Regensburg 2007 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 15: Preparation and characterization
HL 15.3: Vortrag
Montag, 26. März 2007, 17:45–18:00, H13
Determination of potential microdistributions in semiconductors by means of Electron Holography — •Andreas Lenk1, Petr Formanek1, Daniel Wolf1, Hannes Lichte1, and Uwe Mühle2 — 1Institute of Structure Physics, Triebenberg Laboratory, Technische Universitaet Dresden, 01062 Dresden, Germany — 2Qimonda Dresden GmbH & Co. OHG
Nowadays, FIB systems and TEM's are commonly used tools for physical failure analysis in both semiconductor industry and materials research. As a promising extension of TEM, electron holography provides indispensable additional information, such as 2D profiles of variations of the local electrostatic potential in the semiconductor matrix. The distribution of dopants in the material can be calculated from those profiles.
However, like normal TEM, electron holography delivers 2D projections of 3D object information. Artefacts on the object's surface, which were introduced e.g. by the 30kV gallium ions of the FIB during preparation, falsify such projections. For quantitative measurement, it is very important to distinguish between true material properties and artificially generated features.
Therefore, FIB-lamellae have been cross-sectioned and investigated with electron holography. It is shown that the gallium ions of a FIB do not only amorphize the crystalline silicon laterally, but also decrease the electric potential near the surface of the lamella. To understand the corresponding effects on 2D projections, electron holography was combined with tomographic imaging techniques.