A mask including a transparent substrate, a semi-transparent layer and a film layer is provided. The transparent substrate at least has a first region, a second region and a third region. The semi-transparent layer covers the second region and the third region of the transparent substrate and exposes the first region. The film layer covers the halftone layer disposed at the third region, to make the transmittance of the third region lower than that of the second region. The halftone layer and the film can be made of phase shift layers, to form a phase shift mask. Besides, several fabrication methods of the mask are also disclosed to form the above-mentioned mask.