An MEM microphone carrier module is composed of a substrate and a cover plate. The substrate includes a space layer, a bottom layer, a recession recessed from a top side of the space layer, and a groove formed in the recession. The bottom layer has a metallic plate defining a predetermined pattern and exposed outside a surface thereof. The bottom layer is a single-layer structure formed by the molding of the metallic plate and the insulating glue, such that the substrate is thinner to need lower production cost and take less assembly time than the prior art.