A monolithically integrated MEMS pressure sensor and CMOS substrate using IC-Foundry compatible processes. The CMOS substrate is completed first using standard IC processes. A diaphragm is then added on top of the CMOS. In one embodiment, the diaphragm is made of deposited thin films with stress relief corrugated structure. In another embodiment, the diaphragm is made of a single crystal silicon material that is layer transferred to the CMOS substrate. In an embodiment, the integrated pressure sensor is encapsulated by a thick insulating layer at the wafer level. The monolithically integrated pressure sensor that adopts IC foundry-compatible processes yields the highest performance, smallest form factor, and lowest cost.