A series of high dielectric material Er2O3 thin films with different thicknesses were deposited on p-type Si (100) substrate by pulse laser deposition at different temperatures. Phase structures of the films were determined by means of X-ray diffraction (XRD) and high resolution transmission electron microscopy (HRTEM). Leakage current density was measured with an HP4142B semiconductor parameter analyzer. The XRD and HRTEM results reveal that Er2O3 thin films deposited below 400 °C are amorphous, while films deposited from 400 to 840 ° are well crystallized with (111)-preferential crystallographic orientation. I-V curves show that, for ultrathin crystalline Er2O3 films, the leakage current density increases by almost one order of magnitude from 6.20 × 10 -5 to 6.56 × 10-4 A/cm2, when the film thickness decreases by only 1.9 nm from 5.7 to 3.8 nm. However the leakage current density of ultrathin amorphous Er2O3 films with a thickness of 3.8 nm is only 1.73 × 10-5 A/cm2. Finally, analysis of leakage current density showed that leakage of ultrathin Er2O3 films at high field is mainly caused by Fowler-Nordheim tunneling, and the large leakage of ultrathin crystalline Er2O3 films could arise from impurity defects at the grain boundary.
Xinjiang Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Urumqi 830011, China;Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China;Graduate University, Chinese Academy of Sciences, Beijing 100049, China
Wu, Deqi,Yao, Jincheng,Zhao, Hongsheng,et al. Leakage current mechanisms of ultrathin high-k Er2O3 gate dielectric film[J]. Journal of Semiconductors,2009,30(10):21-26.