Potential of MEMS technologies for manufacturing of high-fidelity microspeakers

The use of microspeakers has drastically grown over the past few years in reason of the important increase of mobile electronics devices having sound reproduction functions. Consumer electronics devices such as mobile phones, tablets or camcorders are the most representative exemples of everyday used devices with embedded microspeakers. Since 2009, this market exceeds one billion microspeakers per year. However, in parallel to the sales increase, the performances of these small-size transducers have been only very little improved in terms of sound quality, efficiency and power density over the last decade. Several reasons can explain such stagnation, such as the limits of conventional manufacturing techniques, or the focus put on selling points other than sound reproduction. The proposal made here is to take advantage of Microsystems technologies for improving microspeaker's performances. Indeed, such a technological leap appears as a very promising way to overcome the major shortcomings of micro speakers made using conventional technologies. This paper illustrates, in the case of a silicon microspeaker, the gains that can be expected from MEMS technologies. The design and the microfabrication process of the device will be fully detailed. Experimental acoustic chacacteristics will be compared to that of conventional microspeakers of same size and power range.