Structure and property changes of ZrO2/Al2O3/ZrO2 laminate induced by low-temperature NH3 annealing applicable to metal–insulator–metal capacitor

Phase transformation and morphology evolution of ZrO2/Al2O3/ZrO2 laminate induced by the post-deposition NH3 annealing at 480°C were studied and the effect on the electrical property of the TiN/ZrO2/Al2O3/ZrO2/TiN capacitor module was evaluated in dynamic random access memory cell. Experimental results indicated N could indeed be incorporated into the dielectric laminate by the low-temperature NH3 annealing, resulting in tetragonal-to-cubic phase transformation and small crystallites in the ZrO2 layers. The C residue and Cl impurity in the ZrO2/Al2O3/ZrO2 laminate, which derived from the dielectric film formation and capping TiN layer deposition, respectively, could also be reduced by the nitridation process. As a result of the better surface morphology and less impurity content, lower dielectric leakage current and longer reliability lifetime were observed for the nitrided ZrO2/Al2O3/ZrO2 capacitor. This study demonstrates the low-temperature NH3 annealing on ZrO2/Al2O3/ZrO2 dielectric can be applicable to the metal–insulator–metal capacitor structure with nitride-based electrode, which brings advantages over mass production-wise property improvements and extends the practical applicability of the ZrO2/Al2O3/ZrO2 dielectric.