Abstract: The present invention provides a MEMS microphone comprising (i) a substrate layer, (ii) a fixed backplate, and (iii) an intermediate layer sandwiched between the substrate layer and the fixed backplate. The substrate layer has a first opening through the thickness of the substrate layer. The intermediate layer has a second opening through the thickness of the intermediate layer. The fixed backplate forms a ceiling of the second opening, and the second opening is larger than the first opening and extends into the first opening, forming a looped recess (“undercut”). The looped recess is defined by a looped ledge on the substrate, a looped sidewall around the second opening, and a looped ceiling from the fixed backplate. The looped sidewall and the looped ceiling are made of a same material.

Abstract: The present invention provides a capacitive microphone such as a MEMS microphone with two capacitors. The signal output from the first capacitor is additive inverse of that from the second capacitor, and a total signal output is a difference between the two outputs. In at least one of the two capacitors, a movable or deflectable membrane/diaphragm moves in a lateral manner relative to the fixed capacitor plate, instead of moving toward/from the fixed plate. The squeeze film damping, and the noise are substantially avoided, and the performances of the microphone is significantly improved.

Abstract: The present invention provides a capacitive microphone such as a MEMS microphone with two capacitors. The signal output from the first capacitor is additive inverse of that from the second capacitor, and a total signal output is a difference between the two outputs. In at least one of the two capacitors, a movable or deflectable membrane/diaphragm moves in a lateral manner relative to the fixed capacitor plate, instead of moving toward/from the fixed plate. The squeeze film damping, and the noise are substantially avoided, and the performances of the microphone is significantly improved.

Abstract: The present invention provides a MEMS microphone comprising (i) a substrate layer, (ii) a fixed backplate, and (iii) an intermediate layer sandwiched between the substrate layer and the fixed backplate. The substrate layer has a first opening through the thickness of the substrate layer. The intermediate layer has a second opening through the thickness of the intermediate layer. The fixed backplate forms a ceiling of the second opening, and the second opening is larger than the first opening and extends into the first opening, forming a looped recess (“undercut”). The looped recess is defined by a looped ledge on the substrate, a looped sidewall around the second opening, and a looped ceiling from the fixed backplate. The looped sidewall and the looped ceiling are made of a same material.

Abstract: The present invention provides a process of fabricating a capacitive microphone such as a MEMS microphone with two capacitors. The two capacitors may be so fabricated that the signal output from the first capacitor is additive inverse of that from the second capacitor, and a total signal output is a difference between the two outputs. In at least one of the two capacitors, a movable or deflectable membrane/diaphragm moves in a lateral manner relative to the fixed capacitor plate, instead of moving toward/from the fixed plate. The squeeze film damping, and the noise are substantially avoided, and the performances of the microphone are significantly improved.

Abstract: The present invention provides a process of fabricating a capacitive microphone such as a MEMS microphone with two capacitors. The two capacitors may be so fabricated that the signal output from the first capacitor is additive inverse of that from the second capacitor, and a total signal output is a difference between the two outputs. In at least one of the two capacitors, a movable or deflectable membrane/diaphragm moves in a lateral manner relative to the fixed capacitor plate, instead of moving toward/from the fixed plate. The squeeze film damping, and the noise are substantially avoided, and the performances of the microphone are significantly improved.

Abstract: The present invention provides a capacitive microphone such as a MEMS microphone with two capacitors. The signal output from the first capacitor is additive inverse of that from the second capacitor, and a total signal output is a difference between the two outputs. In at least one of the two capacitors, a movable or deflectable membrane/diaphragm moves in a lateral manner relative to the fixed capacitor plate, instead of moving toward/from the fixed plate. The squeeze film damping, and the noise are substantially avoided, and the performances of the microphone is significantly improved.

Abstract: The present invention provides a capacitive microphone such as a MEMS microphone with two capacitors. The signal output from the first capacitor is additive inverse of that from the second capacitor, and a total signal output is a difference between the two outputs. In at least one of the two capacitors, a movable or deflectable membrane/diaphragm moves in a lateral manner relative to the fixed capacitor plate, instead of moving toward/from the fixed plate. The squeeze film damping, and the noise are substantially avoided, and the performances of the microphone is significantly improved.