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 degrees C while optimizing capacitance equivalent thickness (< 1.3 nm) at low leakage [J(1 V)< 10(-7) A/cm(2)]. (C) 2007 American Institute of Physics.