Acoustic sensor and method of manufacturing the same

摘要

An acoustic sensor lengthens 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, a beam portion made of polysilicon is formed through a second sacrifice layer made of silicon dioxide film on an extended portion of a first sacrifice layer made of polysilicon. The extended portion is formed under a region excluding a distal end of the beam portion. The extended portion is removed by etching from a back chamber arranged in the silicon substrate to form a hollow portion in a region excluding the distal end of the lower surface of the beam portion, and then the second sacrifice layer is removed by etching. The second sacrifice layer remaining on the lower surface of the distal end of the beam portion forms an anchor.