Nanoelectromechanical relay without pull-in instability for high-temperature non-volatile memory

Abstract

Emerging applications such as the Internet-of-Things and more-electric aircraft require electronics with integrated data storage that can operate in extreme temperatures with high energy efficiency. As transistor leakage current increases with temperature, nanoelectromechanical relays have emerged as a promising alternative. However, a reliable and scalable non-volatile relay that retains its state when powered off has not been demonstrated. Part of the challenge is electromechanical pull-in instability, causing the beam to snap in after traversing a section of the airgap. Here we demonstrate an electrostatically actuated nanoelectromechanical relay that eliminates electromechanical pull-in instability without restricting the dynamic range of motion. It has several advantages over conventional electrostatic relays, including low actuation voltages without extreme reduction in critical dimensions and near constant actuation airgap while the device moves, for improved electrostatic control. With this nanoelectromechanical relay we demonstrate the first hightemperature non-volatile relay operation, with over 40 non-volatile cycles at 200 ∘ C.

Theory, Design, and Characterization of Nanoelectromechanical Relays for Stiction-Based Non-Volatile Memory

“…The sensitivity changes as a function of the device as the trajectory of the beam is not perfectly circular (given that the hinge is only an approximation of a perfect pivot). This deviation of the trajectory from a perfect circle, though, is small enough that there is no snap in of the beam as discussed in our previous work [14].…”

“…The rotational NEM relay considered here [14] consists of a semicircular beam anchored at or near its geometric center, and four arcuate gates where the beam and gate arcs are concentric (see Fig. 1(a) for an example of a fabricated device).…”

“…1(d)). The advantage conferred by this architecture is that a near constant airgap is maintained as the beam rotates, and thus electromechanical pull-in instability is avoided, as discussed in our previous work [14]. In the following sections we develop from first principles an entirely new model governing both programming and reprogramming using a simpler, yet more accurate and physically intuitive approach than the original model (see [14], supplementary material).…”

“…Non-volatile operation of NEM relays has been demonstrated using a variety of designs and schemes, including charge storage in a floating gate to alter the pull-in voltage [9], [10], and stiction between contacting surfaces [11], [12], [13]. We recently demonstrated a stiction-based bistable NEM relay with a semicircular beam that eliminates electromechanical pull-in instability [14], allowing precise electrostatic control of the beam when switching between two stable states (please see Table 1 in [14] for a comparison between electrostatic nonvolatile relays). As a result, the device has great potential to serve as a non-volatile memory cell.…”

Microcantilever: Dynamical Response for Mass Sensing and Fluid Characterization

“…To partially overcome these drawbacks, alternative physical sources have been considered to generate the driving force, with the aim of moving the point of excitation closer to the cantilever free end and minimizing mode coupling with the surrounding fluid. A common proposed technique is magnetic excitation [32], but nowadays thermal excitation, via an additional laser shining on the microcantilever [33] or by thermal effects in bi-layer cantilevers [34], and piezoelectric [35] or electrostatic [36] excitations are also commonly used for exciting the microdevices. With the point of application of the exciting force being co-located with the detection point (typically the cantilever tip), there is no need for a travelling wave to be formed in the probe and therefore the delay/phase-shift between excitation and deflection is minimized and there is very limited coupling with fluid vibratory modes.…”