Ferroelectric HfO2 formation by annealing of a HfO2/Hf/HfO2/Si(100) stacked structure

Abstract

In this research, ferroelectric characteristics of HfO2 formed by annealing of a HfO2/Hf/HfO2/Si(100) stacked structure were investigated. It was found that the HfO2/Hf/HfO2 stacked structure enhanced the formation of a metastable orthorhombic phase HfO2 on Si(100) substrate by a post-deposition annealing (PDA) process at a low-temperature of 600 °C. The remnant polarization (2Pr) of 20 μC cm−2 was obtained, which is larger than the 14 μC cm−2 observed in the diode without a 1 nm thick Hf interlayer. However, the C–V characteristics with ferroelectric hysteresis was not obtained because its coercive field (2Ec) was as high as 9.6 MV cm−1. On the other hand, the diode with a post-metallization annealing process induced the memory window of 0.9 V at the sweep range from −4 to 4 V in spite of smaller Pr in its P–V characteristic than that of the diode with PDA process.