Structural and electrical characteristics of RF-sputtered HfO2 high-k based MOS capacitors

The HfO2 high-k thin films have been deposited on p-type (1 0 0) silicon wafer using RF magnetron sputtering technique. The XRD, AFM and Ellipsometric characterizations have been performed for crystal structure, surface morphology and thickness measurements respectively. The monoclinic structured, smooth surface HfO2 thin films with 9.45 nm thickness have been used for Al/HfO2/p-Si metal–oxide–semiconductor (MOS) structures fabrication. The fabricated Al/HfO2/Si structure have been used for extracting electrical properties viz dielectric constant, EOT, barrier height, doping concentration and interface trap density through capacitance voltage and current–voltage measurements. The dielectric constant, EOT, barrier height, effective charge carriers, interface trap density and leakage current density are determined are 22.47, 1.64 nm, 1.28 eV, 0.93 × 1010, 9.25 × 1011 cm−2 eV−1 and 9.12 × 10−6 A/cm2 respectively for annealed HfO2 thin films.

Research highlights
► In this study we have deposited and analyzed the HfO2 as the high-k dielectric for MOS capacitor.
► The AFM studies prove the deposited films are very much smooth and this smoothness improves on annealing.
► It is observed that flat-band voltage (VFB) shifts towards negative potential due to positive trap charge.
► The annealed HfO2 films show very low leakage current of 9.12 × 10−6 A/cm2 at 1V.