A plasma etch reactor 20 includes a upper electrode 24, a lower electrode 24, a peripheral ring electrode 26 disposed therebetween. The upper electrode 24 is grounded, the peripheral electrode 26 is powered by a high frequency AC power supply, while the lower electrode 28 is powered by a low frequency AC power supply, as well as a DC power supply. The reactor chamber 22 is configured with a solid source 50 of gaseous species and a protruding baffle 40. A nozzle 36 provides a jet stream of process gases in order to ensure uniformity of the process gases at the surface of a semiconductor wafer 48. The configuration of the plasma etch reactor 20 enhances the range of densities for the plasma in the reactor 20, which range can be selected by adjusting more of the power supplies 30, 32.