Ion detector for ion beam applications
AssigneeInternational Business Machines Corporation
InventorsSteven B. Herschbein, Narender Rana, Chad Rue, Michael R. Sievers
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Abstract
Detection of weak ion currents scattered from a sample by an ion beam is improved by the use of a multiplier system in which a conversion electrode converts incident ions to a number of secondary electrons multiplied by a multiplication factor, the secondary electrons being attracted to an electron detector by an appropriate bias. In one version, the detector is a two stage system, in which the secondary electrons strike a scintillator that emits photons that are detected in a photon detector such as a photomultiplier or a CCD.
Claims20
An ion beam system comprising:
- a beam generator for generating and directing a primary ion beam at a sample;
- at least one detector for detecting secondary particles scattered from said sample by said primary ion beam;
- a conversion electrode disposed azimuthally about said detector so as to receive ions scattered from said sample, said conversion electrode being adapted to emit more than one secondary electron for each ion striking it, the number of secondary electrons being related to the number of incident ions by a multiplication factor;
- in which
- said conversion electrode is biased negative with respect to a bias of said sample and said detector is biased positive with respect to said conversion electrode, whereby a first number of ions scattered from said sample and received by said conversion electrode emits said first number multiplied by said multiplication factor of secondary electrons that are attracted to said detector.
An ion beam system comprising:
- a beam generator for generating and directing a primary ion beam at a sample;
- at least one detector for detecting secondary particles scattered from said sample by said primary ion beam;
- a conversion electrode disposed to receive ions scattered from said sample, said conversion electrode being adapted to emit more than one secondary electron for each ion striking it, the number of secondary electrons being related to the number of incident ions by a multiplication factor;
- in which
- said conversion electrode is biased negative with respect to a bias of said sample and said detector is biased positive with respect to said conversion electrode, whereby a first number of ions scattered from said sample and received by said conversion electrode emits said first number multiplied by said multiplication factor of secondary electrons that are attracted to said detector;
- and
- a source of ionizing photons that are directed through a plume of secondary particles scattered from said sample, whereby at least some neutral particles in said plume of secondary particles are ionized.
A system for detecting a beam of ions comprising:
- at least one detector for detecting electrons;
- a conversion electrode disposed azimuthally about said detector so as to receive said beam of ions, said conversion electrode being adapted to emit more than one secondary electron for each ion striking it, the number of secondary electrons being related to the number of incident ions by a multiplication factor;
- in which said conversion electrode is biased to attract said beam of ions and said detector is biased positive with respect to said conversion electrode, whereby a first number of ions received by said conversion electrode emits said first number multiplied by said multiplication factor of secondary electrons that are attracted to said detector.
Dependencies are inferred from the claim text.