Enhanced electrical properties of Nb-doped a-HfO2 dielectric films for MIM capacitors

摘要

We report enhanced electrical properties of metal–insulator–metal (MIM) capacitors consisting of Al (100 nm)/Nb-doped a -HfOsub2/sub (～30 nm)/Pt (100 nm) on a p-type silicon wafer, where Nb-doped amorphous HfOsub2/sub ( a -HfOsub2/sub) layers were deposited by radio frequency magnetron sputtering in various low oxygen partial pressures at room temperature. Polycrystalline HfOsub2/sub targets with three different Nb contents of 0 mol.?%, 6 mol.?%, and 10 mol.?% were used in this study. Compared with the leakage current of the undoped a -HfOsub2/sub film (～1.1 × 10sup?8/sup A cmsup?2/sup at 1 V), greatly reduced leakage currents (～3.7 × 10sup?10/sup A cmsup?2/sup at 1 V) with no significant alteration in the dielectric constants (～22) were obtainable from the MIM samples composed of Nb-doped a -HfOsub2/sub films, which is attributable to the suppression of oxygen vacancy formation based on the XPS analysis results. The Nb-doped a -HfOsub2/sub dielectric thin films also exhibited improved voltage nonlinearity compared to undoped HfOsub2/sub. These results indicate that Nb-doped a -HfOsub2/sub has potential application as a high-κ dielectric material in MIM capacitors.