A fin field-effect transistor (“FinFET”) semiconductor device and method of forming the same. In one example, a semiconductor fin is formed over a semiconductor substrate. A conformal dielectric layer is formed on a top and side surfaces of the fin. A doped semiconductor layer is formed over the conformal dielectric layer, the doped semiconductor layer including a dopant. The doped semiconductor layer is heated thereby driving the dopant through the conformal dielectric layer and forming a doped region of the fin.