Stability of wafer level vacuum encapsulated single-crystal silicon resonators

Kaajakari, V.; Kiihamäki, Jyrki; Oja, Aarne; Sepp, H.; Pietikainen, S.; Kokkala, V.; Kuisma, H.

doi:10.1109/sensor.2005.1496567

Cited by 16 publications

(13 citation statements)

References 10 publications

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“…Recent work elsewhere has confirmed that vacuum encapsulation can lead to excellent stability in micromechanical resonators [20]. Demonstration that the encapsulation provides an adequate vacuum is given in the results section.…”

Section: Other Energy Loss Mechanismsmentioning

confidence: 93%

Impact of Geometry on Thermoelastic Dissipation in Micromechanical Resonant Beams

Candler

Duwel

Mathai

et al. 2006

J. Microelectromech. Syst.

134

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Thermoelastic dissipation (TED) is analyzed for complex geometries of micromechanical resonators, demonstrating the impact of resonator design (i.e. slots machined into flexural beams) on TED-limited quality factor. Clarence Zener first described TED for simple beams in 1937. This work extends beyond simple beams into arbitrary geometries, verifying simulations that completely capture the coupled physics that occur. Novel geometries of slots engineered at specific locations within the flexural resonator beams are utilized. These slots drastically affect the thermal-mechanical coupling and have an impact on the quality factor, providing resonators with quality factors higher than those predicted by simple Zener theory. The ideal location for maximum impact of slots is determined to be in regions of high strain. We have demonstrated the ability to predict and control the quality factor of micromechanical resonators limited by thermoelastic dissipation. This enables tuning of the quality factor by structure design without the need to scale its size, thus allowing for enhanced design optimization.

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Section: Other Energy Loss Mechanismsmentioning

confidence: 93%

Impact of Geometry on Thermoelastic Dissipation in Micromechanical Resonant Beams

Candler

Duwel

Mathai

et al. 2006

J. Microelectromech. Syst.

134

View full text Add to dashboard Cite

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“…In general, the 3D integration of MEMS devices can be accomplished by means of throughwafer interconnections. For instance, approaches to fabricate through-wafer vias in a capping wafer have been reported [6,7]. Through-wafer vias embedded inside the substrate of MEMS devices are employed in [8][9][10][11].…”

Section: Introductionmentioning

confidence: 99%

Implementation of silicon-on-glass MEMS devices with embedded through-wafer silicon vias using the glass reflow process for wafer-level packaging and 3D chip integration

Lin

Hsu

Yang

et al. 2008

J. Micromech. Microeng.

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This study presents a novel system architecture to implement silicon-on-glass (SOG) MEMS devices on Si-glass compound substrate with embedded silicon vias. Thus, the 3D integration of MEMS devices can be accomplished by means of through-wafer silicon vias. The silicon vias connecting to the pads of devices are embedded inside the Pyrex glass. Parasitic capacitance for both vias and microstructures is decreased and mismatch of coefficient of thermal expansion (CTE) is reduced. In applications, the glass reflow process together with the SOG micromachining processes were employed to implement the presented concept. Successful driving of the resonator through the silicon vias is demonstrated. The wafer-level hermetic packaging can be further achieved by anodic bonding of a Pyrex7740 wafer. Hermeticity of the packaged device performed by helium leak test satisfied MIL-STD-883E. The packaged SOG device is SMT (surface mount technology) compatible and ready for 3D microsystem integration.

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“…already provides substantial size and power reduction for applications spanning displays, sensors, and fluidic systems, and is now emerging to provide similar advantages for timekeepers and frequency control functions in portable wireless devices [4], [5]. In particular, vibrating micromechanical resonator devices based on silicon micromachining technologies have now been demonstrated with on-chip Q's greater than 10,000 at GHz frequencies [6], [7], frequency-Q products exceeding 2.75×10 13 [6], temperature stability better than 18 ppm over 27 to 107 • C [8], and aging stabilities better than 2 ppm over one year [9], [10]. They have also been embedded into oscillator circuits to achieve phase noise performance satisfying global systems for mobile communications (GSM) specifications for reference oscillators [11]- [13].…”

Section: Introductionmentioning

confidence: 99%

MEMS technology for timing and frequency control

Nguyen¹

Proceedings of the 2005 IEEE International Frequency Control Symposium and Exposition, 2005.

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An overview on the use of microelectromechanical systems (MEMS) technologies for timing and frequency control is presented. In particular, micromechanical RF filters and reference oscillators based on recently demonstrated vibrating on-chip micromechanical resonators with Q's > 10,000 at 1.5 GHz are described as an attractive solution to the increasing count of RF components (e.g., filters) expected to be needed by future multiband, multimode wireless devices. With Q's this high in onchip abundance, such devices might also enable a paradigm shift in the design of timing and frequency control functions, where the advantages of high-Q are emphasized, rather than suppressed (e.g., due to size and cost reasons), resulting in enhanced robustness and power savings. Indeed, as vibrating RF MEMS devices are perceived more as circuit building blocks than as stand-alone devices, and as the frequency processing circuits they enable become larger and more complex, the makings of an integrated micromechanical circuit technology begin to take shape, perhaps with a functional breadth not unlike that of integrated transistor circuits. With even more aggressive three-dimensional MEMS technologies, even higher on-chip Q's are possible, such as already achieved via chip-scale atomic physics packages, which so far have achieved Q's > 10 7 using atomic cells measuring only 10 mm 3 in volume and consuming just 5 mW of power, all while still allowing atomic clock Allan deviations down to 10 ;11 at one hour.

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Stability of wafer level vacuum encapsulated single-crystal silicon resonators

Cited by 16 publications

References 10 publications

Impact of Geometry on Thermoelastic Dissipation in Micromechanical Resonant Beams

Impact of Geometry on Thermoelastic Dissipation in Micromechanical Resonant Beams

Implementation of silicon-on-glass MEMS devices with embedded through-wafer silicon vias using the glass reflow process for wafer-level packaging and 3D chip integration

MEMS technology for timing and frequency control

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