The MEMS microphone is a representative device among the MEMS family, which has attracted substantial research interest, and those tailored for human voice have earned distinct success in commercialization. Although sustained development persists, challenges such as residual stress, environmental noise, and structural innovation are posed. To collect and summarize the recent advances in this subject, this paper presents a concise review concerning the transduction mechanism, diverse mechanical structure topologies, and effective methods of noise reduction for high-performance MEMS microphones with a dynamic range akin to the audible spectrum, aiming to provide a comprehensive and adequate analysis of this scope.

This paper presents a robust, highly scalable top-down fabrication methodology for the monolithic integration of sub-micron piezoresistive silicon nanowires (SiNWs) into microelectromechanical systems (MEMS). Unlike conventional top-down approaches, this method eliminates the reliance on expensive electron-beam lithography, anisotropic KOH wet etching, or complex epitaxial growth. Starting with a heavily doped n-type silicon-on-insulator wafer, micro-scale ultra-thin SiO ₂ and photoresist composite masks are defined via standard ultraviolet photolithography. A subsequent combination of deep reactive ion etching (DRIE) and thermal oxidation precisely scales the structures down to the true nanoscale (width 510 nm, thickness 230 nm) while simultaneously smoothing the DRIE-induced sidewall scallops. A fully dry structural release using vapor-phase hydrofluoric acid completely prevents liquid-induced stiction, ensuring high fabrication yield. Electromechanical characterization via four-point bending reveals a pronounced size-dependent piezoresistive enhancement. The fabricated SiNWs achieve a high longitudinal gauge factor of −116 and a piezoresistance coefficient ( π l ) of − 68.6 × 10 − 11 P a − 1 along the 〈110〉 crystallographic direction, substantially surpassing the theoretical limits of conventional heavily doped bulk silicon. Finally, the successful implementation of these SiNWs within an integrated MEMS accelerometer structure demonstrates the remarkable robustness and CMOS compatibility of this ‘nanowire-first’ process, offering a highly scalable pathway for next-generation ultra-sensitive physical sensors.