Precise control of etch topography and pattern transfer

Abstract

Exemplary semiconductor processing methods may include providing one or more etchant precursors to a processing region of a semiconductor processing chamber. A substrate may be housed within the processing region. Alternating pairs of a silicon-and-oxygen-containing material and a silicon-and-nitrogen-containing material may be disposed on the substrate. A feature may extend at least partially through the alternating layers. The methods may include forming plasma effluents. The methods may include contacting the substrate with the plasma effluents. The contacting may etch the silicon-and-oxygen-containing material and / or the silicon-and-nitrogen-containing material. The methods may include applying a bias power while contacting the substrate with the plasma effluents. The bias power may be applied at a first duty cycle to selectively etch the silicon-and-oxygen-containing material. The bias power may be applied at a second duty cycle less than the first duty cycle to selectively etch the silicon-and-nitrogen-containing material.

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