A fabrication process for electrostatic microactuators with integrated gear linkages

Legtenberg, R.; Berenschot, J.W.; Elwenspoek, M.; Fluitman, J.H.J.

doi:10.1109/84.623112

Cited by 11 publications

(6 citation statements)

References 25 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The pull-down behavior of the curved electrostatic actuators was a strong function of the initial curvature of the electrodes. It was shown by Legtenberg et al 12 that the second derivative of the total potential energy with respect to polynomial order, n, is negative for n р 2, indicating unstable behavior. The actuators with movable electrodes created by deposition of 0.1 m of hard gold showed an initial curvature of polynomial order 2.…”

Section: Discussionmentioning

confidence: 99%

“…10 The stable behavior of the electrostatic actuator can also be improved by incorporating curvature to the electrodes. Legtenberg et al 12 have shown that the pull-down behavior of the curved electrostatic actuator depends on the shape of the curved electrode. Stable behavior with relatively large displacements and forces can be generated by curved electrodes where curvature with length can be described by a polynomial order greater than 2.…”

mentioning

confidence: 99%

See 1 more Smart Citation

Electrostatic Actuators with Intrinsic Stress Gradient

Chinthakindi

Kohl

2002

J. Electrochem. Soc.

View full text Add to dashboard Cite

Electrostatic actuators are used as voltage-controlled oscillators or resonators in high frequency applications. The change in deflection of a cantilever beam due to an applied voltage leads to change in capacitance between the plates of the beam. However, the range of operation of these devices is limited due to the nonlinear nature of the applied electrostatic forces as the cantilever beam moves. The pull-down instability of the beam limits the travel distance of elastically suspended parallel-plate electrostatic actuators to about one-third of the initial gap distance. The movement of curved actuators under application of an electrostatic force is investigated. The initial curvature of the movable electrode was established by using a built-in stress gradient in the metallic cantilever-beam. A two-dimensional, semi-analytical, finite difference model was used to simulate the behavior of the devices. Three-dimensional modeling was also performed to understand the movement of the cantilever beams. The pull-down voltage of the beams was studied as a function of initial tip deflection, shape of the movable electrode, and anchor type. The stable range of operation of these cantilever beams before pull-down was found to be smaller than one third of the tip deflection. After pull-down, the movable electrode was found to ''uncurl'' upon further application of voltage. This was attributed to the higher order curvature of the movable electrode with large built-in stress gradient.Microelectromechanical systems ͑MEMS͒ is a technology which leverages the existing state-of-the art integrated circuit ͑IC͒ fabrication technology and enables the batch fabrication of miniature mechanical structures, devices, and systems. 1-5 This technology exhibits advantages such as cost reduction through batch fabrication, device-to-device consistency, and performance advancements from dimensional downscaling leading to size and weight reduction. Several MEMS devices, which have been successfully commercialized, include microsensors, micro-optics, pressure sensors, accelerometers, and ink-jet nozzles. 2-4 Emerging applications for MEMS are in the areas of optics, microfluidics, and wireless communications. 2 Most of the MEMS designs use electrostatic, piezoelectric, thermal, pneumatic, or magnetic actuation to move the micromachined parts. 2,3 Due to the availability of large electrostatic forces and high energy densities, electrostatic actuation has advantages as compared to other actuation mechanisms. In most electrostatic actuators, the balance between the electrostatic force and the mechanical restoring force controls the deflection of the electrodes. Upon application of the voltage, a continuous movement of the electrodes is desirable for tuning applications. 6-10 Unfortunately, the range of continuous motion of the electrostatically actuated beam is limited due to the presence of nonlinear electrostatic forces. This leads to the well-known ''pull-down'' instability in these devices, which prevents the stable positioning of the electrode...

show abstract

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

Electrostatic Actuators with Intrinsic Stress Gradient

Chinthakindi

Kohl

2002

J. Electrochem. Soc.

View full text Add to dashboard Cite

show abstract

“…A simple description of diffusion is given by Fick's laws: the molar flux due to diffusion is proportional to the concentration gradient. This can be described by the following formula [31]:…”

Section: The Principle Of Cfsmentioning

confidence: 99%

“…The CFS method can avoid the formation of a liquid-air interface as well as the influence of surface tension. The cyclohexane solution with a phase transition temperature of 6.5 °C and low surface tension is chosen as the medium in the CFS method [30][31][32]. Nitrogen gas was introduced to increase the surface convection and sublimation rate of solid cyclohexane.…”

