A method of manufacturing a semiconductor structure is disclosed, which includes providing a substrate comprising a bottom surface and a growth surface opposite to the bottom surface; forming a buffer layer comprising a first surface which is not a C-plane substantially parallel with the bottom surface on the growth surface; forming a semiconductor structure on the buffer layer; forming at least one cavity in the buffer layer; extending the cavity along a main extending direction; separating the substrate and the semiconductor structure; wherein the main extending direction is substantially not parallel with the normal direction of the first surface.