MEMS chip and processing method thereof, and MEMS microphone

Abstract

The invention discloses an MEMS chip and a processing method thereof, and an MEMS microphone, the MEMS chip comprises a silicon substrate, a diaphragm layer and a back polar plate, a cavity is formed in the silicon substrate, the cavity extends from a first side to a second side of the silicon substrate so as to form a first opening located at the first side of the silicon substrate and a second opening located at the second side of the silicon substrate. The cavity is provided with an expansion section between the first opening and the second opening, and the cross sectional area of the cavity at the expansion section is larger than that at the first opening and the second opening. In the MEMS chip provided by the invention, the volume of the cavity is increased due to the arrangement of the expansion section so as to obtain better acoustic performance; meanwhile, the areas of the openings in the two sides of the silicon substrate are smaller than the cross sectional area of the expansion section, so that the size of the acoustic sensor chip does not need to be increased along with the increase of the volume of the cavity, and the acoustic sensor chip can be manufactured into a smaller size; therefore, the increase of the manufacturing cost of the MEMS chip is controlled.

Description

technical field [0001] The invention relates to the technical field of micro-electromechanical processing, in particular to a MEMS chip, a processing method thereof, and a MEMS microphone. Background technique [0002] MEMS chips are usually packaged to form a front cavity and a back cavity. The front cavity is equivalent to a Helmholtz resonator, which affects the high-frequency response of the microphone, and the back cavity is an acoustic space that affects the low-frequency response of the microphone. In order to obtain better acoustics performance, the volume of the anterior cavity should be reduced and the volume of the posterior cavity increased as much as possible. [0003] For the microphone whose sound hole is formed on the top, the back cavity is a cavity formed by a silicon substrate through a dry or wet process. However, increasing the size of the cavity generally means increasing the size of the acoustic sensor chip, which obviously leads to an increase in man...

AI Technical Summary

Problems solved by technology

However, increasing the cavity size usually means increasing the size of the acoustic sensor chip, which obviously leads to an increase in manufacturing costs

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