A capacitive pressure sensor with high linearity and its preparation method

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 arranged sequentially from bottom to top; the silicon substrate layer is provided with a first cavity and four a lower electrode; a polysilicon support layer and a second cavity are provided in the silicon dioxide layer, and the second cavity communicates with the first cavity; the polysilicon layer includes a movable sensitive film layer, four upper electrodes, and a polysilicon anchor region, each One end of each upper electrode is connected to one end 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 member, the lower electrode is located below the connecting rod, and the upper electrode is close to the movable sensitive film layer. The end face of the thin film layer and the end face of the lower electrode away from the first cavity are in the same plane. The pressure sensor converts the longitudinal displacement change into the transverse area change, has high linearity, and at the same time, the upper and lower plates of the pressure sensor are non-contact, which improves the reliability of the device.

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 layer, 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...

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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