Soft support bridge type silicon micro-piezoelectric microphone chip and prepration method thereof

Abstract

The invention relates to a soft support bridge type silicon micro-piezoelectric microphone chip which comprises a silicon substrate with a square conical hole which is small at the top and big at thebottom, a square compound vibration membrane which consists of a first silicon nitride membrane layer, a silicon dioxide membrane layer and a second silicon nitride membrane layer is covered on the front surface of the silicon substrate, and a third silicon nitride membrane layer and a fourth silicon nitride membrane layer are sequentially covered on the back surface of the silicon substrate; thethird and the fourth silicon nitride membrane layers both have central square holes; one pair of opposite sides of the vibration membrane respectively etch a vertical narrow slot penetrating the vibration membrane, and the vertical projection of each narrow slot is positioned on the inner side of the edge of the square hole in the front surface of the silicon substrate; a lower electrode, a piezoelectric membrane and an upper electrode are sequentially deposited on the vibration membrane; a polyimide membrane is deposited on various parts on the front surface of the silicon substrate; the compound vibration membrane which is etched with the vertical narrow slots and the polyimide membrane commonly constitute a soft support anti-sound leakage bridge type vibration membrane; two sides of thevibration membrane are fixedly supported, and strain can be produced during the vibration process; in order to prevent the microphone from producing sound leakage through the narrow slots, the soft polyimide membrane is deposited on the narrow slots, thereby being capable of effectively preventing sound leakage phenomenon.

Description

technical field [0001] The invention relates to the field of silicon micro-piezoelectric microphones, in particular to a silicon micro-piezoelectric microphone chip and a preparation method thereof. Background technique [0002] Silicon micro-microphones mainly include piezoelectric and capacitive types. Silicon micro-piezoelectric microphones are composed of piezoelectric layers, vibrating membranes, and metal electrodes. Compared with the silicon microcapacitor microphone, the piezoelectric microphone has a simple structure and does not require a bias voltage; it has low impedance and can be used as a transmitter to achieve both reception and transmission; it can be applied to miniature microphones, ultrasonic imaging, and hydrophones. However, its sensitivity is relatively low, and an important factor limiting its sensitivity is that the stress of the vibrating membrane is relatively large, so when the microphone vibrates, the sensitivity of the microphone is relatively l...

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Problems solved by technology

However, its sensitivity is relatively low, and an important factor limiting its sensitivity is that the stress of the vibrating membrane is relatively large, so when the microphone vibrates, the sensitivity of the microphone is relatively low due to the small strain of the piezoelectric layer.

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