The Design, Fabrication and Characterization of A Novel Miniature Silicon Microphone Diaphragm
W. Cui, R.N. Miles, Q. Su
State University of New York at Binghamton, US
Keywords: MEMS silicon microphone, sound-sensitive diaphragm, stress, robust diaphragm
Abstract:A novel miniature silicon microphone diaphragm is described that is highly robust when subjected to stresses that may arise during the fabrication process. Residual stress produces major challenges in the fabrication of MEMS devices. This is particularly true in the development of MEMS microphones since the response of the thin sound-sensitive diaphragm is strongly affected by stress. In this paper, we demonstrated with a fabricated prototype device that our design approach avoids the difficulties caused by stress in silicon microphones. The novel diaphragm is composed of a reinforced plate supported on carefully designed hinges. The overall dimension of the polysilicon diaphragm is 1mm by 1mm by 40 microns. The measured response of the diaphragm is extremely close to that of an ideal rigid plate over a frequency range extending well beyond the audible range. This approach leads to a structure that is remarkably robust and tolerant of the stresses that have plagued efforts to fabricate miniature microphones. Potential applications include advanced consumer products such as cell phones, portable digital devices, and camcorders.