High-Quality Dry Etching of LiNbO3 Assisted by Proton Substitution through H2-Plasma Surface Treatment

A wide bandgap, an enhanced piezoelectric coefficient, and low dielectric permittivity are some of the outstanding properties that have made ScxAl1−xN a promising material in numerous MEMS and optoelectronics applications. One of the substantial challenges of fabricating ScxAl1−xN devices is its difficulty in etching, specifically with higher scandium concentration. In this work, we have developed an experimental approach with high temperature annealing followed by a wet etching process using tetramethyl ammonium hydroxide (TMAH), which maintains etching uniformity across various Sc compositions. The experimental results of etching approximately 730 nm of ScxAl1−xN (x = 0.125, 0.20, 0.40) thin films show that the etch rate decreases with increasing scandium content. Nevertheless, sidewall verticality of 85°~90° (±0.2°) was maintained for all Sc compositions. Based on these experimental outcomes, it is anticipated that this etching procedure will be advantageous in the fabrication of acoustic, photonic, and piezoelectric devices.

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“…Before the

deposition, the samples were cleaned with acetone, isopropyl alcohol (IPA), and diluted (DI) water. Though piranha solution (mixture of

) can be used as an alternative cleaning approach [ 32 , 33 , 34 ], it was found in our experiments that piranha also etches the

film. After cleaning, samples were dried up with a nitrogen gun.…”

Section: Methodsmentioning

confidence: 99%

Vertical Etching of Scandium Aluminum Nitride Thin Films Using TMAH Solution

et al. 2023

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“…Lamb Wave or plate mode MEMS resonators were fabricated on 2 µm thin Y-cut LiNbO3 film suspended on Si substrate. Previously, we have reported a high-quality etching profile (smooth and re-deposition free sidewall, 94.8° verticality) for bulk and thin film LN material on several crystallographic orientations [16]. The complete fabrication process is described in reference [16].…”

Section: Design and Fabrication Of Lamb Wave Resonatormentioning

confidence: 99%

“…Previously, we have reported a high-quality etching profile (smooth and re-deposition free sidewall, 94.8° verticality) for bulk and thin film LN material on several crystallographic orientations [16]. The complete fabrication process is described in reference [16]. We implemented the same method for the device fabrication up until the dry etch processes.…”

Section: Design and Fabrication Of Lamb Wave Resonatormentioning

confidence: 99%

Realization of high-Q Lamb wave resonator with smooth vertical etching profile for thin film lithium niobate

Aryal¹,

Chityala²,

Stricklin³

et al. 2023

Novel Patterning Technologies 2023

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In this work, Lamb Wave Resonators (LWRs) based on 2 μm thin Y-cut LiNbO3 films have been fabricated using integrated fabrication process that defines IDTs (Inter Digital Transducers) on top surface and a partial Si cavity for a sacrificial layer on the bottom surface. We discuss the etch quality and its effects on the device's performance. For the first time, we present an optimized high-quality etched MEMS (Micro-electromechanical Systems) Resonator with smooth and vertical sidewalls on this material system, reporting the maximum Q-factor of 2500 at 846 MHz frequency. We observed that the resonator system has a Q-factor of 480 over the same frequency range when the etched surface has significant roughness and non-verticality. Q values of the device are greatly diminished by the presence of surface roughness and non-verticality of the etched edges. This truly highlights how important it is to have a high-quality etch profile for a piezoelectric material system like this so that the designed resonators can perform at their best.

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“…Consequently, the fabrication of MEMS based on thick lithium niobate films and SiO 2 /Si substrate is still challenging and requires development of specific deep dry etching methods. For instance, Aryal et al used proton exchanged LiNbO 3 to prevent LiF formation and its redeposition [17].…”

Section: Introductionmentioning

confidence: 99%

Microfabrication of piezoelectric MEMS based on thick LiNbO₃ single-crystal films

Ouhabaz,

Belharet,

Micard

et al. 2024

Nanotechnology

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Microfabrication procedure of piezoelectric micro electro-mechanical systems based on 5 µm thick LiNbO3 films on SiO2/Si substrate at wafer scale including deep dry etching of thick LiNbO3 films by implementing pulsed mode of Ar/SF6 gas was developed. In particular, two (YXlt)/128°/90°LiNbO3-Si cantilevers with tip mass were fabricated and characterized in terms of resonance frequency (511 Hz and 817 Hz), actuation and acceleration sensing capabilities. The quality factor of 89.5 and the electromechanical coupling of 4.8 % were estimated from measured frequency dependency of electrical impedance, fitted by using BVD model. The fabricated piezoelectric MEMS have demonstrated highly linear displacement with good sensitivity (5.28±0.02 µm/V) as a function of applied voltage and high sensitivity to vibrations of 667 mV/g indicating a suitability of the structure for actuation purposes and for acceleration or frequency sensing with high precision, respectively.

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High-Quality Dry Etching of LiNbO3 Assisted by Proton Substitution through H2-Plasma Surface Treatment

Cited by 17 publications

References 39 publications

Vertical Etching of Scandium Aluminum Nitride Thin Films Using TMAH Solution

Vertical Etching of Scandium Aluminum Nitride Thin Films Using TMAH Solution

Realization of high-Q Lamb wave resonator with smooth vertical etching profile for thin film lithium niobate

Microfabrication of piezoelectric MEMS based on thick LiNbO₃ single-crystal films

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High-Quality Dry Etching of LiNbO3 Assisted by Proton Substitution through H2-Plasma Surface Treatment

Cited by 17 publications

References 39 publications

Vertical Etching of Scandium Aluminum Nitride Thin Films Using TMAH Solution

Vertical Etching of Scandium Aluminum Nitride Thin Films Using TMAH Solution

Realization of high-Q Lamb wave resonator with smooth vertical etching profile for thin film lithium niobate

Microfabrication of piezoelectric MEMS based on thick LiNbO3 single-crystal films

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Microfabrication of piezoelectric MEMS based on thick LiNbO₃ single-crystal films