Whispers of a working chip, page-163

Thanks. The first section sets out the issue pretty well, imo.
'Microelectromechanical systems (MEMS) are very small devices, which are made up of components whose size is in the micrometer scale (e.g. between 0.1 to 100 micrometers in size). MEMS devices generally range in size from 20 to 5,000 micrometers. MEMS include components that interact with the environment of the MEMS such as microsensors or actuators. At the smaller size scales, the standard constructs of classical physics are not always useful.
For example, at large scale implementations (not MEMS) the generally accepted value of the breakdown field strength of air is E≈3 MV/m (≈3 V/μm). At smaller distances, the breakdown voltage depends on gap and pressure. For example, at a pressure of 1 Atmosphere, the minimum breakdown voltage of air over a gap of 7.5 μm is approximately 327V (E=44V/um). At very small gaps (e.g. 0.5 μm), the break down voltage is larger than 2000V (E>4000V/μm).
Due to this fact, relatively small potential differences (e.g. <500V) between any two conductors in a MEMS that may come sufficiently near one another may result in a breakdown of the separating medium between such two conductors. Such breakdown may result in temporary or even permanent damage to the MEMS (e.g. due to high temperature which may result from such a breakdown).
There is therefore a need for microelectromechanical systems whose design overcomes the generation of such electric breakdowns. There is also a need for methods of fabrication and design of such MEMS.....'