| 摘要 |
This invention provides an acoustic sensor capable of increasing the length of the portion of the beam portion not fixed with the anchor without lowering the strength of the beam portion and the supporting strength of the diaphragm. On an upper surface of a silicon substrate (32), a beam portion (36a) of a diaphragm (33) made of polysilicon is formed through a second sacrifice layer (47) made of silicon dioxide film on an extended portion (48a) of a first sacrifice layer (48) made of polysilicon. The extended portion (48a) is formed under a region excluding a distal end of the beam portion (36a). The extended portion (48a) is removed by etching from a back chamber (35) arranged in the silicon substrate (32) to form a hollow portion (50) in a region excluding the distal end of the lower surface of the beam portion (36a), and then the second sacrifice layer (47) is removed by etching. In this case, the second sacrifice layer (47) is left on the lower surface of the distal end of the beam portion (36a) to obtain an anchor (37).
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