Referring to FIG. 1, in operation 109 a passivation layer is deposited over the gate and exposed portion of the donor-supply layer. The passivation layer 213 is shown in FIG. 5 deposited around gate 211 and over portions of the donor-supply layer 205. The passivation layer 213 may include one or more layers of dielectric material. The dielectric material may be silicon nitride, silicon oxide, silicon oxynitride, carbon doped silicon oxide, carbon doped silicon nitride or carbon doped silicon oxynitride deposited using a CVD process. For example a low pressure CVD (LPCVD) at between about 600 degree Celsius and about 800 degrees Celsius may be used to deposit 300 angstrom to about 4000 angstrom of silicon nitride. In another example, a plasma enhanced CVD (PECVD) process may be used at 200 degrees Celsius to about 450 degrees Celsius to deposit about 300 angstroms to about 4000 angstroms of silicon nitride. In yet another example, a PECVD process is used to deposit silicon oxide. The dielectric materials may be combined to form the passivation layer 213. In one example, a 300 angstrom layer of silicon oxide is deposited over a 100 angstrom layer of silicon nitride to form the passivation layer 213. The passivation layer 213 may include other dielectric materials such as zinc oxide, zirconium oxide, hafnium oxide or titanium oxide. These other dielectric material may also be deposited using CVD processes.

The passivation layer 213 is between about 300 angstrom to about 4000 angstroms. The thickness of the passivation layer 213 affects the minimum distance between the source contact and the gate. Because in this process the gate is formed before the source and drain, the present disclosure provides a “gate first” process.