Wien filter apparatus with hyperbolic surfaces
AssigneeHitachi, Ltd.
InventorsTeruo Kohhashi, Hideo Matsuyama
Life of this patent
Estimating the term…
Abstract
A Wien filter is used with secondary electrons that are emitted from a primary electron beam scanning a sample surface in a scanning electron microscope (SEM) used as an energy analyzer or a spin rotater with charged particle beams. The beam is focussed into an interior area of the filter that has magnetic and electric fields generated to cross one another. The beam intersects the crossed fields perpendicularly. The faces of either the magnetic pole pieces or the electrodes have a shape approximating the shape of a portion of a hyperbola, while the other of the faces are substantially planar. Auxiliary electrodes extend parallel to the beam's path of travel between the electrodes. The filter provides a wide area that enables stigmatic focussing of a wide diameter beam.
Claims23
A Wien filter apparatus, comprising:
- a Wien filter receiving an electron beam that passes through the filter along a longitudinal axis of the filter, including:
- means generating an electric field including electrodes having respective faces, and means generating a magnetic field crossing said electric field in said area perpendicular to said longitudinal axis, wherein said magnetic field generating means includes opposed pole pieces having respective pole faces, and wherein said faces of one of (i) said electrodes and (ii) said pole pieces have a shape approximating a curve of a portion of a hyperbola.
A Wien filter apparatus for use in a scanning electron microscope, wherein a primary electron beam scans a sample of a surface and secondary electrons are emitted and formed into a beam, comprising:
- focusing means for receiving said electron beam formed of said secondary electrons;
- and
- a Wien filter for receiving said electron beam focused by said focusing means, said beam passing through the filter and extending along a longitudinal axis of the filter;
- said Wien filter including:
- means generating an electric field including electrodes having respective faces, and means generating a magnetic field crossing said electric field in said internal area perpendicular to said longitudinal axis, wherein said magnetic field generating means includes opposed pole pieces having respective pole faces, wherein said faces of one of (i) said electrodes and (ii) said pole pieces have a shape approximating a curve of a portion of a hyperbola.
A Wien filter apparatus, comprising:
- a Wien filter receiving an electron beam that passes through the filter between oppositely facing electrodes extending opposite one another in a first direction and oppositely facing magnetic pole pieces extending in a second direction orthogonal to said first direction, wherein the electron beam travels along a longitudinal axis of the filter perpendicular to said first and second directions;
- said electrodes generating an electric field and said pole pieces generating a magnetic field crossing said electric field;
- and said electrodes having respective electrode faces, each having a shape approximating a curve of a portion of a hyperbola, wherein one of said curved faces is concave and the other of said curved faces is convex.
A Wien filter apparatus, comprising:
- a Wien filter receiving an electron beam that passes through an internal area of the filter between oppositely facing electrodes extending opposite one another in a first direction and oppositely facing magnetic pole pieces extending in a second direction orthogonal to said first direction, wherein the electron beam travels along a longitudinal axis of the filter perpendicular to said first and second directions;
- said electrodes generating an electric field and said pole pieces generating a magnetic field crossing said electric field in said internal area;
- and said opposed pole pieces having respective pole faces, each having a shape approximating a curve of a portion of a hyperbola.
Dependencies are inferred from the claim text.