Low-voltage operation and high endurance of 5-nm ferroelectric Hf0.5Zr0.5O2 capacitors

Abstract

In this letter, the ferroelectric (FE) properties of 5-nm-thick Hf0.5Zr0.5O2 (HZO) films deposited by atomic layer deposition have been investigated. By reducing the HZO film thickness to 5 nm, low-voltage operation (1.0 V) of the HZO-based capacitor was achieved while maintaining a remnant polarization (Pr) of about 10 μC/cm2 (i.e., 2Pr of 20 μC/cm2). Meanwhile, in order to form an orthorhombic phase, which is responsible for FE properties, a rapid thermal annealing process was performed after TiN top electrode deposition. The FE properties were realized after low temperature annealing (450 °C for 1 min), making them compatible with the back-end of the line. In addition, the low operating voltage and the suppression of an additional monoclinic phase formation by stress-induced crystallization induced a robust endurance (>1010 cycles at 1.2 V) of the 5-nm-thick HZO sample.