The Application of a Selective Etch to Conclusively Show the Surface Smoothing Effect of an Amorphous Thin Film Deposited by Atomic Layer Deposition

It can be predicted by theory that the atomic layer deposition (ALD) of an amorphous high-k dielectric thin film on a rough bottom metal electrode has a surface smoothing effect, resulting in a smoother top surface. This effect can strongly affect the electrical characteristics of high-k MIM capacitors. Sometimes this effect may be hard to observe by atomic force microscopy (AFM) because the bottom metal electrode may be modified by the ALD process, resulting in an apparently contradictory AFM measurement. The solution is to use a chemically and physically stable metal with a Hüttig temperature larger than the ALD temperature. In addition, AFM after a selective etch is very useful in order to demonstrate the surface smoothing effect by ALD conclusively.