Fixed Abrasive Pad Having Different Real Contact Areas and Fabrication Method Thereof

Abstract

Disclosed is a method for fabricating a fixed abrasive pad in use of a chemical mechanical polishing process. The method includes: forming one or more etching molds providing a plurality of different real contact areas; attaching the etching mold(s) to a roller or press; and forming a fixed abrasive pad using the roller or press, The fixed abrasive pad has a plurality of polishing portions, each having a different real contact area. Especially, the fixed abrasive pad can comprise a low-density polishing portion having a real contact area less than 20% and a high-density polishing portion having a real contact area of 20%˜50%.

1 . A fixed abrasive pad, comprising a first polishing portion having a relatively low real contact area and a second polishing portion having a relatively high real contact area. 
   
   
       2 . The fixed abrasive pad of  claim 1 , wherein the low-density polishing portion has a real contact area of less than 20% and the high-density polishing portion has a real contact area of 20%˜50%. 
   
   
       3 . The fixed abrasive pad of  claim 2 , wherein the second polishing portion has a real contact area that is at least 10% greater than a real contact area of the first polishing portion. 
   
   
       4 . The fixed abrasive pad of  claim 1 , adapted for chemical mechanical polishing a wafer using chemical mechanical polishing equipment. 
   
   
       5 . A method for polishing a wafer, comprising the steps of:
 polishing the wafer on a first polishing portion of a fixed abrasive pad comprising a plurality of polishing portions, the first polishing portion having a relatively low real contact area; and   polishing the wafer on a second polishing portion of the fixed abrasive pad, the second polishing portion having a relatively high real contact area.   
   
   
       6 . The method of  claim 5 , wherein the first polishing portion has a real contact area of less than 20% and the second polishing portion has a real contact area of 20%˜50%. 
   
   
       7 . The method of  claim 6 , wherein the second polishing portion has a real contact area that is at least 10% greater than a real contact area of the first polishing portion. 
   
   
       8 . The method of  claim 5 , wherein the wafer has a predetermined pattern thereon. 
   
   
       9 . The method of  claim 5 , comprising polishing the wafer initially on the low real contact area. 
   
   
       10 . The method of  claim 9 , comprising polishing the wafer on the high real contact area after initially polishing the wafer on the low real contact area. 
   
   
       11 . A polishing apparatus, comprising:
 a turn table;   a fixed abrasive pad on the turn table, comprising a first polishing portion having a relatively low real contact area and a second polishing portion having a relatively high real contact area; and   a wafer carrier adapted to hold a wafer and rotate the wafer against the fixed abrasive pad.   
   
   
       12 . The apparatus of  claim 11 , further comprising a chemical supplier over the turn table. 
   
   
       13 . The apparatus of  claim 11 , wherein the first polishing portion has a real contact area of less than 20% and the second polishing portion has a real contact area of 20%˜50%. 
   
   
       14 . The apparatus of  claim 13 , wherein the second polishing portion has a real contact area that is at least 10% greater than a real contact area of the first polishing portion. 
   
   
       15 . An apparatus for making a fixed abrasive pad, comprising:
 one or more etching molds having a first region providing a relatively low real contact area and a second region providing a relatively high real contact area;   a roller or press to which the etching mold(s) are attached, adapted to press an abrasive particle mixture onto a pad base; and   one or more mechanisms for supplying the pad base and the abrasive particle mixture to the roller or press.   
   
   
       16 . The apparatus of  claim 15 , wherein the first region has a real contact area of less than 20% and the second region has a real contact area of 20%˜50% 
   
   
       17 . The apparatus of  claim 15 , further comprising a plurality of etching molds, each etching mold having a different real contact area. 
   
   
       18 . The apparatus of  claim 17 , wherein the etching molds have a surface morphology opposite or complementary to a shape formed on the fixed abrasive pad. 
   
   
       19 . The apparatus of  claim 15 , wherein the roller comprises a plurality of through-holes. 
   
   
       20 . The apparatus of  claim 16 , wherein the second polishing portion has a real contact area that is at least 10% greater than a real contact area of the first polishing portion.