Thin films have found extensive applications in daily life. Well-known examples are optical coatings, hard coatings, decorative coatings, semiconductor structures and thin films for magnetic recording. Investigation of thin film growth has mostly been dedicated to the development of deposition procedures. Nevertheless, a more fundamental insight into layer growth at the nano-scale has shown to be essential for the development of deposition procedures. Two examples in the field of layer growth at the nano-scale will be highlighted: a fundamental investigation at the nano-scale of TiN layer growth and the investigation of layer growth at nano-scale thickness for Mo/Si multilayers.