Surface-micromachined capacitive differential pressure sensor withlithographically defined silicon diaphragm |
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Authors: | Mastrangelo CH Xia Zhang Tang WC |
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Affiliation: | Dept. of Electr. Eng. & Comput. Sci., Michigan Univ., Ann Arbor, MI; |
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Abstract: | A capacitive surface-micromachined sensor suitable for the measurement of liquid and gas pressures was fabricated. The structure consists of a polysilicon stationary electrode suspended 0.7 μm above a 20-μm-thick lightly doped silicon diaphragm formed by a patterned etch stop. The a priori patterning of the buried etch stop yields diaphragm widths independent of wafer thickness variations with excellent alignment. The design described here has a pressure range of 100 PSI, a nominal capacitance of 3.5 pF with a full scale span of 0.8 pF, and a temperature coefficient of 100 ppm°C-1. Each device, including a matched reference capacitor, occupies 2.9 mm2 , yielding approximately 2000 devices per 100-mm wafer |
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