Section: Introductionmentioning

confidence: 99%

Fabrication and release of silicon nitride micro string array by convection freeze sublimation method at atmospheric pressure

Chen

Zhong

2018

J. Micromech. Microeng.

View full text Add to dashboard Cite

A convection freeze sublimation (CFS) method was developed to release silicon nitride strings with a high aspect ratio and high tensile stress, which are widely applied as electromechanical resonators. This method is cost-efficient and easy to operate for its implementation at atmospheric pressure and no vacuum or cryogenic equipment is needed. The CFS system is composed of cyclohexane, nitrogen gas, a freezer and a drying chamber. Cyclohexane with low surface tension (24.38 mN m−1) and high phase transition temperature (6.5 °C) was chosen as the medium in the CFS method. Nitrogen gas was introduced into the drying chamber to facilitate the sublimation of solid cyclohexane by enhancing heat convection at the solid–air interface. A convective mass transfer model was calculated to quantitatively analyze the influence of convective parameters on the sublimation rate. The silicon nitride string array were successfully released with the aid of 3 ml min−1 flow of nitrogen gas. However, when the nitrogen flow rate exceeded 6 ml min−1, the strings adhered in some points because solid cyclohexane is prone to melt instead of sublimating under excessive heat introduced by nitrogen gas. Furthermore, a finite element model was built to explore the influence of different outlet parameters on the magnitude and uniformity of flow field on the surface of solid cyclohexane. To evaluate the mechanical property of the released string, we measured the natural frequency of a single string and confirmed the influence of tensile stress on its natural frequency. The results showed that the CFS method is able to serve as a general tool for ultra-weak structure releasing, which makes this method applicable in fields such as optomechanics and metamaterials.

show abstract

“…la). For example, the micro x-y-z stage carrying an STM tip [2], the vibrating gyroscope [3] or the micro-gear [4] are all MEMS with several mechanical components interacting with each other in the plane of the wafer.…”

Section: Introduction: In-plane Dof Vs Out Of Plane Dofmentioning

confidence: 99%

Direct integration (DI) of solid state stress sensors with single crystal micro-electro-mechanical systems for integrated displacement sensing

Haronian

1999

Technical Digest. IEEE International MEMS 99 Conference. Twelfth IEEE International Conference on Micro Electro Mechanical Syst

View full text Add to dashboard Cite

MEMS with planar degree of freedom show grate promise as they allow devices with variety of abilities. Still sensing displacements in the plane of the wafer is a complicated task as the sidewalls of the structures are not visible to the photolithography process. This paper introduces one solution to this disadvantage by Direct Integration (DI) of stress sensors made of pn diodes and MOS transistors with MEMS made of micro-beams with planar degree of freedom.Micro-beams with typical cross section of 2 pm x 20 pm are fabricated from single crystal silicon using SCREAM [l] (Single Crystal Reactive Ion Etching and Metalization), process. Sensors are integrated the support of the beams close to their roots. A finite element analysis shows that deformation of the beams induces stress that extends into the support of the beams. By modulating the band gap energy this stress affects the I-V transfer function of the sensor located at the support. This band gap modulation results in modulating secondary properties of solid state devices such as the intrinsic concentration, the charge carrier concentration, the built-in p n junction potential, the junction width, and the mobility of holes and electrons through the piezoresistance tensor.In this paper the DI concept is demonstrated by implementing planar accelerometers and flow sensors that are based on integration with pn diodes and with nMOS transistors. Accelerometers with sensitivity as high as 326 mv/g and flow sensor with amplitude and frequency sensitivities as high as 58 mv/ml/s and 250 Hdml/s are demonstrate.

show abstract

A fabrication process for electrostatic microactuators with integrated gear linkages

Cited by 11 publications

References 25 publications

Electrostatic Actuators with Intrinsic Stress Gradient

Electrostatic Actuators with Intrinsic Stress Gradient

Fabrication and release of silicon nitride micro string array by convection freeze sublimation method at atmospheric pressure

Direct integration (DI) of solid state stress sensors with single crystal micro-electro-mechanical systems for integrated displacement sensing

Contact Info

Product

Resources

About