Capacitive sound pressure hydrophone based on MEMS technology and preparation method thereof

Abstract

The invention relates to a capacitive sound pressure hydrophone based on the MEMS technology and a preparation method thereof. The hydrophone comprises a glass substrate, a ring-shaped silicon supportand a silicon dioxide vibration film. A capacitor cavity is encircled by the silicon dioxide vibration film, the ring-shaped silicon support and the glass substrate. A disk-shaped metal aluminum lower electrode is arranged on the top surface of the glass substrate; and a disk-shaped metal aluminum upper electrode is arranged on the top surface of the silicon dioxide vibration film. Four circularoil injection holes communicated with the capacitor cavity are distributed in the silicon dioxide vibration film uniformly around the disk-shaped metal aluminum upper electrode; and the capacitor cavity is filled with silicone oil through the circular oil injection holes. According to the invention, the capacitive sound pressure hydrophone has advantages of small size, high sensitivity, and good hydrostatic-pressure-resistant capability; the process flow is simplified; production in batches is realized; and the cost is lowered. With the hydrophone, the underwater sound pressure measurement under the conditions of the frequency response range of 5Hz to 2kHz, the hydrostatic-pressure-resistant capability of over 20MPa and the sensitivity of over -160dB is realized.

Description

technical field [0001] The invention belongs to the technical field of MEMS, in particular to a capacitive sound pressure hydrophone based on MEMS technology and a preparation method thereof. Background technique [0002] The continents on the earth's surface are covered by oceans with a total area of ​​about 360 million square kilometers, which accounts for about 71% of the earth's surface area. However, as of today, the ocean has only been explored by humans. %. The ocean is a treasure house with great potential because it contains a large number of mineral resources, biological resources and chemical resources. [0003] Underwater sound pressure detection is an important part of underwater detection. Using accurate sound pressure information combined with sound pressure gradient information can accurately obtain the azimuth and distance of underwater targets, and can also effectively use sound pressure hydrophones to monitor the marine environment. monitor. At present,...

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Problems solved by technology

At present, common sound pressure hydrophones are classified into piezoelectric, piezoresistive and capacitive according to their working principles. Piezoelectric sound pressure hydrophones are made of the positive (inverse) piezoelectric effect of piezoelectric materials. This type The processing technology of the sensor is simple, the price is low, and it is widely used, but there is a prominent impedance mismatch problem with the gas or liquid medium, which will affect the important parameters such as the sensitivity, bandwidth and electromechanical conversion efficiency of the sensor; As a result, the sound pressure can be measured by changing the resistance value of the Wheatstone bridge arm resistance by feeling the sound pressure and then changing the output voltage. The linearity is good and the detection method is simple, but with the change of temperature, the piezoresistive coefficient and resistance The rate will also change, which is not conducive to underwater sound pressure measurement with changing temperature conditions; capacitive sound pressure hydrophones feel the sound pressure through the vibrating membrane, and the distance between the upper and lower plates changes, resulting in a change in capacitance

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