Abstract:
Provided is a method of manufacturing a wafer carrier capable of providing good abrasion resistance to remarkably increase lifespan of the wafer carrier, and preventing occurrence of defects from an edge of a wafer during double-sided polishing of the wafer. The method includes machining a carrier body constituting the wafer carrier in a pre-set shape, forming a preliminary hole and a slurry introduction hole in the carrier body of the wafer carrier, coating diamond-like carbon (DLC) on the carrier body having the preliminary hole, and, after coating the DLC, enlarging the preliminary hole to form a wafer retaining hole, into which the wafer is inserted.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims the benefit of Korean Patent Application No. 10-2007-0122655, filed 29 Nov. 2007, the disclosure of which is hereby incorporated herein by reference in its entirety. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to a method of manufacturing a wafer carrier, and more particularly, to a method of manufacturing a wafer carrier installed at a double-sided polishing apparatus for polishing both surfaces of a wafer, into which the wafer is inserted in double-sided polishing the wafer. 
         [0004]    2. Description of the Prior Art 
         [0005]    When polishing both surfaces of a wafer, a double-sided polishing apparatus as shown in  FIGS. 1 and 2  is used. Referring to  FIGS. 1 and 2 , a conventional polishing apparatus  9  includes an upper plate  1  and a lower plate  3 , which rotate in opposite directions. Polishing pads  2  and  4  are attached on a lower surface of the upper plate  1  and an upper surface of the lower plate  3  to polish upper and lower surfaces of a wafer w, respectively. In addition, a plurality of wafer carriers  5  are supported and mounted between the upper plate  1  and the lower plate  3  as shown in  FIG. 2 . Each of the wafer carriers  5 , which has a disc shape, includes a wafer retaining hole  6  in which the wafer w is inserted and retained, and five slurry introduction holes  8  disposed around the wafer retaining hole  6  and having different sizes from each other. 
         [0006]    Meanwhile, in recent times, in order to increase abrasion resistance of the wafer carrier  5 , the wafer carrier  5  has been coated with diamond-like carbon (DLC). 
         [0007]    However, as shown in  FIG. 3 , since the wafer carrier is coated with DLC to an inner surface of the wafer retaining hole formed therein, an edge of the wafer may contact the DLC coating layer during double-sided polishing of the wafer. Therefore, the edge of the wafer may be damaged by the DLC coating layer to cause defects of the wafer. 
       SUMMARY OF THE INVENTION 
       [0008]    An aspect of the present invention is to provide a method of manufacturing an improved wafer carrier capable of providing good abrasion resistance to remarkably increase lifespan of the carrier and preventing occurrence of defects to an edge of a wafer during double-sided polishing of the wafer. 
         [0009]    An embodiment of the invention provides a method of manufacturing a wafer carrier, which is installed at a double-sided polishing apparatus for polishing both surfaces of a wafer, the method including: machining a carrier body constituting the wafer carrier in a pre-set shape; forming a preliminary hole and a slurry introduction hole in the carrier body of the wafer carrier; coating diamond-like carbon (DLC) on the carrier body having the preliminary hole; and, after coating the DLC, enlarging the preliminary hole to form a wafer retaining hole, into which the wafer is inserted. 
         [0010]    In accordance with the present invention, the method may further include, after forming the preliminary hole and before coating the DLC, attaching mark members to at least one of a front surface and a rear surface of the carrier body such that the members are spaced apart the same distance from a center point of the preliminary hole. At this time, at least four mark members may be radially disposed about a center point of the preliminary hole. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    The above and other objects, features and advantages of the present invention will be more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which: 
           [0012]      FIG. 1  is a schematic view of a conventional wafer carrier; 
           [0013]      FIG. 2  is a plan view of the conventional wafer carrier shown in  FIG. 1 , in which a plurality of wafer carriers are mounted on a lower plate; 
           [0014]      FIG. 3  is a schematic cross-sectional view taken along line III-III of  FIG. 2 ; 
           [0015]      FIG. 4  is a flowchart showing a method of manufacturing a wafer carrier in accordance with an exemplary embodiment of the present invention; 
           [0016]      FIG. 5  is a plan view of a wafer carrier body, showing mark members shown in  FIG. 4 ; and 
           [0017]      FIG. 6  is a schematic cross-sectional view taken along line VI-VI of  FIG. 5 , showing a wafer carrier having a DLC coating layer. 
       
    
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
       [0018]    Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings. 
         [0019]      FIG. 4  is a flowchart showing a method of manufacturing a wafer carrier in accordance with an exemplary embodiment of the present invention,  FIG. 5  is a plan view of a wafer carrier body, showing mark members shown in  FIG. 4 , and  FIG. 6  is a schematic cross-sectional view taken along line VI-VI of  FIG. 5 , showing a wafer carrier having a DLC coating layer. 
         [0020]    Referring to  FIGS. 4 to 6 , a method of manufacturing a wafer carrier in accordance with an exemplary embodiment of the present invention is for the purpose of manufacturing a wafer carrier installed at the double-sided polishing apparatus described in Description of the Prior art. The method of manufacturing a wafer carrier includes a machining step S 110 , a forming step S 120 , a lapping step S 130 , an attachment step S 150 , a coating step S 160 , and a wafer retaining hole forming step S 170 , which are sequentially performed. 
