A low-voltage bulk-silicon tunneling-based microaccelerometer with CMOS interface circuitry.
1996
Hochschulschrift
Zugriff:
The development of high-performance, low-power, solid-state microsensors has become a very important goal for different applications. Using the ultrasensitive relation of the tunneling current to the tunneling distance, a new category of sensors has emerged recently. This doctoral research involves the design, fabrication, and testing of a low-voltage bulk-silicon tunneling-based microaccelerometer with CMOS interface circuitry. Accelerometers are used as a vehicle to explore the fundamental characteristics and limitations of tunneling-based microsensors as well as to investigate overall issues in their fabrication and utilization in practical applications. Bulk micromachining technology and the boron etch-stop dissolved wafer process have been successfully utilized in device fabrication. A four-hour, 1100$\sp\circ$C oxygen, post-diffusion annealing process has been developed to eliminate the stress gradient and warpage associated with thin heavily-boron-doped silicon microstructures. The 1.2$\mu$m, n-well CMOS interface circuitry has been designed and fabricated through MOSIS. Analytical and root-locus methods are employed to understand the correlations between various design and performance parameters. An electromechanical model has been also developed for both the sensor and circuit to simulate and predict device behavior using HSPICE. The microaccelerometer and its CMOS interface circuit chip have been wire-bonded and mounted together in a metallic package to form a compact sensing module. Only a single 12V battery is needed to operate the device with a power dissipation of 2.5mW. With an active area of $\rm400\times400\mu m\sp2,$ the device has a sensitivity of 125mV/g, bandwidth of 2.5kHz, and measurement range of 30g. The noise spectral density with a 1/f behavior drops from 4mg/$\surd$Hz at 0.5Hz to 0.1mg/Hz at 2.5kHz, which corresponds to a resolution of 8mg. Without power interruption, the long-term variations in the offset output voltage and device sensitivity are $\pm$10mV ($\approx$0.12%) and $\pm$0.2mV/g ($\approx$0.15%) in a continuous operation over thirty days. Temperature coefficients of offset and sensitivity are measured to be $-$550ppm/$\sp\circ$C and 940ppm/$\sp\circ$C, respectively.
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A low-voltage bulk-silicon tunneling-based microaccelerometer with CMOS interface circuitry.
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Autor/in / Beteiligte Person: | Yeh, Chingwen |
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Veröffentlichung: | 1996 |
Medientyp: | Hochschulschrift |
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