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Abstract

A microwave plasma generating device including a plasma chamber for generating plasma, a reaction chamber having a specimen stage on which a specimen is treated with the plasma, a gas supply for supplying gas to the plasma generating chamber, a microwave generator for generating a microwave electric field in the plasma and reaction chambers and a plurality of axially spaced apart and concentric electromagnet coils for generating a magnetic field in the plasma and reaction chambers. The microwave electric field and the magnetic field have perpendicularly crossing components and the magnetic field has a strength which decreases in the axial direction from the plasma chamber towards the reaction chamber with constant strength magnetic flux density lines lying in planes which are substantially parallel to each other and perpendicular to the axial direction. The magnetic field produces a flat ECR condition wherein the ECR layer extends perpendicularly to the axial direction over at least 50% of the width of the plasma chamber. In a method of using this device, upper and lower electromagnets produce magnetic fields such that the magnetic field produced by the lower electromagnet is weaker than that produced by the first electromagnet. For instance, the upper electromagnet can be supplied a higher amount of current than the lower electromagnet. Alternatively, the upper and lower electromagnets can be supplied the same amount of current but the lower electromagnet can be larger in diameter than the first electromagnet. This allows the ECR layer to be made thicker in the axial direction than an ECR layer produced by a conventional plasma generating device.

First Claim