Abstract
Phase transformation and morphology evolution of ZrO 2 /Al 2 O 3 /ZrO 2 laminate induced by the post-deposition NH 3 annealing at 480 °C were studied and the effect on the electrical property of the TiN/ZrO 2 /Al 2 O 3 /ZrO 2 /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 NH 3 annealing, resulting in tetragonal-to-cubic phase transformation and small crystallites in the ZrO 2 layers. The C residue and Cl impurity in the ZrO 2 /Al 2 O 3 /ZrO 2 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 ZrO 2 /Al 2 O 3 /ZrO 2 capacitor. This study demonstrates the low-temperature NH 3 annealing on ZrO 2 /Al 2 O 3 /ZrO 2 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 ZrO 2 /Al 2 O 3 /ZrO 2 dielectric. © 2010 Elsevier B.V.