Al2O3 blocking layer inserted ZrO2 Metal-Insulator-Metal capacitor for the improved electrical and interfacial properties

Abstract

Atomic layer deposition with O3 reactant is widely used to deposit thin and conformal films in a ZrO2 based metal-insulator-metal (MIM) capacitor. Post-deposition annealing (PDA) improves the MIM capacitor's performances by crystallizing tetragonal ZrO2 with high dielectric constant but it inevitably causes formation of excessive TiN/ZrO2 interface. Oxygen diffusion from ZrO2 to TiN bottom electrode oxidizes TiN to TiOx and TiOxNy during PDA, which increases the capacitance equivalent thickness of interlayer (CETint) and leakage current of the MIM capacitor. In this study, we inserted a Al2O3 thin film as the oxygen diffusion blocking layer (ODBL) between ZrO2 dielectric and bottom TiN electrode to improve the interfacial properties in TiN/ZrO2/TiN MIM capacitor. The angle-resolved X-ray photoelectron spectroscopy is employed to study the effects of Al2O3 OBDL on the chemical states of the interfacial layer in MIM capacitor, which confirmed that the Al2O3 ODBL inhibits the growth of TiN/ZrO2 interface. In addition, the electrical analysis of MIM capacitor showed that the CET of TiN/ZrO2 interface decreased from 0.493 to 0.209 nm and the leakage current highly decreased from 10−7 to 10−9 A/cm2 at 1 V although the dielectric constant slightly reduced from 35.1 to 30.7 with the insertion of Al2O3. This study offers a systematic investigation of interfacial layers in Al2O3 OBDL inserted ZrO2 MIM capacitor in the points of chemical and electrical characterization.