Modelling of a mems microphone using wafer bonding technology

111 p. This dissertation report presents the mathematical modelling of a MEMS capacitive technology microphone that is designed and fabricated based on the advanced wafer bonding technology. A silicon diaphragm and a rigid silicon backplate perforated with acoustic holes constitute the two electrodes of the microphone. The design considerations and specifications of a condenser microphone are briefly presented and discussed. A reliable bulk micro-machining fabrication process for silicon microphones with sensitivity trimming has been proposed and developed. The bonding between the diaphragm and the backplate wafers is accomplished by the application of an Au-Si eutectic bonding technique. The advent of micro-machining technology has inevitably empowered the manufacture of highly sensitive and miniaturized small-signal sensors. However, its inherent small size contributes to a particular class of mechanical noise, which is known as mechanical-thermal noise, as a result of molecular thermal agitation. This mechanical-thermal noise, together with other sources of background noise, establishes the lowest limit of acoustic pressure that can be picked up by the microphone. Verification of a written MATLAB program is performed against three B & K. microphones and the simulated microphone parameters are in good agreement with those values that are cited in established literatures. Master of Science (Precision Engineering)