New fabrication process for high-performance silicon condenser microphone with monocrystalline silicon diaphragm and backplate

This paper reports a new fabrication process for high-performance silicon condenser microphones and its practicability to low-voltage operating microphones. The process requires only two photolithography and wet etching steps to fabricate a complete microphone chip. Prototype microphones were fabricated and tested to investigate the advantages of the process. Experimental results showed that the prototype with a 4-μm-thick diaphragm had excellent acoustic properties such as high sensitivity, a wide dynamic range and a wide frequency range. We conclude that this process can economically mass produce silicon condenser microphones for purposes ranging from broadcasting to personal communications.