Low temperature CMUT fabrication process with dielectric lift-off membrane support for improved reliability

Pirouz, Amirabbas; Degertekin, F. Levent

doi:10.1088/1361-6439/aabe0c

Cited by 11 publications

(7 citation statements)

References 29 publications

(47 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Therefore, in order to qualitatively validate the ECR approach, it is considered that the mechanical energy output for a CMUT is proportional to the acoustic intensity, which can be measured through pressure in the far field [ 20 ]. For this purpose, a 4 membrane CMUT element is fabricated [ 21 ] as part of an array using the parameters of Table 2 as shown in Figure 11 . Then, pressure measurements in a water tank are performed and compared with model predictions for both AC only and DC biased operation.…”

Section: Experimental Validation Of Mechanical Energy Outputmentioning

confidence: 99%

An Analysis Method for Capacitive Micromachined Ultrasound Transducer (CMUT) Energy Conversion during Large Signal Operation

Pirouz

Degertekin

2019

Sensors

Self Cite

View full text Add to dashboard Cite

With Capacitive Micromachined Ultrasound Transducers (CMUTs) increasingly being used for high intensity, large signal ultrasound applications and several drive methods being proposed, the efficiency of these devices in this operation regime have not been quantitatively evaluated. Since well-known frequency and capacitance-based coupling coefficients definitions are not valid for large signal, nonlinear operation, an energy-based definition should be used. In this paper, an expression for mechanical energy in a CMUT is obtained based on the assumption that CMUT is a linear time varying capacitor in all regimes of operation. This expression is evaluated by the help of an experimentally verified nonlinear CMUT model to define an energy conversion ratio (ECR) which can be considered as a coupling coefficient valid for all regimes of operation. This parameter is validated in the small signal regime and then used to evaluate CMUT performance with various large drive signals. The quantitative modeling results show that CMUTs do not need DC bias to achieve high efficiency large signal transduction: AC only signals at half the operation frequency with amplitudes beyond the collapse voltage can provide efficiencies (ECR) above 0.9 with harmonic content below −25 dB. Based on these results, ECR variation with membrane geometry and parasitic capacitance are given as examples for device optimization. The overall modeling approach is also qualitatively validated by experiments.

show abstract

Section: Experimental Validation Of Mechanical Energy Outputmentioning

confidence: 99%

An Analysis Method for Capacitive Micromachined Ultrasound Transducer (CMUT) Energy Conversion during Large Signal Operation

Pirouz

Degertekin

2019

Sensors

Self Cite

View full text Add to dashboard Cite

show abstract

“…The CMUT arrays are fabricated using low-temperature CMUT-on-CMOS process [2], [13]. The arrays are processed on the CMOS substrate which is passivated with 3 m of Plasma-enhanced chemical vapor deposition (PECVD) silicon nitride (SiN).…”

Section: Cmut Design and Fabricationmentioning

confidence: 99%

Single-Chip Reduced-Wire CMUT-on-CMOS System for Intracardiac Echocardiography

Jung

Pirouz

Tekeş

et al. 2018

2018 IEEE International Ultrasonics Symposium (IUS)

Self Cite

View full text Add to dashboard Cite

CMUT-on-CMOS integration is particularly suitable for catheter based ultrasound imaging applications, where electronics integration enables multiplexing capabilities to reduce the number of electrical connections leading to smaller catheter cable profiles. Here, a single-chip CMUT-on-CMOS system for intracardiac echocardiography (ICE) is presented. In this system, a 64 element 1-D CMUT array is fabricated over an application specific integrated circuit (ASIC) that features a programmable transmit beamformer with high voltage (HV) pulsers and receive circuits using 8:1 time division multiplexing (TDM). Integration of pitch matched 64 channel front-end circuits with CMUT arrays in a single-chip configuration allows for implementation of catheter probes with miniaturization, reduced number of cables, and better mechanical flexibility. The ASIC is implemented in 60 V 0.18 µm HV process. It occupies 2.6×11 mm 2 which can fit in the catheter size of 9F, and reduces the number of wires from more than 64 to 22. This system is used for B-mode imaging of imaging phantoms and its potential application for 2D CMUT-on-CMOS arrays is discussed. Keywords-Capacitive micromachined ultrasound transducer (CMUT), medical ultrasound imaging, intracardiac echocardiography (ICE), CMUT-on-CMOS.

show abstract

“…Many solutions to dielectric charging have been suggested, including optimization of film surface roughness [19] and quality [20], investigation of different dielectrics [15], [21], and architectural adjustments such as isolation posts [8], [22], [23]. However, optimization of films alone does not fully eliminate charging.…”

Section: Introductionmentioning

confidence: 99%

High-Performance Electrode-Post CMUTs: Fabrication Details and Best Practices

Dew

Zemp

2023

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

View full text Add to dashboard Cite

Capacitive micromachined ultrasound transducers (CMUTs) have been investigated for over 25 years due to their promise for mass manufacturing and electronic co-integration. Previously, CMUTs were fabricated with many small membranes comprising a single transducer element. This, however, resulted in sub-optimal electromechanical efficiency and transmit performance, such that resulting devices were not necessarily competitive with piezoelectric transducers. Moreover, many previous CMUT devices were subject to dielectric charging and operational hysteresis that limited long-term reliability. Recently we demonstrated a CMUT architecture using a single long rectangular membrane per transducer element and novel electrode post structures. This architecture not only offers long-term reliability, but also provides performance advantages over previously published CMUT and piezoelectric arrays. The purpose of this paper is to highlight these performance advantages and provide details of the fabrication process, including the best practices to avoid common pitfalls. The objective is to provide sufficient detail to inspire a new generation of microfabricated transducers which could lead to performance gains of future ultrasound systems.

show abstract

Low temperature CMUT fabrication process with dielectric lift-off membrane support for improved reliability

Cited by 11 publications

References 29 publications

An Analysis Method for Capacitive Micromachined Ultrasound Transducer (CMUT) Energy Conversion during Large Signal Operation

An Analysis Method for Capacitive Micromachined Ultrasound Transducer (CMUT) Energy Conversion during Large Signal Operation

Single-Chip Reduced-Wire CMUT-on-CMOS System for Intracardiac Echocardiography

High-Performance Electrode-Post CMUTs: Fabrication Details and Best Practices

Contact Info

Product

Resources

About