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

Abstract

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 (3.5×10−4 A/cm2). 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 °C, which represents a significantly improved performance of larger dielectric constant (13.34) and lower leakage current density (8.19×10−5 A/cm2).