Page 64 - Principles and Applications of NanoMEMS Physics

2. NANOMEMS PHYSICS: Quantum Wave-Particle Phenomena 51

charge is added, and amplitude proportional to the slope of the voltage
source. This leads to the important observation [67] that a low-impedance
ideal TL in the discrete charge regime will exhibit current flow dominated
by Coulomb blockade.
Clearly, as limiting cases, typifying the behavior of ideal high- and low-
impedance TLs in the discrete charge regime, the phenomena of persistent
currents and Coulomb blockade-type current flow, respectively, raise serious
questions in the context of achieving low-noise analog and reliable digital
circuits and systems at nanometric-length scales. As a result, complete
awareness of the possibility that these features might be inadvertently
included in the design space must be incorporated in TL/interconnect models
utilized in the design and analysis of future NanoMEMS.

2.2.2 Effects of Charge Discreteness in Electrostatic Actuation

One of the distinguishing features of NanoMEMS is the inclusion of
functions based on mechanical structures that can be actuated. For a variety
of reasons, in particular, its compatibility with IC processes, electrostatic
actuation is the actuation mechanism of choice for these devices [48], and is
the one on which we focus our attention next.

2.2.2.1 Fundamental Electrostatic Actuation
Perhaps the most fundamental electrostatically-actuated elements/building
blocks are the singly-(cantilever) and doubly-anchored beams [52], Figure 3.

Figure 2-3. (a) Cantilever beam. (b) Doubly-anchored beam.