MEMS pressure sensor

Abstract

The present invention provides a MEMS pressure sensor and a manufacturing method. The pressure is formed by a top cap wafer, a MEMS wafer and a bottom cap wafer. The MEMS wafer comprises a frame and a membrane, the frame defining a cavity. The membrane is suspended by the frame over the cavity. The bottom cap wafer closes the cavity. The top cap wafer has a recess defining with the membrane a capacitance gap. The top cap wafer comprises a top cap electrode located over the membrane and forming, together with the membrane, a capacitor to detect a deflection of the membrane. Electrical contacts on the top cap wafer are connected to the top cap electrode. A vent is extends from outside of the sensor into the cavity or the capacitance gap. The pressure sensor can include two cavities and two capacitance gaps, to form a differential pressure sensor.

Description

RELATED APPLICATIONS[0001]This patent application claims priority from U.S. 61 / 977,776, the disclosure of which is incorporated therein, in its entirety, by reference.TECHNICAL FIELD OF THE INVENTION[0002]This invention relates to MicroElectroMechanical Systems (MEMS) pressure sensors and more particularly relates to a capacitive MEMS pressure sensor. The invention also relates to a method of manufacturing MEMS pressure sensors.BACKGROUND[0003]Micro-electro-mechanical system (MEMS) devices, in particular inertial sensors such as accelerometers and angular rate sensors or gyroscopes, are being used in a steadily growing number of applications. Due to the significant increase in consumer electronics applications for MEMS sensors such as optical image stabilization (OIS) for cameras embedded in smart phones and tablet PCs, virtual reality systems and wearable electronics, there has been a growing interest in utilizing such technology for more advanced applications which have been tradi...

AI Technical Summary

Benefits of technology

The present invention provides a MEMS pressure sensor that can be integrated into a MEMS 3D System Chip. The sensor includes a top cap wafer, a MEMS wafer, and a bottom cap wafer that are bonded together. The sensor also includes a membrane with a frame and a cavity, and at least one top cap electrode and at least one bottom contact that form capacitors to detect membrane deflection. The sensor can be packaged at the wafer level and has a reduced size. The method for manufacturing the sensor includes steps of providing wafers, patterning the membrane, and bonding the wafers together. The sensor can be used as a differential pressure sensor and has improved accuracy and reliability.

Problems solved by technology

MEMS accelerometers and gyroscopes, being much smaller than traditional mechanical gyroscopes, are subject to higher mechanical noise and drift.

Since position and attitude are calculated by integrating the acceleration and angular rate data, the noise and drift lead to growing errors in position.

A pressure difference across the membrane causes it to deflect.

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