Voltage and Dopant Concentration Measurements of Semiconductors using a Band-Pass Toroidal Energy Analyzer Inside a Scanning Electron Microscope

Abstract

This paper presents experimental results obtained from a scanning electron microscope (SEM) second-order focusing toroidal electron energy analyzer attachment. The results demonstrate that the analyzer can be used to obtain high signal-to-noise voltage and dopant concentration measurements on semiconductors in the presence of different electric field conditions at the sample. The experimentally calculated relative error of measurement typically varies from 31 to 63, corresponding to secondary electron (SE) signal mean shifts of 9-18 mV. The millivolt accuracy of these results is over one order of magnitude better than earlier quantitative dopant concentration measurements made by a retarding field analyzer.

Quantitative material analysis using secondary electron energy spectromicroscopy

“…The technique was previously reported as a means of improving the analyser output signal-to-noise ratio, and making the SE peak narrower and more symmetric. It was used to enhance dopant contrast and surface/trapped charge contrast [45][46][47][48] . Figure 1e,f demonstrate how biasing the specimen and its surrounding electrode by − 10 V in this context is similarly capable of enhancing material contrast information at a primary beam voltage of 1 kV, causing the negatively biased Au spectral signal height to be greater than the one for Pt, while making the Pt spectral signal broader than the Au spectral signal, overcoming the inconsistent results of the unbiased case shown in Fig.…”

“…The work reported here utilises a small wide-angle electric toroidal energy analyser SEM attachment design 29 , which has formerly been used to track small changes in the SE energy spectral signal shape for applications such as quantifying dopant concentration 45,46 and mapping interface/surface charge distributions 47,48 . It is used here to perform quantitative material analysis in a variety of different ways.…”