A method of manufacturing a FinFET semiconductor device is provided, wherein the semiconductor fins are formed in a parallel arrangement which intersects the gates arranged in parallel. The polycrystalline silicon layer is deposited and then converted into a single crystal silicon layer such that the single crystal silicon layer and the semiconductor fins are integrated in essence, i.e., the source/drain region in the semiconductor fins is raised and the top area of the semiconductor fins is extended. Subsequently, the single crystal silicon layer above the top of the semiconductor fins is converted into a metal silicide so as to form a source/drain region contact. The source/drain region contact in the present invention has a larger area than that in a conventional FinFET, which decreases the contact resistance and facilitates the formation of a self-aligned metal plug in the follow-up process.