Approaching the limits of dielectric breakdown for SiO2 films deposited by plasma-enhanced atomic layer deposition

This study explores the ultimate limit in dielectric breakdown of SiO2 thin films deposited by gas-phase, plasma-enhanced atomic layer deposition. Thickness-dependent breakdown behaviors similar to conventional, thermally grown SiO2 thin films were observed for the first time on ALD films, where the dominant breakdown mechanisms were impact ionization, trap creation and anode hole injection, respectively. By suppressing these mechanisms, we show a reversible degradation in SiO2 after the onset of Fowler–Nordheim tunneling before permanent dielectric damage occurs. The reversible window was only observable in films thinner than 10 nm. The SiO2 thin films ultimately reached irreversible breakdown at a field strength of 2.7 V nm−1, where Si–O bonds were destroyed due to impact ionization and accelerated electrons.