Improved Characteristics of Ultrathin CeO₂ by Using Postnitridation Annealing

This work demonstrates the improved characteristics of an ultrathin CeO₂ dielectric by using the post-N₂O plasma treatment with additional rapid thermal N₂ annealing. The CeO₂ after the treatment exhibits superior characteristics such as a small effective oxide thickness (∼2.25 nm), a low leakage current (5.4 × 10 ^-4 A/cm²), a high breakdown electric field (-24 MV/cm), a long projected 10 yr lifetime (-12 MV/cm), a small capacitance-voltage hysteresis (25 mV), and a high barrier height for Frenkel-Poole emission (0.55 eV). These good properties are attributed to the nitrogen incorporation into the dielectric to eliminate the traps after annealing. The postnitridation annealing appears to be a very useful treatment for future ultrathin metal-oxide gate dielectrics.