An asymmetric fin field-effect transistor (FinFET) in a memory device, a method for fabricating the FinFET and a semiconductor device are disclosed. In the provided FinFET and method, each of the active areas comprises a fin, a length of a first end of the fin on a first side of the active area and covered by the word line being different from a length of a second end of the fin on a second side of the active area and covered by the word line. For this reason, the present invention allows reduced process difficulty. In addition, the different lengths of the word lines can induce a weaker unidirectional electric field which suffers from much less current leakage, compared to a bidirectional electric field created in word lines with equal such length.