Material characterization using ion channeling imaging

Patent metadata

Field	Value
Publication number	US-2018136147-A1
Application number	US-201615354972-A
Country	US
Kind code	A1
Filing date	Nov 17, 2016
Priority date	Nov 17, 2016
Publication date	May 17, 2018
Grant date	—

Abstract

A system and method of characterizing a work piece, comprising:
scanning an ion beam across an exposed surface of a work piece, the ion beam causing the emission of secondary electrons at multiple imaging points of the scan, the number of secondary electrons emitted varying at different ones of the multiple imaging points; detecting the emitted secondary electrons at each of the multiple imaging point to form an image, the brightness of each point in the image being determined by the number of secondary electrons detected at a corresponding imaging point on the work piece; determining grain boundaries in the work piece using the differences in brightness at different points in the image, the grain boundaries defining multiple grains; directing a charged particle beam toward one or more analysis points within one or more of the grains, the number of the one or more analysis points within each grain being less than the number of imaging points within the same grain; and detecting emissions from the work piece sample at each analysis point; and determining the composition or crystal structure of one or more grains based on the detected secondary emissions.

First claim

We claim as follows:

1 . A method of characterizing a work piece, comprising:
a. scanning an ion beam across an exposed surface of a work piece, the ion beam causing the emission of secondary electrons at multiple imaging points of the scan, the number of secondary electrons emitted varying at different ones of the multiple imaging points; b. detecting the emitted secondary electrons at each of the multiple imaging point to form an image, the brightness of each point in the image being determined by the number of secondary electrons detected at a corresponding imaging point on the work piece; c. determining grain boundaries in the work piece using the differences in brightness at different points in the image, the grain boundaries defining multiple grains; d. directing a charged particle beam toward one or more analysis points within one or more of the grains, the number of the one or more analysis points within each grain being less than the number of imaging points within the same grain; e. detecting emissions from the work piece sample at each analysis point; and f. determining the composition or crystal structure of one or more grains based on the detected secondary emissions.

2 . The method of claim 1 further comprising repeatedly removing a layer of material from the work piece surface by laser processing to expose new surfaces on the work piece and repeating the steps a-f on each of the exposed new surfaces.

3 . The method of claim 2 further comprising reconstructing a three-dimensional image of the work piece using the determine grain boundaries and composition or crystal structure determined from the different exposed surfaces of the work piece.

4 . The method of claim 1 in which:
directing a charged particle beam toward one or more analysis points comprises directing an electron beam toward one or more analysis points; and
detecting emissions from the work piece at each analysis point comprises forming an electron backscatter diffraction image.

5 . The method of claim 1 in which:
directing a charged particle beam toward one or more analysis points comprises directing an electron beam toward one or more analysis points;
detecting emissions from the work piece at each analysis point comprises detecting x-rays; and
determining the composition of one or more grains comprises determining the energy of the x-rays.

6 . The method of claim 5 in which determining the energy of the x-rays comprises using energy dispersive x-ray analysis.

7 . The method of claim 5 in which
determining the energy of the x-rays comprises forming an x-ray spectrum; and
determining the composition or crystal structure of one or more grains further comprises comparing the x-ray spectrum to reference x-ray spectra of known materials.

8 . The method of claim 5 in which determining the composition or crystal structure of one or more grains further comprises comparing the relative number of x-rays in specific frequency channels with the relative number of x-rays in those frequency channels for known materials.

9 . The method of claim 1 in which:
directing a charged particle beam toward one or more analysis points comprises directing an ion beam toward one or more analysis points;
detecting emissions from the work piece at each analysis point comprises detecting emissions from the work piece at a first orientation and detecting emissions from the work piece at a second orientation; and
determining the composition or crystal structure of one or more grains based on the detected secondary emissions comprises determining the crystal structure by comparing the emissions from the same grain at the different orientations.

10 . The method of claim 6 in which:
directing an ion beam toward one or more analysis points comprises directing an ion beam toward the one or more analysis points at a non-normal angle to the work piece surface; and
detecting emissions from the work piece at a second orientation comprises rotating the work piece about an axis normal to the work piece surface before detecting the emissions.

11 . The method of claim 1 in which the grains are composed of crystals characterized by crystal planes:
directing a charged particle beam toward one or more analysis points comprises directing an ion beam toward one or more analysis points;
detecting emissions from the work piece at each analysis point comprises detecting emissions from each analysis point with the ion beam oriented at different angles to the crystal planes to define a relationship between the emissions and the orientation angle; and
determining the composition or crystal structure of one or more grains based on the detected secondary emissions comprises determining the crystal structure from the relationship between the emissions and the orientation angle.

12 . A method of characterizing a work piece having crystal grains, the crystal grains having crystal planes having a crystal plane orientation, comprising:
scanning an ion beam across a region of the work piece to determine grain boundaries, the region including multiple crystal grains and the ion beam causing the emission of secondary electrons at multiple imaging points of the scan, the number of secondary electrons emitted at each point of the scan varying with the angle between the ion beam and the crystal planes; detecting the emitted secondary electrons to form an image, the brightness of each point in the image being determined by the number of secondary electrons detected at a corresponding point on the work piece; determining grain boundaries in the work piece using the differences in brightness at different points in the image, the grain boundaries defining multiple grains; acquiring multiple secondary electron images by scanning the ion beam across the region of the work piece multiple times at different angle between the crystal planes and the ion beam; comparing the secondary electron images at the different angles to determine characteristics of the crystal planes; and comparing the characteristics of the crystal planes to reference characteristics of crystal planes of known materials to determine the composition of the grain.

13 . The method of claim 12 in which acquiring multiple secondary electron images by scanning the ion beam across the region of the work piece multiple times comprises scanning fewer points than were scanned to determine grain boundaries.

14 . The method of claim 12 in which acquiring multiple secondary electron images by scanning the ion beam across the region of the work piece multiple times at different angle comprises:
scanning the ion beam at a non-normal angle to the work piece surface; and
rotating the work piece about an axis normal to the work piece surface before detecting the emissions.

15 . The method of claim 12 in which:
comparing the secondary electron images at the different angles to determine characteristics of the crystal planes comprises determining a relationship between the emissions and the orientation angle; and
comparing the characteristics of the crystal planes to reference characteristics of crystal planes of known materials comprises determining the composition or crystal structure of one or more grains based on the detected secondary emissions comprises determining the crystal structure from the relationship between the emissions and the orientation angle.

16 . A charged particle beam system, comprising;
an ion optical source for producing an ion to be directed at a sample; an ion optical column for forming an ion beam from the ions and for focusing an

Assignees

• Fei Co

Inventors

• Randolph Steven
• Rue Chad

Classifications

• G01N23/2257 Primary

  Measuring excited X-rays, i.e. particle-induced X-ray emission [PIXE] · CPC title

• G01N23/2076 Primary

  for spectrometry, i.e. using an analysing crystal, e.g. for measuring X-ray fluorescence spectrum of a sample with wavelength-dispersion, i.e. WDXFS · CPC title