Stabilization of higher-k tetragonal HfO/sub 2/ by SiO/sub 2/ admixture enabling thermally stable metal-insulator-metal capacitors

Abstract

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 1.3 nm at low leakage J 1 V 10−7 A/cm2 .