Enhanced Dielectric Constant of HfO{sub}2 and Al{sub}2O{sub}3 Thin-Films with Silver Nanoparticles

摘要

Through an electron beam evaporation process, silver nanoparticles (Ag-nps) were introduced into dielectric thin-films. Silver incorporation into the oxide films resulted in a distribution of insulating Ag-nps at a density of ～10{sup}12 particles/cm{sup}2. For these samples, an enhancement of about two fold in dielectric constant was observed in both Al{sub}2O{sub}3 and HfO{sub}2. We attribute the dielectric constant enhancement to the polarizability of metallic nanoparticles. The dipole moment of the Ag-nps increased the stack dielectric constant in a frequency dependent manner. Because of the inherent relaxation frequency of the Ag-np dipoles and space-charge polarization, the dielectric constant was more strongly enhanced at lower frequencies (down to 100 Hz) relative to higher frequencies (up to 1 MHz). Gate leakage currents remained comparable between the control and nanocomposite samples. The Ag-nps also produced a memory effect. Potential applications of these Ag-np based films in CMOS devices are discussed.