Patent ID: 7400096
Filing Date: 2008-07-15
Classification: H01J,H05H

Abstract:
1. A plasma source comprising: a plasma chamber having a central axis, an entrance hole having the same central axis at one axial end of the chamber and an exit plane having the same central axis at an opposed axial end; a chamber wall composed of a ferromagnetic material that extends from the entrance hole to the exit plane to surround the plasma chamber; an approximately annular entrance magnet ring surrounding the entrance hole, and attached inside the chamber wall such that a first magnetic pole is against the chamber wall and a second opposed magnetic pole is an inner pole facing into the plasma chamber; and an entrance pole piece composed of a ferromagnetic material, having a first face that is attached to and extends substantially axially into the plasma chamber from the entrance hole to a continuing second face that extends perpendicularly away from the central axis across at least a portion of the inner pole of the entrance magnet ring, and the second face extends farther away from the central axis than the entrance magnet ring; a microwave waveguide having an inside dimension approximately equal to an inside dimension of the entrance hole, and having the same central axis as the plasma chamber, wherein the waveguide has an open end attached to the entrance hole and is aligned for directing microwaves through the entrance hole along the central axis into the plasma chamber; a first section of the wall that extends out away from the central axis from the entrance hole to a peripheral junction; a second section of the wall that extends mostly axially from the junction to the exit plane; an approximately annular first intermediate magnet ring attached inside the wall near the junction such that a one of its first and second magnetic poles is against the wall and the one magnetic pole's opposed magnetic pole is facing into the plasma chamber; an annular exit flange composed of a ferromagnetic material, that is attached to and extends into the plasma chamber toward the central axis along the exit plane from the wall to an inner edge; an approximately annular exit magnet ring surrounding the inner edge of the exit flange, and attached inside the exit flange such that a one of its first and second magnetic poles is against the exit flange and the one magnetic pole's opposed magnetic pole is facing into the plasma chamber; and a magnetic circuit configuration wherein all magnet rings are composed of permanent magnet material such that inward facing magnetic poles alternate polarity versus adjacent magnet rings while proceeding along the wall sequentially from the entrance magnet ring to the exit magnet ring.