Quasi-differential-capacitor type MEMS pressure sensor and manufacturing method thereof

Abstract

The invention discloses a quasi-differential-capacitor type MEMS pressure sensor and a manufacturing method thereof. The quasi-differential-capacitor type MEMS pressure sensor comprises a first lower electrode (3a), a second lower electrode (3b), a first upper electrode (4a), and a second upper electrode (4b), wherein the first upper electrode (4a) and the second upper electrode (4b) are supported corresponding above the first lower electrode (3a) and the second lower electrode (3b). The first upper electrode (4a) is a pressure sensitive film. A cavity formed between the first upper electrode (4a) and the first lower electrode (3a) is a sealed cavity (9a), so that the first upper electrode (4a) and the first lower electrode (3a) form an air-pressure-sensitive capacitor and the second upper electrode (4b) and the second lower electrode (3b) form a reference capacitor with the electric capacity not changing with the external air pressure. According to the invention, with the pressure capacitor, a common-mode interference signal in an output signal of the air-pressure-sensitive capacitor can be at least filtered partially, thereby improving the stability and resolution of the output signal of the air-pressure-sensitive capacitor.

Description

technical field [0001] The invention relates to the field of sensors, more specifically, to a quasi-differential capacitive MEMS pressure sensor and a manufacturing method thereof. Background technique [0002] The capacitive MEMS pressure sensor is a sensor that uses the capacitance between the pressure-sensitive layer as the upper electrode and the lower electrode to characterize the pressure value acting on the pressure-sensitive layer. Existing capacitive MEMS pressure sensors usually use a single capacitor for pressure detection, such as figure 1 As shown, it includes a substrate 1', an insulating layer 2' formed on the substrate 1', a lower electrode 3' formed on the insulating layer 2', and the pressure on the lower electrode 3' supported by a supporting part 7' Sensitive film, the lower electrode 3' is electrically connected to the lower electrode pad 5', and the pressure sensitive film is used as the upper electrode 4' to be electrically connected to the upper elec...

AI Technical Summary

Problems solved by technology

Since this kind of capacitive MEMS pressure sensor uses a single capacitor for external air pressure detection, it is vulnerable to common-mode interference such as electromagnetic interference, which will cause the output signal of the pressure sensor to be unstable and the resolution will be reduced, which will lead to a decrease in the performance of the chip.

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