X-ray reflectometry and spectroscopic ellipsometry characterization of Al₂O₃ atomic layer deposition on HF-last and NH₃ plasma pretreatment Si substrates

Abstract

Al 2 O 3 films are grown by atomic layer deposition (ALD) using trimethylaluminum and water as precursors on HF-last and NH 3 plasma pretreatment Si substrates. The thickness, surface roughness, and density of Al 2 O 3 films as well as the nature of their interlayers with Si substrates are characterized by x-ray reflectivity and spectroscopic ellipsometry techniques. The growth rates of Al 2 O 3 films are 1.1 Å/cycle and 1.3 Å/cycle, respectively, on HF-last and NH 3 -plasma-nitrided surfaces. Al 2 O 3 layer densities are rather independent of the number of growth cycles in all cases. The interfacial film thickness increases with the number of ALD cycles when deposited on an HF-last Si substrate. However, because SiO x N y inhibits oxygen diffusion, the interfacial film thickness is independent of the number of ALD cycles on the nitrided Si substrate.

Origin of the Double Polarization Mechanism in Aluminum-Oxide-passivated Quasi-free-standing Epitaxial Graphene on 6H-SiC(0001)

“…Comparing the density profiles of a-Al 2 O 3 on QFS-graphene/6H-SiC(0001) (Figure B) and on Si (Figure A), one learns that regardless of the deposition protocol, the nature of the density changes is entirely different. In the case of a-Al 2 O 3 on silicon, the oxide density is primarily constant and close to the value expected for amorphous Al 2 O 3 deposited at 300 °C (2.90–3.15 g/cm 3 ) . In the case of a-Al 2 O 3 on QFS-graphene/6H-SiC(0001), a systematic increase in the oxide density is noticeable as the layer thickness increases.…”

“…In the case of a-Al 2 O 3 on silicon, the oxide density is primarily constant and close to the value expected for amorphous Al 2 O 3 deposited at 300 °C (2.90−3.15 g/cm 3 ). 45 In the case of a-Al 2 O 3 on QFSgraphene/6H-SiC(0001), a systematic increase in the oxide density is noticeable as the layer thickness increases. This result directly confirms the previous literature reports on the discontinuous growth of a-Al 2 O 3 on graphene on SiC.…”

“…Each of these values is within the range of the expected density of a-Al 2 O 3 on silicon deposited by ALD (from 2.50 g/cm 3 for roomtemperature ALD to 3.15 g/cm 3 for ALD at 300 °C). 44,45 Further to this, annealing in O 2 plasma also significantly affects the density at the surface of the oxide −3.15 g/cm 3 for the T-ALD process with plasma annealing compared to 4.02 g/cm 3 for the purely thermal process. The decrease in the density value is most likely due to the cleaning of the oxide surface from the nonadsorbed particles.…”

Multi-scale modelling and experimental analysis of ALD alumina

“…The substrate pre-treatment by NH3 or NH3 plasma has shown comparable effects on the reduction of the induction period and the interfacial layer formation (Brewer et al, 2004) (Lu et al, 2007). Brewer et al have used a thermal N2-NH3 pretreatment prior to deposition and have shown an increase in the deposition during the initial steps using infared spectroscopy (Brewer et al, 2004).…”

“…Brewer et al have used a thermal N2-NH3 pretreatment prior to deposition and have shown an increase in the deposition during the initial steps using infared spectroscopy (Brewer et al, 2004). Lu et al have performed an ex situ NH3 plasma pre-treatment, which exhibited an increased ALD deposition during the initial steps (Lu et al, 2007). Xu et al have compared Al2O3 films deposited by ALD on Si surfaces pre-treated ex situ by NH3 plasma and long TMA exposures prior to deposition, in terms of thermal and electrical properties (Xu et al, 2006).…”