Diverter magnet arrangement for plasma processing system

Claim 1

A magnetically enhanced plasma processing apparatus, the apparatus including a vacuum chamber, a workpiece support electrode disposed within the chamber, the electrode having a length dimension between first and second ends thereof, a width dimension between first and second side edges of said electrode, a thickness dimension smaller than the length and width dimensions, and a processing surface for supporting a flat workpiece between the first and second ends and first and second side edges; primary magnet means, including first and second magnetic members disposed at the first and second ends of the electrode, respectively, the first magnetic member constituting a first magnetic pole of one polarity and the second magnetic member constituting a second magnetic pole of opposite polarity, the first and second magnetic poles generating a primary magnetic field that extends between the poles in the direction of the length dimension of the electrode in front of the processing surface and extends continuously around the electrode; auxiliary magnet means spaced from the processing surface and having third and fourth magnetic poles disposed above, parallel to, and opposite the first and second magnetic poles, respectively, of the primary magnet means, said auxiliary magnet means being disposed for generating an auxiliary magnetic field that tends to flatten the primary magnetic field in front of the processing surface; means for evacuating the vacuum chamber; means for delivering at least one preselected gas to the chamber; and means for delivering electrical energy to the electrode sufficient to generate a plasma of ionized particles of said gas within the magnetic field in front of the processing surface, the polarity of the magnetic members being predetermined such that electron drift within said plasma occurs generally in the direction from the first edge of the electrode toward the second edge thereof, wherein the improvement comprises: diverter magnet means for generating a third magnetic field having curved lines of force centered on an axis spaced from the first edge of the electrode such that the third magnetic field interacts with the result of the primary field and the auxiliary field at the first edge of the electrode and acts to stabilize the plasma in this region.