A monolithically integrated MEMS and CMOS substrates provided by an IC-foundry compatible process. The CMOS substrate is completed first using standard IC processes. A diaphragm with stress relief corrugated structure is then fabricated on top of the CMOS. Air vent holes are then etched in the CMOS substrate. Finally, the microphone device is encapsulated by a thick insulating layer at the wafer level. The monolithically integrated microphone that adopts IC foundry-compatible processes yields the highest performance, smallest form factor, and lowest cost. Using this architecture and fabrication flow, it is feasible and cost-effective to make an array of Silicon microphones for noise cancellation, beam forming, better directionality and fidelity.