How to make MEMS and NEMS Over the past six years, at my lab and elsewhere, new techniques have been developed for patterning freely suspended 3-D semiconductor structures. Finally, a local chemically selective etch step removes the sacrificial layer from specific regions to create freely suspended nanostructures that are both thermally and mechanically isolated. In typical devices this entire procedure might be repeated several times and combined with various deposition processes to give complicated mechanical nanostructures. The flexibility of the process allows complex suspended structures with lateral dimensions down to a few tens of nanometres to be fabricated. Moreover, complex transducers can be incorporated for control and measurement purposes.
Epitaxial growth means that the thickness of the layers can be controlled with atomic precision.
In principle, the fabricated devices can be just a few layers thick. Challenges for NEMS Processes such as electron-beam lithography and nanomachining now enable semiconductor nanostructures to be fabricated below 10 nm. NEMS are clearly very small devices that can deflect or vibrate within an even smaller range during operation. For example, the deflection of a doubly clamped beam varies linearly with an applied force only if it is displaced by an amount that typically corresponds to a few per cent of its thickness. For a beam 10 nm in diameter, this translates to displacements that are only a fraction of a nanometre.