Method for manufacturing FinFET

The invention discloses a method for manufacturing a FinFET. The method comprises the following steps: a) providing an SOI substrate which comprises a semiconductor substrate, a buried insulating layer on the semiconductor substrate and a Si layer on the buried insulating layer; b) etching the Si layer until the buried insulating layer is exposed so as to form a first fin for an NMOS transistor and a second fin for a PMOS transistor; c) forming a reaction layer only covering the second fin, wherein the reaction layer containing Ge; and d) executing a Ge condensation process so that Ge is diffused to the second fin from the reaction layer. According to the method for manufacturing the FinFET of the present invention, Ge can be added into the second fin for the PMOS transistor through the Ge condensation process without producing any influence on the first fin for the NMOS transistor, and the migration rate of the PMOS transistor is improved.