Analysis of the performance of methods to enhance the spatial resolution of measurements collected by a microwave probe

There is increasing interest in X-ray microanalysis of thin specimens and the present paper attempts to define some of the factors which govern the spatial resolution of this type of microanalysis. One of these factors is the spreading of the electron probe as it is transmitted through the specimen. There will always be some beam-spreading with small electron probes, because of the inevitable beam divergence associated with small, high current probes; a lower limit to the spatial resolution is thus 2αst where 2αs is the beam divergence and t the specimen thickness.In addition there will of course be beam spreading caused by elastic and inelastic interaction between the electron beam and the specimen. The angle through which electrons are scattered by the various scattering processes can vary from zero to 180° and it is clearly a very complex calculation to determine the effective size of the beam as it propagates through the specimen.

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Precipitation in silicon: Microanalysis

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100104431 ◽

1988 ◽

Vol 46 ◽

pp. 474-475

Author(s):

R.W. Carpenter

Keyword(s):

Transition Metals ◽

Spatial Resolution ◽

Thin Foil ◽

Precipitation Reaction ◽

High Current ◽

Reaction Products ◽

Carbon And Nitrogen ◽

Dielectric Layers ◽

Precipitation Processes ◽

Areas Of Interest

Interest in precipitation processes in silicon appears to be centered on transition metals (for intrinsic and extrinsic gettering), and oxygen and carbon in thermally aged materials, and on oxygen, carbon, and nitrogen in ion implanted materials to form buried dielectric layers. A steadily increasing number of applications of microanalysis to these problems are appearing. but still far less than the number of imaging/diffraction investigations. Microanalysis applications appear to be paced by instrumentation development. The precipitation reaction products are small and the presence of carbon is often an important consideration. Small high current probes are important and cryogenic specimen holders are required for consistent suppression of contamination buildup on specimen areas of interest. Focussed probes useful for microanalysis should be in the range of 0.1 to 1nA, and estimates of spatial resolution to be expected for thin foil specimens can be made from the curves shown in Fig. 1.

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High spatial resolution x-ray microanalysis of interfaces

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100137793 ◽

1995 ◽

Vol 53 ◽

pp. 284-285

Author(s):

J. R. Michael

Keyword(s):

Spatial Resolution ◽

Electron Probe ◽

Solid Angle ◽

Collection Efficiency ◽

Spatial Scales ◽

Energy Dispersive Spectrometer ◽

X Rays ◽

X Ray ◽

Probe Size ◽

Brightness Field

X-ray microanalysis in the analytical electron microscope (AEM) refers to a technique by which chemical composition can be determined on spatial scales of less than 10 nm. There are many factors that influence the quality of x-ray microanalysis. The minimum probe size with sufficient current for microanalysis that can be generated determines the ultimate spatial resolution of each individual microanalysis. However, it is also necessary to collect efficiently the x-rays generated. Modern high brightness field emission gun equipped AEMs can now generate probes that are less than 1 nm in diameter with high probe currents. Improving the x-ray collection solid angle of the solid state energy dispersive spectrometer (EDS) results in more efficient collection of x-ray generated by the interaction of the electron probe with the specimen, thus reducing the minimum detectability limit. The combination of decreased interaction volume due to smaller electron probe size and the increased collection efficiency due to larger solid angle of x-ray collection should enhance our ability to study interfacial segregation.

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Scanning x-ray fluorescence microscopy and principal component analysis

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100133394 ◽

1992 ◽

Vol 50 (2) ◽

pp. 1752-1753

Author(s):

Brian Cross

Keyword(s):

Principal Component Analysis ◽

Fluorescence Microscopy ◽

Spatial Resolution ◽

High Speed ◽

Image Acquisition ◽

Principal Component ◽

Fluorescence Microscope ◽

Acquisition Rate ◽

X Ray ◽

Speed Up

A relatively new entry, in the field of microscopy, is the Scanning X-Ray Fluorescence Microscope (SXRFM). Using this type of instrument (e.g. Kevex Omicron X-ray Microprobe), one can obtain multiple elemental x-ray images, from the analysis of materials which show heterogeneity. The SXRFM obtains images by collimating an x-ray beam (e.g. 100 μm diameter), and then scanning the sample with a high-speed x-y stage. To speed up the image acquisition, data is acquired "on-the-fly" by slew-scanning the stage along the x-axis, like a TV or SEM scan. To reduce the overhead from "fly-back," the images can be acquired by bi-directional scanning of the x-axis. This results in very little overhead with the re-positioning of the sample stage. The image acquisition rate is dominated by the x-ray acquisition rate. Therefore, the total x-ray image acquisition rate, using the SXRFM, is very comparable to an SEM. Although the x-ray spatial resolution of the SXRFM is worse than an SEM (say 100 vs. 2 μm), there are several other advantages.

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Quantitative parallel EELS spectrum imaging developed as a new tool in AEM

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010013064x ◽

1992 ◽

Vol 50 (2) ◽

pp. 1202-1203

Author(s):

Gianluigi Botton ◽

Gilles L'espérance

Keyword(s):

Statistical Analysis ◽

Spatial Resolution ◽

Personal Computer ◽

Systematic Study ◽

Present Author ◽

Chemical Elements ◽

Detection Limits ◽

Research Groups ◽

Quantitative Performance ◽

Spectrum Imaging

As interest for parallel EELS spectrum imaging grows in laboratories equipped with commercial spectrometers, different approaches were used in recent years by a few research groups in the development of the technique of spectrum imaging as reported in the literature. Either by controlling, with a personal computer both the microsope and the spectrometer or using more powerful workstations interfaced to conventional multichannel analysers with commercially available programs to control the microscope and the spectrometer, spectrum images can now be obtained. Work on the limits of the technique, in terms of the quantitative performance was reported, however, by the present author where a systematic study of artifacts detection limits, statistical errors as a function of desired spatial resolution and range of chemical elements to be studied in a map was carried out The aim of the present paper is to show an application of quantitative parallel EELS spectrum imaging where statistical analysis is performed at each pixel and interpretation is carried out using criteria established from the statistical analysis and variations in composition are analyzed with the help of information retreived from t/γ maps so that artifacts are avoided.

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Cristal-growth dynamics of n-doped gaAs

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100132352 ◽

1992 ◽

Vol 50 (2) ◽

pp. 1544-1545

Author(s):

Pham V. Huong ◽

Stéphanie Bouchet ◽

Jean-Claude Launay

Keyword(s):

Crystal Growth ◽

Spatial Resolution ◽

Epitaxial Layer ◽

Outer Surface ◽

Gaas Substrate ◽

Structural Modification ◽

Growth Dynamics ◽

Argon Laser ◽

High Anisotropy ◽

Crystal Gaas

Microstructure of epitaxial layers of doped GaAs and its crystal growth dynamics on single crystal GaAs substrate were studied by Raman microspectroscopy with a Dilor OMARS instrument equipped with a 1024 photodiode multichannel detector and a ion-argon laser Spectra-Physics emitting at 514.5 nm.The spatial resolution of this technique, less than 1 μm2, allows the recording of Raman spectra at several spots in function of thickness, from the substrate to the outer deposit, including areas around the interface (Fig.l).The high anisotropy of the LO and TO Raman bands is indicative of the orientation of the epitaxial layer as well as of the structural modification in the deposit and in the substrate at the interface.With Sn doped, the epitaxial layer also presents plasmon in Raman scattering. This fact is already very well known, but we additionally observed that its frequency increases with the thickness of the deposit. For a sample with electron density 1020 cm-3, the plasmon L+ appears at 930 and 790 cm-1 near the outer surface.

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