Investigation of 20% scandium-doped aluminum nitride films for MEMS laterally vibrating resonators

Colombo, Luca; Kochhar, Abhay; Xu, Cheng; Piazza, Gianluca; Mishin, Sergey; Oshmyansky, Yury

doi:10.1109/ultsym.2017.8092076

Cited by 24 publications

(16 citation statements)

References 1 publication

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“…First, IL of ADLs with more cells is smaller, which is due to more energy propagating toward the FWD caused by more reflectors. Second, the FBW of ADLs with more cells is smaller, which is a direct result of a narrower band transfer function [see (7)]. These two results agree with the IL-FBW tradeoff.…”

Section: Acoustic Delay Lines With Different Fractional Bandwidthssupporting

confidence: 55%

“…Thus, acoustic devices do not compete with the powerhungry analog-to-digital converters (ADCs) and digital signal processors (DSPs) in the follow-on stages for the power budget [6]. Third, the recent development of high electromechanical coupling (k 2 ) piezoelectric platforms [7]- [13] has demonstrated record-low loss over a wide bandwidth (BW), thus overcoming the high insertion loss (IL) and narrow BW bottleneck that have been precluding acoustic signal processing from eMBB applications.…”

Section: Introductionmentioning

confidence: 99%

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GHz Broadband SH0 Mode Lithium Niobate Acoustic Delay Lines

Yang

et al. 2020

IEEE Trans. Ultrason., Ferroelect., Freq. Contr.

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We present the first group of GHz broadband SH0 mode acoustic delay lines (ADLs). The implemented ADLs adopt unidirectional transducer designs in a suspended X-cut lithium niobate thin film. The design space of the SH0 mode ADLs at GHz is first theoretically investigated, showing that the large coupling and sufficient spectral clearance to adjacent modes collectively enable the broadband performance of SH0 delay lines. The fabricated devices show 3-dB fractional bandwidth ranging from 4% to 34.3% insertion loss between 3.4 and 11.3 dB. Multiple delay lines have been demonstrated with center frequencies from 0.7 to 1.2 GHz, showing great frequency scalability. The propagation characteristics of SH0 in lithium niobate thin film are experimentally extracted. The demonstrated ADLs can potentially facilitate broadband signal processing applications.

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Section: Acoustic Delay Lines With Different Fractional Bandwidthssupporting

confidence: 55%

Section: Introductionmentioning

confidence: 99%

GHz Broadband SH0 Mode Lithium Niobate Acoustic Delay Lines

Yang

et al. 2020

IEEE Trans. Ultrason., Ferroelect., Freq. Contr.

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“…Unlike AlN, ScAlN films are highly resistant to BCl3-based RIE recipes, resulting in very low etch rates and poor selectivity to photoresist or silicon dioxide mask layers. Furthermore, the Sc-based non-volatile byproducts of the etching process remains / accumulates during the etching process [8], which results in undesirable nano-masking of subsequent etching of bottom Mo in trenches as well as DRIE of silicon and yields waveguides with rough sidewalls and consequently low Q. To address the etching challenges of ScAlN while sustaining a reasonably low RIE/ICP power and high etching selectivity, a Cl2/H2 based RIE recipe is developed to realize comparable etch rates to AlN thin films.…”

Section: Fabrication Processmentioning

confidence: 99%

“…Although successful in improving the kt 2 , ScAlN Lamb-wave resonators suffer from low Qs that are nearly an order of magnitude lower compared to FBARs at the same frequency. The degradation in Q with Sc doping can be attributed to (a) formation of (100)crystalline inclusions in (002) oriented ScAlN films [6] and (b) nonideal etching profile of the films that results in rough and tapered sidewalls [8].…”

Section: Introductionmentioning

confidence: 99%

HIGH Kt2∙Q LAMB-WAVE SCALN-ON-SILICON UHF AND SHF RESONATORS

Ghatge¹,

Felmetsger²,

Tabrizian³

2018

2018 Solid-State, Actuators, and Microsystems Workshop Technical Digest

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This paper reports, for the first time, on waveguide-based resonators implemented in scandium-doped aluminum nitride-onsilicon (ScAlN-on-Si) stack to simultaneously benefit from large piezoelectric constants of ScAlN and low acoustic dissipation in single crystal silicon. 1m-thick ScAlN film with Sc content of 7% is reactively sputtered on silicon substrates using ac-powered dualtarget S-gun magnetron with Al targets containing embedded pure Sc pellets. A Cl2/H2 based low-power plasma etching recipe is developed to pattern resonators with smooth vertical sidewalls. Inand out-of-plane waveguide-based resonator prototypes with large electromechanical coupling coefficient (kt 2 ) and high quality-factor (Q) are implemented over 80 MHz -3.5 GHz demonstrating kt 2 of 0.7%-2.9% and Q of 2000-6400. Specifically, a high 0 × of 4.3 × 10 12 is measured for a resonator at 3.5 GHz, and a high 2 × of 51 is measured at 108 MHz. The large 2 × of ScAlNon-Si waveguide-based resonators along with lithographical frequency tailorability demonstrate their potential for realization of highly integrated front-end filters for multi-band 5G systems.

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“…Among various MEMS resonator options, laterally vibrating resonators (LVRs) have been garnering most interest for providing the above characteristics when high-performance piezoelectric materials are adopted (i.e. doped Aluminum Nitride (AlN) [12]- [14] or Lithium Niobate (LiNbO3) [15]- [24]).…”

Section: Introductionmentioning

confidence: 99%