Recursive pumping for symmetrical gas exhaust to control critical dimension uniformity in plasma reactors

Abstract

Embodiments of the present invention provide apparatus and methods for reducing non-uniformity and/or skews during substrate processing. One embodiment of the present invention provides a flow equalizer assembly for disposing between a vacuum port and a processing volume in a processing chamber. The flow equalizing assembly includes a first plate having at least one first opening, and a second plate having two or more second openings. The first and second plates define a flow redistributing volume therebetween, and the at least one first opening and the two or more second openings are staggered.

1 . A method for pumping a processing chamber, comprising:
 directing fluid flow from a processing volume to a vacuum port through a flow equalizer assembly, wherein the flow equalizer assembly comprises a first plate having at least one first opening, and a second plate having two or more second openings, the at least one first opening and the two or more second openings are staggered, and directing the fluid flow comprises:
 flowing one or more gases from the processing volume through the two or more second openings to a flow redistributing volume defined between the first and second plates; and 
 flowing the one or more gases from the flow redistributing volume through the at least one first opening to the vacuum port. 
   
     
     
         2 . The method of  claim 1 , wherein flowing one or more gases to the flow redistributing volume comprises flowing the one or more gases through each of the two or more second openings to a corresponding sub-redistributing volume divided by two or more dividers positioned between the first and second plates, and each of the sub-redistributing volume is in connection with one of the at least one first opening. 
     
     
         3 . The method of  claim 2 , further comprising adjusting locations of the two or more dividers to adjust flow distribution in the flow redistributing volume. 
     
     
         4 . The method of  claim 2 , further comprising adding an additional first divider between the first and second plates to create a sub-redistributing volume that is not in fluid connection with any first openings or second openings. 
     
     
         5 . The method of  claim 1 , further comprising tuning the flow equalizer assembly to obtain symmetric fluid flow in the processing volume. 
     
     
         6 . The method of  claim 1 , further comprising tuning the flow equalizer assembly to compensate structural non-symmetries in the processing chamber.