Coil for vacuum plasma processor

摘要

200 mm and 300 mm wafers are processed in vacuum plasma processing chambers that are the same or have the same geometry. Substantially planar excitation coils having different geometries for the wafers of different sizes excite ionizable gas in the chamber to a plasma by supplying electromagnetic fields to the plasma through a dielectric window at the top of the chamber. Both coils include plural symmetrical, substantially circular turns coaxial with a center point of the coil and at least one turn that is asymmetrical with respect to the coil center point. Both coils include four turns, with r.f. excitation being applied to the turn that is closest to the coil center point. The turn that is third farthest from the center point is asymmetric in the coil used for 200 mm wafers. The two turns closest to the coil center point are asymmetric in the coil used for 300 mm wafers.