A substrate is disposed on a substrate holder within a process module. The substrate includes a mask material overlying a target material with at least one portion of the target material exposed through an opening in the mask material. A bi-modal process gas composition is supplied to a plasma generation region overlying the substrate. For a first period of time, a first radiofrequency power is applied to the bi-modal process gas composition to generate a plasma to cause etching-dominant effects on the substrate. For a second period of time, after completion of the first period of time, a second radiofrequency power is applied to the bi-modal process gas composition to generate the plasma to cause deposition-dominant effects on the substrate. The first and second radiofrequency powers are applied in an alternating and successive manner for an overall period of time to remove a required amount of exposed target material.
