Nipun Sinha

Piezoelectric aluminum nitride nanoelectromechanical actuators

This letter reports the implementation of ultrathin (100 nm) aluminum nitride (AlN) piezoelectric layers for the fabrication of vertically deflecting nanoactuators. The films exhibit an average piezoelectric coefficient (d31∼−1.9 pC/N), which is comparable to its microscale counterpart. This allows vertical deflections as large as 40 nm from 18 μm long and 350 nm thick multilayer cantilever bimorph beams with 2 V actuation. Furthermore, in-plane stress and stress gradients have been simultaneously controlled. The films exhibit leakage currents lower than 2 nA/cm2 at 1 V, and have an average relative dielectric constant of approximately 9.2 (as in thicker films). These material characteristics and actuation results make the AlN nanofilms ideal candidates for the realization of nanoelectromechanical switches for low power logic applications.

Dual-beam actuation of piezoelectric AlN RF MEMS switches monolithically integrated with AlN contour-mode resonators

This work reports on piezoelectric aluminum nitride (AlN) based dual-beam RF MEMS switches that have been monolithically integrated with AlN contour-mode resonators. The dual-beam switch design presented in this paper intrinsically compensates for the residual stress in the deposited films, requires a low actuation voltage (5 to 20 V) and facilitates active pull-off to open the switch and exhibits fast switching times (1 to 2 µs). This work also presents the combined response (cascaded S parameters) of a resonator and a switch that were co-fabricated on the same substrate. The response shows that the resonator can be effectively turned on and off by the switch. A post-CMOS compatible process was used for the co-fabrication of both the switches and the resonators. The single-chip RF solution presented constitutes an unprecedented step forward towards the realization of compact, low-loss and integrated multi-frequency RF front-ends.

Multifrequency Pierce Oscillators Based on Piezoelectric AlN Contour-Mode MEMS Technology

This paper reports on the first demonstration of multifrequency (176-, 222-, 307-, and 482-MHz) oscillators based on the piezoelectric AlN contour-mode microelectromechanical systems technology. All the oscillators show phase noise values between -88 and -68 dBc/Hz at 1-kHz offset frequency from the carriers and phase noise floor values as low as -160 dBc/Hz at 1 MHz offset. The same Pierce circuit design is employed to sustain oscillations at the four different frequencies; on the other hand, the oscillator core consumes 10 mW. The AlN resonators are currently wire bonded to the integrated circuit realized in the AMIS 0.5-¿m 5-V complimentary metal-oxide-semiconductor process. Limits on phase noise and power consumption are discussed and compared with other competing technologies. This paper constitutes a substantial step forward toward the demonstration of a single-chip multifrequency reconfigurable timing solution that can be used in wireless communications and sensing applications.

Body-Biased Complementary Logic Implemented Using AlN Piezoelectric MEMS Switches

This paper reports on the implementation of low-voltage complementary mechanical logic achieved by using body-biased aluminum nitride (AlN) piezoelectric microelectro-mechanical systems (MEMS) switches. By biasing the equivalent body of a four terminal mechanical switch with a fixed voltage, the threshold voltage of the mechanical transistor has been precisely tuned and the voltage swing used for implementing digital functionalities reduced to very low values (≤ ±2 V). Thanks to the use of a mechanical switching mechanism, the AlN MEMS switches have exhibited an extremely low subthreshold slope (0.065 mV/dec), which sets the promise for even further reduction of the voltage swing to less than 100 mV. By using opposite body biases, the same mechanical switch has been made to operate as an equivalent n-like or p-like (complementary) device. Two basic AlN mechanical switch elements have then been used to form a body-biased inverter operating at 100 Hz with a ±1.5-V voltage swing. Furthermore, low voltage and functionally complete logic elements (NAND and NOR) implemented by using body-biased complementary and thin-film (250 nm thick) AlN-based piezoelectric mechanical switches have been synthesized. Finally, scaling rules for these devices are derived, and the key challenges that will need to be addressed to achieve further miniaturization are presented.

