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Since semiconductor fabrication processes require numerous steps, cost and yield are critical concerns. In-situ monitoring is therefore vital for process control. However, this goal is currently restricted by the shortage of available sensors capable of performing in this manner. The goal of this research therefore, was to investigate the use of acoustic signals for monitoring and control of semiconductor fabrication equipment and processes. Currently, most methods for process monitoring (such as optical emission or interferometric techniques) rely on "looking" at a process to monitor its status. What was investigated here involved "listening" to the process. Using acoustic methods for process monitoring enhances the amount and sensitivity of data collection to facilitate process diagnostics and control. A silicon acoustic sensor was designed, fabricated, and implemented as a process monitor. Silicon acoustic sensors are favorable because of their utilization of integrated circuit and micromachining processing techniques; thus, enabling miniature devices with precise dimensions, batch fabrication of sensors, good reproducibility, and low costs. The fabricated sensor was used for in-situ monitoring of nickel-iron electrochemical deposition processes. During this process, changes occur in its plating bath as the alloy is being deposited. It is known that changes in the process medium affect the acoustic response. Thus, the sensor was implemented in an electroplating set-up and its response was observed during depositions. By mapping the sensor response received to the film thickness measured at certain times, a predictive model of the plated alloy thickness was derived as a function of sensor output and plating time. Such a model can lead to real-time monitoring of nickel-iron thickness.

Along with knowledge of the interactions unique to microscale devices, designers of microelectromechanical systems (MEMS) require information about complex fabrication and packaging techniques in order to fully complete a successful design. To that end, the successful design of MEMS requires the collaboration of experts and designers in a variety of engineering fields. From the decision-based design perspective, MEMS designers require a means to sort the input and information generated in a collaborative design process. While the potential for the use of languages and part libraries have been addressed in the literature as a means to solve this problem, a means to embody these principles has not been addressed. The use of modular, executable, decision-centric templates to rapidly compose, solve, archive, and reuse compromise Decision Support Problems (cDSP) for specific design problems has been proposed in the literature. The result of this work is a means of separating procedural design knowledge from declarative knowledge and parsing the cDSP into a set of computer-interpretable templates. A stated need in this work is the extension of the templates to accommodate the coupled solution of two cDSPs utilizing game theoretic principles. In this thesis, the theoretical structures of decision-centric templates are applied to the needs of MEMS designers. Computer interpretable, decision-centric templates, used to save, reuse, and aid in design decisions, are extended to permit MEMS designers and fabricators to collaborate via coupled cDSPs, using game theoretic principles of cooperative, noncooperative, and leader-follower games. This approach is illustrated through its application to the design and prototype fabrication of microscale gas chromatography separation channels. The outcome of this work is twofold: first, MEMS designers and fabricators will have a means to compose, collaboratively solve, archive, and reuse compromise Decision Support Problems in a computer interpretable manner, and second, decision templates will be extended through the use of game theoretic principles.

Several fabrication techniques for surface micromachined 3-D structures have been developed for RF components. The fabrication techniques all have in common the use of epoxy patterning and subsequent metallization. Techniques and structures such as embedded conductors, epoxy-core conductors, a reverse-side exposure technique, a multi-exposure scheme, and inclined patterning are presented. The epoxy-core conductor technique makes it easy to fabricate high-aspect-ratio (10-20:1), tall (~1mm) RF subelements as well as potentially very complex structures by taking advantage of advanced epoxy processes. To demonstrate feasibility and usefulness of the developed fabrication techniques for RF applications, two test vehicles are employed. One is a solenoid type RF inductor, and the other is a millimeter wave radiating structure such as a W-band quarter-wavelength monopole antenna. The embedded inductor approach provides mechanical robustness and package compatibility as well as good electrical performance. An inductor with a peak Q-factor of 21 and an inductance of 2.6nH at 4.5GHz has been fabricated on a silicon substrate. In addition, successful integration with a CMOS power amplifier has been demonstrated. A high-aspect-ratio inductor fabricated using epoxy core conductors shows a maximum Q-factor of 84 and an inductance of 1.17nH at 2.6GHz on a glass substrate with a height of 900um and a single turn. Successful W-band monopole antenna fabrication is demonstrated. A monopole with a height of 800um shows its radiating resonance at 85GHz with a return loss of 16dB. In addition to the epoxy-based devices, an advanced tunable ferroelectric device architecture is introduced. This architecture enables a low-loss conductor device; a reduced intermodulation distortion (IMD) device; and a compact tunable LC module. A single-finger capacitor having a low-loss conductor with an electrode gap of 1.2um and an electrode thickness of 2.2um has been fabricated using a reverse-side exposure technique, showing a tunability of 33% at 10V. It shows an improved Q-factor of 21.5. Reduced IMD capacitors consist of wide RF gaps and narrowly spaced high resistivity electrodes with a gap of 2um and a width of 2um within the wide gap. A 14um gap and a 20um gap capacitor show improved IMD performance compared to a 4um gap capacitor by 6dB and 15dB, respectively, while the tunability is approximately 21% at 30V for all three devices due to the narrowly spaced multi-pair high resistivity DC electrodes within the gap. Finally, a compact tunable LC module is implemented by forming the narrow gap capacitor in an inductor shape. The resonance frequency of this device is variable as a function of DC bias and a frequency tunability of 1.1%/V is achieved. The RF components developed in this thesis illustrate the usefulness of the application of micromachining technology to this application area, especially as frequencies of operation of RF systems continue to increase (and therefore wavelengths continue to shrink).

