A method for fabricating a MEMS device comprises providing a substrate having a back side, a front side opposite to the back side and a periphery portion. A desired microstructure is formed on the back side of the substrate. The substrate is then supported for rotation. A precursor solution is deposited on the front side of the substrate during rotation so that a thin film layer may be formed thereon. During formation of the thin film layer, the substrate is supported and rotated that the microstructure formed on the back side is protected.