Patent ID: 7837826

Claim:
A device for confining plasma formed in a plasma processing apparatus that includes an upper electrode opposite a lower electrode, said lower electrode being adapted to support a substrate thereover and wherein plasma is generated between said substrate and said upper electrode during operation, said device comprising: a dielectric support ring adapted to concentrically surround said upper electrode; and a plurality of coil units spaced apart in a circumferential direction and mounted on said dielectric support ring, each of said coil units including a semicircular or U-shaped ferromagnetic core positioned on and parallel to a radial line originating from a center of said dielectric support ring and a first coil wound around said ferromagnetic core and coupled to a first radio frequency (RF) power source, said ferromagnetic core of each of said coil units having two ends on said radial line originating from the center of the dielectric support ring and the ends facing the dielectric support ring, wherein said coil units, upon receiving RF power from said first RF power source, generate electric and magnetic fields that confine said plasma.