Wire bonding is the process of creating interconnects between the circuitry on a microchip and PCB boards or substrates so that the microchip can interact with the outside world. The materials and techniques used in this bonding process can cause a wide variation in bond quality, so wire bond reliability testing is very important in determining the quality and longevity of wire bonds. Due to the fact that microchips are encased in protective resins after bonding and their substrates attached to the larger device as a whole, once any single wire bond fails then it could jeapordize the entire device as the wire bonds cannot be individually replaced or fixed. Current methods of reliability testing are lengthy and often destroy the entire sample in the process of evaluation, so the availability of novel non-destructive, real-time monitoring methods as well as accelerated aging could reduce costs and provide realistically timed tests of novel wire bond materials which do not form Intermetallic compounds (IMCs) as rapidly as Au wire on Al substrates. In this thesis, five new chip designs for use in wire bond reliability testing are reported, focusing on the first joint made in a wire bond, called the ball bond. These chips are scaled either to test up to 55 test bonds simultaneously or just one at a time, introducing different requirements for microchip infrastructure capabilities, such as on-chip sensing/data bus, multiplexer, and switches able to operate under High Temperature Storage (HTS) which ranges from temperatures of 150-220 ??C. There are different heating requirements for each of these microchips, needing to be heated externally or containing on-chip microheaters to heat only the ball bond under test, and not the rest of the microchip or surrounding I/O pads. Of the five chip designs, sample chips were produced by an external company. Experimental studies were then carried out with two of these chip designs. They were specifically made to test novel methods of determining ball bond reliability using in-situ, non-destructive sensing, in real-time, while the ball bond undergoes thermal aging. Pad resistance as an analysis tool for ball bond reliability is proposed in this thesis as a new way of evaluating ball bond quality and allows for the testing of electrical connection without the need for specialized measurement probes or difficult bonding processes that contact resistance measurements require. Results are reported for pad resistance measurements of a ball bond under very high temperature storage (VHTS) at 250 ??C, a temperature exceeding typical HTS ranges to accelerate aging. Pad resistance measurements are taken using the four-wire measurement method from each corner of the bond pad, while reversing current direction every measurement to remove thermo-electric effects, and then calculating the average square resistance of the pad from this value. The test ball bond is aged using a novel on-chip microheater which is a N+ doped Si resistive heater located directly underneath the bond pad, and can achieve temperatures up to 300 ??C while not aging any of the I/O pads surrounding it, which are located ~180 ??m away. A 50 ??? resistor is placed 60 ??m away from the heater to monitor the temperature. The use of a microheater allows the aging of novel wire types at temperatures much higher than those permitted for microchip operation while thermally isolating the test bond from the sensing and power bonds, which do not need to be aged. Higher temperatures allow the aging process to be sped up considerably. The microheater is programmatically cycled between 250 ??C (for 45 min) and 25 ??C (for 15 min) for up to 200 h or until the pad resistance measurements fail due breakdown of the bonding pad. Intermetallic compounds forming between the ball bond and the pad first become visible after a few hours, and then the pad becomes almost completely consumed after a day. The pad resistance is measured every few seconds while the sample is at room temperature, and the increase in pad resistance agrees with the fact that Au/Al IMC products are known to have much higher resistance than both pure Au or Al. Also discussed are some aging results of Au wires and Pd coated Cu (PCC) wires bonded to Al bonding pads and aged at a temperature of 200 ??C in an oven for 670 h. The oven aged Au ball bonds also saw IMC formation on the surface of the bonding pad, much like the microheater tests. The PCC ball bonds became heavily oxidized due to lack of Pd on the surface of the ball, the wire portions did not oxidize much. In conclusion, the new structures have been demonstrated to age ball bonds faster than with conventional methods while obtaining non-destructive data. Specifically, the new microheater ages a test bond at an accelerated rate without having an observable effect on the I/O connections used to monitor the test bond. Pad resistance measurements correlate to the aging of the test bond and ensure the electrical integrity of the joint is checked.

