Improved dielectric properties of La2O3-ZrO2 bilayer films for novel gate dielectrics

La2O3 film with large theoretical k value and ZrO2 film with large theoretical band gap are selected to fabricate bilayer composite dielectric films by magnetron sputtering. La2O3-ZrO2 bilayer films combine the advantages of both La2O3 and ZrO2 films. We demonstrate that Pt/La2O3-ZrO2/Si MOS capacitor is more favorable for transistors than Pt/ZrO2-La2O3/Si MOS capacitor, featuring for a larger dielectric constant (12.37) and a lower leakage current (3.5 x 10(-4) A/cm(2)). Besides, our results indicate that optimal sublayer thicknesses of La2O3 and ZrO2 film are both 10 nm as well as the optimal temperature is 500 degrees C, which represents a significantly improved performance of larger dielectric constant (13.34) and lower leakage current density (8.19 x 10(-5) A/cm(2)).