Stabilization of higher-$κ$ tetragonal $HfO2$ by $SiO2$ admixture enabling thermally stable metal-insulator-metal capacitors

The authors report the relationship between $HfO2$ crystalline phase and the resulting electrical properties. Crystallization of amorphous $HfO2$ into the monoclinic phase led to a significant increase in leakage current and formation of local defects. Admixture of 10% $SiO2$ avoided formation of these defects by stabilization of the tetragonal phase, and concurrently increased the permittivity to 35. This understanding enabled fabrication of crystalline $HfO2$ based metal-insulator-metal capacitors able to withstand a thermal budget of $1000°C$ while optimizing capacitance equivalent thickness $(<1.3nm)$ at low leakage $[J(1V)<10−7A∕cm2]$⁠.