Design, fabrication, packaging and testing of thin film thermocouples for boiling studies

Boiling is the most efficient form of heat transfer. Thermo-fluidic transport mechanisms at different length and time scales govern the nature of boiling. This study was conducted to enhance the understanding of the surface temperature variations and fluctuations during boiling. Microfabricated thin film thermocouples were used in this study. The main aim of this study was to develop a repeatable procedure for fabrication of thin film thermocouples and to test them by measuring surface temperatures during various boiling regimes. Since thin film thermocouples are known to provide reliable measurements at very fast response rates, they were selected for this study. Small temperature fluctuations at high sampling rates were studied in boiling experiments conducted using PF-5060 as the boiling medium. An experimental apparatus was fabricated for conducting these experiments and it contained a viewing chamber whichblock for sensing the temperature during boiling on its surface. The small size of these thermocouples was another big advantage as they were expected to cause minimal interference to the temperature distribution and the transport phenomenon during boiling. This thesis reports the design evolution of the thermocouples according to the need of packaging and describes the fabrication process with sufficient detail so that it can be easily reproduced given the same facilities and environment. The results of testing show that they can be used for monitoring and analyzing surface temperature variations and fluctuations during various boiling regimes with better temporal resolution. housed the copper block used for providing the heat for boiling. The substrate with thin film thermocouples was placed on top of this copper block for sensing the temperature during boiling on its surface. The small size of these thermocouples was another big advantage as they were expected to cause minimal interference to the temperature distribution and the transport phenomenon during boiling. This thesis reports the design evolution of the thermocouples according to the need of packaging and describes the fabrication process with sufficient detail so that it can be easily reproduced given the same facilities and environment. The results of testing show that they can be used for monitoring and analyzing surface temperature variations and fluctuations during various boiling regimes with better temporal resolution

Novel Electrode Configurations in Dual-Layer Stacked and Switchable AlN Contour-Mode Resonators for Low Impedance Filter Termination and Reduced Insertion Loss

This paper reports, for the first time, on the design and demonstration of two novel electrode configurations in dual-layer stacked Aluminum Nitride (AlN) piezoelectric contour-mode resonators to obtain low filter termination resistance (down to 300 Ω, which also results in better filter out-of-band rejection) and reduced insertion loss (IL as low as 1.6 dB) in multi-frequency (100 MHz – 1 GHz) AlN MEMS filters. The microfabrication process is fully compatible with the previously demonstrated AlN RF MEMS switches, which makes it possible to design and integrate multi-frequency switchable filter banks on a single chip

Integration of AlN Micromechanical Contour-Mode Technology Filters with Three-Finger Dual Beam AlN MEMS Switches

In this paper, we present the first demonstration of the monolithic integration of Aluminum Nitride (AlN) micromechanical contour mode technology filters with dual-beam actuated MEMS AlN switches. This integration has lead to the development of the first prototype of a fully-integrated all-mechanical switchable filter. Integration has been demonstrated by using AlN contour-mode MEMS filters at two center frequencies, i.e. 98.7 and 279.9 MHz. The micromechanical switch design used here is a novel three-finger dual-beam topology that improves the isolation and insertion loss of the switch by decreasing the parasitic coupling between the DC and RF signals over a previous AlN MEMS dual-beam design. With the use of just one switch fabricated right next to, and integrated with the filter, the AlN MEMS filter is effectively turned off and its pass-band transmission is lowered to the out of band level at 279.9 MHz

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 \u3c 8 V

100 NM Thick Aluminum Nitrade Based Piezoelectric Nano Switches Exhibiting 1 MV Threshold Voltage via Body-Biasing

This paper reports on the first demonstration of aluminum nitride (AIN) piezoelectric logic switches that were fabricated with ultra-thin (100nm) AIN films and exhibit a 1 mV threshold voltage via the body-biasing scheme. The application of a relatively low (\u3c 6 V) fixed potential to the body terminal of a 4-terminal switch has been cycled to \u3e 109 cycles and, although the contact resistance was found to be high (~ 1 MΩ), the nano-films have functioned throughout to show high piezoelectric nano-film reliability

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 low actuation voltage (5 to 20 V), 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 herein constitutes an unprecedented step forward towards the realization of compact, low loss and integrated multi-frequency RF front-ends

Body-Biased Complementary Logic Implemented Using AIN Piezoelectric MEMS Switches

This paper reports on the first implementation of low voltage complementary logic (\u3c 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 ntype 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

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 μm 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

Channel-Select RF MEMS Filters Based On Self-Coupled A1N 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 (A1N) 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 (~0.3%), 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

Hybrid Ultra-Compact 4th Order Band-Pass Filters Based On Piezoelectric AlN Contour-Mode MEMS Resonators

This work reports on the design, fabrication and testing of a new class of hybrid (filter design using combined electrical and mechanical coupling techniques) ultra-compact (800×120 μm) 4th order band-pass filters based on piezoelectric Aluminum Nitride (AlN) contour-mode microelectromechanical (MEM) resonators. The demonstrated 110 MHz filter shows a low insertion loss of 5.2 dB in air, a high out-of-band rejection of 65 dB, a fractional bandwidth as high as 1.14% (hard to obtain when only conventional electrical coupling is used in the AlN contour-mode technology), and unprecedented 30 dB and 50 dB shape factors of 1.93 and 2.36, respectively. All these are achieved in an extremely small footprint and by using just half the space that any other 4th order filter would have taken. In terms of nonlinearities, the 110 MHz filter shows a 1 dB compression point higher than +63 dBmV and input third order intercept point (IIP3) values well beyond +153 dBmV. This new hybrid design represents a net improvement over the state of the art and constitutes a very promising solution for intermediate frequency (IF) filtering in many wireless communication systems