Secondary ion mass spectrometry quantification of boron distribution in an array of silicon nanowires

• Published in: Measurement : journal of the International Measurement Confederation Vol. 211; p. 112630
• Main Authors: Michałowski, Paweł Piotr, Müller, Jonas, Rossi, Chiara, Burenkov, Alexander, Bär, Eberhard, Larrieu, Guilhem, Pichler, Peter
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01-04-2023; Elsevier
• Subjects: Boron; Gate-all-around; Nanowires; Physics; Secondary ion mass spectrometry; Segregation; SIMS; Secondary ion mass spectrometry; Boron; SIMS; Nanowires; Gate-all-around; Segregation; Secondary ion mass spectrometry Segregation
• ISSN: 0263-2241; 1873-412X
• DOI: 10.1016/j.measurement.2023.112630

The development of non-planar structures such as arrays of nanowires (NWs), poses a significant challenge for dopant concentration determination. Techniques that can be readily used for 3D structures usually lack the desired sensitivity whereas secondary ion mass spectrometry (SIMS), known for its excellent detection limits, is designed to analyze flat samples. In this work, we overcome the limitation of standard SIMS approaches. NWs are covered with photoresist forming a flat surface. For high incident angle bombardment, the sputtering process becomes self-flattening, i.e. the ions collide with the sidewalls of the exposed tips of NWs at much lower angles and sputter them significantly faster. Thus, reliable information about the dopant distribution along the height of NWs can be obtained. The SIMS analysis can be performed on an array of 1000 x 1000 nanowires with a detection limit of about 5 x 1016 atoms/cm3 and a reasonable signal-to-noise ratio of about 10 dB.
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•An array of nanowires is covered with photoresist forming a flat surface.•For high incident angle bombardment, the sputtering process becomes self-flattening.•SIMS analysis reveals dopant distribution along the height of nanowires.