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TOWARDS A CMOS INTEGRATED PIEZOELECTRIC MEMS PROCESS DESIGN KIT
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Plant parasitic nematodes are soil-borne microscopic worms that parasitize plant roots, reducing cropy ields for economically important crops such as soybeans, sugarbeets, and strawberries, to name a few. This paper presents the concept of using a GHz ultrasonic imaging array to image nematodes, as a way to quantify nematode populations within soil. A 128-pixel by 128-pixel, 1.85 GHz monolithic CMOS integrated ultrasonic imager was successfully used to image nematodes in moist soil, air, and thin layers of water
We describe an AlN-based resonant switch for use in a near zero power RF wake-up receiver. A folded beam structure with a slot compensates for the curvature caused by the stress gradient in the sputtered AlN film and ensures that the released contact gap is approximately equal to the designed contact gap. A 80 kHz resoswitch with Q of 8600 and an actuation gap of approximately 600 nm turns on when a -4 dBm, 800MHz signal, square wave modulated at 80 kHz, is applied to the actuator. This AlN electrostatic resonant switch is designed to enable integration with a high gain AlN RF piezoelectric transformer to form a complete ultra-low power RF receiver.
This paper presents a 591×438-DPI ultrasonic fingerprint sensor. The sensor is based on a piezoelectric micromachined ultrasonic transducer (PMUT) array that is bonded at wafer-level to complementary metal oxide semiconductor (CMOS) signal processing electronics to produce a pulse-echo ultrasonic imager on a chip. To meet the 500-DPI standard for consumer fingerprint sensors, the PMUT pitch was reduced by approximately a factor of two relative to an earlier design. We conducted a systematic design study of the individual PMUT and array to achieve this scaling while maintaining a high fill-factor. The resulting 110×56-PMUT array, composed of 30×43-μm2 rectangular PMUTs, achieved a 51.7% fill-factor, three times greater than that of the previous design. Together with the custom CMOS ASIC, the sensor achieves 2 mV kPa−1 sensitivity, 15 kPa pressure output, 75 μm lateral resolution, and 150 μm axial resolution in a 4.6 mm×3.2 mm image. To the best of our knowledge, we have demonstrated the first MEMS ultrasonic fingerprint sensor capable of imaging epidermis and sub-surface layer fingerprints.
A flexible, modular manufacturing process for integrating
micromechanical and microelectronic devices has been developed. This
process embeds the micromechanical devices in an anisotropically etched
trench below the surface of the wafer. Prior to microelectronic device
fabrication, this trench is refilled with oxide, chemical-mechanically
polished, and sealed with a nitride cap in order to embed the
micromechanical devices below the surface of the planarized wafer. The
feasibility of this technique in a manufacturing environment has been
demonstrated by combining a variety of embedded micromechanical
structures with a 2 μm CMOS process on 6 inch wafers. A yield of 78%
has been achieved on the first devices manufactured using this technique
We demonstrate ultralow loss AlN single-mode channel waveguide and AlN electro-optic (EO) modulators in CMOS compatible AlN-on-insulator photonic circuits. Propagation loss was measured to be ~0.42 dB/cm at 1550 nm and ~2.36 dB/cm at 905 nm. A push-pull MZI modulator with arm length of 2.8 cm exhibits Vπ of ~21 V at 1550 nm and ~12.9 V at 1064 nm, and modulation speed of ~140 MHz, limited by the resistive-capacitive delay. A dual-ring modulator exhibits extension ratio of ~12 dB and high modulation speed of ~4 GHz because of its small footprint as compared with the MZI modulator.
As CMOS electronics scale to smaller dimensions, wired interconnect density, power consumption, and delays have introduced bottlenecks in performance. Ultrasonic communication links integrated within the silicon substrate offer an opportunity to create low power high data rate channels. We have utilized ultrasonic phased arrays, micro-sonars, for reconfigurable communication links. Brand new vistas in computer architecture and low power computing are enabled by these links, including brain inspired computing. This paper demonstrates the use of phased array elements to create a reconfigurable 120 Mbit per second channel in silicon. The array is capable of selectively communicating to four different locations on chip.
Novel thin-film piezoelectric aluminum nitride rate gyroscope
- F T Goericke
- G Vigevani
- I I Izyumin
- B E Boser
- A P Pisano
F. T. Goericke, G. Vigevani, I. I. Izyumin, B. E. Boser and A.
P. Pisano, "Novel thin-film piezoelectric aluminum nitride rate
gyroscope," 2012 IEEE International Ultrasonics Symposium,
2012, pp. 1067-1070.
- X Liu
X. Liu et al., "Post-CMOS Compatible Aluminum Scandium
Nitride/2D Channel Ferroelectric Field-Effect-Transistor
Memory," Nano Letters, 2021, 21, pp. 3753-3761.
Sensitivity and resonance frequency with changing the diaphragm diameter of piezoelectric micromachined ultrasonic transducers
- Daisuke Akai
- Takeo Katori
- Daisuke Takashima
- Makoto Ishida
Daisuke Akai, Takeo Katori, Daisuke Takashima, and Makoto
Ishida, "Sensitivity and resonance frequency with changing the
diaphragm diameter of piezoelectric micromachined ultrasonic
transducers", AIP Conference Proceedings 1709, 020010
(2016).