Fabrication of Platinum Membrane on Silicon for MEMS Microphone

Platinum membrane with silicon nitride layer is fabricated and analyzed. The membrane, which is designed for MEMS microphone application, is fabricated using sputter platinum and CVD silicon nitride. Membranes with sandwich layer of platinum-nitride-platinum with thickness of 6.35 mum are successfully fabricated. Deflection of the fabricated membrane corresponding to given pressure is measured using Tencor surface profiler. It is observed that deflection at its center is proportional to applied pressure for pressure between 20 Pa to 200 Pa. Average center deflection for applied pressure of 200 Pa is measured to be 0.41 mum. The fabricated platinum membrane is deemed suitable for MEMS microphone application due to its linear deflection response in acoustic pressure range.