Abstract
Previously, the author suggested that the atomic layer deposition (ALD) of an amorphous high-k dielectric thin film has a surface smoothing effect on a rough surface. In this paper, the author points out that for ALD high-k dielectric materials which tend to be polycrystalline, the situation is different. When the film is very thin, it can be amorphous with a surface smoothing effect; when the film is thicker than a critical thickness, it can be polycrystalline with a surface roughening effect. An asymmetry in interfacial roughness will lead to an asymmetry in the top and bottom Schottky barrier heights, resulting in I-V polarity asymmetry. The significance of this theory on the leakage current mechanism of ZAZ MIM capacitors used in DRAM technology will be explained.
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