Capactive micro-machined ultrasonic transducer (CMUT)-based super-low range pressure sensor and preparation method thereof

Abstract

The invention provides a capactive micro-machined ultrasonic transducer (CMUT)-based super-low range pressure sensor and a preparation method thereof. The overall structure of the pressure sensor comprises a metal aluminum upper electrode, a silicon dioxide thin film, a silicon dioxide supporting post, a monocrystal silicon base, a silicon nitride insulating layer and a metal aluminum lower electrode, which are arranged in sequence from top to bottom. The silicon dioxide thin film is formed by oxidation technology and is up to tens of nanometers in thickness, so the sensitivity of the sensor is improved and measurement on lower pressure is realized. The silicon nitride insulating layer electrically isolates the lower electrode and the monocrystal silicon base completely, so a series of unstable conditions of sensing charge generation in the monocrystal silicon base, lower electrode expansion and the like which are caused by the direct connection between the lower electrode and the monocrystal silicon base are avoided. The size of the electrodes can be precisely designed, parasitic capacitance is reduced, and the working performance of a CMUT and the accuracy of pressure measurement are improved.

Description

Technical field [0001] The invention belongs to the technical field of MEMS, and relates to a CMUT-based ultra-low range pressure sensor and a preparation method thereof. Background technique [0002] The ultra-low range pressure sensor is mainly used to measure extremely small pressure changes. With the rapid development of science and technology, this type of low-range pressure sensor has urgent needs and wide applications in industrial control, environmental protection equipment, medical equipment, aerospace, and military weapons. Therefore, the research on this type of sensor Has extremely important practical significance. [0003] At present, silicon micro pressure sensors based on MEMS (Micro Electro-Mechanical Systems) technology have dominated the field of ultra-low range pressure sensors and have been widely used commercially. Silicon micro pressure sensors work according to their work The principle can be divided into the following three types: piezoresistive, capacitiv...

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Problems solved by technology

At present, although CMUT has been widely used in medical, biological, chemical, military and other fields, there are no relevant reports on the application of ultra-low and micro-pressure measurement.

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