Apparatus and method for imaging a particle beam
AssigneeStaib Instruments GmbH
InventorPhilippe Staib
Life of this patent
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Abstract
An apparatus and method for imaging on a detector a particle beam of charged particles having a distinct energy distribution and a distinct angle distribution. The apparatus has deflectors which are provided to create in the particle beam essentially parallel particle paths spaced to correspond to their original angle distribution. The deflectors also direct the particle beam to semi-transmissive, aligned filter electrodes, which produce a potential difference to create a deceleration field to allow the particles to pass through by means of energy selectivity.
Claims20
An apparatus for imaging on a detector a particle beam comprising charged particles from a sample having a distinct energy distribution, a distinct angle distribution and a direction of propagation comprising semi-transmissive filter electrodes arranged to generate a potential difference to create a deceleration field and to allow particles of said particle beam to pass through by means of energy selectivity;
- and at least one stop lens deflector positioned between said sample and said semi-transmissive filter electrodes to create in the particle beam essentially parallel particle paths which are spaced in proportion to the angle distribution of the particles and which are directed to the filter electrodes, wherein said at least one stop lens is positioned closer to said semi-transmissive filter electrodes than is said sample and comprises at least two field forming electrodes being arranged to be powered with increasing stopping potentials.
A process for imaging on a detector means a particle beam comprising charged particles having a distinct energy distribution and a distinct angle distribution, wherein the particle beam passes through semi-transmissive filter electrodes which are capable of generating a potential difference to create a deceleration field in order to allow particles to pass through by means of energy selectivity, the steps which comprise:
- directing said charged particles onto essentially parallel particle paths to the filter electrodes such that the spacing between the parallel paths is proportional to the angle distribution by passing said charged particles in substantially one direction through at least one stop lens deflector, wherein said at least one stop lens deflector comprises two field forming electrodes which are powered with increasing stopping potentials.
An imaging device for imaging a particle beam of charged particles, wherein said particle beam is imaged in a direction substantially along a longitudinal axis, said imaging device comprising:
- (a) a stop lens through which said particle beam can propagate in one downstream direction, said stop lens comprising at least two electrodes at spaced separation and each comprising first and second ends extending substantially along said longitudinal axis, said electrodes being aligned in order of increasing potential as an absolute value according to said downstream direction, said particle beam propagating in said downstream direction by initially passing said first ends of said at least two electrodes within said spaced separation and finally passing said second ends of said at least two electrodes, wherein said stop lens decelerates said charged particles and directs said charged particles onto essentially parallel paths as said particle beam propagates through said stop lens in said downstream direction;
- (b) a filter electrode aligned with said stop lens and positioned downstream of said stop lens, said filter electrode receiving said particle beam directly from said stop lens after said particle beam passes said second ends of said at least two electrodes, said filter electrode producing a potential capable of extracting a portion of said charged particles from said particle beam below an energy threshold while decelerating said charged particles not below said energy threshold;
- and
- (c) a charged particle detector aligned with said filter electrodes and positioned downstream of said filter electrodes.
A method of imaging a particle beam of charged particles propagating along a longitudinal axis and at angles to said axis, respectively, comprising:
- (a) deflecting a number of said charged particles with at least one stop lens deflector such that said number of said charged particles propagate along paths essentially parallel to said axis, said paths being spaced proportionally to said angles, wherein said at least one stop lens deflector comprises at least two field forming electrodes which are powered with increasing stopping potentials, said at least two field forming electrodes being at spaced separation and each comprising first and second ends extending substantially along said longitudinal axis, said particle beam propagating one time through each of said at least one stop lens deflector by propagating past said first ends, between said at least two field forming electrodes in said spaced separation, and directly out from said second ends;
- (b) screening said charged particles through a deceleration potential to extract a portion of said charged particles below an energy threshold;
- and
- (c) imaging said charged particles not extracted in said screening step.
Dependencies are inferred from the claim text.