An MOS transistor formed on a heavily doped substrate is described. Metal gates are used in low temperature processing to prevent doping from the substrate from diffusing into the channel region of the transistor.A method for fabricating a field-effect transistor with a gate completely wrapping around a channel region is described. Ion implantation is used to make the oxide beneath the channel region of the transistor more etchable, thereby allowing the oxide to be removed below the channel region. Atomic layer deposition is used to form a gate dielectric and a metal gate entirely around the channel region once the oxide is removed below the channel region.