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A single axis (Z-axis) accelerometer is being designed. Suppose the chosen transduction principle is electrostatic sensing. Compare the pros and cons of the following two configuration options. Compare the following perspectives: (1) ease of fabrication; (2) sensitivity; (3) compatibility with low cost manufacturing.
|1||parallel capacitor introduces large capacitance value;||since the bottom metal electrode is to be covered by LPCVD
sacrificial and structural layers, the material integrity is questionable;
on the flip side, the sacrificial and structural layers may dictate the choice of metal electrode on the bottom.
|2||the electrodes are both made of polycrystal silicon, and hence the processing does not involve metal layer as in option 1.||the sensing is based on comb drive capacitors, which may be smaller than the parallel plate capacitor depending on the design.|