Atomic-layer-deposited Al2O3-HfO2 laminated and sandwiched dielectrics for metal–insulator–metal capacitors

Abstract

Metal–insulator–metal (MIM) capacitors with atomic-layer-deposited Al2O3–HfO2 laminated and sandwiched dielectrics have been fabricated and electrically compared for analog circuit applications. The experimental results indicate that the laminated dielectrics exhibit much better leakage and breakdown characteristics than the sandwiched ones while maintaining higher capacitance densities and acceptable voltage linearity. In respect of the 1 nm Al2O3 and 10 nm HfO2 laminated dielectric, the resulting capacitor offers an extremely low leakage current of 2.4 × 10−9 A cm−2 at 8 V and a breakdown electric field of ∼3.3 MV cm−1 at 125 °C together with a capacitance density of ∼3.1 fF µm−2 and voltage coefficients of capacitance of 100 ppm V−2 and −80 ppm V−1 at 100 kHz. The superiority of the laminated dielectrics correlates with inhibition of HfO2 crystallization, discontinuity of the grain boundary channels from the top to the bottom and changes of the dielectric electronic properties due to the bonding and polarization effects at the multi-interfaces.