Determination of the Au/SiNx interfacial energy by AFM and FIB tomography

Thin metal films can break up into particles upon annealing, a process called dewetting. In this work gold particles on SiNx formed by dewetting are characterized with respect to their radius and height. Based on the Winterbottom construction a method for the determination of interfacial energies by AFM is proposed. The AFM method provides an average value of the interfacial energy over many particles. It is easier to apply and does not rely on expensive machinery such as the concurrent methods (e.g. FIB tomography, TEM lamella preparation). The prerequisites for the AFM method to give reliable results are critically discussed. The Au/SiNx interfacial energy is measured with the AFM method and compared to a measurement by FIB tomography to directly assess the reliability of the new method. It is shown that in the Au/SiNx system the majority of the particles do not reach their equilibrium shape. Since it is a prerequisite of the AFM method that the particles have attained their equilibrium shape, the interfacial energy is determined from a subset of data comprising particles that presumably have reached the equilibrium shape. The determined interfacial energies of 0.93 +/0.05 J/m2 for the AFM approach and 0.90 +/0.15 J/m2 for the FIB based approach are in good agreement, which suggests that the chosen approach is valid.