Patent ID: 7371332
Filing Date: 2008-05-13
Classification: H01L

Abstract:
1. A method for etching a layer over a substrate, comprising: placing the substrate in a plasma processing chamber, with a gas distribution system with an inner zone placed opposite an inner portion of the substrate and an outer zone surrounding the inner zone; combining a first component gas with a second component gas; splitting the combined first component gas and second component gas into a first gas and a second gas by passing the combined first component gas and second component gas through a first fixed orifice in a first leg connected to the inner zone and a second fixed orifice in a second leg connected to the outer zone; adding additional first component gas to the second leg, wherein the first component gas has a lower molecular weight than the second gas component, wherein a ratio of the first component gas to the second component gas for the second gas is greater than a ratio of the first component gas to the second component gas for the first gas wherein the second component gas is provided to the first leg connected to the inner zone at a first flow rate greater than or equal to zero from a single tuning gas source, and wherein the adding includes operating a valve connecting the single tuning gas source and the first and second legs such that the first component gas is provided to the second leg connected to the outer zone at a second flow rate greater than or equal to zero from the single tuning gas source, and wherein the second flow rate is different than the first flow rate; providing the first gas to the inner zone of the gas distribution system; providing the second gas to the outer zone of the gas distribution system; simultaneously generating plasmas from the first gas and second gas; and etching the layer, wherein the layer is etched by the plasmas from the first gas and second gas.