Ultrathin HfO₂ gate dielectrics on partially strain compensated SiGeC/Si heterostructure

Ultrathin HfO₂ gate dielectrics have been deposited on strain-compensated Si_0.69Ge_0.3C_0.01 layers by rf magnetron sputtering. X-ray diffraction spectra show the films to be polycrystalline having both monoclinic and tetragonal phases. The formation of an interfacial layer has been observed by high-resolution transmission electron microscopy. Secondary ion mass spectroscopy and Auger electron spectroscopy analyses show the formation of an amorphous Hf-silicate interfacial layer between the deposited oxide and SiGeC films. The average concentration of Ge at the interfacial layer is found to be 2-3 at%. The leakage current density of HfO₂ gate dielectrics is found to be several orders of magnitude lower than that reported for thermal SiO₂ with the same equivalent thickness.