Date

2010

Author

Ocak, İlker Ender

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Micromachining technologies enabled the use of miniaturized transducers in many high technology sensing systems. These transducers have many advantages like small-size, low-cost and high-reliability. One of the applications micro-machined transducers are used is inertial navigation systems, where the exact position of a moving frame is continuously monitored by tracking the linear and angular motions of the frame. Other than navigation applications, inertial sensors are used in health and military applications as well as consumer electronics. Today accelerometers capable of measuring accelerations from 0.5g-1g range up to several thousand g’s are commercially available in the market which have been fabricated using micromachining technologies. The aim of this research is to develop such a state-of-the-art micro-machined accelerometer system, whose performance is expected to reach tactical-grade level. In order to achieve these performance values a MATLAB algorithm is developed to optimize the accelerometer performances in the desired levels. Expected performance parameters of the designed accelerometer structures are extracted from the simulations done by both Coventorware finite element modeling tool and MATLAB. Designed structures are then fabricated with silicon-on-glass, dissolved wafer and dissolved epitaxial wafer processes. These fabrication results are compared and it is observed that highest yield accelerometers are fabricated with the SOG process. But these accelerometers could not be able to satisfy tactical grade performance parameters. Best performances are obtained with DWP, but due to high internal stress, yield of the sensors were very low. DEWP increased the yield of this process from 2-3% to 45-50% but the expected operation range of the designs dropped to ±12.5g range. Using the fabricated accelerometers in DEWP a three axial accelerometer package is prepared and tests results proved that this three axial accelerometer system was satisfying the tactical grade requirements. In addition to these a three axial monolithic accelerometer fabrication technique is proposed and sensors are designed which are suitable for this process. Best performances achieved with single axis accelerometers were 153µg/√Hz noise floor, 50µg bias drift, 0.38% non-linearity and a maximum operation range of 33.5g which has the higher dynamic range among its counterparts in the literature. Performance results achieved with the three axes accelerometer were ~150µg bias drift, <200µg/√Hz noise density, ~0.4% non-linearity with higher than ±10g operation range.

Subject Keywords

Electronics., Acceleroemeter., Micro-Electro-Mechanical Systems (MEMS).

URI

http://etd.lib.metu.edu.tr/upload/12612724/index.pdf
https://hdl.handle.net/11511/20773

Collections

Graduate School of Natural and Applied Sciences, Thesis