1. Field of the Invention
The instant disclosure relates to a Micro Electro Mechanical System (MEMS) structure; in particular, a MEMS microphone.
2. Description of Related Art
The applications of microphone are comprehensive; e.g., hearing aids, electronic ears, cellular phones, digital cameras, hand-free telephone handsets, notebook computers and the like. With advancements in various manufacturing methodologies and packaging techniques, it is currently possible to apply semiconductor processes to fabricate the chip-based microphone, also referred as the MEMS microphone, thereby fulfilling the requirements of features like slim size, power-saving, and low manufacturing cost.
Refer initially to FIG. 1, wherein a cross-sectional view of a conventional MEMS microphone is shown. The conventional MEMS microphone 1 as depicted can be essentially characterized in that a circuit (not shown) and an MEMS chip 11 are installed on a base 10 in which the MEMS chip 11 is wire bonded to the circuit on the base 10, and a cover 13 used to cover the MEMS chip 11 is also installed on the base 10. An air chamber 14 is formed in the space between the MEMS chip 11 and the base 10 as a cavity for voice resonance. Voice enters through a voice hole 15 within the cover 13 and generates vibrations with the membrane located on the MEMS chip 11, thus converting the vibration signal into the electronic signal by the MEMS chip 11.
However, in use of such a conventional MEMS microphone, it may pick up not only the user's voices but ambient sounds as well. Therefore, when a user is communicating by means of a cellular phone (not shown) equipped with such a conventional MEMS microphone in a relatively brawling environment, the receiving party may be seriously interfered by noises and not able to clearly hear the user's voices, thus undesirably affecting their dialogs.