Micro-electro-mechanical system (MEMS) device and fabrication method thereof

A method of fabricating a micro-electro-mechanical system (MEMS) device, comprising:

• providing a supporting substrate;
• etching the supporting substrate to form a cavity and a stopper at a top surface of the supporting substrate, wherein the stopper is adjacent to the cavity, and a top surface of the stopper and the top surface of the supporting substrate are on the same level in a height;
• forming a bonding dielectric layer on the top surface of the supporting substrate and on a top surface of the stopper;
• disposing a MEMS device layer on the bonding dielectric layer, wherein the MEMS device layer is bonded to the stopper and the supporting substrate, wherein the bonding dielectric layer is disposed between the top surface of the supporting substrate and a bottom surface of the MEMS device layer, and;
• patterning the MEMS device layer to form a MEMS structure, wherein the MEMS structure comprises a proof mass bonded to the stopper, a suspension beam formed directly above the cavity, a protruding portion, and a conductive wire disposed on the protruding portion, and the conductive wire is bonded to a bonding pad of a complementary metal oxide semiconductor (CMOS) wafer so as to form a sequential stack of the protruding portion, the conductive wire and the bonding pad;
• and
• removing a portion of the bonding dielectric layer disposed between the stopper and the proof mass to form a gap between the stopper and the proof mass.