A micro electrical-mechanical system (MEMS) device comprises a suspended thin film microstructure which includes an anchoring portion adhered to the top surface of the substrate and a suspended portion above the top surface of the substrate. Having a base plane configured in parallel to the substrate, the suspended portion further includes a first recess portion spaced at a first vertical clearance with the substrate, the first vertical clearance being configured differentially smaller than a base clearance of the suspended portion outside the first recess portion. The method for processing a MEMS device includes: depositing a first carbon film, etch-removing a first sacrificial pre-removal portion and an anchor portion of the first carbon film, depositing a second carbon film conformally topping the first carbon film and the substrate, etch-removing the anchor portion of the second carbon film, depositing and patterning the suspended thin film microstructure onto the first carbon film, the second carbon film and the substrate, removing the first carbon film and the second carbon film to release the suspended thin film microstructure above the substrate by selective gaseous oxidation or nitridation preferably enhanced via plasma.