Hydrogen shuttling near Hf-defect complexes in Si∕SiO2∕HfO2 structures

Abstract

We propose that a defect complex comprising a suboxide Hf–Si bond and an interfacial dangling bond is responsible for the stress-induced buildup of interface traps in Si∕SiO2∕HfO2 capacitors. With the aid of first-principles calculations, we show that these defects possess a symmetric double-well energy minimum with a moderate intervening barrier. The calculated activation energies suggest a relatively easy hopping of H atoms between the two energy minima (a field-aided shuttling mechanism). This mechanism can explain the experimentally measured oscillations of interface-trap densities during switched-bias conditions following x-ray irradiation or constant-voltage stress.