Effect of the Different Substrates and the Film Thickness on the Surface Roughness of Step Structure

The surface roughness was important for the nanostructure, especially for the geometry standard in the future. The AlO film was grown on Si and SiN substrate by plasma-assisted atomic layer deposition (ALD) technique, and the nanostep structure was obtained on the AlO thin film. The roughness of all kinds of surface (Si and SiN substrates, AlO films with different thickness and the step structures with different height) was researched by atomic force microscopy (AFM). Analysis of the surface roughness revealed that the roughness of the AlO step was related to the film thickness and the type of substrate. The surface roughness of the lower surface of the step structure is larger than that of the substrate. Both the Si substrate and the SiN substrate have the same rules in the rate of change of surface roughness, so the change of film roughness may be related to the initial roughness of the substrate or the substrate material. No matter the surface roughness of film or the surface roughness of step structure, the Si substrate was superior to that on the SiN substrate. Because the surface energy of Si is smaller than that of SiN. The surface roughness can be further reduced by optimizing the process parameters or reducing the surface energy of the substrate through other processes.