Patent ID: 6136166
Filing Date: 2000-10-24
Classification: C23C,H01J

Abstract:
An apparatus for providing a uniform magnetic field across the surface of a wafer having edge regions and a central region comprising:a rectangular configuration including spaced flux guides formed of high permeability material disposed adjacent to said wafer, said flux guides being opposite to each other, said flux guides having tapered portions in contact with said edge regions of the wafer and extending to and narrowing towards said central region of the wafer, and outer rectangular sections adjacent to said tapered portions and spaced from the wafer by said tapered portions, said outer rectangular sections formed with longitudinal segments and said tapered portions formed with longitudinal segments that are parallel to and contiguous with said longitudinal segments of said outer rectangular sections, said longitudinal segments of said tapered portions having widths substantially narrower than the widths of said outer rectangular sections; andmagnetic means located closely adjacent to said wafer;whereby the magnetic field strength at the edge regions of the wafer is effectively reduced and the field at the central region of the wafer is shaped so that field intensity across the entire surface of the wafer is uniform.