Diffractometry-based analysis method and associated diffractometer, particularly suitable for samples comprising multiple layers of materials

Patent metadata

Field	Value
Publication number	US-9599580-B2
Application number	US-201314428721-A
Country	US
Kind code	B2
Filing date	Sep 19, 2013
Priority date	Sep 20, 2012
Publication date	Mar 21, 2017
Grant date	Mar 21, 2017

Abstract

A method and device that analyzes a sample with a diffractometer that includes a collimated source, a spectrometric detector, and a detection collimator. The sample is irradiated with an incident beam and the detector has a detection plane with multiple physical or virtual pixels. An measured energy spectrum is established for each pixel and each measured energy spectrum is readjusted. The spectrum is expressed as a function of a variable that accounts for the energy of the scattered radiation and an angle of diffraction. The fulfillment of at least one multiple material criterion is verified. Groups of pixels are formed using the results of the verification step, each group corresponding to a layer of material and different groups corresponding to different layers of material, and the spectra are combined by group, during which, for each group, the readjusted spectra for the pixels of the group are combined.

First claim

The invention claimed is:

1. A method of analyzing a sample of materials by diffractometry, the method comprising:
providing a diffractometer that comprises a source configured to emit an incident beam having a central axis X, and a detector comprising,
a detector material, which, on a near side to the sample of materials, presents a detection plane,
spectrometry measurement means, configured to measure an energy released by each photon interaction with the detector material and to establish at least one measured spectrum;
a detection collimator, associated with the detector, the detector and the detection collimator being arranged so as to have a detection axis D forming a diffraction angle θ with the central axis X of the incident beam;

irradiating the sample with the incident beam,
wherein the detector comprises a pixelated detector comprising means for locating an interaction of a photon with the detector material ( 30 ), so as to define a partition of the detector in physical or virtual pixels (Pi), and associating one of the physical or virtual pixels with each photon interaction;
establishing an energy spectrum for each physical or virtual pixel of the detector;
adjusting each measured energy spectrum (E), by expressing the energy spectrum according to a variable that accounts for an energy of scattered radiation and the diffraction angle θ i , to obtain an adjusted spectra, for each measured energy spectrum;
verifying fulfillment of at least one multimaterial criterion representing the presence of several layers of materials;
forming groups of pixels using results of the verifying step, each group corresponding to a layer of material, where different groups correspond to different layers of material; and
combining spectra by group for each group, where the adjusted spectrum obtained for the pixels (Pi) of the group are combined.

2. A method according to claim 1 , wherein
the adjusted spectra comprises spectra Si(x) in terms of momentum transfer, where a change in variable is carried out using the following formula:

x
=

sin
⁡

(

θ
i

/
2

)

λ

=

E
⁢

⁢

sin
⁡

(

θ
i

/
2

)

hc

,

 where θ i designates the diffraction angle corresponding to the pixel Pi, where the diffraction angle is between the central axis X of the incident beam and an axis Di passing by the center of the pixel Pi and the center of the detection collimator, and λ is a wavelength corresponding to the energy E; and,
wherein combining spectra by group, for each group, comprises summing the adjusted spectra Si(x) of the pixels of the group.

3. A method according to one of the preceding claims, wherein the at least one multimaterial criterion comprises one of:
a variation greater than 10% of a position in the adjusted spectra of a first local maximum, between two adjacent pixels in a transverse direction (T), orthogonal to the detection axis (D);
a variation greater than 10% of a position in the adjusted spectra of a second local maximum, between two adjacent pixels in the transverse direction; or
a variation greater than 10% of a sum of the channels of the adjusted spectrum of each pixel, between two adjacent pixels in the transverse direction.

4. A method according to claim 3 further comprising constructing a curve representing, along a y-axis, the position in the adjusted spectra of the first or second local maximum, based, along an x-axis, on a lateral position (Yi) of the pixel (Pi) or on its diffraction angle θi.

5. A method according to claim 1 , wherein the detector comprises a detector having a pixelated detection plane.

6. A method according to claim 1 , wherein the detector comprises a semiconductor detector material.

7. A method according to claim 1 , wherein the source comprises a polychromatic source, and produces radiation having a maximum energy is about 10 keV to about 200 keV.

8. A method according to claim 1 , wherein the diffraction angle θ is about 2° to about 10°.

9. A method according to claim 1 , wherein the detection collimator comprises an open slot collimator having slot with a height greater than 1 mm.

10. A diffractometer configured to analyze a sample of materials, the diffractometer comprising:
a source configured to emit an incident beam having a central axis X,
a detector comprising,
a detector material, which, on a near side to the sample of materials, presents a detection plane,
spectrometry measurement means, configured to measure an energy released by each photon interaction with the detector material and to establish at least one measured energy spectrum;
a detection collimator, associated with the detector, the detector and the detection collimator being arranged so as to have a detection axis D forming a diffraction angle θ with the central axis X of the incident beam, wherein

the detector is pixelated and comprises means for locating an interaction of a photon with the detector material, so as to define a partition of the detector in physical or virtual pixels, and associating one of the physical or virtual pixels with each photon interaction,
the spectrometry measuring means are configured to establish an energy spectrum Si(E) for each pixel (Pi) of the detector, and
the diffractometer further comprises
adjusting means configured to establish, for each at least one measured energy spectrum, an adjusted spectrum expressed according to a variable that accounts for an energy of scattered radiation and the diffraction angle θ i ,
means for verifying fulfillment of at least one multimaterial criterion representing a presence of several layers of materials,
means for forming groups of pixels, each group corresponding to a layer of material, where different groups correspond to different layers of material, and
means for combining spectra by group, adapted, for each group, to combine the adjusted spectra obtained for the pixels of the group.

11. A diffractometer according to claim 10 , wherein
the adjusting means are configured to establish, for each pixel (Pi), a momentum transfer spectrum S i (x), from the measured spectrum Si(E) by a change in variable using the formula

x
=

sin
⁡

Assignees

• Commissariat Energie Atomique
• Mozido Inc

Inventors

• Ghammraoui Bahaa
• Paulus Caroline
• Tabary Joachim

Classifications

• G01N23/20091 Primary

  Measuring the energy-dispersion spectrum [EDS] of diffracted radiation · CPC title

• G01N2223/639

  material in a container · CPC title