Stiction in surface micromachining

Tas, Niels and Sonnenberg, Tonny and Jansen, Henri and Legtenberg, Rob and Elwenspoek, Miko (1996) Stiction in surface micromachining. Journal of Micromechanics and Microengineering, 6 (4). pp. 385-397. ISSN 0960-1317

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Abstract:	Due to the smoothness of the surfaces in surface micromachining, large adhesion forces between fabricated structures and the substrate are encountered. Four major adhesion mechanisms have been analysed: capillary forces, hydrogen bridging, electrostatic forces and van der Waals forces. Once contact is made adhesion forces can be stronger than the restoring elastic forces and even short, thick beams will continue to stick to the substrate. Contact, resulting from drying liquid after release etching, has been successfully reduced. In order to make a fail-safe device stiction during its operational life-time should be anticipated. Electrostatic forces and acceleration forces caused by shocks encountered by the device can be large enough to bring structures into contact with the substrate. In order to avoid in-use stiction adhesion forces should therefore be minimized. This is possible by coating the device with weakly adhesive materials, by using bumps and side-wall spacers and by increasing the surface roughness at the interface. Capillary condensation should also be taken into account as this can lead to large increases in the contact area of roughened surfaces.
Item Type:	Article
Copyright:	© 1996 IEEE
Faculty:	Electrical Engineering, Mathematics and Computer Science (EEMCS)
Research Group:	Transducers Science and Technology (TST)
Link to this item:	http://purl.utwente.nl/publications/14204
Official URL:	http://dx.doi.org/10.1088/0960-1317/6/4/005
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