A mems thermal microphone and its implementation method

Abstract

The invention discloses a MEMS thermal microphone and a realization method thereof. In the present invention, a back cavity is formed on the substrate, the sensitive beam is placed on the back cavity, and an upper cover plate is arranged on the back cavity to form a standing wave tube; the sound wave enters the standing wave tube from the nozzle of the standing wave tube, and the sound pressure changes The temperature on the sensitive beam is disturbed; at the same time, the sound wave is reflected on the bottom of the standing wave tube, that is, the surface of the back cavity to form a standing wave. The sound pressure at the beam is twice the incident sound pressure at the nozzle of the standing wave tube, so the temperature of the sensitive beam is only proportional to the incident sound pressure, and will not be affected by the vibration velocity of the acoustic particles, eliminating harmonic distortion; The structure of the microphone is similar to that of the thermal acoustic particle velocity sensor, the manufacturing process is the same, and the measurement of sound pressure and acoustic particle velocity can be completed on the same chip.

Description

technical field [0001] The invention relates to microelectromechanical sensing technology, in particular to a MEMS thermal microphone and its realization method. Background technique [0002] Sound is the vibration propagation of medium molecules, the density of the medium corresponds to the change of sound pressure, and the vibration speed of medium molecules corresponds to the vibration velocity of sound particles. Sound pressure is a scalar quantity and can be measured directly with a microphone, while the vibration velocity of sound particles is a vector. Currently, the most effective detection method is based on the thermal principle. The thermal acoustic vector sensor consists of a heating beam and a temperature measuring beam. The heating beam provides a stable thermal field distribution. The temperature measuring beam perceives the disturbance of the thermal field when the acoustic particle vibrates, and measures the vibration velocity of the acoustic particle throug...

AI Technical Summary

Problems solved by technology

[0004] When two sensors are assembled together, the sound center cannot be guaranteed to be at the same point, and the measured sound pressure and vibration velocity signals will have a phase difference;

[0005] Traditional piezoelectric and capacitive microphones are difficult to achieve single-chip integration with thermal acoustic particle vibration velocity sensors due to different manufacturing processes

Images