A plasma processing chamber and methods for operating the chamber are provided. An exemplary chamber includes an electrostatic chuck for receiving a substrate and a dielectric window connected to a top portion of the chamber. An inner side of dielectric window faces a plasma processing region that is above the electrostatic chuck and an outer side of the dielectric window is exterior to the plasma processing region. Inner and outer coils are disposed above the outer side of the dielectric window, and the inner and outer coils are connected to a first RF power source. A powered grid is disposed between the outer side of dielectric window and the inner and outer coils. The powered grid is connected to a second RF power source that is independent from the first RF power source.