Patent ID: 8028655
Filing Date: 2011-10-04
Classification: H01J

Abstract:
1. A low-inductance RF antenna for use in producing a high-density, ring-shaped plasma with enhanced ionization, for the plasma processing of a semiconductor wafer having a diameter of 300 millimeters or larger, by inductively-coupling energy into alternating high and low density regions in a peripheral ring in a vacuum chamber, the antenna comprising: a central axis: a single tubular conductor having constant cross-section wound in a plurality of peripheral conductor windings wound in the same direction around the central axis such that current flowing in the peripheral conductor windings flows around the central axis in the same direction; the plurality of peripheral windings being arranged in a cylindrical segmented configuration that produces an alternating plurality of high and low-efficiency antenna segments, the windings within each segment having a modulated shape of alternating wide and narrow spacings between adjacent pairs of the windings around the central axis; the high-efficiency segments each including closely-spaced parallel conductor lengths of at least two peripheral conductor windings of the plurality of peripheral conductor windings; the low-efficiency segments each including relatively widely-spaced parallel conductor lengths of the at least two peripheral conductor windings of the plurality of the peripheral conductor winding; the high-efficiency segments of the antenna thereby having a concentrated current-carrying configuration that provides relatively closely-spaced parallel paths for said current that produce relatively high-strength magnetic fields externally adjacent and surrounding the at least two closely spaced peripheral conductor windings, and the low-efficiency segments thereby having a distributed current-carrying configuration that provides relatively widely-spaced parallel paths for said current that produce relatively low-strength magnetic fields externally adjacent and surrounding the widely spaced peripheral conductor windings; whereby RF current in the conductor causes RF energy to inductively couple from the segments of the antenna to the plasma in a peripheral ring of alternating high and low density regions spaced from the central axis of the antenna.