Ferroelectric properties of HfO2 interlayers in SOI and SOS pseudo-MOSFETs

Formation of a multi-crystalline HfO2 film, containing ferroelectric phase OII (Pmn21), after a high-temperature annealing at 1100°C, was experimentally observed for the first time in SOS structures obtained by a hydrogen transfer of silicon layer on Si or c-sapphire substrates respectively. PEALD HfO2 interlayers with the thickness of 20 nm were deposited on silicon before bonding to reduce the defects and the magnitude of their charge at the SOI and SOS interfaces. SOS pseudo-MOS transistors demonstrate normal drain-gate characteristics with the charge carrier mobility as in bulk silicon and a smaller positive charge (≤ 1.2×10¹² cm⁻²). Moreover, a stable ferroelectric hysteresis with ΔVG ∼600 V promising for the embedded memory formation and they extend the functionality of logic circuits.