Low-temperature oxidation of SiGe by liquid-phase deposition

Low-temperature silicon dioxide (SiO2) films were grown on silicon germanium (SiGe) surfaces using the liquid-phase deposition (LPD) method. The growth solutions of LPD-SiO2 are hydrofluorosilicic acid (H2SiF6) and boric acid (H3BO3). It was found that the growth rate increases with increasing temperature and concentration of H3BO3. The Auger electron spectroscopy profile shows that no pileup of Ge atoms occurs at the interface of SiO2/SiGe after the LPD-SiO2 growth. Al/LPD-SiO2/p-SiGe MOS capacitors were prepared to determine capacitance-voltage (C-V) and current-voltage (I-V) characteristics. In our experiments, a low leakage current density of 8.69 x 10-9 A/cm2 under a 2 MV/cm electric field was observed. Such a value is much smaller than those of plasma- and thermal-oxides as a result of no plasma damage and a lower growth temperature. Moreover, lower oxide charges and interface charge densities of 3.82 x 1010 cm-2 and 1.12 x 1011 eV-1 cm-2, respectively, were achieved in our LPD-SiO2 compared to direct photochemical-vapor-deposition-SiO2