Patent ID: 7749353

Claim:
An apparatus for etching a feature in an etch layer through a mask over a substrate, comprising: a plasma processing chamber, comprising: a chamber wall forming a plasma processing chamber enclosure; a substrate support for supporting a substrate within the plasma processing chamber enclosure; a pressure regulator for regulating the pressure in the plasma processing chamber enclosure; at least one electrode for providing power to the plasma processing chamber enclosure for sustaining a plasma; a gas inlet for providing gas into the plasma processing chamber enclosure; and a gas outlet for exhausting gas from the plasma processing chamber enclosure; a gas source in fluid connection with the gas inlet; a first power source for providing power within the chamber wall at a first frequency; a second power source for providing power within the chamber wall at a second frequency different than the first frequency; a third power source for providing power within the chamber wall at a third frequency different than the first frequency and the second frequency; and a controller controllably connected to the gas inlet, the first power source, the second power source, and the third power source, comprising: at least one processor; and computer readable media, comprising: computer readable code for introducing an etchant gas through the gas inlet; computer readable code for performing a first etch step, comprising: providing energy from the first power source at a first power level; providing energy from the second power source at a second power level; providing energy from the third power source at a third power level, wherein in the first power level and the third power level are greater than zero, wherein the first etch is used to etch a feature in the layer to be etched to a first depth; and computer readable code for performing a second etch step, comprising: providing energy from the first power source at a fourth power level; providing energy from the second power source at a fifth power level; providing energy from the third power source at a sixth power level, wherein at least one of the fourth and sixth power levels is greater than zero and the fifth power level is greater than zero, and wherein a condition is selected from the group of the first power level not being equal to the fourth power level and the third power level not being equal to the sixth power level, wherein the second etch etches the feature in the layer to be etched to a second depth greater than the first depth.