Atomic Layer Deposition of Boron‐Doped Al2O3 Dielectric Films

• Published in: Advanced materials interfaces Vol. 10; no. 18
• Main Authors: Li, Xinzhi, Vehkamäki, Marko, Chundak, Mykhailo, Mizohata, Kenichiro, Vihervaara, Anton, Leskelä, Markku, Putkonen, Matti, Ritala, Mikko
• Format: Journal Article
• Language: English
• Published: Weinheim John Wiley & Sons, Inc 01.06.2023; Wiley-VCH
• Subjects: Aluminum oxide; atomic layer deposition; Atomic layer epitaxy; Boron; Composition; dielectric constant; doped Al2O3; Elastic analysis; Electrical properties; Field emission microscopy; Film thickness; Flight operations; Fourier transforms; Infrared analysis; Infrared spectroscopy; Leakage current; Microscopy; Photoelectrons; Spectrum analysis; Thin films; United States > US
• ISSN: 2196-7350; 2196-7350
• DOI: 10.1002/admi.202300173

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. In this work, boron doped Al2O3 films are deposited from two precursors, phenylboronic acid (PBA) and trimethylaluminum (TMA). AlCl3 is used as an alternative aluminum precursor in reference experiments. The film growth process is well controllable. In addition, the dielectric constant and leakage property of the boron doped Al2O3 films are also investigated. The boron doped Al2O3 can be used as a low‐k spacer material.