A comprehensive study of the High-pass/Low-pass topology has been performed, increasing the understanding of error sources arising from bit layout issues and fabrication tolerances. This included a detailed analysis of error sources in monolithic microwave phase shifters due to device size limitations, inductor parasitics, loading effects, and non-ideal switches. Each component utilized in the implementation of a monolithic high-low pass phase shifter was analyzed, with its influence on phase behavior shown in detail. An emphasis was placed on the net impact on absolute phase variation, which is critical to the system performance of a phased array radar system. The design of the individual phase shifter filter sections, and the influence of bit ordering on overall performance was also addressed. A variety of X-band four- and five-bit phase shifters were fabricated in a 200 GHz SiGe HBT BiCMOS technology platform, and further served to validate the analysis and design methodology. The SiGe phase shifter can be successfully incorporated into a single-chip T/R module forming a system-on-a-chip (SoC). Reduction in the physical size of transmission lines was shown to be a possibility with spinel magnetic nanoparticle films. The signal transmission properties of phase lines treated with nanoparticle thin films were examined, showing the potential for significant size reduction in both delay line and High-pass/Low-pass phase topologies. Wide-band, low-loss, and near-hermetic packaging techniques for RF MEMS devices were presented. A thermal compression bonding technique compatible with standard IC fabrication techniques was shown, that uses a low temperature thermal compression bonding method that avoids plastic deformations of the MEMS membrane. Ultimately, a system-on-a-package (SoP) approach was demonstrated that utilized packaged RF MEMS switches to maintain the performance of the SiGe phase shifter with much lower loss. The extremely competitive performance of the MEMS-based High-pass/Low-pass phase shifter, despite the lack of the extensive toolkits and commercial fabrication facilities employed with the active-based SiGe phase shifters, confirms both the effectiveness of the detailed phase error analysis presented in this work and the robust nature of the High-pass/Low-pass topology.

Microvalves are essential components of the miniaturization of the fluidic systems to control of fluid flow in a variety of applications as diverse as chemical analysis systems, micro-fuel cells, and integrated fluidic channel arrangements for electronic cooling. Using microvalves, these systems offer important advantages: they can operate using small sample volumes and provide rapid response time. This PhD dissertation presents the world first electromagnetically actuated microvalve fabricated on a single wafer with CMOS compatibility. In this dissertation, the design, fabrication, and testing results of two different types of electromagnetic microvalves are presented: the on/off microvalve and the bistable microvalve with latching mechanism. The microvalves operate with power consumption of less than 1.5 W and can control the volume flow rate of DI water, or a 50% diluted methanol solution in the range 1 - 50 µL in. The leaking rate of the on/off microvalve is the order of 30 nL/min. The microvalve demonstrated a response time for latching of 10 ms in water and 0.2 ms in air. This work has resulted in a US patent, application no. 10/699,210.Other inventions that have been developed as a result of this research are bidirectional, and bistable-bidirectional microactuators with latching mechanism, that can be utilized for optical switch, RF relay, micro mirror, nano indenter, or nano printings.

This dissertation presents the design and development of a mixed-signal low noise second-order integrated circuit (IC) for the open-loop and closed-loop operation of integrated capacitive micro- and nano-gravity accelerometers. The micromechanical accelerometers are fabricated in thick (less than 100 m) silicon-on-insulator (SOI) substrates. The IC provides the 1-bit digital output stream and has the versatility of interfacing sensors with different sensitivities while maintaining minimum power consumption (less than 5 mW) and maximum dynamic range (90 dB). A fully-differential sampled-data scheme is deployed with the ability of low-frequency noise reduction through the use of correlated double sampling (CDS) scheme. In this work, the measured resolution of the closed-loop CMOS-SOI accelerometer system, in the presence of high background accelerations, is in the micro-g (g: gravity) range. In this design, a second-order SC modulator is cascaded with the accelerometer and the front-end amplifier. The accelerometer operates in air and is designed for non-peaking response with a BW-3dB of 500 Hz. A 22 dB improvement in noise and hence dynamic range is achieved with a sampling clock of 40 kHz corresponding to a low oversampling ratio (OSR) of 40. The interface IC consumed a current of 1.5 mA from a supply of 3 V.