This invention relates to a MOS device for making the source/drain region closer to the channel region and a method of manufacturing the same, comprising: providing an initial structure, which includes a substrate, an active region, and a gate stack; performing ion implantation in the active region on both sides of the gate stack, such that part of the substrate material undergoes pre-amorphization to form an amorphous material layer; forming a first spacer; with the first spacer as a mask, performing dry etching, thereby forming a recess, with the amorphous material layer below the first spacer kept; performing wet etching using an etchant solution that is isotropic to the amorphous material layer and whose etch rate to the amorphous material layer is greater than or substantially equal to the etch rate to the {100} and {110} surfaces of the substrate material but is far greater than the etch rate to the {111} surface of the substrate material, thus removing the amorphous material layer below the first spacer, such that the substrate material below the amorphous material layer is exposed to the solution and is etched thereby, and in the end, forming a Sigma shaped recess that extends to the nearby region below the gate stack; and epitaxially forming SiGe in the Sigma shaped recess.