A method for making FinFETs and semiconductor structures formed therefrom is disclosed, comprising: providing a SiGe layer on a Si semiconductor substrate and a Si layer on the SiGe layer, wherein the lattice constant of the SiGe layer matches that of the substrate; patterning the Si layer and the SiGe layer to form a Fin structure; forming a gate stack on top and both sides of the Fin structure and a spacer surrounding the gate stack; removing a portion of the Si layer which is outside the spacer with the spacer as a mask, while keeping a portion of the Si layer which is inside the spacer; removing a portion of the SiGe layer which is kept after the patterning, to form a void; forming an insulator in the void; and epitaxially growing stressed source and drain regions on both sides of the Fin structure and the insulator.