A diaphragm-gate transistor for MEMS microphones

We present a process that can be manipulated to build pressure transducers very simply, using standard post fabrication procedure. This process is cost efficient, requiring but one extra step subsequent to standard MOSIS fabrication. Strategically placing hollowed insertions, and filling with hydrofluoric acid, allows for the etching of an underlying gate oxide. The resulting cavity turns the layer above it into a diaphragm that produces an output voltage in commensurate with air pressure impingent on the surface. We present an analog circuit used to handle the output signal, and discuss future possibilities for using this device as a microphone.