Substrate bias voltage influence on structural, electronic and dielectric properties of ZrO2 gate dielectrics

In this investigation, zirconium oxide films were deposited on silicon held at different substrate bias voltages from O(un-biased) to -150 V by reactive magnetron sputtering of zirconium target at an oxygen partial pressure of 6 × 10^-2 Pa. The influence of substrate bias voltage on the structural, optical properties of thin films and electronic properties like Capacitance-Voltage and Current -Voltage of the capacitors of the type AI/ZrO₂/p-Si were systematically studied. The structural transformation from orthorhombic to tetragonal phase has influences the dielectric constant of the films. The interfacial quality was improved upon substrate biasing and the leakage current density was decreased from 1.4 × 10^-7 to 2.9 × 10^-7 A/cm² at IV gate bias voltage (thickness of the oxide film 55 nm). The conduction mechanism was dominated by Schottky emission at lower electric fields and Pool-Frenkel mechanism at higher electric fields.