Method and apparatus for enhancing yield of secondary ions
AssigneeFEI Company
InventorsRobert L. Gerlach, Locke Christman, Mark Utlaut
Life of this patent
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Abstract
The sensitivity of a secondary ion mass spectrometer (SIMS) is increased by using water vapor to enhance the yield of positive secondary ions sputtered by a primary focused ion beam. Water vapor is injected through a needle that is positioned close to the sample and electrically biased to reduce interference with secondary ion collection field. The sensitivity is enhanced for metals in particular, which tend to be sputtered as positive ions.
Claims21
A method of secondary ion mass spectrometry comprising:
- positioning a sample to be analyzed within an enclosed chamber,
- supplying water vapor within said chamber,
- generating an ion beam,
- directing said ion beam toward said surface for sputtering secondary ions from at least a portion of said surface,
- receiving secondary ions from said surface of said sample, and
- directing said secondary ions to a mass analyzer.
A method of analyzing a sample comprising:
- positioning said sample on a stage within a substantially gas tight chamber of a focused ion beam system,
- directing water vapor or hydrogen peroxide towards a region of said sample where analysis is desired, for enabling reaction between the water vapor and the material from which said sample is formed,
- generating a focused ion beam and directing said ion beam toward said region of said sample for generating secondary ions, and
- analyzing said secondary ions to determine the elemental makeup of said region of said sample with a mass analyzer.
A method of increasing the secondary ion yield of sample materials bombarded by an ion beam, said method comprising the steps of:
- directing an ion beam toward a location on a sample material, and
- directing water vapor or hydrogen peroxide at said location while said ion beam is incident thereon for enhancing secondary ion yield for elemental analysis with a mass analyzer.
Apparatus for performing secondary ion mass spectrometry with respect to a sample, said apparatus comprising:
- an ion source for directing an ion beam toward a sample,
- a water vapor source for directing water vapor or hydrogen peroxide toward the sample at the impact area of the ion beam,
- a mass analyzer for analyzing secondary ions from the sample;
- and
- the apparatus configured to direct the ion beam toward the sample to which water vapored is adhered while collecting secondary positive ions for analysis in the mass analyzer.
Dependencies are inferred from the claim text.