A method for forming a semiconductor structure is provided. The method includes patterning a semiconductor substrate to form a semiconductor fin, forming a source/drain structure on the semiconductor fin, forming an interfacial layer on the semiconductor fin, treating the interfacial layer with fluorine, forming a ferroelectric gate dielectric layer on the interfacial layer, treating the ferroelectric gate dielectric layer with fluorine, and forming a gate electrode layer on the ferroelectric gate dielectric layer.