Method and apparatus for improving processing and reducing charge damage

Abstract

The present invention provides an apparatus and method for processing a workpiece in an inductively coupled plasma reactor. Inductive power is applied to the reactor to generate a plasma. A magnetic field is generated within the plasma reactor having lines of force oriented perpendicular to the workpiece surface. It is a feature of the invention to control the electron temperature near the surface of the workpiece by controlling the applied magnetic field. It is a further feature to increase average ion density near the workpiece without otherwise causing damage to the workpiece due to uneven charge build-up. The applied magnetic field can be time invariant or time variant. In both cases, processing can be optimized by adjusting the magnitude of the magnetic field to a level just below where damage due to uneven charge build-up occurs. With the time variant field, the average ion density can be adjusted with respect to average electron temperature. As such, average ion density near the workpiece can by increased without otherwise causing damage to the workpiece. It is a further feature of the present invention to provide independently controllable conductors for generating the magnetic field and to provide an adjustable non-uniformly distributed magnetic field within the chamber. This can be used to selectively control plasma density or to selectively confine process gas species.