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.