Patent ID: 6028395
Filing Date: 2000-02-22
Classification: H01J

Abstract:
A vacuum plasma processor for treating a workpiece with a plasma comprising a vacuum chamber where the workpiece is adapted to be located, the chamber having an inlet for introducing into the chamber a gas which can be converted into the plasma for treating the workpiece, a coil positioned to couple an RF field to the gas for exciting the gas to the plasma state, the RF field derived from a main part of the coil interacting with an electromagnetic shield, the electromagnetic shield substantially confining the coil RF field to structure associated with the processor and interacting with the RF field derived from the main coil part in such a manner as to tend to reduce (a) the RF field derived from the main coil part in a part of the plasma generally aligned with a peripheral portion of the main coil part and (b) plasma flux density in the part of the plasma generally aligned with the main coil part peripheral portion relative to flux density of a portion of the plasma generally inside the part of the plasma generally aligned with the main coil part peripheral portion, the main coil part peripheral portion including an additional coil structure for supplying an additional amount of RF field to the portion of the plasma generally aligned with the main coil part peripheral portion, the additional amount of RF field supplied increasing the plasma flux density in the part of the plasma generally aligned with the main coil part peripheral portion.