The application of fine-grained, tensile polysilicon to mechanicaly resonant transducers

Guckel, H.; Sniegowski, J.J.; Christenson, Todd R.; Raissi, Farshid

doi:10.1016/0924-4247(90)85069-g

Cited by 134 publications

(38 citation statements)

References 3 publications

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“…When the coupling beam length is much shorter than oneeighth of the flexural-mode wavelength corresponding to the filter center frequency, (27) and (28) reduce to (29) where , and…”

Section: B Casementioning

confidence: 99%

“…13(b) to a chain network described by (22) [15], then solving for the series and shunt impedances in terms of chain matrix elements, yields (27) and (28) The two cases of practical design interest occur when the coupling beam lengths correspond to less than one-eighth wavelength (sub-) and to an effective quarter-wavelength at the filter center frequency. Subdesigns are of interest because they lend themselves more easily to lumped models and are thus analytically simpler to implement than beams with greater lengths.…”

Section: A Coupling Beam Designmentioning

confidence: 99%

“…13(b) take on equal and opposite values, and thus, cancel in each mesh. By inspection of (27) and (28), and take on equal and opposite values when (31) Using the selected value of (in step (1) of Section VI), (31) can be solved for the that corresponds to an effective quarter-wavelength of the operating frequency. With quarterwavelength coupler dimensions, the impedances of Fig.…”

Section: Casementioning

confidence: 99%

“…In addition, two different methods for depositing and doping the polysilicon structural material were utilized to investigate the effect of the doping procedure on resonator : one based on POCl -doping, and the other on implant-doping. deposited at a temperature optimized to yield low-stress, finegrained characteristics [27]. The grains are grown, however, during the subsequent dopant drive-in anneals, which are chosen to attain an acceptable compromise between structural film stress and conductivity.…”

Section: Fabricationmentioning

confidence: 99%

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High-order medium frequency micromechanical electronic filters

Wang

Nguyen

1999

J. Microelectromech. Syst.

175

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Abstract-Third-order, high-Q, micromechanical bandpass filters comprised of three ratioed folded-beam resonators coupled by flexural mode springs are demonstrated using an integrated circuit compatible, doped polycrystalline silicon surfacemicromachining technology. A complete design procedure for multiresonator micromechanical filters is presented and solidified via an example design. The use of quarter-wavelength coupling beams attached to resonators at velocity-controllable locations is shown to suppress passband distortion due to finite-mass and process mismatch nonidealities, which become increasingly important on this microscale. In addition, low-velocity coupling methods are shown to greatly alleviate the lithographic resolution required to achieve a given percent bandwidth. Ratioed foldedbeam micromechanical resonators are introduced as the key impedance transforming components that enable the needed low-velocity coupling. Using these design techniques, balanced three-resonator microscale mechanical filters with passband frequencies centered around 340 kHz are demonstrated with percent bandwidths of 0.1%, associated insertion losses as small as 0.1 dB, 20-dB shape factors as low as 1.5, and stopband rejections greater than 64 dB. Measurement and theory are rigorously compared and important limitations, such as thermal susceptibility, the need for passband tuning, and inadequate electromechanical coupling, are addressed. [470]

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“…When the coupling beam length is much shorter than oneeighth of the flexural-mode wavelength corresponding to the filter center frequency, (27) and (28) reduce to (29) where , and…”

Section: B Casementioning

confidence: 99%

Section: A Coupling Beam Designmentioning

confidence: 99%

Section: Casementioning

confidence: 99%

Section: Fabricationmentioning

confidence: 99%

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High-order medium frequency micromechanical electronic filters

Wang

Nguyen

1999

J. Microelectromech. Syst.

175

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“…The release of structures from within thin-film shells can involve long etch times, since access to the sacrificial layer is from channels located at the perimeter of the shell [34,58,59]. Thin polysilicon able to hydrofluoric acid, when deposited on PSG [60,61].…”

Section: Microstructure Release and Surface Passivationmentioning

confidence: 99%

Recent Advances in Surface Micromachining

Howe

1996

IEEJ Trans. SM

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Abstract-Surface micromachining is the fabrication of micromechanical structures from deposited thin films. Although the process dates to the 1960s, this paper will survey its rapid extension over the past few years and its application to batch-fabrication of micromechanisms and of monolithic micro electromechanical systems (MEMS). Two central issues in surface micromachining are: (i) the understanding and control of the material properties of microstructural films, such as polycrystalline silicon, and (ii) the release of the microstructure, for example by wet-etching silicon dioxide sacrificial films, followed by the drying and surface passivation of the microstructure. Recent developments in hinged structures for postrelease assembly and high-aspect ratio fabrication of molded parts from deposited thin films promise to extend greatly the capabilities of surface micromachining technology.

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