Frequency stability of wafer-scale film encapsulated silicon based MEMS resonators

Kim, Bongsang; Candler, Rob N.; Hopcroft, Matthew A.; Agarwal, M.; Park, Woo-Tae; Kenny, Thomas W.

doi:10.1016/j.sna.2006.10.040

Cited by 129 publications

(64 citation statements)

References 11 publications

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“…Since the in-built heaters are in the device layer with the resonator, no changes to the fabrication process are required to create the thermally isolated DETF. This process ensures a vacuum inside the encapsulation with a pressure of < 1 Pa. Long term (∼1 year) stability of this vacuum condition has also been verified [21]. An optical image and a SEM cross section of encapsulated MEMS resonator with in-built heater is shown in Fig.…”

Section: Fabricationmentioning

confidence: 62%

“…The designs illustrated here are compatible with our previously published "epi-seal" wafer-scale encapsulation process [19], [20]; and all its advantages, such as low leak rate, no requirement for a getter, long-term stability [21], and low-cost manufacturing, are maintained. Designs for thermal isolation with various heating methods will be discussed and compared, before presenting the experimental results of the miniature local-thermal-isolation design.…”

Section: Introductionmentioning

confidence: 60%

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Thermal Isolation of Encapsulated MEMS Resonators

Jha

Hopcroft

Chandorkar

et al. 2008

J. Microelectromech. Syst.

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Abstract-This paper presents an in-chip thermal-isolation technique for a micro-ovenized microelectromechanical-system resonator. Resonators with a microoven can be used for highprecision feedback control of temperature to compensate for the temperature dependence of resonator frequency over a wide temperature range. However, ovenization requires power consumption for heating, and the thermal time constant must be minimized for effective temperature control. This paper demonstrates an efficient local-thermal-isolation mechanism, which can reduce the power requirement to a few milliwatts and the thermal time constant to a few milliseconds. In this method, the mechanical suspension of the resonator is modified to provide thermal isolation and include an integrated resistive heater. This combination provides mechanical suspension, electrical heating, and thermal isolation in a compact structure that requires low heating power and has a small thermal time constant. A power consumption of approximately 12 mW for a 125• C temperature rise and a thermal time constant ranging from 7 to 10 ms is reported in this paper, which is orders of magnitude lower than that of commercially available ovenized quartz resonators. A CMOS-compatible wafer-scale encapsulation process is used to fabricate this device, and the thermal-isolation design is achieved without any modification to the existing resonator fabrication process.[

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Section: Fabricationmentioning

confidence: 62%

Section: Introductionmentioning

confidence: 60%

Thermal Isolation of Encapsulated MEMS Resonators

Jha

Hopcroft

Chandorkar

et al. 2008

J. Microelectromech. Syst.

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show abstract

“…The MEMS resonator was embedded in a feedback loop of a nonlinear circuit to realize an oscillator, which had a short term (τ = 0.6 s) Allan deviation of 0.6 ppb, which is comparable with that of a commercial quartz crystal oscillator. Further improvements in frequency stability could be achieved by incorporating methods for temperature compensation and by vacuum packaging the resonator to reduce ambient pressure fluctuations [11].…”

Section: Discussionmentioning

confidence: 99%

A Single-Crystal-Silicon Bulk-Acoustic-Mode Microresonator Oscillator

Lee

Bahreyni

Zhu

et al. 2008

IEEE Electron Device Lett.

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Abstract-A timing reference incorporating a single-crystalsilicon micromechanical resonator with a quality factor of larger than one million and a resonant frequency of 2.18 MHz is demonstrated. The resonator is excited in the square extensional bulk acoustic mode at 4 mtorr, and it has been fabricated in a foundry SOI MEMS process. The silicon microresonator is adapted as a timing element for a precision oscillator with a measured shortterm Allan deviation of 0.6 ppb.Index Terms-Allan deviation, bulk acoustic resonators, high quality factor, MEMS oscillator, single-crystal silicon (SCS).

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“…This technique, already demonstrated for MEMS oscillators [3], is here proposed for the first time in the field of resonant strain sensors.…”

Section: Introductionmentioning

confidence: 95%

High-resolution strain sensing on steel by Silicon-On-Insulator flexural resonators fabricated with chip-level vacuum packaging

Belsito

Ferri

Mancarella

et al. 2013

2013 Transducers &Amp; Eurosensors XXVII: The 17th International Conference on Solid-State Sensors, Actuators and Microsystems

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This paper reports on the fabrication and characterization of high-resolution strain sensors for steel based on Silicon On Insulator flexural resonators manufactured with chip-level LPCVD vacuum packaging. The sensors present high sensitivity (120 Hz/με), very high resolution (4 nε), low drift, and near-perfect reversibility in bending tests performed in both tensile and compressive strain regimes.

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Frequency stability of wafer-scale film encapsulated silicon based MEMS resonators

Cited by 129 publications

References 11 publications

Thermal Isolation of Encapsulated MEMS Resonators

Thermal Isolation of Encapsulated MEMS Resonators

A Single-Crystal-Silicon Bulk-Acoustic-Mode Microresonator Oscillator

High-resolution strain sensing on steel by Silicon-On-Insulator flexural resonators fabricated with chip-level vacuum packaging

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