Thin film processes, MEMS technologies

Thin Film Processes in MEMS and NEMS Technologies... 

Thin film processes and the chemistry of surfaces play important roles in the technological implementation of MEMS and NEMS devices. Thin film deposition of a variety of materials is a mature technology, whereas MEMS surface coating technologies have only recently come of age. 

Auciello O, et al. Materials science and fabrication processes for a new MEMS technology based on ultrananocrystaUine diamond thin films. J Phys Condens Matter 2004. 

These submillimeter devices are machined using specific techniques globally called microfabrication technology. This definition also includes microelectronic devices, but in addition to electronic parts, MEMS also features mechanical parts like holes, cavity, channels, cantilevers, or membranes. This particularity has a direct impact on their manufacturing processes which need to be adapted for thick layer deposition, deep etching and to introduce special steps to free the mechanical structures. Moreover, many MEMS are now not only based on silicon but are also manufaetured with polymer, glass, quartz or thin metal films. 

The term micromachining refers to the mechanical aspect of fabrication processes. MEMS microfabrication techniques, while based on conventional IC fabrication technology, also include more specialized and refined processes which permit the formation of mechanical structures. The key for both MEMS and IC fabrication is photolithography, which permits high volume, batch production of devices with microscale dimensions. In photolithography, a thin, photosensitive polymer film ( photoresist ) is selectively exposed to UV light using a photomask (Fig. 1). 

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