Plasma reactor gas distribution plate with radially distributed path splitting manifold

Abstract

In a showerhead assembly, a path splitting manifold comprises a gas supply inlet and a planar floor and plural gas outlets extending axially through the floor and azimuthally distributed about the floor. The path splitting manifold further comprises a plurality of channels comprising plural paths between the inlet and respective ones of the plural outlets. A gas distribution showerhead underlies the floor of the manifold and is open to the plural outlets. In certain embodiments, the plural paths are of equal lengths.

What is claimed is: 
     
         1 . A gas distribution showerhead assembly for use in a plasma reactor, comprising:
 a gas supply lid having a bottom surface, and a gas supply port in said bottom surface;   a manifold plate having top and bottom manifold surfaces, said top manifold surface facing said bottom surface of said gas supply lid;   a showerhead plate facing said bottom manifold surface and an array of plural gas injection orifices extending through said showerhead plate and distributed in both a radial direction and in an azimuthal direction;   a gas distribution manifold comprising:
 (a) plural manifold orifices extending through said manifold plate and located along a radial location; 
 (b) plural top surface channels in said top manifold surface and defining plural top paths of generally equal lengths between said gas supply port and respective ones of said manifold orifices; 
 (c) plural bottom surface channels formed in said bottom manifold surface and defining plural bottom paths of generally equal lengths between respective ones of said manifold orifices and respective ones of said plural gas injection orifices. 
   
     
     
         2 . The apparatus of  claim 1  wherein said plural top surface channels constitute a hierarchy of channels recursively coupled at their midpoints to outputs of other channels of said hierarchy. 
     
     
         3 . The apparatus of  claim 2  wherein said plural bottom surface channels comprise plural arcuate bottom surface channels at respective radial locations and plural radial bottom surface channels extending between respective ones of said arcuate bottom surface channels, each of said radial bottom surface channels having a midpoint in registration with a respective one of said manifold orifices. 
     
     
         4 . The apparatus of  claim 3  wherein said arcuate bottom surface channels are terminated at respective zones in registration with respective ones of said plural gas injection orifices of said zone. 
     
     
         5 . The apparatus of  claim 4  wherein said plural arcuate bottom surface channels comprise four sections of said arcuate bottom surface channels, each of said arcuate bottom surface channels extending one quarter of an arc circle between corresponding pairs of said respective zones. 
     
     
         6 . The apparatus of  claim 1  wherein said top surface channels provide gas distribution in an azimuthal direction and said bottom surface channels provide gas distribution in both radial and azimuthal directions. 
     
     
         7 . The apparatus of  claim 6  wherein said plural bottom paths between respective ones of said manifold orifices and respective ones of the plural gas injection orifices of said zone are of generally equal lengths.