Thin film thickness measurement by the conductivity theory in the framework of Born approximation

• Inverse method for estimating thin layer thickness using electric conductivity
• Cross correlations of two rough surfaces increases/decreases the conductivity.
• Efficiency of surface coupling is inversely proportional to layer thickness.
• Capacitance resistance due to AC and local resistance are both effective.
• Under AC current, height fluctuations on substrates resemble an RC circuit.

When the thickness of a layer is smaller than the electrons mean free path, the conductivity would be directly affected by the morphology. This issue provides a basis for estimating the thickness of the layer by understanding the morphology and the value of conductivity. This method is an inverse approach on thickness estimation and is applied to various samples. The comparison of the results with other thickness estimations shows good consistency. The benefit of this approach is that the only parameter that needs to be measured is the conductivity, which is quite trivial. Despite the simplicity of this approach, its results would prove adequate for studying both the material properties and the morphology of the layer. In addition, the possibility of repeating measurements on the thickness for AC currents with various frequencies enables the process of averaging the measurements in order to obtain the most precise results.