12E-3 Channel-Select RF MEMS Filters Based on Self-Coupled AlN Contour-Mode Piezoelectric Resonators

This paper reports experimental results on a new class of single-chip multi-frequency channel-select filters based on self-coupled aluminum nitride (AlN) contour-mode piezoelectric resonators. For the first time, two-port AlN contour- mode resonators are connected in series and electrically coupled using their intrinsic capacitance to form multi-frequency (94 -271 MHz), narrow bandwidth (~ .3%), low insertion loss (~4 dB), high off-band rejection (~60 dB) and extremely linear (IIP3-110 dBm) channel-select filters. This novel technology enables multi-frequency, high-performance and small form factor filter arrays and makes a single-chip multi-band RF solution possible in the near future.

Multi-frequency pierce oscillators based on piezoelectric AlN contour-mode MEMS resonators

This paper reports on the first demonstration of multi-frequency (176, 222, 307, and 482 MHz) oscillators based on piezoelectric AlN contour-mode MEMS resonators. All the oscillators show phase noise values between -88 and -68 dBc/Hz at 1 kHz offset and phase noise floors as low as -160 dBc/Hz at 1 MHz offset. The same Pierce circuit design is employed to sustain oscillations at the 4 different frequencies, while the oscillator core consumes at most 10 mW. The AlN resonators are currently wirebonded to the integrated circuit realized in the AMIS 0.5 mum 5 V CMOS process. This work constitutes a substantial step forward towards the demonstration of a single-chip multi-frequency reconfigurable timing solution that could be used in wireless communications and sensing applications.

Gravimetric chemical sensor based on the direct integration of SWNTS on ALN Contour-Mode MEMS resonators

This paper reports on the first demonstration of a gravimetric chemical sensor based on direct integration of single wall carbon nanotubes (SWNTs) grown by chemical vapor deposition (CVD) on AIN contour-mode MicroElectroMechanical (MEMS) resonators. In this first prototype the ability of SWNTs to readily adsorb volatile organic chemicals has been combined with the capability of AIN Contour-Mode MEMS resonator to provide for different levels of sensitivity due to separate frequencies of operation on the same die. Two devices with resonance frequencies of 287 MHz and 442 MHz have been exposed to different concentrations of DMMP in the range from 80 to 800 ppm. Values of mass sensitivity equal to 1.8 KHz/pg and 2.65 KHz/pg respectively have been measured.

Demonstration of low voltage and functionally complete logic operations using body-biased complementary and ultra-thin ALN piezoelectric mechanical switches

This paper reports, for the first time, on the demonstration of low voltage and functionally complete logic elements (NAND and NOR) implemented by using body-biased complementary and ultra-thin (250 nm thick) Aluminum Nitride (AlN) based piezoelectric mechanical switches. This work presents, firstly, the importance of scaling AlN films for the demonstration of ultra-thin AlN switches and, secondly, the implementation of a new actuation scheme based on body biasing to lower the switch threshold voltage. Four of these ultra-thin switches were connected together to synthesize functionally complete MEMS logic gates (NAND and NOR) with a ± 2V swing and a body-bias voltage ≪ 8 V.

Body-biased complementary logic implemented using AlN piezoelectric MEMS switches

This paper reports on the first implementation of low voltage complementary logic (≪ 1.5 V) by using body-biased aluminum nitride (AlN) piezoelectric MEMS switches. For the first time, by using opposite body biases the same mechanical switch has been made to operate as both an n-type and p-type (complementary) device. Body-biasing also gives the ability to precisely tune the threshold voltage of a switch. The AlN MEMS switches have shown extremely small subthreshold slopes and threshold voltages as low as 0.8 mV/dec and 30 mV, respectively. Furthermore, this work presents a fully mechanical body-biased inverter formed by two AlN MEMS switches operating at 100 Hz with a ± 1.5 V voltage swing.

1 Volt digital logic circuits realized by stress-resilient ALN parallel dual-beam MEMS relays

This paper reports on the first implementation of low-voltage (~ 1 Vpp) complementary logic elements achieved by body-biasing of novel parallel dual-beam design piezoelectric mechanical relays. By leveraging the mechanical actuation and the nature of these switches we have been able to develop and demonstrate a 2-to-1 multiplexer (mux) based logic design architecture that results in reduced component counts. Low-voltage (1 Vpp), lithographically integrated logic elements such as XOR, OR, AND, Half-Adder, Latch, and a 2-Stage Inverter have been synthesized by using the mux as a building block. This constitutes a step forward in the development of a low energy mechanical computing platform.