A method of manufacturing a semiconductor device is provided, including: forming a first conductive type lightly doped region in the epitaxial layer; forming a first conductive type heavily doped region and a second conductive type heavily doped region in the epitaxial layer on the first conductive type lightly doped region, in which the neighboring first conductive type heavily doped regions are spaced apart by the second conductive type heavily doped region; disposing the mask on the second conductive type heavily doped region; disposing a spacer on a sidewall of the mask; doping a first conductive type dopant in the first conductive type lightly doped region to form an anti-breakdown region; removing the mask and forming a trench extending into the second conductive type heavily doped region, first conductive type lightly doped region and the epitaxial layer; and removing the spacer.