Capacitive pressure sensor with high linearity and manufacturing method thereof

Abstract

The invention discloses a capacitive pressure sensor with high linearity. The pressure sensor comprises a silicon substrate layer, a silicon dioxide layer and a polysilicon layer which are successively arranged from bottom to top. The silicon substrate layer is provided with a first cavity and four lower electrodes. The silicon dioxide layer is provided with a polysilicon supporting layer and a second cavity. The second cavity is connected to the first cavity. The polysilicon layer comprises a movable sensitive film layer, four upper electrodes and a polysilicon anchor area. One end of each upper electrode is connected to one end surface of the movable sensitive film layer through a connecting rod. The other end of each upper electrode is connected to the polysilicon anchor area through an elastic component. The lower electrodes are located below the connecting rod. End surfaces of the upper electrodes, which are close to the movable sensitive film layer, and end surfaces of the lower electrodes, which are far away from the first cavity, are in a same surface. The pressure sensor converts a longitudinal displacement change into a transverse area change so that the high linearity is possessed. Simultaneously, upper and lower pole plates of the pressure sensor are non-contacted so that device reliability is increased.

Description

technical field [0001] The invention relates to a pressure sensor, in particular to a capacitive pressure sensor with high linearity and a preparation method thereof. Background technique [0002] Among the products realized by silicon micromachining technology, the pressure sensor is a relatively mature category. At present, pressure sensors have been widely used in various industrial and biomedical fields. Capacitive pressure sensors have gradually become a hot spot for pressure sensors due to their high sensitivity, better temperature performance, low power consumption, no temperature drift, firm structure, and little influence from external stress. The traditional variable-area capacitive pressure sensor is also called a contact capacitive sensor. When the pressure is applied to the movable sensitive film, the output capacitance of the sensor is changed by changing the contact area of ​​the two polar plates. Since the two polar plates of the sensor are in contact with ...

AI Technical Summary

Problems solved by technology

Since the two polar plates of the sensor are in contact with each other, the two polar plates may not be separated when the pressure is removed, and may stick together, which may cause a problem of low reliability.

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