Patent ID: 8647953

Claim:
A method for fabricating a metal oxide semiconductor (MOS) device, comprising: forming two recesses in a substrate; performing a first epitaxy growth process, so as to form a first semiconductor compound layer in each of the recesses; and performing a second epitaxy growth process with an epitaxial temperature lower than 700, so as to form a cap layer on each of the first semiconductor compound layers, each of the cap layers comprising a second semiconductor compound layer that protrudes from a surface of the substrate, wherein the first semiconductor compound layers and the second semiconductor compound layers are composed of a first Group IV element and a second Group IV element that is a nonsilicon element, and a content of the second Group IV element in the second semiconductor compound layers is less than a content of the second Group IV element in the first semiconductor compound layers, and an included angle between a top surface of each of the second semiconductor compound layers and the surface of the substrate is less than 40°.