シリコン結晶中のヒ素ドーパント原子検出

概要

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In very shallow silicon transistor, it has been required to detect individual dopant atoms. High angle annular dark field (HAADF) image is a powerful tool for composition analysis at an atomic level, but it has been two-dimensional information. Recently, aberration corrected electron microscope has been developed, which enable us to have an electron probe with large convergent angle. Such a probe has been pointed out to improve not only transverse resolution but also depth resolution on a nanometer scale. We found that the column intensity in the HAADF image depended on the z-position of arsenic (As) dopant atoms on the condition that the specimen was very thin and the incident electron beam was irradiated along the [001] direction of the silicon crystal. It means that the position of As dopant atom can be determined three-dimensionally. This is an advantage of obtaining three dimensional distribution of As dopant atoms in the silicon crystal and also finding which type of dopant cluster is formed.
2011-04-20