BCB polymer based row-column addressed CMUT

Havreland, Andreas Spandet; Ommen, Martin Lind; Silvestre, Chantal; Engholm, Mathias; Jensen, Jørgen Arendt; Thomsen, Erik Vilain

doi:10.1109/ultsym.2017.8092524

Cited by 3 publications

(12 citation statements)

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“…The derived pull-in models have been compared with both FEM simulations and experiential data [32]- [34]. The accuracy of the models are investigated using FEM simulation and thus under a fully controlled environment.…”

Section: Resultsmentioning

confidence: 99%

“…Two sets of CMUT parameters have been used. The first set of parameters is denoted simulation A, and these parameters are similar to the design parameter used for the three evaluated CMUTs in [32]- [34]. The parameters used for the second simulation, B, are chosen such that the deflection of the plate is small compared to the plate thickness, or in other words in the linear elastic regime.…”

Section: Resultsmentioning

confidence: 99%

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Analytical Deflection Profiles and Pull-In Voltage Calculations of Prestressed Electrostatic Actuated MEMS Structures

Havreland

Thomsen

2021

J. Microelectromech. Syst.

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This paper presents a zeroth and first order perturbative analysis of prestressed electrostatic actuated Microelectromechanical systems (MEMS). Perturbation theory is used to calculate the deflection profile of various MEMS structures, from which the pull-in voltage is estimated using the weighed residual method, where both a Galerkin expression and a Dirac delta function have been used as weight functions. A prestressed circular Capacitative Micromachined Ultrasonic Transducer (CMUT) is used as the main example in this paper. This device is modeled as a circular clamped plate subjected to an electrostatic pressure. The calculated pull-in voltage has been compared with experimental data of highly prestressed CMUTs, where a relative error between −36% and −8% is observed for a model that does not include stress. The model that includes the residual stress lowers the range of the relative error to values between −5% and 21%. To improve the accuracy of the pull-in voltage estimate Richardson extrapolation has been calculated from the zeroth and first order estimates. The pull-in voltage models are compared with a Finite Element Model (FEM), where an overestimation, in the high stress regime, of 10% is observed for the zeroth order model, less than 5% for the Galerkin method and 3% for the Richardson extrapolation.[2020-0358]

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Analytical Deflection Profiles and Pull-In Voltage Calculations of Prestressed Electrostatic Actuated MEMS Structures

Havreland

Thomsen

2021

J. Microelectromech. Syst.

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“…Adhesive bonding is another route to low-temperature wafer bonding [27,28]. A polymer adhesive is used as the intermediate layer for bonding the wafers together.…”

Section: Introductionmentioning

confidence: 99%

“…Another advantage associated with the polymers is that they have very high surface energy and, due to the low-temperature process, they result in low bonding stresses. So far, benzocyclobutene (BCB) and SU-8 polymers have been successfully used as an adhesive layer for CMUT fabrication [22,24,28,29]. Among all adopted methods, the lowest temperature reported in the literature for CMUT fabrication was about 250∘normalC.…”

Section: Introductionmentioning

confidence: 99%

“…Therefore, in the presented CMUT, the entire thickness of the wafer was on purpose used as the membrane. Lower membrane thickness can also be achieved by either using a thinner wafer or by using the silicon nitride wafers and adopting the steps presented in References [22,28] for achieving a thinner membrane. With the silicon nitride wafers, a nanometer-level nitride membrane can be achieved at the additional cost of silicon-etching and electrode-deposition steps.…”

Section: Introductionmentioning

confidence: 99%

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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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A Hand-Held 190+190 Row–Column Addressed CMUT Probe for Volumetric Imaging

Grass

Engholm

Havreland

et al. 2022

IEEE Open J. Ultrason., Ferroelect., Freq. Contr.

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This paper presents the design, fabrication, and characterization of a 190+190 row-column addressed (RCA) capacitive micromachined ultrasonic transducer (CMUT) array integrated in a custom hand-held probe handle. The array has a designed 4.5 MHz center frequency in immersion and a pitch of 95 µm which corresponds to ≈ λ/4. The array has a 2.14 × 2.14 cm 2 footprint including an integrated apodization scheme to reduce ghost echoes when performing ultrasound imaging. The array was fabricated using a combination of fusion and anodic bonding, and a deposit, remove, etch, multistep (DREM) etch to reduce substrate coupling and improve electrode conductivity. The transducer array was wire-bonded to a rigid-flex printed circuit board (PCB), encapsulated in room temperature vulcanizing (RTV) silicone polymer, electromagnetic interference (EMI) shielded, and mounted in a 3D-milled PPSU probe handle. The probe was characterized using the SARUS experimental scanner and 3D volumetric imaging was demonstrated on scatter and wire phantoms. The imaging depth was derived from tissue mimicking phantom measurements (0.5 dB MHz −1 cm −1 attenuation) by estimating the SNR at varying depths. For a synthetic aperture imaging sequence with 96+96 emissions the imaging depth was 3.6 cm. The center frequency measured from the impulse response spectra in transmit and pulse-echo was 6.0 ± 0.9 MHz and 5.3 ± 0.4 MHz, and the corresponding relative bandwidths were 62.8 ± 4.5 % and 86.2 ± 10.4 %. The fabrication process showed clear improvement in relative receive sensitivity and transmit pressure uniformity compared to earlier silicon-on-insulator (SOI) based designs. However, at the same time it presented yield problems resulting in only around 55 % elements with a good response.

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BCB polymer based row-column addressed CMUT

Cited by 3 publications

References 0 publications

Analytical Deflection Profiles and Pull-In Voltage Calculations of Prestressed Electrostatic Actuated MEMS Structures

Analytical Deflection Profiles and Pull-In Voltage Calculations of Prestressed Electrostatic Actuated MEMS Structures

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

A Hand-Held 190+190 Row–Column Addressed CMUT Probe for Volumetric Imaging

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