CMOS-based monolithic MEMS technology and its applications in microwave systems

Silicon technologies such as CMOS and BiCMOS have been traditionally thought of as analog and digital electronic processing mediums. However, this has started changing recently by application of new fabrication techniques borrowed from MicroElectroMechanicalSystems (MEMS). The new methods have revitalized the field and have created enormous new opportunities for these technologies. Integrated systems such as micromachined accelerometers, deformable mirrors, and more recently all-optical routers demonstrate the capabilities of new systems with the additional functions of sensing and actuation integrated with computational capability. These new technologies offer lower-cost, smaller size and higher reliability.; In this work, a new micromachining technology, which is termed CMOS-based Monolithic MEMS Technology (CM-MEMS) is developed. In this technology, the standard CMOS process procedure is followed by a four-mask low-temperature post-processing. The post-process consists of ten steps that include thin and thick-film processing, electroplating, bulk and surface micromachining, and wet and dry etching. Three dimensional, high-aspect-ratio mechanical structures can be fabricated on top of the CMOS chips, without altering the electrical properties of the electronic circuits.; The CM-MEMS technology is capable of meeting the requirements of various applications. The low-frequency applications of this technology include the microfluidic systems, sensor and actuator applications. The most important advantage of CM-MEMS at low-frequency application is that it allows the integration of sensing and actuation functions with the CMOS electronics. Particularly, in this work, the high-frequency applications of the developed technology are investigated. Several crucial components necessary for a microwave communication system are demonstrated including low-loss coplanar transmission lines, filters, power couplers and dividers, antennas, thermopile power sensors. One of the most important aspects of this fabrication approach is that a new class of microwave systems can be developed that utilize mechanical structures to reconfigure electrical properties of the circuit. Analytical and numerical characterization of the developed micromachined components and the verification of the models via measurements are described.