Characterization of nanoscaled solder material



The properties of nanoscaled layers of pure tin have been studied. The layers were produced by sputtering in different thicknesses between 10 and 100 nm. The surface topography and the influence of process parameters on the sputtering rate were characterized using scanning electron microscopy (SEM) and atomic force microscopy (AFM) methods. To avoid oxidation carbon and silicon nitride protective layers were sputtered in the same process chamber. The function of this coating was investigated by X-ray diffraction (XRD). The crystallographic structure of tin layer under silicon nitride was measured directly after sputtering, melting and cooling processes. The crystalline tin film after cooling down and the absence of tin oxide peaks were used as indicators for impermeability of oxygen. For investigation of phase change the method of chip differential calorimetry (DSC) was used. The samples were prepared as standalone samples for reuse of DSC-chips and also sputtered directly on the DSC chip for single use. The prepared samples with one tin layer and multilayer of tin scaled down to 10 nm were investigated with this method.