Fractal Analysis of Island Structures of Al Thin Films

Abstract

Micro-island-structures with a diameter in a sub-micron range obtained in the initial stage of thin film growth are interesting to modify surface morphology or to vary surface area of micro devices. In such applications, the size and similarity of islands are thought to be important. In this study, Al micro islands on the Ti underlayer surface obtained by magnetron sputtering have been estimated by a fractal analysis method to estimate their statistical similarity by using an atomic force microscopy (AFM) as a function of Al amount deposited. In relation to this. surface characteristic factors such as average roughness, average diameter, bearing ratio have been estimated by using surface topology data obtained by AFM. The results show that the fractal dimension varies from about 2 to 3 as a deposited Al amount increased, showing the growth mode changed from two-dimensional to three-dimensional. An island structure with a similar topographical shape was obtained at a range of At amounts, yielding fractal dimensions of about 1.9 to 2.2.