With the proliferation of industries world-wide, there is a growing need and interest in sensing and monitoring environmental pollutants and monitoring the concentration of chemicals/gases in industrial process control. There is also an increasing demand for chemical sensors in other applications such as home security, breath analysis and food processing. Design and development of metal-oxide based gas sensor system is reported in this thesis. The system consists of three components viz. micro heater(which aids inheating the sensor film to required temperatures), CMOS ASIC (the sensor interface circuit) and the thin film transducer(a semiconducting metal oxide thin film whose resistance changes with the concentration of the target gas). Microheaters were realized through PolyMUMPs process. Thermal characterization of surface-micromachined microheaters is carried out from their dynamic response to electrothermal excitations. An electrical equivalent circuit model is developed for the thermo-mechanical system. The mechanical parameters are extracted from the frequency response obtained using a Laser Doppler Vibrometer. The resonant frequencies of the microheaters are measured and compared with FEM simulations. The thermal time constants are obtained from the electrical equivalent model by fitting the model response to the measured frequency response. Microheaters with an active area of140m × 140m have been realized on two different layers(poly-1 andpoly-2) with two different air-gaps (2m and 2.75m). The effective time constants, combining thermal and mechanical responses, are intherangeof0.13msto0.22msforheatersonpoly-1,and1.9s to0.15ms for microheaters on poly-2 layer. The thermal time constants of the best microheaters are in the range of a few s, thus making them suitable for sensor applications that need faster thermal response. The mechanical deformation of the microheaters subjected to an electrothermal excitation, due to thermal stress, is also analyzed using lensless in-line digital holographic microscopy (DHM). The numerically reconstructed holographic images of the micro-heaters clearly indicate the regions under high stress. Double exposure method has been used to obtain the quantitative measurements of the deformations, from the phase analysis of the hologram fringes. The measured deformations correlate well with the theoretical values predicted by a thermo-mechanical analytical model. The results show that lensless in-line DHM with Fourier analysis is an effective method for evaluating the thermo-mechanical characteristics of MEMS components. A sensor interface circuit comprising a resistance-to-time period converter as the front-end circuit and a proportional temperature controller to control the microheater temperature is designed and realized in 130nm UMC CMOS technology. The impact of biasing the transistors in subthreshold versus saturation conditions on analog circuit performance is systematically analyzed. A cascode current mirror, designed in 130nm CMOS technology, is biased in subthreshold and saturation regions and its performance has been analyzed through rigorous analytical modeling. The analytical results have been validated with SPICE simulations. It is demonstrated that the subthreshold operation provides better performance in terms of linearity, power, area, output impedance and tolerance to temperature variation, making it a preferable option for applications such as signal conditioning circuitry for environmental sensors. On the other hand, biasing the circuit in saturation is preferable for applications like transceivers and data converters where high bandwidth, SNR and low sensitivity to process variations are the key requirements. Based on this analysis, a sensor interface circuit has been prototyped for resistance measurement on 130nm CMOS technology, using subthreshold cascode current mirrors as the key building blocks. This current mirror results in 14X lower power compared to above-threshold operation. The interface circuit spans 5 orders of magnitude of resistance, and consumes an ultra low power of 326W. A proportional temperature controller with an integrated on-chip power MOSFET is also realized on the same chip for heating and temperature control of microheaters. The microheater is reused as temperature sensor. The entire circuit works with 1.2V supply, except the power MOSFET and the heater driver circuit, which operate with 3.3V supply. ZnO, a semiconducting metal-oxide, is used as the sensing material. Thin films of ZnO are spin-coated over insulating substrates using sol-gel processing technique. Gold pads deposited over the sensing film act as electrodes. The sensor film is characterized at different temperatures for its sensitivity to ethanol. A peak response of 14% change in resistance is observed for 5ppm ethanol, at a working temperature of 275◦C.

Silicon photonics has become one of the leading candidates for the next generation optical communication platform. In addition to being an inexpensive material and compatible with Complementary metal–oxide–semiconductor (CMOS) manufacturing, silicon exhibits low absorption at optical telecommunication bands. However, high propagation loss and poor light confinement in narrow Si waveguides have limited high-density optical integration.<br>In this work, we show the fabrication and characterization of a novel type of devices named E-skid devices that can reduce the skin depth and suppress the large spatial content of evanescent light. These devices use artificial anisotropic dielectric metamaterial to suppress the evanescent waves. Beside E-skid devices, we also discuss the fabrication and experimental characterization of mode filters using Silicon on Insulator that can block the fundamental TE0 and allow the higher order modes to pass through using Multi Mode Interference.<br>In this work, the mode is filtered using radiation, not by reflection.<br>Beside Silicon, Silicon Nitride has also gained much interest because of its low loss, smaller nonlinear absorption and higher Kerr effect. Silicon Nitride waveguides have widely<br>been used for lots of applications specially the optical frequency comb generation. One special case of coherent optical frequency comb is Soliton in which case the non-linearity and dispersion cancel each other’s effect and keep the pulse without distortion. In this work, we described the Silicon Nitride fabrication process and did a comparative analysis with other research groups who fabricates similar devices. We tried to improve our process by inserting a few additional steps in our fabrication process. We also investigated our process step by step and found out reasons for our low quality factor and low yield. We found a few factors that might be responsible for the low quality factor and addressed them. We fabricated real devices using our modified process and saw improvement in quality factors, yield and thermal performance of the devices.<br>Finally, we describe an edge polishing method for Silicon Nitride microring resonator devices, which we developed from scratch and we can polish edges down to sub-micron level. Thus, the edges become optically flat and it allowed us to do heterogeneous integration with an Indium Phosphide chip. This paves away for some exciting opportunities like on-chip frequency comb generation.<br><br>

<div>A microheater and resistance temperature detector (RTD) are designed and fabricated for various applications. First, a hierarchical manifold microchannel heatsink with an integrated microheater and RTDs is demonstrated. Microfluidic cooling within the embedded heat sink improves heat dissipation, with two-phase operation offering the potential for dissipation of very high heat fluxes while maintaining moderate chip temperatures. To enable multi-chip stacking and other heterogeneous packaging approaches, it is important to densely integrate all fluid flow paths into the device. Therefore, the details of heatsink layouts and fabrication processes are introduced. Characterization of two-phase cooling as well as reliability of the microheater/RTDs are discussed. In addition, another application of microheater for mining particle detection using interdigitated capacitive sensor. While current personal monitoring devices are optimized for monitoring microscale particles, a higher resolution technique is required to detect sub-micron and nanoscale particulate matters (PM) due to smaller volume and mass of the particles. The detection capability of the capacitive sensor for sub-micron and nanoparticles are presented, and an incorporated microheater improved stable capacitive sensor reading under air flow and various humidity. </div><div>This paper also introduces the characterization of nanomaterials such as metallic nanowires (NWs) and single layer graphene. First, the copper nanowire (CuNW)/graphene hybrid networks for transparent conductors (TC) is investigated. Though indium tin oxide (ITO) has been widely used, demands for the next generation of TC is increasing due to a limited supply of indium. Thus, the optical and electrical properties of CuNW/graphene hybrid network are compared with other transparent conductive materials including ITO. Secondly, silver nanowire (AgNW) growth technique using electrodeposition is introduced. A vertically aligned branched AgNW arrays is made using a porous anodic alumina template and the optical properties of the structure are discussed.</div><div><br></div>