         [0021]    In the machining step  110 , a carrier body  11  constituting a wafer carrier  10  is machined in a pre-set shape. Here, the carrier body  11  is generally formed of an epoxy glass plate. In addition, epoxy glass is routed in a pre-set shape, for example, a circular shape, to form the carrier body  11  of the wafer carrier. 
         [0022]    In the forming step S 120 , a single preliminary hole  111   a  and a plurality of slurry introduction holes  112  are formed in the routed carrier body  11 . The preliminary hole  111   a  has a diameter smaller than that of a wafer retaining hole  111 , which will be described. For example, when the wafer retaining hole  111  has a diameter of 300 mm, the preliminary hole  111   a  may have a diameter of 290 mm or less. 
         [0023]    In the lapping step S 130 , the carrier body  11  is lapped using a lapping agent. After the lapping step is completed, the carrier body  11  is cleaned (S 140 ). 
         [0024]    In the attachment step S 150 , mark members  20  are attached to the carrier body  11  having the preliminary hole  111   a.  The mark members  20  may be formed of any material attachable to the carrier body  11 . In general, for the mark members  20 , a tape, which is inexpensive and readily available, may be used. The mark members  20  are attached to at least one surface of front and rear surfaces of the carrier body  11 , and, in this embodiment in particular, four mark members  20  are attached to the front surface of the carrier body  11 . Centers of the mark members  20  are spaced apart the same distance from a center point of the preliminary hole  111   a.  Therefore, the four mark members  20  are radially disposed about the center point of the preliminary hole  111   a.  In addition, one edge of the edges of each mark member far from the center point of the preliminary hole  111   a  has an arc shape. In particular, arc-shaped edges of the four mark members  20  form portions of one circumference. At this time, when the mark members  20  are set to an appropriate size, the edges of the mark members  20  are connected to each other such that the connected circle becomes the wafer retaining hole  111 , which will be described. 
         [0025]    In the coating step S 160 , DLC is coated on the carrier body  11 , to which the mark members  20  are attached, to form a DLC coating layer  12 . The DLC coating layer  12  is formed on the mark members  20  as well as the carrier body  11 . The DLC coating layer  12  is formed by a generally known deposition method such as a sputtering method. 
         [0026]    In the wafer retaining hole forming step S 170 , a wafer retaining hole  111  is formed in the carrier body  11  on which the DLC coating layer  12  is formed. That is, the preliminary hole  111   a  is enlarged to form the wafer retaining hole  111  having the same center point as the preliminary hole  111   a.  At this time, the preliminary hole  111   a  is enlarged until the mark members  20  are entirely removed. In particular, when the preliminary hole  111   a  is enlarged until the mark members  20  are removed to the arc-shaped edges, it is possible to form the wafer retaining hole  111  having a desired diameter. As described above, when the preliminary hole  111   a  is enlarged, as shown in  FIG. 6 , there is no DLC coating layer on an inner surface of the wafer retaining hole  111 . After the enlargement of the preliminary hole  111   a,  a cleaning step S 180  is performed. 
         [0027]    As described above, when the method of manufacturing a wafer carrier of the embodiment is used, since the DLC coating layer  12  is not formed on the inner surface of the wafer retaining hole  111  of the wafer carrier, it is possible, unlike the conventional art, to prevent damage to an edge of the wafer w during double-sided polishing of the wafer w. Therefore, it is possible, unlike the conventional art, to improve abrasion resistance of the wafer carrier  10  using the DLC coating layer and prevent damage to the wafer during double-sided polishing of the wafer w, thereby improving quality of the wafer. In addition, lifespan of the wafer carrier can be remarkably increased. 
         [0028]    In particular, when arc-shaped edges of the four mark members are connected to each other to form the wafer retaining hole, it is possible to readily form the wafer retaining hole by enlarging the preliminary hole to the edges of the mark members  20  without measuring the dimension of the enlargement. 
         [0029]    While an exemplary embodiment in accordance with the present invention has been described, the present invention not being limited thereto, it will be apparent to those skilled in the art that various modifications may be made without departing from the technical spirit of the present invention. 
         [0030]    For example, while the embodiment has been described to include attaching the mark members, but not limited thereto, the preliminary hole may be enlarged just after coating the DLC to form the wafer retaining hole, without attaching the mark members. 
         [0031]    In addition, while the embodiment has been described such that the edges of the mark members form portions of arcs, the edges of the mark members need not be used to form the portions of the arcs. That is, after forming the mark members in a polygon such as a square, an imaginary straight line from an apex of the mark member to a center of the preliminary hole may be set as a radius of the wafer retaining hole such that the preliminary hole is enlarged. 
         [0032]    As can be seen from the foregoing, since a wafer carrier is coated with DLC having good abrasion resistance, it is possible to remarkably increase lifespan of the wafer carrier. In addition, since the DLC coating layer is not formed on an inner surface of a wafer retaining hole of the wafer carrier, it is possible to prevent damage to an edge of the wafer due to contact with the DLC coating layer during double-sided polishing of the wafer. 
         [0033]    While this invention has been described with reference to exemplary embodiments thereof, it will be clear to those of ordinary skill in the art to which the invention pertains that various modifications may be made to the described embodiments without departing from the spirit and scope of the invention as defined in the appended claims and their equivalents.