Method for fabricating micro-electro-mechanical system (MEMS) device

A method for fabricating a micro-electro-mechanical system (MEMS) device comprising;

• forming a first structural dielectric layer on a substrate;
• patterning the first structural dielectric layer to have a plurality of indent regions without penetrating through the first structural dielectric layer;
• forming a conductive diaphragm layer, wherein the conductive diaphragm layer has a corrugated structure corresponding to the indent regions;
• forming a second structural dielectric layer on the first structural dielectric layer and the conductive diaphragm layer, wherein a suspension layer is embedded in the second structural dielectric layer, and the suspension layer has a protrusion portion to adhere to a portion of the conductive diaphragm layer;
• forming an etching mask layer on the substrate at a back surface, wherein the etching mask layer has a plurality of openings to expose the substrate, in which the openings are at positions corresponding to venting holes to be formed later;
• performing an anisotropic etching process to at least etch the substrate to expose the first structural dielectric layer, wherein the substrate has the venting holes being formed;
• and
• performing an isotropic etching process to release the conductive diaphragm and the suspension layer, wherein the protrusion portion of the suspension layer holds the conductive diaphragm layer and a peripheral end portion of the suspension layer is clamped between the first structural dielectric layer and the second structural dielectric layer.