Mems device with multiple electrodes and fabricating method thereof

A MEMS device with multiple electrodes, being adapted to sense air pressure, comprising:

• a substrate;
• a first electrode on the substrate;
• a second electrode configured to define a sensing capacitor between the first electrode and the second electrode;
• and
• a third electrode on the substrate, configured to define a stationary capacitor;
• wherein the third electrode disconnects from the second electrode or the third electrode disconnects from the first electrode, a pointing direction of the first electrode is in parallel with a normal direction of the substrate, a pointing direction of the third electrode is perpendicular to the pointing direction of the first electrode.

A MEMS device with multiple electrodes, comprising:

• a substrate;
• a first electrode on the substrate, wherein a pointing direction of the first electrode is in parallel with the normal direction of the substrate;
• a second electrode on the substrate, including a sensing portion and a stationary portion;
• and
• a third electrode on the substrate, wherein a pointing direction of the third electrode is perpendicular to the pointing direction of the first electrode;
• wherein the sensing portion faces the first electrode, the stationary portion faces the third electrode, when the sensing portion deforms, the stationary portion and the third electrodes are spaced apart by a predetermined constant distance.

A fabricating method of a MEMS device with multiple electrodes, the method comprising the following steps:

• providing a Silicon On Insulator (SOI) wafer, wherein the SOI wafer includes a device layer, an electrical insulation layer and a handle layer, wherein the electrical insulation layer is disposed between the device layer and the handle layer;
• etching the device layer to form a recession;
• etching the device layer having the recession to form a plurality of slots which expose the electrical insulation layer and to form a through hole which exposes the electrical insulation layer, wherein the slots and the recession define the second electrode which includes a sensing portion and a stationary portion, the through hole is disposed in the stationary portion, the slots also define the third electrode and a conductive post which is disposed inside the through hole and is electrically insulated from the stationary portion;
• to providing a substrate wafer on which a first electrode is disposed;
• bonding the SOI wafer and the substrate wafer through wafer-to-wafer bonding to allow the second electrode and the third electrode to connect to a top surface of the substrate wafer, wherein the sensing portion faces the first electrode, the stationary portion faces the third electrode, and a pointing direction of the third electrode is perpendicular to a pointing direction of the first electrode;
• and
• removing the handle layer.