Thickness measurement of interfacial layer between HfO$_2$ film and Si substrate by Fourier analysis of x-ray reflectivity

Thickness of interfacial layers between Si-substrates and HfO$_2 $ films have been estimated by Fourier analysis of x-ray reflectivity. It is demonstrated that enhancement of the signals corresponding to the positions of low-density-contrast interfaces can be achieved through careful data processing in Fourier analysis. Details of the data processing procedures and comparison between results of the analysis and TEM measurements are presented.