X-ray reflectometry and spectroscopic ellipsometry characterization of Al 2 O 3 atomic layer deposition on HF-last and NH 3 plasma pretreatment Si substrates

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.