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Proceedings Paper

Fabrication of vertical nanowire resonators for aerosol exposure assessment
Author(s): Stephan Merzsch ; Hutomo Suryo Wasisto; Andrej Stranz ; Peter Hinze ; Thomas Weimann ; Erwin Peiner ; Andreas Waag
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Paper Abstract

Vertical silicon nanowire (SiNW) resonators are designed and fabricated in order to assess exposure to aerosol nanoparticles (NPs). To realize SiNW arrays, nanolithography and inductively coupled plasma (ICP) deep reactive ion etching (DRIE) at cryogenic temperature are utilized in a top-down fabrication of SiNW arrays which have high aspect ratios (i.e., up to 34). For nanolithography process, a resist film thickness of 350 nm is applied in a vacuum contact mode to serve as a mask. A pattern including various diameters and distances for creating pillars is used (i.e., 400 nm up to 5 μm). In dry etching process, the etch rate is set high of 1.5 μm/min to avoid underetching. The etch profiles of Si wires can be controlled aiming to have either perpendicularly, negatively or positively profiled sidewalls by adjusting the etching parameters (e.g., temperature and oxygen content). Moreover, to further miniaturize the wire, multiple sacrificial thermal oxidations and subsequent oxide stripping are used yielding SiNW arrays of 650 nm in diameter and 40 μm in length. In the resonant frequency test, a piezoelectric shear actuator is integrated with the SiNWs inside a scanning electron microscope (SEM) chamber. The observation of the SiNW deflections are performed and viewed from the topside of the SiNWs to reduce the measurement redundancy. Having a high deflection of ~10 μm during its resonant frequency of 452 kHz and a low mass of 31 pg, the proposed SiNW is potential for assisting the development of a portable aerosol resonant sensor.

Paper Details

Date Published: 17 May 2013
PDF: 7 pages
Proc. SPIE 8763, Smart Sensors, Actuators, and MEMS VI, 87630V (17 May 2013); doi: 10.1117/12.2016932
Show Author Affiliations
Stephan Merzsch , Braunschweig Univ. of Technology (Germany)
Hutomo Suryo Wasisto, Braunschweig Univ. of Technology (Germany)
Andrej Stranz , Braunschweig Univ. of Technology (Germany)
Peter Hinze , Physikalisch-Technische Bundesanstalt (Germany)
Thomas Weimann , Physikalisch-Technische Bundesanstalt (Germany)
Erwin Peiner , Braunschweig Univ. of Technology (Germany)
Andreas Waag , Braunschweig Univ. of Technology (Germany)

Published in SPIE Proceedings Vol. 8763:
Smart Sensors, Actuators, and MEMS VI
Ulrich Schmid; José Luis Sánchez de Rojas Aldavero; Monika Leester-Schaedel, Editor(s)

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