Microcalorimetry for X-ray spectroscopy
AssigneeFEI Company
InventorsMilos Toth, Michael R. Scheinfein, Eric Silver, David Narum
Life of this patent
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Abstract
An improved microcalorimeter-type energy dispersive x-ray spectrometer provides sufficient energy resolution and throughput for practical high spatial resolution x-ray mapping of a sample at low electron beam energies. When used with a dual beam system that provides the capability to etch a layer from the sample, the system can be used for three-dimensional x-ray mapping. A preferred system uses an x-ray optic having a wide-angle opening to increase the fraction of x-rays leaving the sample that impinge on the detector and multiple detectors to avoid pulse pile up.
Claims21
A system for x-ray mapping, comprising:
- an ion beam focusing column;
- an electron focusing column for focusing an electron beam into a sufficiently small spot to resolve material separated by 15 nm;
- an x-ray optic for receiving x-rays emitted from the sample, the x-ray optic receiving and transmitting x-rays impinging on the optic entrance at angles up to at least 10 degrees;
- and
- multiple x-ray detectors, each x-ray detector including:
- an absorber for absorbing x-rays exiting the x-ray optic;
- and
- a temperature sensing device for converting a change in temperature of the x-ray absorber into an electronic signal, the multiple x-ray detectors capable of resolving energy difference of 15 eV,
- the system capable of determining a material map composed of 100 pixels by 100 pixels while collecting x-rays for a period of less than twenty minutes.
A method of forming a high spatial resolution, high energy resolution x-ray map of a sample, comprising:
- a. directing a beam of electrons having energies of less than 5,000 eV toward a sample in a vacuum chamber, the electron beam forming a spot having a diameter of less than 50 nm on the sample;
- b. conducting x-rays created by the impact of the electrons on the sample through an x-ray optic towards multiple cryogenic x-ray detectors;
- c. determining the energy of the x-rays impacting the detector to determine the material present at the location at which the electron beam impacts the sample;
- d. moving the impact point of the electron beam to a different point on the surface and repeating steps b and c for an array of at least 5,000 points in a time period of less than one hour to produce a map of material present in the region scanned by the electron beam.
A system for x-ray mapping of a sample to show the material present at different positions on the sample, comprising:
- an electron focusing column capable of focusing an electron beam to a sufficiently small beam spot to resolve material separated by 15 nm;
- an x-ray optic for receiving x-rays emitted from the sample, the entrance to the x-ray optic receiving x-rays over a solid angle of at least 10 degrees;
- and
- multiple x-ray detectors, each x-ray detector including:
- an absorber for absorbing x-rays exiting the x-ray optic;
- and
- a temperature sensing device for converting a change in temperature of the x-ray absorber into an electronic signal, the multiple x-ray detectors are capable of resolving energy difference of 15 eV,
- the system capable of determining a material map composed of 100 by 100 pixels while collecting x-rays for a period of less than twenty minutes.
Dependencies are inferred from the claim text.