| CPC H01L 21/3065 (2013.01) [H01J 37/32642 (2013.01); H01J 37/32669 (2013.01)] | 20 Claims |
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1. A method of processing a substrate, the method comprising:
loading the substrate in a plasma processing chamber, the substrate comprising a patterned hard mask layer and an underlying layer, the plasma processing chamber comprising a RF power source and a set of electromagnets;
flowing a process gas into the plasma processing chamber;
providing power to the set of electromagnets to generate an azimuthally symmetric magnetic field in the plasma processing chamber, the azimuthally symmetric magnetic field comprising a ring X point where the azimuthally symmetric magnetic field is locally neutralized, the ring X point being located concentrically with the substrate;
generating a plasma from the process gas in the plasma processing chamber by powering the RF power source;
while providing the power to the set of electromagnets, exposing the substrate to the plasma and etching the underlying layer selectively to the patterned hard mask layer; and
while exposing the substrate to the plasma, changing the power to the set of electromagnets to change the azimuthally symmetric magnetic field.
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