Showerhead with hole size for radical species delivery

Abstract

The showerhead has a first set of holes and a second set of holes. The first set of holes is larger in diameter and length than the second set of holes. The first set of holes extends through a thickness of the showerhead. In some embodiments, the showerhead includes a base portion and a cylindrical portion extending perpendicularly from the base portion. The base portion may define a plenum in fluid communication with the second set of holes but separated from the first set of holes. The second set of holes extends from the plenum to a bottom surface of the showerhead. In some implementations, a first diameter of the first set of holes may be optimized to filter ions from the plasma and pass radicals from the plasma through the showerhead and limit back diffusion of precursors through the showerhead.

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