Improved Dielectric Constant and LeakageCurrent of ZrO2-Based Metal-Insulator-Metal Capacitors by Si Doping

As the feature size of dynamic randomaccess memories (DRAM) continues to scale down, theshrunk storage capacitors have met essential challenges,namely, the insufficient capacitances and the excessiveleakage currents. In this article, the electrical propertiesof silicon-doped zirconia (ZrO2) films, with the goal ofimproving their properties for use as capacitor dielectricfor DRAM, were investigated. The results indicated thatthe introduction of an appropriate amount of Si canincrease the portion of the tetragonal crystal phase in ZrO(2)dielectric, thereby leading to an increase in the dielectricconstant by 26.8%. Even higher Si content leads to thedegradation of the crystal structure. Additionally, Si dopinglikely deepens the depth of defect energy levels in thedielectric, which may suppress the leakage current ofthe metal-insulator-metal (MIM) capacitors. Comparedwith the un-doped samples, the leakage current wasreduced by 60.2% at the operating voltage of 0.8 V. Theequivalent oxide thickness (EOT) was reduced by 17.5%at the standard leakage current density (<1x10(-7)A/cm(2)at 0.8 V). It demonstrated that the Si doping strategy caneffectively enhance the capacitance of capacitors andsuppress leakage current, thereby addressing the criticalissues associated with ZrO2-based MIM capacitors.