Micro-pressure sensor and manufacturing and detecting method thereof

Abstract

The invention provides a micro-pressure sensor and a manufacturing and detecting method thereof. The sensor mainly comprises an upper thin plate, a middle thin plate and a base from top to bottom. An upper cavity is formed by the middle thin plate, the upper thin plate and an upper strut, and the upper surface of the middle thin plate or the lower surface of the upper thin plate is provided with an upper insulating layer. A lower cavity is formed by the middle thin plate, the base and a lower strut, and the lower surface of the middle thin plate or the upper surface of the base are provided with a lower insulating layer. The upper thin plate serves as a sensor pressure sensitive element, the middle thin plate serves as a resonant element of the sensor, and the upper thin plate, the middle thin plate and the base serve as the upper electrode, the middle electrode and the lower electrode of the sensor. During pressure measuring, the electrostatic force borne by the middle thin plate changes due to the deformation, caused by pressure, of the upper thin plate, the resonant frequency of the middle thin plate changes, and pressure measuring can be achieved through the relation between the resonant frequency and the pressure change. The sensitivity of the sensor can be improved, and high-sensitivity detecting for micro-pressure is achieved conveniently.

Description

Technical field: [0001] The invention relates to MEMS and pressure detection technology, in particular to a micro pressure sensor and its preparation and detection method. Background technique: [0002] Micro pressure sensors have urgent needs and wide applications in the fields of industrial control, medical equipment, aerospace and military weapons, so the research on this type of sensors has important practical significance. With the development of MEMS (Micro Electro-Mechanical Systems, micro-mechanical electronic systems) technology, MEMS micro-pressure sensors have been widely used in the field of micro-pressure measurement. There are three main types of MEMS micro pressure sensors: piezoresistive, capacitive and resonant. The piezoresistive micro-pressure sensor mainly uses the piezoresistive effect of silicon to measure the measured pressure through the change of the output voltage of the Wheatstone bridge integrated in the film after the silicon film is pressed. A...

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Problems solved by technology

Although its output has a good linear relationship with the input, the temperature sensitivity of the force sensitive resistor in the silicon film requires the sensor to implement temperature compensation, which increases the complexity of the measurement. At the same time, the integration of the Wheatstone bridge in the silicon film makes its thin film It is difficult to further reduce the thickness under the condition of ensuring the measurement accuracy to achieve pressure measurement with smaller range and higher sensitivity

The capacitive silicon micro pressure sensor converts the pressure change into a capacitance change by using the change of the capacitance pole distance. It has a series of advantages such as good temperature stability, high sensitivity, low power consumption, and further miniaturization becomes relatively simple. However, its output and input poor linearity

The resonant silicon micro pressure sensor uses the natural frequency of the resonant beam to change with the change of the applied axial force to achieve pressure measurement. Although its measurement accuracy, stability and resolution are better than the above two, in order to ensure a higher Quality factor, the sensor chip needs to be vacuum sealed, so the structure is complex, the processing is difficult, and the cost is high

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