Design considerations for micromachined electric actuators

Abstract This paper provides a perspective on the design and fabrication of surface-micromachined actuators. An analysis of electromagnetic to mechanical energy conversion indicates that electric drive is preferable to magnetic drive for these microactuators. Planar rotary and linear microactuators can be fabricated by selectively etching multi-layer thin-film sandwiches, with the potential for gaps on the order 1 μm and lateral dimensions on the order of 300 μm. Prototype designs are presented for rotary variable-capacitance and induction micromotors. Rotor speeds of 2.4 × 10 5 rad s −1 (2.3 × 10 6 rpm) and accelerations of 2.9 × 10 9 rad s −2 appear feasible for both. In conclusion, some of the research problems in developing a microactuator technology are identified, including warpage of microstructural films due to residual stress, friction between micromachined surfaces and electric breakdown in small gaps.

[1]  R. Muller,et al.  Pin joints, gears, springs, cranks, and other novel micromechanical structures , 1987 .

[2]  H. Nathanson,et al.  The resonant gate transistor , 1967 .

[3]  J. Seto.  The electrical properties of polycrystalline silicon films , 1975 .

[4]  K. Wise,et al.  A high-yield IC-compatible multichannel recording array , 1985, IEEE Transactions on Electron Devices.

[5]  G. Quincke,et al.  Ueber Rotationen im constanten electrischen Felde , 1896 .

[6]  K. Bean,et al.  Anisotropic etching of silicon , 1978, IEEE Transactions on Electron Devices.

[7]  S. Iwamura,et al.  Rotating MNOS disk memory device , 1981, IEEE Transactions on Electron Devices.

[8]  D. W. Burns,et al.  Fabrication techniques for integrated sensor microstructures , 1986, 1986 International Electron Devices Meeting.

[9]  J. Ubbink.  Optimization of the rotor surface resistance of the asynchronous electrostatic motor , 1970 .

[10]  T. Nishimura,et al.  Concept and basic technologies for 3-D IC structure , 1986, 1986 International Electron Devices Meeting.

[11]  S. Middelhoek,et al.  Smart sensors: when and where? , 1985 .

[12]  M.S. Adler,et al.  New high voltage IC technology , 1984, 1984 International Electron Devices Meeting.

[13]  S. Earnshaw.  On the Nature of the Molecular Forces which Regulate the Constitution of the Luminiferous Ether , .

[14]  K.H. Lee,et al.  Integrable high voltage CMOS: Devices, process application , 1985, 1985 International Electron Devices Meeting.

[15]  John G Trump.  Vacuum electrostatic engineering , 1933 .

[16]  K. Petersen,et al.  Fabrication of an integrated, planar silicon ink-jet structure , 1979, IEEE Transactions on Electron Devices.

[17]  K. J. Gabriel,et al.  Design considerations for a practical electrostatic micro-motor , 1987 .

[18]  D. A. Dunn,et al.  A surface-charge induction motor , 1971 .

[19]  H.W. Becke,et al.  Approaches to isolation in high voltage integrated circuits , 1985, 1985 International Electron Devices Meeting.

[20]  Roger T. Howe,et al.  Polycrystalline and amorphous silicon micromechanical beams: annealing and mechanical properties , 1983 .

[21]  K.E. Petersen,et al.  Silicon sensor technologies , 1985, 1985 International Electron Devices Meeting.

[22]  S. Terry,et al.  A gas chromatographic air analyzer fabricated on a silicon wafer , 1979, IEEE Transactions on Electron Devices.

[23]  R. Howe,et al.  Resonant-microbridge vapor sensor , 1986, IEEE Transactions on Electron Devices.

[24]  W. A. Fate.  High‐temperature elastic moduli of polycrystalline silicon nitride , 1975 .

[25]  C. Kooy.  Torque on a resistive rotor in a quasi electrostatic rotating field , 1969 .

[26]  Hideo Yoshihara,et al.  Silicon Nitride Single-Layer X-Ray Mask , 1981 .

[27]  K.E. Petersen,et al.  Silicon as a mechanical material , 1982, Proceedings of the IEEE.

[28]  K. Suzuki,et al.  MOS Integrated silicon pressure sensor , 1985, IEEE Transactions on Electron Devices.

[29]  F. Paschen,et al.  Ueber die zum Funkenübergang in Luft, Wasserstoff und Kohlensäure bei verschiedenen Drucken erforderliche Potentialdifferenz , 1889 .

[30]  W. Braunbek,et al.  Freischwebende Körper im elektrischen und magnetischen Feld , 1939 .

[31]  R. Howe,et al.  Polycrystalline Silicon Micromechanical Beams , 1983 .

[32]  M. Peisl,et al.  Conductivity in polycrystalline silicon—physics and rigorous numerical treatment , 1983, IEEE Transactions on Electron Devices.

[33]  D. W. Burns,et al.  A simple technique for the determination of mechanical strain in thin films with applications to polysilicon , 1985 .

[34]  K. Petersen.  Dynamic micromechanics on silicon: Techniques and devices , 1978, IEEE Transactions on Electron Devices.