A method for manufacturing a fin structure. The method includes: forming a first semiconductor layer and a second semiconductor layer sequentially on a substrate; patterning the second and first semiconductor layers to form an initial fin; selectively etching the first semiconductor layer of the initial fin so that the first semiconductor layer has a lateral recess; forming an isolation layer having a portion that fills the lateral recess, wherein the isolation layer, except the portion that fills the lateral recess, has a top surface lower than a top surface of the first semiconductor layer but higher than a bottom surface of the first semiconductor layer, and thus defines a fin above the isolation layer; and forming a gate stack intersecting the fin on the isolation layer.