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Sc(0.06)Al(0.94)N film evaluation using contour mode resonators

IEEE International Ultrasonics Symposium, IUS

Griffin, Benjamin G.; Henry, Michael D.; Heinz, Bernd

Recent literature has focused on improving piezoelectric coupling coefficients by alloying aluminum nitride (AlN) with scandium (Sc). Akiyama et al. showed the highest d-33 piezoelectric coefficient increase of >4x at a 41% Sc substitution for Al. Thus far, studies mainly focus on material measurements such as x-ray diffraction or piezoelectric constants to assess the material quality. Although these measurements are useful to assess the improvement in the piezoelectric performance of the material, they do not address improvements in the figure-of-merit (FOM) of resonators (i.e., coupling coefficient times quality factor). Resonator structures are needed to directly extract these key performance parameters for film assessment. Fabrication integration, however, must be minimized to avoid obscuring film performance by extrinsic device effects.

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TYPE Conference Poster YEAR 2017
ScopusOSTI

ScAlN etch mask for highly selective silicon etching

Journal of Vacuum Science and Technology B: Nanotechnology and Microelectronics

Henry, Michael D.; Young, Travis R.; Griffin, Benjamin G.

This work reports the utilization of a recently developed film, ScAlN, as a silicon etch mask offering significant improvements in high etch selectivity to silicon. Utilization of ScAlN as a fluorine chemistry based deep reactive ion etch mask demonstrated etch selectivity at 23 550:1, four times better than AlN, 11 times better than Al2O3, and 148 times better than silicon dioxide with significantly less resputtering at high bias voltage than either Al2O3 or AlN. Ellipsometry film thickness measurements show less than 0.3 nm/min mask erosion rates for ScAlN. Micromasking of resputtered Al for Al2O3, AlN, and ScAlN etch masks is also reported here, utilizing cross-sectional scanning electron microscope and confocal microscope roughness measurements. With lower etch bias, the reduced etch rate can be optimized to achieve a trench bottom surface roughness that is comparable to SiO2 etch masks. Etch mask selectivity enabled by ScAlN is likely to make significant improvements in microelectromechanical systems, wafer level packaging, and plasma dicing of silicon.

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TYPE Journal Article YEAR 2017
ScopusOSTIDOI

Aluminum nitride piezoelectric microphones as zero-power passive acoustic filters

TRANSDUCERS 2017 - 19th International Conference on Solid-State Sensors, Actuators and Microsystems

Reger, Robert W.; Clews, Peggy J.; Bryan, Gwendolyn M.; Keane, Casey A.; Henry, Michael D.; Griffin, Benjamin G.

With the advent of the internet-of-things, sensors that are constantly alert yet consuming near-zero power are desired. Remote sensing applications where sensor replacement is costly or hazardous would also benefit. Piezoelectric micro-electro-mechanical systems (MEMS) convert mechanical or acoustic energy into electrical signals while consuming zero power. When coupled with low-power complementary metal-oxide-semiconductor (CMOS) circuits, a near-zero power sensing system is formed. This work describes piezoelectric MEMS microphones based on aluminum nitride (AlN). The microphones operate as passive acoustic filters by placing their resonant response within bandwidths of interest. Devices are demonstrated with operational frequencies from 430 Hz to greater than 10 kHz with quality factors as large as 3,000 and open-circuit voltages exceeding 600 mV/Pa.

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TYPE Conference Poster YEAR 2017
ScopusOSTI

Materials Study of NbN and TaxN Thin Films for SNS Josephson Junctions

IEEE Transactions on Applied Superconductivity

Missert, Nancy A.; Brunke, Lyle B.; Henry, Michael D.; Wolfley, Steven L.; Howell, Stephen W.; Mudrick, John M.; Lewis, Rupert

Properties of NbN and TaxN thin films grown at ambient temperatures on SiO2/Si substrates by reactive-pulsed laser deposition and reactive magnetron sputtering (MS) as a function of N2 gas flow were investigated. Both techniques produced films with smooth surfaces, where the surface roughness did not depend on the N2 gas flow during growth. High crystalline quality, (111) oriented NbN films with Tc up to 11 K were produced by both techniques for N contents near 50%. The low temperature transport properties of the TaxN films depended upon both the N2 partial pressure used during growth and the film thickness. The root mean square surface roughness of TaxN films grown by MS increased as the film thickness decreased down to 10 nm.

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TYPE Journal Article YEAR 2017
ScopusOSTIDOI

Vacuum gap microstrip microwave resonators for 2.5-D integration in quantum computing

IEEE Transactions on Applied Superconductivity

Lewis, Rupert; Henry, Michael D.; Schroeder, Katlin S.

Vacuum gap λ/2 microwave resonators are demonstrated as a route toward higher integration in superconducting qubit circuits. The resonators are fabricated from pieces on two silicon chips bonded together with an In-Sb bond. Measurements of the devices yield resonant frequencies in good agreement with simulations. Creating low loss circuits in this geometry is also discussed.

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TYPE Journal Article YEAR 2017
ScopusOSTIDOI

Degradation of superconducting Nb/NbN films by atmospheric oxidation

IEEE Transactions on Applied Superconductivity

Henry, Michael D.; Wolfley, Steven L.; Young, Travis R.; Monson, Todd M.; Pearce, Charles J.; Lewis, Rupert; Clark, Blythe C.; Brunke, Lyle B.; Missert, Nancy A.

Niobium and niobium nitride thin films are transitioning from fundamental research toward wafer scale manufacturing with technology drivers that include superconducting circuits and electronics, optical single photon detectors, logic, and memory. Successful microfabrication requires precise control over the properties of sputtered superconducting films, including oxidation. Previous work has demonstrated the mechanism in oxidation of Nb and how film structure could have deleterious effects upon the superconducting properties. This study provides an examination of atmospheric oxidation of NbN films. By examination of the room temperature sheet resistance of NbN bulk oxidation was identified and confirmed by secondary ion mass spectrometry. As a result, Meissner magnetic measurements confirmed the bulk oxidation not observed with simple cryogenic resistivity measurements.

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TYPE Conference Poster YEAR 2017
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Isotropic plasma etching of Ge Si and SiNx films

Journal of Vacuum Science and Technology. B, Nanotechnology and Microelectronics

Henry, Michael D.; Douglas, Erica A.

This study reports on selective isotropic dry etching of chemically vapor deposited (CVD) Ge thin film, release layers using a Shibaura chemical downstream etcher (CDE) with NF3 and Ar based plasma chemistry. Relative etch rates between Ge, Si and SiNx are described with etch rate reductions achieved by adjusting plasma chemistry with O2. Formation of oxides reducing etch rates were measured for both Ge and Si, but nitrides or oxy-nitrides created using direct injection of NO into the process chamber were measured to increase Si and SiNx etch rates while retarding Ge etching.

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TYPE Journal Article YEAR 2016
OSTIDOI
Results 51–75 of 89
Results 51–75 of 89