For a first period of time, a higher radiofrequency power is applied to generate a plasma in exposure to a substrate, while applying low bias voltage at the substrate level. For a second period of time, a lower radiofrequency power is applied to generate the plasma, while applying high bias voltage at the substrate level. The first and second periods of time are repeated in an alternating and successive manner for an overall period of time necessary to produce a desired effect on the substrate. In some embodiments, the first period of time is shorter than the second period of time such that on a time-averaged basis the plasma has a greater ion density than radical density. In some embodiments, the first period of time is greater than the second period of time such that on a time-averaged basis the plasma has a lower ion density than radical density.