Plasma reactor gas distribution plate having a path splitting manifold immersed within a showerhead

Abstract

A showerhead of a plasma reactor has an internal plenum comprising a showerhead floor and a plurality of gas injection holes through the floor of the showerhead. A path splitting manifold is immersed inside the plenum and comprises a gas supply inlet, plural gas outlets, and a plurality of channels comprising plural paths of equal lengths between the inlet and respective ones of the plural outlets.

1 . A gas distribution showerhead assembly for use in a plasma reactor, comprising:
 (a) a showerhead having an internal plenum and comprising a showerhead floor and a plurality of gas injection holes through said floor of said showerhead;   (b) a path splitting manifold immersed inside said plenum and comprising:
 (1) a gas supply inlet; 
 (2) plural gas outlets; 
 (3) a plurality of channels comprising plural paths between said inlet and respective ones of said plural outlets; 
   (c) an electrode underlying said floor of said showerhead, said electrode having plural axial holes in registration with said gas injection holes of said showerhead.   
   
   
       2 . The apparatus of  claim 1  wherein said paths are of equal lengths. 
   
   
       3 . The apparatus of  claim 1  wherein said plurality of channels comprises a hierarchy of channels recursively coupled at their midpoints to outputs other channels of said hierarchy. 
   
   
       4 . The apparatus of  claim 1  wherein said plural gas outlets of said path splitting manifold comprise openings oriented in at least one of (a) an axial direction, (b) a radially outward direction, (c) a radially inward direction. 
   
   
       5 . The apparatus of  claim 1  further comprising a temperature control plate between said showerhead and said electrode. 
   
   
       6 . The apparatus of  claim 1  wherein said plurality of channels are distributed in an azimuthally extending plane. 
   
   
       7 . The apparatus of  claim 5  wherein said plurality of channels comprise:
 a first channel coupled at its midpoint to said inlet;   a pair of second channels each coupled at its midpoint to a respective end of said first channel;   two pairs of third channels, each one of said third channels coupled at its midpoint to a respective end of a corresponding one of said second channels;   said ends of said third channels coupled to respective ones of said plural outlets of said manifold.   
   
   
       8 . The apparatus of  claim 7  wherein said first, second and third channels comprise concentric arcs. 
   
   
       9 . The apparatus of  claim 8  wherein said manifold is circular and said plural outlets of said manifold are equally spaced relative to a circumference of said manifold. 
   
   
       10 . The apparatus of  claim 1  wherein said manifold and said showerhead are contained within respective concentric annular zones. 
   
   
       11 . A gas distribution showerhead assembly for use in a plasma reactor, comprising:
 (I) an inner gas distribution zone comprising:
 (a) an inner annular showerhead; 
 (b) an inner path splitting manifold contained within said inner showerhead; 
 (c) an electrode underlying said inner gas distribution zone; 
   (II) an outer gas distribution zone comprising:
 (a) an outer annular showerhead; and 
 (a) an outer path splitting manifold contained inside said outer annular showerhead; 
 (c) said electrode further underlying said outer gas distribution zone. 
   
   
   
       12 . The apparatus of  claim 11  wherein:
 each one of said manifolds comprises:
 (a) a gas supply inlet; 
 (b) plural gas outlets; 
 (c) a plurality of channels comprising plural paths of equal lengths between said inlet and respective ones of said plural outlets. 
   
   
   
       13 . The apparatus of  claim 12  wherein said plural outlets comprise openings oriented in one of (a) an axial direction, (b) a radially outward direction, (c) a radially inward direction. 
   
   
       14 . The apparatus of  claim 12  wherein:
 each one of said showerheads comprises:
 (a) a showerhead floor; and 
 (b) a plurality of gas injection holes extending axially through said floor of said showerhead; and 
   said electrode underlies the floor of each showerhead, said electrode having plural axial holes in registration with the plural gas injection holes of the showerheads.   
   
   
       15 . The apparatus of  claim 12  wherein said plurality of channels comprise:
 a first channel coupled at its midpoint to said inlet;   a pair of second channels each coupled at its midpoint to a respective end of said first channel;   two pairs of third channels, each one of said third channels coupled at its midpoint to a respective end of a corresponding one of said second channels;   said ends of said third channels coupled to respective ones of said plural outlets of said manifold.   
   
   
       16 . The apparatus of  claim 15  wherein said first, second and third channels comprise concentric arcs. 
   
   
       17 . The apparatus of  claim 12  wherein said plurality of channels comprise a hierarchy of channels recursively coupled at their midpoints to outputs of other channels of said hierarchy. 
   
   
       18 . The apparatus of  claim 16  wherein said manifold is circular and said plural outlets of said manifold are equally spaced relative to a circumference of said manifold. 
   
   
       19 . A plasma reactor, comprising:
 (I) an inner gas distribution zone comprising:
 (a) an inner annular showerhead comprising an interior plenum; 
 (b) an inner path splitting manifold contained inside said interior plenum of said inner annular showerhead; 
 (c) an electrode underlying said inner showerhead; 
   (II) an outer gas distribution zone comprising:
 (a) an outer annular showerhead comprising an interior plenum; 
 (b) an outer path splitting manifold contained inside the interior plenum of said outer annular showerhead; 
 (c) said electrode further underlying said outer showerhead; 
   (III) plural gas sources and respective valves coupled between individual ones of said plural gas sources and respective ones of said inner and outer manifolds;   (IV) an RF source power generator coupled to said electrode.   
   
   
       20 . The apparatus of  claim 19  wherein:
 each one of said manifolds comprises:
 (a) a gas supply inlet; 
 (b) plural gas outlets; 
 (c) a plurality of channels comprising plural paths of equal lengths between said inlet and respective ones of said plural outlets. 
   
   
   
       21 . The apparatus of  claim 20  wherein:
 each one of said showerheads comprises:
 (a) a showerhead floor; and 
 (b) a plurality of gas injection holes extending axially through said floor of said showerhead; and 
   said electrode underlies the floor of each showerhead, said electrode having plural axial holes in registration with the plural gas injection holes of the showerheads.