CMUTs with high-K atomic layer deposition dielectric material insulation layer

Xu, Toby; Tekeş, Coşkun; Degertekin, F. Levent

doi:10.1109/tuffc.2014.006481

Cited by 17 publications

(7 citation statements)

References 35 publications

(43 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The fabrication and characterization of these CMUT arrays are discussed in the literature in great detail. [23][24][25] It should be noted that the CMUT was originally fabricated for imaging applications with a center frequency of 7 MHz in water and is not optimized as a CPUT. The CMUT capacitor is wirebonded to a printed circuit board (PCB) and forms the CPUT as part of a series RLC circuit along with a 100 lH inductor and a 20 X resistor.…”

mentioning

confidence: 99%

A capacitive ultrasonic transducer based on parametric resonance

Surappa

Satır

Degertekin

2017

Applied Physics Letters

View full text Add to dashboard Cite

A capacitive ultrasonic transducer based on a parametric resonator structure is described and experimentally demonstrated. The transducer structure, which we call capacitive parametric ultrasonic transducer (CPUT), uses a parallel plate capacitor with a movable membrane as part of a degenerate parametric series RLC resonator circuit with a resonance frequency of f. When the capacitor plate is driven with an incident harmonic ultrasonic wave at the pump frequency of 2f with sufficient amplitude, the RLC circuit becomes unstable and ultrasonic energy can be efficiently converted to an electrical signal at f frequency in the RLC circuit. An important characteristic of the CPUT is that unlike other electrostatic transducers, it does not require DC bias or permanent charging to be used as a receiver. We describe the operation of the CPUT using an analytical model and numerical simulations, which shows drive amplitude dependent operation regimes including parametric resonance when a certain threshold is exceeded. We verify these predictions by experiments with a micromachined membrane based capacitor structure in immersion where ultrasonic waves incident at 4.28 MHz parametrically drive a signal with significant amplitude in the 2.14 MHz RLC circuit. With its unique features, the CPUT can be particularly advantageous for applications such as wireless power transfer for biomedical implants and acoustic sensing.

show abstract

mentioning

confidence: 99%

A capacitive ultrasonic transducer based on parametric resonance

Surappa

Satır

Degertekin

2017

Applied Physics Letters

View full text Add to dashboard Cite

show abstract

“…With non-collapsed CMUT operation, one can easily satisfy the required C >> CCMUT condition in this approach, considering that in CMUT-on-CMOS implementation the parasitic capacitance will be minimized. For instance, a breakdown voltage of 60 V can be achieved with hafnium dioxide with a typical gap/dielectric thickness of 150 nm [32]. This approach would enable fabrication of a high voltage capacitor in the CMUT layer for compact ultrasound analog front end design in imaging applications.…”

Section: Resultsmentioning

confidence: 99%

Supply-Inverted Bipolar Pulser and Tx/Rx Switch for CMUTs Above the Process Limit for High Pressure Pulse Generation

et al. 2019

Self Cite

View full text Add to dashboard Cite

A combined supply-inverted bipolar pulser and a Tx/Rx switch is proposed to drive capacitive micromachined ultrasonic transducers (CMUTs). The supply-inverted bipolar pulser adopts a bootstrap circuit combined with stacked transistors, which guarantees high voltage (HV) operation above the process limit without lowering device reliability. This circuit generates an output signal with a peak-to-peak voltage that is almost twice the supply level. It generates a bipolar pulse with only positive supply voltages. The Tx/Rx switch adopts a diode-bridge structure with the protection scheme dedicated to this proposed pulser. A proof-of-concept ASIC prototype has been implemented in 0.18-m HV CMOS/DMOS technology with 60 V devices. Measurement results show that the proposed pulser can safely generate a bipolar pulse of-34.6 to 45 V, from a single 45 V supply voltage. The Tx/Rx switch blocks the HV bipolar pulse, resulting in less than 1.6 V at the input of the receiver. Acoustic measurements are performed connecting the pulser to CMUTs with 2 pF capacitance and 8 MHz center frequency. The variation of acoustic output pressures for different pulse shapes were simulated with the large signal CMUT model and compared with the experimental results for transmit pressure optimization. A potential implementation of the methods using MEMS fabrication methods is also described. Index Terms-Pulser, capacitive micromachined ultrasound transducer (CMUT), medical ultrasound imaging, Tx/Rx switch, ASIC, large signal model. I. INTRODUCTION apacitive micromachined ultrasound transducer (CMUT) has been shown to be a viable alternative to conventional piezoelectric sensors and transducers in ultrasound diagnostic Manuscript

show abstract

“…The stress in the nitride membrane is not considered. The electrode coverage of the membranes is kept constant at 56% and the isolation material is chosen as HfO 2 (relative permittivity = 15) of a thickness so that the electric field under operation is at 75% of the breakdown field strength [45]. Initial receiver and pulse-echo analysis is carried out on arrays with varying lateral dimensions and constant fill factor, followed by analysis on arrays with constant lateral dimensions and varying fill factor.…”

Section: Discussionmentioning

confidence: 99%

Analysis and Design of High-Frequency 1-D CMUT Imaging Arrays in Noncollapsed Mode

Arkan

Degertekin

2019

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

View full text Add to dashboard Cite

High frequency ultrasound imaging arrays are important for a broad range of applications, from small animal imaging to photoacoustics. CMUT arrays are particularly attractive for these applications as low noise receiver electronics can be integrated for an overall improved performance. In this paper we present a comprehensive analysis of high frequency CMUT arrays based on an experimentally verified CMUT array simulation tool. The results obtained on an example, a 40 MHz 1-D CMUT array for intravascular imaging, are used to obtain key design insights and tradeoffs for receive only and pulse-echo imaging. For the receiver side, thermal mechanical current noise, plane wave pressure sensitivity, and pressure noise spectrum are extracted from simulations. Using these parameters, we find that the receiver performance of CMUT arrays can be close to an ideal piston, independent of gap thickness and applied DC bias, when coupled to low noise electronics with arrays utilizing smaller membranes performing better. For pulse-echo imaging, thermal mechanical current noise limited SNR is observed to be dependent on the maximum available voltage and gap thickness. In terms of bandwidth, we find that Bragg resonance of the array, related to the fill factor, is a significant determinant of the high frequency limit and the fluid loaded single membrane resonance determines the lower limit. Based on these results, we present design guidelines requiring only fluid loaded single membrane simulations and membrane pitch to achieve a desired pulse-echo response. We also provide a design example and discuss limitations of the approach.

show abstract

CMUTs with high-K atomic layer deposition dielectric material insulation layer

Cited by 17 publications

References 35 publications

A capacitive ultrasonic transducer based on parametric resonance

A capacitive ultrasonic transducer based on parametric resonance

Supply-Inverted Bipolar Pulser and Tx/Rx Switch for CMUTs Above the Process Limit for High Pressure Pulse Generation

Analysis and Design of High-Frequency 1-D CMUT Imaging Arrays in Noncollapsed Mode

Contact Info

Product

Resources

About