Workpiece edge grinding machine and method

Abstract

A grinding machine for edge grinding the peripheral wafer edge of a semiconductor wafer is configured for conducting an in situ dressing operation to refurbish or dress the peripheral grinding rim surface of a grinding wheel. The grinding machine includes at least one wafer-holding chuck, a grinding wheel, and a dressing tool that are linearly spaced apart and can be respectively moved relative to each other to selectively conduct the grinding and dressing operations. In one form plural grinding stations are disclosed.

1 . An edge grinding module for grinding a peripheral edge of a flat semiconductor wafer comprising:
 a wafer-holding chuck rotatable about a rotational axis for rotatably supporting a semiconductor wafer having a peripheral wafer edge;   a grinding wheel rotatable about a rotational axis having a peripheral grinding rim surface spaced from the wafer-holding chuck; and   a dressing tool having a peripheral dressing face spaced from the peripheral grinding rim surface of the grinding wheel;   wherein one of the wafer-holding chuck and the grinding wheel is movable to contact the peripheral wafer edge of the semiconductor wafer supported on the wafer-holding chuck and the peripheral grinding rim surface in a grinding operation, and one of the grinding wheel and the dressing tool are movable to contact the peripheral grinding rim surface of the grinding wheel and the peripheral dressing face of the dressing tool during a dressing operation.   
     
     
         2 . The edge grinding module of  claim 1 , wherein the dressing tool comprises a dressing wheel having a dressing face profile and is connectable to a rotatable shaft of a dressing tool spindle assembly rotatable about a rotational axis that is parallel to and spaced from the rotational axis of the grinding wheel. 
     
     
         3 . The edge grinding module of  claim 2 , wherein the grinding wheel is connected to a rotatable shaft of a grinding wheel spindle assembly and the wafer-holding chuck is connected to a rotatable shaft of a wafer-holding chuck spindle assembly having a rotational axis, and the rotational axes of the dressing tool spindle assembly and the grinding wheel spindle assembly are aligned along and linearly movable with respect to a linear axis of the edge grinding module. 
     
     
         4 . The edge grinding module of  claim 3 , wherein the wafer-holding chuck spindle assembly and the grinding wheel spindle assembly are respectively and linearly movable to periodically contact the peripheral grinding rim surface and the peripheral edge of a semiconductor wafer supported on the wafer-holding chuck during a grinding operation. 
     
     
         5 . The edge grinding module of  claim 4 , wherein the rotational axis of the wafer-holding chuck spindle assembly, the rotational axis of the grinding wheel spindle assembly, and the rotational axis of the dressing tool spindle assembly are parallel and aligned in a common vertical plane. 
     
     
         6 . The edge grinding module of  claim 5 , wherein the grinding wheel spindle assembly is located linearly between the wafer-holding chuck spindle assembly and the dressing tool spindle assembly. 
     
     
         7 . The edge grinding module of  claim 6 , wherein the wafer-holding chuck, the grinding wheel, and the dressing tool are rotatable in and co-planar with an operational plane of the grinding module. 
     
     
         8 . The edge grinding module of  claim 3 , wherein the peripheral grinding rim surface of the grinding wheel and the peripheral dressing face of the dressing tool are circular and concentric about the respective second rotational axis and the third rotational axis. 
     
     
         9 . The edge grinding module of  claim 8 , wherein the peripheral grinding rim surface includes a plurality of annular grooves or tracks radially disposed therein that are axially spaced with respect to the second rotational axis. 
     
     
         10 . The edge grinding module of  claim 9 , wherein the peripheral dressing face includes a plurality of annular shaping rings radially protruding therefrom that are axially spaced with respect to the rotational axis of the dressing tool spindle assembly and that inversely correspond to the plurality of annular grooves or tracks. 
     
     
         11 . The edge grinding module of  claim 10 , wherein the peripheral dressing face includes a single annular shaping ring radially protruding therefrom. 
     
     
         12 . The edge grinding module of  claim 10 , wherein the dressing tool spindle assembly is vertically movable along the rotational axis to alternatively align the single annular shaping ring with the plurality of annular grooves or tracks of the grinding wheel. 
     
     
         13 . The edge grinding module of  claim 3 , further comprising a module enclosure that accommodates the wafer-holding chuck spindle assembly and the grinding wheel spindle assembly and a dressing station enclosure that accommodates the dressing tool spindle assembly. 
     
     
         14 . The edge grinding module of  claim 13 , wherein the dressing tool spindle assembly is linearly extendable and retractable with respect to the module enclosure. 
     
     
         15 . The edge grinding module of  claim 14 , wherein the module enclosure and the dressing station enclosure are linearly attached and are interconnected by an opening in a common wall through which the dressing tool spindle assembly can traverse. 
     
     
         16 . A method of operation of an edge grinding module for grinding a peripheral edge of a flat semiconductor wafer comprising:
 securing a wafer to a wafer-holding chuck rotationally disposed along a first rotational axis;   rotating a grinding wheel rotationally disposed along a second rotational axis spaced with respect to the wafer-holding chuck;   conducting a grinding operation by moving the wafer-holding chuck or the grinding wheel to contact the peripheral edge of the flat semiconductor wafer and a peripheral grinding rim surface of the grinding wheel; and separately conducting a grinding wheel dressing operation compromising,   locating a dressing tool having a peripheral dressing face adjacent to the grinding wheel; and   conducting the dressing operation by moving the dressing tool or the grinding wheel to contact a peripheral dressing face and the peripheral grinding rim surface.   
     
     
         17 . The method of  claim 16 , wherein the dressing tool is rotationally disposed along a third rotational axis and further comprising the step of rotating the peripheral dressing face in contact with the peripheral grinding rim surface of the grinding wheel. 
     
     
         18 . The method of  claim 17 , wherein the wafer-holding chuck, the peripheral grinding rim surface of the grinding wheel, and the dressing tool are essentially co-planar with an operational plane. 
     
     
         19 . The method of  claim 18 , wherein the grinding wheel includes a plurality of annular grooves or tracks radially disposed in the peripheral grinding rim surface and axially spaced with respect to the second rotational axis. 
     
     
         20 . The method of  claim 19 , wherein the dressing tool include a plurality of annular shaping rings radially disposed on the peripheral dressing face that are axially spaced with respect to the third rotational axis and that inversely correspond to the plurality of annular grooves or tracks. 
     
     
         21 . The method of  claim 20 , further comprising moving the dressing tool with respect to the third rotational axis to vertically align an annular shaping ring radially protruding from the peripheral dressing face to sequentially dress the plurality of annular grooves or tracks. 
     
     
         22 . A grinding machine for automated edge grinding of flat semiconductor wafers comprising:
 a wafer loading station for receiving one or more wafers;   a wafer unloading station for removal of the one or more wafers;   a plurality of edge grinding modules aligned between the wafer loading station and the wafer unloading station, each edge grinding module including a wafer-holding chuck rotationally aligned on a first rotational axis, a grinding wheel rotationally aligned on a second rotational axis, and a dressing tool rotationally aligned a third rotational axis, wherein the wafer-holding chuck, the grinding wheel, and the dressing tool are relatively movable to periodically conduct a grinding operation on the one or more wafers and to separately conduct a dressing operation on the grinding wheel to dress the grinding wheel with the dressing tool; and   a Cartesian robot to transport the one or more wafer between the wafer loading station, the wafer unloading station, and the plurality of edge grinding modules.