Progresses in cMUT device fabrication using low temperature processes

Bahette, Emilie; Michaud, Jean-François; Certon, Dominique; Gross, D.; Alquier, Daniel

doi:10.1088/0960-1317/24/4/045020

Cited by 11 publications

(15 citation statements)

References 27 publications

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“…Studies indicate that there are competing oxidation reactions between formation of

\left(\text{NiO}\right)_{x}

and

\left(\text{SiO}\right)_{\text{z}}

, that might depend on the specific nickel silicide composition and doping. [ 38,39 ] The formation of nickel silicides by a Ni layer deposited on a c‐Si volume material usually occurs sequentially via the following reaction path: [ 40 ] 1) Ni is present on the c‐Si substrate at room temperature. 2) At temperature

T \left(&amp;amp;amp;amp;amp;amp;amp;amp;amp;gt; 200\right)^{\circ} \text{C}

, nickel‐rich

\left(\text{Ni}\right)_{2} \text{Si}

forms at the Ni/Si interface until all of the Ni is reacted at

T sim \left(300\right)^{\circ} \text{C}

.…”

Section: Discussionmentioning

confidence: 99%

“…Studies indicate that there are competing oxidation reactions between formation of NiO x and SiO z , that might depend on the specific nickel silicide composition and doping. [38,39] The formation of nickel silicides by a Ni layer deposited on a c-Si volume material usually occurs sequentially via the following reaction path: [40] 1) Ni is present on the c-Si substrate at room temperature. Temporarily, both silicide phases are present simultaneously.…”

Section: Ag/nio X /(Ni)/poly-si/c-si Contact Samplesmentioning

confidence: 99%

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Enhancement of NiO_x/Poly‐Si Contact Performance by Insertion of an Ultrathin Metallic Ni Interlayer

Lange

Fett

Kabaklı

et al. 2023

Physica Status Solidi (a)

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Nickel oxide (NiOx$\left(\text{NiO}\right)_{x}$) is a promising hole transport material for perovskite/Si tandem solar cells. Various silicon cell architectures may be used as bottom cells. The polycrystalline (poly‐Si) p+false/n+$\left(\text{p}\right)^{+} / \left(\text{n}\right)^{+}$ tunnel diode is expected to be a high‐efficiency interconnection scheme between the two subcells of monolithic tandems in p‐i‐n configuration with a high thermal budget, excellent passivation properties, and low contact resistivity. However, NiOx$\left(\text{NiO}\right)_{x}$ is then interfaced to poly‐Si(p+$\left(\text{p}\right)^{+}$) and the chemical integrity of the interface due to the necessity of annealing treatments has to be questioned. For this purpose, the NiOx$\left(\text{NiO}\right)_{x}$/poly‐Si contact resistivity for different annealing temperatures is investigated between 100 and 500 °C, and two different NiOx$\left(\text{NiO}\right)_{x}$ deposition techniques, namely, wet‐chemically applied and sputter‐deposited NiOx$\left(\text{NiO}\right)_{x}$. The values of more than 1 Ω cm2$1 \textrm{ } \Omega \textrm{ } \left(\text{cm}\right)^{2}$ are obtained. The insertion of a nm‐thin metallic Ni interlayer is shown to enable a tremendous decrease of the contact resistivity by 2–3 orders of magnitude. The formation of NiSi2$\left(\text{NiSi}\right)_{2}$ is proven by highly resolved (scanning) transmission electron microscopy ((S)TEM) coupled with energy‐dispersive X‐ray spectroscopy (EDXS). This interfacial engineering approach is expected to provide an effective way of improving the contact properties and integrability of NiOx$\left(\text{NiO}\right)_{x}$ into various tandem cell processes.

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“…Studies indicate that there are competing oxidation reactions between formation of

\left(\text{NiO}\right)_{x}

and

\left(\text{SiO}\right)_{\text{z}}

T \left(&amp;amp;amp;amp;amp;amp;amp;amp;amp;gt; 200\right)^{\circ} \text{C}

, nickel‐rich

\left(\text{Ni}\right)_{2} \text{Si}

forms at the Ni/Si interface until all of the Ni is reacted at

T sim \left(300\right)^{\circ} \text{C}

.…”

Section: Discussionmentioning

confidence: 99%

Section: Ag/nio X /(Ni)/poly-si/c-si Contact Samplesmentioning

confidence: 99%

Enhancement of NiO_x/Poly‐Si Contact Performance by Insertion of an Ultrathin Metallic Ni Interlayer

Lange

Fett

Kabaklı

et al. 2023

Physica Status Solidi (a)

