Abstract: A semiconductor structure including a substrate and protection structures is provided. The substrate includes a die region. The die region includes corner regions. The protection structures are located in the corner region. Each of the protection structures has a square top-view pattern. The square top-view patterns located in the same corner region have various sizes.

Abstract: A fabricating method of a middle voltage transistor includes providing a substrate. A gate predetermined region is defined on the substrate. Next, a mask layer is formed to cover only part of the gate predetermined region. Then, a first ion implantation process is performed to implant dopants into the substrate at two sides of the mask layer to form two first lightly doping regions. After removing the mask layer, a gate is formed to overlap the entirety gate predetermined region. Subsequently, two second lightly doping regions respectively formed within one of the first lightly doping regions. Next, two source/drain doping regions are respectively formed within one of the second lightly doping regions. Finally, two silicide layers are formed to respectively cover one of the source/drain doping regions.