High-density energy storage in Si-doped hafnium oxide thin films on area-enhanced substrates

Abstract

Capacitors based on 10 nm antiferroelectric silicon-doped hafnium oxide (Si:HfO2) thin films are investigated in terms of energy storage efficiency, cycling endurance, and reliability. Atomic layer deposition (ALD) on an area-enhanced substrate with large-scale arrays of deep-trench structures is used to significantly increase the energy density, yielding a value of 450 μJ/cm2 and an energy storage efficiency of 67% at a voltage of 3 V. High breakdown fields are obtained, and the reliability measurement indicates that more than 90% of the devices survive three years when subjected to an operating voltage of 3 V. The film stoichiometry is optimized in terms of energy storage properties to achieve an antiferroelectric-like hysteresis loop with low fatigue during electric field cycling and uniform electrical characteristics throughout the 300 mm wafer. Si:HfO2 is a promising material for novel integrated energy storage applications, as it combines CMOS compatible manufacturing, high scalability, and conformal deposition using ALD.