E-beam plasma source with profiled e-beam extraction grid for uniform plasma generation

Abstract

A plasma, reactor that relies on an electron beam as a plasma source employs a profiled electron beam extraction grid in an electron beam source to improve uniformity.

What is claimed is: 
     
         1 . A plasma reactor for processing a workpiece, comprising:
 a workpiece processing chamber having a processing chamber enclosure comprising a ceiling and a side wall and an electron beam opening in said side wall, a workpiece support pedestal in said processing chamber having a workpiece support surface facing said ceiling and defining a workpiece processing region between said workpiece support surface and said ceiling, said electron beam opening facing said workpiece processing region;   an electron beam source chamber comprising an electron beam source chamber enclosure and. an emission opening between said electron beam source chamber and said workpiece processing chamber facing said electron beam opening; and   a profiled grid in said emission opening and comprising plural grid, openings each extending through said profiled grid, said grid openings having a non-uniform distribution of a number of grid openings per unit length along an axis parallel with a plane of said workpiece support surface.   
     
     
         2 . The plasma reactor of  claim 1  wherein said non-uniform distribution of said grid openings is a decreasing function of a proximity of said, grid openings to an edge of said profiled grid along said axis. 
     
     
         3 . The plasma reactor of  claim 1  wherein said non-uniform distribution of said, grid openings is an increasing function of a proximity of said grid openings to an edge of said profiled grid along said axis. 
     
     
         4 . The plasma reactor of  claim 1  wherein said grid openings are arranged in regular row and columns, said columns being distributed along said axis, said rows extending parallel to said axis, wherein the number of grid openings in each said column varies with location of each column along said axis. 
     
     
         5 . The plasma reactor of  claim 1  further comprising a voltage source coupled to said profiled grid, said profiled grid comprising a conductive material. 
     
     
         6 . The plasma reactor of  claim 1  wherein said non-uniform distribution of a number of grid openings per unit length is complementary relative to a non-uniformity in plasma distribution along said axis in said electron beam source chamber. 
     
     
         7 . The plasma reactor of  claim 1  further comprising:
 an electron beam source gas supply coupled to said electron beam source chamber; 
 a workpiece process gas supply coupled to said workpiece processing chamber; 
 a supply of plasma source power coupled to said electron beam source chamber; and 
 an electron beam extraction voltage supply coupled to said profiled grid. 
 
     
     
         8 . The plasma reactor of  claim 7  wherein said profiled grid comprises an extraction grid and said grid openings comprises extraction grid openings, said plasma reactor further comprising an acceleration grid in said emission opening and located between said extraction grid and said workpiece processing chamber. 
     
     
         9 . The plasma reactor of  claim 8  wherein said acceleration grid comprises plural acceleration grid openings having a non-uniform distribution of a number of grid openings per unit length along said axis parallel with a plane of said workpiece support surface. 
     
     
         10 . The plasma reactor of  claim 9  wherein said non-uniform distribution of said acceleration grid openings conforms with the non-uniform distribution of said extraction grid openings. 
     
     
         11 . The plasma reactor of  claim 1  wherein said emission opening is located on one side of said workpiece processing chamber, said plasma reactor further comprising:
 a beam dump at a side of said workpiece processing chamber opposite said one side, said beam dump comprising a conductor electrically coupled to a potential attractive to an electron beam. 
 
     
     
         12 . The plasma reactor of  claim 11  wherein said beam dump is electrically coupled to said processing chamber enclosure. 
     
     
         13 . The plasma reactor of  claim 1  wherein said profiled extraction grid comprises one of:
 (a) a conductive sheet having said grid openings formed therethrough; or 
 (b) a conductive mesh. 
 
     
     
         14 . For use in a plasma reactor that includes a workpiece processing chamber having a workpiece support pedestal in said processing chamber with a workpiece support surface, an electron beam source chamber coupled to said workpiece processing chamber through a chamber-to-chamber opening:
 a profiled extraction grid adapted for placement in said chamber-to-chamber opening and comprising plural grid openings, each of said grid openings extending through said profiled extraction grid, said grid openings having a non-uniform distribution of a number of grid openings per unit length along an axis parallel with a plane of said workpiece support surface.   
     
     
         15 . The profiled extraction grid of  claim 14  wherein said non-uniform distribution of said grid openings is a decreasing function of a proximity of said grid openings to an edge of said profiled extraction grid along said axis. 
     
     
         16 . The profiled extraction grid of  claim 14  wherein said non-uniform distribution of said grid openings is an increasing function of a proximity of said grid openings to an edge of said profiled extraction grid along said axis. 
     
     
         17 . The profiled extraction grid of  claim 14  wherein said grid openings are arranged in regular row and columns, said columns being distributed along said axis, said, rows extending parallel to said, axis, wherein the number of grid openings in each said column varies with location of each column along said axis. 
     
     
         18 . A plasma reactor comprising:
 a workpiece processing chamber having a workpiece support pedestal in said processing chamber with a workpiece support surface;   an electron beam source chamber and a supply of plasma source power coupled to said electron beam source chamber;   a chamber-to-chamber opening between said workpiece processing chamber and said electron beam source chamber; and   a profiled extraction grid in said chamber-to-chamber opening and comprising plural grid openings, each of said grid openings extending through said profiled extraction grid, said grid openings having a non-uniform distribution of a number of grid openings per unit length along an axis parallel with a plane of said workpiece support surface; and   a beam extraction voltage supply coupled to said profiled extraction grid.   
     
     
         19 . The plasma reactor of  claim 18  wherein said non-uniform distribution of said grid openings is a decreasing function of a proximity of said grid openings to an edge of said profiled extraction grid along said axis. 
     
     
         20 . The plasma reactor of  claim 18  wherein said non-uniform distribution of said grid openings is an increasing function of a proximity of said grid openings to an edge of said profiled extraction grid along said axis.