Controllable nitrogen incorporation in HfO2 films by modulating capacitively-combined inductively-coupled plasmas

Capacitively-combined inductively-coupled nitrogen (N) plasma discharges were investigated to nitridize ultrathin HfO2 films (5 nm) for leakage improvement. The result of x-ray photoelectron spectroscopy analysis shows N incorporation into the HfO2 films. In terms of the plasma chemical and surface processes, nitridation samples show great improvements in surface structure and the leakage current property (it decreases from 4.6 x 10(-4) to 2.1 x 10(-7) A cm(-2)), while the leakage current is independent of the morphology. The radical concentration of N atoms increases with inductively-coupled plasma (ICP) power. This kind of capacitively-coupled plasma (CCP) combined with ICP modes is capable of modulating the electron energy probability functions (EEPFs) based on the power levels of ICP and can facilitate tuning of the N-2 discharge dissociation characteristics. By modulating the EEPFs depending on the power levels of CCP and ICP, the radical concentration of the N atom increases by the electron-neutrals collision dependence on the high-energy electron, resulting in more N atoms incorporated in HfO2 films. The lower effective electron temperature and ion energy were obtained with ICP power, causing less film surface damage. Therefore, N atoms possess intrinsic effects that drastically reduce the electron leakage current through HfO2 dielectrics by deactivating the oxygen vacancy related gap states.