Silicon Wafer Grinding Apparatus, Retaining Assembly Used for the Same and Silicon Wafer Flatness Correcting Method

Abstract

A silicon wafer grinding apparatus, a retaining assembly used for the same, and a silicon wafer flatness correcting method are provided More particularly, a silicon wafer grinding apparatus, a retaining assembly used for the same, and a silicon wafer flatness correcting method for correcting a wafer flatness in a final grinding process are provided The silicon wafer grinding apparatus includes a grinding surface plate having a grinding pad attached thereon; a grinding head arranged opposite to the grinding surface plate and rotated in the same direction as that of the grinding surface plate; a backing film attached at a lower portion of the grinding head for supporting a wafer; and a retainer ring having an inner diameter (a wafer diameter +α) greater than a diameter of the wafer by as much as a and disposed on the backing film. By forming a diameter or physical properties of a part of the backing film of the wafer retaining assembly, the wafer flatness of the final grinding may be corrected.

1 . A silicon wafer grinding apparatus comprising: 
 a grinding surface plate having a grinding pad attached thereon;    a grinding head arranged opposite to the grinding surface plate and rotated in the same direction as that of the grinding surface plate;    a backing film attached at a lower portion of the grinding head for supporting a wafer; and    a retainer ring disposed in the backing film and having an inner diameter greater than a diameter of a wafer contained therein.    
     
     
         2 . The silicon wafer grinding apparatus of  claim 1 , wherein the backing film has a uniform thickness and had an edge portion adjacent to the retaining ring that is formed from a soft material.  
     
     
         3 . The silicon wafer grinding apparatus of  claim 2 , wherein the edge portion has a width of about from about 3 to about 5 mm in an inner radial direction from an inner wall of the retainer ring.  
     
     
         4 . The silicon wafer grinding apparatus of  claim 2 , wherein the edge portion has a width of less than about 2% of an inner diameter of the retainer ring.  
     
     
         5 . The silicon wafer grinding apparatus of  claim 1 , wherein the backing film is formed of one material but has a non-uniform thickness.  
     
     
         6 . The silicon wafer grinding apparatus of  claim 5 , wherein when the backing film is formed of one material and has an edge portion near the retaining ring that is thicker than a center portion further away form the retainer ring.  
     
     
         7 . The silicon wafer grinding apparatus of  claim 5 , wherein the backing film is formed of one material, the backing film includes an edge portion having a predetermined width near the retaining ring and at least one land portion having a predetermined height stepped in a radial direction from the edge portion.  
     
     
         8 . The silicon wafer grinding apparatus of  claim 7 , wherein the edge portion has a width of from about 3 to about 5 mm in an inner radial direction from an inner wall of the retainer ring.  
     
     
         9 . The silicon wafer grinding apparatus of  claim 7 , wherein the edge portion has a width of less than about 2% of an inner diameter of the retainer ring.  
     
     
         10 . The silicon wafer grinding apparatus of  claim 1 , wherein the backing film is formed of one material and includes at least one groove portion along a circumference direction.  
     
     
         11 . The silicon wafer grinding apparatus of  claim 10 , wherein the backing film includes an edge portion along a circumference direction and near the inner wall of the retaining ring, and a land portion having a predetermined height surrounded by the groove portion.  
     
     
         12 . The silicon wafer grinding apparatus of  claim 11 , wherein the edge portion has a width of from about 3 to about 5 mm in an inner radial direction from an inner wall of the retainer ring.  
     
     
         13 . The silicon wafer grinding apparatus of  claim 11 , wherein the edge portion has a width of less than about 2% of an inner diameter of the retainer ring.  
     
     
         14 . A wafer flatness correcting method comprising: 
 marking a center of a grinding head;    attaching a first backing film to a grinding head, disposing a retainer ring having an inner diameter greater than a diameter of a sample wafer on the first backing film;    placing a sample wafer in the retainer ring and performing final grinding;    measuring flatness of the finally ground sample wafer;    manufacturing a heterogeneous second backing film according to the measured sample wafer flatness; and    finally grinding actual wafers of the same diameter as the sample wafer using the second backing film.    
     
     
         15 . The wafer flatness correcting method of  claim 14 , wherein the manufacturing of a heterogeneous second backing film includes sequentially forming a part of at least one of a foaming layer, a substrate layer, and a pressure sensitive adhesive layer with different materials.  
     
     
         16 . The wafer flatness correcting method of  claim 14 , wherein the manufacturing of a heterogeneous second backing film includes sequentially forming a part of at least one of a foaming layer, a substrate layer, and a pressure sensitive adhesive layer to have a different thickness.  
     
     
         17 . The wafer flatness correcting method of  claim 14 , wherein the forming the secondary backing film includes removing a portion of the first backing film corresponding to a portion to correct a flatness of the wafer, aligning and attaching the center marking of the secondary backing film to the center of the first backing film.  
     
     
         18 . The wafer flatness correcting method of  claim 14 , wherein the forming the secondary backing film includes removing or attaching at least one of the substrate layer of the first backing film and the foaming layer formed on the substrate layer.  
     
     
         19 . A wafer having a GBIR in a range of from about 0.2 to about 0.5, an SBIR of less than 0.3, and an SFQR in a range of from about 0.13 to about 0.18 based on E. E. 2 mm after final grinding.  
     
     
         20 . A wafer having a GBIR in a range of from about 0.2 to about 0.4, an SBIR in a range of from about 0.15 to about 0.3, and an SFQR in a range of from about 0.1 to about 0.13 based on E. E. 3 mm after final grinding.  
     
     
         21 . A wafer retaining assembly comprising: 
 a circular retainer ring having an inner diameter greater than a wafer diameter, the retainer ring also having an outer diameter and a backing film including a pressure sensitive adhesive layer attached at a lower portion of the grinding head,    a substrate layer formed on the pressure sensitive adhesive layer, a foaming layer formed on the substrate layer, which may be partly attached or detached, and an alignment mark marked at a center thereof.    
     
     
         22 . The wafer retaining assembly of  claim 21 , wherein the backing film further includes a cutting line for detaching at least one of the substrate layer and the foaming layer along a circumference direction.  
     
     
         23 . The wafer retaining assembly of  claim 22 , wherein the backing film further includes a cutting line for detaching all of the substrate layer and the foaming layer along a circumference direction.  
     
     
         24 . The wafer retaining assembly of  claim 22 , wherein the cutting line is formed at a predetermined interval of at least about 3 mm to about 5 mm from an inner wall of the retainer ring.  
     
     
         25 . The wafer retaining assembly of  claim 22 , wherein the cutting line is formed at an external periphery corresponding to about 40% of a radius of the backing film.  
     
     
         26 . The wafer retaining assembly of  claim 21 , wherein the backing film includes a groove portion along a circumference direction at a predetermined distance from the center thereof.  
     
     
         27 . The wafer retaining assembly of  claim 21 , wherein the groove portion has a width of from about 3 to about 5 mm from the inner wall of the retainer ring.  
     
     
         28 . The wafer retaining assembly of  claim 27 , wherein the groove portion has a width of less than about 2% to an inner diameter of the retainer ring.  
     
     
         29 . The wafer retaining assembly of  claim 21 , wherein at least one of the substrate layer, the foaming layer, and the pressure sensitive adhesive layer is formed with a different material than the other of the substrate layer, the foaming layer, and the pressure sensitive adhesive layer.  
     
     
         30 . The wafer retaining assembly of  claim 21 , wherein at least one of the substrate layer, the foaming layer, and the pressure sensitive adhesive layer has a different thickness than the other of the substrate layer, the foaming layer, and the pressure sensitive adhesive layer.