Atomic Layer Deposition of Boron‐Doped Al₂O₃ Dielectric Films

Abstract This paper presents preparation of boron‐doped Al₂O₃ thin films by atomic layer deposition (ALD) using phenylboronic acid (PBA) and trimethylaluminum (TMA) as precursors. Deposition temperatures of 160–300 °C are studied, giving a maximum growth per cycle (GPC) of 0.77 Å at 200 °C. Field emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM) are used to study the surface morphology and roughness of the films. Attenuated total reflectance Fourier transform infrared spectroscopy (ATR‐FTIR), Time‐of‐flight elastic recoil detection analysis (ToF‐ERDA), and X‐ray photoelectron spectroscopy (XPS) are used to study the composition of the films. An annealing process is carried out at 450 °C for 1 h to investigate its effect on the elemental composition and electrical properties of the boron‐doped Al₂O₃ thin films. The boron‐doped Al₂O₃ 70 nm thick film deposited at 200 °C has a boron content of 3.7 at.% with low leakage current density (10⁻⁹ to 10⁻⁶ A cm⁻²) when the film thickness is 70 nm. The dielectric constant of this boron doped Al₂O₃ film is 5.18.