A Fully Integrated Quartz MEMS VHF TCXO

Kubena, R. L.; Stratton, F. P.; Nguyen, Hung D.; Kirby, D. J.; Chang, David T.; Joyce, R. J.; Yong, Yook‐Kong; Garstecki, Jeffrey F.; Cross, Matthew D.; Seman, S. E.

doi:10.1109/tuffc.2017.2786248

Cited by 9 publications

(3 citation statements)

References 6 publications

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“…Deep Reactive Ion Etching of quartz has been developed for the last decade thanks to the development of high density plasma etcher. DRIE-made resonators have been reported for various applications such as Quartz Crystal Microbalance (Kutsuwada et al 2017) (Abe & Esashi 2000), gyroscope (Grousset et al 2014) or timing applications (Kubena et al 2017) (Kamijo et al 2014). Vertical etching of quartz over several tens microns is still challenging.…”

Section: Process Flowmentioning

confidence: 99%

High Q 2D-length extension mode resonators for potential time–frequency applications

et al. 2019

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This paper presents recent advances on two dimensional Length-Extension Mode (2D-LEM) quartz resonators providing high quality (Q) factor on resonances at a few MHz. The resonators have been collectively manufactured using one or two steps quartz Deep Reactive-Ion Etching (DRIE) processes. These resonators combine the intrinsic qualities of quartz in comparison to silicon (i.e. high Q factor, low temperature sensitivity and piezoelectricity) and the advantages of Microelectromechanical systems (MEMS) resonators: small dimensions, low power consumption and collective processes. Samples vibrating at frequencies f of 2.2, 3 and 4.5 MHz have shown promising results with very high Q factor. Q factor as high as 180 000 for fundamental mode vibrating at 2.2 MHz and 89 000 for harmonic mode at 8.9 MHz were measured which lead to quality factor and resonance frequency products (Q.f) figure of merit near 10 12 Hz at the state of the art for 2D-LEM quartz resonators and the higher Q factor measured for DRIE made quartz resonators. Two designs, several dimensions and two processes have been investigated. Two main limiting damping mechanisms were identified and one of them is strongly linked to the technological limits of the etching process.

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Section: Process Flowmentioning

confidence: 99%

High Q 2D-length extension mode resonators for potential time–frequency applications

et al. 2019

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“…This facilitates integrating drive and sensing electrodes within a single resonator, thus minimizing alignment errors common in high-end sensors [ 7 ]. Consequently, quartz is widely used in manufacturing MEMS devices [ 8 , 9 ]. In wet etching, quartz crystals are typically etched using saturated ammonium fluoride (NH 4 HF 2 ) or buffered oxide etchant (BOE), the latter being a blend of NH 4 F:HF.…”

Section: Introductionmentioning

confidence: 99%

Etching Rate Analysis Model Based on Quartz Bond Angle Characteristics

Zhao,

Lv,

Song

et al. 2024

Micromachines

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This paper proposes a method for classifying crystal planes based on the bond angle characteristics of quartz unit cells and constructs an etch rate model for quartz crystal planes at both macro and micro scales. By omitting oxygen atoms from the quartz cell structure, a method based on bond angle characteristics was established to partition the atomic arrangement of the crystal surface. This approach was used to analyze the etching processes of typical quartz crystal planes (R, r, m, and (0001)), approximating the etching process of crystals as a cyclic removal of certain bond angle characteristics on the crystal planes. This led to the development of an etch rate model based on micro-geometric parameters of crystal planes. Additionally, using the proposed bond angle classification method, the common characteristics of atomic configurations on the crystal plane surfaces within the X_cut type were extracted and classified into seven regions, further expanding and applying the etch rate model. The computational results of this model showed good agreement with experimental data, indicating the rationality and feasibility of the proposed method. These also provide a theoretical basis for understanding the microstructural changes during quartz-based MEMS etching processes.

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“…To this end, voltage-controlled MEMS oscillators (VCMOs) employing high quality factor (Q) and high electromechanical coupling (kt 2 ) acoustic resonators are emerging as a great enabler for such direct RF synthesis. Unfortunately, the tuning range of a VCMO based on a MEMS resonator is ultimately limited by the resonator kt 2 [1][2][3][4][5].…”

Section: Introductionmentioning

confidence: 99%

A 300-500 MHz Tunable Oscillator Exploiting Ten Overtones in Single Lithium Niobate Resonator

Kourani

Gao

et al. 2019

2019 Joint Conference of the IEEE International Frequency Control Symposium and European Frequency and Time Forum (EFTF/IFC)

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This paper presents the first voltage-controlled MEMS oscillator (VCMO) based on a Lithium Niobate (LiNbO3) lateral overtone bulk acoustic resonator (LOBAR). The VCMO consists of a LOBAR in a closed loop with 2 amplification stages and a varactor-embedded tunable LC tank. By adjusting the bias voltage applied to the varactor, the tank can be tuned to change the closed-loop gain and phase responses of the oscillator so that the Barkhausen conditions are satisfied for a particular resonance mode. The tank is designed to allow the proposed VCMO to lock to any of the ten overtones ranging from 300 to 500 MHz. Owing to the high-quality factors of the LiNbO3 LOBAR, the measured VCMO shows a low close-in phase noise of -100 dBc/Hz at 1 kHz offset from a 300 MHz carrier and a noise floor of -153 dBc/Hz while consuming 9 mW. With further optimization, this VCMO can lead to direct radio frequency (RF) synthesis for ultra-lowpower transceivers in multi-mode Internet-of-Things (IoT) nodes.

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A Fully Integrated Quartz MEMS VHF TCXO

Cited by 9 publications

References 6 publications

High Q 2D-length extension mode resonators for potential time–frequency applications

High Q 2D-length extension mode resonators for potential time–frequency applications

Etching Rate Analysis Model Based on Quartz Bond Angle Characteristics

A 300-500 MHz Tunable Oscillator Exploiting Ten Overtones in Single Lithium Niobate Resonator

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