A fin shaped structure and a method of forming the same, wherein the method includes forming a fin structure on a substrate. Next, an insulation layer is formed on the substrate and surrounds the fin structure, wherein the insulation layer covers a bottom portion of the fin structure to expose an exposed portion of the fin structure protruded from the insulation layer. Then, a buffer layer is formed on the fin structure. Following this, a threshold voltage implantation process is performed to penetrate through the buffer layer after forming the insulation layer, to form a first doped region on the exposed portion of the fin structure.