Abstract:
A step-by-step framework for undertaking PSD characterization of the surface
topography of radio frequency (rf) magnetron sputtered thin Al films is presented in this chapter. The work aims to illustrate the significance of PSD method
in analyzing the surface properties of thin films based on AFM imaging. It also
aims at illustrating a repeatable procedure for undertaking PSD analysis on thin
films. Brief theoretical background of power spectral density, with highlights on
the fundamental theory, is herein presented. A two-dimensional power spectral
computation of thin Al films sputtered on a titanium substrate at 150 W and
200 W rf powers for 2 hr is undertaken. Prior to the computation, a detailed image
analysis theory and procedure of the AFM micrographs are presented. The calculation of power densities of the AFM images is conducted using the fast Fourier
(FFT) algorithm of discrete Fourier transformation (DFT) in MATLAB script. The
power spectral results are then fitted into k-correlation and inverse power models
to interpret the spectral profiles. From the modelling, the equivalent root means
square, correlation length and Hurst components have been determined. These
values were distinctly discussed in relation to the sputtering power and morphological observations of the 3D AFM microscopy. The PSD results correlate well
with the morphological observations of the atomic force microscopy.