Piezoresistive microphone with integrated amplifier realized using metal-induced laterally crystallized polycrystalline silicon

Compared to conventional polycrystalline silicon (poly-Si), high-temperature re-crystallized (RC) metal-induced laterally crystallized (MILC) poly-Si has significantly improved material, mechanical and electrical properties, thus potentially allowing sensor and electronic integration on non-silicon-based substrates. In this paper, a RC-MILC poly-Si piezoresistive microphone with integrated amplifier has been designed, fabricated and tested. Measured results indicate an airborne sound sensitivity of 50 μV Pa ^-1 and a flat frequency response within ±3 dB between 100 Hz and 8 kHz. Using RC-MILC poly-Si, piezoresistors with gauge factor improved about 25%, noise level reduced about 50% and transistors with performance approaching that of single-crystal silicon devices have been realized.