Investigation of attractive forces between PECVD silicon nitride microstructures and an oxidized silicon substrate

Scheeper, P.R. and Voorthuyzen, J.A. and Olthuis, W. and Bergveld, P. (1992) Investigation of attractive forces between PECVD silicon nitride microstructures and an oxidized silicon substrate. Sensors and Actuators A: Physical, 30 (3). pp. 231-239. ISSN 0924-4247

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Abstract:	A troublesome phenomenon encountered during the realization of free-standing microstructures, for example, beams, diaphragms and micromotors, is that initially released structures afterwards stick to the substrate. This effect may occur during wafer drying after the etching process has been completed, as well as during normal operation as soon as released structures come into contact with the substrate. In this paper the most important types of attractive forces are discussed with respect to their possible influence on the performance of micromachined structures. It is concluded that the main reason for sticking of PECVD silicon nitride micromachined structures is adsorption of water molecules. The water molecules, adsorbed on both surfaces, attract each other as soon as the surfaces come into contact. It is shown that a chemical surface modification, in order to achieve hydrophobic surfaces, is an effective method for avoiding adsorption of water, and therefore reduces sticking. Sticking of micromachined structures during drying is reduced by rinsing with a non-polar liquid before wafer drying.
Item Type:	Article
Copyright:	© 1992 Elsevier Science
Faculty:	Electrical Engineering, Mathematics and Computer Science (EEMCS)
Research Group:	Biomedical and Environmental Sensor systems (BIOS)
Link to this item:	http://purl.utwente.nl/publications/15312
Official URL:	http://dx.doi.org/10.1016/0924-4247(92)80126-N
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