This work investigated high permittivity hafnium based dielectric films for use in future generation metal oxide semiconductor field-effect transistor (MOSFET) technologies. For the sub- 100 nm MOS structure, the conventional Si02 gate dielectric required is becoming too thin (
Two deposition processes were used for investigating hafnium oxide: A traditional reactive sputtering process using a hafnium target and oxygen along with a metal oxidation process in which hafnium metal was deposited and subsequently oxidized in a rapid thermal processor. The films and their interfacial layers were studied using transmission electron microscopy and Rutherford backscattering. Suppression of the interfacial layers was attempted by utilizing various pre-deposition cleaning processes, nitrogen incorporation, and multiple annealing conditions. Statistical analysis was performed on many film properties including: thickness and refractive index by ellipsometry, equivalent oxide thickness (EOT), relative permittivity (sr), total charge density (Nss) via capacitance-voltage analysis (C-V), oxide charge density (Qox) and interface trap charge density (DiT) from surface charge analysis, and breakdown strength vi and leakage current density from current-voltage analysis (I-V). Hafnium oxide was successfully integrated into an RIT sub-micron NMOS process, and operational 0.5 um transistors were fabricated and tested
