Total-Dose Radiation Response of HfLaO Films Prepared by Plasma Enhanced Atomic Layer Deposition

HfLaO and HfO₂ films were deposited by plasma enhanced atomic layer deposition (PEALD). PEALD makes in-situ plasma treatment possible, and the film growth temperature can be reduced. The films were characterized. High resolution transmission electron microscopy (HRTEM) indicated both films were amorphous. X-ray photoelectron spectroscopy (XPS) suggested that the interface layer was most likely composed of Hf-Si-O and La-Si-O. MIS capacitors with HfLaO and HfO₂ dielectrics were irradiated by gamma rays with the dose up to 2×10⁶ rad (Si). Electrical measurements indicated that the dielectrics showed relatively stable electrical properties. The equivalent oxide thicknesses (EOT) of HfLaO samples were calculated to be 0.9 nm. At a gate condition of |V_g-V_fb| = 1 V, the leakage current densities were 0.02 mA/cm². With the increasing of the radiation dose, the maximum oxide trap charge density and interface trap charge density for HfLaO samples were calculated to be 2.6×10⁶ cm^-2 and 1.2×10¹² cm^-2, respectively. The analysis of the IV curves suggested that the conduction mechanism in HfLaO samples is the Poole-Frenkel emission.