Electrical and Structural Characterization of HfO_2 MIM Capacitors

摘要

Hafnium oxide is a promising dielectric for future microelectronic applications. HfO_2 thin films (10-75nm) were deposited on Pt/SiO_2/Si and quartz substrates by Pulsed DC magnetron reactive sputtering. Top electrodes of Pt were formed by e-beam evaporation through an aperture mask on the HfO_2/Pt/SiO_2/Si samples to create MIM capacitors. Various process conditions (Ar/O_2 ratio, DC power, and deposition rate) and post-deposition annealing conditions (time and temperature) were investigated. The structure of the HfO_2 films was characterized by X-ray diffraction (XRD) and the roughness was measured by a profilometer. The electrical properties were characterized in terms of their relative permittivity (ε_r(T) and ε_r(f)), and leakage behavior (I-V and I-t). The electrical measurements were performed over a temperature range from -5 to 200 °C. For the best samples, the relative permittivity of HfO_2 was found to be ～27 after anneal and increased by 0.027%/°C with increasing temperature over the measured temperature range. At 25 °C, leakage current density was below 10~(-8) A/cm~2 at 1 volt. The optical bandgap was measured to be 5.4eV after anneal.