Capacitive MEMS microphone with low-stress ultra-thin vibrating membrane

Emerging consumer electronics such as flexible electronics and smart wearables have strong and growing demand for MEMS microphones with small size and high performance. For a capacitive MEMS microphone, however, it is challenging to achieve reduced size and improved acoustic performance at the same time due to a trade-off between the diameter and mechanical compliance of its vibrating membrane. In this work, a capacitive MEMS microphone with a low-stress polysilicon vibrating membrane was developed to breakthrough the tradeoff, which can achieve a signal-to-noise ratio (SNR) as high as 62.3 dBA. Its vibrating membrane has a thickness of only about 100 and a diameter of 600–800 m.