Quality factors in micron- and submicron-thick cantilevers

Citation
Ky. Yasumura et al., Quality factors in micron- and submicron-thick cantilevers, J MICROEL S, 9(1), 2000, pp. 117-125
Citations number
26
Categorie Soggetti
Eletrical & Eletronics Engineeing
Journal title
JOURNAL OF MICROELECTROMECHANICAL SYSTEMS
ISSN journal
10577157 → ACNP
Volume
9
Issue
1
Year of publication
2000
Pages
117 - 125
Database
ISI
SICI code
1057-7157(200003)9:1<117:QFIMAS>2.0.ZU;2-N
Abstract
Micromechanical cantilevers are commonly used for detection of small forces in microelectromechanical sensors (e.g., accelerometers) and in scientific instruments (e.g., atomic force microscopes), A fundamental limit to the d etection of small forces is imposed by thermomechanical noise, the mechanic al analog of Johnson noise, which is governed by dissipation of mechanical energy, This paper reports on measurements of the mechanical quality factor Q for arrays of silicon-nitride, polysilicon, and single-crystal silicon c antilevers. By studying the dependence of Q on cantilever material, geometr y, and surface treatments, significant insight into dissipation mechanisms has been obtained. For submicron-thick cantilevers, Q is found to decrease with decreasing cantilever thickness, indicating surface Loss mechanisms. F or single-crystal silicon cantilevers, significant increase in room tempera ture Q is obtained after 700 degrees C heat treatment in either N-2 or form ing gas. At low temperatures, silicon cantilevers exhibit a minimum in Q at approximately 135K, possibly due to a surface-related relaxation process. Thermoelastic dissipation is not a factor for submicron-thick cantilevers, but is shown to be significant for silicon-nitride cantilevers as thin as 2 .3 mu m. [434].