A method for fabricating a semiconductor structure includes forming a plurality of first fin structures in a peripheral region of a substrate and a plurality of second fin structures in a core region of the substrate, forming a first dummy gate structure including a first dummy oxide layer and a first dummy gate electrode layer on each first fin structure and a second dummy gate structure including a second dummy oxide layer and a second dummy gate electrode layer on each second fin structure. The method further includes removing each first dummy gate structure together with each second dummy gate electrode layer, forming a first gate oxide layer on the exposed portion of each first fin structure, and then removing each second dummy gate oxide layer. The method further includes forming a first gate structure on each first fin structure and a second gate structure on each second fin structure.