This paper studies the effect of thin film thickness on visibility readout from an interferometric pressure sensor. Interference fringes between a silicon nitride diaphragm and a glass substrate are formed as a function of pressure and can be captured using a camera. Image processing software was used to analyze and correlate the fringe pattern to pressure. Visibility of the interference fringes is optimized by depositing a thin silicon nitride layer on the glass substrate of the sensor using plasma enhanced chemical vapor deposition (PECVD). Optimal visibility was obtained with a coating thickness of 79 nm. Visibility was increased by 150% in comparison to no coating.

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