Nitrogen incorporation engineering and electrical properties of high-k gate dielectric (HfO2 and Al2O3) films on Si(100) substrate

摘要

Pt/HfO2, HfO2-Al2O3, or Al2O3-HfO2-Al2O3/p-type Si (100) metal oxide semiconductor capacitors, which were fabricated using an atomic-layer-deposition technique, were post-deposition annealed under a NH3 atmosphere in order to investigate the nitrogen incorporation behavior along with their influences on the electrical properties. X-ray photoelectron spectroscopy showed that the binding energy of Hf 4f peak shifts to the lower values with increasing PDA temperature due to the formation of Hf-N bonds. An amorphous Al2O3 interface layer suppressed N diffusion into the Si substrate. The rapid thermally annealed HfO2-Al2O3 film at 800degreesC for 30 s, which contained approximately 20 at. % N in the HfO2 layer, showed a flat-band voltage shift of similar to30 mV (corresponding to a negative fixed charge similar to1.6 x 10(11) cm(-2)), a leakage current density of -4.7 x 10(-10) A/cm(2) at -1 V, a hysteresis voltage <20mV, excellent charge-to-breakdown characteristics and the lowest surface roughness. The single layer HfO2 film did not demonstrate good electrical properties due to excessive N diffusion into the Si substrate. A thin Al2O3 capping layer deteriorates the surface morphology and electrical properties of the HfO2-Al2O3 bilayer. (C) 2004 American Vacuum Society.