Low Leakage in High-k Perovskite Gate Oxide SrHfO3

Abstract

Reducing the leakage current through the gate oxide is becoming increasingly important for power consumption reduction as well as reliability in integrated circuits as the semiconducting devices continue to scale down. Here, this work reports on the high-k dielectric SrHfO3 (SHO) based devices with ultralow leakage current density via pulsed laser deposition (PLD). The ultralow current density is achieved by optimizing the growth conditions and the associated structural properties. In the optimized conditions, the dielectric properties of the 50-nm-thick SHO capacitors are measured: high dielectric constant (κ = 32), low leakage current density (<10−8 A cm−2 at 2 MV cm−1), and large breakdown field (EBD > 4 MV cm−1). The surprisingly low leakage current density of SHO is ascribed to the large bandgap (≈6 eV), the large conduction band offset (CB offset > 3 eV) with respect to the semiconductor, and the low density of defect states inside the bandgap. The optimized SHO dielectric with high dielectric constant and ultralow leakage current density is proposed for future low-power consumption devices based on Si as well as perovskite oxide semiconductors. © 2023 The Authors. Advanced Electronic Materials published by Wiley-VCH GmbH.