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show abstract

“…Capacitive Micromachined Ultrasonic Transducers (CMUTs), a potential alternative for piezoelectric ultrasonic transducers, have been under extensive development since their introduction in the mid-1990s [1,2,3,4,5,6,7,8,9,10]. Initially developed for air-coupled applications, CMUTs have shown far better acceptability in immersion applications, including medical ultrasonic imaging, medical therapy, and underwater imaging [11,12,13,14,15].…”

Section: Introductionmentioning

confidence: 99%

PMMA-Based Wafer-Bonded Capacitive Micromachined Ultrasonic Transducer for Underwater Applications

2019

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This article presents a new wafer-bonding fabrication technique for Capacitive Micromachined Ultrasonic Transducers (CMUTs) using polymethyl methacrylate (PMMA). The PMMA-based single-mask and single-dry-etch step-bonding device is much simpler, and reduces process steps and cost as compared to other wafer-bonding methods and sacrificial-layer processes. A low-temperature (< 180 ∘ C ) bonding process was carried out in a purpose-built bonding tool to minimize the involvement of expensive laboratory equipment. A single-element CMUT comprising 16 cells of 2.5 mm radius and 800 nm cavity was fabricated. The center frequency of the device was set to 200 kHz for underwater communication purposes. Characterization of the device was carried out in immersion, and results were subsequently validated with data from Finite Element Analysis (FEA). Results show the feasibility of the fabricated CMUTs as receivers for underwater applications.

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“…Although the electroacoustic transducers must be miniaturized and the density must be increased for acquiring the three‐dimensional, the dicing process is not suitable to fabricate the miniaturized transducers. To overcome this problem and realize three‐dimensional imaging, research and development have been carried out on capacitive micromachined ultrasonic transducers (CMUT) fabricated with microelectromechanical systems (MEMS) technologies . The MEMS technologies can be relatively easy to fabricate the transducers with tens of micrometers and the high density patterns.…”

Section: Introductionmentioning

confidence: 99%

“…To overcome this problem and realize three-dimensional imaging, research and development have been carried out on capacitive micromachined ultrasonic transducers (CMUT) fabricated with microelectromechanical systems (MEMS) technologies. [2][3][4][5][6][7] The MEMS technologies can be relatively easy to fabricate the transducers with tens of micrometers and the high density patterns.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of capacitance changes of capacitive micromachined ultrasonic transducers for ultrasonic diagnoses by charge‐injection

Aono

Yoshimura

Machida

2018

Elect Comm in Japan

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This research reports capacitance–voltage (CV) changes of capacitive micromachined ultrasonic transducers (CMUT) for ultrasonic diagnoses. The CMUT constitutes an electrostatically vibrating film, which is fabricated by deposition processes of SiO2 and SiN films as insulator and TiN and Al films as top electrode on a Si substrate. The ultrasonic waves are transmitted by addition of AC voltage between the top electrode and the Si substrate, whereas the reflective ultrasonic wave are received with the vibrating film and converted to the electrical signals for ultrasonic diagnostic images. There is a problem that the CV changes of CMUT occur due to charge‐injection into the insulator, since a high AC and DC voltages are applied for driving the vibrating film. Thus, it is necessary to suppress the change in CV characteristics of the CMUT due to charge‐injection. It is clarified that the CV drift due to charge‐injection can be decreased by forming the top electrode so as to cover the vibrating film. Also, the CV drift is able to be suppressed by setting the driving voltage to be equal to or less than the collapse voltage.

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Progresses in cMUT device fabrication using low temperature processes

Cited by 11 publications

References 27 publications

Enhancement of NiO_x/Poly‐Si Contact Performance by Insertion of an Ultrathin Metallic Ni Interlayer

Enhancement of NiO_x/Poly‐Si Contact Performance by Insertion of an Ultrathin Metallic Ni Interlayer

PMMA-Based Wafer-Bonded Capacitive Micromachined Ultrasonic Transducer for Underwater Applications

Evaluation of capacitance changes of capacitive micromachined ultrasonic transducers for ultrasonic diagnoses by charge‐injection

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Progresses in cMUT device fabrication using low temperature processes

Cited by 11 publications

References 27 publications

Enhancement of NiOx/Poly‐Si Contact Performance by Insertion of an Ultrathin Metallic Ni Interlayer

Enhancement of NiOx/Poly‐Si Contact Performance by Insertion of an Ultrathin Metallic Ni Interlayer

PMMA-Based Wafer-Bonded Capacitive Micromachined Ultrasonic Transducer for Underwater Applications

Evaluation of capacitance changes of capacitive micromachined ultrasonic transducers for ultrasonic diagnoses by charge‐injection

Contact Info

Product

Resources

About

Enhancement of NiO_x/Poly‐Si Contact Performance by Insertion of an Ultrathin Metallic Ni Interlayer

Enhancement of NiO_x/Poly‐Si Contact Performance by Insertion of an Ultrathin Metallic Ni Interlayer