Electron beam plasma source with profiled chamber wall for uniform plasma generation

Abstract

A plasma reactor that generates plasma in a workplace processing chamber by an electron beam, has an electron beam source chamber with a wall opposite to the electron beam propagation direction, the wall being profiled to compensate for a non-uniformity in electron beam density distribution.

What is claimed is: 
     
         1 . A plasma reactor for processing a workpiece, comprising:
 a workpiece processing chamber having a processing chamber comprising a chamber ceiling and a chamber side wall and an electron beam opening in said chamber side wall, a workpiece support pedestal in said processing chamber having a workpiece support surface facing said chamber ceiling and defining a workpiece processing region between said workpiece support surface and said chamber ceiling, said electron beam opening facing said workpiece processing region;   an electron beam, source chamber comprising a source enclosure, said source enclosure having an electron beam emission window that is open to said electron beam opening of said workpiece processing chamber, and defining an electron beam propagation path along a longitudinal direction extending through said electron beam emission window and through said electron beam opening and into said workpiece processing region, said source enclosure further comprising a back wall displaced from said electron beam emission window by a gap along said longitudinal direction, said electron beam emission window extending generally along a direction transverse to said longitudinal direction;   an electron beam extraction grid, across said electron beam emission window, an extraction voltage source coupled to said electron beam extraction grid, and the said electron beam source chamber; and   said back wall having a profile corresponding to a distribution of said gap along said transverse direction.   
     
     
         2 . The plasma reactor of  claim 1  wherein said distribution of said gap corresponds to a distribution in electron beam density along said transverse direction. 
     
     
         3 . The plasma reactor of  claim 1  wherein said distribution of said gap along said transverse direction corresponds to a measured distribution in electron beam density distribution along said transverse direction. 
     
     
         4 . The plasma reactor of  claim 1  wherein said distribution of said gap along said transverse direction is center-low, wherein said gap has a minimum value at a center location of said back wall along said transverse direction. 
     
     
         5 . The plasma reactor of  claim 4  wherein said distribution of said gap along said transverse direction of said electron beam source chamber compensates for a measured distribution of plasma density along said transverse direction that is center-high. 
     
     
         6 . The plasma reactor of  claim 1  wherein said distribution of said gap along said transverse direction is center-high, wherein said gap has a maximum value at a center location of said back wall along said transverse direction. 
     
     
         7 . The plasma reactor of  claim 6  wherein said distribution of said gap along said transverse direction of said electron beam source chamber compensates for a measured distribution of plasma, density distribution along said transverse direction that is center-low. 
     
     
         8 . The plasma reactor of  claim 1  wherein said, distribution of said gap along said transverse direction has a variance of least 1%. 
     
     
         9 . The plasma reactor of  claim 1  wherein said distribution of said gap along said transverse direction has a variance of at least 5%. 
     
     
         10 . The plasma reactor of  claim 1  wherein back wall is configurable for changing said profile. 
     
     
         11 . The plasma reactor of  claim 1  wherein said back wall comprises a flexible member capable of deforming between different curvatures, and an actuator coupled to said flexible member. 
     
     
         12 . The plasma reactor of  claim 11  wherein said different curvatures comprise a curvature corresponding to a concave profile or a curvature corresponding to a convex profile. 
     
     
         13 . The plasma reactor of  claim 1  wherein said source enclosure further comprises a ceiling, a floor facing said ceiling, plural elongate slots in one of said floor and ceiling, said slots spaced apart from one another and at least some of said slots extending in different directions relative to said transverse and longitudinal directions, and plural slats removably inserted into selected ones of said slots to form respective barriers extending from said floor to said ceiling and through the selected, slots, said back wall comprising the slats inserted through said slots. 
     
     
         14 . The plasma reactor of  claim 13  wherein said selected slots comprises a set of said plural slots corresponding to one of plural profiles. 
     
     
         15 . The plasma reactor of  claim 14  wherein said plural profiles comprise a convex profile or a concave profile. 
     
     
         16 . The plasma reactor of  claim 14  wherein said plural profile corresponds to a measured distribution in electron beam density distribution along said transverse direction. 
     
     
         17 . The plasma reactor of  claim 11  wherein said different curvatures comprise a curvature corresponding to a measured distribution in electron beam density distribution along said transverse direction. 
     
     
         18 . The plasma reactor of  claim 1  further comprising:
 an electron beam acceleration grid or slot separated by a dielectric from the said electron beam extraction grid, an acceleration voltage source coupled to said electron beam acceleration grid or slot, and the said extraction grid.