Offset magnet compensation for non-uniform plasma

摘要

A non-axisymmetric electromagnet coil used in plasma processing in which at least one electromagnet coil is not symmetric with the central axis of the plasma processing chamber with which it is used but is symmetric with an axis offset from the central axis. When placed radially outside of an RF coil, it may reduce the azimuthal asymmetry in the plasma produced by the RF coil. Axisymmetric magnet arrays may include additional axisymmetric electromagnet coils. One axisymmetric coil is advantageously placed radially inside of the non-axisymmetric coil to carry opposed currents. The multiple electromagnet coils may be embedded in a molded encapsulant having a central bore about a central axis providing the axisymmetry of the coils.

主权项

1. A plasma processing chamber, comprising:
a vacuum chamber arranged about a central axis; a pedestal for supporting a substrate in a first plane perpendicular to the central axis adjacent a processing space in the vacuum chamber; a non-axisymmetric electromagnet coil symmetrically wound about an offset axis offset from the central axis by a predetermined and fixed offset and extending about the offset axis along a second plane around the processing space; a DC power supply providing continuous DC power to the non-axisymmetric electromagnet coil; and a single-turn RF inductive coil wound about the central axis and having a pair of junctions for connection to an RF power supply and to ground, wherein the predetermined and fixed offset is aligned along a direction from the pair of junctions to the central axis.