Chemical-mechanical polishing wafer and method of use

Abstract

The present invention is directed to systems and methods for assisting personnel in discerning which side of a dummy wafer has been polished more and for differentiating one side of a dummy wafer from the other. In a preferred embodiment, dummy wafers include a first plurality of depth indicia on a first surface and a second plurality of depth indicia on a second opposing surface. In one embodiment, each of the depth indicia of the first plurality of depth indicia extends a depth into the dummy wafer beyond the first surface, and each of the depth indicia of the second plurality of depth indicia extends a depth into the dummy wafer beyond the second surface. Other embodiments include depth indicia of the first plurality of depth indicia located at depths beyond the first surface that each have a corresponding depth indicia in the second plurality of depth indicia located at a substantially similar depth beyond the second surface. In other embodiments, each of the depth indicia of the first and second pluralities of depth indicia are located at different depths.

1 . A wafer for chemical-mechanical polishing comprising:
 a substrate having a first flat surface, a second flat surface opposing the first flat surface, and a thickness defined between the first and second flat surfaces, wherein each of the first and second flat surfaces exhibit a flatness with a tolerance between approximately 0.0100 of an inch and approximately 0.0040 of an inch,   a first depth indicia borne on the first flat surface, wherein the first depth indicia extends a first depth below the first flat surface;   a second depth indicia borne on the first flat surface, wherein the second depth indicia extends a second depth below the first flat surface and the second depth is greater than the first depth;   a third depth indicia borne on the second flat surface, wherein the third depth indicia extends a third depth below the second flat surface;   a fourth depth indicia borne on the second flat surface, wherein the fourth depth indicia extends a fourth depth below the second flat surface and the fourth depth is greater than the third depth.   
     
     
         2 . A wafer according to  claim 1 , further comprising a side indicia borne on the first flat surface, wherein the side indicia extends a fifth depth below the first flat surface;
 wherein the first depth is less than the fifth depth;   wherein the second depth is equal to or less than the fifth depth;   wherein the third depth is less than the fifth depth; and   wherein the fourth depth is equal to or less than the fifth depth.   
     
     
         3 . A wafer according to  claim 1 , wherein the wafer is made of copper. 
     
     
         4 . A wafer according to  claim 1 , wherein the first depth is substantially equal to the third depth. 
     
     
         5 . A wafer according to  claim 4 , wherein the second depth is substantially equal to the fourth depth. 
     
     
         6 . A wafer according to  claim 1 , wherein:
 the first depth is approximately 0.0004 of an inch;   the second depth is approximately 0.0008 of an inch;   the third depth is approximately 0.0004 of an inch; and   the fourth depth is approximately 0.0008 of an inch.   
     
     
         7 . A wafer according to  claim 1 , wherein:
 the first depth is approximately 0.0004 of an inch;   the second depth is approximately 0.0008 of an inch;   the third depth is approximately 0.0002 of an inch; and   the fourth depth is approximately 0.0006 of an inch.   
     
     
         8 . A wafer according to  claim 1 , wherein:
 the first depth indicia is substantially identical to the third depth indicia; and   the second depth indicia is substantially identical to the fourth depth indicia.   
     
     
         9 . A wafer according to  claim 1 , wherein the thickness is approximately 0.0315 of an inch. 
     
     
         10 . A wafer according to  claim 1 , wherein:
 the first depth indicia borne on the first flat surface is configured to be worn away via polishing before the second depth indicia borne on the first flat surface to indicate a first amount of polishing;   the third depth indicia borne on the second flat surface is configured to be worn away via polishing before the fourth depth indicia borne on the second flat surface to indicate a second amount of polishing;   the second depth indicia borne on the first flat surface is configured to be worn away via polishing to indicate a third amount of polishing; and   the fourth depth indicia borne on the second flat surface is configured to be worn away via polishing to indicate a fourth amount of polishing.   
     
     
         11 . A wafer for chemical-mechanical polishing comprising:
 a substrate having a first flat surface, a second flat surface opposing the first flat surface, and a thickness defined between the first and second flat surfaces, wherein each of the first and second flat surfaces exhibit a flatness with a tolerance between approximately 0.0100 of an inch and approximately 0.0040 of an inch,   a first plurality of depth indicia borne on the first flat surface, wherein each of the first plurality of depth indicia extends a depth below the first flat surface, wherein no two of the first plurality of depth indicia extend the same depth below the first flat surface; and   a second plurality of depth indicia borne on the second flat surface, wherein each of the second plurality of depth indicia extends a depth below the second flat surface, wherein no two of the second plurality of depth indicia extend the same depth below the second flat surface.   
     
     
         12 . A wafer according to  claim 11 , wherein
 the depth for each of the first plurality of depth indicia has a corresponding approximately equal depth in the depths for the second plurality of depth indicia.   
     
     
         13 . A wafer according to  claim 12 , wherein:
 a first indicia for the first plurality of depth indicia extends approximately 0.0004 of an inch below the first surface, and each subsequent indicia for the first plurality of depth indicia extends approximately an additional 0.0004 of an inch below the first surface; and   a first indicia for the second plurality of depth indicia extends approximately 0.0004 of an inch below the second surface, and each subsequent indicia for the second plurality of depth indicia extends approximately an additional 0.0004 of an inch below the second surface.   
     
     
         14 . A wafer according to  claim 11 , wherein:
 each depth for the first plurality of depth indicia is different from each depth for the second plurality of depth indicia.   
     
     
         15 . A wafer according to  claim 14 , wherein:
 a first indicia for the first plurality of depth indicia extends approximately 0.0004 of an inch below the first surface, and each subsequent indicia for the first plurality of depth indicia extends approximately an additional 0.0004 of an inch below the first surface; and   a first indicia for the second plurality of depth indicia extends approximately 0.0002 of an inch below the second surface, and each subsequent indicia for the second plurality of depth indicia extends approximately an additional 0.0004 of an inch below the second surface.   
     
     
         16 . A wafer according to  claim 11 , wherein the wafer is made of copper. 
     
     
         17 . A wafer according to  claim 11 , further comprising a side indicia borne on the first flat surface, wherein the side indicia extends a depth below the first flat surface that is greater than a maximum depth for an indicia of the first plurality of depth indicia. 
     
     
         18 . A wafer for chemical-mechanical polishing comprising:
 a substrate means having a first flat surface and a second flat surface for being chemically-mechanically polished;   a first depth indicating means for indicating an amount of wear occurring on the first surface; and   a second depth indicating means for indicating an amount of wear occurring on the second surface.   
     
     
         19 . A wafer according to  claim 18 , further comprising:
 a side indicating means for differentiating the first flat surface from the second flat surface.