Probing contact-mode characteristics of silicon nanowire electromechanical systems with embedded piezoresistive transducers

Abstract

This article reports on a new method of monitoring nanoscale contacts in switches based on nanoelectromechanical systems, where the contact-mode switching characteristics can be recorded with the sensitive embedded piezoresistive (PZR) strain transducers. The devices are manufactured using state-of-the-art wafer-scale silicon-on-insulator technology featuring suspended silicon cantilevers and beams as switching elements and sub-100 nm thin silicon nanowires (SiNWs) as PZR transducers. Several different device configurations are studied, including mechanically 'cross'-shaped ('+'), coupled cantilever-SiNW structures, with and without local drain electrodes, and doubly clamped SiNW beams. Through detailed measurement and analysis, we demonstrate that the PZR transducers can enable detection of both mechanical and tunneling switching with multiple repeatable cycles. With the strong PZR effects in thin SiNWs, this type of device could be valuable especially for monitoring cold switching events, and when conventional direct readout of the switching events from the local gate or drain electrodes would not be efficient or sensitive, as nanoscale contacts may not be highly conductive, or may be degrading over time.

Review: Electrostatically actuated nanobeam-based nanoelectromechanical switches – materials solutions and operational conditions

“…Comparable relatively high Young’s moduli (Si, 130–188 GPa [ 129 ] and Ge, 103–150 GPa) [ 130 – 131 ] make these materials useful for applications in NEM devices. Due to the possibility of anisotropic etching, Si is widely used in top-down fabrication of NEM switches [ 20 – 22 50 , 132 ]. Top-down Si-based NEM devices of different designs (for example, U-shaped dual-beam structure with capacitive paddle ( Fig.…”

“…Top-down Si-based NEM devices of different designs (for example, U-shaped dual-beam structure with capacitive paddle ( Fig. 11 ) [ 20 ], torsional [ 133 ]) are typically fabricated from single- or polycrystalline Si substrates using a SiO 2 layer as a sacrificial material to release free-standing elements [ 20 – 22 50 , 132 – 133 ]. 3T Si-based NEM switches can operate at jump-in voltages as low as 0.8 V [ 20 ].…”

The study of radiation effects in emerging micro and nano electro mechanical systems (M and NEMs)

“…The SiC NEMS switch is shown in Figure 6. In parallel to SiC, CWRU and CEA-Leti groups have also jointly developed novel Si nanowire NEMS logic switches ( Figure 7) in which ultrasensitive piezoresistive readout [59]- [61] provides an additional new means for the real-time monitoring of nanoscale contact properties and device characteristics evolution during long cycles. CWRU has developed unique and genuinely nanoscale electromechanical switching devices with both two-and three-terminal structures.…”

Electrodynamic Force, Casimir Effect, and Stiction Mitigation in Silicon Carbide Nanoelectromechanical Switches

“…For switches where genuinely nanoscale contacts are crucial determinants of the performance, stiction between interfaces due to quantum mechanical electrodynamic force (EDF) or Casimir effect has become an ultimate factor compromising the device. [10,11] EDF, usually known as van der Waals force (at shorter range) or Casimir force (at longer range), originates from the modification of quantum and thermal fluctuations of the electromagnetic (EM) field due to dielectric material boundaries. [12][13][14] Quantum fluctuations of EM field are highly intriguing quantum effects with a number of observable consequences at mesoscopic scale, in micro/nanofabricated devices.…”

“…For switches where genuinely nanoscale contacts are crucial determinants of the performance, stiction between interfaces due to quantum mechanical electrodynamic force (EDF) or Casimir effect has become an ultimate factor compromising the device. [ 10,11 ]…”