Presently, microphones have become an important component in various portable consumer electronics, including cellular phones, personal digital assistants and computers. In these applications, size and cost are two critical concerns for microphone design. Silicon based MEMS (Micro-Electro-Mechanical System) microphones have the advantages of offering small size, low cost and ease of integration with CMOS (Complementary Metal-Oxide Semiconductor) circuits. Moreover, the MEMS microphone is also compatible with the surface mount process. Nevertheless, the fundamental challenge of MEMS microphone remains the availability of a reliable fabrication processes to implement the devices.