Material characterization using ion channeling imaging

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; anddetecting 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.

Description

TECHNICAL FIELD OF THE INVENTION[0001]The present invention relates to material characterization of a sample using high resolution ion channeling imaging.BACKGROUND OF THE INVENTION[0002]Samples, such as mineral samples and other work pieces, are analyzed using a variety of different techniques. In electron backscatter diffraction (EBSD), an electron beam dwells at a point on the work piece surface. Electrons that are backscattered near the surface are diffracted after scattering off crystal planes in the sample. The backscattered electrons are detected to form an image of a diffraction pattern. The diffraction pattern can be indexed and used to identify the crystal structure of the work piece at the dwell point. From the diffraction pattern, the crystal structure of the work piece at the dwell point can be determined. When an investigator has some idea of the materials that make up the work piece, the investigator can match the crystal structure determined by EBSD with the known cr...

AI Technical Summary

Benefits of technology

The technical effect of this patent is to provide a way to map the properties of crystal grains faster and more accurately.

Problems solved by technology

To map a surface by EDS or EBSD is time consuming These techniques require relatively long dwell times at each dwell point to achieve good signal-to-noise ratios for obtaining high resolution grain and / or compositional images of the sample.

The large surface area increases the time to map each surface, rendering high resolution mapping by EDS or EBSD impractically slow.

The surface can be mapped more quickly by measuring fewer dwell point by spacing the dwell points further apart or by reducing the dwell time, but the resulting image is coarse or fuzzy because insufficient data is acquired to produce a high resolution image.

Grains composed of materials having similar average atomic numbers may also be difficult to identify.

The resolution of a SIM image is typically worse than the resolution of a scanning electron microscope (SEM) image.

The mass of the ions will inevitably result in some damage to the sample.

Also, the ions implanted into the work piece can affect some of the properties of the work piece.

Images