multiple second vacuum holes in alignment with the multiple first vacuum holes, and wherein the fluid path is in communication with the multiple second vacuum holes.  
     
     
         4 . The method of  claim 3  wherein, during vacuum absorbing, each of the first vacuum holes forms a seal about the corresponding second vacuum hole.  
     
     
         5 . The method of  claim 3  wherein a plurality of film structures are disposed on an outer surface of the supporter about each of the multiple second holes, each of the films mating with the corresponding first vacuum hole formed in the membrane.  
     
     
         6 . An apparatus having a polishing head for polishing a wafer comprising: 
 a carrier;    at least one membrane dividing said carrier to form at least two chambers;    a retainer ring disposed on an edge of said polishing head; and    a chucking ring disposed on a lower portion of said polishing head, the chucking ring including a plurality of holes through which a vacuum is applied such that a wafer in proximity to the membrane is drawn by the vacuum through the holes toward the polishing head;    wherein said polishing head further includes a center supporter disposed in said carrier to provide a first chamber, and a middle supporter disposed in said carrier on the same plane as that of the center supporter, to provide a second chamber;    wherein said membrane is composed of first and second membranes enclosing said center and middle supporters separable from surface portions of said supporters; and    wherein said chucking ring is disposed in said carrier to provide a third chamber and    wherein said chucking ring is disposed between said center supporter and said middle supporter.    
     
     
         7 . An apparatus for polishing a wafer comprising: 
 a supporting portion having an abrasive pad disposed thereon;    a polishing head disposed over said abrasive pad; and    said polishing head comprising: 
 a carrier;  
 at least one membrane dividing said carrier to form at least two chambers;  
 a retainer ring disposed on an edge of said polishing head; and  
 a chucking ring disposed on a lower portion of said polishing head, the chucking ring including a plurality of holes through which a vacuum is applied such that a wafer in proximity to the membrane is drawn by the vacuum through the holes toward the polishing head;  
   wherein said chucking ring is located between a center supporter and a middle supporter disposed in the carrier.