Statistical investigations of an ENIG Nickel film morphology by Atomic Force Microscopy

Abstract

The morphology of a Nickel layer grown by an Electroless Nickel Immersion Gold (ENIG) technique used for microelectronics interconnections is determined by Atomic Force Microscopy (AFM) investigations. The root mean square (rms) roughness, determined over a scanned area is a function of the AFM scanned area size. In this work, we propose to consider the dynamic scale theory and the power spectrum density (PSD) analysis in order to perform a comprehensive determination of the surface properties of the ENIG nickel layer. Results highlight the existence of a first regime with a roughness exponent of 0.95 and a fractal dimension (DF) of the nickel film about 2.05. This case study is presented in order to propose further investigations. In fact, same experimental procedure should be performed in a magnetic shielded zone where a very low noise level is available such as the Low-Noise Underground Laboratory (LSBB) of Rustrel (France).