BrF3 Dry Release Technology for Large Freestanding Parylene MEMS

We report here a dry release technology for making large freestanding surface micromachined Parylene MEMS. The technology is a two-step process that combines wet photoresist dissolution with dry silicon etching by bromine trifluoride (BrF3). With photoresist as the sacrificial layer dissolved using acetone, large Parylene MEMS devices can be achieved. A final dry release in BrF3 vapor helps free the devices. For example, we have successfully fabricated freestanding 1-mm-long cantilevers, 2-mm-long bridges, and 2-mm-diameter diaphragms. These structures are suitable for fully integrated MEMS devices such as accelerometers, gyros and microphones.

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