| abstract |
(57) [Problem] To provide a microphone for a photoacoustic gas sensor having a simple configuration capable of increasing the detection sensitivity of the photoacoustic gas sensor. SOLUTION: A corrugated first electrode 21 provided so as to form a part of a wall surface of a cavity 10 is supported by a back plate 23 connected to the cavity, and a predetermined electrode is provided on the back side of the first electrode. A second electrode 22 that is opposed to the first electrode 22 at a distance. In particular, the first electrode is formed by using a corrugated shape obtained by anisotropically etching one surface of the Si substrate 11 for forming the cavity, and the sacrificial layer 16 is formed thereon. To form a second electrode and further form a back plate. Then, the Si substrate is selectively etched from the back side to expose the first electrode to form a cavity, and the sacrifice layer is removed by etching to complete the microphone. |