Patent ID: 8374364

Claim:
A manufacturing method of an acoustic sensor, wherein the acoustic sensor comprises: a semiconductor substrate with a back chamber; a vibration thin film arranged on an upper side of the semiconductor substrate; an anchor arranged on an upper surface of the semiconductor substrate; a beam portion integrally extended from the vibration thin film and comprising a distal end supported by the anchor; and a back plate fixed to the upper surface of the semiconductor substrate to cover the vibration thin film and the beam portion with a space, wherein the acoustic sensor converts an acoustic vibration detected by the vibration thin film into a change in electrostatic capacitance between a fixed electrode film arranged on the back plate and the vibration thin film, wherein the manufacturing method comprises: forming a first sacrifice layer and a second sacrifice layer between a surface of the semiconductor substrate and a lower surface of the vibration thin film and the beam portion; covering an upper surface of the vibration thin film and the beam portion with the second sacrifice layer to arrange the vibration thin film and the beam portion in a sacrifice layer comprising the first sacrifice layer and the second sacrifice layer; forming the back plate on the sacrifice layer; forming the back chamber in the semiconductor substrate; removing the first sacrifice layer by etching; and removing one part of the second sacrifice layer by etching after removing the first sacrifice layer by etching to form the anchor between a lower surface of the distal end of the beam portion and the surface of the semiconductor substrate from the remaining second sacrifice layer.