A Robust Miniature Silicon Microphone Diaphragm

Abstract

A novel miniature silicon microphone diaphragm that is highly robust when subjected to residual stress is described. The novel diaphragm is composed of a reinforced plate supported on carefully designed hinges. An approximate model is developed to account for the effects of the small back volume behind the diaphragm and the narrow slits around the perimeter using finite element analysis and analytical equations. The overall dimensions of the polycrystalline silicon diaphragm are 1mm by 1mm by 40 microns. The measured response of the diaphragm closely resembles 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.

Keywords

• MEMS
• Silicon microphone
• Stress
• Miniature diaphragm
• Fabrication