US Patent 7371332 Uniform etch system

Etching a layer over a substrate is provided. The substrate is placed in a plasma processing chamber. A first gas is provided to an inner zone within the plasma processing chamber. A second gas is provided to the outer zone within the plasma processing chamber, where the outer zone surrounds the inner zone and the first gas is different than the second gas. Plasmas are simultaneously generated from the first gas and second gas. The layer is etched, where the layer is etched by the plasmas from the first gas and second gas.